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Mersana Therapeutics

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FY2022 Annual Report · Mersana Therapeutics
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MERSANA THERAPEUTICS, INC.

2022 Annual Report to Stockholders

UNITED STATES 
SECURITIES AND EXCHANGE COMMISSION 
Washington, D.C. 20549 

FORM 10-K 

(Mark One) 

  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

 

TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2022. 

OR 

For the transition period from                    to                    

Commission file number 001-38129 
Mersana Therapeutics, Inc. 
(Exact name of registrant as specified in its charter) 

Delaware 
(State or Other Jurisdiction of Incorporation or Organization) 

04-3562403 
(I.R.S. Employer Identification No.) 

840 Memorial Drive Cambridge, MA 
(Address of Principal Executive Offices) 

02139 
(Zip Code) 

Registrant’s telephone number, including area code (617) 498-0020 

Title of each class 
Common Stock, $0.0001 par value 

Securities registered pursuant to Section 12(b) of the Act: 
Trading symbol(s) 
MRSN 

Securities registered pursuant to Section 12(g) of the Act: 

NONE 

Name of each exchange on which registered 
The Nasdaq Global Select Market 

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.            Yes    No   

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.            Yes    No   
Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during 
the preceding 12 months (or for such shorter period that registrant was required to file such reports), and (2) has been subject to such filing requirements for the 
past 90 days.            Yes    No   
Indicate  by  check  mark  whether  the  registrant  has  submitted  electronically  every  Interactive  Data  File  required  to  be  submitted  pursuant  to  Rule 405  of 
Regulation  S-T  (§232.405  of  this  chapter)  during  the  preceding  12  months  (or  for  such  shorter  period  that  the  registrant  was  required  to  submit  such 
files).            Yes    No   
Indicate  by  check  mark  whether  the  registrant  is  a  large  accelerated  filer,  an  accelerated  filer,  a  non-accelerated  filer,  a  smaller  reporting  company,  or  an 
emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” 
in Rule 12b-2 of the Exchange Act. 

Large accelerated filer 
Non-accelerated filer 

 
 

Accelerated filer 
Smaller reporting company 
Emerging growth company 

 
 
 

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or 
revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.                
Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control 
over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its 
audit report.               
If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing 
  
reflect the correction of an error to previously issued financial statements. 
Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by 
any of the registrant's executive officers during the relevant recovery period pursuant to § 240.10D-1(b). 
Indicate by check mark whether the registrant is a shell company (as defined by Rule 12b-2 of the Exchange Act).            Yes    No   
As  of  June  30,  2022,  the  last  business  day  of  the  registrant’s  most  recently  completed  second  fiscal  quarter,  the  aggregate  market  value  of  the  registrant’s 
common stock held by non-affiliates was $403,311,770, based on the last reported sale price of such stock on the Nasdaq Global Select Market as of such date. 
As of February 24, 2023, the registrant had 108,026,074 shares of common stock outstanding at a par value $0.0001 per share. 

  

Portions of the registrant’s definitive proxy statement that will be filed for the 2023 Annual Meeting of Stockholders within 120 days of the end of the 
registrant’s fiscal year ended December 31, 2022 are incorporated by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. 

DOCUMENTS INCORPORATED BY REFERENCE 

 
 
 
 
  
 
 
 
 
 
TABLE OF CONTENTS 

Page 

SPECIAL NOTE REGARDING FORWARD LOOKING STATEMENTS 

RISK FACTOR SUMMARY 

ITEM 1. 

BUSINESS 

ITEM 1A. 

RISK FACTORS 

ITEM 1B. 

UNRESOLVED STAFF COMMENTS 

ITEM 2. 

PROPERTIES 

ITEM 3. 

LEGAL PROCEEDINGS 

ITEM 4. 

MINE SAFETY DISCLOSURES 

PART I 

PART II 

ITEM 5. 

MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER 
MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES 

ITEM 6. 

[RESERVED] 

ITEM 7. 

MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND 
RESULTS OF OPERATIONS 

ITEM 7A. 

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK 

ITEM 8. 

FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA 

ITEM 9. 

CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND 
FINANCIAL DISCLOSURE 

ITEM 9A. 

CONTROLS AND PROCEDURES 

ITEM 9B. 

OTHER INFORMATION 

ITEM 9C. 

DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS 

PART III 

ITEM 10. 

DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE 

ITEM 11  

EXECUTIVE COMPENSATION 

ITEM 12. 

ITEM 13. 

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT 
AND RELATED STOCKHOLDER MATTERS 

CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR 
INDEPENDENCE 

ITEM 14. 

PRINCIPAL ACCOUNTANT FEES AND SERVICES 

PART IV 

ITEM 15. 

EXHIBIT AND FINANCIAL STATEMENT SCHEDULES 

ITEM 16. 

FORM 10-K SUMMARY 

SIGNATURES 

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REFERENCES TO MERSANA 

Throughout this Annual Report on Form  10-K,  the “Company,”  “Mersana,”  “we,” “us,” and “our,” except  where the context 
requires otherwise, refer to Mersana Therapeutics, Inc. and its consolidated subsidiary, and “our board of directors” refers to the 
board of directors of Mersana Therapeutics, Inc. 

SPECIAL NOTE REGARDING FORWARD LOOKING STATEMENTS 

This Annual Report on Form 10-K contains forward-looking statements. Forward-looking statements are neither historical facts 
nor assurances of future performance. Instead, they are based on our current beliefs, expectations and assumptions regarding the 
future  of  our  business,  future  plans  and  strategies,  our  clinical  results  and  other  future  conditions.  The  words  “aim,” 
“anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “goal,” “intend,” “may,” “on track,” “plan,” 
“possible,” “potential,” “predict,” “project,” “seek,” “should,” “target,” “will,” “would” or the negative of these terms or other 
similar  expressions  are  intended  to  identify  forward-looking  statements,  although  not  all  forward-looking  statements  contain 
these identifying words. 

These forward-looking statements include, among other things, statements about: 

• 

• 

• 

• 

• 

• 

• 

• 

• 

the  initiation,  cost,  timing,  progress  and  results  of  our  current  and  future  research  and  development  activities, 
preclinical  studies  and  clinical  trials,  including  the  expected  timing  of  reporting  of  data  from  our  ongoing  clinical 
trials; 

the  adequacy  of  our  inventory  of  upifitamab  rilsodotin,  or  UpRi,  XMT-1660,  XMT-2056  and  our  other  product 
candidates to support our ongoing and planned clinical trials, as well as the outcome of planned manufacturing runs; 

the timing of, and our ability to obtain and maintain, regulatory approvals for our product candidates; 

unmet needs of patients with ovarian cancer, breast cancer and other cancer indications; 

our ability to quickly and efficiently identify and develop additional product candidates; 

our ability to advance any product candidate into, and successfully complete, clinical trials; 

our intellectual property position, including with respect to our trade secrets; 

the potential benefits of strategic collaborations and our ability to enter into selective strategic collaborations; 

our  estimates  regarding  expenses,  future revenues,  capital requirements,  the  sufficiency of  our  current  and  expected 
cash resources and our need for additional financing; and 

• 

the potential impact of the ongoing COVID-19 pandemic. 

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should 
not  place  undue  reliance  on  our  forward-looking  statements. Actual  results  or  events  could  differ  materially  from  the  plans, 
intentions and expectations disclosed in  the forward-looking statements we make. We have included important  factors  in the 
cautionary statements included in this Annual Report on Form 10-K, particularly in the “Risk Factors” section, that we believe 
could cause actual results or events to differ materially from the forward-looking statements that we make. Our forward-looking 
statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we 
may make. 

The forward-looking statements contained herein represent our views as of the date of this Annual Report on Form 10-K and 
we  do  not  assume  any  obligation  to  update  any  forward-looking  statements,  whether  as  a  result  of  new  information,  future 
events or otherwise, except as required by law. We anticipate that subsequent events and developments will cause our views to 
change. You should, therefore, not rely on these forward-looking statements as representing our views as of any date subsequent 
to the date of this Annual Report on Form 10-K. 

2 

 
 
 
 
 
RISK FACTOR SUMMARY 

Our  business  is  subject  to  varying  degrees  of  risk  and  uncertainty.  Investors  should  consider  the  risks  and  uncertainties 
summarized below, as well as the risks and uncertainties discussed in Part I, Item 1A,  Risk Factors of this Annual Report on 
Form 10-K.  

Our business is subject to the following principal risks and uncertainties: 

•  We have incurred net losses since our inception, we have no products approved for commercial sale and we anticipate 

that we will continue to incur substantial operating losses for the foreseeable future. 

•  We  will  require  substantial  additional  financing  to  achieve  our  goals,  and  a  failure  to  obtain  this  necessary  capital 
when needed could force us to delay, limit, reduce or terminate our product development or commercialization efforts. 

•  We have a credit facility that requires us to meet certain affirmative and negative covenants and places restrictions on 

our operating and financial flexibility. 

•  We  face  substantial  competition,  which  may  result  in  others  discovering,  developing  or  commercializing  products 

before, or more successfully than, we do. 

•  We only have a limited number of product candidates being evaluated in clinical trials. A failure of any of our current 
or  future  product  candidates  in  clinical  development  could  adversely  affect  our  business  and  may  require  us  to 
discontinue development of other product candidates based on the same technology. 

•  We can provide no assurance that our product candidates will obtain regulatory approval or that the results of clinical 

trials will be favorable. 

•  Drug discovery and development is a complex, time-consuming and expensive process that is fraught with risk and a 
high  rate  of  failure.  We  can  provide  no  assurance  of  the  successful  and  timely  development  of  new  antibody-drug 
conjugate, or ADC, products. 

• 

If  we  fail  to  attract  and  retain  senior  management  and  key  scientific  personnel,  we  may  be  unable  to  successfully 
develop our product candidates, conduct our clinical trials and commercialize our product candidates. 

•  We may encounter difficulties in managing our growth and expanding our operations successfully. 

•  Our  activities,  including  our  interactions  with  healthcare  providers,  third  party  payors,  patients  and  government 
officials,  are,  and  will  continue  to  be,  subject  to  extensive  regulation  involving  health  care,  anti-corruption,  data 
privacy and security and consumer protection laws. Failure to comply with applicable laws could result in substantial 
penalties,  contractual  damages,  reputational  harm,  diminished  revenues  and  curtailment  or  restructuring  of  our 
operations. 

•  We rely upon patents and other intellectual property rights to protect our technology. We may be unable to protect our 

intellectual property rights, and we may be liable for infringing the intellectual property rights of others. 

•  Unfavorable  global  economic  or  geopolitical  conditions  could  adversely  affect  our  business,  financial  condition  or 

results of operations. 

INDUSTRY DATA 
This Annual Report on Form 10-K may include industry and market data, which we may obtain from our own internal estimates 
and research, as well as from industry and general publications and research, surveys, and studies conducted by third parties. 
Industry  publications,  studies,  and  surveys  generally  state  that  they  have  been  obtained  from  sources  believed  to  be reliable, 
although  they  do  not  guarantee  the  accuracy  or  completeness  of  such  information.  While  we  believe  that  such  studies  and 
publications are reliable, we have not independently verified market and industry data from third‑party sources. 

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NOTE REGARDING TRADEMARKS 
We own various trademark registrations and applications, and unregistered trademarks, including our name and our corporate 
logo. All other trade names, trademarks and service marks of other companies appearing in this report are the property of their 
respective holders. Solely for convenience, the trademarks and trade names in this report may be referred to without the ®,™ or 
© symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the 
fullest extent under applicable law, their rights thereto. We do not intend to use or display other companies' trademarks and 
trade names to imply a relationship with, or endorsement or sponsorship of us by, any other companies. 

4 

 
ITEM 1. 

BUSINESS 

Overview 

PART I 

We  are  a  clinical-stage  biopharmaceutical  company  focused  on  developing  antibody-drug  conjugates,  or ADCs,  that  offer  a 
clinically  meaningful  benefit  for  cancer  patients  with  significant  unmet  need.  We  have  leveraged  over  20  years  of  industry 
learning in the ADC field to develop three proprietary and differentiated platforms that enable us to develop ADCs designed to 
have improved efficacy, safety and tolerability relative to existing ADCs and other approved therapies. 

We believe that our innovative platforms and our proprietary payloads together enable a robust discovery pipeline for us and 
our  collaborators.  Our  investments  in  our  novel  and  proprietary  auristatin  DolaLock  payload,  as  well  as  our  novel  and 
proprietary  STING  (stimulator  of  interferon  genes)  agonist  ImmunoLock  payload,  together  with  the  good  manufacturing 
practices supply chain established for our Dolaflexin, Dolasynthen and Immunosynthen platforms, enable our ability to apply 
these platforms to new and different targets and antibodies to create new product candidates. We call this our product engine. 
Our ADCs  in  preclinical  studies  and  clinical  trials  include first-in-class  molecules  that  target  multiple  tumor  types  with  high 
unmet medical need.  

We have assembled a management team with extensive and relevant experience, including specific ADC experience, from prior 
work  at  leading  pharmaceutical  companies  such  as  Bayer AG;  Bristol  Myers  Squibb,  or  BMS;  Centocor  Inc.;  Constellation 
Pharmaceuticals,  Inc.;  Cubist  Pharmaceuticals,  Inc.;  GlaxoSmithKline  plc;  Millennium  Pharmaceuticals,  Inc.;  Momenta 
Pharmaceuticals, Inc.; Sanofi S.A.; Sunovion Pharmaceuticals Inc.; Takeda Pharmaceuticals, Inc., or Takeda; Tesaro, Inc. and 
Vertex Pharmaceuticals Inc. We are supported by our board of directors and scientific advisory board, who offer complementary 
experience  in  drug  discovery,  development  and  commercialization,  business  development  and  public  company  management. 
We believe that our highly differentiated platforms, together with the team we have assembled, position us well to discover and 
develop life-changing ADCs for patients fighting cancer. 

Strategy 
Our  goal  is  to  become  a  leading  oncology  company  by  leveraging  the  potential  of  our  innovative  and  differentiated  ADC 
platforms  and  the  experience  and  competencies  of  our  management  team  to  discover  and  develop  promising ADC  product 
candidates and to commercialize cancer therapeutics that address unmet medical needs or provide significant benefit to patients. 
We believe that executing against the following strategic objectives will help us achieve our goal: 

•  Build UpRi (upifitamab rilsodotin) into a Foundational Medicine in Ovarian Cancer. Our lead product candidate, 
upifitamab rilsodotin, which we refer to as UpRi, is a first-in-class Dolaflexin ADC targeting NaPi2b, an antigen 
broadly expressed in ovarian cancer and other cancers. We are currently evaluating UpRi in patients with platinum-
resistant ovarian cancer in a single-arm registrational trial, which we refer to as UPLIFT, for which we completed 
enrollment of approximately 270 patients in October 2022. We expect to report top-line data from UPLIFT in mid-
2023 following the major oncology conferences scheduled for June, and, if the data are positive, to submit a biologics 
license application, or BLA, to the U.S. Food and Drug Administration, or FDA, under the accelerated approval 
pathway around the end of 2023. We also initiated screening of patients in UP-NEXT, our Phase 3 clinical trial of 
UpRi as monotherapy maintenance treatment following treatment with platinum doublets in recurrent platinum-
sensitive ovarian cancer, in the third quarter of 2022, and we continue to enroll patients in this trial. If data from the 
trial are positive, we believe UP-NEXT could serve as a post-approval confirmatory trial in the United States, support 
potential approvals outside of the United States and support UpRi’s expansion into earlier lines of therapy. 
Additionally, we are also conducting a Phase 1 combination trial, which we refer to as UPGRADE-A, exploring the 
combination of UpRi with carboplatin, a standard platinum chemotherapy broadly used in the treatment of platinum-
sensitive ovarian cancer. We have completed the dose escalation portion of UPGRADE-A, initiated the dose expansion 
portion of UPGRADE-A in January 2023, and expect to present interim data from the trial in the second half of 2023. 
We may explore UpRi in combination with other therapies in a series of UPGRADE trials. Together, we believe that 
data from all of our clinical trials of UpRi have the potential to establish the safety and efficacy of UpRi across a wide 
range of ovarian cancer patients, from those who are platinum-resistant and heavily pre-treated to those in earlier lines 
of treatment for the disease. The European Commission granted orphan medicinal product designation to UpRi for the 
treatment of ovarian cancer in December 2022.  

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•  Build Out Our Pipeline of Highly Impactful Cancer Medicines. We are investigating two additional ADC product 

candidates, XMT-1660 and XMT-2056, in Phase 1 clinical trials. XMT-1660 is a B7-H4-directed Dolasynthen ADC 
designed with a precise, target-optimized drug-to-antibody ratio, or DAR, of 6 and our DolaLock microtubule inhibitor 
payload with controlled bystander effect. We are currently enrolling patients in our multicenter Phase 1 trial 
investigating the safety, tolerability and anti-tumor activity of XMT-1660 in patients with breast, endometrial and 
ovarian cancers, and began dosing patients in August 2022. We expect to complete the dose escalation portion of this 
trial in 2023. The FDA has granted Fast Track designation to XMT-1660 for the treatment of adult patients with 
advanced or metastatic triple-negative breast cancer. XMT-2056 is a systemically administered Immunosynthen 
STING agonist ADC (DAR 8) that is designed to target a novel epitope of human epidermal growth factor receptor 2, 
or HER2, distinct from that targeted by either trastuzumab or pertuzumab, and to locally activate STING signaling in 
both tumor-resident immune cells and in tumor cells, providing the potential to treat patients with HER2-high or -low 
tumors as monotherapy and in combination with standard-of-care agents. We initiated a multicenter Phase 1 open-label 
trial of XMT-2056 in previously treated patients with advanced/recurrent solid tumors expressing HER2, including 
breast, gastric, colorectal and non-small cell lung cancers, in January 2023. The FDA granted orphan drug designation 
to XMT-2056 for the treatment of gastric cancer in May 2022. 

•  Build Innovation and Scientific Leadership in ADCs. We believe we are establishing a leading position in the field 
of  ADCs  by  leveraging  our  existing  platforms,  Dolaflexin,  Dolasynthen  and  Immunosynthen,  and  continuing  to 
advance new innovations. Additionally, we are discovering new product candidates for ourselves and for collaborators 
that  we  believe  hold  the  potential  to  be  first-  and  best-in-class  medicines  for  patients  with  cancer  in  areas  of  high 
unmet  medical  need.  XMT-2068  and  XMT-2175  are  among  our  preclinical  candidates  that  leverage  our 
Immunosynthen platform.  

•  Build Relationships with Strategic Collaborators. We aim to leverage our technical expertise and experience with 
respect to our innovative and diversified platforms, to attract and cultivate strategic collaborations that facilitate our 
ability to bring differentiated product candidates to patients. We have established strategic research and development 
collaborations with Janssen Biotech, Inc., or Janssen, and Merck KGaA, Darmstadt, Germany, or Merck KGaA, and 
its affiliate Ares Trading S.A., or MRKDG, for the development and commercialization of additional ADC product 
candidates leveraging our proprietary Dolasynthen, Dolaflexin and Immunosynthen platform technologies against a 
limited number of targets selected by our collaborators. We have also granted GlaxoSmithKline Intellectual Property 
(No. 4) Limited, or GSK, an exclusive option for an exclusive global license to co-develop and commercialize XMT-
2056. We believe the potential of our ADC technologies, supported by our scientific and technical expertise and 
enabled by our intellectual property strategy, all support our independent and collaborative efforts to discover and 
develop life-changing ADCs for patients fighting cancer. 

•  Build Mersana with Top Talent. We aim to attract and retain talented team members with deep experience in drug 
discovery, development, manufacturing, and commercialization as well as in general business and administration. Our 
team is driven by a shared passion to advance therapies that can make a significant difference in the lives of cancer 
patients. We will continue to cultivate the collaborative and passionate workplace culture and diverse workforce that 
has allowed us to advance this mission. 

6 

 
 
 
 
Our current pipeline is summarized in the chart below: 

ADC Background 

ADCs are a validated therapeutic modality in oncology with 11 products currently approved for use by the FDA, and over 100 
being  tested  in  clinical  trials.  We  believe  that  the  field  has  not  yet  realized  its  full  potential  due  to  the  limitations  of  first-
generation ADCs and a scarcity of clinically meaningful platform innovation.  

First-generation ADCs were developed to deliver cytotoxic therapy specifically to neoplastic cells while sparing normal tissue. 
A cytotoxic ADC consists of three components: the antibody, the cytotoxic payload, and a linker to join the two. The antibody 
portion of the ADC achieves specific targeting by binding to an antigen that ideally has high expression on the surface of the 
tumor  cells  and  low  expression  in  healthy  tissues.  Once  the  antibody  binds  to  the  target,  the ADC  enters  the  cell,  and  the 
payload is typically released, killing the cell.  

The payload, the DAR, the linker, and conjugation site of the linker with the antibody all can influence the overall efficacy and 
tolerability of ADCs. There has been limited innovation in these ADC components  since the development of first-generation 
ADC  platforms. We  believe  optimizing  an ADC  requires  developing  payload(s)  with  optimal  properties,  varying  DAR  for  a 
specific target, and optimizing the conjugation site, all of which can contribute to the overall drug-like properties. We believe 
that our proprietary platforms improve upon first-generation ADC approaches in these aspects and have the potential to advance 
the field and improve patient outcomes. 

7 

 
 
 
 
 
Our Technologies and Platforms 

We  believe  the  development  of  ADCs  is  not  a  one-size-fits-all  approach.  In  fact,  a  number  of  diverse  factors  impact  the 
properties of an ADC, including payload, DAR, site of conjugation and homogeneity. For each target antigen, there may be an 
optimal combination of these factors. Our novel and highly differentiated platforms are designed to allow us to optimize these 
properties for a given target and develop ADCs that are designed to best address patient needs. 

DolaLock Payload 

We  refer  to  the  cytotoxic  payload  we  use  with  our  Dolaflexin  and  Dolasynthen  platforms  as  our  DolaLock  payload.  Our 
DolaLock  payload  is  a  highly  potent,  proprietary  auristatin  anti-tubulin  agent  selectively  toxic  to  rapidly  dividing  cells.  The 
DolaLock payload has been shown in in vitro and in vivo preclinical studies to control the bystander effect by locking the 
cytotoxic  drug  inside  cells  after  allowing  a  short  period  of  antigen-independent  diffusion  throughout  the  tumor. As  the  drug 
diffuses through neighboring cells, the DolaLock payload is metabolized to a form that is still highly potent but is designed to 
no longer be able to cross the cell membrane. We believe this “controlled bystander effect” may allow for enhanced safety and 
efficacy. 

A  common  mechanism  of  resistance  in  cancer  is  the  up-regulation  of  multi-drug  resistance,  or  MDR,  pumps,  such  as  P-
glycoproteins,  or  PgPs,  which  can  actively  pump  drugs  out  of  cancer  cells  to  help  them  survive.  Once  metabolized,  our 
DolaLock  payload  is  not  a  substrate  for  PgPs,  thereby  avoiding  this  resistance  mechanism.  Our  DolaLock  payload,  with  its 
controlled  bystander  effect,  is  designed  to  enable  the  creation  of ADCs  that  have  the  potential  of  being  highly  potent,  well-
tolerated and specifically targeted cancer therapies. 

In addition, our proprietary auristatin payload has also been shown in preclinical studies to cause immunogenic cell death and 
to  stimulate  the  immune  system  through  dendritic  cell  activation.  Because  of  this,  we  have  observed  synergy  with  immuno-
oncology agents such as PD-1 inhibitors in preclinical models. 

Dolaflexin Platform 

The  Dolaflexin  platform  was  designed  to  increase  the  efficacy,  safety  and  tolerability  of  ADCs.  Dolaflexin  utilizes  our 
proprietary  Fleximer  polymer,  a  biodegradable,  highly  biocompatible,  water-soluble  polymer  that  is  able  to  carry  multiple 
payloads.  Instead  of  direct  conjugation  to  an  antibody,  payloads  are  attached  through  an  optimized,  cleavable  linker  to  the 
Fleximer scaffold, which is then conjugated to the antibody through a non-cleavable linker. Our Fleximer polymer allows for an 
increased  number  of payloads  carried  by  each ADC  as  compared  to  other ADC  therapies  and  has  demonstrated  dramatically 
improved drug solubility and pharmacokinetics with higher DAR. 

As a result, we believe Dolaflexin has the potential to offer the following benefits relative to first-generation ADCs: 

•  Proprietary DolaLock Payload: Dolaflexin is loaded with our proprietary auristatin cytotoxic drug, which is a highly 

potent anti-tubulin agent that is selectively toxic to rapidly dividing cells and has a controlled bystander effect. 

•  Higher  Drug-to-Antibody  Ratio:  Historically, ADCs  typically  have  been  limited  to  a DAR  of  3-4. The  Dolaflexin 
platform  can deliver ADCs with DAR of  approximately  10,  which has enabled ADCs  created using this platform  to 
demonstrate greater preclinical efficacy while also maintaining pharmacokinetics and drug-like properties. 

•  Expanded Range of Addressable Tumor Targets: The higher DAR enabled by Dolaflexin results in a higher amount 
of cytotoxic drug released into the tumor cell for every ADC that is internalized. As a result, we believe that Dolaflexin 
ADCs may demonstrate efficacy against tumor targets with lower levels of antigen expression that traditional ADCs 
have been unable to address. 

We believe  Dolaflexin’s advantageous characteristics  provide  a substantial opportunity to  address a broader  range of cancers 
than first generation ADC-based approaches. Our lead clinical candidate, UpRi, is a Dolaflexin ADC that targets NaPi2b. We 
are currently evaluating UpRi in the UPLIFT, UP-NEXT and UPGRADE-A clinical trials. 

Dolasynthen Platform 

The Dolasynthen platform enables an iterative approach to designing customized ADCs for a given target while retaining the 
use of our proprietary DolaLock payload for a controlled bystander effect. Dolasynthen ADCs consist of a proprietary synthetic 
scaffold  carrying  an  exact  number  of  DolaLock  payloads  for  precise  control  of  DAR.  The  Dolasynthen  scaffold  is  then 

8 

 
 
 
 
 
 
 
 
 
 
bioconjugated  to  the  antibody  in  a  site-specific  manner.  The  Dolasynthen  scaffold  has  been  precisely  designed  to  provide 
optimal water solubility, charge balance, linker stability and DAR, which together offer an opportunity for our ADCs to have 
superior physicochemical and pharmacokinetic properties relative to other ADC therapies. 

We believe Dolasynthen ADCs have broad therapeutic potential as cancer therapies, and our preclinical data demonstrate the 
ability of the Dolasynthen platform to generate and identify the optimal ADC for a given target and antibody. 

We  believe  that  Dolasynthen  offers  the  benefits  of  Dolaflexin,  including  the  proprietary  DolaLock  payload,  while  also 
providing the following potential additional benefits relative to traditional ADC platforms: 

•  Precise Control of DAR: The optimal DAR may vary between different targets and antibodies. Dolasynthen uses a 
proprietary scaffold that allows for precise DARs between two and 24, enabling optimization of the DAR for specific 
antigens and antibodies. 

•  Site-Specific Bioconjugation: The site of scaffold bioconjugation to an antibody impacts the overall properties of that 

ADC. Dolasynthen enables site-specific bioconjugation, allowing further ADC optimization. 

•  Homogenous ADC Development: The DAR and antibody bioconjugation is consistent for each ADC developed with 
the Dolasynthen platform, allowing for consistent and precise drug delivery to targeted cancer cells. We believe this 
homogeneity may allow for enhanced safety, tolerability and efficacy. 

• 

Increased  Hydrophilicity:  The  precise  optimization  of  the  hydrophilic  moiety  on  Dolasynthen  ADCs  allows  for 
increased aqueous solubility and enhanced pharmacokinetic properties. 

We are currently conducting a Phase 1 clinical trial of XMT-1660, our B7-H4-targeted Dolasynthen ADC. 

ImmunoLock Payload  

We refer to the STING agonist that is used as the payload with our Immunosynthen platform as our ImmunoLock Payload. It 
was designed to have very low cell permeability in order to control delivery and localization of its innate immune-activating 
effect. STING is a well-studied innate immune pathway capable of inducing anti-tumor immune activity. Our preclinical data 
show  that  the  anti-tumor  activity  of  Immunosynthen  ADCs  carrying  the  ImmunoLock  payload  is  driven  by  the  targeted 
activation  of  the  STING  pathway  in  tumor-resident  immune  cells  and  in  tumor  cells,  in  a  target-dependent  manner.  STING 
pathway activation in both cell types within the tumor provides the potential for enhanced anti-tumor activity with a STING-
agonist ADC compared to other innate immune approaches, such as toll-like receptor, or TLR, agonists, that activate only the 
immune cells and are not capable of activating the tumor cells. 

Immunosynthen Platform 

Immunosynthen  is  our  novel  immunostimulatory  ADC  platform  designed  to  take  ADCs  beyond  the  delivery  of  traditional 
cytotoxic payloads by enabling the targeted stimulation of the innate immune system. Through the tumor-targeted delivery of a 
novel STING agonist, ADCs created with our Immunosynthen platform have the potential to address the challenges of efficacy, 
delivery  and  tolerability  posed  by  intratumoral  or  intravenous  injection  of  free  (unconjugated)  STING  agonists.  We  have 
generated preclinical data across multiple, diverse targets by creating Immunosynthen ADCs based on a variety of antibodies 
directed to those targets and evaluating them in a range of tumor models. In each case, we have demonstrated significant anti-
tumor  activity  in  vivo  (including  complete  tumor  regressions)  after  a  single  low,  well-tolerated  dose.  Additional 
characterization has demonstrated increased cytokine expression and immune cell infiltration in the tumor microenvironment, 
as  well  as  the  induction  of  immunological  memory.  We  have  demonstrated  tolerability  and  characterized  the  favorable 
pharmacokinetic  profile  of  Immunosynthen ADCs  in  non-human  primates  after  multiple  intravenous  doses  and  at  exposures 
significantly higher than those required for robust efficacy in mice. 

Immunosynthen  ADCs  have  been  designed  to  overcome  the  limitations  of  free  STING  agonists  and  to  offer  a  highly 
differentiated approach from other innate immune activators due to the following: 

•  Non-Cell Permeable STING Agonist ImmunoLock Payload: Our novel and proprietary payload has very low cell 

permeability, remaining in the cell to which it is delivered by the antibody, where it can exert its effect. 

9 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
•  Enhanced Pharmacokinetic Properties: The prolonged pharmacokinetics of ADCs and active transport into tumor 
cells and tumor-resident immune cells can overcome pharmacokinetic and permeability issues of the free agonists, 
resulting in more robust and sustained activation of the innate immune response in the tumor. 

•  Targeted Activation in Two Cell Types: Because STING, unlike other innate immune pathways, can be activated in 
tumor cells and tumor-resident immune cells, target-dependent delivery can result in innate immune activation of both 
cell types, providing potent and robust anti-tumor responses and the induction of immunological memory. 

Together  these  features  have  the  potential  to  improve  the  applicable  therapeutic  index  by  selectively  activating  the  innate 
immune  system  in  the  tumor  environment  and  minimizing  activation  in  other  tissues.  We  are  building  a  pipeline  of 
Immunosynthen ADC  candidates  applicable  to  a broad  range  of  clinical  indications.  In January 2023,  we  initiated  a Phase  1 
clinical trial of our first Immunosynthen ADC product candidate, XMT-2056, which targets a novel epitope of HER2. 

Our product candidates 

We are leveraging our platforms to develop a robust pipeline of product candidates that have the potential to become clinically 
meaningful  cancer  therapies.  Our  pipeline  strategy  focuses  on  targets  that  have  been  biologically  validated  (either  through 
ADCs  or  other  modalities),  where  the  advantages  of  our  platforms  may  lead  to  clinically  superior  therapeutic  benefits  and 
where we have the potential to achieve first-in-class status by pursuing fast-to-market development strategies. Our lead product 
candidate,  UpRi,  is  currently  being  evaluated  in  three  clinical  trials:  UPLIFT,  UP-NEXT  and  UPGRADE-A.  We  are  also 
advancing XMT-1660, a B7-H4-targeted Dolasynthen ADC, and XMT-2056, our first Immunosynthen ADC targeting a novel 
epitope  of  HER2,  both  of  which  are  currently  in  Phase  1  clinical  trials.  In  addition,  our  collaborators  have  multiple  ADC 
product candidates in various stages of  development. In  May  2022,  we decided to  discontinue development  of  XMT-1592,  a 
Dolasynthen ADC targeting NaPi2b that had been in a Phase 1 dose exploration trial in patients with ovarian cancer and non-
small cell lung cancer, or NSCLC, and we closed this company-sponsored trial in September 2022. 

UpRi: our NaPi2b-targeted Dolaflexin ADC 

UpRi, a first-in-class ADC targeting the sodium-dependent phosphate transport protein NaPi2b, utilizes the Dolaflexin platform 
to deliver about 10 DolaLock payload molecules per antibody. We believe the NaPi2b antigen is broadly expressed in ovarian 
cancer  and  other  cancers  with  limited  expression  in  normal  tissue.  NaPi2b  is  a  member  of  the  SLC34  family  of  sodium-
dependent transporters and plays an important role in maintaining phosphate homeostasis. We initiated a Phase 1/2 clinical trial 
of  UpRi  in  December  2017  with  the  primary  objectives  of  determining  the  recommended  Phase  2  dose  and  characterizing 
UpRi’s efficacy, safety and tolerability. Our secondary objective was to  assess  the  potential correlation of NaPi2b biomarker 
expression  and  efficacy.  The  dose  escalation  portion  of  the  trial  established  a  dose  of  43  mg/m2,  up  to  a  maximum  of 
approximately 80 mg, as the maximum tolerated dose. The expansion portion of the trial evaluated two dose levels, 36 mg/m2 
and 43 mg/m2, up to a maximum of approximately 80 mg. 

There are currently no tests approved by the FDA to measure NaPi2b expression on tumor cells. While our initial clinical trials 
have  not  prospectively  identified  patients  with  NaPi2b-expressing  tumors,  our  development  plan  for  UpRi  includes  the 
development of a proprietary immunohistochemistry assay to measure NaPi2b expression in tumors. Based on our retrospective 
evaluation of tumors collected in the dose escalation and expansion portions of our initial UpRi Phase 1 trial, our evaluation of 
patient tissue bank materials and other published data we believe that high NaPi2b expression is present in at least a majority of 
ovarian  cancer  patients.  We  intend  to  continue  developing  our  assay  in  order  to  confirm  our  estimates  of  the  prevalence  of 
NaPi2b expression in our target patient populations while evaluating the correlation of those expression levels with the efficacy 
observed  in  such  patients. We  are  currently  collaborating  with  a  third  party  to  create  and  obtain  regulatory  approval  for  our 
assay as a commercial companion or complementary diagnostic, and we expect that the third party would seek such approval 
simultaneously with our submission of a BLA, if any, for UpRi around the end of 2023. We are using and expect to continue to 
use the assay to evaluate Tumor Proportion Score of greater than or equal to 75%, TPS75, to identify patients with tumors that 
have high NaPi2b tumor expression and to help us enrich our data analyses based on biomarker expression. We refer to patients 
with cancers with TPS75 as “NaPi2b positive.” 

Over  the  course  of  2020,  we presented  early  Phase  1  UpRi  clinical  data,  including  presentations  at  the American  Society  of 
Clinical Oncology and the European Society for Medical Oncology and in company presentations to investors. These data were 
from the dose escalation and expansion portions of our UpRi Phase 1 trial, and they demonstrated encouraging clinical activity 
in heavily pretreated patients with a safety profile differentiated from those of first-generation ADCs. In August 2020, the FDA 
granted Fast Track Designation for UpRi for the treatment of patients with platinum-resistant high-grade serous ovarian cancer 
who have received up to three prior lines of systemic therapy or patients who have received four prior lines of systemic therapy 
regardless  of  platinum  status.  In  January  2021,  September  2021  and  March  2022,  we  provided  interim  clinical  data  updates 
from our expansion cohort. The interim data presented in September 2021 and March 2022 was based on approximately 100 

10 

 
 
 
 
 
 
ovarian cancer patients. All of the data from these patients were from our ongoing Phase 1/2 clinical trial. These data supported 
UpRi’s  clinically  meaningful  activity  in  heavily  pretreated  ovarian  cancer  patients  with  an  ORR  of  approximately  34%, 
including  complete  responses,  in  evaluable  patients  with  NaPi2b  positive  tumors.  The  data  also  showed  that  UpRi  was 
generally well tolerated without the severe toxicities commonly seen with other ADCs such as neutropenia, ocular toxicities, or 
peripheral neuropathy. The most common grade 3 or higher adverse events reported in this heavily pretreated trial population 
included  fatigue  and  transiently  increased  aspartate  aminotransferase.  Other  adverse  events  of  clinical  interest  included 
infrequent, generally low-grade pneumonitis that generally resolves with dose reduction, delay, discontinuation and treatment 
with  steroids.  Based  on  these  safety  and  efficacy  data  and  our  population  pharmacokinetics  analyses  of  the  overall  group  of 
approximately  200  patients  administered  UpRi  as  of  the  data  cut  off,  we  determined  that  the  Phase  2  recommended  dose  of 
UpRi is 36 mg/m2, up to a total dose of approximately 80 mg. This is the dose that we are currently evaluating in UPLIFT. 

In April 2021, we initiated UPLIFT to enroll patients with platinum-resistant ovarian cancer who had been treated with one to 
four  prior  lines  of  therapy,  without  regard  to  NaPi2b  expression.  In  this  trial,  we  are  seeking  to  confirm  the  potentially 
predictive role of the Napi2b biomarker retrospectively using our novel diagnostic assay to identify NaPi2b positive patients. 
Patients who had been treated with three to four prior lines of therapy were able to enroll without prior bevacizumab treatment, 
accommodating differences in bevacizumab use in early disease. Additionally, patients who had experienced grade 1 or grade 2 
neuropathy  on  previous  treatments  were  eligible  to  enroll  in  UPLIFT.  The  primary  endpoint  is  ORR  in  the  NaPi2b  positive 
patient population, and the secondary endpoints are ORR in the overall population, duration of response and safety. In October 
2022,  we  completed  the  enrollment  of  approximately  270  patients  in  UPLIFT  at  sites  in  the  United  States,  Europe  and 
Australia. We expect to announce top-line data from UPLIFT in mid-2023 following the major oncology conferences scheduled 
for June. If we achieve positive results from UPLIFT, we believe that the trial may enable us to submit a BLA for UpRi for the 
treatment of patients with platinum-resistant ovarian cancer with one to four prior lines of therapy under the FDA's accelerated 
approval pathway around the end of 2023. 

In July 2021, we initiated UPGRADE-A, a Phase I open-label clinical trial in which we are evaluating the combination of UpRi 
and  carboplatin,  a  standard  platinum  chemotherapy  used  to  treat  patients  with  platinum-sensitive  ovarian  cancer,  in  patients 
with  platinum-sensitive  high-grade  serous  ovarian  cancer  following  one  to  three  prior  lines  of  treatment.  Patients  in  the  trial 
receive combination treatment every four weeks for six cycles followed by UpRi as a single-agent maintenance therapy. While 
patients in the trial are not preselected for NaPi2b-positive status, we are conducting a retrospective assessment of expression. 
We have completed the dose escalation portion of the trial, which investigated carboplatin combined with UpRi doses up to 36 
mg/m2. There were no dose-limiting toxicities at any dose level. In January 2023, we initiated the dose expansion portion of 
UPGRADE-A,  in  which  we  are  investigating  a  30mg/m2  dose,  up  to  a  maximum  of  66  mg,  of  UpRi.  We  expect  to  report 
interim  data  from  UPGRADE-A  in  the  second  half  of  2023.  We  believe  data  from  UPGRADE-A  will  inform  further 
development  of  UpRi  both  in  combination  with  carboplatin  and  in  combination  with  other  therapies  used  in  patients  with 
platinum-sensitive ovarian cancer, which we may explore in a series of UPGRADE trials. 

We continue to enroll patients in our UP-NEXT clinical trial, for which we initiated patient dosing in late 2022. The design of 
UP-NEXT was informed by discussions with the FDA and the Committee for Medicinal Products for Human Use, or CHMP. 
UP-NEXT is enrolling recurrent platinum-sensitive ovarian cancer patients who have achieved an objective response or stable 
disease after platinum therapy. Eligible patients with BRCA mutation must have received prior treatment with poly-adenosine 
diphosphate  ribose  polymerase,  or  PARP,  inhibitor  therapy. Additionally,  eligible  patients  must  have  NaPi2b  positive  tumor 
expression. Due to the lack of a standard of  care for patients in the recurrent ovarian cancer  maintenance setting,  the trial  is 
randomized against placebo and is investigating a 30 mg/m2 dose, up to a maximum of 66 mg, of UpRi. We believe that if the 
data  from  the  trial  is  positive,  UP-NEXT  could  serve  as  a  post-approval  confirmatory  trial  in  the  United  States,  support 
potential approvals outside of the United States and support the expansion of UpRi into earlier lines of therapy. 

XMT-1660: our B7-H4-targeted Dolasynthen ADC candidate 

XMT-1660  is  our  B7-H4-targeted  ADC  created  with  our  Dolasynthen  platform  and  equipped  with  our  DolaLock  payload 
designed  for  differentiated  tolerability  without  severe  neutropenia,  peripheral  neuropathy  or  ocular  toxicities  associated  with 
other anti-tubulin payloads. We believe the expression profile of B7-H4, is well suited for our unique DolaLock payload. B7-
H4 can be expressed on tumor cells and on immunosuppressive tumor associated macrophages, or TAMs, which may lead to 
additional processing of the ADC and more payload in the tumor environment. We believe DolaLock’s direct cytotoxic effect, 
as  well  as  its  immunostimulatory  effect  through  immunogenic  cell  death  and  dendritic  cell  activation,  are  well  suited  to  the 
biology  of  the  B7-H4  target. We  have  generated  favorable  preclinical  efficacy  data  and  non-human  primate  tolerability  data 
with  Dolasynthen  ADCs  targeting  B7-H4  with  precise  DARs  of  2  and  6.  We  selected  the  DAR6  variant  based  on  these 
preclinical  data,  as  well  as  a  comparison  to  preclinical  data  generated  with  a  B7-H4  Dolaflexin  ADC  with  a  DAR  of 
approximately 12. We believe that targeting B7-H4 with XMT-1660 provides significant opportunities for development in areas 
of  high unmet  need. We  are currently  investigating  XMT-1660  in  a  multicenter  Phase  1  clinical  trial  in  patients  with  breast, 
endometrial and ovarian cancers.  

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XMT-2056: our First Immunosynthen ADC candidate 

XMT-2056  is  our  first  Immunosynthen  STING-agonist  ADC.  As  described  above,  the  therapeutic  rationale  of  an 
Immunosynthen ADC is to selectively deliver the STING agonist to tumor cells and tumor-resident immune cells in a target-
dependent  manner  while  avoiding  delivery  to  healthy  tissues.  XMT-2056  is  designed  to  offer  a  differentiated  and 
complementary  therapeutic  approach  to  the  treatment  of HER2-expressing  tumors.  XMT-2056  targets  a  novel  HER2  epitope 
that  is  distinct  from  the  epitopes  targeted  by  trastuzumab  or  pertuzumab,  providing  an  opportunity  for  development  as  a 
monotherapy as well as in combination with well-established or investigational anti-HER2 agents. In preclinical studies, XMT-
2056  was  generally  well-tolerated  in  non-human  primate  studies  with  no  adverse  findings  in  clinical  pathology  or 
histopathology after repeat doses as high as 36 mg/kg. In January 2023, we initiated a multicenter Phase 1 open-label clinical 
trial of XMT-2056 in patients with advanced/recurrent solid tumors expressing HER2, including breast, gastric, colorectal and 
NSCLC. 

Ovarian cancer unmet need and epidemiology 

According  to  the  World  Cancer  Research  Fund  International,  in  2020,  the  incidence  of  ovarian  cancer  worldwide  was 
approximately 314,000, with the disease causing an estimated 207,000 deaths. With a U.S. incidence of approximately 20,000 
and  mortality  of  13,000  in  2022  according  to  the  National  Cancer  Institute  Surveillance,  Epidemiology  and  End  Results 
Program, ovarian cancer was the second most common gynecologic malignancy and the most common cause of gynecologic 
cancer death in the United States. Diagnosis is made histologically, and evaluation is commonly performed following surgical 
removal of an ovary or fallopian tube or biopsies of the peritoneum. The  ovarian  cancer standard of  care is  characterized  by 
initial  surgery  followed  by  platinum-containing  chemotherapy  followed  by  either  observation  or  maintenance  treatment. 
Approximately 80% of ovarian cancer patients typically relapse following initial treatment. Subsequent treatment depends on 
the duration of response to initial platinum treatment. Ovarian cancer patients who progress within six months of completion of 
platinum-based therapy are considered to have platinum-resistant disease. Unmet medical need is significant for patients with 
platinum-resistant  ovarian  cancer  as  treatment  options  are  mainly  limited  to  single-agent  chemotherapies  such  as  pegylated 
liposomal  doxorubicin,  topotecan  or  paclitaxel.  Multiple  Phase  3  trials  of  single  agent  chemotherapies  in  patients  with 
platinum-resistant  disease  and  one  to  three  prior  therapies  have  exhibited  an  overall  response  rate  of  4-12%  and  median 
progression-free  survival  of  3-4  months.  In  2022,  mirvetuximab  soravtansine  was  approved  under  an  accelerated  approval 
pathway in the United States for patients with FRα positive, platinum-resistant ovarian cancer who have received one to three 
prior systemic treatment regimens. Only a minority  of ovarian  cancer patients  are  FRα positive,  and  the unmet need remains 
high for the majority of platinum-resistant ovarian cancer patients.  In  addition,  mirvetuximab  soravtansine is  associated with 
significant toxicities, including a boxed warning for ocular toxicity. 

With targeted agents approved in platinum-resistant disease increasingly being prescribed in earlier lines of therapy, the unmet 
need  in  later  lines  is  expected  to  remain  severe.  Bevacizumab  in  combination  with  chemotherapy  is  indicated  in  the  United 
States to treat a subset of platinum-resistant ovarian cancer patients with no more than two prior therapies, but it is not always 
well-tolerated  and  has  not  shown  an  overall  survival  benefit.  Use  of  bevacizumab  in  combination  with  platinum-containing 
chemotherapy  in  the  frontline  and  platinum-sensitive  recurrent  settings  means  an  increasing  number  of  platinum-resistant 
patients are pre-treated with bevacizumab. Previously, PARP inhibitors had been approved for heavily pretreated ovarian cancer 
including  platinum-resistant  disease.  Recently,  the  indications  for  PARP  inhibitors  in  the  United  States  were  changed  so  that 
they  are  no  longer  approved  for  use  in  platinum-resistant  ovarian  cancer.  They  are  currently  approved  only  for  use  as 
maintenance treatment in the frontline or platinum-sensitive ovarian cancer setting, in patients who are responding to platinum-
based chemotherapy. In addition, they are increasingly restricted to use in a subset of patients with cancers harboring BRCA1 
and BRCA2 mutations in the recurrent setting.  

Breast cancer unmet need and epidemiology 

Worldwide, breast cancer was the most common cancer, with an incidence of approximately 2.3 million and estimated 685,000 
deaths in 2020. The U.S. incidence was approximately 288,000 new cases  with  approximately 43,250  deaths  in  2022. While 
patients  with  localized  disease  typically  have  a  relatively  good  prognosis,  the  five-year  survival  of  patients  with  distant 
metastasis  is  only  29%.  There  are  four  main  female  breast  cancer  subtypes,  which  are,  in  order  of  prevalence:  Hormone 
Receptor,  or  HR,  positive  (HR+)/HER2  negative  (HER2-),  which  is  referred  to  as  Luminal  A;  HR  negative  (HR-)/HER2-, 
which  is  referred  to  as  Triple  Negative;  HR+/HER2  positive  (HER+),  which  is  referred  to  as  Luminal  B;  and  HR-/HER2+, 
which  is  referred  to  as  HER2-enriched.  This  categorization  of  patients  is  being  revisited  given  the  approval  of  trastuzumab 
deruxtecan for the treatment of HER2-low metastatic  breast cancer in  2022. Treatment choice  is  driven  by both  subtype and 
stage of disease. Surgical resection offers the best opportunity for long-term survival and cure in patients with resectable early-
stage  disease.  Some  patients  receive  radiation  therapy  and/or  systemic  therapy  post-surgery,  with  treatment  choice  driven  by 
cancer subtype.  

12 

 
 
 
 
 
Systemic therapy is the mainstay of treatment for metastatic breast cancer. Once again, the treatment choice is determined by 
cancer subtype and by what treatments patients have received previously. The primary treatment option for patients who are 
HR+ is endocrine therapy, including aromatase inhibitors. Patients who are HER2+ are usually treated with HER2-targeting 
agents such as trastuzumab and pertuzumab, among others. In 2022, the HER2 targeting therapy trastuzumab deruxtecan was 
approved for the treatment of patients with HER2-low metastatic breast cancer. Other targeted agents that are used in metastatic 
breast cancer include CDK4/6 inhibitors, mTOR inhibitors, PARP inhibitors, phosphoinositide 3-kinase, or PI3K, inhibitors, 
immunotherapy and ADCs. Patients can also receive chemotherapies, alone or in combination with other agents. In addition, a 
number of new therapeutic options are under clinical investigation. Despite the availability of these treatment options, outcomes 
in metastatic breast cancer continue to be poor, and new treatments that improve survival and quality of life are urgently 
needed. 

Strategic Collaborations 

We view business development as a core pillar of our overall corporate strategy, and our platforms and product candidates allow 
us to consider multiple potential types of strategic collaborations. We believe that our ADC platforms have broad applicability 
across a number of targets, allowing us to consider collaborations in which a partner provides proprietary antibodies for a select 
number  of  targets  and  we  utilize  our  platforms  to  discover  novel  ADC  product  candidates.  Under  these  collaboration 
agreements, we own the rights to any improvements to our ADC platform(s). For instance, we have entered into two discovery 
collaborations  with  Merck  KGaA  and  a  separate  discovery  collaboration  with  Janssen.  We  believe  platform-based 
collaborations  allow  us  to  leverage  the  potential  of  our  platforms,  provide  near-term  capital  and  help  us  potentially  bring 
important new therapeutic options to patients. 

We also have internally developed ADC product candidates that allow us to consider arrangements in which a collaborator may 
assume certain preclinical, clinical and/or commercial responsibilities. For instance, we have granted GSK an exclusive option 
for an exclusive global license to co-develop and commercialize XMT-2056. We believe product-focused collaborations could 
provide  near-term  funding,  allow  us  to  advance  and  broaden  preclinical,  clinical  or  commercial  development  efforts  beyond 
those we could independently, and potentially bring new therapeutic options to patients. 

2022 Merck KGaA Collaboration 

In December 2022, we entered into a collaboration and commercial license agreement with Ares Trading S.A., or MRKDG, a 
wholly  owned  subsidiary  of  Merck  KGaA,  or  the  2022  Merck  KGaA  Agreement.  Pursuant  to  the  2022  Merck  KGaA 
Agreement,  we  will  grant  MRKDG  an  exclusive  license  to  use  our  proprietary  technology  to  develop,  manufacture  and 
commercialize  Immunosynthen ADCs  directed  to  up  to  two  specific  target  antigens,  or  the  Designated  Targets,  selected  by 
MRKDG  within  a  certain  period  following  the  effectiveness  of  the  2022  Merck  KGaA  Agreement.  MRKDG  has  already 
selected the first Designated Target under the 2022 Merck KGaA Agreement. 

Under  the  terms  of  the  2022  Merck  KGaA Agreement,  the  parties  will  conduct  up  to  two  research  programs.  Each  research 
program will involve activities related to Immunosynthen ADCs for a selected Target (with each such ADC developed under the 
2022 Merck KGaA Agreement being a Licensed ADC) until the submission of an investigational new drug application, or IND, 
(or foreign equivalents) for a Licensed ADC directed at such Designated Target, or each an MRKDG Licensed Product, or until 
the  earlier  expiration  of  the  defined  research  period.  Each  research  program  will  follow  a  research  plan  agreed  between  the 
parties. For each Designated Target, MRKDG is responsible for providing up to a specified number of antibodies against such 
Designated  Target,  and  we  are  responsible  for  conjugating  such  antibodies  using  our  Immunosynthen  platform  to  create 
Licensed  ADCs.  Each  party  will  be  responsible  for  their  own  costs  under  the  research  programs.  In  addition,  we  will  be 
responsible  for  certain  chemistry,  manufacturing  and  controls  development  and  certain  manufacturing  activities  for  the 
Licensed  ADCs,  up  to  and  including  manufacturing  of  drug  substance  for  Licensed  ADCs  to  be  used  in  certain  preclinical 
studies and clinical trials, in each case at MRKDG’s expense, some of which will be prepaid by MRKDG. Except as provided 
above, MRKDG is solely responsible for in vitro and in vivo characterization of any Licensed ADCs, other preclinical work, 
and all clinical development and potential commercialization activities relating to any resulting MRKDG Licensed Products. 

Under  the  terms  of  the  2022  Merck  KGaA Agreement,  we  received  an  upfront  payment  of  $30.0  million  in  February  2023. 
Certain development and regulatory milestones will be  payable  by  MRKDG  to  us for the  research  programs,  including  upon 
certain  discovery  milestones,  initiation  of  certain  clinical  trials,  and  regulatory  approval  of  MRKDG  Licensed  Products  in 
certain geographies, with an aggregate total of up to $200 million in the event MRKDG advances MRKDG Licensed Products 
directed to both Designated Targets to regulatory approval. 

In the event the commercialization of the MRKDG Licensed Product results in commercial sales, commercial milestones will 
be payable by MRKDG to us for each program upon the achievement of specified aggregate sales thresholds for an MRKDG 
Licensed  Product  for  the  applicable  Designated  Target,  with  an  aggregate  total  of  up  to  $600  million  in  the  event  MRKDG 
Licensed Products directed to both Designated Targets are commercialized by MRKDG. In addition, we are eligible to receive 

13 

 
 
 
 
 
 
 
 
 
tiered royalties at percentages ranging from the single digits to the low double digits on future net sales of MRKDG Licensed 
Products. 

MRKDG’s royalty obligations continue with respect to each country and each MRKDG Licensed Product until the latest of (i) 
the date on which such MRKDG Licensed Product is no longer covered by certain intellectual property rights in such country, 
(ii) the 10th anniversary of the first commercial sale of such MRKDG Licensed Product in such country and (iii) the expiration 
of marketing or data exclusivity for such MRKDG Licensed Product in such country. 

Under the terms of the 2022 Merck KGaA Agreement, subject to certain exceptions and for an agreed period of time, we will 
not,  either  ourselves  or  through  third  parties,  research,  develop,  manufacture  or  commercialize  other  ADCs  utilizing  our 
Immunosynthen platform that are directed to the Designated Targets. We and MRKDG  will form a joint research committee, 
joint manufacturing committee, and joint intellectual property committee responsible for coordinating activities pursuant to the 
2022 Merck KGaA Agreement. 

Each party has the right to sublicense its rights under the 2022 Merck KGaA Agreement subject to certain conditions. The 2022 
Merck KGaA Agreement will continue, unless earlier terminated, until the expiration of the last-to-expire royalty term for the 
last MRKDG Licensed Product or, if MRKDG does not advance any MRKDG Licensed Products, upon the expiration of the 
last-to-expire research program. MRKDG may, at its convenience, terminate the 2022 Merck KGaA Agreement in its entirety or 
on a Designated Target-by-Designated Target basis upon certain notice  to us. Either  we  or  MRKDG may  terminate the 2022 
Merck KGaA Agreement for the other party’s insolvency or certain  uncured breaches. In lieu of terminating the 2022 Merck 
KGaA Agreement, in the event MRKDG is entitled to terminate the 2022 Merck KGaA Agreement due to our uncured material 
breach, MRKDG may make an election, as its sole and exclusive remedy with respect to our applicable material breach of the 
2022 Merck KGaA Agreement, to invoke a specified financial penalty impacting one or more future payments that may become 
payable to us following such uncured material breach. We may terminate the 2022 Merck KGaA Agreement with respect to a 
Designated Target in the event of certain failures by MRKDG to progress the corresponding research program. Additionally, we 
may terminate the 2022 Merck KGaA Agreement if MRKDG or any of its sublicensees or affiliates challenge, subject to certain 
exceptions, the validity, enforceability, of patentability of certain of our patents. 

GSK Collaboration 

In August 2022, we entered into a collaboration, option and license agreement with GSK, or the GSK Agreement, to provide 
GSK  with an exclusive option to obtain an exclusive global  license to  co-develop  and  to  commercialize  products containing 
XMT-2056, or Licensed Products, exercisable within a specified time period, or the Option Period, after we deliver to GSK a 
data  package,  or  the  Option  Data  Package,  resulting  from  completion  of  dose  escalation  with  enrichment  for  breast  cancer 
patients in a Phase 1 single-agent clinical  trial of XMT-2056.  GSK’s  exercise of  the Option may require clearance under the 
Hart-Scott-Rodino Antitrust Improvements Act of 1976, or HSR Clearance. Upon GSK’s exercise of the Option following any 
applicable  HSR  Clearance,  or  the  GSK  Option  Exercise,  GSK  is  obligated  to  pay  us  an  option  exercise  payment  of  $90.0 
million. 

We will lead research and development activities related to our XMT-2056 program prior to the GSK Option Exercise, if any, 
and we are obligated to use commercially reasonable efforts to generate the Option Data Package by an agreed time. Prior to the 
GSK Option Exercise, we will be responsible for the costs of manufacturing, research and early clinical development activities 
related to the XMT-2056 program. 

Following  the  GSK  Option  Exercise,  if  any,  GSK  may  elect  to  manufacture  XMT-2056,  and  we  and  GSK  will  co-develop 
XMT-2056  in  accordance  with  a  joint  development  plan  to  be  established  by  the  parties  and  aimed  at  approval  of  Licensed 
Products  in  the  United  States  and  the  European  Union,  with  GSK  being  responsible  for  the  majority  of  the  development 
activities  and  costs.  GSK  will  be  responsible  for  all  of  the  development  costs  aimed  solely  at  gaining  approval  outside  the 
United States and the European Union. Subject to certain exceptions set forth in the GSK Agreement, our aggregate share of 
U.S.-  and  E.U.-focused  development  costs  pursuant  to  this  cost-sharing  arrangement  is  capped  at  a  fixed  amount,  or  the 
Mersana Development Cost Cap. We may also, subject to certain limitations provided in the GSK Agreement, elect to opt out of 
sharing  in  development  costs  for  certain  later-stage  clinical  trials  of  Licensed  Products  requested  by  GSK,  subject  to  certain 
payment  obligations  in  the  event  that  data  from  any  such  later-stage  clinical  trial  for  which  we  have  opted  out  of  sharing  in 
development costs results in certain marketing approvals for a Licensed Product in the United States or European Union, or a 
Deemed  Buy-In  Payment. Any  development  costs  in  excess  of  the  Mersana  Development  Cost  Cap,  including  any  amounts 
arising from any Deemed Buy-In Payments, will be borne by GSK unless and until we exercise our Profit Share Election (as 
defined below). Development costs in excess of the Mersana Development Cost Cap will accrue interest at a variable rate equal 
to  the  prime  rate  plus  a  specified  margin  and  will  later  either  be  repaid  by  us  or  offset  against  future  regulatory  and  sales 
milestone or royalty payments that may become due to us. If we exercise our Profit Share Election, the Mersana Development 
Cost Cap will no longer apply, we must pay any then-outstanding excess plus accrued interest, and we shall continue to share in 
further U.S.- and E.U.-focused development costs. 

14 

 
 
 
 
 
 
 
 
Following the GSK Option Exercise, if any, we will have  the  option, during  a specified time  period following our receipt  of 
certain later-stage clinical data and other data and information from GSK, to elect to receive (or bear) a specified share of U.S. 
profits (or losses) for any Licensed Products, or the Profit Share Election. Additionally, if we exercise our Profit Share Election, 
we may also simultaneously elect to co-promote any  Licensed  Products in the United States. The co-promotion  arrangement 
may be terminated by either party, notwithstanding the continued effectiveness of the rest of the GSK Agreement, in the event 
of certain breaches by the other party, or by GSK, in the event of certain specified changes of control of Mersana. In addition, in 
the event of certain specified changes of control of Mersana, GSK can prohibit us from executing development activities that 
are initiated under the GSK Agreement following such change of control. 

We received an upfront payment of $100 million from GSK for the Option. We are eligible to receive up to $30 million upon 
satisfaction  of  early  clinical  development  milestones  that  may  occur  prior  to  the  GSK  Option  Exercise.  Subject  to  the  GSK 
Option  Exercise,  if  we  do  not  exercise  our  Profit  Share  Election,  we  will  be  eligible  to  receive  additional  future  clinical 
development and regulatory milestone payments of up to $592 million, commercial milestone payments of up to $652 million 
and tiered double-digit royalties up to the mid-twenty percent range on global sales of Licensed Products, if approved, subject 
to customary reductions. If we exercise our Profit Share Election, we will, in lieu of the foregoing regulatory and commercial 
milestone amounts, be eligible to receive reduced regulatory and commercial milestone payments and reduced royalty rates on 
sales outside of the United States. Additionally, whether or not we exercise our Profit Share Election, GSK will be responsible 
for certain milestone payments or royalties due to specified third parties with which we currently have agreements that relate to 
the XMT-2056 program. 

GSK’s royalty obligations continue with respect to  each  country  and each  Licensed  Product until  the latest of  (i) the date on 
which  such  Licensed  Product  is  no  longer  covered  by  certain  intellectual  property  rights  in  such  country,  (ii)  the  12th 
anniversary  of  the  first  commercial  sale  of  such  Licensed  Product  in  such  country  and  (iii)  the  expiration  of  regulatory 
exclusivity for such Licensed Product in such country. 

Under the terms of the GSK Agreement, subject to certain exceptions and for an agreed period of time, we and GSK will not, 
either directly or through third parties, develop or commercialize other products or compounds that (a) comprise or contain an 
ADC that is conjugated with a STING agonist and (b) are directed to HER2. In addition, we have granted GSK a right of first 
negotiation for future ADCs that are conjugated to payloads other than STING agonists and directed to HER2. Following the 
GSK  Option  Exercise,  if  any,  we  and  GSK  will  form  a  joint  steering  committee,  joint  development  committee,  joint 
manufacturing  committee,  joint  commercialization  committee,  and  financial  working  group  responsible  for  coordinating  all 
activities  under  the  GSK Agreement,  with  GSK  having  final  decision-making  authority  over  most  issues,  subject  to  certain 
enumerated exceptions. 

The GSK Agreement will terminate at the end of the Option Period if GSK does not exercise its Option. If GSK exercises its 
Option but we do not obtain HSR Clearance within specified time periods following the latest date on which the parties have 
made their respective applicable filings related to such HSR Clearance, each party has a right to terminate the GSK Agreement. 
In  the  event  of  the  GSK  Option  Exercise,  the  GSK  Agreement  will  continue  in  effect  on  a  Licensed  Product-by-Licensed 
Product and country-by-country basis until the expiration of the obligation to make payments under the GSK Agreement with 
respect to such Licensed Product in such country, unless earlier  terminated by  either  party  pursuant  to the terms of the GSK 
Agreement.  Either  we  or  GSK  may  terminate  the  GSK  Agreement  for  the  other  party’s  insolvency,  and  each  party  may 
terminate the GSK Agreement for certain uncured breaches by the other party. In lieu of terminating the GSK Agreement, in the 
event of certain uncured material breaches by us, GSK may make a one-time election, in addition to other contractual remedies 
available at law or in equity, to invoke a specified financial penalty impacting one or more future payments that may become 
payable to the Company following such uncured material breach. We may terminate GSK’s license to certain of our patents if 
GSK  or  any  of  its  sublicensees  or  affiliates  challenge  the  validity,  enforceability,  of  patentability  of  such  patents.  GSK  may 
terminate the GSK Agreement for convenience upon certain notice to us. 

Janssen Collaboration  

In  February  2022,  we  entered  into  a  research  collaboration  and  license  agreement  with  Janssen,  or  the  Janssen Agreement, 
pursuant to which we granted Janssen an exclusive license to use our proprietary Dolasynthen platform and other technology to 
develop,  manufacture  and  commercialize  antibody-drug  conjugates  directed  to  up  to  three  targets  selected  by  Janssen.  Our 
responsibilities are to perform bioconjugation activities to create ADCs for Janssen based on antibodies provided by Janssen. 
We will also perform certain chemistry, manufacturing and controls development and early stage manufacturing activities for 
ADCs  that  Janssen  progresses  through  development,  up  to  and  including  the  manufacturing  of  clinical  drug  substance,  at 
Janssen’s  cost.  Except  with  respect  to  this  limited  manufacturing,  Janssen  will  be  responsible  for  the  further  development, 
manufacturing and commercialization of the ADCs developed under the Janssen Agreement, including obtaining any necessary 
regulatory approvals, at Janssen’s cost. 

15 

 
 
 
 
 
 
 
 
Under the terms of the Janssen Agreement, we received an upfront payment of $40 million. Certain development and regulatory 
milestones will also be payable by Janssen for the research programs, including upon certain discovery milestones, initiation of 
certain clinical trials, and regulatory approval of certain licensed products in certain geographies, with an aggregate total of up 
to $501 million in the event ADCs directed to all three targets are advanced by Janssen. In the event the ADCs developed by 
Janssen are commercialized, we are eligible to receive certain commercial milestones for each program upon the achievement 
of  specified  aggregate  sales  thresholds  based  on  all  ADCs  for  an  applicable  target,  with  an  aggregate  total  of  up  to 
approximately $530 million in the event ADCs directed to all three targets are commercialized by Janssen. In addition, we are 
eligible to receive tiered royalties at percentages ranging from the mid-single digits to the low-double digits on future net sales 
of ADCs. 

The Janssen Agreement will remain in effect, unless earlier terminated, until the expiration of the last-to-expire royalty term for 
the  last ADC. Royalty term means on an ADC-by-ADC  and  country-by-country basis, the  period  commencing upon the  first 
commercial sale of an ADC in such country and ending upon the latest to occur of: (a) the date of expiration of the last royalty-
bearing patent claim with  respect to such ADC in such  country;  (b) the expiration of regulatory exclusivity  for  such ADC in 
such country, if any; and (c) the tenth (10th) anniversary of the first commercial sale of such ADC in such country. Upon the 
expiration of the royalty term with respect to an ADC  in  a  country, Janssen’s  license  becomes a perpetual, irrevocable,  non-
exclusive,  fully-paid  and  royalty-free  right  and  license,  with  the  right  to  grant  sublicenses,  under  the  relevant  platform 
technology and our interest in any joint technology to develop, manufacture, commercialize and otherwise exploit such ADC in 
such country. 

2014 Merck KGaA Collaboration 

In June 2014, we entered into a collaboration and commercial license agreement with Merck KGaA, or the 2014 Merck KGaA 
Agreement,  under  which  we  formed  a  strategic  relationship  with  Merck  KGaA  because  of  their  expertise  in  oncology  drug 
development.  Under  the  2014  Merck  KGaA Agreement,  we  are  responsible  for  generating ADC  product  candidates  against 
Merck KGaA-selected target antigens. Merck KGaA received rights to select up to six target antigens, of which it has selected 
all six. Merck KGaA is responsible for generating antibodies against the target antigens, and we are responsible for generating 
Dolaflexin and conjugating this to such antibodies  to create  the ADC  product  candidates. With  respect to  each  target  antigen 
selected by Merck KGaA, we granted Merck KGaA an exclusive, worldwide license under certain of our Fleximer ADC-related 
patents  and  know-how  to  develop,  manufacture  and  commercialize ADC  product  candidates  directed  to  such  target  antigen. 
Merck  KGaA  is  then  responsible  for  the  further  development  and  commercialization  of  these  ADC  product  candidates.  In 
addition, if Merck KGaA advances candidates, we are responsible for manufacturing these ADC product candidates for good 
laboratory practices toxicology studies and Phase 1 clinical trials at Merck KGaA’s expense and Merck KGaA is responsible for 
all further manufacture of these ADC product candidates. Merck  KGaA is required  to pay  its  own  costs in  the  development, 
commercialization and manufacture of these ADC product candidates and to reimburse us for our costs incurred in performing 
our research activities under this agreement. 

Through December 31, 2022, we have received an upfront payment of $12 million and milestone payments of $3 million under 
the 2014 Merck KGaA Agreement. If products are successfully developed and commercialized against all six target antigens, 
we  would  be  entitled  to  receive  future  development,  regulatory  and  commercial  milestones  of  up  to  $777 million.  We  are 
entitled to receive tiered royalties in the low- to mid-single digit percentages on net sales of products targeting Merck KGaA’s 
target antigens during the applicable royalty term if products are successfully developed and commercialized by Merck KGaA 
under the 2014 Merck KGaA Agreement. 

Unless  earlier  terminated,  the  2014  Merck  KGaA  Agreement  will  expire  upon  the  expiration  of  the  last  royalty  term  for  a 
product under the agreement in all countries or, if Merck KGaA does not designate any ADC product candidates produced by us 
under  the  agreement  as  preclinical  development  candidates,  upon  the  expiration  of  the  last-to-expire  research  program.  The 
royalty term means, on a product-by-product and country-by-country basis, the period commencing upon the first commercial 
sale of a product and ending upon the later to occur of: (i) the expiration of the last Mersana patent right that covers or claims 
the exploitation of such product in such country, or (ii) 10 years from the date of first commercial sale of such product in such 
country.  Upon  the  expiration  of  each  royalty  term  for  each  product  on  a  country-by-country  basis,  Merck  KGaA’s  exclusive 
license  will  convert  to  a  perpetual,  non-exclusive,  royalty-free  license  with  respect  to  such  product  in  such  country.  Merck 
KGaA may terminate the 2014 Merck KGaA Agreement  in  its entirety or with  respect  to  any  target antigen  for  convenience 
upon 60 days’ prior written notice. Each party may terminate the 2014 Merck KGaA Agreement in its entirety upon an uncured 
material breach of the agreement by the other party. 

Asana Biosciences Collaboration 

16 

 
 
 
 
 
 
 
 
In  March  2012,  we  entered  into  a  collaboration  agreement  with  Asana  Biosciences,  or  Asana  (by  assignment  from  Endo 
Pharmaceuticals Inc.). Pursuant to the terms of this agreement, we used Asana’s novel antibodies to develop novel ADCs using 
our  Fleximer  technology. Asana  is  responsible  for  product  development,  manufacturing  and  commercialization  of  any ADC 
products. 

Strategic relationships to access antibodies and develop new platforms to progress our proprietary pipeline 

Our focus is to progress our proprietary pipeline of ADCs. For this reason, we have collaborated with biotechnology companies 
that have the capability to generate high quality antibodies or that have existing antibodies that we can license for inclusion in 
our ADCs.  We  have  also  entered  into  license  agreements  with  biotechnology  companies  that  own  certain  patent  rights  and 
related know-how that enable us to develop new ADC platforms. These strategic relationships have facilitated the advancement 
of our proprietary pipeline. 

Recepta license for the NaPi2b antibody 

In  July  2015,  we  entered  into  a  license  agreement  with  Recepta  Biopharma  S.A.,  or  Recepta,  a  Brazilian  biopharmaceutical 
company,  licensing  Recepta’s  NaPi2b  antibody  for  use  in  UpRi  and  our  former  product  candidate  XMT-1592  and  granting 
Recepta the exclusive right to commercialize UpRi and XMT-1592 in Brazil, which was amended in September 2021. We refer 
to this as the Recepta License. Under the Recepta License, Recepta granted us an exclusive license and sub-license with respect 
to certain patents licensed by Recepta from Ludwig Institute for Cancer Research and technology owned by Recepta to develop 
and  exploit  products  containing  Recepta’s  NaPi2b  antibody,  including  UpRi  and  XMT-1592,  worldwide  for  the  diagnosis, 
prophylaxis  and  treatment  of  human  cancer.  We  granted  Recepta  an  exclusive  license  under  our  rights  in  such  patents  and 
technology  and  certain  of  our  ADC-related  patents  and  technology  to  commercialize  any  such  products  developed  by  us, 
including  UpRi  and  XMT-1592,  in  Brazil.  We  are  responsible  for  using  commercially  reasonable  efforts  to  develop  and 
commercialize products under the Recepta License globally, with at least one trial site in our Phase 3 clinical trials, and at our 
own expense in certain major markets. Recepta may conduct development activities in Brazil at its own expense after providing 
us  the  opportunity  to  first  conduct  such  activities  at  Recepta’s  expense.  If  a  product  is  successfully  developed  and 
commercialized by Recepta in Brazil, we will use diligent efforts to enter into an agreement for the supply of such products to 
Recepta for sale in Brazil. 

Under the Recepta License, we paid Recepta an upfront payment of $1 million during the year ended December 31, 2015 and 
are obligated to pay Recepta up to $65.5 million in development, regulatory and commercial milestones and tiered royalties in 
the low-single digit percentages on net sales of products outside of Brazil until the expiration of the royalty term if products are 
successfully  developed  and  commercialized.  We  have  incurred  and  paid  $4.0  million  in  development  milestones.  We  are 
entitled  to  receive  tiered  royalties  in  the  low-  to mid-single  digit  percentages  on  net  sales  of  products  in  Brazil  until  the 
expiration  of  the  royalty  term  if  products  are  successfully  developed  and  commercialized.  The  royalty  term  means,  on  a 
product-by-product  and  country-by-country  basis,  the  period  ending  upon  the  later  of  (i) with  respect  to  products 
commercialized  by  Mersana,  the  expiration  of  the  last-to-expire  Recepta  patent  that  covers  the  product  in  such  country 
(including  the  term  of  any  applicable  supplementary  protection  certificate)  or  with  respect  to  products  commercialized  by 
Recepta,  the  expiration  of  the  last-to-expire  Mersana  patent  that  covers  the  product  in  Brazil  (including  the  term  of  any 
applicable supplementary protection certificate) or (ii) 10 years from the date of first commercial sale of such product in such 
country. Upon the expiration of each royalty term in each country for each applicable product, the exclusive licenses granted to 
each  party  under  the  agreement  will  become  fully-paid  up  and  royalty-free.  The  Recepta  License  will  remain  in  effect  until 
otherwise terminated as set forth below. We may terminate the Recepta License for convenience in its entirety or on a country-
by-country  basis  (except  with  respect  to  Brazil)  or  product-by-product  basis  upon  180 days’  prior  written  notice  for  a 
termination in its entirety or upon 45 days’ prior written notice for a termination in part. Each party may terminate the Recepta 
License in its entirety upon bankruptcy or similar proceedings of the other party, upon a patent challenge by the other party or 
upon an uncured material breach of the agreement by the other party. However, if such breach only relates to one country, the 
Recepta License may only be terminated with respect to such country. 

Synaffix commercial license agreement 

In January 2019, we entered into a commercial license agreement with Synaffix B.V., or Synaffix, which we amended and 
restated in November 2021 to expand our relationship with Synaffix and amended again in February 2022 in connection with 
our collaboration with Janssen. We refer to the amended and restated agreement as the Synaffix License. Under the Synaffix 
License, we have the right to develop, manufacture and commercialize ADCs directed to targets using Synaffix’s proprietary 
site-specific conjugation technology for up to twelve targets. We have licensed five targets in connection with our development 
programs and collaborations, and we have the right to license up to six additional targets. We have paid $6.8 million related to 

17 

 
 
 
 
 
 
 
the Synaffix License, comprised of $4.0 million in reservation and license fees, $1.8 million in milestone payments and $1.0 
million which may be applied to future reservation and license fees, as well as certain portions of potential future development 
milestones. We will be obligated to pay in the range of $48.0 million to $132.0 million for development, regulatory and 
commercial milestones. 

Upon commencement of commercial sales of any ADC product directed to a licensed target, if any, we are required to pay to 
Synaffix  tiered  royalties  in  the  low-single  digit  percentages  on  net  sales  of  the  respective  products.  The  Synaffix  License 
remains  in  effect  on  a  country-by-country  and  licensed  product-by-licensed  product  basis  until  the  expiration  of  the  last-to-
expire valid claim in a patent licensed under the Synaffix License covering such product in such country. Upon the expiration of 
the Synaffix License for each licensed product in each country, the licenses granted to us for such product in such country will 
become fully paid-up and perpetual. We may terminate the Synaffix License in its entirety or on a licensed product-by-licensed 
product basis at any time. Either party may terminate the Synaffix License, subject to a specified notice and cure period, for a 
breach by the other party of a material provision of the agreement or upon an insolvency-related event experienced by the other 
party. 

Manufacturing 

We  do  not  own  or  operate  and  currently  have  no  plans  to  establish  any  current  good  manufacturing  practices,  or  cGMP, 
compliant  manufacturing  facilities.  We  currently  rely,  and  expect  to  continue  to  rely,  on  external  Contract  Manufacturing 
Organizations, or CMOs, for the manufacture of product to support our activities through regulatory approval and commercial 
manufacturing. We have personnel with pharmaceutical development and manufacturing experience who are responsible for the 
relationships with our CMOs. In the future, we expect to use these CMOs to manufacture commercial supply of our products, 
which will require these CMOs to increase scale of production. We do not currently have qualified  alternate  suppliers in  the 
event  the  current  CMOs  that  we  utilize  are  unable  to  scale  production  for  commercial  manufacturing.  The  Dolaflexin, 
Dolasynthen and Immunosynthen manufacturing processes involve readily available starting materials and use unit operations 
that are well-precedented in the field of chemical/pharmaceutical production. The current UpRi supply chain utilizes the same 
vendors  that  we  could  use  for  commercialization.  The  current  supply  chains  for  XMT-1660  and  XMT-2056  have  several 
vendors in common, and based on what we know today, we believe we could use these vendors or would be able to identify and 
contract with other vendors on commercially reasonable terms for commercialization purposes. 

Government regulation 

The  research,  development,  testing,  manufacture,  quality  control,  packaging,  labeling,  storage,  record-keeping,  distribution, 
import,  export,  promotion,  advertising,  marketing,  sale,  pricing  and  reimbursement  of  drug  and  biologic  products  are 
extensively  regulated  by  governmental  authorities  in  the  United  States  and  other  countries.  The  processes  for  obtaining 
regulatory  approvals  in  the  United  States  and  in  foreign  countries  and  jurisdictions,  along  with  compliance  with  applicable 
statutes  and  regulations  and  other  regulatory  requirements,  both  pre-approval  and  post-approval,  require  the  expenditure  of 
substantial time and financial resources. The regulatory requirements applicable  to  biological  product development, approval 
and  marketing  are  subject  to  change,  and  regulations  and  administrative  guidance  often  are  revised  or  reinterpreted  by  the 
agencies in ways that may have a significant impact on our business. 

U.S. government regulation of biological products 

In the United States, the FDA licenses biological products, or biologics, under the Public Health Service Act, or the PHSA, and 
regulates such products under the Food, Drug and Cosmetic Act, or FDCA. A company, institution, or organization which takes 
responsibility for the initiation and management of a clinical development program for such products, and for their regulatory 
approval, is typically referred to as a sponsor. A sponsor seeking approval to market and distribute a new biologic in the United 
States must satisfactorily complete each of the following steps: 

• 

• 

• 

completion  of  preclinical  laboratory  tests,  animal  studies  and  formulation  studies  according  to  good  laboratory 
practices, or GLP, regulations or other applicable regulations; 

design  of  a  clinical  protocol  and  submission  to  the  FDA  of  an  IND,  which  must  become  effective  before  human 
clinical trials may begin and must be updated when certain changes are made; 

approval by an independent institutional review board, or IRB, or ethics committee representing each clinical trial site 
before each clinical trial may be initiated; 

18 

 
• 

• 

• 

• 

• 

performance  of  adequate  and  well-controlled  human  clinical  trials  in  accordance  with  applicable  IND  regulations, 
good clinical practices, or GCPs, and other clinical-trial related regulations to evaluate the safety and efficacy of the 
investigational product for each proposed indication; 

preparation and submission to the FDA of a BLA requesting marketing approval for one or more proposed indications, 
including payment of application user fees; 

review of the BLA by an FDA advisory committee, where applicable; 

satisfactory completion of one or more FDA inspections of the manufacturing facility or facilities at which the biologic 
is  produced  to  assess  compliance  with  cGMP  requirements  to  assure  that  the  facilities,  methods  and  controls  are 
adequate to preserve the product’s identity, strength, quality and purity; 

satisfactory completion of any FDA audits of clinical trial sites to assure compliance with GCPs and the integrity of 
the clinical data submitted in support of the BLA; and 

•  FDA review and approval of the BLA, which may be subject to additional post- approval requirements, including the 
potential  requirement  to  implement  a  Risk  Evaluation  and  Mitigation  Strategy,  or  REMS,  and  any  post-  approval 
clinical trials required by the FDA. 

Preclinical studies 
Before a sponsor begins testing a product candidate with potential therapeutic value in humans, the product candidate enters the 
preclinical testing stage. Preclinical tests include laboratory evaluations of product chemistry, formulation and stability, as well 
as other studies to evaluate, among other things, the toxicity of the product candidate. These studies are often referred to as 
IND-enabling studies. The conduct of the preclinical tests and formulation of the compounds for testing must comply with 
federal regulations and requirements, including GLP regulations and standards and the United States Department of 
Agriculture’s Animal Welfare Act, if applicable. The results of the preclinical tests, together with manufacturing information 
and analytical data, are submitted to the FDA as part of an IND. Some long-term preclinical testing, such as animal tests of 
reproductive adverse events and carcinogenicity, and long-term toxicity studies, may continue after the IND is submitted. 

The IND and IRB processes 

An IND is an exemption from the FDCA that allows an unapproved product candidate to be shipped in interstate commerce for 
use in an investigational clinical trial and a request for FDA authorization to administer such investigational product to humans. 
An IND must be secured prior to interstate shipment and administration of any product candidate that is not the subject of an 
approved BLA. In support of a request for an IND, sponsors must submit a protocol for each clinical trial and any subsequent 
protocol amendments must be submitted to the FDA as part of the IND. An IND automatically becomes effective 30 days after 
receipt by the FDA, unless before that time the FDA raises concerns or questions related to one or more proposed clinical trials 
and  places  the  trial  on  a  clinical  hold.  In  such  a  case,  the  IND  sponsor  and  the  FDA  must  resolve  any  outstanding  concerns 
before the clinical trial may proceed. As a result, submission of an IND may not result in the FDA allowing clinical trials to 
commence. 

Following commencement of a clinical trial under an IND, the FDA may also place a clinical hold or partial clinical hold on 
that trial. A clinical hold is an order issued by the FDA to the sponsor to delay a proposed clinical investigation or to suspend an 
ongoing investigation. A partial clinical hold is a delay or suspension of only part of the clinical work requested under the IND. 
For example, a partial clinical hold might state that a specific protocol or part of a protocol may not proceed, while other parts 
of a protocol or other protocols may do so. No more than 30 days after the imposition of a clinical hold or partial clinical hold, 
the FDA will provide the sponsor a written explanation of the basis for the hold. Following the issuance of a clinical hold or 
partial clinical hold, a clinical investigation may only resume once the FDA has notified the sponsor that the investigation may 
proceed. The FDA will base that determination on information provided by the sponsor correcting the deficiencies previously 
cited  or  otherwise  satisfying  the  FDA  that  the  investigation  can  proceed  or  recommence.  Occasionally,  clinical  holds  are 
imposed due to manufacturing issues that may present safety issues for the clinical trial subjects.  

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A  sponsor  may  choose,  but  is  not  required,  to  conduct  a  foreign  clinical  trial  under  an  IND.  When  a  foreign  clinical  trial  is 
conducted  under  an  IND,  all  IND  requirements  must  be  met  unless  waived  by  the  FDA. When  a  foreign  clinical  trial  is  not 
conducted under an IND, the sponsor must ensure that  the  trial complies  with certain regulatory requirements  of  the FDA in 
order to use the trial data as support for an IND or application for marketing approval. Specifically, the trials must be conducted 
in accordance with GCP, including undergoing review and receiving approval by an independent ethics committee, or IEC, and 
seeking and receiving informed consent from subjects. GCP requirements encompass both ethical and data integrity standards 
for  clinical  trials.  The  FDA’s  regulations  are  intended  to  help  ensure  the  protection  of  human  subjects  enrolled  in  non-IND 
foreign clinical trials, as well as the quality and integrity of the resulting data.  

In  addition  to  the  foregoing  IND  requirements,  an  IRB  representing  each  institution  participating  in  the  clinical  trial  must 
review and approve the plan for any clinical trial before it commences at that institution, and the IRB must conduct continuing 
review  and  re-approve  the  trial  at  least  annually.  The  IRB,  which  must  operate  in  compliance  with  FDA  regulations,  must 
review  and  approve,  among other  things,  the  clinical  trial  protocol  and  informed  consent  information  to  be  provided  to  trial 
subjects  and  must  monitor  the  trial  until  completed.  An  IRB  can  suspend  or  terminate  approval  of  a  clinical  trial  at  its 
institution, or an institution it represents, if the clinical trial is not being conducted in accordance with the IRB’s requirements 
or if the product candidate has been associated with unexpected serious harm to patients.  

Additionally, some trials are overseen by an independent group of qualified experts organized by the trial sponsor, known as a 
data safety monitoring board, or DSMB. This group provides authorization as to whether or not a trial may move forward at 
designated checkpoints based on review of available data from the trial, to which only the DSMB maintains access. Suspension 
or  termination of development during any phase of a  clinical trial  can  occur  if the  DSMB  determines that the participants  or 
patients are being exposed to an unacceptable health risk.  

Expanded access 

Expanded access, sometimes called “compassionate use,” is the use of investigational new products outside of clinical trials to 
treat patients with serious or immediately life-threatening diseases or conditions when there are no comparable or satisfactory 
alternative  treatment  options.  The  rules  and  regulations  related  to  expanded  access  are  intended  to  improve  access  to 
investigational  products  for  patients  who  may  benefit  from  investigational  therapies.  FDA  regulations  allow  access  to 
investigational products under an IND by the company or the treating physician for treatment purposes on a case-by-case basis 
for:  individual  patients  (single-patient  IND  applications  for  treatment  in  emergency  settings  and  non-emergency  settings); 
intermediate-size patient populations; and larger populations for use of the investigational product under a treatment protocol or 
Treatment IND Application. 

When considering an IND application for expanded access to an investigational product with the purpose of treating a patient or 
a  group  of  patients,  the  sponsor  and  treating  physicians  or  investigators  will  determine  suitability  when  all  of  the  following 
criteria  apply:  patient(s)  have  a  serious  or  immediately  life-threatening  disease  or  condition,  and  there  is  no  comparable  or 
satisfactory alternative therapy to diagnose, monitor, or treat the disease or condition; the potential patient benefit justifies the 
potential risks of the  treatment and the  potential risks  are  not  unreasonable in the  context or condition  to be treated; and the 
expanded  use  of  the  investigational  product  for  the  requested  treatment  will  not  interfere  with  the  initiation,  conduct  or 
completion  of  clinical  investigations  that  could  support  marketing  approval  of  the  product  or  otherwise  compromise  the 
potential development of the product.  

There is no obligation for a sponsor to make its investigational products available for expanded access; however, as required by 
amendments to the FDCA included in the 21st Century Cures Act, or the Cures Act, passed in 2016, if a sponsor has a policy 
regarding  how  it  responds  to  expanded  access  requests  with  respect  to  product  candidates  in  development  to  treat  serious 
diseases  or  conditions,  it  must  make  that  policy  publicly  available.  Sponsors  are  required  to  make  such  policies  publicly 
available upon the earlier of initiation of a Phase 2 or Phase 3 trial for a covered investigational product; or 15 days after the 
investigational  product  receives  designation  from  the  FDA  as  a  breakthrough  therapy,  fast  track  product,  or  regenerative 
medicine advanced therapy.  

In  addition,  on  May  30,  2018,  the  Right  to  Try Act  was  signed  into  law.  The  law,  among  other  things,  provides  a  federal 
framework for certain patients to access certain investigational new products that have completed a Phase 1 clinical trial and 
that are undergoing investigation for FDA approval. Under certain circumstances, eligible patients can seek treatment without 
enrolling  in  clinical  trials  and  without  obtaining  FDA  permission  under  the  FDA  expanded  access  program.  There  is  no 
obligation  for  a  manufacturer  to  make  its  products  available  to  eligible  patients  as  a  result  of  the  Right  to  Try Act,  but  the 
manufacturer must develop an internal policy and respond to patient requests according to that policy.  

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Human clinical trials 

Clinical trials involve the administration of the investigational product candidate to human subjects under the supervision of a 
qualified  investigator  in  accordance  with  GCP  requirements  which  include,  among  other  things,  the  requirement  that  all 
research  subjects  provide  their  informed  consent  in  writing  before  they  participate  in  any  clinical  trial.  Clinical  trials  are 
conducted under written clinical trial protocols detailing, among other things, the objectives of the trial, inclusion and exclusion 
criteria, the parameters to be used in monitoring safety  and the  effectiveness  criteria to be  evaluated.  Each protocol, and  any 
subsequent  material  amendment  to  the  protocol,  must  be  submitted  to  the  FDA  as  part  of  the  IND,  and  progress  reports 
detailing the status of the clinical trials must be submitted to the FDA annually. The FDA has issued regulations authorizing a 
sponsor to transfer certain responsibilities for the conduct of a clinical trial to a contract research organization, or CRO. 

Human clinical trials are typically conducted in three sequential phases, but the phases may overlap or be combined. Additional 
trials may also be required after approval.  

Phase  1  clinical  trials  are  initially  conducted  in  a  limited  population,  which  may  be  healthy  volunteers  or  subjects  with  the 
target  disease,  to  test  the  product  candidate  for  safety,  including  adverse  effects,  dose  tolerance,  absorption,  metabolism, 
distribution,  excretion  and  pharmacodynamics  in  healthy  humans  or  in  patients.  During  Phase  1  clinical  trials,  information 
about  the  product  candidate’s  pharmacokinetics  and  pharmacological  effects  may  be  obtained  to  permit  the  design  of  well-
controlled and scientifically valid Phase 2 clinical trials.  

Phase  2  clinical  trials  are  generally  conducted  in  a  limited  patient  population  to  identify  possible  adverse  effects  and  safety 
risks, evaluate the efficacy of the product candidate for specific targeted indications and determine dose tolerance and optimal 
dosage. Multiple Phase 2  clinical trials  may be conducted by  the  sponsor  to obtain  information  prior  to  beginning  larger and 
more costly Phase 3 clinical trials. Phase 2 clinical trials are typically well-controlled and closely monitored.  

Phase 3 clinical trials proceed if the Phase 2 clinical trials demonstrate that a dose range of the product candidate is potentially 
effective and has an acceptable safety profile. Phase 3 clinical trials are undertaken using a larger patient population to further 
evaluate dosage, provide substantial evidence of clinical efficacy and further test for safety in an expanded and diverse patient 
population at multiple geographically dispersed  clinical trial  sites. A well-controlled,  statistically  robust  Phase  3  clinical  trial 
may be designed to deliver the data that regulatory authorities will use to decide whether or not to approve, and, if approved, 
how to appropriately label a new biologic product. Such Phase 3 clinical trials are referred to as “pivotal” trials.  

A clinical trial may combine the elements of more than one phase and the FDA often requires more than one Phase 3 trial to 
support marketing approval of a product candidate. A company’s designation of a clinical trial as being of a particular phase is 
not  necessarily  indicative  that  the  trial  will  be  sufficient  to  satisfy  the  FDA  requirements  of  that  phase  because  this 
determination cannot be made until the protocol and data have been submitted to and reviewed by the FDA. Moreover, as noted 
above, a pivotal trial is a clinical trial that is believed to satisfy FDA requirements for the evaluation of a product candidate’s 
safety and efficacy such that it can be used, alone or  with  other  pivotal or  non-pivotal trials,  to support  regulatory approval. 
Generally, pivotal trials are Phase 3 trials, but they may be Phase 2 trials if the design provides a well-controlled and reliable 
assessment of clinical benefit, particularly in an area of unmet medical need. 

In some cases, the FDA may approve a BLA for a product candidate but require the sponsor to conduct additional clinical trials 
to further assess the product candidate’s safety and effectiveness after approval. Such post-approval trials, typically referred to 
as Phase 4 clinical trials, may be conducted after initial marketing approval. These trials are used to gain additional experience 
from the treatment of a larger number of patients in the intended treatment group. In certain instances, the FDA may mandate 
the performance of Phase 4 clinical trials, such as to verify clinical benefit in the case of products approved under accelerated 
approval regulations. Failure to exhibit due diligence with regard to conducting mandatory Phase 4 clinical trials could result in 
withdrawal of FDA approval for products. In December 2022, with the passage of the Food and Drug Omnibus Reform Act, or 
FDORA, Congress required sponsors to develop and submit a diversity action plan for each phase 3 clinical trial or any other 
“pivotal study” of a new drug or biological product. These plans are meant to encourage the enrollment of more diverse patient 
populations in late-stage clinical trials of FDA-regulated products. Specifically, action plans must include the sponsor’s goals 
for  enrollment,  the  underlying  rationale  for  those  goals,  and  an  explanation  of  how  the  sponsor  intends  to  meet  them.  In 
addition to these requirements, the legislation directs the FDA to issue new guidance on diversity action plans. 

In  March  2022,  the  FDA  released  final  guidance  entitled  “Expansion  Cohorts:  Use  in  First-In-Human  Clinical  Trials  to 
Expedite Development of Oncology Drugs and Biologics,” which outlines how developers can utilize an adaptive trial design 
commonly referred to as a seamless trial design in early stages of oncology biological product development (i.e., the first-in-
human clinical trial) to compress the traditional three phases of trials into one continuous trial called an expansion cohort trial. 
Information  to  support  the  design  of  individual  expansion  cohorts  are  included  in  IND  applications  and  assessed  by  FDA. 

21 

 
Expansion  cohort  trials  can  potentially  bring  efficiency  to  product  development  and  reduce  developmental  costs  and 
time.Finally, sponsors of clinical trials are required to register and disclose certain clinical trial information on a public registry 
(clinicaltrials.gov)  maintained  by  the  U.S.  National  Institutes  of  Health,  or  NIH.  In  particular,  information  related  to  the 
product, patient population, phase of investigation, clinical trial sites and investigators and other aspects of the clinical trial is 
made public as part of the registration of the clinical trial. The NIH’s Final Rule on registration and reporting requirements for 
clinical trials became effective in 2017. Although the FDA has historically not enforced these reporting requirements due to the 
long delay  of  the  U.S.  Department  of  Health  and  Human  Services,  or  HHS,  in  issuing  final  implementing  regulations,  those 
regulations have now been issued and the FDA has issued several Notices of Noncompliance to manufacturers since April 2021.  

Interactions with FDA during the clinical development program 

Following the clearance of an IND and the commencement of clinical trials, the sponsor will continue to have interactions with 
the FDA. Progress reports detailing the results of clinical trials must be submitted annually within 60 days of the anniversary 
dates  that  the  IND  went  into  effect  and  more  frequently  if  serious  adverse  events  occur.  These  reports  must  include  a 
development  safety  update  report,  or  DSUR.  In  addition,  IND  safety  reports  must  be  submitted  to  the  FDA  for  any  of  the 
following:  serious  and  unexpected  suspected  adverse  reactions;  findings  from  other  trials  or  animal  or  in  vitro  testing  that 
suggest a significant risk in humans exposed to the product; and any clinically important increase in the occurrence of a serious 
suspected adverse reaction over that listed in the protocol or investigator brochure. Phase 1, Phase 2 and Phase 3 clinical trials 
may not be completed successfully within any specified period, or at all. The FDA will typically inspect one or more clinical 
sites to assure compliance with GCP and the integrity of the clinical data submitted. 

In  addition,  sponsors  are  given  opportunities  to  meet  with  the  FDA  at  certain  points  in  the  clinical  development  program. 
Specifically,  sponsors  may  meet  with  the  FDA  prior  to  the  submission  of  an  IND  (Pre-IND  meeting),  at  the  end  of  Phase  2 
clinical  trial  (EOP2  meeting)  and  before  a  BLA  is  submitted  (Pre-BLA  meeting).  Meetings  at  other  times  may  also  be 
requested.  There  are  four  types  of  meetings  that  occur  between  sponsors  and  the  FDA.  Type A  meetings  are  those  that  are 
necessary  for  an  otherwise  stalled  product  development  program  to  proceed  or  to  address  an  important  safety  issue. Type  B 
meetings include pre-IND and pre-BLA meetings, as well as end of phase meetings such as EOP2 meetings. A Type C meeting 
is  any  meeting  other  than  a  Type  A  or  Type  B  meeting  regarding  the  development  and  review  of  a  product,  including  for 
example meetings to facilitate early consultations on the use of a biomarker as a new surrogate endpoint that has never been 
previously used as the primary basis for product approval in the proposed context of use. Finally, a Type D meeting is focused 
on a narrow set of issues, which should be limited to no more than two focused topics, and should not require input from more 
than three disciplines or divisions.  

Manufacturing and other regulatory requirements 

Concurrent with clinical trials, sponsors usually complete additional animal safety studies, develop additional information about 
the  chemistry  and  physical  characteristics  of  the  product  candidate  and  finalize  a  process  for  manufacturing  commercial 
quantities  of  the  product  candidate  in  accordance  with  cGMP  requirements.  The  manufacturing  process  must  be  capable  of 
consistently producing quality batches of the product candidate and, among other criteria, the sponsor must develop methods 
for  testing  the  identity,  strength,  quality,  and  purity  of  the  finished  product.  Additionally,  appropriate  packaging  must  be 
selected  and  tested,  and  stability  studies  must  be  conducted  to  demonstrate  that  the  product  candidate  does  not  undergo 
unacceptable deterioration over its shelf life. 

Specifically, the FDA’s regulations require that pharmaceutical products be manufactured in specific approved facilities and in 
accordance  with  cGMPs.  The  cGMP  regulations  include  requirements  relating  to  organization  of  personnel,  buildings  and 
facilities, equipment, control of components and product containers and closures, production and process controls, packaging 
and  labeling  controls,  holding  and  distribution,  laboratory  controls,  records  and  reports  and  returned  or  salvaged  products. 
Manufacturers  and  other  entities  involved  in  the  manufacture  and  distribution  of  approved  pharmaceuticals  are  required  to 
register their establishments with the FDA and some state agencies, and they are subject to periodic unannounced inspections 
by  the  FDA  for  compliance  with  cGMPs  and  other  requirements.  The  PREVENT  Pandemics  Act,  which  was  enacted  in 
December  2022,  clarifies  that  foreign  drug  manufacturing  establishments  are  subject  to  registration  and  listing  requirements 
even if a drug or biologic undergoes further manufacture, preparation, propagation, compounding, or processing at a separate 
establishment outside the United States prior to being imported or offered for import into the United States.  

Inspections  must  follow  a  “risk-based  schedule”  that  may  result  in  certain  establishments  being  inspected  more  frequently. 
Manufacturers may also have to provide, on request, electronic  or physical records  regarding  their  establishments. Delaying, 
denying,  limiting,  or  refusing  inspection  by  the  FDA  may  lead  to  a  product being  deemed  to  be  adulterated.  Changes  to  the 
manufacturing  process,  specifications  or  container  closure  system  for  an  approved  product  are  strictly  regulated  and  often 
require  prior  FDA  approval  before  being  implemented.  The  FDA’s  regulations  also  require,  among  other  things,  the 

22 

 
investigation  and  correction  of  any  deviations  from  cGMP  and  the  imposition  of  reporting  and  documentation  requirements 
upon the sponsor and any third-party manufacturers involved in producing the approved product.  

Pediatric trials 

Under the Pediatric Research Equity Act, or PREA, applications and certain types of supplements to applications must contain 
data that are adequate to assess the safety and effectiveness of the product for the claimed indications in all relevant pediatric 
subpopulations,  and  to  support  dosing  and  administration  for  each  pediatric  subpopulation  for  which  the  product  is  safe  and 
effective. The sponsor must submit an initial Pediatric Study Plan, or PSP, within 60 days of an end-of-phase 2 meeting or as 
may be agreed between the sponsor and the FDA. Those plans must contain an outline of the proposed pediatric clinical trial or 
trials  that  the  sponsor  plans  to  conduct,  including  trial  objectives  and  design,  age  groups,  relevant  endpoints  and  statistical 
approach, or a justification for not including such detailed information, and any request for a deferral of pediatric assessments 
or  a  full  or  partial  waiver  of  the  requirement  to  provide  data  from  pediatric  trials  along  with  supporting  information.  The 
sponsor and the FDA must reach agreement on a final plan. A sponsor can submit amendments to an agreed-upon initial PSP at 
any time if changes to the pediatric plan  need  to be  considered  based on  data  collected from nonclinical  studies,  early phase 
clinical trials, and/or other clinical development programs.  

For investigational products intended to treat a serious or life-threatening disease or condition, the FDA must, upon the request 
of a sponsor, meet to discuss preparation of the initial PSP or to discuss deferral or waiver of pediatric assessments. In addition, 
the  FDA will meet early in the development  process  to  discuss  pediatric  study  plans  with  sponsors, and  the  FDA must  meet 
with sponsors by no later than the end-of-phase 1 meeting for serious or life-threatening diseases and by no later than ninety 
days after the FDA’s receipt of the PSP. 

The FDA may, on its own initiative or at the request of the sponsor, grant deferrals for submission of some or all pediatric data 
until after approval of the product for use in adults, or full or partial waivers from the pediatric data requirements. A deferral 
may be granted for several reasons, including a finding that the product or therapeutic candidate is ready for approval for use in 
adults  before  pediatric  trials  are  complete  or  that  additional  safety  or  effectiveness  data  needs  to  be  collected  before  the 
pediatric trials begin. The law now requires the FDA to  send  a PREA  Non-Compliance letter  to  sponsors who  have failed  to 
submit their pediatric assessments required under PREA, have failed to seek or obtain a deferral or deferral extension or have 
failed  to  request  approval  for  a  required  pediatric  formulation.  Unless  otherwise  required  by  regulation,  the  pediatric  data 
requirements do not apply to products with orphan designation, although FDA has recently taken steps to limit what it considers 
abuse of this statutory exemption in PREA. The FDA also maintains a list of diseases that are exempt from PREA requirements 
due to low prevalence of disease in the pediatric population. 

Expedited review programs  

The FDA is authorized to expedite the review of applications in several ways. Under the Fast Track program, the sponsor of a 
product candidate may request the FDA to designate the product for a  specific  indication as a Fast Track product  concurrent 
with  or  after  the  filing  of  the  IND.  Candidate  products  are  eligible  for  Fast  Track  designation  if  they  are  intended  to  treat  a 
serious or life-threatening condition and demonstrate the potential to address unmet medical needs for the condition. Fast Track 
designation  applies  to  the  combination  of  the  product  candidate  and  the  specific  indication  for  which  it  is  being  studied.  In 
addition to other benefits, such as the ability to have greater interactions with the FDA, the FDA may initiate review of sections 
of a Fast Track application before the application is complete, a process known as rolling review.  

Any product candidate submitted to the FDA for marketing, including under a Fast Track program, may be eligible for other 
types  of  FDA  programs  intended  to  expedite  development  and  review,  such  as  breakthrough  therapy  designation,  priority 
review and accelerated approval.  

•  Breakthrough  therapy  designation.  To  qualify  for  the  breakthrough  therapy  program,  product  candidates  must  be 
intended to treat a serious or life-threatening disease or condition and preliminary clinical evidence must indicate that 
such  product  candidates  may  demonstrate  substantial  improvement  on  one  or  more  clinically  significant  endpoints 
over existing therapies. The FDA will seek to ensure the sponsor of a breakthrough therapy product candidate receives 
intensive guidance on an efficient development  program,  intensive  involvement  of senior managers  and experienced 
staff on a proactive, collaborative and cross-disciplinary review and rolling review.  

•  Priority review. A product candidate is eligible for priority review if  it treats a serious  condition  and,  if approved,  it 
would be a significant improvement in the safety or effectiveness of the treatment, diagnosis or prevention compared 
to marketed products. FDA aims to complete its review of priority review applications within six months as opposed to 
10 months for standard review.  

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•  Accelerated approval. Biologic products studied for their safety and effectiveness in treating serious or life-threatening 
illnesses  and  that provide  meaningful  therapeutic benefit  over  existing  treatments may  receive  accelerated  approval. 
Accelerated approval means that a product  candidate  may be  approved  on  the basis  of  adequate  and  well controlled 
clinical trials establishing that the product candidate has an effect on a surrogate endpoint that is reasonably likely to 
predict a clinical benefit, or on the basis of an effect on a clinical endpoint other than survival or irreversible morbidity 
or mortality or other clinical benefit, taking  into  account  the  severity,  rarity  and  prevalence  of the condition and the 
availability  or  lack  of  alternative  treatments. As  a  condition  of  approval,  the  FDA  may  require  that  a  sponsor  of  a 
biologic  product  candidate  receiving  accelerated  approval  perform  adequate  and  well  controlled  post-marketing 
clinical  trials.  In  addition,  the  FDA  currently  requires  as  a  condition  for  accelerated  approval  pre-approval  of 
promotional materials.  

With passage of FDORA in December 2022, Congress modified certain provisions governing accelerated approval of 
drug  and  biologic  products.  Specifically,  the  new  legislation  authorized  the  FDA  to:  require  a  sponsor  to  have  its 
confirmatory  clinical  trial  underway  before  accelerated  approval  is  awarded;  require  a sponsor  of  a product  granted 
accelerated  approval  to  submit  progress  reports  on  its  post-approval  studies  to  the  FDA  every  six  months,  until  the 
study is completed; and use expedited procedures to withdraw accelerated approval of a new drug application or BLA 
after the confirmatory trial fails to verify the product’s clinical benefit. Further, FDORA requires the agency to publish 
on its website “the rationale for why a post-approval study is not appropriate or necessary” whenever it decides not to 
require such a study upon granting accelerated approval.  

•  Regenerative  advanced  therapy. With  passage  of  the  21st  Century  Cures Act,  or  the  Cures Act,  in  December  2016, 
Congress  authorized  the  FDA  to  accelerate  review  and  approval  of  products  designated  as  regenerative  advanced 
therapies. A  product  is  eligible  for  this  designation  if  it  is  a  regenerative  medicine  therapy  that  is  intended  to  treat, 
modify, reverse or cure a serious or life-threatening disease  or  condition and  preliminary  clinical  evidence indicates 
that the product candidate has the potential to address unmet medical needs for such disease or condition. The benefits 
of a regenerative advanced therapy designation include early interactions with the FDA to expedite development and 
review, benefits available to breakthrough therapies, potential eligibility for priority review and accelerated approval 
based on surrogate or intermediate endpoints.  

None of these expedited programs changes the standards for approval but each may help expedite the development or approval 
process governing product candidates. 

Submission and filing of BLAs 

Assuming successful completion of the required clinical testing, the results of the preclinical studies and clinical trials, along 
with  information  relating  to  the  product’s  chemistry,  manufacturing,  controls,  safety  updates,  patent  information,  abuse 
information and proposed labeling, are submitted to the FDA as part of an application requesting approval to market the product 
candidate  for  one  or  more  indications.  To  support  marketing  approval,  the  data  submitted  must  be  sufficient  in  quality  and 
quantity to establish the safety, potency and purity of the biological product to the satisfaction of the FDA. The fee required for 
the submission and review of an application under the Prescription Drug User Fee Act, or PDUFA, is substantial (for example, 
for FY2023 this application fee is approximately $3.25 million), and the sponsor of an approved application is also subject to an 
annual program fee, currently more than $394,000 per eligible prescription product. These fees are typically adjusted annually, 
and exemptions and waivers may be available under certain circumstances, including where the applicant is a small business 
submitting its first human therapeutic application for review. 

The FDA conducts a preliminary review of all applications within 60 days of receipt and must inform the sponsor at that time or 
before whether an application is sufficiently  complete to  permit  substantive review. In pertinent  part,  FDA’s regulations state 
that an application “shall not be considered as filed until all pertinent information and data have been received” by the FDA. In 
the  event  that  FDA  determines  that  an  application  does  not  satisfy  this  standard,  it  will  issue  a  Refuse  to  File,  or  RTF, 
determination  to  the  applicant. Typically,  an  RTF  will  be  based  on  administrative  incompleteness,  such  as  clear  omission  of 
information  or  sections  of  required  information  such  that  substantive  and  meaningful  review  is  precluded.  The  FDA  may 
request  additional  information  rather  than  accept  an  application  for  filing.  In  this  event,  the  application  must  be  resubmitted 
with the additional information. The resubmitted application is also subject to review before the FDA accepts it for filing. 

After the submission is accepted for filing, the FDA begins an in-depth substantive review of the application. The FDA reviews 
the  application  to  determine,  among  other  things,  whether  the  proposed  product  is  safe  and  effective  for  its  intended  use, 
whether it has an acceptable purity profile and whether the product is being manufactured in accordance with cGMP. Under the 
goals and policies agreed to by the FDA under PDUFA, the FDA has ten months from the filing date in which to complete its 
initial review of a standard application that is a new molecular entity, and six months from the filing date for an application with 

24 

 
“priority review.” The review process may be extended by the FDA for three additional months to consider new information or 
in the case of a clarification provided by the applicant to address an outstanding deficiency identified by the FDA following the 
original submission. Despite these review goals, it is not uncommon  for  FDA  review  of  an  application to  extend beyond  the 
PDUFA goal date. 

In  connection  with  its  review  of  an  application,  the  FDA  will  typically  submit  information  requests  to  the  applicant  and  set 
deadlines for responses thereto. The FDA will also conduct a pre-approval inspection of the manufacturing facilities for the new 
product to determine whether the manufacturing processes and facilities comply with cGMPs. The FDA will not approve the 
product unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and are 
adequate to assure consistent production of the product within required specifications.  

The  FDA  also  may  inspect  the  sponsor  and  one  or  more  clinical  trial  sites  to  assure  compliance  with  IND  and  GCP 
requirements and the integrity of the clinical data submitted to the FDA. With passage of FDORA, Congress clarified the FDA’s 
authority  to  conduct  inspections  by  expressly  permitting  inspections  of  facilities  involved  in  the  preparation,  conduct,  or 
analysis of clinical and non-clinical studies submitted to the FDA as well as other persons holding study records or involved in 
the study process. 

Additionally,  the  FDA  may  refer  an  application,  including  applications  for  novel  product  candidates  which  present  difficult 
questions  of  safety  or  efficacy,  to  an  advisory  committee  for  review,  evaluation  and  recommendation  as  to  whether  the 
application should be approved and under what conditions. Typically, an advisory committee is a panel of independent experts, 
including  clinicians  and  other  scientific  experts  that  reviews,  evaluates  and  provides  a  recommendation  as  to  whether  the 
application  should  be  approved  and  under  what  conditions.  The  FDA  is  not  bound  by  the  recommendation  of  an  advisory 
committee, but it considers such recommendations when making final decisions on approval.  

The FDA also may require submission of a REMS if it determines that a REMS is necessary to ensure that the benefits of the 
product  outweigh  its  risks  and  to  assure  the  safe  use  of  the  product. The  REMS  could  include  medication  guides,  physician 
communication  plans,  assessment  plans  and/or  elements  to  assure  safe  use,  such  as  restricted  distribution  methods,  patient 
registries  or  other risk  minimization  tools. The  FDA  determines  the  requirement  for a REMS,  as  well  as  the  specific  REMS 
provisions,  on  a  case-by-case  basis.  If  the  FDA  concludes  a  REMS  is  needed,  the  sponsor  of  the  application  must  submit  a 
proposed REMS and the FDA will not approve the application without a REMS. 

Decisions on BLAs 

After  evaluating  the  application  and  all  related  information,  including  the  advisory  committee  recommendations,  if  any,  and 
inspection reports of manufacturing facilities and clinical trial sites, the FDA will issue either a Complete Response Letter, or 
CRL,  or  an  approval  letter. To  reach  this  determination,  the  FDA  must  determine  that  the  expected  benefits  of  the  proposed 
product outweigh its potential risks to patients. This assessment is informed by the severity of the underlying condition and how 
well patients’ medical needs are addressed by currently available therapies; uncertainty about how the premarket clinical trial 
evidence will extrapolate to real-world use of the product in  the  post-market  setting;  and whether  risk management tools are 
necessary to manage specific risks. 

A CRL indicates  that the review cycle  of  the application  is complete,  and  the  application  will  not  be  approved in its present 
form. A CRL generally outlines the deficiencies in the submission and may require substantial additional testing or information 
in  order for  the  FDA  to  reconsider  the  application. The  CRL  may require  additional  clinical  or  other  data,  additional  pivotal 
Phase 3 clinical trial(s) and/or other significant and time- consuming requirements related to clinical trials, preclinical studies or 
manufacturing. If  a  CRL  is  issued,  the  applicant  will  have one  year  to  respond  to  the  deficiencies  identified  by  the  FDA,  at 
which  time  the  FDA  can  deem  the  application  withdrawn  or,  in  its  discretion,  grant  the  applicant  an  additional  six  month 
extension to respond. The FDA has committed to reviewing resubmissions in response to an issued CRL in either two or six 
months depending on the type of information included. Even with the submission of this additional information, however, the 
FDA ultimately may decide that the application does not satisfy the regulatory criteria for approval. 

An approval letter, on the other hand, authorizes commercial marketing of the product with specific prescribing information for 
specific indications. That is, the approval will be limited to the conditions of use (e.g., patient population, indication) described 
in  the  FDA-approved  labeling.  Further,  depending  on  the  specific  risk(s)  to  be  addressed,  the  FDA  may  require  that 
contraindications, warnings or precautions be included in the product labeling, require that post-approval trials, including Phase 
4 clinical trials, be conducted to further assess a product’s safety after approval, require testing  and  surveillance programs to 
monitor the product after commercialization or impose other conditions, including distribution and use restrictions or other risk 
management mechanisms under a REMS which can materially affect the potential market and profitability of the product. The 
FDA may prevent or limit further marketing of a product based on the results of post-marketing trials or surveillance programs. 

25 

 
After approval, some types of changes  to the approved product, such  as adding new  indications,  manufacturing changes  and 
additional labeling claims, are subject to further testing requirements and FDA review and approval. 

Post-approval requirements 

Following  approval  of  a  new  prescription  product,  the  manufacturer,  the  approved  product  and  the  product’s  manufacturing 
locations  are  subject  to  pervasive  and  continuing  regulation  by  the  FDA,  governing,  among  other  things,  monitoring  and 
record-keeping  activities,  reporting  of  adverse  experiences  with  the  product  and  product  problems  to  the  FDA,  product 
sampling and distribution, manufacturing and promotion and advertising. Although physicians may prescribe legally available 
products  for  unapproved  uses  or  patient  populations  (i.e.,  “off-label  uses”),  manufacturers  may  not  market  or  promote  such 
uses. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses, and a 
company that is found to have improperly promoted off-label uses may be subject to significant liability. In September 2021, 
the  FDA  published  final  regulations  which  describe  the  types  of  evidence  that  the  agency  will  consider  in  determining  the 
intended use of a biologic. 

It  may  be  permissible,  under  very  specific,  narrow  conditions,  for  a  manufacturer  to  engage  in  non-promotional,  non-
misleading  communication  regarding  off-label  information,  such  as  distributing  scientific  or  medical  journal  information. 
Moreover, with passage of the Pre-Approval Information Exchange Act in December 2022, sponsors of products that have not 
been  approved  may  proactively  communicate  to  payors  certain  information  about  products  in  development  to  help  expedite 
patient  access  upon  product  approval.  Previously,  such  communications  were  permitted  under  FDA  guidance  but  the  new 
legislation explicitly provides protection to sponsors who convey certain information about products in development to payors, 
including unapproved uses of approved products. 

If a company is found to have promoted off-label uses, it may become subject to administrative and judicial enforcement by the 
FDA, the Department of Justice, or the Office of the Inspector General of the Department of Health and Human Services, as 
well as state authorities. This could subject a company to a range of penalties that could have a significant commercial impact, 
including  civil  and  criminal  fines  and  agreements  that  materially  restrict  the  manner  in  which  a  company  promotes  or 
distributes products, as well as adverse  public relations  and reputational  harm. The  federal  government  has  levied large civil 
and criminal fines against companies for alleged improper promotion, and has also requested that companies enter into consent 
decrees or permanent injunctions under which specified promotional conduct is changed or curtailed. 

Further, if there are any modifications to the product, including changes in indications, labeling or manufacturing processes or 
facilities,  the  sponsor  may  be  required  to  submit  and  obtain  FDA  approval  of  a  new  application  or  supplement,  which  may 
require  the  sponsor  to  develop  additional  data  or  conduct  additional  preclinical  studies  and  clinical  trials.  Securing  FDA 
approval for new indications is similar to the process for approval of the original indication and requires, among other things, 
submitting  data  from  adequate  and  well-controlled  clinical  trials  to  demonstrate  the  product’s  safety  and  efficacy  in  the  new 
indication. Even if such trials are conducted, the FDA may not approve any expansion of the labeled indications for use in a 
timely  fashion,  or  at  all.  There  also  are  continuing,  annual  user  fee  requirements  that  are  now  assessed  as  program  fees  for 
certain products. 

In addition, the FDA may withdraw the approval if compliance with regulatory requirements and standards is not maintained or 
if  problems  occur  after  the  product  reaches  the  market.  Later  discovery  of  previously  unknown  problems  with  a  product, 
including  adverse  events  of  unanticipated  severity  or  frequency,  or  with  manufacturing  processes,  or  failure  to  comply  with 
regulatory requirements, may result in mandatory revisions to the approved labeling to add new safety information, imposition 
of  post-market clinical  trials requirement  to  assess new  safety risks or  imposition of  distribution or other  restrictions under a 
REMS program.  

Other potential consequences include, among other things: 

• 

• 

restrictions on the marketing or manufacturing of the product, complete withdrawal of the product from the market or 
product recalls; 

safety  alerts,  Dear  Healthcare  Provider  letters,  press  releases  or  other  communications  containing  warnings or  other 
safety information about a product; 

•  mandated modification of promotional materials and labeling and issuance of corrective information; 

• 

fines,  warning  letters,  untitled  letters  or  other  enforcement-related  letters  or  clinical  holds  on  post-approval  clinical 
trials; 

26 

 
• 

• 

• 

• 

refusal  of  the  FDA  to  approve  pending  applications  or  supplements  to  approved  applications,  or  suspension  or 
revocation of product approvals; 

product seizure or detention, or refusal to permit the import or export of products; 

injunctions or the imposition of civil or criminal penalties; and 

consent decrees, corporate integrity agreements, debarment, or exclusion from federal health care programs. 

Regulatory exclusivity governing biologics 

When a biological product is licensed for marketing by FDA with approval of a BLA, the product may be entitled to certain 
types  of  market  and data  exclusivity  barring  FDA  from  approving  competing products  for  certain  periods  of  time.  In  March 
2010,  the  Patient  Protection  and  Affordable  Care  Act  was  enacted  in  the  United  States  and  included  the  Biologics  Price 
Competition  and  Innovation Act  of  2009,  or  the  BPCIA.  The  BPCIA  amended  the  PHSA  to  create  an  abbreviated  approval 
pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. To 
date, the FDA has approved a number of biosimilars and the first interchangeable biosimilar product was approved on July 30, 
2021 and a second product previously approved as a biosimilar was designated as interchangeable in October 2021. 

Under  the  BPCIA,  a  manufacturer  may  submit  an  application  for  a  product  that  is  “biosimilar  to”  a  previously  approved 
biological product, which the statute refers to as a “reference product.” In order for the FDA to approve a biosimilar product, it 
must find that there are no clinically meaningful differences between the reference product and the proposed biosimilar product 
in terms of safety, purity and potency. The  biosimilar  sponsor may demonstrate that its product  is biosimilar to  the  reference 
product on the basis of data from analytical studies, animal studies and one or more clinical trials to demonstrate safety, purity 
and potency in one or more appropriate conditions of use for which the reference product is approved.  
For the FDA to approve a biosimilar product as interchangeable with a reference product, the agency must find not only that the 
product is biosimilar to the reference product but also that it can be expected to produce the same clinical results as the 
reference product such that the two products may be switched without increasing safety risks or risks of diminished efficacy 
relative to exclusive use of the reference biologic. Upon licensure by the FDA, an interchangeable biosimilar may be 
substituted for the reference product without the intervention of the health care provider who prescribed the reference product. 
Following approval of the interchangeable biosimilar product, the FDA may not grant interchangeability status for any second 
biosimilar until one year after the first commercial marketing of the first interchangeable biosimilar product. Congress clarified 
through FDORA that the FDA may approve multiple first interchangeable biosimilar biological products so long as the products 
are all approved on the first day on which such a product is approved as interchangeable with the reference product.  

A reference biological product is granted 12 years of exclusivity from the time of first licensure of the product, and the FDA 
will not accept an application for a biosimilar or interchangeable product based on the reference biological product until four 
years after the date of first licensure of the reference product. Even if a product is considered to be a reference product eligible 
for exclusivity, however, another company could market a competing version of that product if the FDA approves a full BLA 
for  such  product  containing  the  sponsor’s  own  preclinical  data  and  data  from  adequate  and  well‑controlled  clinical  trials  to 
demonstrate the safety, purity, and potency of their product. There have been recent government proposals to reduce the 12-year 
reference product exclusivity period, but none has been enacted to date. At the same time, since passage of the BPCIA, many 
states have passed laws or amendments to laws, which address pharmacy practices involving biosimilar products. 

Orphan drug designation and exclusivity 

Orphan drug designation in the United States is designed to encourage sponsors to develop products intended for treatment of 
rare  diseases  or  conditions.  In  the  United  States,  a  rare  disease  or  condition  is  statutorily  defined  as  a  condition  that  affects 
fewer than 200,000 individuals in the United States or that affects more than 200,000 individuals in the United States and for 
which  there  is  no  reasonable  expectation  that  the  cost  of  developing  and  making  available  the  product  for  the  disease  or 
condition will be recovered from sales of the product in the United States. 

Orphan drug designation qualifies a company for tax credits and potentially market exclusivity for seven years following the 
date of the product’s approval if granted by the FDA. An application for designation as an orphan product can be made any time 
prior to the filing of an application for approval to market the product. A product becomes an orphan when it receives orphan 
drug designation from the Office of Orphan Products Development at the FDA based on acceptable confidential requests. The 
product must then go through the review and approval process like any other product. 

27 

 
A sponsor may request orphan drug designation of a previously unapproved product or new orphan indication for an already 
marketed product. In addition, a sponsor of a product that is otherwise the same product as an already approved orphan drug 
may seek and obtain orphan drug designation for the subsequent product for the same rare disease or condition if it can present 
a  plausible  hypothesis  that  its  product  may  be  clinically  superior  to  the  first  approved  product.  More  than  one  sponsor  may 
receive orphan drug designation for the same product for the same rare disease or condition, but each sponsor seeking orphan 
drug designation must file a complete request for designation. 

If  a  product  with  orphan  designation  receives  the  first  FDA  approval  for  the  disease  or  condition  for  which  it  has  such 
designation  or  for  a  select  indication  or  use  within  the  rare  disease  or  condition  for  which  it  was  designated,  the  product 
generally will receive orphan drug exclusivity. Orphan drug exclusivity means that the FDA may not approve another sponsor’s 
marketing  application  for  the  same  product  for  the  same  disease  or  condition  for  seven  years,  except  in  certain  limited 
circumstances. If a product designated as an orphan drug ultimately receives marketing approval for an indication broader than 
what was designated in its orphan drug application, it may not be entitled to exclusivity. 

The period of market exclusivity begins on the date that the marketing application is approved by the FDA and applies only to 
the disease or condition for which the product has been designated. Orphan drug exclusivity will not bar approval of another 
product under certain circumstances, including if the company with orphan drug exclusivity is not able to meet market demand 
or the subsequent product is shown to be clinically superior to the approved product on the basis of greater efficacy or safety, or 
providing a major contribution to patient care. Under Omnibus legislation signed by President Trump on December 27, 2020, 
the requirement for a product to show clinical superiority applies to drug products that received orphan drug designation before 
enactment of amendments to the FDCA in 2017 but have not yet been approved by FDA. 

In  September  2021,  the  Court  of Appeals  for  the  11th  Circuit  held  that,  for  the  purpose  of  determining  the  scope  of  market 
exclusivity, the term “same disease or condition” in the statute means the designated “rare disease or condition” and could not 
be interpreted by the FDA to mean the “indication or use.” Thus, the court concluded, orphan drug exclusivity applies to the 
entire  designated  disease  or  condition  rather  than  the  “indication  or  use.” Although  there  have  been  legislative  proposals  to 
overrule this decision, they have not been enacted into law. On January 23, 2023, the FDA announced that, in matters beyond 
the scope of that court order, the FDA will continue to apply its existing regulations tying orphan-drug exclusivity to the uses or 
indications for which the orphan drug was approved. 

Pediatric exclusivity 

Pediatric  exclusivity  is  a  type  of  non‑patent  marketing  exclusivity  in  the  United  States  and,  if  granted,  provides  for  the 
attachment  of  an  additional  six  months  of  exclusivity.  For  biologic  products,  the  six  month  period  may  be  attached  to  any 
existing  regulatory  exclusivities  but  not  to  any  patent  terms.  The  conditions  for  pediatric  exclusivity  include  the  FDA’s 
determination that information relating to the use of a new product in the pediatric population may produce health benefits in 
that  population,  the  FDA  making  a  written  request  for  pediatric  clinical  trials,  and  the  sponsor  agreeing  to  perform,  and 
reporting on, the requested clinical trials within the statutory timeframe. This six‑month exclusivity may be granted if a sponsor 
submits pediatric data that fairly respond to a written request from the FDA for such data. The data do not need to show the 
product to be effective in the pediatric population studied. If reports of requested pediatric studies are submitted to and accepted 
by the FDA within the statutory time limits, whatever statutory  or  regulatory  periods of exclusivity or patents  that cover  the 
product are extended by six months. Although this is not a patent term extension, it effectively extends the regulatory period 
during which the FDA cannot approve another application. 

Patent term restoration and extension 

In the United States, a patent claiming a new product,  its  method  of  use or its  method  of  manufacture  may  be  eligible for  a 
limited patent term extension under the Hatch‑Waxman Act, which permits a patent extension of up to five years for patent term 
lost during product development and FDA regulatory review. Assuming grant of the patent for which the extension is sought, 
the  restoration  period  for  a  patent  covering  a  product  is  typically  one‑half  the  time  between  the  effective  date  of  the  IND 
involving human beings and the submission date of the BLA, plus the time between the submission date of the application and 
the ultimate approval date. Patent term restoration cannot be used to extend the remaining term of a patent past a total of 14 
years from the product’s approval date in the United States. Only one patent applicable to an approved product is eligible for 
the extension, and the application for the extension must be submitted prior to the expiration of the patent for which extension 
is sought. A patent that covers multiple products for which approval is sought can only be extended in connection with one of 
the approvals. The USPTO reviews and approves the application for any patent term extension in consultation with the FDA. 

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Companion diagnostics 

In August 2014, the FDA issued final guidance clarifying the requirements that will apply to approval of therapeutic products 
and  in  vitro  companion  diagnostics. According  to  the  guidance,  for  novel  biologics,  a  companion  diagnostic  device  and  its 
corresponding therapeutic should be approved or cleared contemporaneously by the FDA for the use indicated in the therapeutic 
product’s labeling. Approval or clearance of the companion diagnostic device will ensure that the device has been adequately 
evaluated  and  has  adequate  performance  characteristics  in  the  intended  population.  In  July  2016,  the  FDA  issued  a  draft 
guidance intended to assist sponsors of the therapeutic product and in vitro companion diagnostic device on issues related to co-
development of the products. 

The  2014  guidance  also  explains  that  a  companion  diagnostic  device  used  to  make  treatment  decisions  in  clinical  trials  of  a 
biologic product candidate generally will be considered an investigational device, unless it is employed for an intended use for 
which  the  device  is  already  approved  or  cleared.  If  used  to  make  critical  treatment  decisions,  such  as  patient  selection,  the 
diagnostic device generally will be considered a significant risk device under the FDA’s Investigational Device Exemption, or 
IDE, regulations. Thus, the sponsor of the diagnostic device will be required to comply with the IDE regulations. According to 
the guidance, if a diagnostic device and a product are to be studied together to support their respective approvals, both products 
can be studied in the same investigational study, if the study meets both the requirements of the IDE regulations and the IND 
regulations. The guidance provides that depending on the details of the study plan and subjects, a sponsor may seek to submit 
an IND application alone, or both an IND- and IDE-application. 

In  April  2020,  the  FDA  issued  additional  guidance  which  describes  considerations  for  the  development  and  labeling  of 
companion diagnostic devices to support the indicated uses of multiple biological oncology products, when appropriate. This 
guidance builds upon existing policy regarding the labeling of companion diagnostics. In its 2014 guidance, the FDA stated that 
if evidence is sufficient to conclude that the companion diagnostic is appropriate for use with a specific group of therapeutic 
products, the companion diagnostic’s intended use/indications for use should name the specific group of therapeutic products, 
rather than specific products. The 2020 guidance expands on the policy statement in the 2014 guidance by recommending that 
companion diagnostic developers consider a number of factors when determining whether their test could be developed, or the 
labeling for approved companion diagnostics could be revised through a supplement, to support a broader labeling claim such 
as use with a specific group of oncology therapeutic products (rather than listing an individual therapeutic product(s)). 

Under the FDCA, in vitro diagnostics, including companion diagnostics, are regulated as medical devices. In the United States, 
the  FDCA and its implementing regulations, and other federal  and state  statutes  and  regulations govern, among other things, 
medical  device  design  and  development,  preclinical  and  clinical  testing,  premarket  clearance  or  approval,  registration  and 
listing, manufacturing, labeling, storage, advertising and promotion, sales and distribution, export and import and post-market 
surveillance.  Unless  an  exemption  applies,  diagnostic  tests  require  pre-notification  marketing  clearance or  approval  from  the 
FDA prior to commercial distribution.The FDA previously has required in vitro companion diagnostics intended to select the 
patients who will respond to the product candidate to obtain pre-market approval, or PMA, simultaneously with approval of the 
therapeutic product candidate. The PMA process, including the gathering of clinical and preclinical data and the submission to 
and  review by  the FDA,  can take  several  years  or  longer. It  involves  a rigorous  premarket  review  during  which  the  sponsor 
must prepare and provide the FDA with reasonable assurance of the device’s safety and effectiveness and information about the 
device  and  its  components  regarding,  among  other  things,  device  design,  manufacturing  and  labeling.  PMA  applications  are 
subject to an application fee. PMA applications are subject to an application fee. For federal fiscal year 2023, the standard fee is 
$441,547 and the small business fee is $110,387. 

Healthcare compliance 

In the United States, biopharmaceutical manufacturers and their products are subject to extensive regulation at the federal and 
state level,  such as  laws intended to prevent fraud  and  abuse in the healthcare industry. Healthcare providers and third-party 
payors  play  a  primary  role  in  the  recommendation  and  prescription  of  pharmaceutical  products  that  are  granted  marketing 
approval. Arrangements with providers, consultants, third-party payors, and customers are subject to broadly applicable fraud 
and  abuse,  anti-kickback,  false  claims  laws,  reporting  of  payments  to  healthcare  providers  and  patient  privacy  laws  and 
regulations  and  other  healthcare  laws  and  regulations  that  may  constrain  our  business  and/or  financial  arrangements. 
Restrictions  under  applicable  federal  and  state  healthcare  laws  and  regulations,  including  certain  laws  and  regulations 
applicable only if we have marketed products, include the following: 

• 

federal  false  claims,  false  statements  and  civil  monetary  penalties  laws  prohibiting,  among  other  things,  any person 
from knowingly presenting, or causing to be presented, a false claim for payment of government funds or knowingly 
making, or causing to be made, a false statement to get a false claim paid;  

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• 

• 

• 

• 

• 

• 

• 

federal healthcare program anti-kickback law, which prohibits, among other things, persons from offering, soliciting, 
receiving  or  providing  remuneration,  directly  or  indirectly,  to  induce  either  the  referral  of  an  individual  for,  or  the 
purchasing or ordering of, a good or service for which payment may be made under federal healthcare programs such 
as Medicare and Medicaid;  

the  federal  Health  Insurance  Portability  and  Accountability  Act  of  1996,  or  HIPAA,  which,  in  addition  to  privacy 
protections  applicable  to  healthcare  providers  and  other  entities,  prohibits  executing  a  scheme  to  defraud  any 
healthcare benefit program or making false statements relating to healthcare matters;  

federal laws that require pharmaceutical manufacturers to report certain calculated product prices to the government or 
provide certain discounts or rebates to government authorities or private entities, often as a condition of reimbursement 
under government healthcare programs;  

federal Open Payments (or federal “sunshine” law), which requires pharmaceutical and medical device companies to 
monitor  and  report  certain  financial  interactions  with  certain  healthcare  providers  to  the  Center  for  Medicare  & 
Medicaid  Services,  or  CMS,  within  the  HHS  for  re-disclosure  to  the  public,  as  well  as  ownership  and  investment 
interests held by physicians and their immediate family members;  

federal consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities 
that potentially harm consumers; 

analogous  state  laws  and  regulations,  including:  state  anti-kickback  and  false  claims  laws;  state  laws  requiring 
pharmaceutical  companies  to  comply  with  specific  compliance  standards,  restrict  financial  interactions  between 
pharmaceutical companies and healthcare providers or require pharmaceutical companies to report information related 
to  payments  to  health  care  providers  or  marketing  expenditures;  and  state  laws  governing  privacy,  security  and 
breaches of health information in certain circumstances, many of which differ from each other in significant ways and 
often are not preempted by HIPAA, thus complicating compliance efforts; and 

laws and regulations prohibiting bribery and corruption such as the Foreign Corrupt Practices Act, which, among other 
things, prohibits U.S. companies and their employees and agents from authorizing, promising, offering, or providing, 
directly  or  indirectly,  corrupt  or  improper  payments  or  anything  else  of  value  to  foreign  government  officials, 
employees  of  public  international  organizations  or  foreign  government-owned  or  affiliated  entities,  candidates  for 
foreign public office, and foreign political parties or officials thereof. 

Violations  of  these  laws  are  punishable  by  criminal  and/or  civil  sanctions,  including,  in  some  instances,  exclusion  from 
participation in federal and state health care programs, such as Medicare and Medicaid. Ensuring compliance is time consuming 
and  costly.  Similar  healthcare  laws  and  regulations  exist  in  the  European  Union  and  other  jurisdictions,  including  reporting 
requirements detailing interactions with and payments to healthcare providers and laws governing the privacy and security of 
personal information. 

Healthcare reform  

A primary trend in the U.S. healthcare industry and elsewhere is cost containment. There have been a number of federal and 
state proposals during the last few years regarding the pricing of pharmaceutical products, limiting coverage and reimbursement 
for medical products and other changes to the healthcare system in the United States. 

In March 2010, the United States Congress enacted the Patient Protection and Affordable Care Act, as amended by the Health 
Care and Education Reconciliation Act of 2010, or collectively the PPACA, which, among other things, includes changes to the 
coverage and payment for pharmaceutical products under government healthcare programs. Other legislative changes have been 
proposed  and  adopted  since  the  PPACA  was  enacted.  In August  2011,  the  Budget  Control Act  of  2011,  among  other things, 
created  measures  for  spending  reductions  by  Congress.  A  Joint  Select  Committee  on  Deficit  Reduction,  tasked  with 
recommending a targeted deficit reduction of at least $1.2 trillion for the years 2013 through 2021, was unable to reach required 
goals,  thereby  triggering  the  legislation’s  automatic  reduction  to  several  government  programs.  These  changes  included 
aggregate reductions to Medicare payments to providers of up to 2% per fiscal year, which went into effect in April 2013 and 
will remain in effect through 2031. These Medicare sequester reductions were suspended and reduced through the end of June 
2022, with the full 2% cut resuming thereafter. 

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Since enactment of the PPACA, there have been, and continue to be, numerous legal challenges and Congressional actions to 
repeal and replace provisions of the law. For example, with enactment of the Tax Cuts and Jobs Act of 2017, or the Tax Act, 
which was signed by President Trump on December 22, 2017, Congress repealed the “individual mandate.” The repeal of this 
provision, which requires most Americans to carry a minimal level of health insurance, became effective in 2019. On December 
14, 2018, a U.S. District Court judge in the Northern District of Texas ruled that the individual mandate portion of the PPACA 
is an essential and inseverable feature of the PPACA, and therefore because the mandate was repealed as part of the Tax Act, the 
remaining provisions of the PPACA are invalid as well. The U.S. Supreme Court heard this case on November 10, 2020 and, on 
June 17, 2021, dismissed this action after finding that the plaintiffs do not have standing to challenge the constitutionality of the 
ACA. Litigation and legislation over the PPACA are likely to continue, with unpredictable and uncertain results. 

The  Trump  Administration  also  took  executive  actions  to  undermine  or  delay  implementation  of  the  PPACA,  including 
directing  federal  agencies  with  authorities  and  responsibilities  under  the  PPACA  to  waive,  defer,  grant  exemptions  from,  or 
delay the implementation of any provision of the PPACA that would impose a fiscal or regulatory burden on states, individuals, 
healthcare providers, health insurers, or manufacturers of pharmaceuticals or medical devices. On January 28, 2021, however, 
President Biden rescinded those orders and issued a new executive order that directs federal agencies to reconsider rules and 
other policies that limit access to healthcare, and consider actions that will protect and strengthen that access. Under this order, 
federal  agencies  are  directed  to  re-examine:  policies  that  undermine  protections  for  people  with  pre-existing  conditions, 
including  complications  related  to  COVID‑19;  demonstrations  and  waivers  under  Medicaid  and  the  PPACA  that  may  reduce 
coverage or undermine the programs, including work requirements; policies that undermine the Health Insurance Marketplace 
or  other  markets  for  health  insurance;  policies  that  make  it  more  difficult  to  enroll  in  Medicaid  and  under  the  PPACA;  and 
policies that reduce affordability of coverage or financial assistance, including for dependents. 

Pharmaceutical prices 

The  prices  of  prescription  pharmaceuticals  have  also  been  the  subject  of  considerable discussion  in  the  United  States. There 
have been several recent U.S. congressional inquiries, as well as proposed and enacted state and federal legislation designed to, 
among  other  things,  bring  more  transparency  to  pharmaceutical  pricing,  review  the  relationship  between  pricing  and 
manufacturer  patient  programs,  and  reduce  the  costs  of  pharmaceuticals  under  Medicare  and  Medicaid.  In  2020,  President 
Trump issued several executive orders intended to lower the costs of prescription products and certain provisions in these orders 
have  been  incorporated  into  regulations. These  regulations include  an  interim  final  rule  implementing  a  most  favored  nation 
model  for  prices  that  would  tie  Medicare  Part  B  payments  for  certain  physician-administered  pharmaceuticals  to  the  lowest 
price  paid  in  other  economically  advanced  countries,  effective  January  1,  2021.  That  rule,  however,  has  been  subject  to  a 
nationwide preliminary injunction and, on December 29, 2021, CMS issued a final rule to rescind it. With issuance of this rule, 
CMS stated that it will explore all options to incorporate value into payments for Medicare Part B pharmaceuticals and improve 
beneficiaries' access to evidence-based care. 

In addition, in October 2020, the HHS and the FDA published a final rule allowing states and other entities to develop a Section 
804 Importation Program, or SIP, to import certain prescription products from Canada into the United States. The final rule is 
currently the subject of ongoing litigation, but at least six states (Vermont, Colorado, Florida, Maine, New Mexico, and New 
Hampshire)  have  passed  laws  allowing  for  the  importation  of  products  from  Canada  with  the  intent  of  developing  SIPs  for 
review and approval by the FDA. Further, on November 20, 2020, HHS finalized a regulation removing safe harbor protection 
for  price  reductions  from  pharmaceutical  manufacturers  to  plan  sponsors  under  Part  D,  either  directly  or  through  pharmacy 
benefit managers, unless the price reduction is required by law. The implementation of the rule has been delayed by the Biden 
administration  from  January  1,  2022  to  January  1,  2023  in  response  to  ongoing  litigation.  The  rule  also  creates  a  new  safe 
harbor  for  price  reductions  reflected  at  the  point-of-sale,  as  well  as  a  new  safe  harbor  for  certain  fixed  fee  arrangements 
between  pharmacy  benefit  managers  and  manufacturers,  the  implementation  of  which  has  been  delayed  by  the  Biden 
administration until January 1, 2026 by the Infrastructure Investment and Jobs Act. 

On  July  9,  2021,  President  Biden  signed  Executive  Order  14063,  which  focuses  on,  among  other  things,  the  price  of 
pharmaceuticals.  The  Order  directs  the  HHS  to  create  a  plan  within  45  days  to  combat  “excessive  pricing  of  prescription 
pharmaceuticals and enhance domestic pharmaceutical supply chains, to reduce the prices paid by the federal government for 
such pharmaceuticals, and to address the recurrent problem of price gouging.” On September 9, 2021, HHS released its plan to 
reduce  pharmaceutical  prices.  The  key  features  of  that  plan  are  to:  (a)  make  pharmaceutical  prices  more  affordable  and 
equitable  for  all  consumers  and  throughout  the  health  care  system  by  supporting  pharmaceutical  price  negotiations  with 
manufacturers; (b) improve and promote competition throughout the prescription pharmaceutical industry by supporting market 
changes that strengthen supply chains,  promote biosimilars, and  increase transparency;  and  (c)  foster scientific innovation  to 

31 

 
promote better healthcare and improve health by supporting public and private research and making sure that market incentives 
promote discovery of valuable and accessible new treatments.  

More recently, on August 16, 2022, the Inflation Reduction Act of 2022, or IRA, was signed into law by President Biden. The 
new legislation has implications for Medicare Part D, which is a program available to individuals who are entitled to Medicare 
Part A or enrolled in Medicare Part B to  give them the option of paying  a  monthly premium for outpatient prescription drug 
coverage. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare 
beginning in 2026, with prices that can be negotiated subject to a cap; imposes rebates under Medicare Part B and Medicare 
Part  D  to  penalize  price  increases  that  outpace  inflation  first  due  in  2023;  and  replaces  the  Part  D  coverage  gap  discount 
program  with  a  new discounting  program  beginning  in  2025. The  IRA  permits  the  Secretary  of  HHS  to  implement many  of 
these provisions through guidance, as opposed to regulation, for the initial years.  

Specifically,  with  respect  to  price  negotiations,  Congress  authorized  Medicare  to  negotiate  lower  prices  for  certain  costly 
single-source drug and biologic products that do not have competing generics or biosimilars and are reimbursed under Medicare 
Part B and Part D. CMS may negotiate prices for ten high-cost drugs paid for by Medicare Part D starting in 2026, followed by 
15 additional Part D drugs in 2027, 15 additional Part B or Part D drugs in 2028, and 20 additional Part B or Part D drugs in 
2029  and  beyond. This  provision  applies  to  drug products  that  have been  approved  for  at  least  nine  years  and  biologics  that 
have been licensed for 13 years, but it does not apply to drugs and biologics that have been approved for a single rare disease or 
condition. Further, the legislation subjects drug manufacturers to civil monetary penalties and a potential excise tax for failing 
to comply with the legislation by offering a price that is not equal to or less than the negotiated “maximum fair price” under the 
law or for taking price increases that exceed inflation. The legislation also requires manufacturers to pay rebates for drugs in 
Medicare  Part  D  whose  price  increases  exceed  inflation.  The  new  law  also  caps  Medicare  out-of-pocket  drug  costs  at  an 
estimated $4,000 a year in 2024 and, thereafter beginning in 2025, at $2,000 a year. 

At the state level, individual states are increasingly aggressive in passing legislation and implementing regulations designed to 
control  pharmaceutical  and  biological  product  pricing,  including  price  or  patient  reimbursement  constraints,  discounts, 
restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to 
encourage  importation  from  other  countries  and  bulk  purchasing.  A  number  of  states,  for  example,  require  pharmaceutical 
manufacturers  and  other  entities  in  the  supply  chain,  including  health  carriers,  pharmacy  benefit  managers,  wholesale 
distributors,  to  disclose  information  about  pricing  of  pharmaceuticals.  In  addition,  regional  healthcare  organizations  and 
individual hospitals are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers 
will be included in their prescription pharmaceutical and other healthcare programs. These measures could reduce the ultimate 
demand  for  our  products,  once  approved,  or put pressure  on  our product  pricing. We  expect  that  additional  state  and  federal 
healthcare  reform  measures  will  be  adopted  in  the  future,  any  of  which  could  limit  the  amounts  that  federal  and  state 
governments will pay for healthcare products and services, which could result in reduced demand for our product candidates or 
additional pricing pressures. 

Federal and state data privacy laws 

There  are  multiple  privacy  and  data  security  laws  that  may  impact  our  business  activities,  in  the  United  States  and  in  other 
countries where we conduct trials or where we may do business in the future. These laws are evolving and may increase both 
our obligations and our regulatory risks in the future. In the health care industry generally, under HIPAA, the HHS has issued 
regulations  to  protect  the  privacy  and  security  of  protected  health  information,  or  PHI,  used  or  disclosed  by  covered  entities 
including certain healthcare providers, health plans and healthcare clearinghouses. HIPAA also regulates standardization of data 
content,  codes  and  formats  used  in  healthcare  transactions  and  standardization  of  identifiers  for  health  plans  and  providers. 
HIPAA also imposes certain obligations on the business associates of covered entities that obtain protected health information 
in providing services to or on behalf of covered entities. HIPAA may apply to us in certain circumstances and may also apply to 
our business  partners  in  ways  that  may  impact  our  relationships  with  them.  Our  clinical  trials  are  regulated  by  the  Common 
Rule, which also includes specific privacy-related provisions. In addition to federal privacy regulations, there are a number of 
state laws governing confidentiality and  security of health  information  that  may  be  applicable  to  our business.  In addition to 
possible federal civil and criminal penalties for HIPAA violations, state attorneys general are authorized to file civil actions for 
damages or injunctions in federal courts to enforce HIPAA and seek attorney’s fees and costs associated with pursuing federal 
civil actions. In addition, state attorneys general (along  with  private  plaintiffs)  have brought  civil  actions  seeking  injunctions 
and  damages  resulting  from  alleged  violations  of  HIPAA’s  privacy  and  security  rules.  State  attorneys  general  also  have 
authority to enforce state privacy and security laws. New laws and regulations governing privacy and security may be adopted 
in the future as well. 

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At  the  state  level,  California  has  enacted  legislation  that  has  been  dubbed  the  first  “GDPR-like”  law  in  the  United  States. 
Known as the California Consumer Privacy Act, or CCPA, it creates new individual privacy rights for consumers (as that word 
is  broadly  defined  in  the  law)  and  places  increased  privacy  and  security  obligations  on  entities  handling  personal  data  of 
consumers  or  households.  The  CCPA  went  into  effect  on  January  1,  2020  and  requires  covered  companies  to  provide  new 
disclosures to California consumers, provide such consumers new ways to opt-out of certain sales of personal information, and 
allow for a new cause of action for data breaches. Additionally,  effective  starting on  January 1, 2023,  the  California  Privacy 
Rights  Act,  or  CPRA,  significantly  modified  the  CCPA,  including  by  expanding  consumers’  rights  with  respect  to  certain 
sensitive personal information. The CPRA also creates a new state agency that will be vested with authority to implement and 
enforce the CCPA and the CPRA. The CCPA and CPRA could impact our business activities depending on how it is interpreted 
and exemplifies the vulnerability of our business to not only cyber threats but also the evolving regulatory environment related 
to personal data and individually identifiable health information. These provisions may apply to some of our business activities. 
In addition, other states, including Virginia and Colorado, already have passed state privacy laws and other states will likely be 
considering similar laws in the near future.  

Because of the breadth of these laws and the narrowness of the statutory exceptions and regulatory safe harbors available under 
such  laws,  it  is  possible  that  some  of  our  current  or  future  business  activities,  including  certain  clinical  research,  sales  and 
marketing practices and the provision of certain items and services to our customers, could be subject to challenge under one or 
more  of  such  privacy  and  data  security  laws.  The  heightening  compliance  environment  and  the  need  to  build  and  maintain 
robust and secure systems to comply with different privacy compliance and/or reporting requirements in multiple jurisdictions 
could increase the possibility that a healthcare company may fail to comply fully with one or more of these requirements. If our 
operations  are  found  to  be  in  violation  of  any  of  the  privacy  or  data  security  laws  or  regulations  described  above  that  are 
applicable to us, or any other laws that apply to us, we may be subject to penalties, including potentially significant criminal, 
civil  and  administrative  penalties,  damages,  fines,  contractual  damages,  reputational  harm,  diminished  profits  and  future 
earnings, additional reporting requirements and/or oversight if we become subject to a consent decree or similar agreement to 
resolve  allegations  of  non-compliance  with  these  laws,  and  the  curtailment  or  restructuring  of  our  operations,  any  of  which 
could adversely affect our ability to operate our business and our results of operations. To the extent that any product candidates 
we may develop, once approved, are sold in a foreign country, we may be subject to similar foreign laws. 

Approval and regulation of medical products in the European Union 

In addition to regulations in the United States, we will be subject to a variety of foreign regulations governing clinical trials and 
commercial sales and distribution of our products outside of the United States. Whether or not we obtain FDA approval for a 
product candidate, we must obtain approval by the comparable regulatory authorities of foreign countries or economic areas, 
such as the 27-member European Union, before we may commence clinical trials or market products in those countries or areas. 
In  the  European  Union,  our  product  candidates  also  may  be  subject  to  extensive  regulatory  requirements. As  in  the  United 
States, medicinal products can be marketed only if a marketing authorization from the competent regulatory agencies has been 
obtained. Similar to the United States, the various phases of preclinical and clinical research in the European Union are subject 
to significant regulatory controls. 

With the exception of the European Union and European Economic Area, or EEA, applying the harmonized regulatory rules for 
medicinal products, the approval process and requirements governing the conduct of clinical trials, product licensing, pricing 
and  reimbursement  vary  greatly  between  countries  and  jurisdictions  and  can  involve  additional  testing  and  additional 
administrative review periods. The time required to obtain approval in other countries and jurisdictions might differ from and 
be  longer  than  that  required  to  obtain  FDA  approval.  Regulatory  approval  in  one  country  or  jurisdiction  does  not  ensure 
regulatory  approval  in  another,  but  a  failure  or  delay  in  obtaining  regulatory  approval  in  one  country  or  jurisdiction  may 
negatively impact the regulatory process in others. 

Clinical trials 

On January 31, 2022, the new Clinical Trials Regulation (EU) No 536/2014, or the Clinical Trials Regulation, became effective 
in the European Union and replaced the prior Clinical Trials Directive 2001/20/EC. The new regulation aims at simplifying and 
streamlining the authorization, conduct and transparency of clinical trials in the European Union. Under the new coordinated 
procedure for the approval of clinical trials, the sponsor of a clinical trial to be conducted in more than one Member State of the 
European Union, or EU Member State, will only be required to submit a single application for approval. The submission will be 
made through the Clinical Trials Information System, a new clinical trials portal overseen by the EMA and available to clinical 
trial  sponsors,  competent  authorities  of  the EU  Member  States  and  the  public.  Beyond  streamlining  the  process,  the Clinical 
Trials  Regulation  includes  a  single  set  of  documents  to  be  prepared  and  submitted  for  the  application  as  well  as  simplified 
reporting procedures for clinical trial sponsors, and a harmonized procedure for the assessment of applications for clinical trials, 

33 

 
which is divided into two parts. Part I is assessed by the competent authorities of all EU Member States in which an application 
for authorization of a clinical trial has been submitted where EU Member States are concerned. Part II is assessed separately by 
each EU Member State concerned. Strict deadlines have been established for the assessment of clinical trial applications. The 
role  of  the  relevant  ethics  committees  in  the  assessment  procedure  will  continue  to  be  governed  by  the  national  law  of  the 
concerned EU Member State. However, overall related timelines will be defined by the Clinical Trials Regulation. 

The new regulation did not change the preexisting requirement that a sponsor must obtain prior approval from the competent 
national  authority  of  the  EU Member  State  in  which  the  clinical  trial  is  to  be  conducted.  If  the  clinical  trial  is  conducted  in 
different EU Member States, the competent authorities in each of these EU Member States must provide their approval for the 
conduct of the clinical trial. Furthermore, the sponsor may only start a clinical trial at a specific clinical site after the applicable 
ethics committee has issued a favorable opinion. 

Parties conducting certain clinical trials must, as in the United States, post clinical trial information in the European Union at 
the EudraCT website: https://eudract.ema.europa.eu. 

Marketing authorization in the European Union 

Marketing  authorization  applications,  or  MAAs,  can  be  filed  either  under  the  so-called  centralized  or  national  authorization 
procedures, albeit through the mutual recognition or decentralized procedure for a product to be authorized in more than one 
EU Member State. 

The  centralized  procedure  provides  for  the  grant  of  a  single  marketing  authorization  following  a  favorable  opinion  by  the 
European Medicines Agency, or EMA, that is  valid in all  EU Member States, as  well  as Iceland,  Liechtenstein and Norway, 
which  are  part  of  the  EEA.  The  centralized  procedure  is  compulsory  for  medicines  produced  by  specified  biotechnological 
processes, products designated as orphan medicinal products, advanced-therapy medicines (such as gene-therapy, somatic cell-
therapy  or  tissue-engineered  medicines)  and  products  with  a  new  active  substance  indicated  for  the  treatment  of  specified 
diseases,  such  as  HIV/  AIDS,  cancer,  diabetes,  neurodegenerative  disorders  or  autoimmune  diseases  and  other  immune 
dysfunctions  and  viral  diseases.  The  centralized  procedure  is  optional  for  products  that  represent  a  significant  therapeutic, 
scientific  or  technical  innovation,  or  whose  authorization  would  be  in  the  interest  of  public  health.  Under  the  centralized 
procedure  the  maximum  timeframe  for  the  evaluation  of  an  MAA  by  the  EMA  is  210  days,  excluding  clock  stops,  when 
additional  written  or  oral  information  is  to  be  provided  by the  sponsor  in  response  to  questions  asked  by  the  Committee  for 
Medicinal Products for Human Use, or the CHMP. Accelerated assessment might be granted by the CHMP in exceptional cases, 
when a medicinal product is expected to be of a major public health interest, particularly from the point of view of therapeutic 
innovation. The timeframe for the evaluation of an MAA under the accelerated assessment procedure is of 150 days, excluding 
stop-clocks. 

There  are  also  two  other  possible  routes  to  authorize  medicinal  products  in  several  EU  countries,  which  are  available  for 
investigational medicinal products that fall outside the scope of the centralized procedure: 

•  Decentralized  procedure.  Using  the decentralized  procedure,  a  sponsor  may  apply  for  simultaneous  authorization  in 
more than one EU country of medicinal products that have not yet been authorized in any EU country and that do not 
fall within the mandatory scope of the centralized procedure. The sponsor may choose a member state as the reference 
member State to lead the scientific evaluation of the application. 

•  Mutual recognition procedure. In the mutual recognition procedure, a medicine is first authorized in one EU Member 
State (which acts as the reference member state), in accordance with the national procedures of that country. Following 
this, further marketing authorizations can be progressively sought from other EU countries in a procedure whereby the 
countries concerned agree to recognize the validity of the original, national marketing authorization produced by the 
reference member state. 

Under the above-described procedures, before granting the marketing authorization, the EMA or the competent authorities of 
the Member States of the EEA make an assessment of the risk-benefit balance of the product on the basis of scientific criteria 
concerning its quality, safety and efficacy. 

Conditional approval 

In  particular  circumstances,  EU  legislation  (Article  14–a  Regulation  (EC)  No  726/2004  (as  amended  by  Regulation  (EU) 
2019/5 and Regulation (EC) No 507/2006 on Conditional Marketing Authorizations for Medicinal Products for Human  Use) 
enables sponsors to obtain a conditional marketing authorization prior to obtaining the comprehensive clinical data required for 

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an application for a full marketing authorization. Such conditional approvals may be granted for product candidates (including 
medicines  designated  as  orphan  medicinal  products)  if  (1) the  product  candidate  is  intended  for  the  treatment,  prevention  or 
medical  diagnosis  of  seriously  debilitating  or  life-threatening  diseases;  (2)  the  product  candidate  is  intended  to  meet  unmet 
medical  needs  of  patients;  (3)  a  marketing  authorization  may  be  granted  prior  to  submission  of  comprehensive  clinical  data 
provided  that  the  benefit  of  the  immediate  availability  on the  market  of  the  medicinal  product  concerned  outweighs  the  risk 
inherent in the fact that additional data are still required; (4) the risk-benefit balance of the product candidate is positive, and (5) 
it  is  likely  that  the  sponsor  will  be  in  a  position  to  provide  the  required  comprehensive  clinical  trial  data.  A  conditional 
marketing  authorization  may  contain  specific  obligations  to  be  fulfilled  by  the  marketing  authorization  holder,  including 
obligations  with  respect  to  the  completion  of  ongoing  or  new  clinical  trials  and  with  respect  to  the  collection  of 
pharmacovigilance data. Conditional marketing authorizations are valid for one year, and may be renewed annually, if the risk-
benefit  balance  remains  positive,  and  after  an  assessment  of  the  need  for  additional  or  modified  conditions  or  specific 
obligations. The timelines for the centralized procedure described above also apply with respect to the review by the CHMP of 
applications for a conditional marketing authorization. 

Pediatric trials 

Prior  to  obtaining  a  marketing  authorization  in  the  European  Union,  sponsors  have  to  demonstrate  compliance  with  all 
measures included in an EMA-approved Pediatric Investigation Plan,  or  PIP, covering  all  subsets  of  the pediatric population, 
unless the EMA has granted a product-specific waiver, a class waiver or a deferral for one or more of the measures included in 
the PIP. The respective requirements for all marketing authorization procedures are set forth in Regulation (EC) No 1901/2006, 
which is referred to as the Pediatric Regulation. This requirement also applies when a company wants to add a new indication, 
pharmaceutical form or route of administration for a medicine that is already authorized. The Pediatric Committee of the EMA, 
or PDCO, may grant deferrals for some medicines, allowing a company to delay development of the medicine in children until 
there  is  enough  information  to  demonstrate  its  effectiveness  and  safety  in  adults.  The  PDCO  may  also  grant  waivers  when 
development of a medicine in children is not needed or is not appropriate because (a) the product is likely to be ineffective or 
unsafe in part or all of the pediatric population; (b) the disease or condition occurs only in adult population; or (c) the product 
does  not  represent  a  significant  therapeutic  benefit  over  existing  treatments  for  pediatric  population.  Before  a  marketing 
authorization  application  can  be  filed,  or  an  existing  marketing  authorization  can  be  amended,  the  EMA  determines  that 
companies actually comply with the agreed studies and measures listed in each relevant PIP. 

PRIME designation 

In March 2016, the EMA launched an initiative to  facilitate  development  of product  candidates  in indications,  often  rare,  for 
which  few  or  no  therapies  currently  exist.  The  PRIority  MEdicines,  or  PRIME,  scheme  is  intended  to  encourage  product 
development  in  areas  of  unmet  medical  need  and  provides  accelerated  assessment  of  products  representing  substantial 
innovation  reviewed  under  the  centralized  procedure.  Products  from  small-  and  medium-sized  enterprises,  or  SMEs,  may 
qualify for earlier entry into the PRIME scheme than larger companies. Many benefits accrue to sponsors of product candidates 
with  PRIME  designation,  including  but  not  limited  to,  early  and  proactive  regulatory  dialogue  with  the  EMA,  frequent 
discussions  on  clinical  trial  designs  and  other  development  program  elements,  and  accelerated  marketing  authorization 
application  assessment  once  a  dossier  has  been  submitted.  Importantly,  a  dedicated  agency  contact  and  rapporteur  from  the 
CHMP or Committee for Advanced Therapies are appointed early in the PRIME scheme, facilitating increased understanding of 
the product at EMA’s Committee level. A kick-off meeting initiates these relationships and includes a team of multidisciplinary 
experts at the EMA to provide guidance to the sponsor on the overall development and regulatory strategies. 

Periods of authorization and renewals 

A marketing authorization is valid for five years in principle and the marketing authorization may be renewed after five years 
on the basis of a re-evaluation of the risk-benefit balance by the EMA or by the competent authority of the authorizing member 
state.  To  this  end,  the marketing  authorization  holder  must  provide  the  EMA  or  the  competent  authority  with  a  consolidated 
version of the file in respect of quality, safety and efficacy, including all variations introduced since the marketing authorization 
was  granted,  at  least  nine  months  before  the  marketing  authorization  ceases  to  be  valid.  Once  renewed,  the  marketing 
authorization is valid for an unlimited period, unless the European Commission or the competent authority decides, on justified 
grounds  relating  to  pharmacovigilance,  to  proceed  with  one  additional  five-year  renewal.  Any  authorization  which  is  not 
followed  by  the  actual  placing  of  the  product  on  the  EU  market  (in  case  of  centralized  procedure)  or  on  the  market  of  the 
authorizing member state within three years after authorization ceases to be valid (the so-called sunset clause). 

35 

 
Regulatory requirements after marketing authorization  

As  in  the  United  States,  both  marketing  authorization  holders  and  manufacturers  of  medicinal  products  are  subject  to 
comprehensive regulatory oversight by the EMA and the competent authorities of the individual EU Member States both before 
and after grant of the manufacturing and marketing authorizations. The holder of an EU marketing authorization for a medicinal 
product  must,  for  example,  comply  with  EU  pharmacovigilance  legislation  and  its  related  regulations  and  guidelines  which 
entail  many  requirements  for  conducting  pharmacovigilance,  or  the  assessment  and  monitoring  of  the  safety  of  medicinal 
products. The manufacturing process for medicinal products in the European Union is also highly regulated and regulators may 
shut down manufacturing facilities that they believe do not comply with regulations. Manufacturing requires a manufacturing 
authorization, and the manufacturing authorization holder must comply with various requirements set out in the applicable EU 
laws,  including  compliance  with  EU  cGMP  standards  when  manufacturing  medicinal  products  and  active  pharmaceutical 
ingredients. 

In the European Union, the advertising and promotion of approved products are subject to EU Member States’ laws governing 
promotion of medicinal products, interactions with clinicians, misleading and comparative advertising and unfair commercial 
practices. In addition, other legislation adopted by individual EU Member States may apply to the advertising and promotion of 
medicinal  products.  These  laws  require  that  promotional  materials  and  advertising  in  relation  to  medicinal  products  comply 
with  the  product’s  Summary of  Product  Characteristics,  or  SmPC,  as  approved  by  the  competent  authorities.  Promotion of  a 
medicinal product that does not comply with the SmPC is considered to constitute off-label promotion, which is prohibited in 
the European Union.  

Regulatory exclusivity 

In  the  European  Union,  new  products  authorized  for  marketing  (i.e.,  reference  products)  qualify  for  eight  years  of  data 
exclusivity  and  an  additional  two  years  of  market  exclusivity  upon  marketing  authorization.  The  data  exclusivity  period 
prevents generic sponsors from relying on the preclinical and clinical trial data contained in the dossier of the reference product 
when applying for a generic marketing authorization  in  the  European Union  during a  period  of  eight  years  from the date on 
which the reference product was first authorized in the European Union. The market exclusivity period prevents a successful 
generic  sponsor  from  commercializing  its  product  in  the  European  Union  until  ten  years  have  elapsed  from  the  initial 
authorization  of  the  reference  product  in  the  European  Union.  The  ten-year  market  exclusivity  period  can  be  extended  to  a 
maximum  of  eleven  years  if,  during  the  first  eight  years  of  those  ten  years,  the  marketing  authorization  holder  obtains  an 
authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are 
held to bring a significant clinical benefit in comparison with existing therapies. 

Orphan drug designation and exclusivity 

The criteria for designating an orphan medicinal product in the European Union are similar in principle to those in the United 
States. Under Article 3 of Regulation (EC) 141/2000, a medicinal product may be designated as orphan if (1) it is intended for 
the diagnosis, prevention or treatment of a life- threatening or chronically debilitating condition, (2) either (a) such condition 
affects no more than five in 10,000 persons in the European Union when the application is made, or (b) the product, without the 
benefits derived from orphan status, would not generate sufficient return in the European Union to justify investment and (3) 
there  exists  no  satisfactory  method  of  diagnosis,  prevention  or  treatment  of  such  condition  authorized  for  marketing  in  the 
European Union, or if such a method exists, the product will be of significant benefit to those affected by the condition. The 
term  ‘significant  benefit’  is  defined  in  Regulation  (EC)  847/2000  to  mean  a  clinically  relevant  advantage  or  a  major 
contribution to patient care. 

Orphan medicinal products are eligible for financial incentives such as reduction of fees or fee waivers and are, upon grant of a 
marketing authorization, entitled to ten years of market exclusivity for the approved therapeutic indication. During this ten year 
market exclusivity period, the EMA or the competent authorities of the Member States of the EEA, cannot accept an application 
for a marketing authorization for a similar medicinal product for the same indication. A similar medicinal product is defined as 
a medicinal product containing a similar active substance or substances as contained in an authorized orphan medicinal product, 
and which is intended for the same therapeutic indication. The application for orphan designation must be submitted before the 
application for marketing authorization. The sponsor will receive a fee reduction for the marketing authorization application if 
the  orphan designation has been granted, but not if the designation is  still  pending  at  the  time  the  marketing authorization  is 
submitted. Orphan designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval 
process. 

The  ten-year  market  exclusivity  in  the  European  Union  may  be  reduced  to  six  years  if,  at  the  end  of  the  fifth  year,  it  is 
established  that  the  product  no  longer  meets  the  criteria  for  orphan  designation,  for  example,  if  the  product  is  sufficiently 

36 

 
profitable not to justify maintenance of market exclusivity. Additionally, marketing authorization may be granted to a similar 
product for the same indication at any time if: (1) the second sponsor can establish that its product, although similar, is safer, 
more effective or otherwise clinically superior; (2) the sponsor consents to a second orphan medicinal product application; or 
(3) the sponsor cannot supply enough orphan medicinal product. 

Pediatric exclusivity 

If a sponsor obtains a marketing authorization in all EU Member States, or a marketing authorization granted in the centralized 
procedure  by  the  European  Commission,  and  the  trial  results  for  the  pediatric  population  are  included  in  the  product 
information,  even  when  negative,  the  medicine  is  then  eligible  for  an  additional  six-month  period  of  qualifying  patent 
protection  through  extension  of  the  term  of  the  Supplementary  Protection  Certificate,  or  SPC,  or  alternatively  a  one  year 
extension of the regulatory market exclusivity from ten to eleven years, as selected by the marketing authorization holder. 

Patent term extensions 

The European Union also provides for patent term extension through Supplementary Protection Certificates, or SPCs. The rules 
and requirements for obtaining a SPC are similar to those in the United States. An SPC may extend the term of a patent for up 
to  five  years  after  its  originally  scheduled  expiration  date  and  can  provide  up  to  a  maximum  of  fifteen  years  of  marketing 
exclusivity  for  a  product.  In  certain  circumstances,  these  periods  may  be  extended  for  six  additional  months  if  pediatric 
exclusivity  is  obtained.  Although  SPCs  are  available  throughout  the  European  Union,  sponsors  must  apply  on  a 
country‑by‑country basis. Similar patent term extension rights exist in certain other foreign jurisdictions outside the European 
Union. 

Reimbursement and pricing of prescription pharmaceuticals 

In the European Union, similar political, economic and regulatory developments to those in the United States may affect our 
ability  to  profitably  commercialize  our  product  candidates,  if  approved.  In  markets  outside  of  the  United  States  and  the 
European  Union,  reimbursement  and  healthcare  payment  systems  vary  significantly  by  country  and  many  countries  have 
instituted  price  ceilings  on  specific  products  and  therapies.  In  many  countries,  including  those  of  the  European  Union,  the 
pricing of prescription pharmaceuticals is subject to governmental control and access. In these countries, pricing negotiations 
with  governmental  authorities  can  take  considerable  time  after  the  receipt  of  marketing  approval  for  a  product.  To  obtain 
reimbursement  or  pricing  approval  in  some  countries,  pharmaceutical  firms  may  be  required  to  conduct  a  clinical  trial  that 
compares the cost-effectiveness of the product to other available therapies. 

Approval of companion diagnostic devices 

In the European Union, medical devices such as companion diagnostics must comply with the General Safety and Performance 
Requirements,  or  SPRs,  detailed  in Annex  I  of  the  EU  Medical  Devices  Regulation  (Regulation  (EU)  2017/745),  or  MDR 
which  came  into  force  on  May  26,  2021  and  replaced  the  previously  applicable  EU  Medical  Devices  Directive  (Council 
Directive  93/42/EEC).  Compliance  with  SPRs  and  additional  requirements  applicable  to  companion  medical  devices  is  a 
prerequisite to be able to affix the CE Mark of Conformity to medical devices, without which they cannot be marketed or sold. 
To  demonstrate  compliance  with  the  SPRs,  a  manufacturer  must  undergo  a  conformity  assessment  procedure,  which  varies 
according  to  the  type  of  medical  device  and  its  classification.  The  MDR  is  meant  to  establish  a  uniform,  transparent, 
predictable, and sustainable regulatory framework across the European Union for medical devices. 

Separately, the regulatory authorities in the European Union also adopted a new In Vitro Diagnostic Regulation, or IVDR, (EU) 
2017/746,  which  became  effective  in  May  2022.  The  new  regulation  replaces  the  In  Vitro  Diagnostics  Directive  (IVDD) 
98/79/EC. Manufacturers wishing to apply to a notified body for a conformity assessment of their in vitro diagnostic medical 
device had until May 2022 to update their Technical Documentation to meet the requirements and comply with the new, more 
stringent Regulation. The regulation, among other things, strengthens the rules on placing devices on the market and reinforce 
surveillance once they are available; establishes explicit provisions on manufacturers’ responsibilities for the follow-up of the 
quality, performance, and safety of devices placed on the market; improves the traceability of medical devices throughout the 
supply chain to the end-user or patient through a unique identification number; sets up a central database to provide patients, 
healthcare  professionals  and  the  public  with  comprehensive  information  on  products  available  in  the  European  Union;  and 
strengthens rules for the assessment of  certain high-risk devices, such  as  implants, which may  have to undergo  an  additional 
check by experts before they are placed on the market. 

37 

 
General Data Protection Regulation 

Many countries outside of the United States maintain rigorous laws governing the privacy and security of personal information. 
The  collection,  use,  disclosure,  transfer,  or  other  processing  of  personal  data,  including  personal  health  data,  regarding 
individuals  who  are  located  in  the  EEA,  and  the  processing  of  personal  data  that  takes  place  in  the  EEA,  is  subject  to  the 
General Data Protection Regulation, or GDPR, which became effective on May 25, 2018. The GDPR is wide-ranging in scope 
and  imposes  numerous  requirements  on  companies  that  process  personal  data,  and  it  imposes  heightened  requirements  on 
companies that process health and other sensitive data, such as requiring in many situations that a company obtain the consent 
of the individuals to whom the sensitive personal data relate before processing such data. Examples of obligations imposed by 
the  GDPR  on  companies  processing  personal  data  that  fall  within  the  scope  of  the  GDPR  include  providing  information  to 
individuals regarding data processing activities, implementing safeguards to protect the security and confidentiality of personal 
data, appointing a data protection officer, providing notification of data breaches and taking certain measures when engaging 
third-party processors. 

The GDPR also imposes strict rules on the transfer of personal data to countries outside the EEA, including the United States, 
and permits data protection authorities to impose large penalties for violations of the GDPR, including potential fines of up to 
€20 million or 4% of annual global revenues, whichever  is  greater. The  GDPR  also  confers a private  right  of  action on data 
subjects  and  consumer  associations  to  lodge  complaints  with  supervisory  authorities,  seek  judicial  remedies,  and  obtain 
compensation for damages resulting from violations of the GDPR. Compliance with the GDPR is a rigorous and time-intensive 
process  that  may  increase  the  cost  of  doing  business  or  require  companies  to  change  their  business  practices  to  ensure  full 
compliance. In July 2020, the Court of Justice of the  European  Union,  or the  CJEU,  invalidated  the  EU-U.S.  Privacy Shield 
framework,  one  of  the  mechanisms  used  to  legitimize  the  transfer  of  personal  data  from  the  EEA  to  the  United  States.  The 
CJEU decision also drew into question the long-term viability of an alternative means of data transfer, the standard contractual 
clauses,  for  transfers  of  personal  data  from  the  EEA  to  the  United  States.  Following  the  withdrawal  of  the  United  Kingdom 
from the European Union, the U.K. Data Protection Act 2018 applies to the processing of personal data that takes place in the 
United Kingdom and includes parallel obligations to those set forth by GDPR. 

Additionally, in October 2022, President Biden signed an executive order to implement the EU-U.S. Data Privacy Framework, 
which would serve as a replacement to the EU-U.S. Privacy Shield. The European Commission initiated the process to adopt an 
adequacy decision for the EU-U.S. Data Privacy Framework in December 2022. It is unclear if and when the framework will be 
finalized  and  whether  it  will  be  challenged  in  court.  The  uncertainty  around  this  issue  may  further  impact  our  business 
operations in the European Union. 

Brexit and the regulatory framework in the United Kingdom 

The  United  Kingdom’s  withdrawal  from  the  European  Union  took  place  on  January  31,  2020. The  European  Union  and  the 
United Kingdom reached an agreement on their new partnership in the Trade and Cooperation Agreement, or the Agreement, 
which was applied provisionally beginning on January 1, 2021 and which became effective on May 1, 2021. The Agreement 
focuses  primarily  on  free  trade  by  ensuring  no  tariffs  or  quotas  on  trade  in  goods,  including  healthcare  products  such  as 
medicinal products. Thereafter, the European Union and the United Kingdom will form two separate markets governed by two 
distinct regulatory and legal regimes. As such, the Agreement seeks to minimize barriers to trade in goods while accepting that 
border checks will become inevitable as a consequence that the United Kingdom is no longer part of the single market. As of 
January 1, 2021, the Medicines and Healthcare products Regulatory Agency, or the MHRA, became responsible for supervising 
medicines  and  medical  devices  in  Great  Britain,  comprising  England,  Scotland  and  Wales  under  domestic  law  whereas 
Northern Ireland continues to be subject to EU rules under the Northern Ireland Protocol. The MHRA will rely on the Human 
Medicines Regulations 2012 (SI 2012/1916) (as amended), or the HMR, as the basis for regulating medicines. The HMR has 
incorporated into the domestic law the body of EU law instruments governing medicinal products that pre-existed prior to the 
United Kingdom’s withdrawal from the European Union. 

Since  a  significant  proportion  of  the  regulatory framework  for pharmaceutical  products  in  the  United  Kingdom  covering  the 
quality,  safety,  and  efficacy  of  pharmaceutical  products,  clinical  trials,  marketing  authorization,  commercial  sales,  and 
distribution of pharmaceutical products is derived from EU directives and regulations, Brexit may have a material impact upon 
the  regulatory  regime  with  respect  to  the  development,  manufacture,  importation,  approval  and  commercialization  of  our 
product  candidates  in  the  United  Kingdom.  For  example,  the  United  Kingdom  is  no  longer  covered  by  the  centralized 
procedures  for  obtaining  EU-wide  marketing  authorization  from  the  EMA,  and  a  separate  marketing  authorization  will  be 
required  to  market  our  product  candidates  in  the  United  Kingdom.  However,  until  December  31,  2023,  it  is  possible  for  the 
MHRA to rely on a decision taken by the European Commission and EMA’s CHMP on the approval of MAA or variations via 
the centralized procedure, or the so called “Reliance Procedure.” 

38 

 
Intellectual property 

We actively seek to protect the proprietary technology that we consider important to our business, including pursuing patents 
that  cover  our  ADC  platforms,  proprietary  compositions  of  matter,  ADC  product  candidates  and  methods  of  using  and 
manufacturing the same, as well as any other relevant inventions and improvements that are considered commercially important 
to  the  development  of  our  business.  We  also  rely  on  trade  secrets,  know-how  and  continuing  technological  innovation  to 
develop and maintain our proprietary and intellectual property position. 

Our commercial success will depend significantly on our ability to obtain and maintain patents and other proprietary protection 
for the technology, inventions and improvements we consider important to our business, and to defend our patents, preserve the 
confidentiality of our trade secrets and operate without infringing the patents and proprietary rights of third parties. Our policy 
is to seek to protect our proprietary and intellectual property position by, among other methods, filing U.S., international (under 
Patent  Cooperation  Treaty,  or  PCT)  and  foreign  patent  applications  related  to  our  proprietary  technology,  inventions  and 
improvements  that  we  consider  to  be  important  to  the  development  and  implementation  of  our  business.  We  also  believe  in 
protecting our unpatented trade secrets and know-how and continuing our technological innovation to develop our business and 
to maintain our competitive position. 

The  term  of  individual  patents  depends  upon  the  legal  term  for  patents  in  the  countries  in  which  they  are  obtained. In  most 
countries,  including  the  United  States,  the  patent  term  is  20  years  from  the  earliest  filing  date  of  a  non-provisional  patent 
application. In the United States, a patent’s term may be lengthened by patent term adjustment, which compensates a patentee 
for  administrative  delays  by  the  USPTO  in  examining  and  granting  a  patent  or  may  be  shortened  if  a  patent  is  terminally 
disclaimed over an earlier filed patent. The term of a patent that covers a drug or biological product may also be eligible for 
patent term extension when FDA approval is granted, provided statutory and regulatory requirements are met. In the future, if 
and when our drug candidates receive approval by the FDA or foreign regulatory authorities, we expect to apply for patent term 
extensions  on  issued  patents  covering  those  drugs,  depending  upon  the  length  of  the  clinical  trials  for  each  drug  and  other 
factors. There can be no assurance that any of our pending patent applications will issue or that we will benefit from any patent 
term extension or favorable adjustments to the terms of any of our patents. 

As with other biotechnology and pharmaceutical companies, our ability to maintain and solidify our proprietary and intellectual 
property position for our drug candidates and technologies will depend on our success in obtaining effective patent claims and 
enforcing  those  claims  if  granted.  However,  our  pending  patent  applications,  and  any  patent  applications  that  we  may  in  the 
future file or license from third parties, may not result in the issuance of patents. We also cannot predict the breadth of claims 
that may be allowed or enforced in our patents. Any issued patents that we may currently own or license or may receive in the 
future may be challenged, invalidated, circumvented  or have the  scope of  their  claims narrowed. For  example,  we  cannot  be 
certain of the priority of inventions covered by pending third party patent applications. If third parties prepare and file patent 
applications in the United States that also claim technology or therapeutics to which we have rights, we may have to participate 
in interference proceedings in the USPTO to determine priority of invention, which could result in substantial costs to us, even 
if the eventual outcome is favorable to us, which is highly unpredictable. In addition, because of the extensive time required for 
clinical  development  and  regulatory  review  of  a  drug  candidate  we  may  develop,  it  is  possible  that,  before  any  of  our  drug 
candidates  can  be  commercialized,  any  related  patent  may  expire  or  remain  in  force  for  only  a  short  period  following 
commercialization,  thereby  limiting  the  protection  such  patent  would  afford  the  respective  product  and  any  competitive 
advantage  such  patent  may  provide.  For  more  information  regarding  the  risks  related  to  our  intellectual  property,  please  see 
“Risk factors—Risks related to our intellectual property.” 

As of December 31, 2022, we owned, in all of our patent portfolios, 24 issued U.S. patents, 18 pending non-provisional U.S. 
patent applications (including  two allowed U.S. patent applications),  seven  pending  provisional  U.S.  patent applications,  131 
issued  foreign  patents,  three  pending  PCT  patent  applications  and  209  pending  foreign  patent  applications  (including  three 
allowed  foreign  patent  applications),  in  a  number  of  foreign  jurisdictions,  including,  but  not  limited  to, Algeria,  Argentina, 
Australia,  Brazil,  Canada,  Chile,  China,  Colombia,  Europe,  Eurasia,  Egypt,  Gulf  Cooperation  Council,  Hong  Kong,  India, 
Indonesia,  Israel,  Japan,  Mexico,  Macau,  Malaysia,  Nigeria,  Pakistan,  New  Zealand,  Philippines,  Russia,  Saudi  Arabia, 
Singapore,  South  Korea,  South  Africa,  Taiwan,  Thailand,  United  Arab  Emirates  and  Vietnam.  Our  10  issued  U.S.  patents 
covering our Fleximer ADC platform are projected to expire in 2032, excluding any additional term for patent term adjustments 
or patent term extensions; our two issued U.S. patents covering our Dolaflexin ADC platform are projected to expire in 2034 
and  2038,  excluding  any  additional  term  for  patent  term  adjustments  or  patent  term  extensions;  our  two  issued  U.S.  patents 
covering UpRi are projected to expire in 2037 and 2039, excluding any additional term for patent term adjustments or patent 
term extensions; our one issued U.S. patent covering our Dolasynthen ADC platform is projected to expire in 2037, excluding 
any  additional  term  for  patent  term  adjustments  or  patent  term  extensions;  our  three  issued  U.S.  patents  covering  our  novel 
HER2  antibody  are  projected  to  expire  in  2035,  excluding  any  additional  term  for  patent  term  adjustments  or  patent  term 

39 

 
 
 
 
extensions;  our  one  issued  U.S.  patent  covering  our  STING  agonist  payload  is  projected  to  expire  in  2040,  excluding  any 
additional term for patent term adjustments or patent term extensions; our additional five issued U.S. patents are projected to 
expire between 2033 and 2037, excluding any additional term for patent term adjustments or patent term extensions; and any 
patent  that  may  issue  from  our  pending  U.S.  applications  are  projected  to  expire  between  2032  and  2043,  in  each  case, 
excluding  any  additional  term  for  patent  term  adjustments  or  patent  term  extensions.  In  addition,  we  have  exclusively  in-
licensed  four  issued  U.S.  patents  and  one  issued  European  patent  for  the  NaPi2b  antibody  from  Recepta,  which  Recepta 
licensed from the Ludwig Institute for Cancer Research. These in-licensed issued U.S. and European patents are projected to 
expire  in  2029,  excluding  any  additional  term for  patent  term  adjustments  or  patent  term  extensions.  Recepta  still  owns  one 
pending Brazilian patent application for the NaPi2b antibody, which is not licensed to us. A patent issuing from this Brazilian 
patent  application  is  projected  to  expire  in  2029,  excluding  any  additional  term  for  patent  term  adjustments  or  patent  term 
extensions. We have also non-exclusively in-licensed from Synaffix certain patents and patent applications for their proprietary 
site-specific  conjugation  technology.  These  in-licensed  Synaffix  patents  and  patent  applications  are  eight  issued  US  patents, 
three  pending  non-provisional  U.S.  patent  applications,  thirteen  issued  foreign  patents,  and  14  pending  foreign  patent 
applications, in a number of foreign jurisdictions, including, but not limited to, China, Europe, India, Japan, and Netherlands 
These in-licensed issued U.S. and European patents are projected to expire from 2031 to 2040, excluding any additional term 
for patent term adjustments or patent term extensions. We have so far not filed for patent protection in all national and regional 
jurisdictions  where  such  protection  may  be  available.  In  addition,  we  may  decide  to  abandon  national  and  regional  patent 
applications  before  they  are  granted.  Finally,  the  grant  proceeding  of  each  national  or  regional  patent  is  an  independent 
proceeding  which  may  lead  to  situations  in  which  applications  might  in  some  jurisdictions  be  refused  by  the  relevant 
registration authorities, while granted by others. It is also quite common that depending on the country, various scopes of patent 
protection may be granted on the same product candidate or technology. 

The intellectual property portfolio of our ADC platforms, our ADC product candidates and components thereof, and companion 
or complementary diagnostics are summarized below. Some of these portfolios are in very early stages, and prosecution has yet 
to  commence  on  some  of  the  pending  patent  applications.  Prosecution  is  a  lengthy  process,  during  which  the  scope  of  the 
claims initially submitted for examination by the USPTO may be narrowed (sometimes significantly) by the time they issue, if 
they issue at all. We expect this to be the case with respect to our pending patent applications referred to below. 

Fleximer ADC platform 

The intellectual property portfolio for our Fleximer ADC platform is directed to compositions of matter for the Fleximer ADCs, 
as well as methods of using and making these novel conjugates, compositions of matter for Fleximer drug conjugates prior to 
conjugation  with  the  antibody  or  antibody  fragment  and  methods  of  making  the  same,  and  compositions  of  matter  for  our 
proprietary auristatin DolaLock compounds and conjugates thereof (e.g., to Fleximer and/or an antibody or antibody fragment). 
As of December 31, 2022, we owned 10 issued U.S. patents, one pending non-provisional  U.S.  patent application, 50  issued 
foreign patents and two pending foreign patent applications, in a number of foreign jurisdictions, including, but not limited to, 
Australia, Brazil, Canada, China, Europe, Hong Kong, Israel, India, Japan, Macau, Mexico, Russia, South Korea, and Taiwan. 
Any U.S. or foreign patent issuing from the pending applications covering the Fleximer ADC platform is projected to expire in 
2032, excluding any additional term for patent term adjustments or patent term extensions. 

Dolaflexin ADC platform 

The  intellectual  property  portfolio  for  our  Dolaflexin ADC  platform  is  directed  to  compositions  of  matter  for  the  Dolaflexin 
ADCs, as well as methods of using and making these novel conjugates, compositions of matter for Dolaflexin drug conjugates 
prior to conjugation with the antibody or antibody fragment and methods of making the same. As of December 31, 2022, we 
owned two issued U.S. patents, 36 issued foreign patents, and nine pending foreign patent applications, in a number of foreign 
jurisdictions, including, but not limited to, Australia, Brazil, Canada, China, Eurasia, Europe, Hong Kong, Israel, India, Japan, 
South  Korea,  Mexico,  South Africa  and  Taiwan. Any  U.S.  or  foreign  patent  issuing  from  the  pending  applications  covering 
Dolaflexin ADC platform is  projected to expire in 2034, excluding any additional term for patent term adjustments or patent 
term  extensions,  and  any  U.S.  or  foreign  patent  issuing  from  the  pending  applications  covering  the  method  of  making  the 
Dolaflexin  ADC  is  projected  to  expire  in  2038,  excluding  any  additional  term  for  patent  term  adjustments  or  patent  term 
extensions. 

UpRi ADC 

The intellectual property portfolio for UpRi, our leading NaPi2b ADC product candidate is directed to compositions of matter 
for our novel ADC based on exclusively in-licensed NaPi2b antibody and our Dolaflexin platform, as well as methods of using 
and making these novel conjugates, methods of administration and companion or complementary diagnostics. As of December 
31, 2022, we owned two issued U.S. patents, five pending non-provisional U.S. patent applications (including one allowed U.S. 
patent  application),  two  pending  provisional  U.S.  patent  applications,  five  issued  foreign  patents,  52  pending  foreign  patent 
applications (including two allowed foreign patent applications), in a number of foreign jurisdictions, including, but not limited 

40 

 
 
 
 
 
 
 
 
to, Argentina, Australia, Brazil, Canada, China, Eurasia, Europe, Japan, Gulf Cooperation Council, Israel, India, Mexico, New 
Zealand, Pakistan, South Africa, South Korea, Macau, Hong Kong, Taiwan, and two pending PCT applications directed to the 
composition of matter for UpRi, methods of using and making same, companion or complementary diagnostics for the UpRi 
ADC and UpRi dosing regimens. We also intend to enter the national/regional phase of the pending PCT patent applications in 
foreign jurisdictions, including, but not limited to, Australia, Brazil, Canada, China, Eurasia, Europe, Hong Kong, Israel, India, 
Japan, Saudi Arabia, Singapore, South Korea, Macau, Mexico, New Zealand, South Africa and United Arab Emirates. Any U.S. 
or  foreign patent issuing from the pending applications  covering  the  composition  of  matter of UpRi  is projected to expire  in 
2037,  excluding  any  additional  term  for  patent  term  adjustments  or  patent  term  extensions,  and  any  U.S.  or  foreign  patent 
issuing from the pending applications covering UpRi companion or complementary diagnostics is projected to expire in 2038, 
excluding  any  additional  term  for  patent  term  adjustments  or  patent  term  extensions,  and  any  U.S.  or  foreign  patent  issuing 
from the pending applications covering the UpRi dosing regimens is projected to expire in 2039, 2042, and 2043, excluding any 
additional term for patent term adjustments or patent term extensions. 

In addition, as mentioned above, we have exclusively in-licensed four issued U.S. patents and one issued European patent for 
the  novel  NaPi2b  antibody  from  Recepta,  which  Recepta  licensed  from  the  Ludwig Institute  for  Cancer  Research. These  in-
licensed  issued  U.S.  and  European  patents  are  projected  to  expire  in  2029,  excluding  any  additional  term  for  patent  term 
adjustments  or  patent  term  extensions.  Recepta  still  owns  one  pending  Brazilian  patent  application  for  the  NaPi2b  antibody, 
which is not licensed to us. A patent issuing from this Brazilian patent application is projected to expire in 2029, excluding any 
additional term for patent term adjustments or patent term extensions. 

Dolasynthen ADC platform 

The  intellectual  property  portfolio  for  our  novel  Dolasynthen  platform  is  directed  to  compositions  of  matter  for  the  novel 
scaffold and ADCs thereof, as well as methods of using and making these novel conjugates and scaffolds. As of December 31, 
2022, we owned one issued U.S. patent, three pending non-provisional U.S. patent applications and 51 pending foreign patent 
applications,  in  a  number  of  foreign  jurisdictions,  including,  but  not  limited  to, Argentina, Australia,  Brazil,  Canada,  China, 
Eurasia,  Europe,  Hong  Kong,  Israel,  India,  Japan,  Mexico,  New  Zealand,  Pakistan,  Saudi Arabia,  Singapore,  South  Korea, 
Taiwan,  and  United  Arab  Emirates.  Any  U.S.  or  foreign  patent  issuing  from  the  pending  applications  covering  the  novel 
Dolasynthen platform is projected to expire between 2037 and 2041, excluding any additional term for patent term adjustments 
or patent term extensions. 

XMT-1660 ADC  

The intellectual property portfolio for XMT-1660, our site-specific B7-H4 ADC product candidate is directed to compositions 
of matter for our novel ADC based on our novel B7-H4 antibody and our Dolasynthen platform, as well as methods of using, 
making these novel conjugates and administration of these novel conjugates. As of December 31, 2022, we owned one pending 
non-provisional  U.S.  patent  application,  two  pending  provisional  applications,  three  pending  foreign  patent  applications  in  a 
number  of  foreign  jurisdictions  including,  but  not  limited  to,  Taiwan, Argentina,  and  Pakistan,  and  one  pending  PCT  patent 
application. We intend to enter the national/regional phase of the PCT patent application in a number of foreign jurisdictions, 
including,  but  not  limited  to,  Australia,  Brazil,  Canada,  China,  Eurasia,  Europe,  Hong  Kong,  Israel,  India,  Japan,  Macau, 
Mexico, South Korea, New Zealand, Singapore, South Africa,  Saudi Arabia, and  United Arab Emirates. Any U.S.  or  foreign 
patent  issuing  from  the  pending  applications  covering  XMT-1660  is  projected  to  expire  in  2042  and  2043,  excluding  any 
additional term for patent term adjustments or patent term extensions. 

Immunosynthen ADC platform  

The intellectual property portfolio for our novel Immunosynthen platform is directed to compositions of matter for the novel 
STING agonists and ADCs thereof, as well as methods of using and methods of making these novel payloads and ADCs. As of 
December  31,  2022,  we  owned  one  issued  U.S.  patent,  one  pending  non-provisional  U.S.  patent  applications,  19  pending 
foreign  patent  applications  in  a  number  of  foreign  jurisdictions,  including,  but  not  limited  to,  Argentina,  Australia,  Brazil, 
Canada,  China,  Eurasia,  Europe,  Hong  Kong,  Israel,  India,  Japan,  Mexico,  New  Zealand,  Saudi Arabia,  South  Korea,  South 
Africa, Taiwan and United Arab Emirates related to our novel STING agonists, and two pending non-provisional U.S. patent 
applications  and  29  pending  foreign  patent  applications  in  a  number  of  foreign  jurisdictions,  including,  but  not  limited  to, 
Algeria, Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Europe, Eurasia, Egypt, India, Indonesia, Israel, Japan, 
Mexico, Malaysia, Nigeria, Pakistan, New Zealand, Philippines, Saudi Arabia, Singapore, South Korea, South Africa, Taiwan, 
Thailand, United Arab Emirates and Vietnam, related to our Immunosynthen platform. Any U.S. or foreign patent issuing from 
the pending applications covering the novel STING agonists is projected to expire in 2040, excluding any additional term for 
patent  term  adjustments  or  patent  term  extensions,  and  any  U.S.  or  foreign  patent  issuing  from  the  pending  applications 
covering the Immunosynthen platform is projected to expire in 2041, excluding any additional term for patent term adjustments 
or patent term extensions. 

41 

 
 
 
 
 
 
 
 
 
XMT-2056 ADC  

The  intellectual  property  portfolio  for  XMT-2056,  our  HER2-targeted  novel  Immunosynthen  ADC,  is  directed  to  the 
compositions of matter for our novel ADC based on  our novel  HER2  antibody and  our Immunosynthen platform,  as well as 
methods of using, making these novel conjugates, combination comprising XMT-2056 and administration of XMT-2056. As of 
December  31,  2022,  we  owned  one  pending  non-provisional  U.S.  patent  application,  three  pending  provisional  U.S.  patent 
applications  and  23  pending  foreign  patent  applications  in  a  number  of  foreign  jurisdictions,  including,  but  not  limited  to, 
Argentina,  Australia,  Brazil,  Chile,  Colombia,  Europe,  Eurasia,  Egypt,  India,  Indonesia,  Israel,  Japan,  Mexico,  Malaysia, 
Nigeria, Pakistan, New Zealand, Philippines, Saudi Arabia, South Korea, South Africa, Taiwan and United Arab Emirates. Any 
U.S. or foreign patent issuing from the pending applications covering the composition of matter of XMT-2056 is projected to 
expire in 2041, excluding any additional term for patent term adjustments or patent term extensions, any U.S. or foreign patent 
issuing from the pending applications covering combinations comprising XMT-2056 is projected to expire in 2043, excluding 
any  additional  term  for  patent  term  adjustments  or  patent  term  extensions,  and  any  U.S.  or  foreign  patent  issuing  from  the 
pending applications covering the XMT-2056 dosing regimens is projected to expire in 2043, excluding any additional term for 
patent term adjustments or patent term extensions. 

In addition to the above with respect to XMT-2056, as of December 31, 2022, we owned three issued U.S. patents, one pending 
non-provisional U.S. patent application, 19 issued foreign patents and seven pending foreign patent applications (including one 
allowed  foreign  patent  application),  in  a  number  of  foreign  jurisdictions,  including,  but  not  limited  to, Argentina, Australia, 
Brazil,  Canada,  China,  Eurasia,  Europe,  Hong  Kong,  Israel,  India,  Japan,  Macau,  Mexico,  South  Korea,  New  Zealand  and 
Taiwan, directed to the novel HER2 antibody. Any U.S. or foreign patent issuing from the pending applications covering the 
novel HER2 antibody is projected to expire in 2035, excluding any additional term for patent term adjustments or patent term 
extensions. 

In addition to patents, we rely upon unpatented trade secrets and know-how and continuing technological innovation to develop 
and maintain our competitive position. We seek to protect our proprietary information, in part, by executing confidentiality and 
assignment of inventions agreements with our employees and consultants, which agreements may also include appropriate non-
competition  and  non-solicit  agreements  depending  on  level  and  role,  as  well  as  confidentiality  agreements  with  our 
collaborators  and  scientific  advisors.  We  have  also  executed  agreements  requiring  assignment  of  inventions  with  selected 
scientific  advisors  and  collaborators.  The  confidentiality  agreements  we  enter  into  are  designed  to  protect  our  proprietary 
information  and  the  agreements  or  clauses  requiring  assignment  of  inventions  to  us  are  designed  to  grant  us  ownership  of 
technologies that are developed through our relationship with the respective counterparty. We cannot guarantee, however, that 
we will have executed such agreements with all applicable employees and contractors, or that these agreements will afford us 
adequate protection of our intellectual property and proprietary information rights. Trade secrets and know-how can be difficult 
to protect. In particular, we anticipate that with respect to our technology platforms, trade secrets and know-how will over time 
be  disseminated  within  the  industry  through  independent  development  and  public  presentations  describing  the  methodology. 
For  more  information  regarding  the  risks  associated  with  our  trade  secrets,  please  see  “Risk  factors—Risks  related  to  our 
intellectual property—Confidentiality agreements with employees and third parties may not prevent unauthorized disclosure of 
trade secrets and other proprietary information.” 

Competition 

The  biotechnology  and  biopharmaceutical  industries,  and  the  oncology  subsector,  are  characterized  by  rapid  evolution  of 
technologies,  fierce  competition  and  strong  defense  of  intellectual  property.  Any  product  candidates  that  we  successfully 
develop and commercialize will have to compete with existing therapies and new therapies that may become available in the 
future. While we believe that our proprietary ADC platforms and scientific expertise provide us with competitive advantages, a 
wide  variety  of  institutions,  including  large  biopharmaceutical  companies,  specialty  biotechnology  companies,  academic 
research departments and public and private research institutions, are actively developing potentially competitive products and 
technologies. These competitors generally fall within the following categories: 

New cancer treatments: Many global pharmaceutical companies, as well as medium and small biotechnology companies, are 
pursuing  new  cancer  treatments  whether  small  molecules,  biologics  or  ADCs.  Any  of  these  treatments  could  prove  to  be 
superior clinically to our products. 

ADC  platforms:  Although  Dolaflexin,  Dolasynthen,  Immunosynthen  and  certain  initiatives  we  have  underway  are  highly 
differentiated  and  proprietary,  many  companies  continue  to  invest  in  innovation  in  the  ADC  field  including  new  payload 
classes,  new  conjugation  approaches  and  new  targeting  moieties. Any  of  these  initiatives  could  lead  to  a  platform  that  has 
superior properties to ours. We are also aware of multiple  companies with ADC technologies that may be competitive to our 
platforms, including Daiichi Sankyo Company, Limited; ImmunoGen, Inc.; Gilead Sciences, Inc.; Pfizer Inc.; and Seagen Inc. 
These companies or their partners and collaborators, including Astellas Pharma Inc.; AstraZeneca plc; AbbVie Inc.; Genentech, 

42 

 
 
 
 
 
a member of the Roche Group; and Takeda, may develop product candidates that compete in the same indications as our current 
and  future  product  candidates.  Multiple  companies  are  also  developing ADCs  that  could  compete  with  our  Immunosynthen 
product candidates, including Bolt Biotherapeutics, Inc. and Takeda, albeit with differing immune stimulating approaches. We 
expect to compete based on our innovative technology and the efficacy, safety and tolerability profile of our ADCs compared to 
other  product  candidates,  but  if  our ADCs  are  not  demonstrably  superior  in  these  respects,  we  may  not  be  able  to  compete 
effectively. 

Ovarian cancer: The first indication that we are targeting for UpRi, our most advanced clinical candidate, is ovarian cancer. 
There are multiple therapies currently available to treat both newly diagnosed and relapsed ovarian cancer, including platinum 
agents,  non-platinum  chemotherapy,  PARP  inhibitors,  bevacizumab  and  mirvetuximab  soravtansine.  In  addition,  multiple 
investigational product candidates are in development to treat these ovarian cancer patients, including MORAb-202 (Eisai Co., 
Ltd.  and  BMS)  and  STRO-002  (Sutro  Biopharma,  Inc.),  which  are  investigational  ADCs.  There  are  also  ongoing  Phase  3 
clinical trials of agents and treatment modalities including Tumor Treating Fields (Novocure GmbH) and AVB-500 (Aravive, 
Inc.),  which,  if  successful,  could  alter  the  treatment  landscape  for  platinum  resistant  ovarian  cancer.  Our  ability  to  compete 
effectively with these and other emerging ovarian cancer treatments will depend on our ability to differentiate UpRi from these 
other therapies based on target patient selection, efficacy and tolerability. If we are unable to effectively differentiate UpRi, this 
will negatively impact our ability to compete in ovarian cancer. 

Breast Cancer: We are planning to evaluate two of our product candidates currently in clinical development, XMT-2056 and 
XMT-1660, in patients with breast cancer indications. Multiple therapies are currently available to treat metastatic breast cancer 
across newly diagnosed and relapsed settings, including but not limited to aromatase inhibitors, CDK 4/6 inhibitors, HER2-
targeted therapies, anti-PD-1 inhibitors, PI3K inhibitors and ADCs targeting HER2 and Trop-2. Additional classes of therapies 
currently in development include oral selective estrogen receptor degraders (known as SERDs), Akt inhibitors, and ADCs, 
among others. The metastatic breast cancer treatment paradigm is evolving with the introduction of a newly defined subset of 
HER2-low breast cancer, following the FDA approval of trastuzumab deruxtecan. Our ability to compete effectively in the 
breast cancer market will depend on evolving standards of care across patient subsets (based on HER2 and hormone receptor 
status), and our ability to differentiate XMT-2056 and XMT-1660 from other available therapies based on efficacy and 
tolerability.  

Many  of  our  competitors,  either  alone  or  with  strategic  partners,  have  substantially  greater  financial,  technical  and  human 
resources than we do. Accordingly, our competitors may be more successful than us in obtaining approval for treatments and 
achieving  widespread  market  acceptance,  rendering  our  treatments  obsolete  or  non-competitive.  Accelerated  merger  and 
acquisition  activity  in  the  biotechnology  and  biopharmaceutical  industries  may  result  in  even  more  resources  being 
concentrated among a smaller number of our competitors. These  companies  also compete  with  us in recruiting and retaining 
qualified  scientific  and  management  personnel,  establishing  clinical  trial  sites  and  patient  enrollment  for  clinical  trials  and 
acquiring technologies complementary to, or necessary for, our programs. Smaller or early-stage companies may also prove to 
be  significant  competitors,  particularly  through  collaborative  arrangements  with  large  and  established  companies.  Our 
commercial opportunity could be substantially limited  in the event that our competitors  develop  and commercialize products 
that are more effective, safer, more convenient or less expensive than our comparable products. In geographies that are critical 
to our commercial success, competitors may also obtain regulatory approvals before us, resulting in our competitors building a 
strong market position in advance of our products’ entry. We believe the factors determining the success of our programs will be 
the efficacy, safety and tolerability of our product candidates. 

Employees and Human Capital 

As  of  December  31,  2022,  we  had  228 full  time  employees,  including  151  with  M.D.,  Ph.D.  or  other  advanced  degrees.  Of 
these  employees,  171  are  engaged  in  research  and  development  and  57  are  engaged  in  general  and  administrative  activities. 
None  of  our  employees  are  represented  by  a  labor  union  or  covered  by  a  collective  bargaining  agreement.  We  consider  our 
relationship with our employees to be good. 

We believe  that our future success largely  depends  upon our continued  ability  to  attract and retain  highly skilled  employees. 
Our human capital objectives include, as applicable, identifying, recruiting, retaining, incentivizing and integrating our existing 
and  additional  employees,  and  focusing  on  employee  well-being  and  workplace  safety.  We  provide  our  employees  with 
competitive salaries and bonuses, opportunity for equity ownership, development programs that enable continued learning and 
growth,  and  a  robust  employment  package  that  promotes  wellness  across  all  aspects  of  their  lives,  including  healthcare, 
retirement planning, and paid time off.  

We also believe that fostering diversity, equity, and inclusion is a key element to discovering, developing and bringing therapies 
to  patients  with  cancer. As  of  December  31,  2022,  57%  of  our  global  workforce  identified  as  female.  We  strive  to  build  a 

43 

 
 
 
 
 
 
workforce  representative  of  the  communities  and  patients  we  serve  and  to  nurture  an  inclusive  culture  where  all  voices  are 
welcomed, heard, and respected. 

Facilities 

Our  corporate  headquarters  are  located  in  Cambridge,  Massachusetts. We  occupy  approximately  45,000  square  feet  of  office 
and laboratory space that we lease in the multi-tenant building in which our corporate headquarters are located. The lease for 
the substantial majority of this space expires in March 2026. We have an option to extend the lease term for an additional five 
years  thereafter.  We  believe  that  this  office  and  laboratory  space  is  sufficient  to  meet  our  current  needs  and  that  suitable 
additional space will be available as and when needed. 

Corporate Information 

We were incorporated in 2001 as a Delaware corporation. Our principal executive offices are located at 840 Memorial Drive, 
Cambridge, MA 02139, and our telephone number is 617-498-0020. Our internet site is www.mersana.com. We routinely make 
available important information free of  charge,  including copies  of  our Annual Reports on  Form 10-K,  Quarterly  Reports on 
Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) 
of the Exchange Act, as soon as reasonably practicable after such reports are electronically filed with, or furnished to, the SEC. 
We recognize our website as a key channel of distribution to reach public investors and as a means of disclosing material non-
public information to comply with our disclosure obligations under SEC Regulation FD. Information contained on our website 
shall not be deemed incorporated into, or to be part of this Annual Report on Form 10-K, and any website references are not 
intended to be made through active hyperlinks. 

ITEM 1A. 

RISK FACTORS 

Our  operations  and  financial  results  are  subject  to  various  risks  and  uncertainties,  including  those  described  below.  The 
following  information  about  these  risks  and  uncertainties,  together  with  the  other  information  appearing  elsewhere  in  this 
Annual Report on Form 10-K, including our consolidated  financial  statements and  related  notes thereto, should be  carefully 
considered before making any decision to invest in our common stock. The risks and uncertainties described below are not the 
only ones we face. Additional risks and uncertainties not presently known to us or that we currently believe to be immaterial 
may also adversely affect our business or cause our actual results to differ materially from those contained in forward-looking 
statements  we  have  made  in  this  report  and  those  we  may  make  from  time  to  time.  If  any  of  the  following  risks  occur,  our 
business, financial condition, results of operations and future growth prospects could be materially and adversely affected. We 
cannot provide assurance that any of the events discussed below will not occur. 

Risks Related to Development and Approval of Our ADC Product Candidates 

Failure  of  a  discovery  program  or  product  candidate  may  occur  at  any  stage  of  preclinical  or  clinical  development,  and, 
because  our  and  our  collaborators'  discovery  programs  and  our  product  candidates  are  in  early  stages  of  preclinical  or 
clinical  development,  there  is  a  high  risk  of  failure.  We  or  our  collaborators  may  never  succeed  in  obtaining  regulatory 
approval and generating revenue from such discovery programs or product candidates. 

The early clinical results for our lead product candidate, upifitamab rilsodotin, or UpRi, the results from our preclinical studies 
of  XMT-1660  and  XMT-2056  and  the  early  results  from  preclinical  studies  or  clinical  trials  of  any  other  current  or  future 
product  candidates  are  not  necessarily  predictive  of  the  results  from  our  ongoing  or  future  discovery  programs,  preclinical 
studies or clinical trials. Promising results in preclinical studies and early encouraging clinical results of a drug candidate may 
not be predictive of similar results in later-stage preclinical studies or in humans during clinical trials. Many companies in the 
pharmaceutical and biotechnology industries have suffered significant setbacks in clinical trials after achieving positive results 
in  earlier  stages  of  clinical  development,  and  we  cannot  be  certain  that  we  will  not  face  similar  setbacks. These  companies’ 
setbacks have been caused by, among other things, preclinical findings made while clinical trials were underway or safety or 
efficacy events in preclinical or clinical trials, including previously unreported adverse events. Similarly, the design of a clinical 
trial  can  determine  whether  its  results  will  support  approval  of  a product,  and  flaws  in  the  design  of  a  clinical  trial may  not 
become apparent until the clinical trial is well advanced. 

Any clinical trials that we may conduct may not demonstrate the efficacy and safety necessary to obtain regulatory approval to 
market our product candidates. In addition, clinical trial results for one of our product candidates, or for competitor products 
utilizing similar technology, may raise concerns about the safety or efficacy of other product candidates in our pipeline. If the 
results of our ongoing or future clinical trials are inconclusive with respect to the efficacy of our product candidates, if we do 
not meet the clinical endpoints with statistical significance or if there are safety concerns or adverse events associated with our 

44 

 
 
product  candidates,  we  may  be  prevented  from  or  delayed  in  obtaining  marketing  approval  for  our  product  candidates.  For 
example, patients in our ongoing clinical trials of UpRi have experienced serious adverse events, or SAEs, including, without 
limitation, death, pneumonitis, renal impairment, abdominal pain, fatigue, vomiting, sepsis and pyrexia. We expect that certain 
patients in our ongoing clinical trials of UpRi, XMT-1660 and XMT-2056 and in future clinical trials will experience additional 
SAEs, including those that may result in death, as our product candidates progress through clinical development. 

There can be significant variability in safety or efficacy results between different clinical trials of the same product candidate 
due  to  numerous  factors,  including  changes  in  trial  procedures  set  forth  in  protocols,  differences  in  the  size  and  type  of  the 
patient populations, changes in and adherence to the dosing regimen and other clinical trial protocols and the rate of dropout 
among  clinical  trial  participants.  Moreover,  preclinical  and  clinical  data  are  often  susceptible  to  varying  interpretations  and 
analyses, and many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical 
trials have nonetheless failed to obtain U.S. Food and Drug Administration, or FDA, approval. Even if we or our collaborators 
believe that the results of clinical trials of our product candidates warrant marketing approval, the FDA or comparable foreign 
regulatory authorities may disagree and may not grant marketing approval of our product candidates. 

Alternatively, even if we obtain regulatory approval, that approval may be for indications or patient populations that are not as 
broad as intended or desired or may require labeling that includes significant use or distribution restrictions or safety warnings. 
We may also be required to perform additional or unanticipated clinical trials to obtain approval or be subject to additional post-
marketing testing requirements to maintain regulatory approval. In addition, regulatory authorities may withdraw their approval 
of a product or impose restrictions on its distribution, such as in the form of a risk evaluation and mitigation strategy, or REMS, 
program. The failure to obtain timely regulatory approval of product candidates, any product marketing limitations or a product 
withdrawal would negatively impact our business, results of operations and financial condition. 

Preliminary, interim and top-line data from our clinical trials that we announce or publish from time to time may change as 
more  patient  data  become  available  and  are  subject  to  audit  and  verification  procedures  that  could  result  in  material 
changes in the final data. 

From  time  to  time,  we  may  announce  or  publish  preliminary,  interim  or  top-line  data  from  our  clinical  trials.  Positive 
preliminary data may not be predictive of such trial’s subsequent or overall results. Interim data from clinical trials that we may 
complete  do  not  necessarily  predict  final  results  and  are  subject  to  the  risk  that  one  or  more  of  the  clinical  outcomes  may 
materially  change  as  patient  enrollment  continues  and  more  patient  data  become  available.  For  example,  we  have  reported 
interim  data  from  our  ongoing  Phase  1b/2  clinical  trial  of  UpRi,  but  we  have  not  yet  reported  final  data  from  the  trial. 
Preliminary  or  top-line  data  also  remain  subject  to  audit  and  verification  procedures  that  may  result  in  the  final  data  being 
materially  different  from  the preliminary  or  top-line  data we  may publish. As  a  result,  preliminary,  interim  and  top-line  data 
should be viewed with caution until the final data are available. Adverse differences between preliminary or interim data and 
final data could significantly harm our business prospects. 

We are currently evaluating a limited number of ADC product candidates in clinical trials. A failure of any of our product 
candidates in clinical development would adversely affect  our  business  and  may require  us  to discontinue  development of 
other ADC product candidates based on the same technology. 

UpRi,  XMT-1660  and  XMT-2056  are  currently  our  only  product  candidates  in  clinical  trials.  While  we  have  certain  other 
preclinical programs in development, it will take additional investment and time, and regulatory clearance, for such programs to 
reach the clinical stage of development. In addition, we have other product candidates in our current pipeline that are based on 
the  same  platforms  as  UpRi,  XMT-1660  and  XMT-2056.  If  a  product  candidate  fails  in  development  as  a  result  of  any 
underlying problem with our platforms, then we may be required to discontinue development of the product candidates that are 
based on the same technologies. If we were required to discontinue development of UpRi, XMT-1660 or XMT-2056 or of any 
other current or future product candidate, or if UpRi, XMT-1660 or XMT-2056 or any other current or future product candidate 
were to fail to receive regulatory approval or were to fail to achieve sufficient market acceptance, we could be prevented from 
or significantly delayed in achieving profitability. 

Events  that  may  delay  or  prevent  successful  commencement,  enrollment  or  completion  of  clinical  trials  of  our  product 
candidates could result in increased costs to us as well as a delay in obtaining, or failure to obtain, regulatory approval, or 
cause us to suspend or terminate a clinical trial, which could prevent us from commercializing our product candidates on a 
timely basis, or at all. 

45 

 
We  cannot  guarantee  that  clinical  trials,  including  our  ongoing  and  any  future  additional  clinical  trials  of  UpRi,  XMT-1660, 
XMT-2056 or any of our other current or future product candidates, will be conducted as planned or completed on schedule, if 
at all. A failure of one or more clinical trials can occur at any stage of testing, and other events may cause us to temporarily or 
permanently cease a clinical trial. Events that may prevent successful or timely commencement, enrollment or completion of 
clinical development include, among others: 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

delays in reaching a consensus with regulatory agencies on trial design; 

delays in reaching, or failing to reach, agreement on acceptable terms with prospective clinical research organizations, 
or CROs, site management organizations, or SMOs, and clinical trial sites; 

difficulties in obtaining required Institutional Review Board, or IRB, or Ethics Committee, or EC, approval at each 
clinical trial site; 

challenges in recruiting and enrolling suitable patients to participate in clinical trials that meet the criteria of the 
protocol for the clinical trial; 

imposition of a clinical hold by regulatory agencies, IRBs or ECs for any reason, including safety concerns or after an 
inspection of clinical operations or trial sites; 

delays in necessary screenings caused by third parties with which we or any of our vendors or suppliers contract; 

failure by CROs, SMOs, other third parties or us to adhere to clinical trial requirements; 

failure to perform in accordance with the FDA’s good clinical practices, or GCP, or applicable regulatory guidelines in 
other countries; 

inadequate quantity or quality of a product candidate or other materials necessary to conduct clinical trials, including, 
for example, delays in the testing, validation, manufacturing or delivery of the product candidates to the clinical sites; 

patients not completing participation in a trial or not returning for post-treatment follow-up, including as a result of the 
ongoing COVID-19 pandemic; 

expected or unexpected safety issues, including occurrence of SAEs, associated with any product candidate in clinical 
trials that are viewed as outweighing the product candidate’s potential benefits or reports that may arise from 
preclinical or clinical testing of other similar cancer therapies that raise safety or efficacy concerns about our product 
candidates; 

changes in regulatory requirements or guidance that require amending or submitting new clinical protocols or 
submitting additional data; 

lack of adequate funding to continue one or more clinical trials; or 

geopolitical or other events, including the ongoing COVID-19 pandemic and the current conflict between Russia and 
Ukraine, that unexpectedly disrupt, delay or generally interfere in regional or worldwide operations of our clinical trial 
sites, CROs, SMOs or other operations applicable to the conduct of relevant development activities. 

Delays, including delays caused by the above factors, can be costly and could negatively affect our ability to commence, enroll 
or complete our current and anticipated clinical trials. If we or our collaborators are not able to successfully complete clinical 
trials, we or they will not be able to obtain regulatory approval and will not be able to commercialize our product candidates or 
our collaborators’ product candidates based on our technology. 

An inability to enroll sufficient numbers of patients in our clinical trials could result in increased costs and longer 
development periods for our product candidates. 

Clinical trials require sufficient patient enrollment, which is a function of many factors, including: 

• 

the size and nature of the patient population; 

46 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
• 

• 

• 

• 

• 

• 

• 

• 

• 

the severity of the disease under investigation; 

the nature and complexity of the trial protocol, including eligibility criteria for the trial; 

the design of the trial; 

the number of clinical trial sites and the proximity of patients to those sites; 

the standard of care in the diseases under investigation; 

the ability and commitment of clinical investigators to identify eligible patients; 

clinicians’ and patients’ perceptions of the potential advantages and risks of the drug being studied in relation to other 
available therapies, including any new drugs that may be approved for the indications we are investigating; 

the risk that patients enrolled in clinical trials will drop out of the trials before completion or, because they are late-
stage cancer patients, that they will not survive the full terms of the clinical trials; and 

the ability of our clinical trial sites to continue key activities, such as clinical trial site data monitoring and patient 
visits, due to factors related to the ongoing COVID-19 pandemic or other worldwide events. 

In addition, our clinical trials will compete with other clinical trials for product candidates that are in the same therapeutic areas 
as our current and future product candidates. This competition will reduce the number and types of patients available to us, 
because some patients who might have opted to enroll in our trials may instead opt to enroll in a trial conducted by one of our 
competitors. Since the number of qualified clinical investigators is limited, we expect to conduct some of our clinical trials at 
the same clinical trial sites that some of our competitors use, which will reduce the number of patients who are available for our 
clinical trials at such sites. Moreover, because our current and future product candidates represent a departure from more 
commonly used methods for cancer treatment, potential patients and their doctors may be inclined to use conventional 
therapies, such as chemotherapy, rather than enroll patients in our ongoing or any future clinical trials. 

Challenges in recruiting and enrolling suitable patients to participate in clinical trials that meet the criteria of the protocol could 
increase costs and result in delays to our current development plans for UpRi, XMT-1660, XMT-2056 or any other current or 
future product candidate. 

Our product candidates or ADCs developed or commercialized by our competitors may cause undesirable side effects or 
have other properties that halt their clinical development, delay or prevent regulatory approval of our product candidates or 
limit their commercial potential. 

Undesirable side effects caused by our product candidates or ADCs being developed or commercialized by our collaborators or 
competitors could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive 
label, the denial of regulatory approval by the FDA or other regulatory authorities and potential product liability claims. 
Further, clinical trials by their nature utilize a sample of the potential patient population. With a limited number of subjects and 
limited duration of exposure, rare and severe side effects of our product candidates or those of our competitors may only be 
uncovered with a significantly larger number of patients exposed to the drug. SAEs, including death, deemed to be caused by 
our product candidates or those of our competitors, either before or after receipt of marketing approval, could have a material 
adverse effect on the development of our product candidates and our business as a whole. 

Patients in our ongoing clinical trials have experienced SAEs, including, without limitation, death, pneumonitis, renal 
impairment, abdominal pain, fatigue, vomiting, sepsis and pyrexia. We expect that certain patients in ongoing and future trials 
will experience additional SAEs, including those that may result in death, as our product candidates progress through clinical 
development. These or additional undesirable side effects caused by our product candidates or those of our competitors, either 
before or after receipt of marketing approval, could result in a number of potentially significant negative consequences, 
including: 

• 

• 

our clinical trials may be put on hold; 

treatment-related side effects could affect patient recruitment for our clinical trials; 

47 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
•  we may be unable to obtain regulatory approval for our product candidates; 

• 

• 

• 

regulatory authorities may withdraw or limit their approvals of our product candidates; 

regulatory authorities may require the addition of labeling statements, such as a contraindication, black box warnings 
or additional warnings; 

the FDA may require development of a REMS with Elements to Assure Safe Use as a condition of approval or post-
approval; 

•  we may decide to remove such product candidates from the marketplace; 

•  we may be subject to regulatory investigations and government enforcement actions; 

•  we could be sued and held liable for harm caused to patients; and 

• 

our reputation may suffer. 

Any of these events could prevent us from achieving or maintaining market acceptance of our product candidates and could 
substantially increase commercialization costs. 

We may choose not to develop a potential product candidate, or we may suspend or terminate one or more discovery or 
preclinical programs or product candidates. 

At any time and for any reason, we may determine that one or more of our discovery programs, preclinical programs or product 
candidates does not have sufficient potential to warrant the allocation of resources toward such program or product candidate. 
Furthermore, because we have limited financial and personnel resources, we have placed significant focus on the development 
of our lead product candidate, UpRi, and a limited number of other product candidates, including XMT-1660 and XMT-2056 
and historically including XMT-1592. Accordingly, we may choose not to develop a product candidate or elect to suspend or 
terminate one or more of our discovery or preclinical programs. If we suspend or terminate a program or product candidate in 
which we have invested significant resources, we will have expended resources on a program or product candidate that will not 
provide a full return on our investment. For example, in May 2022, we decided to discontinue development of XMT-1592 based 
in part on the lower prevalence of the NaPi2b biomarker in non-small cell lung cancer, or NSCLC, and the increasingly 
competitive nature of such indication. We may also cease developing a product candidate for a particular indication. For 
example, in November 2021, we determined to cease developing UpRi as a single agent in patients with NSCLC and 
determined to focus development on patients with ovarian cancer. As a result, we may have missed an opportunity to have 
allocated the resources originally used to develop UpRi as a single agent in patients with NSCLC and to develop XMT-1592 to 
potentially more productive uses, including existing or future programs or product candidates. If we do not accurately evaluate 
the commercial potential or target market for a particular future product candidate, we may relinquish valuable rights to future 
product candidates through collaboration, licensing or other royalty arrangements. 

We or our collaborators may fail to discover and develop additional potential product candidates. 

Our and our collaborators’ research programs to identify new product candidates will require substantial technical, financial and 
human resources, and we or our collaborators may be unsuccessful in our or their efforts to identify new product candidates. If 
we or our collaborators are unable to identify suitable additional product candidates for preclinical and clinical development, 
our or their ability to develop product candidates and our ability to obtain revenues from commercializing our products or to 
receive royalties from our collaborators’ sales of their products in future periods could be compromised, which could result in 
significant harm to our financial position and adversely impact our stock price. 

Risks Related to our Financial Position and Need for Additional Capital 

We have incurred net losses since our inception, we have no products approved for commercial sale and we anticipate that 
we will continue to incur substantial operating losses for at least the next several years. We may never achieve or sustain 
profitability. 

We have incurred net losses since our inception. Our net loss was $204.2 million, $170.1 million, and $88.0 million, 
respectively, for the years ended December 31, 2022, 2021, and 2020, respectively. As of December 31, 2022, we had an 
accumulated deficit of $654.7 million. Our losses have resulted principally from costs incurred in our discovery and 

48 

 
 
 
 
 
 
 
 
 
 
 
 
 
development activities. Our net losses may fluctuate significantly from quarter to quarter and year to year. To date, we have not 
commercialized any products or generated any revenues from the sale of products, and we do not expect to generate any 
product revenues in 2023, nor may we generate any product revenues thereafter if we are unable to apply for or obtain 
marketing approvals or gain market acceptance for any approved product(s). Absent the realization of sufficient revenues from 
product sales, we may never achieve profitability in the future.  

We have devoted most of our financial resources to research and development, including our clinical and preclinical 
development activities. To date, we have financed our operations primarily with the proceeds from our strategic collaborations, 
private placements of our preferred stock and public offerings of our common stock, including our initial public offering, our 
follow-on public offerings in 2019 and 2020 and our at-the-market, or ATM, equity offering programs. The amount of our 
future net losses will depend, in part, on the rate of our future expenditures. We have not completed pivotal clinical trials for 
any product candidate and have only a limited number of product candidates in current or planned clinical trials. It will be 
several years, if ever, before we have a product candidate ready for commercialization. Even if we obtain regulatory approval to 
market a product candidate, our future revenues would depend upon the size of the market or markets in which our product 
candidates received such approval and our ability to achieve sufficient market acceptance, reimbursement from third-party 
payors and adequate market share for our product candidates in those markets. 

We expect to continue to incur significant expenses and operating losses over the next several years. We anticipate that our 
expenses will increase significantly in connection with our ongoing activities, as we: 

• 

• 

• 

• 

• 

• 

continue clinical development activities for our lead product candidate, UpRi, and for XMT-1660 and XMT-2056; 

continue to develop a diagnostic assay for the NaPi2b biomarker; 

continue activities to discover, validate and develop additional product candidates; 

obtain marketing approvals for our current and future product candidates for which we complete clinical trials and 
obtain marketing approvals, either ourselves or through a third party, for any necessary companion or complementary 
diagnostics; 

develop a sustainable and scalable manufacturing process for our product candidates, including establishing and 
maintaining commercially viable supply and manufacturing relationships with third parties; 

address any competing technological and market developments; 

•  maintain, expand and protect our intellectual property portfolio; and 

• 

hire additional research, development and general and administrative personnel. 

If we are required by the FDA or any equivalent foreign regulatory authority to perform clinical trials or preclinical trials in 
addition to those we currently expect to conduct, or if there are any delays in completing the clinical trials of UpRi or any other 
current or future product candidates, our expenses could increase. 

To become and remain profitable, we must succeed in developing our product candidates, obtaining regulatory approval for 
them, and manufacturing, marketing and selling those products for which we may obtain regulatory approval. We may not 
succeed in these activities, and we may never generate revenue from product sales or strategic collaborations in an amount 
sufficient to achieve profitability. Even if we achieve profitability in the future, we may not be able to sustain profitability in 
subsequent periods. Our failure to become or remain profitable would depress our market value and could impair our ability to 
raise capital, expand our business, discover or develop other product candidates or continue our operations. 

We have a credit facility that requires us to comply with certain affirmative and negative covenants and places restrictions 
on our operating and financial flexibility. 

In October 2021, we entered into a Loan and Security Agreement, or the New Credit Facility, with Oxford Finance LLC as the 
collateral agent and a lender, SVB as a lender, and the other lenders party thereto, or together the Lenders. Pursuant to the New 
Credit Facility, as amended to date, we may borrow up to an aggregate of $100 million, which includes $40 million available in 
up to four principal advances through June 30, 2023, $40 million in up to one principal advance through September 30, 2023, 
subject to meeting certain development milestones, and an additional tranche of $20 million, which is subject to conditional 
approval from the Lenders. The New Credit Facility is secured by substantially all of our personal property owned or later 

49 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
acquired, excluding intellectual property (but including the right to payments and proceeds from intellectual property), and a 
negative pledge on intellectual property. 

The New Credit Facility also includes customary representations and warranties, affirmative and negative covenants and 
conditions to drawdowns, as well as customary events of default. Certain of the customary negative covenants limit our ability, 
among other things, to incur future debt, grant liens, make investments, make acquisitions, distribute dividends, make certain 
restricted payments and sell assets, subject in each case to certain exceptions. Our failure to comply with these covenants would 
result in an event of default under the Loan and Security Agreement and could result in the acceleration of the obligations we 
owe pursuant to the New Credit Facility. 

We will require substantial additional financing to achieve our goals, and a failure to obtain this necessary capital when 
needed could force us to delay, limit, reduce or terminate our product development or commercialization efforts. 

Our cash, cash equivalents and marketable securities were $280.7 million as of December 31, 2022. We have utilized 
substantial amounts of cash since our inception and expect that we will continue to expend substantial resources for the 
foreseeable future developing UpRi, XMT-1660, XMT-2056 and any other current or future product candidates. These 
expenditures may include costs associated with research and development, conducting preclinical studies and clinical trials, 
potentially obtaining regulatory approvals and manufacturing products, as well as marketing and selling products approved for 
sale, if any, and potentially acquiring new technologies. In addition, other unanticipated costs may arise. Because the outcome 
of our planned and anticipated clinical trials is highly uncertain, we cannot reasonably estimate the actual amounts necessary to 
successfully complete the development and commercialization of our product candidates. Our costs will increase if we 
experience any delays in our clinical trials for UpRi or any other current or future product candidates, including delays in 
enrollment of patients. We also incur costs associated with operating as a public company, hiring additional personnel and 
expanding our facilities. 

Our future capital requirements depend on many factors, including: 

• 

• 

• 

• 

• 

• 

• 

• 

• 

the scope, progress, results and costs of researching and developing UpRi, XMT-1660, XMT-2056 and any other 
current or future product candidates and conducting preclinical studies and clinical trials; 

the timing of, and the costs involved in, obtaining regulatory approvals for UpRi, XMT-1660, XMT-2056 and any 
other current or future product candidates if preclinical studies and clinical trials are successful; 

the cost of manufacturing UpRi, XMT-1660, XMT-2056 and any other current or future product candidates for clinical 
trials in preparation for regulatory approval and in preparation for commercialization; 

the cost of commercialization activities for UpRi, XMT-1660, XMT-2056 and any other current or future product 
candidates, if any product candidates are approved for sale, including manufacturing, marketing, sales and distribution 
costs; 

our ability to establish and maintain strategic collaborations, licensing or other arrangements and the financial terms of 
such agreements; 

the costs involved in preparing, filing, prosecuting, maintaining, defending and enforcing patent claims, including 
litigation costs and the outcome of any such litigation; 

the timing, receipt and amount of sales of, or royalties on, our future products, if any, or products developed by our 
collaborators; 

the emergence of competing cancer therapies and other adverse market developments; and 

the requirement for or the cost of developing companion diagnostics and/or complementary diagnostics. 

50 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
We currently have the option to borrow $15 million under the New Credit Facility. We believe that our current cash, cash 
equivalents and marketable securities, which reflects the receipt in 2023 of a $30 million up-front payment from Merck KGaA 
related to our December 2022 collaboration, plus the available borrowings under the New Credit Facility will be sufficient to 
fund our current operating plan commitments into the second half of 2024. However, we have based these estimates on 
assumptions that may prove to be wrong, and our operating plan may change as a result of many factors currently unknown to 
us and we may need additional funds sooner than planned. Additional funds may not be available when we need them on terms 
that are acceptable to us, or at all. Our ability to borrow funds under the New Credit Facility is subject to us complying with the 
applicable covenants at the time we request a drawdown. If adequate funds are not available to us on a timely basis, we may be 
required to delay, limit, reduce or terminate preclinical studies, clinical trials or other development activities for one or more of 
our product candidates or delay, limit, reduce or terminate our establishment of sales and marketing capabilities or other 
activities that may be necessary to commercialize our product candidates. Even if we believe we have sufficient funds for our 
current or future operating plans, we may seek additional capital due to favorable market conditions or strategic considerations. 

Raising additional capital may cause dilution to our existing stockholders, restrict our operations or require us to relinquish 
rights to our technologies or ADC product candidates. 

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our capital need through a 
variety of means, including through private and public equity offerings, debt financings, collaborations, strategic alliances and 
licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, 
the ownership interests of our common stockholders will be diluted, and the terms of such equity or convertible debt securities 
may include liquidation or other preferences that are senior to or otherwise adversely affect the rights of our common 
stockholders. Additional debt financing, if available, may involve agreements that include covenants limiting or restricting our 
ability to take certain actions, such as incurring future debt, making capital expenditures, declaring dividends or encumbering 
our assets to secure future indebtedness, each of which could adversely impact our ability to conduct our business and execute 
our operating plan. If we raise additional funds through strategic collaborations with third parties, we may have to relinquish 
valuable rights to our technologies, including our platforms, or product candidates, or grant licenses on terms that are not 
favorable to us. If we are unable to raise additional funds through equity or debt financing when needed, we may be required to 
delay, limit, reduce or terminate our product development or commercialization efforts for UpRi, XMT-1660, XMT-2056 or any 
other current or future product candidates or grant rights to third parties to develop and market product candidates that we 
would otherwise prefer to develop and market ourselves. 

We may expend our resources to pursue a particular product candidate and fail to capitalize on product candidates that may 
be more profitable or for which there is a greater likelihood of success. 

Because we have limited financial and managerial resources, we focus on specific product candidates. As a result, we may 
forgo or delay pursuit of opportunities with other product candidates that later prove to have greater commercial potential. Our 
resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market 
opportunities. Failure to properly assess potential product candidates could result in our focus on product candidates with low 
market potential, which would harm our business and financial condition. Our spending on current and future research and 
development programs and product candidates for specific indications may not yield any commercially viable product 
candidates. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we 
may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases 
in which it would have been more advantageous for us to retain sole development and commercialization rights to such product 
candidate. 

51 

 
 
 
 
 
Risks Related to Our Reliance on Third Parties 

Because we rely on third-party manufacturers and suppliers, our supply of research and development, preclinical and 
clinical development materials may become limited or interrupted or may not be of satisfactory quantity or quality. 

We rely on third-party contract manufacturers to manufacture our preclinical and clinical trial product supplies, and we lack the 
internal resources and the capability to manufacture any product candidates on a clinical or commercial scale. The facilities 
used by our contract manufacturers to manufacture the active pharmaceutical ingredient and final drug product must be 
acceptable to the FDA and other comparable foreign regulatory agencies pursuant to inspections that would be conducted after 
we submit our marketing application or relevant foreign regulatory submission to the applicable regulatory agency. There can 
be no assurance that our preclinical and clinical development product supplies will be sufficient, uninterrupted or of satisfactory 
quality or continue to be available at acceptable prices. If our contract manufacturers cannot successfully manufacture material 
that conforms to our specifications and the strict regulatory requirements of the FDA or applicable foreign regulatory agencies, 
they will not be able to secure or maintain regulatory approval for their manufacturing facilities. Any replacement of our 
manufacturers could require significant effort and expertise because there may be a limited number of qualified replacements. 

The manufacturing process for a product candidate is subject to FDA and foreign regulatory authority review. Suppliers and 
manufacturers must meet applicable manufacturing requirements and undergo rigorous facility and process validation tests 
required by regulatory authorities in order to comply with regulatory standards, such as current good manufacturing practices. 
We have no direct control over our contract manufacturers’ ability to maintain adequate quality control, quality assurance and 
qualified personnel. In the event that any of our manufacturers fails to comply with regulatory requirements or to perform its 
obligations to us in relation to quality, timing or otherwise, or if our supply of components or other materials becomes limited 
or interrupted for other reasons, we may be forced to manufacture the materials ourselves, for which we currently do not have 
the capabilities or resources, or enter into an agreement with another third party, which we may not be able to do on reasonable 
terms, if at all. In some cases, the technical skills or technology required to manufacture our product candidates may be unique 
or proprietary to the original manufacturer, and we may have difficulty transferring such skills or technology to another third 
party and a feasible alternative may not exist. These factors would increase our reliance on such manufacturer or require us to 
obtain a license from such manufacturer in order to have another third-party manufacture our product candidates. If we are 
required to change manufacturers for any reason, we will be required to verify that the new manufacturer maintains facilities 
and procedures that comply with quality standards and with all applicable regulations and guidelines. The delays associated 
with the verification of a new manufacturer could negatively affect our ability to develop product candidates in a timely manner 
or within budget. Our reliance on contract manufacturers also exposes us to the possibility that they, or third parties with access 
to their facilities, will have access to and may appropriate our trade secrets or other proprietary information. 

We expect to continue to rely on third-party manufacturers if we receive regulatory approval for any product candidate. To the 
extent that we have existing, or enter into future, manufacturing arrangements with third parties, we will depend on these third 
parties to perform their obligations in a timely manner consistent with contractual and regulatory requirements, including those 
related to quality control and assurance. If we are unable to obtain or maintain third-party manufacturing for product 
candidates, or to do so on commercially reasonable terms, we may not be able to develop and commercialize our product 
candidates successfully. Our or a third party’s failure to execute on our manufacturing requirements and comply with cGMP 
could adversely affect our business in a number of ways, including: 

• 

• 

• 

• 

• 

• 

• 

a delay or inability to initiate or continue clinical trials of product candidates under development; 

delay in submitting regulatory applications, or delay or failure to receive regulatory approvals, for product candidates; 

loss of the cooperation of an existing or future strategic collaborator; 

subjecting third-party manufacturing facilities or our manufacturing facilities to additional inspections by regulatory 
authorities; 

a requirement to cease distribution or to recall batches of our product candidates; 

in the event of approval to market and commercialize a product candidate, an inability to meet commercial demands 
for our products; and 

fines, adverse publicity, and civil and criminal enforcement and sanctions. 

52 

 
 
 
 
 
 
 
 
 
 
 
We, or our third-party manufacturers, may be unable to successfully scale-up manufacturing of our ADC product 
candidates in sufficient quality and quantity, which would delay or prevent us from developing our ADC product candidates 
and commercializing approved products, if any. 

In order to conduct clinical trials of our product candidates and commercialize any approved product candidates, we, or our 
third-party manufacturers, will need to manufacture them in large quantities. We, or our third-party manufacturers, may be 
unable to successfully increase the manufacturing capacity for any of our product candidates in a timely or cost-effective 
manner, or at all. In addition, quality issues may arise during scale-up activities. If we or any third-party manufacturer are 
unable to successfully scale up the manufacture of our product candidates in sufficient quality and quantity, the development, 
testing and clinical trials of that product candidate may be delayed or infeasible, and regulatory approval or commercial launch 
of any resulting product may be delayed or not obtained, which could significantly harm our business. We have evaluated 
which third-party manufacturers to engage for scale-up to commercial supply of our product candidates, including UpRi, and 
we have begun to transfer and scale-up certain manufacturing activities. If we are unable to obtain or maintain third-party 
manufacturing for commercial supply of our product candidates, or to do so on commercially reasonable terms, we may not be 
able to develop and commercialize our product candidates successfully. 

We rely on third parties to conduct preclinical studies and clinical trials for UpRi, XMT-1660, XMT-2056 and our other 
product candidates, and if such third parties do not properly, timely and successfully perform their obligations to us, we may 
not be able to obtain regulatory approvals for UpRi, XMT-1660, XMT-2056 or any other current or future ADC product 
candidates. 

We designed the ongoing and planned clinical trials for UpRi, XMT-1660 and XMT-2056, as well as the trial for XMT-1592 
that closed in September 2022, and we intend to design any future clinical trials for any future product candidates that we may 
develop if preclinical studies are successful and we do not have a strategic collaborator responsible for such trial design. 
However, we rely on CROs, SMOs, clinical sites, investigators and other third parties to assist in managing, monitoring and 
otherwise carrying out many of these trials. As a result, we have less direct control over the conduct, timing and completion of 
these clinical trials and the management of data developed through clinical trials than would be the case if we were relying 
entirely upon our own staff. These CROs, SMOs, investigators and other third parties are not our employees, and we have 
limited control over the amount of time and resources that they dedicate to our programs. We compete with many other 
companies for the resources of these third parties. These third parties may have contractual relationships with other entities, 
some of which may be our competitors, which may draw time and resources from our programs. The third parties with whom 
we contract might not be diligent, careful or timely in conducting our preclinical studies or clinical trials, or complying with 
current good laboratory practices or current good clinical practices, as applicable, resulting in the preclinical studies or clinical 
trials being delayed or unsuccessful. 

The third parties on whom we rely generally may terminate their engagements at any time, and having to enter into alternative 
arrangements would delay development and commercialization of our product candidates. Communicating with outside parties 
can also be challenging, potentially leading to mistakes as well as difficulties in coordinating activities. Outside parties may: 

• 

• 

• 

• 

• 

have staffing difficulties; 

fail to comply with contractual obligations; 

experience regulatory compliance issues; 

undergo changes in priorities or become financially distressed; or 

form relationships with other entities, some of which may be our competitors. 

The FDA and comparable foreign regulatory authorities require compliance with regulations and standards, including GCP, for 
designing, conducting, monitoring, recording, analyzing and reporting the results of clinical trials to assure that the data and 
results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. Although we 
rely, and intend to continue to rely, on third parties to conduct our clinical trials, they are not our employees, and we are 
responsible for ensuring that each of these clinical trials is conducted in accordance with its general investigational plan, 
protocol and other requirements. Our reliance on these third parties for research and development activities will reduce our 
control over these activities but will not relieve us of our responsibilities. For any violations of laws or regulations during the 
conduct of our clinical trials, we could be subject to untitled and warning letters or enforcement action that may include civil 
penalties up to and including criminal prosecution. 

53 

 
 
 
 
 
 
 
 
 
 
 
 
If these third parties do not successfully carry out their duties under their agreements, if the quality or accuracy of the data they 
obtain is compromised due to their failure to adhere to clinical trial protocols or to regulatory requirements, or if they otherwise 
fail to comply with clinical trial protocols or meet expected deadlines, the clinical trials of our product candidates may not meet 
regulatory requirements. The FDA enforces GCP regulations through periodic inspections of clinical trial sponsors, principal 
investigators and trial sites. If we or our CROs fail to comply with applicable GCPs or other regulatory requirements, the 
clinical data generated in our clinical trials may be deemed unreliable, third parties may need to be replaced, we may be subject 
to negative publicity, fines and civil or criminal sanctions, and preclinical development activities or clinical trials may be 
extended, delayed, suspended or terminated. If any of these events occur, we may not be able to obtain regulatory approval of 
our product candidates on a timely basis or at all. 

We depend on strategic relationships with other companies to assist in the research, development and commercialization of 
our ADC platforms and ADC product candidates. If our existing collaborators do not perform as expected, this may 
negatively affect our ability to commercialize our ADC product candidates or generate revenues through technology 
licensing or may otherwise negatively affect our business. 

We have established strategic collaborations and intend to continue to establish strategic collaborations and other relationships 
with third parties to research, develop and commercialize our platforms and existing and future product candidates. In 
December 2022, we entered into a collaboration and license agreement with Ares Trading, S.A., an affiliate of Merck KGaA, 
for the research, development and commercialization of ADC product candidates leveraging our Immunosynthen platform, and 
in February 2022, we entered into a collaboration agreement with Janssen Biotech, Inc. for the research, development and 
commercialization of ADC product candidates leveraging our Dolasynthen platform. We had also entered into a collaboration 
agreement with Merck KGaA for the development and commercialization of ADC product candidates leveraging our Dolaflexin 
platform. Additionally, in August 2022, we entered into an option, collaboration and license agreement, or the GSK Agreement, 
with GlaxoSmithKline Intellectual Property (No. 4) Limited, or GSK, pursuant to which we granted GSK an exclusive option to 
obtain an exclusive license to co-develop and to commercialize products containing XMT-2056. Under these arrangements, we 
will depend on our collaborators to design and conduct their clinical trials. As a result, we will not be able to control or oversee 
the conduct of these programs by our collaborators and those programs may not be successful, which may negatively impact 
our business operations. In addition, if any of these collaborators withdraw support for these programs or proposed products or 
otherwise impair their development or experience negative results, our business and our product candidates could be negatively 
affected. 

Our collaborators may terminate their agreements with us for cause under certain circumstances or at will in certain cases and 
discontinue use of our technologies. In addition, we cannot control the amount and timing of resources our collaborators may 
devote to products utilizing or incorporating our technology. Moreover, our relationships with our collaborators may divert 
significant time and effort of our scientific staff and management team and require effective allocation of our resources to 
multiple internal and collaborative projects. Our collaborators may fail to perform their obligations under the collaboration 
agreements or may not perform their obligations in a timely manner. If conflicts arise between our collaborators and us, the 
other party may act in a manner adverse to us and could limit our ability to implement our strategies. If any of our collaborators 
terminate or breach our agreements with them, or otherwise fail to complete their obligations in a timely manner, or if GSK 
ultimately decides not to exercise its option for a license to co-develop and commercialize XMT-2056, it may have a 
detrimental effect on our financial position by reducing or eliminating the potential for us to receive technology access and 
license fees, milestones and royalties, reimbursement of development costs, as well as possibly requiring us to devote additional 
efforts and incur costs associated with pursuing internal development of product candidates. Furthermore, if our collaborators 
do not prioritize and commit sufficient resources to programs associated with our product candidates or collaboration product 
candidates, we or our collaborators may be unable to commercialize these product candidates, which would limit our ability to 
generate revenue and become profitable. 

Our collaborators may separately pursue competing products, therapeutic approaches or technologies to develop treatments for 
the diseases targeted by us or our collaborators. Competing products, either developed by our collaborators or to which our 
collaborators have rights, may result in the withdrawal of collaborators support for our product candidates. Even if our 
collaborators continue their contributions to the strategic relationships, they may nevertheless determine not to actively pursue 
the development or commercialization of any resulting products. Additionally, if our collaborators pursue different clinical or 
regulatory strategies with their product candidates based on our platforms or technologies, adverse events with their product 
candidates could negatively affect our product candidates utilizing similar technologies. Any of these developments could harm 
our product development efforts. 

To date, we have depended on a small number of collaborators for a substantial portion of our revenue. The loss of any one 
of these collaborators could result in non-achievement of our expected revenue payments. 

54 

 
 
 
 
 
 
 
We have entered into strategic collaborations with a limited number of companies. To date, a substantial portion of our revenue 
has resulted from payments made under agreements with our strategic collaborators, and we expect that a portion of our 
revenue will continue to come from strategic collaborations. The loss of any of our collaborators, or the failure of our 
collaborators to perform their obligations under their agreements with us, including paying license or technology fees, 
milestone payments, royalties or reimbursements, could have a material adverse effect on our financial performance. Payments 
under our existing and future strategic collaborations are also subject to significant fluctuations in both timing and amount, 
which could cause our revenue to fall below the expectations of securities analysts and investors and cause a decrease in our 
stock price. 

We may seek to establish additional strategic collaborations, and if we are not able to establish them on commercially 
reasonable terms, or maintain them, we may have to alter our development and commercialization plans. 

We continue to strategically evaluate our collaborations and, as appropriate, we expect to enter into additional strategic 
collaborations in the future, including potentially with major biotechnology or biopharmaceutical companies. We face 
significant competition in seeking appropriate collaborators for our product candidates and platforms, and the negotiation 
process is time-consuming and complex. In order for us to successfully collaborate with a third-party to leverage our platforms 
or advance our product candidates, potential collaborators must view these platforms and product candidates as economically 
valuable in markets they determine to be attractive in light of the terms that we are seeking and other available platforms and 
products for licensing by other companies. Even if we are successful in our efforts to establish strategic collaborations, the 
terms that we agree upon may not be favorable to us, and we may not be able to maintain such strategic collaborations if, for 
example, development or approval of a product candidate is delayed or sales of an approved product are disappointing. Any 
delay in entering into strategic collaboration agreements related to our product candidates or platforms could delay the 
development and commercialization of existing or future product candidates and reduce their competitiveness even if they 
reach the market. If we are not able to generate revenue under our strategic collaborations when and in accordance with our 
expectations or the expectations of industry analysts, this failure could harm our business and have an immediate adverse effect 
on the trading price of our common stock. 

If we fail to establish and maintain additional strategic collaborations related to our product candidates for which we have not 
yet entered into a strategic collaboration, we will bear all of the risk and costs related to the development of any such product 
candidate, and we may need to seek additional financing, hire additional employees and otherwise develop expertise, such as 
regulatory expertise, for which we have not budgeted. If we are not successful in seeking additional financing, hiring additional 
employees or developing additional expertise, if necessary, our cash burn rate would increase or we would need to take steps to 
reduce our rate of product candidate development. This could negatively affect the development of any product candidate for 
which we do not currently have a collaborator. 

Risks Related to Commercialization of Our ADC Product Candidates 

Our  future  commercial  success  depends  upon  attaining  significant  market  acceptance  of  our ADC  product  candidates,  if 
approved, among physicians, patients and health care payors. 

Even  if  we  obtain  regulatory  approval  for  UpRi  or  any  other  current  or  future  product  candidates  that  we  may  develop  or 
acquire in the future, the product candidate may not gain market acceptance among physicians, health care payors, patients and 
the broader healthcare community. Market acceptance of any approved products depends on a number of factors, including: 

• 

• 

• 

• 

• 

• 

• 

the efficacy and safety of the product, as demonstrated in clinical trials; 

the  indications  for  which  the  product  is  approved  and  the  label  approved  by  regulatory  authorities  for  use  with  the 
product, including any warnings that may be required on the label; 

acceptance by physicians and patients of the product as a safe and effective treatment; 

the cost, safety and efficacy of treatment in relation to alternative treatments; 

the availability of adequate reimbursement and pricing by third-party payors and government authorities; 

relative convenience and ease of administration; 

the prevalence and severity of adverse side effects; and 

55 

 
 
 
 
 
 
 
 
 
 
• 

the effectiveness of our sales and marketing efforts. 

Perceptions of any product are influenced by perceptions of competitors’ products. As a result, adverse public perception of our 
competitors’ products may negatively impact the market acceptance of our product candidates. Market acceptance is critical to 
our ability to generate significant revenue and become profitable. Any therapeutic candidate, if approved and commercialized, 
may be accepted in only limited capacities or not at all. If any approved products are not accepted by the market to the extent 
that we expect, we may not be able to generate significant revenue and our business would suffer. 

The incidence and prevalence for target patient populations of our drug candidates have not been established with precision. 
If the market opportunities for our drug candidates, including particularly UpRi, are smaller than we estimate, or if any 
approval that we obtain is based on a narrower definition of the patient population, our revenue and ability to achieve 
profitability will be adversely affected, possibly materially. 

The precise incidence and prevalence of ovarian cancer with NaPi2b expression are uncertain. Our estimates of both the 
number of people who have this disease, as well as the subset of people with ovarian cancer who have the potential to benefit 
from treatment with UpRi, are based on estimates. The total addressable market opportunity for UpRi for the treatment of 
ovarian cancer with NaPi2b positive expression, if UpRi is approved for sale for this indication, will ultimately depend upon, 
among other things, the diagnosis criteria included in the final label for UpRi, acceptance by the medical community, the 
approval and availability of a commercial diagnostic assay to identify patients with NaPi2b positive ovarian cancer, and patient 
access, drug pricing and reimbursement. The number of patients who can be treated with UpRi or any of our other current or 
future product candidates may turn out to be lower than expected, patients may not be otherwise amenable to treatment with our 
drugs, we may face increasing difficulties in identifying or gaining access to new patients, or diagnostic assays to help identify 
patients may not be available, all of which would adversely affect our results of operations and our business. 

If we are unable to establish sales, marketing and distribution capabilities, we may not be successful in commercializing our 
product candidates if and when they are approved. 

We do not have a sales or marketing infrastructure and have no experience in the sale, marketing or distribution of products. To 
achieve commercial success for any product for which we have obtained marketing approval, we will need to establish a sales 
and marketing organization or pursue a collaborative arrangement for such sales and marketing. 

In the future, we expect to build a focused sales and marketing infrastructure to market UpRi and XMT-1660 and any other 
current or future product candidates in the United States and certain foreign jurisdictions, if and when they are approved, and 
we may potentially do so for XMT-2056. There are risks involved with establishing our own sales, marketing and distribution 
capabilities. 

For example, recruiting and training a sales force is expensive and time consuming and could delay any product launch. If the 
commercial launch of a product candidate for which we recruit a sales force and establish marketing capabilities is delayed or 
does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This 
may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel. 
Factors that may inhibit our efforts to commercialize our products on our own include: 

• 

• 

• 

• 

• 

our inability to recruit, train and retain adequate numbers of effective sales and marketing personnel; 

the inability of sales personnel to obtain access to physicians; 

the lack of adequate numbers of physicians to prescribe any future products; 

the lack of complementary products to be offered by sales personnel, which may put us at a competitive disadvantage 
relative to companies with more extensive product lines; and 

unforeseen costs and expenses associated with creating an independent sales and marketing organization. 

If we are unable to establish our own sales, marketing and distribution capabilities and enter into arrangements with third 
parties to perform these services, our product revenues and our profitability, if any, are likely to be lower than if we were to 
market, sell and distribute any products that we develop ourselves. 

In addition, we may not be successful in entering into arrangements with third parties to sell, market and distribute certain of 
our product candidates outside of the United States or may be unable to do so on terms that are favorable to us. We likely will 

56 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
have limited control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and 
market our products effectively. If we do not establish sales, marketing and distribution capabilities successfully, either on our 
own or in collaboration with third parties, we will not be successful in commercializing our product candidates. 

Reimbursement may be limited or unavailable in certain market segments for our ADC product candidates, which could 
make it difficult for us to sell our products profitably. 

In both domestic and foreign markets, sales of any of our product candidates, if approved, will depend, in part, on the extent to 
which the costs of our products will be covered by third-party payors, such as government health programs, commercial 
insurance and managed health care organizations. These third-party payors decide which drugs will be covered and establish 
reimbursement levels for those drugs. The containment of health care costs has become a priority of foreign and domestic 
governments as well as private third-party payors. The prices of drugs have been a focus in this effort. Governments and private 
third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular 
medications, which could affect our ability to sell our product candidates profitably. Cost-control initiatives could cause us to 
decrease the price we might establish for products, which could result in lower than anticipated product revenues. 

Reimbursement by a third-party payor may depend upon a number of factors, including the third-party payor’s determination 
that use of a product is: 

• 

• 

• 

• 

• 

a covered benefit under its health plan; 

safe, effective and medically necessary; 

appropriate for the specific patient; 

cost-effective; and 

neither experimental nor investigational. 

Adverse pricing limitations may hinder our ability to recoup our investment in UpRi, XMT-1660, XMT-2056 or any other 
current or future product candidates, even if such product candidates obtain marketing approval. 

Obtaining coverage and reimbursement approval for a product from a government or other third-party payor is a time 
consuming and costly process that could require us to provide supporting scientific, clinical and cost-effectiveness data for the 
use of our products to the payor. Further, there is significant uncertainty related to third-party payor coverage and 
reimbursement of newly approved drugs. We may not be able to provide data sufficient to gain acceptance with respect to 
coverage and reimbursement. We cannot be sure that coverage or adequate reimbursement will be available for any of our 
product candidates. Also, we cannot be sure that reimbursement amounts will not reduce the demand for, or the price of, our 
products. If reimbursement is not available or is available only to limited levels, we may not be able to commercialize certain of 
our products. In addition, in the United States, third-party payors are increasingly attempting to contain health care costs by 
limiting both coverage and the level of reimbursement of new drugs. As a result, significant uncertainty exists as to whether and 
how much third-party payors will reimburse patients for their use of newly approved drugs, which in turn will put pressure on 
the pricing of drugs. Manufacturers further may be required to offer price concessions to achieve sales or favorable coverage. 

Price controls may be imposed in foreign markets, which may adversely affect our future profitability. 

In some countries, including member states of the European Union, the pricing of prescription drugs is subject to governmental 
control. Additional countries may adopt similar approaches to the pricing of prescription drugs. In such countries, pricing 
negotiations with governmental authorities can take considerable time after receipt of marketing approval for a product. In 
addition, there can be considerable pressure by governments and other stakeholders on prices and reimbursement levels, 
including as part of cost containment measures. Political, economic and regulatory developments may further complicate 
pricing negotiations, and pricing negotiations may continue after reimbursement has been obtained. Reference pricing used by 
various European Union member states and parallel distribution, or arbitrage between low-priced and high-priced member 
states, can further reduce prices. In some countries, we may be required to conduct a clinical trial or other trials that compare 
the cost-effectiveness of our product candidates to other available therapies in order to obtain or maintain reimbursement or 
pricing approval. We cannot be sure that such prices and reimbursement will be acceptable to us or our strategic collaborators. 
Publication of discounts by third-party payors or authorities may lead to further pressure on the prices or reimbursement levels 
within the country of publication and other countries. If pricing is set at unsatisfactory levels or if reimbursement of our 

57 

 
 
 
 
 
 
 
 
 
 
 
 
 
products is unavailable or limited in scope or amount, our revenues from sales by us or our strategic collaborators and the 
potential profitability of our product candidates in those countries would be negatively affected. 

We face substantial competition, and if our competitors develop and market products that are more effective, safer or less 
expensive than any of our current or future product candidates, our commercial opportunities will be negatively impacted. 

The biotechnology and biopharmaceutical industries are characterized by rapidly advancing technologies, intense competition 
and a strong emphasis on proprietary products. Many third parties compete with us in developing various approaches to cancer 
therapy. They include pharmaceutical companies, biotechnology companies, academic institutions and other research 
organizations. Any treatments developed by our competitors could be superior to our product candidates. It is possible that 
these competitors will succeed in developing technologies that are more effective than our platforms or product candidates or 
that would render our platforms obsolete, noncompetitive or not economical. We anticipate that we will face increased 
competition in the future as additional companies enter our market and scientific developments surrounding other cancer 
therapies continue to accelerate. 

We are also aware of multiple companies with ADC technologies that may be competitive to our platforms, including Daiichi 
Sankyo Company, Limited; ImmunoGen, Inc.; Gilead Sciences, Inc.; Pfizer Inc.; and Seagen Inc. These companies or their 
partners and collaborators, including Astellas Pharma Inc.; AstraZeneca plc; AbbVie Inc.; Genentech, a member of the Roche 
Group; and Takeda Pharmaceuticals, Inc., to Takeda, may develop product candidates that compete in the same indications as 
our current and future product candidates. Multiple companies are also developing ADCs that could compete with our 
Immunosynthen product candidates, including Bolt Biotherapeutics, Inc. and Takeda, albeit with differing immune stimulating 
approaches. We expect to compete based on our innovative technology and the efficacy, safety and tolerability profile of our 
ADCs compared to other product candidates, but if our ADCs are not demonstrably superior in these respects, we may not be 
able to compete effectively. Products we may develop in the future are also likely to face competition from other products and 
therapies, some of which we may not currently be aware. 

Many of our competitors have significantly greater financial resources and expertise in research and development, 
manufacturing, preclinical studies, conducting clinical trials, obtaining regulatory approval and marketing than we do. In 
addition, many of these competitors are active in seeking patent protection and licensing arrangements in anticipation of 
collecting royalties for use of technology that they have developed. Large pharmaceutical companies, in particular, have 
extensive experience in clinical testing, obtaining marketing approvals, establishing clinical trial sites, recruiting patients and in 
manufacturing pharmaceutical products and may succeed in discovering, developing and commercializing products in our field 
before we do. Smaller or early-stage companies may also prove to be significant competitors, particularly through strategic 
relationships with large and established companies. These third parties compete with us in recruiting and retaining qualified 
scientific and management personnel, as well as in acquiring technologies complementary to our programs. 

In addition, if our product candidates are approved and commercialized, we may face competition from biosimilars. The route 
to market for biosimilars was established with the passage of the Health Care Reform Act in March 2010. The Biologics Price 
Competition and Innovation Act of 2009, or BPCIA, establishes a pathway for FDA approval of follow-on biologics and 
provides 12 years of data exclusivity for reference products. The BPCIA is complex and continues to be interpreted and 
implemented by the FDA. In addition, government proposals have sought to reduce the 12-year reference product exclusivity 
period. Further, since the BPCIA was enacted as part of the overall Health Care Reform Act, current litigation challenges to that 
Act, discussed more in full below, could impact the validity of the BPCIA. As a result, there still remains significant uncertainty 
as to the ultimate impact, implementation and regulatory interpretation of the BPCIA. 

In Europe, the European Medicines Agency, or EMA, has issued guidelines for approving products through an abbreviated 
pathway, and biosimilars have been approved in Europe. If a biosimilar version of one of our potential products were approved 
in the United States or Europe, it could have a negative effect on sales and gross profits of the potential product and our 
financial condition. 

With respect to our current and potential future product candidates, we believe that our ability to compete effectively and 
develop products that can be manufactured cost-effectively and marketed successfully will depend on our ability to: 

• 

• 

• 

advance our technology platforms; 

obtain and maintain intellectual property protection for our technologies and products; 

obtain required government and other public and private approvals on a timely basis; 

58 

 
 
 
 
 
 
 
 
 
 
 
 
• 

• 

• 

• 

• 

attract and retain key personnel; 

commercialize effectively; 

obtain reimbursement for our products in approved indications; 

comply with applicable laws, regulations and regulatory requirements and restrictions with respect to the 
commercialization of our products, including with respect to any changed or increased regulatory restrictions; and 

enter into additional strategic collaborations to advance the development and commercialization of our product 
candidates. 

Risks Related to Our Intellectual Property 

If we are unable to obtain or protect intellectual property rights related to our technology and ADC product candidates, or if 
our intellectual property rights are inadequate, we may not be able to compete effectively. 

Our success depends in large part on our ability to obtain and maintain protection with respect to our intellectual property and 
proprietary technology. We rely upon a combination of patents, trade secret protection and confidentiality agreements to protect 
the intellectual property related to our platforms and our product candidates, including UpRi, XMT-1660 and XMT-2056. The 
patent position of biopharmaceutical companies is generally uncertain because it involves complex legal and factual 
considerations and has, in recent years, been the subject of much litigation. As a result, the issuance, scope, validity, 
enforceability and commercial value of our patent rights is highly uncertain. The standards applied by the United States Patent 
and Trademark Office, or USPTO, and foreign patent offices in granting patents are not always applied uniformly or 
predictably. For example, there is no uniform worldwide policy regarding patentable subject matter or the scope of claims 
allowable in patents. In addition, changes in either the patent laws or interpretation of the patent laws in the United States and 
other countries may diminish the value of our patents or narrow the scope of our patent protection. The patent prosecution 
process is expensive, complex and time-consuming, and we may not be able to file, prosecute, maintain, enforce or license all 
necessary or desirable patents and patent applications at a reasonable cost or in a timely manner. It is also possible that we fail 
to identify patentable aspects of our research and development output before it is too late to obtain patent protection. There is no 
assurance that all potentially relevant prior art relating to our patents and patent applications has been found. We may be 
unaware of prior art that could be used to invalidate an issued patent or prevent our pending patent applications from issuing as 
patents. 

The patent applications that we own or in-license may fail to result in issued patents, and even if they do issue as patents, such 
patents may not cover our platforms and product candidates in the United States or in other countries. The issuance of a patent 
is not conclusive as to its inventorship, scope, validity or enforceability, and our patents may be challenged in the courts or 
patent offices in the United States and abroad. Such challenges may result in loss of exclusivity or in patent claims being 
narrowed, invalidated or held unenforceable, which could limit our ability to stop others from using or commercializing similar 
or identical technology and products, or limit the duration of the patent protection of our technology and product candidates. 
For example, even if patent applications we license or own do successfully issue as patents and even if such patents cover our 
platforms and product candidates, third parties may challenge their validity, enforceability or scope, which may result in such 
patents being narrowed or invalidated. Furthermore, even if they are unchallenged, our patents and patent applications may not 
provide adequate protection or exclusivity for our ADC platform or product candidates, prevent others from designing around 
our claims or otherwise provide us with a competitive advantage. Any of these outcomes could impair our ability to prevent 
competition from third parties, which may have an adverse impact on our business. 

If patent applications we own or have in-licensed with respect to our platforms or our product candidates fail to issue as patents, 
if their breadth or strength of protection is threatened, or if they fail to provide meaningful exclusivity, it could dissuade 
companies from collaborating with us. We cannot offer any assurances about which, if any, patents will issue, the breadth of 
any such patents or whether any issued patents will be found invalid and unenforceable or will be threatened by third parties. 
Any successful challenge to these patents or any other patents owned by or licensed to us could deprive us of rights necessary 
for the successful development and commercialization of any product candidate. Since patent applications in the United States 
and most other countries are confidential for a period of time after filing, and some remain so until issued, we cannot be certain 
that we were the first to file any patent application related to a product candidate. Furthermore, if third parties have filed such 
patent applications, an interference proceeding in the United States can be initiated by the USPTO or a third-party to determine 
who was the first to invent any of the subject matter covered by the patent claims of our applications. In addition, patents have a 
limited lifespan. In the United States, the natural expiration of a patent is generally 20 years after it is filed. Various extensions 
may be available; however, the life of a patent and the protection it affords is limited. Given the amount of time required for the 

59 

 
 
 
 
 
 
 
 
development, testing and regulatory review of new product candidates, our owned or in-licensed patents protecting such 
candidates might expire before or shortly after such candidates are commercialized. If we encounter delays in obtaining 
regulatory approvals, the period of time during which we could market a drug under patent protection could be further reduced. 
Even if patents covering our product candidates are obtained, once the patent life has expired for a product, we may be open to 
competition from similar or generic products. The launch of a generic version of one of our products in particular would be 
likely to result in an immediate and substantial reduction in the demand for our product, which could have a material adverse 
effect on our business, financial condition, results of operations and prospects. 

On September 16, 2011, the Leahy-Smith America Invents Act, or the Leahy-Smith Act, was signed into law. The Leahy-Smith 
Act includes a number of significant changes to U.S. patent law. These include provisions that affect the way patent 
applications are prosecuted, redefine prior art, may affect patent litigation and switch the U.S. patent system from a “first-to-
invent” system to a “first-to-file” system. Under a first-to-file system, assuming the other requirements for patentability are met, 
the first inventor to file a patent application generally will be entitled to the patent on an invention regardless of whether 
another inventor had made the invention earlier. These provisions also allow third-party submission of prior art to the USPTO 
during patent prosecution and set forth additional procedures to attack the validity of a patent by the USPTO administered post 
grant proceedings. The USPTO developed additional regulations and procedures to govern administration of the Leahy-Smith 
Act, and many of the substantive changes to patent law associated with the Leahy-Smith Act, and, in particular, the first-to-file 
provisions, became effective on March 16, 2013. Accordingly, it is not clear what, if any, impact the Leahy-Smith Act will have 
on the operation of our business. The Leahy-Smith Act and its implementation could increase the uncertainties and costs 
surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of which could 
have a material adverse effect on our business, financial condition, results of operations and prospects. 

Any loss of patent protection could have a material adverse impact on our business. We may be unable to prevent competitors 
from entering the market with a product that is similar to or the same as our product candidates. 

Issued patents covering UpRi, XMT-1660, XMT-2056 and any other current or future ADC product candidates could be 
found invalid or unenforceable if challenged in court or before the USPTO or comparable foreign authority. 

If we or one of our licensing partners initiate legal proceedings against a third party to enforce a patent covering UpRi, XMT-
1660, XMT-2056 or any other current or future product candidates, the defendant could counterclaim that the patent covering 
our product candidate is invalid or unenforceable. In patent litigation in the United States, defendant counterclaims alleging 
invalidity or unenforceability are commonplace, and there are numerous grounds upon which a third party can assert invalidity 
or unenforceability of a patent. Grounds for a validity challenge could be, among other things, an alleged failure to meet any of 
several statutory requirements, including lack of novelty, obviousness, lack of written description or non-enablement. Grounds 
for an unenforceability assertion could be, among other things, an allegation that someone connected with prosecution of the 
patent withheld relevant information from the USPTO, or made a misleading statement, during prosecution. Third parties may 
also raise similar claims before administrative bodies in the United States or abroad, even outside the context of litigation. Such 
mechanisms include re-examination, inter partes review, post-grant review, interference proceedings, derivation proceedings 
and equivalent proceedings in foreign jurisdictions (e.g., opposition proceedings). Such proceedings could result in revocation, 
cancellation or amendment to our patents in such a way that they no longer cover and protect our product candidates. The 
outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to the validity of our 
patents, for example, we cannot be certain that there is no invalidating prior art of which we, our licensors, our patent counsel 
and the patent examiner were unaware during prosecution. If a third party were to prevail on a legal assertion of invalidity or 
unenforceability, we would lose at least part, and perhaps all, of the patent protection on one or more of our product candidates. 
Any such loss of patent protection could have a material adverse impact on our business, financial condition, results of 
operations and prospects. 

If we fail to comply with our obligations under any license, strategic collaboration or other agreements, we may be required 
to pay damages and could lose intellectual property rights that are necessary for developing and protecting our ADC product 
candidates. 

60 

 
 
 
 
 
 
 
We rely, in part, on license, collaboration and other agreements. We may need to obtain additional licenses from others to 
advance our research or allow commercialization of our product candidates and it is possible that we may be unable to obtain 
additional licenses at a reasonable cost or on reasonable terms, if at all. The licensing or acquisition of third party intellectual 
property rights is a competitive area, and several more established companies may pursue strategies to license or acquire third 
party intellectual property rights that we may consider attractive. These established companies may have a competitive 
advantage over us due to their size, capital resources and greater clinical development and commercialization capabilities. In 
addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to use. We also may be 
unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return 
on our investment. 

In addition, our existing licenses and collaboration agreements, including our licenses with Ares Trading S.A., a wholly owned 
subsidiary of Merck KGaA, Darmstadt, Germany, or Merck KGaA, and Merck KGaA for intellectual property covering the 
Immunosynthen and Dolaflexin platforms; our potential license with GlaxoSmithKline Intellectual Property (No. 4) Limited, or 
GSK, for intellectual property covering XMT-2056; our license with Janssen Biotech, Inc., or Janssen, for intellectual property 
covering the Dolasynthen platform; our license with with Recepta Biopharma S.A., or Recepta, for intellectual property 
covering the NaPi2b antibody in UpRi; and our license with Synaffix B.V., or Synaffix, for intellectual property covering 
components included in the Dolasynthen platform, impose, and any future licenses, collaborations or other agreements we enter 
into are likely to impose, various development, commercialization, funding, milestone, royalty, diligence, sublicensing, 
insurance, patent prosecution and enforcement or other obligations on us. If we breach any of these obligations, or use the 
intellectual property licensed to us in an unauthorized manner, we may be required to pay damages and the licensor may have 
the right to terminate the license, including, in the case of our agreements with Merck KGaA, the license for the rights covering 
the Immunosynthen and Dolaflexin platforms; in the case of our agreement with GSK, the potential license for the rights 
covering XMT-2056; in the case of our agreement with Janssen, the license for the rights covering the Dolasynthen platform; in 
the case of our agreement with Recepta, the license for the rights covering the NaPi2b antibody in UpRi; and, in the case of our 
agreement with Synaffix, the license for the rights covering components in the Dolasynthen platform. Any of the foregoing 
could result in us being unable to develop, manufacture and sell products that are covered by the licensed technology or enable 
a competitor to gain access to the licensed technology. Disputes may arise regarding intellectual property subject to a licensing, 
collaboration or other agreements, including: 

• 

• 

• 

• 

• 

the scope of rights granted under the license agreement and other interpretation related issues; 

the extent to which our technology and processes infringe on intellectual property of the licensor that is not subject to 
the licensing agreement; 

the sublicensing of patent and other rights under our collaborative development relationships; 

our diligence obligations under the license agreement and what activities satisfy those diligence obligations; 

the inventorship and ownership of inventions and know how resulting from the joint creation or use of intellectual 
property by our licensors and us and our collaborators; and 

• 

the priority of invention of patented technology. 

In addition, the agreements under which we currently license intellectual property or technology to or from third parties are 
complex, and certain provisions in such agreements may be susceptible to multiple interpretations. The resolution of any 
contract interpretation disagreement that may arise could narrow what we believe to be the scope of our rights to the relevant 
intellectual property or technology, or increase what we believe to be our financial or other obligations under the relevant 
agreement, either of which could have a material adverse effect on our business, financial condition, results of operations and 
prospects. Moreover, if disputes over intellectual property that we have licensed prevent or impair our ability to maintain our 
current licensing arrangements on commercially acceptable terms, we may be unable to successfully develop and 
commercialize the affected product candidates. 

In some circumstances, we may not have the right to control the preparation, filing and prosecution of patent applications, or to 
maintain the patents, covering the technology that we license from third parties. For example, pursuant to our license agreement 
with Recepta, Ludwig Institute for Cancer Research Ltd., a co-owner of the intellectual property, retains control of such 
activities. Therefore, we cannot be certain that these patents and applications will be prosecuted, maintained and enforced in a 
manner consistent with the best interests of our business. If our licensors fail to obtain or maintain such intellectual property, or 
lose rights to such intellectual property, the rights we have licensed and our exclusivity may be reduced or eliminated and our 
right to develop and commercialize any of our products that are subject to such licensed rights could be adversely affected. 

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Moreover, our rights to our in-licensed patents and patent applications are dependent, in part, on inter-institutional or other 
operating agreements between the joint owners of such in-licensed patents and patent applications. If one or more of such joint 
owners breaches such inter-institutional or operating agreements, our rights to such in-licensed patents and patent applications 
may be adversely affected. In addition, while we cannot currently determine the amount of the royalty obligations we would be 
required to pay on sales of future products, if any, the amounts may be significant. The amount of our future royalty obligations 
will depend on the technology and intellectual property we use in products that we successfully develop and commercialize, if 
any. Therefore, even if we successfully develop and commercialize products, we may be unable to achieve or maintain 
profitability. Any of the foregoing could have a material adverse effect on our competitive position, business, financial 
conditions, results of operations and prospects. 

If we are unable to successfully obtain rights to required third-party intellectual property rights or maintain the existing 
intellectual property rights we have, we may have to abandon development of the relevant program or product candidate and 
our business, financial condition, results of operations and prospects could suffer. 

We may become involved in lawsuits to protect or enforce our intellectual property or to defend against intellectual property 
claims, which could be expensive, time consuming and unsuccessful. 

Competitors and other third parties may infringe our patents or misappropriate or otherwise violate our owned and in-licensed 
intellectual property rights. To counter infringement or unauthorized use, litigation or other intellectual property proceedings 
may be necessary to enforce or defend our owned and in-licensed intellectual property rights, to protect our trade secrets or to 
determine the validity and scope of our own intellectual property rights or the proprietary rights of others. Such litigation or 
proceedings can be expensive and time consuming, and any such claims could provoke defendants to assert counterclaims 
against us, including claims alleging that we infringe their patents or other intellectual property rights. We may not have 
sufficient financial or other resources to adequately conduct such litigation or proceedings. Many of our current and potential 
competitors have the ability to dedicate substantially greater resources to litigate intellectual property rights than we can and 
have more mature and developed intellectual property portfolios. Accordingly, despite our efforts, we may not be able to 
prevent third parties from infringing upon or misappropriating our intellectual property. Even if resolved in our favor, litigation 
or other intellectual property proceedings could result in substantial costs and diversion of management attention and resources, 
which could harm our business and financial results. 

In addition, in a litigation or other proceeding, a court or administrative judge may decide that a patent owned by or licensed to 
us is invalid or unenforceable, or a court may refuse to stop the other party from using the technology at issue on the grounds 
that our patents do not cover the technology in question. An adverse result in any litigation or other proceeding could put one or 
more of our patents at risk of being invalidated, held unenforceable or interpreted narrowly. Furthermore, because of the 
substantial amount of discovery required in connection with intellectual property litigation and other proceedings, there is a risk 
that some of our confidential information could be compromised by disclosure during this type of litigation. During the course 
of any patent or other intellectual property litigation or other proceeding, there could be public announcements of the results of 
hearings, rulings on motions and other interim proceedings or developments and if securities analysts or investors regard these 
announcements as negative, the perceived value of our product candidates, programs or intellectual property could be 
diminished. Accordingly, the market price of our common stock may decline. Any of the foregoing could have a material 
adverse effect on our business, financial conditions, results of operations and prospects. 

Third-party claims of intellectual property infringement or misappropriation may prevent or delay our development and 
commercialization efforts. 

Our commercial success depends in part on our ability and the ability of our strategic collaborators to develop, manufacture, 
market and sell product candidates and use our proprietary technologies without infringing, misappropriating or otherwise 
violating the patents and proprietary rights of third parties. There is a substantial amount of litigation, both within and outside 
the United States, involving patent and other intellectual property rights in the biopharmaceutical industries, including patent 
infringement lawsuits, interferences, oppositions, reexamination, inter partes review, derivation and post grant review 
proceedings before the USPTO and corresponding foreign patent offices. Numerous U.S. and foreign issued patents and 
pending patent applications owned by third parties exist in the fields in which we are developing and may develop our product 
candidates. As the biopharmaceutical industries expand and more patents are issued, the risk increases that our product 
candidates may be subject to claims of infringement of the patent rights of third parties. 

Third parties may assert that we, our customers, licensees or parties indemnified by us are employing their proprietary 
technology without authorization or have infringed upon, misappropriated or otherwise violated their intellectual property or 
other rights, regardless of their merit. For example, we may be subject to claims that we are infringing the patent, trademark or 
copyright rights of third parties, or that our employees have misappropriated or divulged their former employers’ trade secrets 

62 

 
 
 
 
 
 
 
 
or confidential information. There may be third-party patents or patent applications with claims to materials, formulations, 
methods of manufacture or methods for treatment related to the use or manufacture of our product candidates, that we failed to 
identify. For example, applications filed before November 29, 2000 and certain applications filed after that date that will not be 
filed outside the United States remain confidential until issued as patents. Except for certain exceptions, including the preceding 
exceptions, patent applications in the United States and elsewhere are generally published only after a waiting period of 
approximately 18 months after the earliest filing, and sometimes not at all. Therefore, patent applications covering our 
platforms or our product candidates could have been filed by others without our knowledge. Additionally, pending patent 
applications which have been published can, subject to certain limitations, be later amended in a manner that could cover our 
platforms, our product candidates or the use or manufacture of our product candidates. 

Even if we believe a third party’s claims against us are without merit, a court of competent jurisdiction could hold that such 
third party’s patent is valid, enforceable and covers aspects of our product candidates, including the materials, formulations, 
methods of manufacture, methods of analysis, or methods for treatment, in which case, such third party would be able to block 
our ability to develop and commercialize the applicable technology or product candidate until such patent expired or unless we 
obtain a license and we may be required to pay such third-party monetary damages, which could be substantial. Such licenses 
may not be available on acceptable terms, if at all. Even if we were able to obtain a license, the rights may be nonexclusive, 
which could result in our competitors gaining access to the same intellectual property and it could require us to make 
substantial licensing and royalty payments. Ultimately, we could be prevented from commercializing a product, or be forced to 
cease some aspect of our business operations, if, as a result of actual or threatened patent infringement claims, we are unable to 
enter into licenses on acceptable terms. 

Parties making claims against us may also obtain injunctive or other equitable relief, which could effectively block our ability 
to further develop and commercialize our technologies or one or more of our product candidates. Defending against claims of 
patent infringement, misappropriation of trade secrets or other violations of intellectual property could be costly and time 
consuming, regardless of the outcome. Thus, even if we were to ultimately prevail, or to settle at an early stage, such litigation 
could burden us with substantial unanticipated costs. In addition, litigation or threatened litigation could result in significant 
demands on the time and attention of our management team, distracting them from the pursuit of other company business. In 
the event of a successful claim of infringement against us, in addition to potential injunctive relief, we may have to pay 
substantial damages, including treble damages and attorneys’ fees for willful infringement, pay royalties, redesign our 
infringing products or obtain one or more licenses from third parties, which may be impossible or require substantial time and 
monetary expenditure. 

We may face a claim of misappropriation if a third party believes that we inappropriately obtained and used trade secrets of 
such third party. If we are found to have misappropriated a third party’s trade secrets, we may be prevented from further using 
such trade secrets, limiting our ability to develop our product candidates, we may be required to obtain a license to such trade 
secrets which may not be available on commercially reasonable terms or at all and may be non-exclusive, and we may be 
required to pay damages, which could be substantial. Any of the foregoing could have a material adverse effect on our business, 
financial condition, results of operations and prospects. 

We may not be able to protect our intellectual property and proprietary rights throughout the world. 

Filing, prosecuting and defending patents on product candidates in all countries throughout the world where we expect there to 
be significant markets for our products could be prohibitively expensive, and the laws of foreign countries may not protect our 
rights to the same extent as the laws of the United States. In addition, our intellectual property license agreements may not 
always include worldwide rights. For example, certain U.S. and foreign issued patents and patent applications are licensed to us 
by Recepta on a worldwide basis, except that Recepta retains exclusive rights in such patents and patent applications in Brazil. 
Consequently, we may not be able to prevent third parties from practicing our inventions in all countries outside the United 
States. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their 
own products and, further, may export otherwise infringing products to territories where we have patent protection or licenses 
but enforcement is not as strong as that in the United States. These products may compete with our products, and our patents or 
other intellectual property rights may not be effective or sufficient to prevent them from competing. 

Additionally, the laws of some foreign countries do not protect intellectual property rights to the same extent as the laws of the 
United States, and many companies have encountered significant problems in protecting and defending such rights in foreign 
jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of 
patents and other intellectual property protection, particularly those relating to biotechnology, which could make it difficult for 
us to stop the infringement of our licensed and owned patents or marketing of competing products in violation of our 
intellectual property and proprietary rights generally. Proceedings to enforce our intellectual property and proprietary rights in 
foreign jurisdictions could result in substantial costs and divert our efforts and attention from other aspects of our business, 

63 

 
 
 
 
 
 
 
could put our patents at risk of being invalidated or interpreted narrowly, could put our patent applications at risk of not issuing 
as patents, and could provoke third parties to assert claims against us. We may not prevail in any lawsuits that we initiate, and 
the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, our efforts to enforce our 
intellectual property and proprietary rights around the world may be inadequate to obtain a significant commercial advantage 
from the intellectual property that we develop or license. 

Many countries have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third 
parties. In addition, many countries limit the enforceability of patents against government agencies or government contractors. 
In these countries, the patent owner may have limited remedies, which could materially diminish the value of such patent. If we 
or any of our licensors is forced to grant a license to third parties with respect to any patents relevant to our business, our 
competitive position may be impaired, and our business, financial condition, results of operations and prospects may be 
adversely affected. 

Confidentiality agreements with employees and third parties may not prevent unauthorized disclosure of trade secrets and 
other proprietary information. 

In addition to the protection afforded by patents, we rely on trade secret protection and confidentiality agreements to protect 
proprietary know-how that is not patentable or that we elect not to patent, processes for which patents are difficult to enforce 
and any other elements of our platform technology and discovery and development processes that involve proprietary know-
how, information or technology that is not covered by patents. However, trade secrets can be difficult to protect. We seek to 
protect our proprietary technology and processes, in part, by entering into confidentiality agreements with our employees, 
consultants and outside scientific advisors, contractors and collaborators. We cannot guarantee that we have entered into such 
agreement with each party that may have or have had access to our trade secrets or proprietary technology and processes. 
Additionally, our confidentiality agreements and other contractual protections may not be adequate to protect our intellectual 
property from unauthorized disclosure, third-party infringement or misappropriation. We may not have adequate remedies in 
the case of a breach of any such agreements, and our trade secrets and other proprietary information could be disclosed to our 
competitors or others may independently develop substantially equivalent or superior proprietary information and techniques or 
otherwise gain access to our trade secrets or disclose such technologies. 

Enforcing a claim that a third party illegally obtained and is using any of our trade secrets is expensive and time consuming, 
and the outcome is unpredictable. In addition, some courts outside and within the United States sometimes are less willing to 
protect trade secrets. Misappropriation or unauthorized disclosure of our trade secrets could impair our competitive position and 
may have a material adverse effect on our business. 

We may be subject to claims by third parties asserting that our licensors, employees, consultants, advisors or we have 
misappropriated their intellectual property, or claiming ownership of what we regard as our own intellectual property. 

Many of our and our licensors’ employees, including our senior management, consultants or advisors are currently, or 
previously were, employed at universities or other biotechnology or pharmaceutical companies, including our competitors or 
potential competitors. Some of these employees, including members of our senior management, executed proprietary rights, 
non-disclosure and non-competition agreements, or similar agreements, in connection with such previous employment. 
Although we try to ensure that our employees, consultants and advisors do not use the proprietary information or know-how of 
others in their work for us, we may be subject to claims that we or these individuals have used or disclosed intellectual property, 
including trade secrets or other proprietary information, of any such individual’s current or former employer. Litigation may be 
necessary to defend against such claims. If we fail in defending any such claims, in addition to paying monetary damages, we 
may lose valuable intellectual property rights or personnel or sustain damages. Such intellectual property rights could be 
awarded to a third party, and we could be required to obtain a license from such third party to commercialize our technology or 
products. Such a license may not be available on commercially reasonable terms or at all. Even if we are successful in 
defending against such claims, litigation could result in substantial costs and be a distraction to management. Any of the 
foregoing may have a material adverse effect on our business, financial condition, results of operations and prospects. 

In addition, while it is our policy to require our employees and contractors who may be involved in the conception or 
development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful 
in executing such an agreement with each party who, in fact, conceives or develops intellectual property that we regard as our 
own. The assignment of intellectual property rights may not be self-executing or the assignment agreements may be breached, 
and we may be forced to bring claims against third parties, or defend claims that they may bring against us, to determine the 
ownership of what we regard as our intellectual property. 

64 

 
 
 
 
 
 
 
 
 
If we do not obtain patent term extension and data exclusivity for any product candidates we may develop, our business may 
be materially harmed. 

Depending upon the timing, duration and specifics of any FDA marketing approval of any product candidates we may develop, 
one or more of our owned or in-licensed U.S. patents may be eligible for limited patent term extension under the Drug Price 
Competition and Patent Term Restoration Act of 1984, or Hatch-Waxman Amendments. The Hatch-Waxman Amendments 
permit a patent term extension of up to five years as compensation for the patent term lost during the FDA regulatory review 
process. A patent term extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of 
product approval, only one patent may be extended and only those claims covering the approved drug, a method for using it or 
a method for manufacturing it may be extended. However, we may not be granted an extension because of, for example, failing 
to exercise due diligence during the testing phase or regulatory review process, failing to apply within applicable deadlines, 
failing to apply prior to expiration of relevant patents, or otherwise failing to satisfy applicable requirements. Moreover, the 
applicable time period or the scope of patent protection afforded could be less than we request. If we are unable to obtain patent 
term extension or the term of any such extension is less than we request, our competitors may obtain approval of competing 
products following our patent expiration, and our business, financial condition, results of operations and prospects could be 
materially harmed. 

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee 
payment, and other requirements imposed by government patent agencies, and our patent protection could be reduced or 
eliminated for non-compliance with these requirements. 

Periodic maintenance fees, renewal fees, annuity fees and various other government fees on patents and patent applications will 
be due to be paid to the USPTO and various government patent agencies outside of the United States over the lifetime of our 
owned or licensed patents and applications. In certain circumstances, we rely on our licensing partners to pay these fees due to 
U.S. and non-U.S. patent agencies. The USPTO and various non-U.S. government agencies require compliance with several 
procedural, documentary, fee payment and other similar provisions during the patent application process. We are also dependent 
on our licensors to take the necessary action to comply with these requirements with respect to our licensed intellectual 
property. In some cases, an inadvertent lapse can be cured by payment of a late fee or by other means in accordance with the 
applicable rules. There are situations, however, in which non-compliance can result in abandonment or lapse of the patent or 
patent application, resulting in a partial or complete loss of patent rights in the relevant jurisdiction. In such an event, potential 
competitors might be able to enter the market with similar or identical products or technology, which could have a material 
adverse effect on our business, financial condition, results of operations and prospects. 

Intellectual property rights do not necessarily address all potential threats. 

The degree of future protection afforded by our intellectual property rights is uncertain because intellectual property rights have 
limitations and may not adequately protect our business or permit us to maintain our competitive advantage. For example: 

• 

others may be able to make ADC products that are similar to any product candidates we may develop or utilize similar 
ADC-related technology but that are not covered by the claims of the patents that we license or may own in the future; 

•  we, or our license partners or current or future strategic collaborators, might not have been the first to make the 
inventions covered by the issued patent or pending patent application that we license or may own in the future; 

•  we, or our license partners or current or future strategic collaborators, might not have been the first to file patent 

applications covering certain of our or their inventions; 

• 

• 

• 

• 

others may independently develop similar or alternative technologies or duplicate any of our technologies without 
infringing our owned or licensed intellectual property rights; 

it is possible that our pending licensed patent applications or those that we may own in the future will not lead to 
issued patents; 

issued patents that we hold rights to may be held invalid or unenforceable, including as a result of legal challenges by 
our competitors; 

our competitors might conduct research and development activities in countries where we do not have patent rights 
and then use the information learned from such activities to develop competitive products for sale in our major 
commercial markets; 

65 

 
 
 
 
 
 
 
 
 
 
 
 
 
•  we may not develop additional proprietary technologies that are patentable; 

• 

the patents of others may harm our business; and 

•  we may choose not to file a patent in order to maintain certain trade secrets or know how, and a third party may 

subsequently file a patent covering such intellectual property. 

Should any of these events occur, they could have a material adverse effect on our business, financial condition, results of 
operations and prospects. 

Risks Related to Regulatory Approval and Other Legal Compliance Matters 

Even if we complete the necessary preclinical studies and clinical trials, the regulatory approval process is expensive, time 
consuming and uncertain and may prevent us from obtaining approvals for the commercialization of some or all of our 
product candidates. As a result, we cannot predict when or if, and in which territories, we will obtain marketing approval to 
commercialize a product candidate. 

The research, testing, manufacturing, labeling, approval, selling, marketing, promotion and distribution of products are subject 
to extensive regulation by the FDA and comparable foreign regulatory authorities. We are not permitted to market our product 
candidates in the United States or in other countries until we receive approval of a biologics license application, or BLA, from 
the FDA or marketing approval from applicable regulatory authorities outside the United States. Our product candidates are in 
various stages of development and are subject to the risks of failure inherent in development. We have not submitted an 
application for or received marketing approval for any of our product candidates in the United States or in any other 
jurisdiction. While we have announced that we expect data from our UPLIFT clinical trial of UpRi in mid-2023 which, if 
positive, we expect would support our submission of a BLA for UpRi for the treatment of platinum-resistant ovarian cancer 
under the FDA's accelerated approval pathway around the end of 2023, there can be no guarantee that these data will be 
positive or sufficient to support approval of UpRi by the FDA. Additionally, we have no experience as a company in filing and 
supporting the applications necessary to gain marketing approvals and expect to rely on third-party CROs to assist us in this 
process. 

The process of obtaining marketing approvals, both in the United States and abroad, is lengthy, expensive and uncertain. It may 
take many years, if approval is obtained at all, and can vary substantially based upon a variety of factors, including the type, 
complexity and novelty of the product candidates involved. Securing marketing approval requires the submission of extensive 
preclinical and clinical data and supporting information, including manufacturing information, to regulatory authorities for each 
therapeutic indication to establish the product candidate’s safety and efficacy. The FDA or other regulatory authorities may 
determine that our product candidates are not safe and effective, only moderately effective or have undesirable or unintended 
side effects, toxicities or other characteristics that preclude our obtaining marketing approval or prevent or limit commercial 
use. 

In addition, changes in marketing approval policies during the development period, changes in or the enactment or 
promulgation of additional statutes, regulations or guidance or changes in regulatory review for each submitted product 
application, may cause delays in the approval or rejection of an application. Regulatory authorities have substantial discretion in 
the approval process and varying interpretations of the data obtained from preclinical and clinical testing could delay, limit or 
prevent marketing approval of a product candidate. Any marketing approval we ultimately obtain may be limited or subject to 
restrictions or post-approval commitments that render the approved product not commercially viable. 

Failure to obtain marketing approval in foreign jurisdictions would prevent our product candidates from being marketed 
abroad. Any approval we may be granted for our product candidates in the United States would not assure approval of our 
product candidates in foreign jurisdictions and any of our product candidates that may be approved for marketing in a 
foreign jurisdiction will be subject to risks associated with foreign operations. 

66 

 
 
 
 
 
 
 
 
 
 
 
 
We intend to market our current product candidates, UpRi, XMT-1660 and XMT-2056, if approved, in international markets 
either directly or through collaborations. In order to market and sell our products in the European Union and other foreign 
jurisdictions, we must obtain separate marketing approvals and comply with numerous and varying regulatory requirements. 
The approval procedure varies among countries and can involve additional testing. The time required to obtain approval may 
differ substantially from that required to obtain FDA approval. The marketing approval process outside the United States 
generally includes all of the risks associated with obtaining FDA approval. We may not obtain approvals from regulatory 
authorities outside the United States on a timely basis, if at all. Approval by the FDA does not ensure approval by regulatory 
authorities in other countries or jurisdictions, and approval by one regulatory authority outside the United States does not ensure 
approval by regulatory authorities in other countries or jurisdictions or by the FDA. We may file for marketing approvals but 
not receive necessary approvals to commercialize our products in any market. 

In many countries outside the United States, a product candidate must also be approved for reimbursement before it can be sold 
in that country. In some cases, the price that we intend to charge for our products, if approved, is also subject to approval. 
Obtaining non-U.S. regulatory approvals and compliance with non-U.S. regulatory requirements could result in significant 
delays, difficulties and costs for us and could delay or prevent the introduction of our product candidates in certain countries. In 
addition, if we fail to obtain the non-U.S. approvals required to market our product candidates outside the United States or if we 
fail to comply with applicable non-U.S. regulatory requirements, our target markets will be reduced and our ability to realize 
the full market potential of our product candidates will be harmed and our business, financial condition, results of operations 
and prospects may be adversely affected. 

In addition, following the result of a referendum in 2016, the United Kingdom left the European Union on January 31, 2020, 
commonly referred to as Brexit. After lapse of a transition period, the United Kingdom is no longer part of the European Single 
Market and European Union Customs Union as of January 1, 2021. A trade and cooperation agreement that outlined the future 
trading relationship between the United Kingdom and the European Union was agreed to in December 2020 and entered into 
force on May 1, 2021. As of January 1, 2021, the Medicines and Healthcare products Regulatory Agency, or the MHRA, 
became responsible for supervising medicines and medical devices in Great Britain, comprising England, Scotland and Wales 
under domestic law, whereas Northern Ireland will continue to be subject to EU rules under the Northern Ireland Protocol. The 
MHRA will rely on the Human Medicines Regulations 2012 (SI 2012/1916) (as amended), or the HMR, as the basis for 
regulating medicines. The HMR has incorporated into the domestic law of the body of EU law instruments governing medicinal 
products that pre-existed prior to the United Kingdom’s withdrawal from the European Union.  

Since a significant proportion of the regulatory framework for pharmaceutical products in the United Kingdom covering the 
quality, safety, and efficacy of pharmaceutical products, clinical trials, marketing authorization, commercial sales, and 
distribution of pharmaceutical products is derived from EU directives and regulations, Brexit may have a material impact upon 
the regulatory regime with respect to the development, manufacture, importation, approval and commercialization of our 
product candidates in the United Kingdom. For example, the United Kingdom is no longer covered by the centralized 
procedures for obtaining EU-wide marketing authorization from the EMA, and a separate marketing authorization will be 
required to market our product candidates in the United Kingdom. Until December 31, 2023, it is possible for the MHRA to 
rely on a decision taken by the European Commission on the approval of a new marketing authorization via the centralized 
procedure. However, it is unclear whether the MHRA in the United Kingdom is sufficiently prepared to handle the increased 
volume of marketing authorization applications that it is likely to receive after such time. Any delay in obtaining, or an inability 
to obtain, any marketing approvals, as a result of Brexit or otherwise, may force us to restrict or delay efforts to seek regulatory 
approval in the United Kingdom for our product candidates, which could significantly and materially harm our business. 

We expect that we will be subject to additional risks in commercializing any of our product candidates that receive marketing 
approval outside the United States, including tariffs, trade barriers and regulatory requirements; economic weakness, including 
inflation, or political instability in particular foreign economies and markets; compliance with tax, employment, immigration 
and labor laws for employees living or traveling abroad; foreign currency fluctuations, which could result in increased 
operating expenses and reduced revenue, and other obligations incident to doing business in another country; and workforce 
uncertainty in countries where labor unrest is more common than in the United States. 

Any product candidate for which we obtain marketing approval is subject to ongoing regulation and could be subject to 
restrictions or withdrawal from the market, and we may be subject to substantial penalties if we fail to comply with 
regulatory requirements, when and if any of our product candidates are approved.  

Any product candidate for which we obtain marketing approval will be subject to continual requirements of and review by the 
FDA and other regulatory authorities. These requirements include submissions of safety and other post-marketing information 
and reports, registration and listing requirements, cGMP requirements relating to quality control and manufacturing, quality 

67 

 
 
 
 
 
 
 
assurance and corresponding maintenance of records and documents, and requirements regarding the distribution of samples to 
physicians and recordkeeping. In addition, the approval may be subject to limitations on the indicated uses for which the 
product may be marketed or to the conditions of approval, or contain requirements for costly post-marketing testing and 
surveillance to monitor the safety or efficacy of the medicine, including the requirement to implement a risk evaluation and 
mitigation strategy. Accordingly, if we receive marketing approval for one or more of our product candidates, we will continue 
to expend time, money and effort in all areas of regulatory compliance, including manufacturing, production, product 
surveillance and quality control. If we fail to comply with these requirements, we could have the marketing approvals for our 
products withdrawn by regulatory authorities and our ability to market any products could be limited, which could adversely 
affect our ability to achieve or sustain profitability. 

We must also comply with requirements concerning advertising and promotion for any of our product candidates for which we 
obtain marketing approval. Promotional communications with respect to prescription products are subject to a variety of legal 
and regulatory restrictions and must be consistent with the information in the product’s approved labeling. Thus, we will not be 
able to promote any products we develop for indications or uses for which they are not approved. The FDA and other agencies, 
including the Department of Justice, closely regulate and monitor the post-approval marketing and promotion of products to 
ensure that they are marketed and distributed only for the approved indications and in accordance with the provisions of the 
approved labeling. In September 2021, the FDA published final regulations which describe the types of evidence that the 
agency will consider in determining the intended use of a drug or biologic. Moreover, with passage of the Pre-approval 
Information Exchange Act in December 2022, sponsors of products that have not been approved may proactively communicate 
to payors certain information about products in development to help expedite patient access upon product approval. Violations 
of the Federal Food, Drug, and Cosmetic Act and other statutes, including the False Claims Act, relating to the promotion and 
advertising of prescription products may lead to investigations and enforcement actions alleging violations of federal and state 
health care fraud and abuse laws, as well as state consumer protection laws. 

Failure to comply with regulatory requirements, may yield various results, including: 

• 

• 

• 

• 

restrictions on such products, manufacturers or manufacturing processes; 

restrictions on the labeling or marketing of a product; 

restrictions on distribution or use of a product; 

requirements to conduct post-marketing studies or clinical trials; 

•  warning letters or untitled letters; 

•  withdrawal of the products from the market; 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

refusal to approve pending applications or supplements to approved applications that we submit; 

recall of products; 

damage to relationships with collaborators; 

unfavorable press coverage and damage to our reputation; 

fines, restitution or disgorgement of profits or revenues; 

suspension or withdrawal of marketing approvals; 

refusal to permit the import or export of our products; 

product seizure; 

injunctions or the imposition of civil or criminal penalties; and 

litigation involving patients using our products. 

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Similar restrictions apply to the approval of our products in the European Union. The holder of a marketing authorization is 
required to comply with a range of requirements applicable to the manufacturing, marketing, promotion and sale of medicinal 
products. These include compliance with the European Union’s stringent pharmacovigilance or safety reporting rules, which 
can impose post-authorization studies and additional monitoring obligations; the manufacturing of authorized medicinal 
products, for which a separate manufacturer’s license is mandatory; and the marketing and promotion of authorized drugs, 
which are strictly regulated in the European Union and are also subject to EU Member State laws. 

Accordingly, in connection with our currently approved products and assuming we, or our collaborators, receive marketing 
approval for one or more of our product candidates, we, and our collaborators, and our and their contract manufacturers will 
continue to expend time, money and effort in all areas of regulatory compliance, including manufacturing, production, product 
surveillance and quality control. If we, and our collaborators, are not able to comply with post-approval regulatory 
requirements, our or our collaborators’ ability to market any future products could be limited, which could adversely affect our 
ability to achieve or sustain profitability. Further, the cost of compliance with post-approval regulations may have a negative 
effect on our operating results and financial condition. 

We may seek certain designations for our product candidates, including but not limited to Breakthrough Therapy, Fast 
Track and Priority Review designations in the United States, and PRIME Designation in the European Union, but we might 
not receive such designations, and even if we do, such designations may not lead to a faster development or regulatory 
review or approval process. 

We have in the past sought and may also in the future seek certain designations for one or more of our product candidates that 
could expedite review and approval by the FDA. A Breakthrough Therapy product is defined as a product that is intended, alone 
or in combination with one or more other products, to treat a serious condition, and preliminary clinical evidence indicates that 
the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, 
such as substantial treatment effects observed early in clinical development. For products that have been designated as 
Breakthrough Therapies, interaction and communication between the FDA and the sponsor of the trial can help to identify the 
most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens. 

The FDA may also designate a product for Fast Track review if it is intended, whether alone or in combination with one or 
more other products, for the treatment of a serious or life threatening disease or condition, and it demonstrates the potential to 
address unmet medical needs for such a disease or condition. For Fast Track products, sponsors may have greater interactions 
with the FDA and the FDA may initiate review of sections of a Fast Track product’s application before the application is 
complete. This rolling review may be available if the FDA determines, after preliminary evaluation of clinical data submitted by 
the sponsor, that a Fast Track product may be effective. The FDA has granted Fast Track designation for UpRi for the treatment 
of patients with platinum-resistant high-grade serous ovarian cancer who have received up to three prior lines of systemic 
therapy or patients who have received four prior lines of systemic therapy regardless of platinum status, and the FDA has 
granted Fast Track designation for XMT-1660 for the treatment of adult patients with advanced or metastatic triple-negative 
breast cancer. 

We may also seek a priority review designation for one or more of our product candidates. If the FDA determines that a product 
candidate offers major advances in treatment or provides a treatment where no adequate therapy exists, the FDA may designate 
the product candidate for priority review. A priority review designation means that the goal for the FDA to review an 
application is six months, rather than the standard review period of ten months. 

These designations are within the discretion of the FDA. Accordingly, even if we believe that one of our product candidates 
meets the criteria for these designations, the FDA may disagree and instead determine not to make such designation. Further, 
even if we receive a designation, the receipt of such designation for a product candidate may not result in a faster development 
or regulatory review or approval process compared to products considered for approval under conventional FDA procedures 
and does not assure ultimate approval by the FDA. In addition, even if one or more of our product candidates qualifies for these 
designations, the FDA may later decide that the product candidates no longer meet the conditions for qualification or decide 
that the time period for FDA review or approval will not be shortened. 

In the European Union, we may seek PRIME designation for our product candidates in the future. PRIME is a voluntary 
program aimed at enhancing the EMA’s role to reinforce scientific and regulatory support in order to optimize development and 
enable accelerated assessment of new medicines that are of major public health interest with the potential to address unmet 
medical needs. The program focuses on medicines that target conditions for which there exists no satisfactory method of 
treatment in the European Union or even if such a method exists, it may offer a major therapeutic advantage over existing 
treatments. PRIME is limited to medicines under development and not authorized in the European Union and the applicant 
intends to apply for an initial marketing authorization application through the centralized procedure. To be accepted for PRIME, 

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a product candidate must meet the eligibility criteria in respect of its major public health interest and therapeutic innovation 
based on information that is capable of substantiating the claims. 

The benefits of a PRIME designation include the appointment of a CHMP rapporteur to provide continued support and help to 
build knowledge ahead of a marketing authorization application, early dialogue and scientific advice at key development 
milestones, and the potential to qualify products for accelerated review, meaning reduction in the review time for an opinion on 
approvability to be issued earlier in the application process. PRIME enables an applicant to request parallel EMA scientific 
advice and health technology assessment advice to facilitate timely market access. Even if we receive PRIME designation for 
any of our product candidates, the designation may not result in a materially faster development process, review or approval 
compared to conventional EMA procedures. Further, obtaining PRIME designation does not assure or increase the likelihood of 
EMA’s grant of a marketing authorization. 

We have received orphan drug designations for XMT-2056 and UpRi, but we may not be able to obtain orphan drug 
exclusivity for any additional product candidates, and even if we do, that exclusivity may not prevent the FDA or EMA from 
approving other competing products. 

Under the Orphan Drug Act, the FDA may designate a product as an orphan drug if it is a drug or biologic intended to treat a 
rare disease or condition. A similar regulatory scheme governs approval of orphan products by the EMA in the European Union. 
Generally, if a product candidate with an orphan drug designation subsequently receives the first marketing approval for the 
indication for which it has such designation, the product is entitled to a period of marketing exclusivity, which precludes the 
FDA or EMA from approving another marketing application for the same product for the same therapeutic indication for that 
time period. The applicable period is seven years in the United States and ten years in the European Union. The exclusivity 
period in the European Union can be reduced to six years if a product no longer meets the criteria for orphan drug designation, 
in particular if the product is sufficiently profitable so that market exclusivity is no longer justified. 

In order for the FDA to grant orphan drug exclusivity to one of our products, the agency must find that the product is indicated 
for the treatment of a condition or disease with a patient population of fewer than 200,000 individuals annually in the United 
States. The FDA may conclude that the condition or disease for which we seek orphan drug exclusivity does not meet this 
standard. Even if we obtain orphan drug exclusivity for a product, that exclusivity may not effectively protect the product from 
competition because different products can be approved for the same condition. In particular, the concept of what constitutes 
the “same drug” for purposes of orphan drug exclusivity remains in flux in the context of gene therapies, and the FDA issued 
final guidance suggesting that it would not consider two genetic medicine products to be different drugs solely based on minor 
differences in the transgenes or vectors within a given vector class. In addition, even after an orphan drug is approved, the FDA 
can subsequently approve the same product for the same condition if the FDA concludes that the later product is clinically 
superior in that it is shown to be safer, more effective or makes a major contribution to patient care. Orphan drug exclusivity 
may also be lost if the FDA or EMA determines that the request for designation was materially defective or if the manufacturer 
is unable to assure sufficient quantity of the product to meet the needs of the patients with the rare disease or condition. In May 
2022, the FDA granted orphan drug designation to XMT-2056 for the treatment of patients with gastric cancer, and in 
December 2022, the European Commission granted orphan medicinal product designation to UpRi for the treatment of ovarian 
cancer, but we may not be able to obtain orphan drug exclusivity for any additional product candidates in the future. 

In 2017, Congress passed FDA Reauthorization Act of 2017, or FDARA. FDARA, among other things, codified the FDA’s pre-
existing regulatory interpretation, to require that a drug sponsor demonstrate the clinical superiority of an orphan drug that is 
otherwise the same as a previously approved drug for the same rare disease in order to receive orphan drug exclusivity. Under 
Omnibus legislation signed by President Trump on December 27, 2020, the requirement for a product to show clinical 
superiority applies to drugs and biologics that received orphan drug designation before enactment of FDARA in 2017 but have 
not yet been approved or licensed by the FDA. 

The FDA and Congress may further reevaluate the Orphan Drug Act and its regulations and policies. This may be particularly 
true in light of a decision from the Court of Appeals for the 11th Circuit in September 2021 finding that, for the purpose of 
determining the scope of exclusivity, the term “same disease or condition” means the designated “rare disease or condition” and 
could not be interpreted by the FDA to mean the “indication or use.” The court concluded that orphan drug exclusivity applies 
to the entire designated disease or condition rather than the “indication or use.” Although there have been legislative proposals 
to overrule this decision, they have not been enacted into law. On January 23, 2023, the FDA announced that, in matters beyond 
the scope of that court order, the FDA will continue to apply its existing regulations tying orphan-drug exclusivity to the uses or 
indications for which the orphan drug was approved. We do not know if, when, or how the FDA or Congress may change the 
orphan drug regulations and policies in the future, and it is uncertain how any changes might affect our business. Depending on 
what changes the FDA may make to its orphan drug regulations and policies, we may lose any expected benefits of the orphan 
drug designation we have received for XMT-2056, and our business could be adversely impacted. 

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Inadequate funding for the FDA, the SEC and other government agencies, including from government shut downs, or other 
disruptions to these agencies’ operations, could hinder their ability to hire and retain key leadership and other personnel, 
prevent new products and services from being developed or commercialized in a timely manner or otherwise prevent those 
agencies from performing normal business functions on which the operation of our business may rely, which could 
negatively impact our business. 

The ability of the FDA to review and approve new products can be affected by a variety of factors, including government 
budget and funding levels, ability to hire and retain key personnel and accept the payment of user fees, and statutory, regulatory 
and policy changes. Average review times at the agency have fluctuated in recent years as a result. Disruptions at the FDA and 
other agencies may also slow the time necessary for new product candidates to be reviewed and/or approved by necessary 
government agencies, which would adversely affect our business. In addition, government funding of the SEC and other 
government agencies on which our operations may rely, including those that fund research and development activities, is 
subject to the political process, which is inherently fluid and unpredictable. 

Disruptions at the FDA and other agencies may also slow the time necessary for new product candidates to be reviewed and/or 
approved by necessary government agencies, which would adversely affect our business. For example, over the last several 
years the U.S. government has shut down several times and certain regulatory agencies, such as the FDA and the SEC, have had 
to furlough critical FDA, SEC and other government employees and stop critical activities. If a prolonged government 
shutdown occurs, it could significantly impact the ability of the FDA to timely review and process our regulatory submissions, 
which could have a material adverse effect on our business. Further, future government shutdowns could impact our ability to 
access the public markets and obtain necessary capital in order to properly capitalize and continue our operations. 

Separately, in response to the COVID-19 pandemic, a number of companies announced receipt of complete response letters due 
to the FDA’s inability to complete required inspections for their applications. As of May 26, 2021, the FDA noted it was 
continuing to ensure timely reviews of applications for medical products during the ongoing COVID-19 pandemic in line with 
its user fee performance goals and conducting mission critical domestic and foreign inspections to ensure compliance of 
manufacturing facilities with FDA quality standards. However, the FDA may not be able to continue its current pace and review 
timelines could be extended, including where a pre-approval inspection or an inspection of clinical sites is required and due to 
the ongoing COVID-19 pandemic and travel restrictions, the FDA is unable to complete such required inspections during the 
review period. Regulatory authorities outside the United States may adopt similar restrictions or other policy measures in 
response to the COVID-19 pandemic and may experience delays in their regulatory activities.  

On January 30, 2023, the Biden Administration announced that it will end the public health emergency declarations related to 
COVID-19 on May 11, 2023. On January 31, 2023, the FDA indicated that it would soon issue a Federal Register notice 
describing how the termination of the public health emergency will impact the agency’s COVID-19 related guidance, including 
the clinical trial guidance and updates thereto. At this point, it is unclear how, if at all, these developments will impact our 
efforts to develop and commercialize our product candidates. If a prolonged government shutdown or other disruption occurs, it 
could significantly impact the ability of the FDA to timely review and process our regulatory submissions, which could have a 
material adverse effect on our business. Future shutdowns or other disruptions could also affect other government agencies such 
as the SEC, which may also impact our business by delaying review of our public filings, to the extent such review is necessary, 
and our ability to access the public markets. 

We are currently conducting clinical trials for UpRi, and may conduct future clinical trials for our other product candidates, 
at sites outside of the United States. The FDA may not accept data from trials conducted in such locations, or the complexity 
of regulatory burdens may otherwise adversely impact us. 

We are currently conducting clinical trials for UpRi outside of the United States, and we plan to continue to conduct clinical 
trials for UpRi and our current and future other product candidates outside of the United States. Although the FDA may accept 
data from clinical trials conducted outside the United States, acceptance of these data is subject to conditions imposed by the 
FDA. For example, the clinical trial must be well designed and conducted and be performed by qualified investigators in 
accordance with GCPs. If the foreign data is the sole basis for a marketing application, then the data must be applicable to the 
U.S. population and U.S. medical practice in ways that the FDA deems clinically meaningful and the FDA must be able to 
validate the data through an on-site inspection, if necessary. In addition, while these clinical trials are subject to the applicable 
local laws, FDA acceptance of the data will depend on its determination that the trials also complied with all applicable U.S. 
laws and regulations. If the FDA does not accept the data from any clinical trial that we conduct outside the United States, it 
would likely result in the need for additional clinical trials, which would be costly and time-consuming and could delay or 
permanently halt our development of the applicable product candidates. 

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Our ability to successfully initiate, enroll and complete a clinical trial in any country outside of the United States is subject to 
numerous additional risks unique to conducting business in jurisdictions outside the United States, including: 

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difficulty in establishing or managing relationships with qualified CROs, physicians and clinical trial sites; 

different local standards for the conduct of clinical trials; 

difficulty in complying with various and complex import laws and regulations when shipping drug to certain countries; 

the potential burden of complying with a variety of laws, medical standards and regulatory requirements, including the 
regulation of pharmaceutical and biotechnology products and treatments; 

lack of consistency in standard of care from country to country; 

diminished protection of intellectual property in some countries; 

foreign exchange fluctuations; 

cultural differences in medical practice and clinical research; and 

changes in country or regional regulatory requirements. 

Furthermore, the ongoing COVID-19 pandemic and the current conflict between Russia and Ukraine may also have an impact 
on our ability to successfully conduct trials outside of the United States. For example, we are conducting UPLIFT in countries 
where clinical trial site staff continue to be diverted to care for COVID-19 patients and where regulatory authorities are short 
staffed, due in part to continuing impacts of the COVID-19 pandemic. Additionally, we do business with a CRO that has had 
employees and operations in Ukraine that have been adversely impacted by Russian hostilities, though such employees and 
operations are not directly involved with our clinical trials. If we have difficulty conducting our clinical trials in jurisdictions 
outside the United States as planned, we may need to delay, limit or terminate ongoing or planned clinical trials, any of which 
could have a material adverse effect on our business. 

Accelerated approval by the FDA, even if granted for UpRi or any other current or future product candidates, may not lead 
to a faster development or regulatory review or approval process and it does not increase the likelihood that our product 
candidates will receive marketing approval. 

We intend to seek approval of UpRi and may seek approval any of our other current and future product candidates using the 
FDA’s accelerated approval pathway. A product may be eligible for accelerated approval if it treats a serious or life-threatening 
condition, generally provides a meaningful advantage over available therapies, and demonstrates an effect on a surrogate 
endpoint that is reasonably likely to predict clinical benefit. The FDA or other applicable regulatory agency makes the 
determination regarding whether a surrogate endpoint is reasonably likely to predict long-term clinical benefit. 

Prior to seeking such accelerated approval, we will seek feedback from the FDA and otherwise evaluate our ability to seek and 
receive such accelerated approval. As a condition of approval, the FDA requires that a sponsor of a product receiving 
accelerated approval perform an adequate and well-controlled post-marketing confirmatory clinical trial or trials. These 
confirmatory trials must be completed with due diligence and we may be required to evaluate different or additional endpoints 
in these post-marketing confirmatory trials. These confirmatory trials may require enrollment of more patients than we 
currently anticipate and will result in additional costs, which may be greater than the estimated costs we currently anticipate. In 
addition, the FDA currently requires as a condition for accelerated approval preapproval of promotional materials, which could 
adversely impact the timing of the commercial launch of the product. 

There can be no assurance that the FDA will agree with any proposed surrogate endpoints or that we will decide to pursue or 
submit an BLA for accelerated approval or any other form of expedited development, review or approval for UpRi or any of our 
other current or future product candidates. Similarly, there can be no assurance that, after feedback from FDA, we will continue 
to pursue or apply for accelerated approval or any other form of expedited development, review or approval, even if we initially 
decide to do so. Furthermore, if we decide to submit an application for accelerated approval or under another expedited 
regulatory designation, there can be no assurance that such submission or application will be accepted or that any expedited 
review or approval will be granted on a timely basis, or at all. 

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The FDA may withdraw approval of a product candidate approved under the accelerated approval pathway if, for example, the 
trial required to verify the predicted clinical benefit of our product candidate fails to verify such benefit or does not demonstrate 
sufficient clinical benefit to justify the risks associated with the drug. The FDA may also withdraw approval if other evidence 
demonstrates that our product candidate is not shown to be safe or effective under the conditions of use, we fail to conduct any 
required post approval trial of our product candidate with due diligence or we disseminate false or misleading promotional 
materials relating to our product candidate. A failure to obtain accelerated approval or any other form of expedited 
development, review or approval for our product candidates, or withdrawal of a product candidate, would result in a longer time 
period for commercialization of such product candidate, could increase the cost of development of such product candidate and 
could harm our competitive position in the marketplace. 

With passage of the Food and Drug Omnibus Reform Act, or FDORA, in December 2022, Congress modified certain 
provisions governing accelerated approval of drug and biologic products. Specifically, the new legislation authorized the FDA 
to: require a sponsor to have its confirmatory clinical trial underway before accelerated approval is awarded, require a sponsor 
of a product granted accelerated approval to submit progress reports on its post-approval studies to the FDA every six months 
until the study is completed; and use expedited procedures to withdraw accelerated approval of a new drug application or BLA 
after the confirmatory trial fails to verify the product’s clinical benefit. Further, FDORA requires the agency to publish on its 
website “the rationale for why a post-approval study is not appropriate or necessary” whenever it decides not to require such a 
study upon granting accelerated approval. 

Accordingly, even if we do receive accelerated approval, we may not experience a faster development or regulatory review or 
approval process, and receiving accelerated approval does not provide assurance of ultimate full FDA approval. 

If we or our third-party collaborators are unable to successfully develop and commercialize any required companion 
diagnostics or appropriate complementary diagnostics for our product candidates or to engage a third party to do so, or we 
or they experience significant delays in doing so, we may not realize the full potential of our product candidates. 

We expect that that a companion or complementary diagnostic may be necessary in connection with UpRi, and a companion or 
complementary diagnostic may be necessary in connection with any of our other current or future product candidates. If a 
companion diagnostic is required for the label of any of our product candidates, our ability to market such product candidates 
will be conditioned on the commercial availability of an approved companion diagnostic. Similarly, if a complementary 
diagnostic is necessary for any of our product candidates, we may not realize the full potential of such product candidates if 
such complementary diagnostic is not available. 

We may seek approval for any such companion diagnostic or complementary diagnostic, or we may contract with third parties 
to create and obtain approval for a companion or complementary diagnostic, including our NaPi2b assay. To be successful in 
developing and commercializing such a companion or complementary diagnostic, we need to address a number of scientific, 
technical and logistical challenges. We have little experience in the development and commercialization of companion or 
complementary diagnostics and may not be successful in developing and commercializing either our NaPi2b assay or any other 
appropriate companion or complementary diagnostics to pair with UpRi or any of our other current or future product 
candidates. Companion and complementary diagnostics are subject to regulation by the FDA and equivalent foreign regulatory 
authorities as medical devices and require separate regulatory approval prior to commercialization. Given our limited 
experience in developing diagnostics, we will rely in part or in whole on third parties for their design, manufacture and 
commercialization. We, our collaborators or such third parties may encounter difficulties in developing and obtaining approval 
for the companion or complementary diagnostics, including issues relating to selectivity/specificity, analytical validation, 
reproducibility or clinical validation. Any delay or failure by us, our collaborators or such third parties to develop or obtain 
regulatory approval of the companion or complementary diagnostics could delay or prevent approval or limit our ability to 
recognize the full potential of our product candidates. If we, or any third parties that we may contract with to assist us, are 
unable to successfully develop and commercialize companion or complementary diagnostics for our product candidates, or 
experience delays in doing so: 

• 

our product candidates may not receive marketing approval if safe and effective use of a product candidate depends on 
the availability of a companion diagnostic and such diagnostic is not commercially available or otherwise approved or 
cleared by the appropriate regulatory authority; and 

•  we may not realize the full commercial potential of any product candidates that receive marketing approval if, among 
other reasons, we are unable to appropriately select patients who are likely to benefit from therapy with our products, 
if approved. 

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If any of these events were to occur, our business would be harmed, possibly materially. 

In addition, third-party collaborators may encounter production difficulties that could constrain the supply of the companion or 
complementary diagnostics, and both they and we may have difficulties gaining acceptance of the use of the companion 
diagnostics or complementary in the clinical community. If such companion or complementary diagnostics fail to gain market 
acceptance, it would have an adverse effect on our ability to derive revenues from sales of our product candidates, if approved. 
In addition, any diagnostic company with whom we contract may decide to discontinue selling or manufacturing the companion 
diagnostic or complementary that we anticipate using in connection with development and commercialization of our product 
candidates or our relationship with such diagnostic company may otherwise terminate. Additionally, we may need to enter into 
contracts with more than one third party in order to gain widespread availability and acceptance of any companion or 
complementary diagnostic. We may not be able to enter into arrangements with another or additional diagnostic company to 
obtain supplies of additional or an alternative diagnostic test for use in connection with the development and commercialization 
of our product candidates or do so on commercially reasonable terms, which could adversely affect and/or delay the 
development or commercialization of our product candidates. 

Our activities, including our interactions with healthcare providers, third party payors, patients and government officials, 
are, and will continue to be, subject to extensive regulation involving health care, anti-corruption, data privacy and security 
and consumer protection laws. Failure to comply with applicable laws could result in substantial penalties, contractual 
damages, reputational harm, diminished revenues and curtailment or restructuring of our operations. 

Our activities may now or in the future be directly or indirectly subject to various federal and state laws related to health care, 
anti-corruption, data privacy and security consumer protection. If we obtain FDA approval for any of our product candidates 
and begin commercializing those products in the United States, our potential exposure under such laws will increase 
significantly, and our costs associated with compliance with such laws are also likely to increase. These laws include, but are 
not limited to: 

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federal false claims, false statements and civil monetary penalties laws prohibiting, among other things, any person 
from knowingly presenting, or causing to be presented, a false claim for payment of government funds or knowingly 
making, or causing to be made, a false statement to get a false claim paid; 

the federal anti-kickback law, which prohibits, among other things, persons from offering, soliciting, receiving or 
providing any remuneration, directly or indirectly, to induce, either the referral of an individual for, or the purchasing 
or ordering of a good or service, for which payment may be made under federal health care programs such as the 
Medicare and Medicaid; 

the federal anti-kickback prohibition known as Eliminating Kickbacks in Recovery Act, enacted in 2018, which 
prohibits certain payments related to referrals of patients to certain providers (recovery homes, clinical treatment 
facilities and laboratories) and applies to services reimbursed by private health plans as well as government health care 
programs; 

the federal law known as Health Insurance Portability and Accountability Act of 1996, or HIPAA, which, in addition to 
privacy protections to healthcare providers and other entities, prohibits executing a scheme to defraud any healthcare 
benefit program (which may include private health plans) or making false statements relating to healthcare matters; 

the Food, Drug, and Cosmetic Act, which among other things, strictly regulates drug marketing, prohibits 
manufacturers from marketing such products for off-label use and regulates the distribution of samples; 

federal laws that require pharmaceutical manufacturers to report certain calculated product prices to the government or 
provide certain discounts or rebates to government authorities or private entities, often as a condition of reimbursement 
under government healthcare programs; 

the so-called “federal sunshine” law, which requires pharmaceutical and medical device companies to monitor and 
report certain financial interactions with teaching hospitals, physicians and certain non-physician practitioners to the 
federal government for re-disclosure to the public; 

the privacy, security and breach provisions of HIPAA, which impose obligations on certain “covered entities” 
(healthcare providers, health plans and healthcare clearinghouses) and certain of their “business associate” contractors 
with respect to safeguarding the privacy, security and transmission of individually identifiable health information; 

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• 

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• 

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federal and state laws and regulations, including state security breach notification laws, state health information 
privacy laws, and federal and state consumer protection laws, govern the collection, use, disclosure and protection of 
health-related and other personal information. 

federal consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities 
that potentially harm consumers; 

the Foreign Corrupt Practices Act, or FCPA, a United States law which regulates certain financial relationships with 
foreign government officials (which could include, for example, certain medical professionals); and 

state law analogues of each of the above federal laws, such as anti-kickback and false claims laws which may apply to 
items or services reimbursed by any third-party payor, including private health plans, state privacy laws, state 
consumer protection laws, and state laws regulating interactions between pharmaceutical manufacturers and healthcare 
providers, requiring disclosure of such financial interactions or mandating adoption of certain compliance standards, 
many of which differ from each other in significant ways and often are not preempted by federal laws, thus 
complicating compliance efforts. 

In addition, the regulatory approval and commercialization of any of our product candidates outside the United States will also 
likely subject us to foreign equivalents of the health care laws mentioned above, among other foreign laws. Efforts to ensure 
that our business arrangements will comply with applicable health care laws may involve substantial costs. It is possible that 
governmental and enforcement authorities will conclude that our business practices may not comply with current or future 
statutes, regulations or case law interpreting applicable fraud and abuse or other health care laws and regulations. If our 
operations are found to be in violation of any of the laws described above or any other governmental regulations that apply to 
us, we may be subject to penalties, including, without limitation, civil, criminal and administrative penalties, damages, 
monetary fines, disgorgement, possible exclusion from participation in Medicare, Medicaid and other federal health care 
programs, contractual damages, reputational harm, diminished profits and future earnings and curtailment or restructuring of 
our operations. 

Current and future legislation may increase the difficulty and cost for us to obtain reimbursement for our product 
candidates. 

In the United States and some foreign jurisdictions, there have been and continue to be a number of legislative and regulatory 
changes and proposed changes regarding the healthcare system that could, among other things, prevent or delay marketing 
approval of our product candidates, restrict or regulate post-approval activities and affect our ability to profitably sell any 
products for which we obtain marketing approval. We expect that current laws, as well as other healthcare reform measures that 
may be adopted in the future, may result in more rigorous coverage criteria and in additional downward pressure on the price 
that we may receive for any approved products. If reimbursement of our products is unavailable or limited in scope, our 
business could be materially harmed. 

In March 2010, President Obama signed into law the Patient Protection and Affordable Care Act, as amended by the Health 
Care and Education Affordability Reconciliation Act, collectively the ACA. In addition, other legislative changes have been 
proposed and adopted since the ACA was enacted. In August 2011, the Budget Control Act of 2011, among other things, created 
measures for spending reductions by Congress. A Joint Select Committee on Deficit Reduction, tasked with recommending a 
targeted deficit reduction of at least $1.2 trillion for the years 2013 through 2021, was unable to reach required goals, thereby 
triggering the legislation’s automatic reduction to several government programs. These changes included aggregate reductions 
to Medicare payments to providers of up to 2% per fiscal year, which went into effect in April 2013 and will remain in effect 
through 2031 under the Coronavirus Aid, Relief, and Economic Security Act, or the CARES Act. These Medicare sequester 
reductions were suspended and reduced through the end of June 2022, with the full 2% cut resuming thereafter. The American 
Taxpayer Relief Act of 2012, among other things, reduced Medicare payments to several providers and increased the statute of 
limitations period for the government to recover overpayments to providers from three to five years. These laws may result in 
additional reductions in Medicare and other healthcare funding and otherwise affect the prices we may obtain for any of our 
products or product candidates for which we may obtain regulatory approval or the frequency with which any such product is 
prescribed or used. 

Since enactment of the ACA, there have been and continue to be, numerous legal challenges and Congressional actions to 
repeal and replace provisions of the law. For example, with enactment of the Tax Cuts for Jobs Act, or the Tax Act, in 2017, 
Congress repealed the “individual mandate.” The repeal of this provision, which requires most Americans to carry a minimal 
level of health insurance, became effective in 2019. Further, on December 14, 2018, a U.S. District Court judge in the Northern 
District of Texas ruled that the individual mandate portion of the ACA is an essential and inseverable feature of the ACA and 

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therefore because the mandate was repealed as part of the Tax Act, the remaining provisions of the ACA are invalid as well. The 
U.S. Supreme Court heard this case on November 10, 2020 and on June 17, 2021, dismissed this action after finding that the 
plaintiffs do not have standing to challenge the constitutionality of the ACA. Litigation and legislation over the ACA are likely 
to continue, with unpredictable and uncertain results. 

The Trump Administration also took executive actions to undermine or delay implementation of the ACA, including directing 
federal agencies with authorities and responsibilities under the ACA to waive, defer, grant exemptions from or delay the 
implementation of any provision of the ACA that would impose a fiscal or regulatory burden on states, individuals, healthcare 
providers, health insurers or manufacturers of pharmaceuticals or medical devices. On January 28, 2021, however, President 
Biden revoked those orders and issued a new Executive Order which directs federal agencies to reconsider rules and other 
policies that limit Americans’ access to health care and consider actions that will protect and strengthen that access. Under this 
order, federal agencies are directed to re-examine: policies that undermine protections for people with pre-existing conditions, 
including complications related to COVID-19; demonstrations and waivers under Medicaid and the ACA that may reduce 
coverage or undermine the programs, including work requirements; policies that undermine the Health Insurance Marketplace 
or other markets for health insurance; policies that make it more difficult to enroll in Medicaid and the ACA; and policies that 
reduce affordability of coverage or financial assistance, including for dependents. 

We expect that these healthcare reforms, as well as other healthcare reform measures that may be adopted in the future, may 
result in additional reductions in Medicare and other healthcare funding, more rigorous coverage criteria, new payment 
methodologies and additional downward pressure on the price that we receive for any approved product and/or the level of 
reimbursement physicians receive for administering any approved product we might bring to market. Reductions in 
reimbursement levels may negatively impact the prices we receive or the frequency with which our products are prescribed or 
administered. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction 
in payments from private payors. Accordingly, such reforms, if enacted, could have an adverse effect on anticipated revenue 
from product candidates that we may successfully develop and for which we may obtain marketing approval and may affect our 
overall financial condition and ability to develop or commercialize product candidates. 

The prices of prescription pharmaceuticals in the United States and foreign jurisdictions are subject to considerable 
legislative and executive actions and could impact the prices we obtain for our products, if and when licensed. 

The prices of prescription pharmaceuticals have also been the subject of considerable discussion in the United States. There 
have been several recent U.S. congressional inquiries, as well as proposed and enacted state and federal legislation designed to, 
among other things, bring more transparency to pharmaceutical pricing, review the relationship between pricing and 
manufacturer patient programs, and reduce the costs of pharmaceuticals under Medicare and Medicaid. In 2020, President 
Trump issued several executive orders intended to lower the costs of prescription products and certain provisions in these orders 
have been incorporated into regulations. These regulations include an interim final rule implementing a most favored nation 
model for prices that would tie Medicare Part B payments for certain physician-administered pharmaceuticals to the lowest 
price paid in other economically advanced countries, effective January 1, 2021. That rule, however, has been subject to a 
nationwide preliminary injunction and, on December 29, 2021, the Center for Medicare & Medicaid Services, or CMS, issued a 
final rule to rescind it. With issuance of this rule, CMS stated that it will explore all options to incorporate value into payments 
for Medicare Part B pharmaceuticals and improve beneficiaries' access to evidence-based care. 

In addition, in October 2020, HHS and the FDA published a final rule allowing states and other entities to develop a Section 
804 Importation Program, or SIP, to import certain prescription drugs from Canada into the United States. The final rule is 
currently the subject of ongoing litigation, but at least six states (Vermont, Colorado, Florida, Maine, New Mexico, and New 
Hampshire) have passed laws allowing for the importation of drugs from Canada with the intent of developing SIPs for review 
and approval by the FDA. Further, on November 20, 2020, HHS finalized a regulation removing safe harbor protection for 
price reductions from pharmaceutical manufacturers to plan sponsors under Part D, either directly or through pharmacy benefit 
managers, unless the price reduction is required by law. The implementation of the rule has been delayed by the Biden 
administration from January 1, 2022 to January 1, 2023 in response to ongoing litigation. The rule also creates a new safe 
harbor for price reductions reflected at the point-of-sale, as well as a new safe harbor for certain fixed fee arrangements 
between pharmacy benefit managers and manufacturers, the implementation of which have also been delayed by the Biden 
administration until January 1, 2023 in response to ongoing litigation. The rule also creates a new safe harbor for price 
reductions reflected at the point-of-sale, as well as a new safe harbor for certain fixed fee arrangements between pharmacy 
benefit managers and manufacturers, the implementation of which has been delayed under January 1, 2026, by the 
Infrastructure Investment and Jobs Act. 

On July 9, 2021, President Biden signed Executive Order 14063, which focuses on, among other things, the price of 
pharmaceuticals. The order directs the Department of Health and Human Services, or HHS, to create a plan within 45 days to 

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combat “excessive pricing of prescription pharmaceuticals and enhance domestic pharmaceutical supply chains, to reduce the 
prices paid by the federal government for such pharmaceuticals, and to address the recurrent problem of price gouging.” On 
September 9, 2021, HHS released its plan to reduce pharmaceutical prices. The key features of that plan are to: (a) make 
pharmaceutical prices more affordable and equitable for all consumers and throughout the health care system by supporting 
pharmaceutical price negotiations with manufacturers; (b) improve and promote competition throughout the prescription 
pharmaceutical industry by supporting market changes that strengthen supply chains, promote biosimilars and generic drugs, 
and increase transparency; and (c) foster scientific innovation to promote better healthcare and improve health by supporting 
public and private research and making sure that market incentives promote discovery of valuable and accessible new 
treatments. 

More recently, on August 16, 2022, the Inflation Reduction Act of 2022, or IRA, was signed into law by President Biden. The 
new legislation has implications for Medicare Part D, which is a program available to individuals who are entitled to Medicare 
Part A or enrolled in Medicare Part B to  give them the option of paying  a  monthly premium for outpatient prescription drug 
coverage. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare 
(beginning in 2026), with prices that can be negotiated subject to a cap; imposes rebates under Medicare Part B and Medicare 
Part  D  to  penalize  price  increases  that  outpace  inflation  (first  due  in  2023);  and  replaces  the  Part  D  coverage  gap  discount 
program with a new discounting program (beginning in 2025). The IRA permits the Secretary of the Department of Health and 
Human  Service,  or  HHS,  to  implement  many  of  these  provisions  through  guidance,  as  opposed  to  regulation,  for  the  initial 
years. 

Specifically,  with  respect  to  price  negotiations,  Congress  authorized  Medicare  to  negotiate  lower  prices  for  certain  costly 
single-source drug and biologic products that do not have competing generics or biosimilars and are reimbursed under Medicare 
Part B and Part D. CMS may negotiate prices for ten high-cost drugs paid for by Medicare Part D starting in 2026, followed by 
15  additional  Medicare  Part  D  drugs  in  2027,  15  additional  Medicare  Part  B  or  Part  D  drugs  in  2028,  and  20  additional 
Medicare Part B or Part D drugs per year in 2029 and beyond. This provision applies to drug products that have been approved 
for at least nine years and biologics that have been licensed for 13 years, but it does not apply to drugs and biologics that have 
been  approved  for  a  single  rare  disease  or  condition.  Nonetheless,  since  CMS  may  establish  a  maximum  price  for  these 
products in price negotiations, we would be fully at risk of government action if our products are the subject of Medicare price 
negotiations. Moreover, given the risk that could be the case, these provisions of the IRA may also further heighten the risk that 
we  would  not  be  able  to  achieve  the  expected  return  on  any  of  our  product  candidates,  if  approved,  or  the full  value  of  our 
patents protecting any such approved drug products if prices are set after any such approved products have been on the market 
for nine years.  

Further, the legislation subjects drug manufacturers to civil monetary penalties and a potential excise tax for failing to comply 
with the legislation by offering a price that is not equal to or less than the negotiated “maximum fair price” under the law or for 
taking price increases that exceed inflation. The legislation also requires manufacturers to pay rebates for drugs in Medicare 
Part D whose price increases exceed inflation. The new law also caps Medicare out-of-pocket drug costs at an estimated $4,000 
a year in 2024 and, thereafter beginning in 2025, at $2,000 a year. In addition, the IRA potentially raises legal risks with respect 
to individuals participating in a Medicare Part D prescription drug plan who may experience a gap in coverage if they required 
coverage above their initial annual coverage limit before they reached the higher threshold, or “catastrophic period” of the plan. 
Individuals requiring services exceeding the initial annual coverage limit and below the catastrophic period, must pay 100% of 
the cost of their prescriptions until they reach the catastrophic period. Among other things, the IRA contains many provisions 
aimed at reducing this financial burden on individuals by reducing the co-insurance and co-payment costs, expanding eligibility 
for lower income subsidy plans, and price caps on annual out-of-pocket expenses, each of which could have potential pricing 
and reporting implications. Accordingly, while it is currently unclear how the IRA will be effectuated, we cannot predict with 
certainty what impact any federal or state health reforms will have on us, but such changes could impose new or more stringent 
regulatory requirements on our activities or result in reduced reimbursement for our products, any of which could adversely 
affect our business, results of operations and financial condition. 

At the state level, individual states are increasingly aggressive in passing legislation and implementing regulations designed to 
control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, 
restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to 
encourage importation from other countries and bulk purchasing. In addition, regional healthcare organizations and individual 
hospitals are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers will be 
included in their prescription drug and other healthcare programs. These measures could reduce the ultimate demand for our 
products, once approved, or put pressure on our product pricing. We expect that additional state and federal healthcare reform 
measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for 
healthcare products and services, which could result in reduced demand for our product candidates or additional pricing 
pressures. 

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In the European Union, similar political, economic and regulatory developments may affect our ability to profitably 
commercialize our product candidates, if approved. In markets outside of the United States and the European Union, 
reimbursement and healthcare payment systems vary significantly by country and many countries have instituted price ceilings 
on specific products and therapies. In many countries, including those of the European Union, the pricing of prescription 
pharmaceuticals is subject to governmental control and access. In these countries, pricing negotiations with governmental 
authorities can take considerable time after the receipt of marketing approval for a product. To obtain reimbursement or pricing 
approval in some countries, we or our collaborators may be required to conduct a clinical trial that compares the cost-
effectiveness of our product to other available therapies. If reimbursement of our products is unavailable or limited in scope or 
amount or if pricing is set at unsatisfactory levels, our business could be materially harmed. 

We are subject to stringent privacy laws, information security laws, regulations, policies and contractual obligations related 
to data privacy and security, and a failure to comply with such requirements could subject us to significant fines and 
penalties, which may have a material adverse effect on our business, financial condition or results of operations. 

We are subject to data privacy and protection laws and regulations that apply to the collection, transmission, storage and use of 
personally-identifying information, which among other things, impose certain requirements relating to the privacy, security and 
transmission of personal information, including comprehensive regulatory systems in the United States, European Union and 
United Kingdom. The legislative and regulatory landscape for privacy and data protection continues to evolve in jurisdictions 
worldwide, and there has been an increasing focus on privacy and data protection issues with the potential to affect our 
business. Failure to comply with any of these laws and regulations could result in enforcement action against us, including 
fines, imprisonment of company officials and public censure, claims for damages by affected individuals, damage to our 
reputation and loss of goodwill, any of which could have a material adverse effect on our business, financial condition, results 
of operations or prospects. 

There are numerous U.S. federal and state laws and regulations related to the privacy and security of personal information. In 
particular, regulations promulgated pursuant to HIPAA establish privacy and security standards that limit the use and disclosure 
of individually identifiable health information, or protected health information, and require the implementation of 
administrative, physical and technological safeguards to protect the privacy of protected health information and ensure the 
confidentiality, integrity and availability of electronic protected health information. Determining whether protected health 
information has been handled in compliance with applicable privacy standards and our contractual obligations can be complex 
and may be subject to changing interpretation. These obligations may be applicable to some or all of our business activities now 
or in the future. 

If we are unable to properly protect the privacy and security of protected health information, we could be found to have 
breached our contracts. Further, if we fail to comply with applicable privacy laws, including applicable HIPAA privacy and 
security standards, we could face civil and criminal penalties. HHS enforcement activity can result in financial liability and 
reputational harm, and responses to such enforcement activity can consume significant internal resources. In addition, state 
attorneys general are authorized to bring civil actions seeking either injunctions or damages in response to violations that 
threaten the privacy of state residents. We cannot be sure how these regulations will be interpreted, enforced or applied to our 
operations. In addition to the risks associated with enforcement activities and potential contractual liabilities, our ongoing 
efforts to comply with evolving laws and regulations at the federal and state level may be costly and require ongoing 
modifications to our policies, procedures and systems. 

Similar to the laws in the United States, there are significant privacy and data security laws that apply in Europe and other 
countries. The collection, use, disclosure, transfer, or other processing of personal data, including personal health data, 
regarding individuals who are located in the European Economic Area, or the EEA, and the processing of personal data that 
takes place in the EEA, is regulated by the General Data Protection Regulation, or GDPR, which went into effect in May 2018 
and which imposes obligations on companies that operate in our industry with respect to the processing of personal data and the 
cross-border transfer of such data. The GDPR imposes onerous accountability obligations requiring data controllers and 
processors to maintain a record of their data processing and policies. If our or our collaborators’ or service providers’ privacy or 
data security measures fail to comply with the GDPR requirements, we may be subject to litigation, regulatory investigations, 
enforcement notices requiring us to change the way we use personal data and/or fines of up to 20 million Euros or up to 4% of 
the total worldwide annual turnover of the preceding financial year, whichever is higher, as well as compensation claims by 
affected individuals, negative publicity, reputational harm and a potential loss of business and goodwill. 

The GDPR places restrictions on the cross-border transfer of personal data from the European Union to countries that have not 
been found by the European Commission to offer adequate data protection legislation, such as the United States. There are 
ongoing concerns about the ability of companies to transfer personal data from the European Union to other countries. In July 

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2020, the Court of Justice of the European Union, or the CJEU, invalidated the EU-U.S. Privacy Shield, one of the mechanisms 
used to legitimize the transfer of personal data from the EEA to the United States. The CJEU decision also drew into question 
the long-term viability of an alternative means of data transfer, the standard contractual clauses, for transfers of personal data 
from the EEA to the United States. While we were not self-certified under the Privacy Shield, this CJEU decision may lead to 
increased scrutiny on data transfers from the EEA to the United States generally and increase our costs of compliance with data 
privacy legislation as well as our costs of negotiating appropriate privacy and security agreements with our vendors and 
business partners. 

Laws and regulations governing any international operations we may have in the future may preclude us from developing, 
manufacturing and selling certain products outside of the United States and require us to develop and implement costly 
compliance programs. 

If we further expand our operations outside the United States, we will need to dedicate additional resources to comply with U.S. 
laws regarding international operations and the laws and regulations in each jurisdiction in which we operate and plan to 
operate. The FCPA prohibits any U.S. individual or business from paying, offering or authorizing payment or offering of 
anything of value, directly or indirectly, to any foreign official, political party or candidate for the purpose of influencing any 
act or decision of the foreign entity in order to assist the individual or business in obtaining or retaining business. The FCPA 
also obligates companies whose securities are listed in the United States to comply with certain accounting provisions requiring 
the company to maintain books and records that accurately and fairly reflect all transactions of the company, including 
international subsidiaries and to devise and maintain an adequate system of internal accounting controls for international 
operations. 

Compliance with the FCPA is expensive and difficult, particularly in countries in which corruption is a recognized problem. In 
addition, the FCPA presents particular challenges in the pharmaceutical industry because in many countries, hospitals are 
operated by the government and doctors and other hospital employees are considered foreign officials. Certain payments to 
hospitals in connection with clinical trials and other work have been deemed to be improper payments to government officials 
and have led to FCPA enforcement actions. 

Various laws, regulations and executive orders also restrict the use and dissemination outside of the United States or the sharing 
with certain non-U.S. nationals, of information classified for national security purposes, as well as certain products and 
technical data relating to those products. Further, the provision of benefits or advantages to physicians to induce or encourage 
the prescription, recommendation, endorsement, purchase, supply, order or use of medicinal products is prohibited in the 
European Union. The provision of benefits or advantages to physicians is also governed by the national anti-bribery laws of 
E.U. Member States, such as the U.K. Bribery Act 2010. Infringement of these laws could result in substantial fines and 
imprisonment. Payments made to physicians in certain E.U. Member States must be publicly disclosed. Moreover, agreements 
with physicians often must be the subject of prior notification and approval by the physician’s employer, his or her competent 
professional organization and/or the regulatory authorities of the individual E.U. Member States. These requirements are 
provided in the national laws, industry codes or professional codes of conduct applicable in the E.U. Member States. Failure to 
comply with these requirements could result in reputational risk, public reprimands, administrative penalties, fines or 
imprisonment. 

If we expand our presence outside of the United States , it will require us to dedicate additional resources to comply with these 
laws and these laws may preclude us from developing, manufacturing or selling certain products and product candidates outside 
of the United States, which could limit our growth potential and increase our development costs. The failure to comply with 
laws governing international business practices may result in substantial civil and criminal penalties and suspension or 
debarment from government contracting. The SEC also may suspend or bar issuers from trading securities on U.S. exchanges 
for violations of the FCPA’s accounting provisions. 

We and our third-party contract manufacturers must comply with environmental, health and safety laws and regulations, 
and failure to comply with these laws and regulations could expose us to significant costs or liabilities. 

We and our third-party manufacturers are subject to numerous environmental, health and safety laws and regulations, including 
those governing laboratory procedures and the use, generation, manufacture, distribution, storage, handling, treatment, 
remediation and disposal of hazardous materials and wastes. Hazardous chemicals, including flammable and biological 
materials, are involved in certain aspects of our business, and we cannot eliminate the risk of injury or contamination from the 
use, generation, manufacture, distribution, storage, handling, treatment or disposal of hazardous materials and wastes. In the 
event of contamination or injury, or failure to comply with environmental, health and safety laws and regulations, we could be 
held liable for any resulting damages and any such liability could exceed our assets and resources. We could also incur 
significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations. 

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Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our 
employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential 
liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in 
connection with our storage or disposal of biological, hazardous or radioactive materials. 

Environmental, health and safety laws and regulations are becoming increasingly more stringent. We may incur substantial 
costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future 
laws and regulations may impair our research, development or production efforts. Our failure to comply with these laws and 
regulations also may result in substantial fines, penalties or other sanctions. 

Further, with respect to the operations of our third-party contract manufacturers, it is possible that if they fail to operate in 
compliance with applicable environmental, health and safety laws and regulations or properly dispose of wastes associated with 
our products, we could be held liable for any resulting damages, suffer reputational harm or experience a disruption in the 
manufacture and supply of our product candidates or products. 

Our employees may engage in misconduct or other improper activities, including noncompliance with regulatory standards 
and requirements and insider trading. 

We are exposed to the risk of employee fraud or other misconduct. Misconduct by employees could include intentional failures 
to comply with FDA regulations, to provide accurate information to the FDA, to comply with manufacturing standards we have 
established, to comply with federal and state healthcare fraud and abuse laws and regulations, to report financial information or 
data accurately or to disclose unauthorized activities to us. In particular, sales, marketing and business arrangements in the 
healthcare industry are subject to extensive laws and regulations intended to prevent fraud, kickbacks, self-dealing and other 
abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and 
promotion, sales commission, customer incentive programs and other business arrangements. Employee misconduct could also 
involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and 
serious harm to our reputation. It is not always possible to identify and deter employee misconduct, and the precautions we take 
to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us 
from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws or 
regulations. Additionally, we are subject to the risk that a person could allege such fraud or other misconduct, even if none 
occurred. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, 
those actions could have a significant impact on our business, including the imposition of civil, criminal and administrative 
penalties, damages, monetary fines, disgorgement, possible exclusion from participation in Medicare, Medicaid and other 
federal health care programs, contractual damages, reputational harm, diminished profits and future earnings and curtailment or 
restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of 
operations. 

Risks Related to our Business and Industry 

If we fail to attract and retain senior management and key scientific personnel, we may be unable to successfully develop 
our ADC product candidates, conduct our clinical trials and commercialize our ADC product candidates. 

Our ability to compete in the highly competitive biotechnology and biopharmaceutical industries depends upon our ability to 
attract, motivate and retain highly qualified managerial, scientific and medical personnel. We are highly dependent on members 
of our senior management, including Anna Protopapas, our President and Chief Executive Officer. The loss of the services of 
any of our senior management could impede the achievement of our research, development and commercialization objectives. 
Also, each of these persons may terminate their employment with us at any time. We do not maintain “key person” insurance 
for any of our executives or other employees. 

Recruiting and retaining qualified scientific, clinical, sales and marketing personnel will also be critical to our success. We 
conduct our operations at our facility in Cambridge, Massachusetts, in a region that is headquarters to many other 
biopharmaceutical companies and many academic and research institutions. Competition for skilled personnel is intense and the 
turnover rate can be high, which may limit our ability to hire and retain highly qualified personnel on acceptable terms or at all. 
We may not be able to attract and retain these personnel on acceptable terms given the competition among numerous 
pharmaceutical and biotechnology companies for similar personnel. In addition, we rely on consultants and advisors, including 
scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy. Our 
consultants and advisors may be employed or have commitments under consulting or advisory contracts with other entities that 
may limit their availability to us. 

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We may encounter difficulties in managing our growth and expanding our operations successfully. 

As we seek to advance our product candidates through clinical trials and commercialization, we will need to expand our 
development, regulatory, manufacturing, marketing and sales capabilities or contract with third parties to provide these 
capabilities for us. As our operations expand, we have needed to and expect that we will continue to need to manage additional 
relationships with various strategic collaborators, suppliers and other third parties. Future growth will impose significant added 
responsibilities on members of management. Our future financial performance and our ability to commercialize our product 
candidates and to compete effectively will depend, in part, on our ability to manage any future growth effectively. To that end, 
we must be able to manage our development efforts and clinical trials effectively and hire, train and integrate additional 
management, administrative and, if necessary, sales and marketing personnel. Due to our limited financial resources and the 
limited experience of our management team in managing a company with such anticipated growth, we may not be able to 
accomplish these tasks, and our failure to accomplish any of them could prevent us from successfully growing our company or 
disrupt our operations. 

If product liability lawsuits are brought against us, we may incur substantial liabilities and may be required to limit 
commercialization of our ADC product candidates. 

We face an inherent risk of product liability as a result of the clinical testing of our product candidates and will face an even 
greater risk if we commercialize any products. For example, we may be sued if any product we develop causes, or is perceived 
to cause, injury or is found to be otherwise unsuitable during clinical testing, manufacturing, marketing or sale. Any such 
product liability claims may include allegations of defects in manufacturing, defects in design, a failure to warn of dangers 
inherent in the product, negligence, strict liability and a breach of warranties. Claims could also be asserted under state 
consumer protection acts. If we cannot successfully defend ourselves against product liability claims, we may incur substantial 
liabilities or be required to limit commercialization of our product candidates. Even a successful defense would require 
significant financial and management resources. Regardless of the merits or eventual outcome, liability claims may result in: 

• 

• 

injury to our reputation; 

decreased demand for our product candidates or products that we may develop; 

•  withdrawal of clinical trial participants; 

• 

• 

• 

• 

• 

• 

• 

costs to defend the related litigations; 

a diversion of management’s time and our resources; 

substantial monetary awards to clinical trial participants or patients; 

product recalls, withdrawals or labeling, marketing or promotional restrictions; 

loss of revenue; 

the inability to commercialize our product candidates; and 

a decline in our stock price. 

Failure to obtain and retain sufficient product liability insurance at an acceptable cost to protect against potential product 
liability claims could prevent or inhibit the commercialization of products we develop. We currently carry product liability 
insurance covering our clinical trials in the amount of $10 million in the aggregate. Although we maintain such insurance, any 
claim that may be brought against us could result in a court judgment or settlement in an amount that is not covered, in whole or 
in part, by our insurance or that is in excess of the limits of our insurance coverage. Our insurance policies also have various 
exclusions, and we may be subject to a product liability claim for which we have no coverage. In such instance, we might have 
to pay any amounts awarded by a court or negotiated in a settlement that exceed our coverage limitations or that are not covered 
by our insurance, and we may not have, or be able to obtain, sufficient capital to pay such amounts. If we are unable to obtain 
or maintain sufficient insurance coverage at an acceptable cost or to otherwise protect against potential product liability claims, 
it could prevent or inhibit the development and commercial production and sale of our product candidates, which could 
adversely affect our business, financial condition, results of operations and prospects. 

We may acquire assets or form strategic alliances in the future, and we may not realize the benefits of such acquisitions. 

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We may acquire additional technologies and assets, form strategic alliances or create joint ventures with third parties that we 
believe will complement or augment our existing business. If we acquire assets with promising markets or technologies, we 
may not be able to realize the benefit of acquiring such assets if we are unable to successfully integrate them with our existing 
technologies. We may encounter numerous difficulties in developing, manufacturing and marketing any new products resulting 
from a strategic alliance or acquisition that delay or prevent us from realizing their expected benefits or enhancing our business. 
We cannot be assured that, following any such acquisition, we will achieve the expected synergies to justify the transaction. Our 
internal computer systems, or those of our strategic and other third-party collaborators or other contractors or consultants, may 
fail or suffer security breaches, which could adversely affect our business, including through material disruptions of our 
programs or business operations. 

Our internal information technology systems and those of our current or future strategic and other third-party collaborators and 
other contractors and consultants are vulnerable to service interruptions or security breaches, including from cyber-attacks, 
computer viruses, ransomware, malware, unauthorized access, natural disasters, terrorism, war and telecommunication and 
electrical failures. If a failure, accident or security breach were to occur and cause interruptions in our operations or the 
operations of those third parties with which we contract, it could result in a material disruption of our programs and our 
business operations. We could lose access to our trade secrets or other proprietary information or experience other disruptions, 
which could require a substantial expenditure of resources to remedy. For example, the loss of clinical trial data for our product 
candidates could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce 
the data. 

We could also be subject to risks caused by misappropriation, misuse, leakage, falsification or intentional or accidental release 
or loss of information maintained in our information systems and networks, including personal information of our employees or 
others. Outside parties may attempt to penetrate our systems or those of the third parties with which we contract or to coerce or 
fraudulently induce our employees or employees of such third parties to disclose sensitive information to gain access to our 
data. The number and complexity of these threats continue to increase over time. Although we develop and maintain systems 
and controls designed to prevent these events from occurring, and we have a process to identify and mitigate threats, such risks 
cannot be eliminated. Furthermore, there can be no assurance that we, or those third parties with which we contract, will 
promptly detect any such disruption or security breach, if at all. Additionally, the development and maintenance of these 
systems, controls and processes is costly and requires ongoing monitoring and updating as technologies change and efforts to 
overcome security measures become more sophisticated. To the extent that any disruption or security breach results in a loss of 
or damage to our data or applications or other data or applications relating to our technology or product candidates, or 
inappropriate disclosure of confidential or proprietary information, we could incur liabilities, our competitive position and the 
market perception of the effectiveness of our security measures could be harmed, our credibility could be damaged and the 
further development of our product candidates could be delayed. 

Risks Related to Our Common Stock 

If our stock price is volatile, our stockholders could incur substantial losses. 

Our stock price has been and may continue to be volatile. During the period from February 24, 2020 to February 24, 2023, the 
closing  price  of our  common stock ranged from a  high of $27.59 per  share to  a  low of $2.84 per share. The market price of 
shares of our common stock could be subject to wide fluctuations in response to many risk factors listed in this “Risk Factors” 
section, and others beyond our control, including: 

• 

• 

• 

• 

• 

• 

• 

results and timing of preclinical studies and clinical trials of our current or future product candidates, including UpRi, 
XMT-1660 and XMT-2056; 

results of clinical trials of our competitors’ products; 

failure to adequately protect our trade secrets; 

the terms on which we raise additional capital or our ability to raise it; 

commencement or termination of any strategic collaboration or licensing arrangement; 

regulatory developments, including actions with respect to our products or our competitors’ products; 

actual or anticipated fluctuations in our financial condition and operating results; 

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• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

publication of research reports by securities analysts about us or our competitors or our industry; 

our failure or the failure of our competitors to meet analysts’ projections or guidance that we or our competitors may 
give to the market; 

additions and departures of key personnel; 

strategic decisions by us or our competitors, such as acquisitions, divestitures, spin-offs, joint ventures, strategic 
investments or changes in business strategy; 

the passage of legislation or other regulatory developments affecting us or our industry; 

changes in the structure of healthcare payment systems; 

fluctuations in the valuation of companies perceived by investors to be comparable to us; 

sales of our common stock by us (including pursuant to outstanding warrants or through our ATM offering programs), 
our insiders or our other stockholders; 

speculation in the press or investment community; 

announcement or expectation of additional financing efforts; 

changes in market conditions for biopharmaceutical stocks; and 

changes in general market and economic conditions. 

In addition, the stock market has historically experienced significant volatility, particularly with respect to pharmaceutical, 
biotechnology and other life sciences company stocks. The volatility of pharmaceutical, biotechnology and other life sciences 
company stocks often does not relate to the operating performance of the companies represented by the stock. As a result of this 
volatility, stockholders may not be able to sell their common stock at or above the price for which they paid for their shares. As 
we operate in a single industry, we are especially vulnerable to these factors to the extent that they affect our industry or our 
products, or to a lesser extent our markets. Furthermore, as a result of this volatility, we may not be able to maintain compliance 
with listing requirements of the Nasdaq Stock Market. In the past, securities class action litigation has often been initiated 
against companies following periods of volatility in their stock price. This type of litigation could result in substantial costs and 
divert our management’s attention and resources, and could also require us to make substantial payments to satisfy judgments 
or to settle litigation. 

We do not expect to pay any cash dividends for the foreseeable future. 

We do not anticipate that we will pay any cash dividends to holders of our common stock in the foreseeable future. Instead, we 
plan to retain any earnings to maintain and expand our operations. In addition, our New Credit Facility contains terms and any 
future debt financing arrangement may contain additional terms prohibiting or limiting the amount of dividends that may be 
declared or paid on our common stock. Accordingly, investors must rely on sales of their common stock after price 
appreciation, which may never occur, as the only way to realize any return on their investment. 

Provisions in our amended and restated certificate of incorporation, as amended, our amended and restated by-laws and 
Delaware law may have anti-takeover effects that could discourage an acquisition of us by others, even if an acquisition 
would be beneficial to our stockholders, and may prevent attempts by our stockholders to replace or remove our current 
management. 

Our amended and restated certificate of incorporation, as amended, amended and restated by-laws and Delaware law contain 
provisions that may have the effect of discouraging, delaying or preventing a change in control of us or changes in our 
management that stockholders may consider favorable, including transactions in which our stockholders might otherwise 
receive a premium for their shares. Our amended and restated certificate of incorporation, as amended, and amended and 
restated by-laws include provisions that: 

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• 

• 

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• 

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• 

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• 

authorize “blank check” preferred stock, which could be issued by our board of directors without stockholder approval 
and may contain voting, liquidation, dividend and other rights superior to our common stock; 

create a classified board of directors whose members serve staggered three-year terms; 

specify that special meetings of our stockholders can be called only by our board of directors; 

prohibit stockholder action by written consent; 

establish an advance notice procedure for stockholder approvals to be brought before an annual meeting of our 
stockholders, including proposed nominations of persons for election to our board of directors; 

provide that vacancies on our board of directors may be filled only by a majority of directors then in office, even 
though less than a quorum; 

provide that our directors may be removed only for cause; 

specify that no stockholder is permitted to cumulate votes at any election of directors; 

expressly authorize our board of directors to have discretion to modify, alter or repeal our amended and restated by-
laws; and 

require supermajority votes of the holders of our common stock to amend specified provisions of our amended and 
restated certificate of incorporation, as amended, and amended and restated by-laws. 

In addition, because we are incorporated in the State of Delaware, we are governed by the provisions of Section 203 of the 
General Corporation Law of the State of Delaware, or the DGCL, which prohibits a person who owns in excess of 15% of our 
outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in 
which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a 
prescribed manner. 

Any provision of our amended and restated certificate of incorporation, as amended, amended and restated by-laws or Delaware 
law that has the effect of delaying or deterring a change in control could limit the opportunity for our stockholders to receive a 
premium for their shares of our common stock, and could also affect the price that some investors are willing to pay for our 
common stock. 

Our ability to use net operating losses and certain tax credit carryforwards may be subject to certain limitations. 

For the years ended December 31, 2022, 2021 and 2020, we recorded no income tax benefit for the net operating losses, or 
NOLs, incurred in each year, due to the uncertainty of realizing a benefit from those items. We have incurred NOLs since our 
inception. As of December 31, 2022 , we have federal NOLs of approximately $432.8 million and state NOLs of approximately 
$365.3 million. Of the $432.8 million of federal NOLs, $34.1 million expire at various dates through 2037. The remaining 
$398.7 million of federal NOLs do not expire. The state NOLs will expire at various dates through 2042. As of December 31, 
2022, we had federal and state research and development tax credit carryforwards of approximately $17.4 million and $5.1 
million, respectively, which expire at various dates through 2042. Under the Tax Act, federal NOLs incurred in 2018 and in 
future years may be carried forward indefinitely, but the deductibility of such federal NOLs is limited. It is uncertain if and to 
what extent various states will conform to the Tax Act. In addition, under Section 382 of the Internal Revenue Code, or the 
Code, and corresponding provisions of state law, if a corporation undergoes an “ownership change,” which is generally defined 
as a greater than 50% change, by value, in its equity ownership over a three-year period, the corporation’s ability to use its pre-
change NOLs and other pre-change tax attributes to offset its post-change income or taxes may be limited. Our past issuances 
of stock and other changes in our stock ownership may have resulted in ownership changes within the meaning of Section 382 
of the Code; accordingly, our pre-change NOLs may be subject to limitation under Section 382. If we determine that we have 
not undergone an ownership change, the Internal Revenue Service could challenge our analysis, and our ability to use our 
NOLs to offset taxable income could be limited by Section 382 of the Code. Future changes in our stock ownership, some of 
which are outside of our control, could result in ownership changes under Section 382 of the Code further limiting our ability to 
utilize our NOLs. Our NOLs may also be impaired under state law. Accordingly, we may not be able to utilize a material 
portion of our NOLs. We have determined that ownership changes have occurred since our inception and that certain NOLs and 
research and development tax credit carryforwards will be subject to limitation. We may also have incurred subsequent 
ownership changes. Furthermore, our ability to utilize our NOLs and research and development tax credit carryforwards is 

84 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
conditioned upon our attaining profitability and generating U.S. federal taxable income. We have incurred net losses since our 
inception and anticipate that we will continue to incur significant losses for at least the next several years; thus, we do not know 
when we will generate the U.S. federal taxable income necessary to utilize our NOLs. We have recorded a full valuation 
allowance related to our NOLs and other deferred tax assets due to the uncertainty of the ultimate realization of the future 
benefits of those assets. 

Changes in tax laws or in their implementation or interpretation may adversely affect our business and financial condition. 

Changes in tax law may adversely affect our business or financial condition. The Tax Act, as amended by the CARES Act, 
significantly revises the Code. The Tax Act, among other things, contains significant changes to corporate taxation, including 
reduction of the corporate tax rate from a top marginal rate of 35% to a flat rate of 21% and limitation of the deduction for 
NOLs to 80% of current year taxable income for losses arising in taxable years beginning after December 31, 2017, though any 
such NOLs may be carried forward indefinitely. In addition, beginning in 2022, the Tax Act eliminates the option to deduct 
research and development expenditures currently and requires corporations to capitalize and amortize them over five years. 

In addition to the CARES Act, as part of Congress’ response to the COVID-19 pandemic, economic relief legislation was 
enacted in 2020 and 2021 containing tax provisions. The IRA, which was signed into law in August 2022, also introduced new 
tax provisions, including a one percent excise tax imposed on certain stock repurchases by publicly traded corporations. The 
one percent excise tax generally applies to any acquisition of stock by the publicly traded corporation (or certain of its affiliates) 
from a stockholder of the corporation in exchange for money or other property (other than stock of the corporation itself), 
subject to a de minimis exception. Thus, the excise tax could apply to certain transactions that are not traditional stock 
repurchases. 

Regulatory guidance under the Tax Act, the IRA, and additional legislation is and continues to be forthcoming, and such 
guidance could ultimately increase or lessen their impact on our business and financial condition. In addition, it is uncertain if 
and to what extent various states will conform to the Tax Act, the IRA, and additional tax legislation. 

Our amended and restated certificate of incorporation, as amended, designates the state or federal courts within the State of 
Delaware as the exclusive forum for certain types of actions and proceedings that may be initiated by our stockholders, 
which could limit our stockholders’ ability to obtain a favorable judicial forum for disputes with us or our directors, officers 
or employees. 

Our amended and restated certificate of incorporation, as amended, provides that, subject to limited exceptions, the Court of 
Chancery of the State of Delaware will be the exclusive forum for (1) any derivative action or proceeding brought on our 
behalf, (2) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or other employees 
to us or our stockholders, (3) any action asserting a claim against us arising pursuant to any provision of the DGCL, our 
amended and restated certificate of incorporation, as amended, or our amended and restated by-laws, (4) any action to interpret, 
apply, enforce or determine the validity of our amended and restated certificate of incorporation, as amended, or amended and 
restated by-laws or (5) any other action asserting a claim against us that is governed by the internal affairs doctrine, in each case 
subject to the Court of Chancery having personal jurisdiction over the indispensable parties named as defendants therein. Any 
person or entity that purchases or otherwise acquires any interest in shares of our capital stock shall be deemed to have notice of 
and to have consented to the provisions of our amended and restated certificate of incorporation, as amended, described above. 
This choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for 
disputes with us or our directors, officers or other employees, which may discourage such lawsuits against us and our directors, 
officers and employees. Alternatively, if a court were to find these provisions of our amended and restated certificate of 
incorporation inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings, we 
may incur additional costs associated with resolving such matters in other jurisdictions, which could adversely affect our 
business and financial condition. 

This exclusive forum provision would not apply to suits brought to enforce a duty or liability created by the Securities 
Exchange Act of 1934, as amended, which provides for exclusive jurisdiction of the federal courts. It could apply, however, to a 
suit that falls within one or more of the categories enumerated in the exclusive forum provision and asserts claims under the 
Securities Act of 1933, as amended, or the Securities Act, inasmuch as Section 22 of the Securities Act creates concurrent 
jurisdiction for federal and state courts over all suits brought to enforce any duty or liability created by the Securities Act or the 
rules and regulations thereunder, provided, that with respect to claims under the Securities Act, our stockholders will not be 
deemed to have waived our compliance with the federal securities laws and the rules and regulations thereunder. 

If securities analysts do not publish research or reports about our business or if they publish negative evaluations of our 
stock, the price of our stock and trading volume could decline. 

85 

 
 
 
 
 
 
 
 
 
The trading market for our common stock depends, in part, on the research and reports that industry or financial analysts 
publish about us or our business. If one or more of the analysts covering our business downgrade their evaluations of our stock, 
the price of our stock could decline. If one or more of these analysts cease to cover our stock or fail to regularly publish reports 
on us, we could lose visibility in the market for our stock, which in turn could cause our stock price to decline. 

A portion of our total outstanding shares may be sold into the market in the near future, which could cause the market price 
of our common stock to decline significantly, even if our business is doing well. 

Sales of a significant number of shares of our common stock in the public market could occur at any time. These sales, or the 
perception in the market that the holders of a large number of shares of common stock intend to sell shares, could reduce the 
market price of our common stock. 

We have registered substantially all shares of common stock that we may issue under our equity compensation plans. These 
shares can be freely sold in the public market upon issuance and once vested, subject to volume limitations applicable to 
affiliates. If any of these additional shares are sold, or if it is perceived that they will be sold, in the public market, the market 
price of our common stock could decline. 

General Risk Factors 

Unfavorable global economic or geopolitical conditions could adversely affect our business, financial condition or results of 
operations. 

Our results of operations could be adversely affected by general conditions in the global economy, geopolitical considerations 
and global financial market conditions, including changes in inflation, interest rates and overall economic conditions and 
uncertainties. For example, the global financial crisis caused extreme volatility and disruptions in the capital and credit markets. 
We cannot assure stockholders that deterioration of the global credit and financial markets would not negatively impact our 
stock price, our current portfolio of cash equivalents or investments, or our ability to meet our financing objectives. If the 
current equity and credit markets deteriorate, it may make any necessary debt or equity financing more difficult, more costly, 
and more dilutive. Failure to secure any necessary financing in a timely manner and on favorable terms could have a material 
adverse effect on our growth strategy, financial performance and stock price and could require us to delay or abandon clinical 
development plans. A weak or declining economy, could also strain our suppliers and vendors involved in our clinical 
development activities.  

Additionally, Russia’s invasion of Ukraine in February 2022 and the global response, including the imposition of sanctions by 
the United States and other countries, could create or exacerbate risks facing our business. We have evaluated our operations, 
vendor contracts and clinical trial arrangements, and at present we do not expect the conflict to directly have a materially 
adverse effect on our financial condition or results of operations. However, if the hostilities persist, escalate or expand, other 
risks we have identified in this report may be exacerbated. For example, if our supply arrangements or clinical sites are 
disrupted due to expanded sanctions or involvement of countries where we have operations or relationships, our business could 
be materially disrupted. Further, the use of state-sponsored cyberattacks could expand as part of the conflict, which could 
adversely affect our ability to maintain or enhance our cyber security and data protection measures. Any of the foregoing could 
harm our business, and we cannot anticipate all of the ways in which the current economic and geopolitical climate and 
financial market conditions could adversely impact our business. 

We, or the third parties upon whom we depend, may be adversely affected by serious disasters. 

Any  unplanned  event,  such  as  a  flood,  fire,  explosion,  earthquake,  extreme  weather  condition,  medical  epidemic,  power 
shortage, telecommunication failure or other natural or human-made accident or incident that results in us being unable to fully 
use our facilities, or the facilities of third parties with which we contract, may have a material and adverse effect on our ability 
to  operate  our  business  and  may  have  significant  negative  consequences  on  our  financial  and  operating  conditions.  Loss  of 
access to these facilities or operations may result in increased costs, delays in the development of our current or future product 
candidates or the interruption of our business operations for a substantial period of time. 

There can be no assurance that the amounts of insurance that we maintain will be sufficient to satisfy any damages and losses in 
the event a serious disaster or similar event occurs. If our facilities, or the manufacturing facilities of our third-party contract 
manufacturers, are unable to operate because of an accident or incident or for any other reason, even for a short period of time, 
any or all of our research and development programs and commercialization efforts may be harmed. 

86 

 
 
 
 
 
 
 
 
Our  business  is  subject  to  risks  arising  from  the  outbreaks  of  disease,  such  as  epidemics  or  pandemics,  including  the 
ongoing COVID-19 pandemic. 

The widespread infection of COVID-19 in the United States and abroad has caused significant volatility and uncertainty in U.S. 
and international markets, which could result in a prolonged economic downturn that may disrupt our business, including by 
adversely affecting our ability to conduct financings on terms acceptable to us, if at all. 

In  addition,  we  may  experience  disruptions  that  could  severely  impact  our  business,  preclinical  studies  and  clinical  trials, 
including: 

•  Our  clinical  trials  may  be  adversely  affected,  delayed  or  interrupted,  including,  for  example,  site  initiation,  patient 
recruitment  and  enrollment,  availability  of  clinical  trial  materials,  and  data  analysis.  Some  patients  and  clinical 
investigators may not be able to comply  with  clinical  trial protocols and patients  may choose  to  withdraw from our 
trials  or  we  may  have  to  pause  enrollment  or  we  may  choose  to  or  be  required  to  pause  enrollment  and  or  patient 
dosing in our ongoing clinical trials in order to preserve health resources and protect clinical trial participants, which 
could delay our clinical trials or impact the strength or validity of our clinical trial data. It is unknown how long these 
pauses or disruptions could continue. 

•  We  currently  rely  on  third  parties  to,  among  other  things,  manufacture  raw  materials,  manufacture  our  product 
candidates  for  our  clinical  trials,  ship  investigational  drugs  and  clinical  trial  samples,  perform  quality  testing  and 
supply  other  goods  and  services  to  run  our  business.  If  any  such  third  party  in  our  supply  chain  for  materials  are 
adversely impacted by restrictions resulting from the coronavirus pandemic, including staffing shortages, raw material 
supplies,  production  slowdowns  or  disruptions  in  delivery systems,  our  supply  chain  may  be  disrupted,  limiting our 
ability  to  manufacture  our  product  candidates  for  our  clinical  trials  and  conduct  our  research  and  development 
operations. 

•  Our  increased  reliance  on  personnel  working  from  home  may  negatively  impact  productivity,  or  disrupt,  delay,  or 
otherwise  adversely  impact  our  business.  In  addition,  this  could  increase  our  cyber  security  risk,  create  data 
accessibility  concerns,  and  make  us  more  susceptible  to  communication  disruptions,  any  of  which  could  adversely 
impact  our  business  operations  or  delay  necessary  interactions  with  local  and  federal  regulators,  ethics  committees, 
manufacturing sites, research or clinical trials sites and other important agencies and contractors. 

•  Our  employees  and  contractors  conducting  research  and  development  activities  may  not  be  able  to  access  our 
laboratory for an extended period of time as a result of the closure of our offices and the possibility that governmental 
authorities further modify current restrictions. As a result, this could delay timely completion of preclinical activities, 
including  completing  IND-enabling  studies  or  our  ability  to  select  future  development  candidates,  and  initiation  of 
additional clinical trials for other of our development programs. 

•  Health  regulatory  agencies  globally  may  experience  disruptions  in  their  operations  as  a  result  of  the  COVID-19 
pandemic.  The  FDA  and  comparable  foreign  regulatory  agencies  may  have  slower  response  times  or  be  under-
resourced  to  continue  to  monitor  our  clinical  trials  and,  as  a  result,  review,  inspection,  and  other  timelines  may  be 
materially delayed. It is unknown how long these disruptions could continue, were they to occur. Any prolongation or 
de-prioritization  of  our  clinical  trials  or  delay  in  regulatory  review  resulting  from  such  disruptions  could  materially 
affect  the  development  of  our  product  candidates.  For  example,  regulatory  authorities  may  require  that  we  not 
distribute  a  product  candidate  lot  until  the  relevant  agency authorizes  its  release.  Such  release  authorization  may  be 
delayed as a result of the COVID-19 pandemic and could result in delays to our clinical trials. 

•  The  ongoing  COVID-19  pandemic  may  cause  the  trading  prices  for  shares  of  our  common  stock  and  other 
biopharmaceutical companies' shares to be highly volatile. As a result, we may face difficulties raising capital through 
sales of shares of our common stock, or such sales may be on unfavorable terms. In addition, a recession, depression 
or  other  sustained adverse market  event resulting from  the spread  of the  coronavirus could materially  and adversely 
affect our business and the value of our common stock. 

The COVID-19 pandemic continues to evolve. The ultimate impact of the coronavirus pandemic on our business operations is 
highly  uncertain  and  subject  to  change  and  will  depend  on  future  developments,  which  cannot  be  accurately  predicted, 
including  the  duration  of  the  pandemic,  the  emergence  and  severity  of  new  variants  of  the  virus,  additional  or  modified 
government  actions,  new  information  that  will  emerge  concerning  the  severity  and  impact  of  COVID-19,  the  timing, 
availability, efficacy, adoption and distribution of vaccines or other preventative treatments and other actions taken to contain 
coronavirus or address its impact in the short and long term, among others. We do not yet know and are unable to predict the 

87 

 
full extent of potential delays or impacts on our business, our clinical trials, our research programs, healthcare systems or the 
global economy. 

ITEM 1B. 

UNRESOLVED STAFF COMMENTS. 

None. 

ITEM 2. 

PROPERTIES. 

Our  corporate  headquarters  are  located  in  Cambridge,  Massachusetts. We  occupy  approximately  45,000  square  feet  of  office 
and laboratory space that we lease in a multi-tenant building in which our corporate headquarters are located. The lease for the 
substantial majority of this space expires in March 2026. We have an option to extend the lease term for an additional five years 
thereafter. We believe that this office and laboratory space is sufficient to meet our current needs and that suitable additional 
space will be available as and when needed. 

ITEM 3. 

LEGAL PROCEEDINGS. 

From  time  to  time,  we  may  become  subject  to  various  legal  proceedings  and  claims  that  arise  in  the  ordinary  course  of  our 
business activities. We are not currently party to any material legal proceedings. Additionally, although the results of litigation 
and claims cannot be  predicted with certainty,  as of the date  of this Annual  Report  on Form 10-K, we do  not  believe we are 
party to any claim or litigation, the outcome of which, if determined adversely to us, would individually or in the aggregate be 
reasonably expected to have a material adverse effect on our business.  

ITEM 4. 

MINE SAFETY DISCLOSURES. 

Not applicable. 

88 

 
 
PART II 

ITEM 5. 

MARKET  FOR  REGISTRANT’S  COMMON  EQUITY,  RELATED  STOCKHOLDER  MATTERS 
AND ISSUER PURCHASES OF EQUITY SECURITIES 

Certain Information Regarding the Trading of Our Common Stock 

Our common stock trades under the symbol “MRSN” on the Nasdaq Global Select Market. As of February 24, 2023, there were 
19 holders of record of shares of our common stock. The actual number of stockholders is greater than this number of record 
holders, and includes stockholders who are beneficial owners, but whose shares are held in street name by brokers and other 
nominees. 

Dividend Policy 

We have never declared nor paid cash dividends on our common stock. We currently intend to retain all of our future earnings, 
if  any,  to  finance  the  growth  and  development  of  our  business.  We  do  not  intend  to  pay  cash  dividends  in  respect  of  our 
common stock in the foreseeable future. In addition, our current credit facility contains restrictive covenants that prohibit us, 
subject to certain exceptions, from paying dividends on our common stock. Any future determination to pay cash dividends will 
be made at the discretion of our board of directors and will depend on restrictions and other factors our board of directors may 
deem relevant. Investors should not purchase our common stock with the expectation of receiving cash dividends. 

Stock Performance Graph 

The following performance graph and related information shall not be deemed to be “soliciting material” or to be “filed” with 
the  Securities  and  Exchange  Commission,  or  SEC,  for  purposes  of  Section 18  of  the  Securities  Exchange  Act  of  1934,  as 
amended,  or  the  Exchange  Act,  nor  shall  such  information  be  incorporated  by  reference  into  any  future  filing  under  the 
Exchange Act or Securities Act of 1933, as amended, or the Securities Act, except to the extent that we specifically incorporate 
it by reference into such filing. 

The  following  graph  compares  the  performance  of  our  common  stock  to  the  Nasdaq  Composite  Index  and  to  the  Nasdaq 
Biotechnology Index  from  December  31,  2017  through  December 31,  2022,  which  was  the  last  trading  day  of  the  year. The 
comparison assumes $100 was invested in our common stock and in each of the foregoing indices after the market closed on 
December 31, 2017, and it assumes reinvestment of dividends, if any. The stock price performance included in this graph is not 
necessarily indicative of future stock price performance. 

89 

 
 
Recent Sales of Unregistered Securities 

None. 

Purchases of Equity Securities by the Issuer and Affiliates Purchasers 

Neither we nor any affiliated purchaser or anyone acting on behalf of us or an affiliated purchaser made any purchases of shares 
of our common stock during the fourth quarter of 2022.  

ITEM 6. 

[RESERVED] 

ITEM 7. 

MANAGEMENT’S  DISCUSSION AND ANALYSIS  OF  FINANCIAL  CONDITION AND  RESULTS 
OF OPERATIONS 

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with 
our audited financial statements and related notes appearing elsewhere in this Annual Report on Form 10-K.  

Our  actual  results  and  timing  of  certain  events  may  differ  materially  from  the  results  discussed,  projected,  anticipated,  or 
indicated  in  any  forward-looking  statements.  We  caution  you  that  forward-looking  statements  are  not  guarantees  of  future 
performance and that our actual results of operations, financial condition and liquidity, and the development of the industry in 
which we operate may differ materially from the forward-looking statements contained in this Annual Report. In addition, even 
if  our  results  of  operations,  financial  condition  and  liquidity,  and  the  development  of  the  industry  in  which  we  operate  are 
consistent  with  the  forward-looking  statements  contained  in  this  Annual  Report,  they  may  not  be  predictive  of  results  or 
developments in future periods. 

The following information and any forward-looking statements should be considered in light of factors discussed elsewhere in 
this Annual Report on Form 10-K, including those risks identified under Part II, Item 1A. Risk Factors. 

We caution readers not to place undue reliance on any forward-looking statements made by us, which speak only as of the date 
they are made. We disclaim any obligation, except as specifically required by law and the rules of the Securities and Exchange 
Commission, or SEC, to publicly update or revise any such statements to reflect any change in our expectations or in events, 
conditions or circumstances on which any such statements may be based, or that may affect the likelihood that actual results 
will differ from those set forth in the forward-looking statements. 

For our discussion and analysis of the year ended December 31, 2021 compared to the year ended December 31, 2020, please 
refer  to  “Item  7.  Management’s  Discussion  and  Analysis  of  Financial  Condition  and  Results  of  Operations”  in  our  Annual 
Report on Form 10-K for the year ended December 31, 2021, as filed with the SEC on February 28, 2022. 

Overview 

We  are  a  clinical-stage  biopharmaceutical  company  focused  on  developing  antibody-drug  conjugates,  or ADCs,  that  offer  a 
clinically  meaningful  benefit  for  cancer  patients  with  significant  unmet  need.  We  have  leveraged  over  20  years  of  industry 
learning in the ADC field to develop three proprietary and differentiated technology platforms that enable us to develop ADCs 
designed to have improved efficacy, safety and tolerability relative to existing ADCs and other approved therapies. We believe 
that  our  innovative  platforms  and  our  proprietary  payloads  together  enable  a  robust  discovery  pipeline  for  us  and  our 
collaborators. Our investments in our novel and proprietary auristatin DolaLock payload, as well as our novel and proprietary 
STING  (stimulator  of  interferon  genes)  agonist  ImmunoLock  payload,  together  with  the  GMP  supply  chain  established  for 
Dolaflexin,  Dolasynthen  and Immunosynthen  all  enable our  ability  to  apply  these  platforms  to  new  and  different  targets  and 
antibodies to create new product candidates. We call this our product engine. Our ADCs in preclinical studies and clinical trials 
include first-in-class molecules that target multiple tumor types with high unmet medical need.  

Our goal is to become a leading oncology company by leveraging the potential of our innovative and differentiated ADC 
platforms and the experience and competencies of our management team to discover and develop promising ADC product 
candidates and to commercialize cancer therapeutics that address unmet medical needs or provide significant benefits to 
patients. 

90 

 
 
 
Our lead product candidate, upifitamab rilsodotin, which we refer to as UpRi, is a first-in-class Dolaflexin ADC targeting 
NaPi2b, an antigen broadly expressed in ovarian cancer and other cancers. We are currently evaluating UpRi in platinum-
resistant ovarian cancer in a single-arm registrational trial, which we refer to as UPLIFT, for which we completed enrollment of 
approximately 270 patients in October 2022. We expect to report top-line data from UPLIFT in mid-2023 following the major 
oncology conferences scheduled for June, and, if the data are positive, to submit a biologics license application, or BLA, to the 
U.S. Food and Drug Administration, or FDA, under the accelerated approval pathway around the end of 2023. We also initiated 
screening of patients in UP-NEXT, our Phase 3 clinical trial of UpRi as monotherapy maintenance treatment following 
treatment with platinum doublets in recurrent platinum-sensitive ovarian cancer, in the third quarter of 2022, and we continue to 
enroll patients in this trial. If data from the trial are positive, we believe UP-NEXT could serve as a post-approval confirmatory 
trial in the United States, support potential approvals outside of the United States and support UpRi’s expansion into earlier 
lines of therapy. Additionally, we are also conducting a Phase 1 combination trial, which we refer to as UPGRADE-A, 
exploring the combination of UpRi with carboplatin, a standard platinum chemotherapy broadly used in the treatment of 
platinum-sensitive ovarian cancer. We have completed the dose escalation portion of UPGRADE-A, initiated the dose 
expansion portion of UPGRADE-A in January 2023, and expect to present data from the trial in the second half of 2023. We 
may explore UpRi in combination with other therapies in a series of UPGRADE trials. Together, data from all of our clinical 
trials of UpRi have the potential to establish the safety and efficacy of UpRi across a wide range of ovarian cancer patients, 
from those who are platinum-resistant and heavily pre-treated to those in earlier lines of the disease. 

We  are  investigating  two  additional  ADCs,  XMT-1660  and  XMT-2056,  in  Phase  1  clinical  trials.  XMT-1660  is  a  B7-H4-
directed Dolasynthen ADC designed with a precise, target-optimized drug-to-antibody ratio, or DAR, of 6 and our DolaLock 
microtubule inhibitor payload with controlled bystander effect. We are currently enrolling patients in our multicenter Phase 1 
trial investigating the safety, tolerability and anti-tumor activity of XMT-1660 in patients with breast, endometrial and ovarian 
cancers, for which trial we began dosing patients in August 2022. The FDA has granted Fast Track designation to XMT-1660 
for  the  treatment  of  adult  patients  with  advanced  or  metastatic  triple-negative  breast  cancer.  XMT-2056  is  a  systemically 
administered  Immunosynthen  STING  agonist ADC  (DAR  8)  that  is  designed  to  target  a  novel  epitope  of  human  epidermal 
growth  factor  receptor  2,  or  HER2,  distinct  from  that  targeted  by  either  trastuzumab  or  pertuzumab,  and  to  locally  activate 
STING signaling in both tumor-resident immune cells and in tumor cells, providing the potential to treat patients with HER2-
high or -low tumors as monotherapy and in combination with standard-of-care agents. We initiated a multicenter Phase 1 open-
label trial of XMT-2056 in previously treated patients with advanced/recurrent solid tumors expressing HER2, including breast, 
gastric, colorectal and non-small cell lung cancers, in January 2023. 

We also have two earlier stage preclinical candidates, which we refer to as XMT-2068 and XMT-2175, that leverage our 
Immunosynthen platform. 

In May 2022, we made the decision to discontinue the development of XMT-1592, a Dolasynthen ADC that had been in a 
Phase 1 dose exploration trial in patients with ovarian cancer and NSCLC, and to close this company-sponsored trial, which 
was completed in September 2022. 

We have entered into a global collaboration providing GlaxoSmithKline Intellectual Property (No. 4) Limited, or GSK, an 
exclusive option to co-develop and commercialize XMT-2056. In addition, we have established strategic research and 
development collaborations with Janssen Biotech, Inc., or Janssen, and Merck KGaA, Darmstadt, Germany, or Merck KGaA, 
and its affiliates for the development and commercialization of additional ADC product candidates leveraging our proprietary 
Dolasynthen, Dolaflexin and Immunosynthen platforms against a limited number of targets selected by our collaborators. We 
believe the potential of our ADC product candidates and platforms, supported by our scientific and technical expertise and 
enabled by our intellectual property strategy, all support our independent and collaborative efforts to discover and develop life-
changing ADCs for patients fighting cancer. 

Since inception, our operations have focused on building our platforms, identifying potential product candidates, producing 
drug substance and drug product material for use in preclinical studies, conducting preclinical and toxicology studies, 
manufacturing clinical trial material and conducting clinical trials, establishing and protecting our intellectual property, staffing 
our company and raising capital. We do not have any products approved for sale and have not generated any revenue from 
product sales. We have funded our operations primarily through our strategic collaborations, private placements of our 
convertible preferred stock and public offerings of our common stock, including through our at-the-market, or ATM, equity 
offering programs. 

91 

 
 
 
 
 
 
Since  inception,  we  have  incurred  significant  cumulative  operating  losses.  Our  net  losses  were  $204.2 million  and  $170.1 
million  for  the  years  ended  December 31,  2022  and  2021,  respectively.  As  of  December 31,  2022,  we  had  an  accumulated 
deficit of $654.7 million. We expect to continue to incur significant expenses and operating losses over the next several years. 
We anticipate that our expenses will increase significantly in connection with our ongoing activities, as we: 

• 

• 

• 

• 

continue clinical development and manufacturing activities for UpRi, XMT-1660 and XMT-2056; 

prepare for a potential BLA submission for UpRi around the end of 2023 and engage in preparations for a potential 
commercial launch of UpRi, if approved, in 2024; 

continue diagnostic development efforts with respect to the NaPi2b biomarker; 

continue  activities  to  discover,  validate  and  develop  additional  product  candidates,  including  XMT-2068  and  XMT-
2175; 

•  maintain, expand and protect our intellectual property portfolio; and 

• 

hire additional research, development and general and administrative personnel. 

92 

 
 
Financial Operations Overview 

Revenue 

To date, we have not generated any revenue from the sale  of products. All of our  revenue has been generated  from  strategic 
collaborations. 

In December 2022, we entered into a collaboration and commercial license agreement, or the 2022 Merck KGaA Agreement, 
with Ares Trading S.A., or MRKDG, a wholly-owned subsidiary of Merck KGaA, for the development and commercialization 
of ADC  product  candidates  utilizing  our  Immunosynthen  platform  for up  to  two  target  antigens.  MRKDG  is  responsible  for 
generating  antibodies  against  the  target  antigens,  and  we  are  responsible  for  performing  bioconjugation  activities  to  create 
ADCs as well as certain chemistry, manufacturing and controls development and early-stage manufacturing activities at their 
cost. MRKDG has the exclusive right to and is responsible for the further development and commercialization of these ADC 
product  candidates.  We  did  not  recognize  revenue  related  to  the  2022  Merck  KGaA  Agreement  during  the  year  ended 
December 31, 2022.  

In August 2022, we entered into a collaboration, option and license agreement, or the GSK Agreement, with GSK to provide 
GSK  with  an  exclusive  option  to  obtain  an  exclusive  license  to  co-develop  and  to  commercialize  products  containing  XMT-
2056, or Licensed Products. We are responsible for manufacturing, research and early clinical development related to our XMT-
2056 program prior to GSK's exercise, if any, of its option. If GSK exercises its option, GSK will have the exclusive right to 
and  will  be  responsible  for  the  further  co-development  and  commercialization  of  Licensed  Products.  During  the  year  ended 
December 31, 2022, we recognized $2.0 million of collaboration revenue related to the GSK Agreement. 

In February 2022, we entered into a research collaboration and license agreement, or the Janssen Agreement, with Janssen for 
the  development and commercialization  of ADC product candidates utilizing our  Dolasynthen  platform for  up  to three  target 
antigens.  Janssen  is  responsible  for  generating  antibodies  against  the  target  antigens,  and  we  are  responsible  for  performing 
bioconjugation activities to create ADCs as well as certain chemistry, manufacturing and controls development and early-stage 
manufacturing activities at Janssen's cost. Janssen has the exclusive right to and is responsible for the further development and 
commercialization of these ADC product candidates. During the year ended December 31, 2022, we recognized $24.2 million 
of collaboration revenue related to performance under the Janssen Agreement and an associated development milestone.  

In June 2014, we entered into a collaboration and commercial license agreement, or the 2014 Merck KGaA Agreement, with 
Merck KGaA for the development and commercialization of ADC product candidates utilizing our Dolaflexin platform for up 
to six target antigens. Merck KGaA is responsible for generating antibodies against the target antigens, and we are responsible 
for generating Dolaflexin and conjugating this to such antibodies to create the ADC product candidates. Merck KGaA has the 
exclusive right to and is responsible for the further development and commercialization of these ADC product candidates. In 
May 2018, we entered into a supply agreement, or the Merck KGaA Supply Agreement, with Merck KGaA for the supply of 
materials that could be used for investigational new drug, or  IND,  -enabling studies  and  clinical  trials.  For  each  of the  years 
ended  December 31,  2022  and  2021,  we  recognized  an  immaterial  amount  of  revenue  related  to  the  2014  Merck  KGaA 
Agreement and Merck KGaA Supply Agreement. 

During  the  year  ended  December 31,  2022,  we  recognized  $0.3  million  of  revenue  related  to  services  provided  to  Asana 
BioSciences,  LLC,  or Asana  Biosciences. We  did  not  recognize  revenue  related  to Asana  Biosciences  during  the  year  ended 
December 31, 2021. 

For the foreseeable future, we expect substantially all of our revenue to be generated from our collaboration agreements with 
GSK, Janssen, Merck KGaA and its affiliate, MRKDG, and Asana BioSciences. Given the uncertain nature and timing of 
clinical development, we cannot predict when or whether we will receive further milestone payments or any royalty payments 
under these collaborations. 

93 

 
 
Expenses 

Research and development expenses 

Research  and  development  expenses  include  our  drug  discovery  efforts,  manufacturing,  and  the  development  of  our  product 
candidates, which consist of: 

• 

• 

• 

• 

• 

employee-related expenses, including salaries, benefits and stock-based compensation expense; 

costs  of  funding  research  and  development  performed  by  third  parties  that  conduct  research,  preclinical  activities, 
manufacturing and clinical trials on our behalf; 

laboratory supplies; 

facility costs, including rent, depreciation and maintenance expenses; and 

upfront and milestone payments under our third-party licensing agreements. 

Research and development costs are expensed as incurred. Costs of certain activities, such as manufacturing, preclinical studies 
and clinical trials, are  generally recognized based on  an  evaluation  of the  progress to  completion  of  specific  tasks. Costs for 
certain development activities, such as clinical trials,  are  recognized  based on an  evaluation  of the  progress  to completion  of 
specific tasks using data such as patient enrollment, clinical site activations and information provided to us by the third parties 
with whom we contract. 

Research  and  development  activities  are  central  to  our  business  model.  Product  candidates  in  later  stages  of  clinical 
development generally have higher development costs than those in earlier stages of clinical development, primarily due to the 
increased  size  and  duration  of  later-stage  clinical  trials  and  manufacturing  costs.  We  expect  that  our  future  research  and 
development  costs  will  continue  to  increase  over  current  levels,  depending  on  the  progress  of  our  clinical  development 
programs. There are numerous factors associated with the successful development and commercialization of any of our product 
candidates,  including  future  trial  design  and  various  regulatory  requirements,  many  of  which  cannot  be  determined  with 
accuracy at our current stage of development. Additionally, future commercial and regulatory factors beyond our control may 
impact our clinical development programs and plans. 

We have not historically allocated all of our internal research and development expenses on a program-by-program basis as our 
employees  and  other  resources  are  deployed  across  multiple  projects  under  development.  Internal  research  and  development 
expenses are presented as one total. Our internal research and development costs are primarily personnel-related costs, stock-
based compensation costs, and facility costs, including depreciation and lab consumables.  

We  incur  significant  external  costs  for  manufacturing  our  product  candidates  and  platforms  and  for  clinical  research 
organizations that conduct clinical trials on our behalf. We capture these external expenses for each product candidate in clinical 
development. Costs for our platforms with an associated product candidate in clinical development are typically allocated to our 
most  clinically  advanced  product  candidate  based  on  that  platform.  In  light  of  our  decision  to  discontinue  further  clinical 
development  of  XMT-1592  in  the  second  quarter  of  2022,  all  costs  associated  with  our  Dolasynthen  platform  were 
prospectively re-allocated to XMT-1660, which is now our lead Dolasynthen-based product candidate, following such decision. 
All external research and development expenses not attributable to our product candidates in clinical development are captured 
within preclinical and discovery costs. These costs relate to our product candidates XMT-2068 and XMT-2175 and additional 
earlier  discovery  stage  programs  and  certain  unallocated  costs.  The  following  table  summarizes  our  external  research  and 
development expenses, presented by program as described above, for each of the years ended December 31, 2022, 2021, and 
2020. 

94 

 
 
 
 
(in thousands) 
UpRi external costs 
XMT-1660 external costs 
XMT-2056 external costs 
XMT-1592 external costs 
Preclinical and discovery costs 
Internal research and development costs 
Total research and development costs 

Year Ended 
December 31, 
2021 

2022 

66,119     $ 
15,032     
4,981     
3,802     
14,991     
68,460     
173,385    $ 

45,511     $ 
—     
—     
9,126     
28,464     
48,912     
132,013    $ 

$ 

$ 

2020 

18,689  
—  
—  
7,180  
9,883  
31,284  
67,036  

The successful development of our product candidates is highly uncertain. As such, we cannot reasonably estimate or know the 
nature, timing and estimated costs of the efforts that  will  be  necessary  to  complete  the remainder  of  the  development  of  our 
product candidates. We are also unable to predict when, if ever, we will generate revenue from commercialization and sale of 
any of our product candidates that obtain  regulatory  approval. This  is due to the  numerous  risks and uncertainties  associated 
with developing drugs, including the uncertainty of: 

• 

• 

• 

• 

• 

• 

• 

successful completion of preclinical studies and IND-enabling studies; 

successful enrollment in and completion of clinical trials; 

receipt of marketing approvals from applicable regulatory authorities; 

establishing commercial manufacturing capabilities or making arrangements with third-party manufacturers; 

obtaining and maintaining patent and trade secret protection and regulatory exclusivity for our product candidates; 

commercializing the product candidates, if and when approved, whether alone or in collaboration with others; and 

continued acceptable safety profile of the drugs following approval. 

A change in the outcome of any of these variables with respect to the development, manufacture or commercialization of any of 
our product candidates would significantly change the costs, timing and viability associated with the development of that 
product candidate. 

We expect our research and development expenses to increase as we continue our clinical development and manufacturing of 
UpRi, XMT-1660 and XMT-2056, advance our preclinical pipeline and invest in improvements in our ADC technologies. 

General and administrative expenses 

General  and  administrative  expenses  consist  primarily  of  salaries  and  other  employee-related  costs,  including  stock-based 
compensation, for personnel in executive, finance, accounting, business development, legal operations, information technology 
and  human  resources  functions.  Other  significant  costs  include  facility  costs  not  otherwise  included  in  research  and 
development expenses, legal fees relating to patent and corporate matters and fees for accounting and consulting services. 

We  expect  our  general  and  administrative  expenses  to  increase  in  the  future  to  support  continued  research  and  development 
activities,  including increased costs related  to  the  hiring of additional  personnel, fees  to outside consultants  and patent costs, 
among other expenses. 

Other income (expense) 

Other  income  (expense)  consists  primarily  of  interest  expense  related  to  borrowings  under  our  credit  facility  and  associated 
amortization of the deferred financing costs and the accretion of debt discount. Interest income includes interest earned on cash 
equivalents and marketable securities.  

95 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Results of Operations 

Comparison of Years Ended December 31, 2022 and 2021 

The following table summarizes our results of operations for the years ended December 31, 2022 and 2021, together with the 
changes in those items: 

(in thousands) 
Collaboration revenue 
Operating expenses: 

Research and development 
General and administrative 

Total operating expenses 
Other income (expense): 

Interest income 
Interest expense 

Total other expense, net 
Net loss 

Collaboration Revenue 

Year Ended 
December 31, 

2022 

$ 

26,581    $ 

2021 

Dollar Change 
26,538  

43    $ 

173,385     
56,963     
230,348     

132,013     
36,888     
168,901     

2,883     
(3,328)    
(445)    
(204,212)   $ 

65     
(1,267)    
(1,202)    
(170,060)   $ 

$ 

41,372  
20,075  
61,447  

2,818  
(2,061) 
757  
(34,152) 

Collaboration  revenue  increased  by  $26.5  million  during  the  year  ended  December 31,  2022  as  compared  to  the year  ended 
December 31, 2021, primarily due to collaboration revenue of $24.2 million recognized under the Janssen Agreement and $2.0 
million recognized under the GSK Agreement. 

Research and Development Expense 

Research and development expense increased by $41.4 million from $132.0 million for the year ended December 31, 2021 to 
$173.4 million for the year ended December 31, 2022. 

The increase in research and development expense was primarily due to the following: 

• 

• 

• 

• 

• 

• 

an increase of $21.6 million related to manufacturing and clinical development activities for UpRi; 

an increase of $14.5 million related to employee compensation (excluding stock-based compensation), primarily due 
to an increase in headcount supporting the growth of our research and development activities; 

an increase of $2.3 million related to clinical development activities for XMT-1660; 

an increase of $2.2 million related to manufacturing activities for XMT-1660 and the Dolasynthen platform; 

an increase of $1.5 million related to manufacturing and clinical development activities for XMT-2056; and 

an increase of $1.4 million related to consulting and professional fees. 

These  increased  costs  were  partially  offset  by  a  decrease  of  $3.4  million  related  to  manufacturing  and  clinical  development 
activities for XMT-1592. 

Stock-based  compensation  expense  included  in  research  and  development  expenses  increased  by  $1.4  million  primarily  as  a 
result of increased headcount. 

96 

 
 
 
 
 
 
  
  
 
 
 
 
  
  
 
 
 
General and Administrative Expense 

General and administrative expense increased by $20.1  million from $36.9 million for  the  year ended  December 31, 2021 to 
$57.0 million for the year ended December 31, 2022. The increase in general and administrative expense was primarily due to 
an  increase  of  $11.1  million  related  to  consulting  and  professional  fees  and  an  increase  of  $7.1  million  related  to  employee 
compensation (excluding stock-based compensation) due to an increase in headcount. Stock-based compensation increased by 
$1.7 million, also primarily as a result of increased headcount. 

Total Other Expense, Net 

Total other expense, net was $0.4 million and $1.2 million for the years ended December 31, 2022 and 2021, respectively. The 
increase  to  the  net  balance  was  primarily  due  to  an  increase  in  interest  income  earned  on  marketable  securities  partially 
offsetting an increase in interest expense related to borrowings under the New Credit Facility, as defined below. 

Liquidity and Capital Resources 

Sources of Liquidity 

We have financed our operations to date primarily through our strategic collaborations, private placements of our convertible 
preferred stock and public offerings of our common stock, including our initial public offering, our follow-on public offerings 
in 2019 and 2020 and our ATM equity offering programs.  

In May 2020, we established an ATM equity offering program, the 2020 ATM, pursuant to which we were able to offer and sell 
to the public through Cowen and Company, LLC, or Cowen, as sales agent, up to $100.0 million of our common stock from 
time to time at prevailing market prices. During the year ended December 31, 2021, we sold approximately 4.0 million shares 
of common stock under the 2020 ATM, resulting in net proceeds of $43.1 million. During the year ended December 31, 2022, 
we sold approximately 11.7 million shares of common stock under the 2020 ATM, resulting in gross proceeds and net proceeds 
of $55.9 million and $54.8 million, respectively. No shares were sold under the 2020 ATM during the quarter ended December 
31, 2022. As of December 31, 2022, there were no amounts remaining unsold and available for sale under the 2020 ATM. 

In February 2022, we entered into a new sales agreement, or the February 2022 ATM, with Cowen, as sales agent, under which 
we  are  able  to  offer  and  sell  to  the  public  through  Cowen  up  to  $100.0 million  of  our  common  stock  from  time  to  time  at 
prevailing market prices. During the quarter ended December 31, 2022, we sold approximately 6.0 million shares of common 
stock  under  the  February  2022  ATM,  resulting  in  gross  proceeds  and  net  proceeds  of  $40.7  million  and  $39.9  million, 
respectively. During the year ended December 31, 2022, we sold approximately 18.8 million shares of common stock under the 
February  2022  ATM,  resulting  in  gross  proceeds  and  net  proceeds  of  $98.4 million  and  $96.4 million,  respectively. 
Approximately $1.6 million remained unsold and available for sale under the February 2022 ATM as of December 31, 2022. 

In November 2022, we entered into an additional sales agreement, or the November 2022 ATM, with Cowen, as sales agent, 
under which we are able to offer and sell up to the public through Cowen to $150.0 million of our common stock from time to 
time at prevailing market prices. As of December 31, 2022, we had not sold any shares of common stock under the November 
2022 ATM. 

On May 8, 2019, we entered into a loan and security agreement, or the Prior Credit Facility, with Silicon Valley Bank, or SVB, 
which was subsequently amended on June 29, 2019, August 28, 2020 and August 27, 2021. On October 29, 2021, we entered 
into a loan and security agreement, or the New Credit Facility, with Oxford Finance LLC as the collateral agent and a lender, 
SVB as a lender, and the other lenders from time to time a party thereto, or together the Lenders. The New Credit Facility, as 
amended on February 17, 2022, October 17, 2022, and December 27, 2022, provides in aggregate up to $100 million in credit, 
which includes (i) $40 million available at our option in up to four principal advances through June 30, 2023, (ii) an additional 
$40 million in one principal advance, if we reach certain development milestone events, through September 30, 2023 and (iii) 
an additional tranche of $20 million, subject to conditional approval from the Lenders. On May 8, 2019, we drew $25 million 
from  the  facility, of  which $5.5  million  was  used  to  repay in  full  the  existing  balance  and  satisfy  our  existing  obligations  to 
SVB under the Prior Credit Facility. The New Credit Facility is secured by substantially all of our personal property owned or 
later acquired, excluding intellectual property (but including the right to payments and proceeds of intellectual property), and a 
negative pledge on intellectual property, which ensures that the Lenders' rights to repayment would be senior to the rights of the 
holders  of  our  common  stock  in  the  event  of  liquidation.  Upon  entering  into  the  New  Credit  Facility,  we  terminated  all 
commitments by SVB to extend further credit under the Prior Credit Facility and all guarantees and security interests granted by 
us to SVB under the Prior Credit Facility. 

97 

 
As of December 31, 2022, we had cash and cash equivalents and marketable securities of $280.7 million. In February 2023, we 
received the $30 million upfront payment due to us from MRKDG. In addition to our existing cash and cash equivalents and 
marketable  securities,  and  available  borrowings  under  the  New  Credit  Facility,  we  are  eligible  to  earn  milestone  and  other 
payments  under  our  collaboration  agreements  with  GSK,  Janssen,  Merck  KGaA  and  its  affiliate  MRKDG  and  Asana 
Biosciences. Our ability to earn the milestone payments and the timing of earning these amounts are dependent upon the timing 
and outcome of our development, regulatory and commercial activities and, as such, are uncertain at this time. 

Cash Flows 

The following table provides information regarding our cash flows for the years ended December 31, 2022, 2021 and 2020: 

(in thousands) 
Net cash used in operating activities 
Net cash (used in) provided by investing activities 
Net cash provided by financing activities 
Increase (decrease) in cash, cash equivalents and restricted cash 

Net Cash Used in Operating Activities 

Year Ended 
December 31, 
2021 
(139,988)   $ 
(648)    
63,646     
(76,990)   $ 

2022 
(49,363)   $ 
(152,716)    
153,017     
(49,062)   $ 

$ 

$ 

2020 
(74,696) 
37,027  
230,412  
192,743  

Net cash used in operating activities was $49.4 million for the year ended December 31, 2022 and primarily consisted of a net 
loss of $204.2 million adjusted for changes in our net working capital, deferred revenue related to our collaboration agreements, 
and  other  non-cash  items,  including  stock-based  compensation  of  $21.5  million.  Net  cash  used  in  operating  activities  was 
$140.0  million  for  the  year  ended  December 31,  2021  and  primarily  consisted  of  a  net  loss  of  $170.1  million  adjusted  for 
changes  in  our  net  working  capital  and  other  non-cash  items  including  stock-based  compensation  of  $18.4  million  and 
depreciation of $0.9 million. 

Net Cash Used in Investing Activities 

Net cash used in investing activities was $152.7 million during the year ended December 31, 2022 as compared to net cash used 
in investing activities of $0.6 million during the year ended December 31, 2021. During the year ended December 31, 2022, net 
cash  used  in  investing  activities  consisted  primarily  of  purchases  of  marketable  securities,  partially  offset  by  maturities  of 
marketable  securities.  Net  cash  used  in  investing  activities  for  the  year  ended  December 31,  2021  consisted  primarily  of  the 
purchase of property and equipment.  

Net Cash Provided by Financing Activities 

Net  cash  provided  by  financing  activities  was  $153.0 million  during  the  year  ended  December 31,  2022  as  compared  to 
$63.6 million  during  the year  ended  December 31,  2021.  During  the  year  ended  December 31,  2022  net  cash  provided  by 
financing activities consisted primarily of proceeds from the use of our 2020 ATM and February 2022 ATM of $150.9 million. 
During the year ended December 31, 2021, cash provided by financing activities consisted primarily of the proceeds from the 
use  of  the  2020  ATM  of  $43.1  million  and  issuance  of  debt,  net  of  issuance  costs,  of  $24.0  million  under  the  New  Credit 
Facility, as well as proceeds from exercise of stock options of $1.8 million, partially offset by repayment of debt of $5.5 million 
to repay the Prior Credit Facility. 

Funding Requirements 

We expect our cash expenditures to increase in connection with our ongoing activities, particularly as we continue the research 
and  development  and  manufacturing  of,  initiate  clinical  trials  of  and  seek  marketing  approval  for  our  product  candidates.  In 
addition,  as  we  prepare  for  and  if  we  obtain  marketing  approval  for  any  of  our  product  candidates,  we  expect  to  incur 
significant commercialization expenses related to drug sales, marketing, manufacturing and distribution to the extent that such 
sales, marketing and distribution are not the responsibility of potential collaborators.  

98 

 
 
 
 
 
 
 
As  of  December 31,  2022,  we  had  cash,  cash  equivalents  and  marketable  securities  of  $280.7  million,  and  we  subsequently 
received the $30 million up-front payment from MRKDG under the 2022 Merck KGaA Agreement. In addition, we currently 
have the option to borrow $15 million under the New Credit Facility. We believe our currently available funds plus available 
borrowings on the New Credit Facility will be sufficient to fund our current operating plan commitments into the second half of 
2024. Our forecast of the period of time through which our financial resources will be adequate to support our operations is a 
forward-looking statement and involves risks and uncertainties, and actual results could vary as a result of a number of factors. 
We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources 
sooner than we currently expect. Our future capital requirements will depend on many factors, including: 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

the scope, progress, results and costs of drug discovery, preclinical development, laboratory testing and clinical trials 
for our product candidates; 

the scope, prioritization and number of our research and development programs; 

the costs, timing and outcome of regulatory review of our product candidates; 

our ability to establish and maintain collaborations on favorable terms, if at all; 

the  achievement  of  milestones  or  occurrence  of  other  developments  that  trigger  payments  under  any  collaboration 
agreements we obtain; 

the  extent  to  which  we  are  obligated  to  reimburse,  or  entitled  to  reimbursement  of,  clinical  trial  costs  under  future 
collaboration agreements, if any; 

the costs of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property 
rights and defending intellectual property-related claims; 

the extent to which we acquire or in-license other product candidates and technologies; 

the costs of securing manufacturing arrangements for clinical and commercial production; and 

the costs of establishing or contracting for sales and marketing capabilities if we obtain regulatory approvals to market 
our product candidates. 

Identifying  potential  product candidates  and  conducting preclinical  testing  and  clinical  trials  is  a  time-consuming,  expensive 
and uncertain process that takes many years to complete, and we may never generate the necessary data or results required to 
obtain  marketing  approval  and  achieve  drug  sales.  In  addition,  our  product  candidates,  if  approved,  may  not  achieve 
commercial  success.  Our  commercial  revenues,  if  any,  will  be  derived  from  sales  of  drugs  that  we  do  not  expect  to  be 
commercially  available  for  many  years,  if  at  all.  Accordingly,  we  will  need  to  continue  to  rely  on  additional  financing  to 
achieve our business objectives. Adequate additional financing may not be available to us on acceptable terms, or at all. 

Until  such  time,  if  ever,  as  we  can  generate  substantial  product  revenues,  we  expect  to  finance  our  cash  needs  through  a 
combination of strategic collaborations, licensing arrangements, equity offerings and debt financings. To the extent that we raise 
additional capital through the sale of equity or convertible debt securities, the ownership interests of our common stockholders 
will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of 
our  common  stockholders.  We  currently  have  access  to  the  New  Credit  Facility,  as  described  above,  along  with  funds  to 
potentially be earned in connection with our agreements with GSK, Janssen, Merck KGaA and its affiliate MRKDG and Asana 
BioSciences, if research and development activities are successful under our collaborations with those parties. Future additional 
debt  financing,  if available, may involve agreements that include  covenants limiting or restricting our ability to take specific 
actions, such as incurring additional debt, making capital expenditures or declaring dividends. 

If  we  raise  funds  through  additional  strategic  collaborations  or  licensing  arrangements  with  third  parties,  we  may  have  to 
relinquish  valuable  rights  to  our  technologies,  future  revenue  streams,  research  programs  or  product  candidates  or  to  grant 
licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings 
when needed, we may be required to delay, limit, reduce or terminate our drug development or future commercialization efforts 
or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves. 

99 

 
Contractual Obligations 

Our material cash requirements from known contractual obligations as of December 31, 2022 primarily consist of operating and 
finance  lease  liabilities  and  principal  and  interest  payments  under  our  New  Credit  Facility.  Our  total  future  minimum  lease 
payments  for  our  finance  and  operating  leases  are  included  in  Note  12,  Leases,  in  the  Notes  to  Consolidated  Financial 
Statements. The total future undiscounted minimum lease payments, including operating and finance leases, were $14.0 million 
as of December 31, 2022. Our total future minimum principal payments under our New Credit Facility are included in Note 8, 
Debt, in the Notes to Consolidated Financial Statements. The total future minimum principal payments under our New Credit 
Facility were $25.0 million as of December 31, 2022. 

We  enter  into  agreements  in  the  normal  course  of  business  with  third  parties  to  assist  us  with  preclinical,  clinical, 
manufacturing, and other products and services for operating purposes. These agreements are generally cancellable at any time 
by us  upon  reasonable  notice,  and  certain  of  these  agreements  include  termination  rights  subject  to  termination fees  or  wind 
down  costs.  The  exact  amounts  of  such  obligations  are  dependent  on  the  timing  of  termination  and  the  exact  terms  of  the 
relevant agreement and cannot be reasonably estimated. 

We also have obligations to make future payments to third parties that become due and payable on the achievement of certain 
milestones,  including  future  payments  to  third  parties  with  whom  we  have  entered  into  license  agreements.  We  have  not 
included  these  commitments  on  our  balance  sheet  because  the  achievement  and  timing  of  these  milestones  is  not  fixed  and 
determinable. 

In July 2015, we entered into a license agreement with Recepta Biopharma S.A., or Recepta, for the NaPi2b antibody. We refer 
to this license agreement, as amended, as the Recepta License. Under the Recepta License, we paid Recepta an upfront payment 
of $1.0 million and are obligated to pay Recepta up to $65.5 million in development, regulatory and commercial milestones and 
tiered royalties in the low-single digit percentages on net sales of products outside of Brazil until the expiration of the royalty 
term. Upon the expiration of each royalty term in each country for each applicable product, the exclusive licenses granted to 
each party under the Recepta License will become fully-paid  up  and royalty-free. We have incurred  and paid $4.0  million  in 
development milestone payments under the Recepta License. 

In  January  2019,  we  entered  into  a  commercial  license  agreement  with  Synaffix  B.V.,  or  Synaffix,  which  we  amended  and 
restated in November 2021 and February 2022 to expand our relationship with Synaffix. We refer to the amended and restated 
agreement as the Synaffix License. Under the Synaffix License, we have the right to develop, manufacture and commercialize 
ADCs  directed  to  targets  using  Synaffix’s  proprietary  site-specific  conjugation  technology.  We  have  licensed  five  targets  in 
connection with our development programs and collaborations, and we have the right to license up to six additional targets. We 
have paid $6.8 million related to the Synaffix License, comprised of $4.0 million in reservation and license fees, $1.8 million in 
milestone payments and $1.0 million which may be applied to future reservation and license fees, as well as certain portions of 
potential  future  development  milestones.  We  will  be  obligated  to  pay  in  the  range  of  $48.0  million  to  $132.0  million  for 
issuance, development, regulatory and commercial milestones. Upon commencement of commercial sales of any ADC product 
directed to a licensed target, if any, we are required to pay to Synaffix tiered royalties in the low-single digit percentages on net 
sales  of  the  respective  products.  The  Synaffix  License  remains  in  effect  on  a  country-by-country  and  licensed  product-by-
licensed  product  basis  until  the  expiration  of  the  last-to-expire  valid  claim  in  a  patent  licensed  under  the  Synaffix  License 
covering such product in such country. Upon the expiration of the Synaffix License for each licensed product in each country, 
the  licenses  granted  to  us  for  such  product  in  such  country  will  become  fully  paid-up  and  perpetual.  We  may  terminate  the 
Synaffix License in its entirety or on a licensed product-by-licensed product basis at any time. Either party may terminate the 
Synaffix License, subject to a specified notice and cure period, for a breach by the other party of a material provision of the 
agreement or upon an insolvency-related event experienced by the other party. 

Critical Accounting Policies and Significant Judgements and Estimates 

Our  management's  discussion  and  analysis  of  our  financial  condition  and  results  of  operations  are  based  on  our  financial 
statements,  which  have  been  prepared  in  accordance  with  U.S.  generally  accepted  accounting  principles.  The  preparation  of 
these  financial  statements  requires  us  to  make  judgments  and  estimates  that  affect  the  reported  amounts  of  assets,  liabilities, 
revenues, and expenses and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates 
on  historical  experience,  known  trends  and  events,  and  various  other  factors  that  are  believed  to  be  reasonable  under  the 
circumstances. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, 
we  evaluate  our  judgments  and  estimates  in  light  of  changes  in  circumstances,  facts  and  experience. The  effects  of  material 
revisions in estimates, if any, will be reflected in the financial statements prospectively from the date of change in estimates. 

100 

 
 
We  believe  that  our  most  critical  accounting  policies  are  those  relating  to  revenue  recognition  and  accrued  research  and 
development expenses as discussed in the Notes to Consolidated Financial Statements included in this Annual Report on Form 
10-K. 

Revenue Recognition 

We  enter  into  collaboration  agreements  which  are  within  the  scope  of Accounting  Standards  Update  2014-09,  Revenue  from 
Contracts with Customers, or ASC 606, under which we license rights to our technology and certain of our product candidates 
and perform research and development services for third parties. The terms of these arrangements typically include payment of 
one or more of the following: non-refundable, up-front fees; reimbursement of research and development costs; development, 
regulatory and commercial milestone payments; and royalties on net sales of licensed products. 

Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount 
that  reflects  the  consideration  which  the  entity  expects  to  receive  in  exchange  for  those  goods  or  services. To  determine  the 
appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, we perform 
the following five steps: (i) identification of contract(s) with a customer; (ii) determination of whether the promised goods or 
services  are  performance  obligations;  (iii)  measurement  of  the  transaction  price,  including  the  constraint  on  variable 
consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or 
as) we satisfy each performance obligation. We only apply the five-step model to contracts when it is probable that the entity 
will collect consideration it is entitled to in exchange for the goods or services it transfers to the customer. 

The promised good or services in our arrangements typically consist of license rights to our intellectual property and research 
and development services. We also have optional additional items in contracts, which are considered marketing offers and are 
accounted for as separate contracts with the customer  if such  option  is elected by  the  customer,  unless  the option provides  a 
material right which would not be provided without entering into the contract. Performance obligations are promised goods or 
services in a contract to transfer a distinct good or service to the customer. Promised goods or services are considered distinct 
when (i) the customer can benefit from the good or service on its own or together with other readily available resources or (ii) 
the  promised  good  or  service  is  separately  identifiable  from  other  promises  in  the  contract. In  assessing  whether  promised 
goods or services are distinct, we consider factors such as the stage of development of the underlying intellectual property, the 
capabilities  of  the  customer  to  develop  the  intellectual  property  on  their  own  or  whether  the  required  expertise  is  readily 
available. 

We estimate the transaction price based on the amount expected to be received for transferring the promised goods or services 
in  the  contract. The  consideration  may  include  both  fixed  consideration  and  variable  consideration. At  the  inception  of  each 
arrangement that includes variable consideration and at each reporting period, we evaluate the amount of potential payment and 
the likelihood that the payments will be received. We utilize either the most likely amount method or expected amount method 
to estimate the amount expected to be received based on which method better predicts the amount expected to be received. If it 
is probable that a significant revenue reversal would not occur, the variable consideration is included in the transaction price. 

Our contracts often include development and regulatory milestone payments. At contract inception and at each reporting period, 
we  evaluate  whether  the  milestones  are  considered  probable  of  being  reached  and  estimate  the  amount  to  be  included  in  the 
transaction price using the most likely amount method. If it is not probable that a significant revenue reversal would not occur, 
the  associated milestone value  is included in the transaction  price. Milestone payments that  are  not  within  our control or the 
licensee’s  control,  such  as  regulatory  approvals,  are  not  included  in  the  transaction  price. At  the  end  of  each  subsequent 
reporting period, we re-evaluate the probability of achievement of such development milestones and any related constraint, and 
if necessary, adjust our estimate of the overall transaction price. 

For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is 
deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales 
occur,  or  (ii)  when  the  performance  obligation  to  which  some  or  all  of  the  royalty  has  been  allocated  has  been  satisfied  (or 
partially satisfied). 

We allocate the transaction price based on the estimated standalone selling price of the underlying performance obligations or in 
the case of certain variable consideration to one or more performance obligations. We must develop assumptions that require 
judgment  to  determine  the  standalone  selling  price for  each  performance  obligation  identified  in  the  contract. We  utilize  key 
assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in 
negotiating  the  transaction  and  the  estimated  costs  to  complete  the  respective  performance  obligation. Certain  variable 
consideration  is  allocated  specifically  to  one  or  more  performance  obligations  in  a  contract  when  the  terms  of  the  variable 

101 

 
consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated to each performance 
obligation are consistent with the amounts we would expect to receive for each performance obligation. 

For performance obligations consisting of licenses and other promises, we utilize judgment to assess the nature of the combined 
performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time 
and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-
front fees. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and 
related revenue recognition. If the license to our intellectual property is determined to be distinct from the other performance 
obligations identified in the arrangement, we will recognize revenue from non-refundable, up-front fees allocated to the license 
when the license is transferred to the customer and the customer is able to use and benefit from the license. 

Collaborative Arrangements 

We  record  the  elements  of  our  collaboration  agreements  that  represent  joint  operating  activities  in  accordance  with  ASC 
808, Collaborative Arrangements. Accordingly, the elements of the collaboration agreements that represent activities in which 
both parties are active participants and to which both parties are exposed to the significant risks and rewards that are dependent 
on the commercial success of the activities, are recorded as collaborative arrangements. We consider the guidance in ASC 606 
in determining the appropriate treatment for the transactions between us and our collaborators and the transactions between us 
and third parties. Generally, the classification of transactions under the collaborative arrangements is determined based on the 
nature  and  contractual  terms  of  the  arrangement  along  with  the  nature  of  the  operations  of  the  participants.  To  the  extent 
revenue is generated from a collaboration, we will recognize our share of the net sales on a gross basis if we are deemed to be 
the principal in the transactions with customers, or on a net basis if we are instead deemed to be the agent in the transactions 
with customers, consistent with the guidance in ASC 606. 

Accrued Research and Development Expenses 

As  part  of  the  process  of  preparing  our  financial  statements,  we  are  required  to  estimate  our  accrued  expenses  as  of  each 
balance sheet date. This process involves reviewing open contracts and purchase orders, communicating with our personnel to 
identify services that have been performed on our behalf and estimating the level of service performed and the associated cost 
incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service 
providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of 
our accrued expenses as of each balance sheet date based on facts and circumstances known to us at that time. We periodically 
confirm the accuracy of our estimates with the service providers and make adjustments if necessary. The significant estimates in 
our accrued research and development expenses include the costs incurred for services performed by our vendors in connection 
with research and development activities for which we have not yet been invoiced. 

We record our expenses related to research and development activities based upon our estimates of the services received and 
efforts  expended  pursuant  to  quotes  and  contracts  with  vendors  that  conduct  research  and  development  on  our  behalf.  The 
financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment 
flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a 
prepayment of the research and development expense. In accruing service fees, we estimate the time period over which services 
will be performed, enrollment of subjects, number of sites activated and the level of effort to be expended in each period. If the 
actual timing  of the performance of services or the  level of  effort  varies from our estimate,  we  adjust  the  accrued  or prepaid 
expense  balance  accordingly. Although  we  do  not  expect  our  estimates  to  be  materially  different  from  amounts  actually 
incurred,  if  our  estimates  of  the  status  and  timing  of  services  performed  differ  from  the  actual  status  and  timing  of  services 
performed, we may report amounts that are too high or too low in any particular period. To date, there have been no material 
differences  from  our  estimates  to  the  amounts  actually  incurred.  Significant  judgement  is  involved  in  making  the  above 
estimates. 

Recent accounting pronouncements 

See Note 2, Recently Issued Accounting Pronouncements, in the Notes to Consolidated Financial Statements for a description of 
recent accounting pronouncements applicable to our business. 

102 

 
ITEM 7A. 

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK 

Interest Rate Risks 

We are exposed to market risk related to changes in interest rates. As of December 31, 2022, we had cash, cash equivalents and 
marketable securities of $280.7 million. Our primary  exposure to market risk  is interest  rate  sensitivity,  which  is affected by 
changes  in  the  general  level  of  U.S.  interest  rates,  particularly  because  our  investments,  including  cash  equivalents  and 
marketable  securities  are  invested  in  U.S.  Treasury  obligations,  commercial  paper,  corporate  bonds  and  U.S.  government 
agency securities. However, we believe that due to the short-term duration of our investment portfolio and low-risk profile of 
our investments, an immediate 100 basis points change  in the  prime rate  would  not  have  a  material  effect on  the fair market 
value of our investments portfolio. 

The interest rate on our New Credit Facility is sensitive to changes in interest rates. Interest accrues on borrowings under the 
credit facility at a floating rate equal to the greater of (i) 8.50% and (ii) the prime rate plus 5.25%. We do not currently engage 
in any hedging activities against changes in interest rates. As of December 31, 2022, there was $25.0 million outstanding under 
the  New  Credit  Facility,  and  a  potential  change  in  the  associated  interest  rates  would  be  immaterial  to  the  results  of  our 
operations. 

Foreign Currency Exchange Rate Risks 

We are currently not exposed to market risk related to changes in foreign currency exchange rates, but we may contract with 
vendors that are located in Asia and Europe and may be subject to fluctuations in foreign currency rates at that time. 

103 

 
 
ITEM 8. 

FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA 

Mersana Therapeutics, Inc. 

Index to Consolidated Financial Statements 

Report of Independent Registered Public Accounting Firm (PCAOB ID: 42) 
Consolidated Balance Sheets 
Consolidated Statements of Operations and Comprehensive Loss 
Consolidated Statements of Stockholders’ Equity 
Consolidated Statements of Cash Flows 
Notes to Consolidated Financial Statements 

Page 

105 
107 
108 
109 
110 
111 

104 

 
 
 
Report of Independent Registered Public Accounting Firm 

To the Stockholders and the Board of Directors of Mersana Therapeutics, Inc. 

Opinion on the Financial Statements 

We have audited the accompanying consolidated balance sheets of Mersana Therapeutics, Inc. (the Company) as of December 
31,  2022  and  2021,  the  related  consolidated  statements  of  operations  and  comprehensive  loss,  consolidated  statement  of 
stockholders’ equity, and consolidated statement of cash  flows  for  each of the  three  years in the  period  ended  December 31, 
2022, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated 
financial  statements  present  fairly,  in  all  material  respects,  the  financial  position  of  the  Company  at  December  31,  2022  and 
2021, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2022, in 
conformity with U.S. generally accepted accounting principles. 

Basis for Opinion 

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on 
the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company 
Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in 
accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange 
Commission and the PCAOB. 

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the 
audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to 
error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over 
financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting 
but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. 
Accordingly, we express no such opinion. 

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due 
to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, 
evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting 
principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial 
statements. We believe that our audits provide a reasonable basis for our opinion. 

Critical Audit Matter 

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that 
was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that 
are  material  to  the  financial  statements  and  (2)  involved  our  especially  challenging,  subjective,  or  complex  judgments.  The 
communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken 
as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit 
matter or on the accounts or disclosures to which it relates. 

105 

 
 
 
 
 
 
  Accrued & Prepaid Clinical Expenses 

Description of 
the Matter 

As  summarized  in  Note  7  to  the  consolidated  financial  statements,  the  Company’s  accrual  for  clinical 
expenses totaled $14.8 million as of December 31, 2022. In addition, the Company’s Prepaid Expenses 
and  Other  Current  Assets  totaled  $8.5  million,  which  included  amounts  that  were  paid  in  advance  of 
services pursuant to clinical trials as of December 31, 2022. As discussed in Note 2 to the consolidated 
financial statements, the Company is required to estimate clinical costs incurred and related accruals or 
remaining prepaid expenses based on certain information, including actual costs incurred or level of effort 
expended,  as  provided  by  its  vendors.  Payments  for  such  activities  are  based  on  the  terms  of  the 
individual arrangements, which may differ from the pattern of costs incurred. 

Auditing  the  Company’s  accrued  and  prepaid  clinical  expenses  was  complex  and  judgmental,  as  the 
amounts  are  based  on  various  estimates  from  third-party  vendors,  as  well  as  other  inputs  estimated  by 
members  of  management,  such  as,  actual  costs  incurred  but  not  yet  billed,  estimated  project  timelines, 
and the costs associated with these services. Furthermore, due to the duration of the Company’s ongoing 
research  and  development  activities  and  the  timing  of  invoicing  received  from  third  parties,  the  actual 
amounts incurred are not typically known by the date the financial statements are issued.  

How We 
Addressed the 
Matter in Our 
Audit 

To  test  the  accrued  and  prepaid  clinical  expenses,  our  audit  procedures  included,  among  others,  testing 
the  accuracy  and  completeness  of  the  underlying  data  used  to  estimate  the  amounts  recorded.  We 
corroborated the progress of research and development activities through discussion with the Company’s 
research  and  development  personnel  that  oversee  the  research  and  development  projects.  We  also 
inspected the Company’s contracts with third parties and any pending change orders to assess the impact 
on amounts recorded. Additionally, we independently confirmed and/or reviewed information received by 
the Company directly from certain sites and other third parties, which included third parties’ estimates of 
costs incurred to date. We also performed analytical procedures over fluctuations in accrued and prepaid 
clinical expenses by vendor, study, or other significant work order throughout the period subject to audit 
and  inspected  subsequent  invoices  received  from  third  parties  to  assess  the  impact  to  the  accrued  and 
prepaid balances. 

/s/ Ernst & Young LLP 

We have served as the Company’s auditor since 2013. 
Boston, Massachusetts 
February 28, 2023 

106 

 
 
 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 

Consolidated Balance Sheets 

(in thousands, except share and per share data) 

Assets 
Current assets: 

Cash and cash equivalents 
Short-term marketable securities 
Accounts receivable 
Prepaid expenses and other current assets 

Total current assets 
Property and equipment, net 
Operating lease right-of-use assets 
Other assets, noncurrent 
Total assets 
Liabilities and stockholders’ equity 
Current liabilities: 
Accounts payable 
Accrued expenses 
Deferred revenue 
Operating lease liabilities 
Other current liabilities 

Total current liabilities 
Operating lease liabilities, noncurrent 
Long-term debt, net 
Deferred revenue, noncurrent 
Other liabilities, noncurrent 
Total liabilities 
Commitments (Note 15) 
Stockholders' equity 
Preferred stock, $0.0001 par value; 25,000,000 shares authorized; 0 shares issued and 
outstanding at December 31, 2022 and December 31, 2021, respectively 

Common stock, $0.0001 par value; 350,000,000 and 175,000,000 shares authorized at 
December 31, 2022 and December 31, 2021, respectively; 105,144,864 and 73,709,056 shares 
issued and outstanding at December 31, 2022 and December 31, 2021, respectively 
Additional paid-in capital 
Accumulated other comprehensive loss 
Accumulated deficit 
Total stockholders’ equity 
Total liabilities and stockholders’ equity 

December 31, 
2022 

December 31, 
2021 

$ 

$ 

$ 

128,885    $ 
151,827     
30,000     
8,507     
319,219     
3,985     
10,475     
661     
334,340    $ 

13,951    $ 
43,184     
30,610     
2,798     
990     
91,533     
8,575     
24,929     
117,043     
203     
242,283     

177,947  
—  
—  
10,951  
188,898  
1,968  
12,889  
2,356  
206,111   

12,321  
28,716  
3,944  
2,303  
239  
47,523  
11,247   
24,626  
—  
974  
84,370  

—     

—  

11      
746,889     
(152)    
(654,691)    
92,057     
334,340    $ 

7  
572,213  
—  
(450,479) 
121,741  
206,111   

$ 

The accompanying notes are an integral part of these consolidated financial statements. 

107 

 
 
 
 
  
 
  
 
 
 
 
 
 
 
 
  
 
  
 
 
 
 
 
 
 
 
 
 
 
  
 
  
 
 
 
 
 
 
Mersana Therapeutics, Inc. 

Consolidated Statements of Operations and Comprehensive Loss 

(in thousands, except share and per share data) 

Collaboration revenue 
Operating expenses: 

Research and development 
General and administrative 

Total operating expenses 
Other income (expense): 

Interest income 
Interest expense 

Total other income (expense), net 
Net loss 
Other comprehensive loss: 

Unrealized loss on marketable securities 

Comprehensive loss 
Net loss attributable to common stockholders — basic and diluted 
Net loss per share attributable to common stockholders — basic and diluted 
Weighted-average number of shares of common stock used in net loss per share 
attributable to common stockholders — basic and diluted 

Year ended December 31, 
2021 

2020 

2022 

$ 

26,581    $ 

43    $ 

828  

173,385     
56,963     
230,348     

132,013     
36,888     
168,901     

2,883     
(3,328)    
(445)    
(204,212)   $ 

65     
(1,267)    
(1,202)    
(170,060)   $ 

(152)    
(204,364)   $ 
(204,212)   $ 
(2.18)   $ 

—     
(170,060)   $ 
(170,060)   $ 
(2.41)   $ 

$ 

$ 

$ 

$ 

67,036  
21,902  
88,938  

424  
(359) 
65  
(88,045) 

(25) 
(88,070) 
(88,045) 
(1.43) 

  93,654,243      70,580,949      61,485,205  

The accompanying notes are an integral part of these consolidated financial statements. 

108 

 
 
 
 
 
 
  
  
 
 
 
 
  
  
 
 
 
 
  
  
 
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T

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
 
  
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
 
  
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
 
  
 
  
 
 
 
 
 
 
 
 
 
  
 
 
  
 
 
  
 
  
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 

Consolidated Statements of Cash Flows 

(in thousands) 

Cash flows from operating activities 

Net loss 

Adjustments to reconcile net loss to net cash used in operating activities: 
Depreciation 
Net amortization of premiums and discounts on marketable securities 
Stock-based compensation 
Other non-cash items 

Changes in operating assets and liabilities: 

Accounts receivable 
Prepaid expenses and other current assets 
Other assets 
Accounts payable 
Accrued expenses 
Operating lease right-of-use assets 
Operating lease liabilities 
Deferred revenue 
Other liabilities 

Net cash used in operating activities 

Cash flows from investing activities 
Maturities of marketable securities 
Purchase of marketable securities 
Purchase of property and equipment 

Net cash used in investing activities 

Cash flows from financing activities 

Net proceeds from public offering of common stock 
Net proceeds from at-the-market facilities 
Proceeds from exercise of stock options 
Proceeds from purchases of common stock under ESPP 
Payment of employee tax obligations related to vesting of restricted stock units 
Proceeds from issuance of debt, net of issuance costs 
Repayment of debt 
Payments under finance lease obligations 

Net cash provided by financing activities 

Increase (decrease) in cash, cash equivalents and restricted cash 
Cash, cash equivalents and restricted cash, beginning of period 
Cash, cash equivalents and restricted cash, end of period 

Supplemental disclosures of non-cash activities: 

Purchases of property and equipment in accounts payable and accrued expenses 
Debt financing costs in accrued expenses 
Common stock issuance costs in accounts payable and accrued expenses 
Cash paid for interest 
Right-of-use assets obtained in exchange for operating lease liabilities 
Right-of-use assets obtained in exchange for financing lease liabilities 

Year ended December 31, 
2021 

2020 

2022 

$ 

(204,212)   $ 

(170,060)   $ 

(88,045) 

927     
(1,462)    
21,522     
763     

(30,000)    
3,863     
—     
947     
13,594     
2,777     
(2,539)    
143,709     
748     
(49,363)    

97,000     
(247,519)    
(2,197)    
(152,716)    

—     
150,893     
1,331     
1,065     
—     
—     
—     
(272)    
153,017     

855     
—     
18,409     
723     

—     
(2,734)    
(718)    
483     
12,570     
1,829     
(1,827)    
(43)    
525     
(139,988)    

—     
—     
(648)    
(648)    

—     
43,087     
1,837     
640     
(259)    
24,042     
(5,486)    
(215)    
63,646     

(49,062)    
178,425     
129,363    $ 

(76,990)    
255,415     
178,425    $ 

753    $ 
150    $ 
131    $ 
2,463    $ 
298    $ 
—    $ 

—    $ 
—    $ 
—    $ 
429    $ 
3,783    $ 
609    $ 

$ 

$ 
$ 
$ 
$ 
$ 
$ 

1,010  
(86) 
7,172  
148  

—  
(1,950) 
(700) 
942  
7,280  
1,642  
(1,281) 
(828) 
—  
(74,696) 

37,500  
—  
(473) 
37,027  

163,990  
63,036  
3,138  
561  
—  
(197) 
—  
(116) 
230,412  

192,743  
62,672  
255,415  

102  
—  
—  
234  
9,980  
—  

The accompanying notes are an integral part of these consolidated financial statements. 

110 

 
 
 
 
 
  
  
 
  
  
 
 
 
 
 
  
  
 
 
 
 
 
 
 
 
 
 
 
 
  
  
 
  
  
 
 
 
 
 
 
  
  
 
  
  
 
 
 
 
 
 
 
 
 
 
 
  
  
 
 
 
 
  
  
 
  
  
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 

1. Nature of Business and Basis of Presentation 

Mersana  Therapeutics,  Inc.  is  a  clinical-stage  biopharmaceutical  company  focused  on  developing  antibody-drug  conjugates 
("ADCs")  that  offer  a  clinically  meaningful  benefit  for  cancer  patients  with  significant  unmet  need.  The  Company  has 
leveraged  over  20  years  of  industry  learning  in  the ADC  field  to  develop  three  proprietary  and  differentiated  platforms  that 
enable it to develop ADCs that are designed to have  improved efficacy, safety and tolerability relative to  existing ADCs and 
other approved therapies. The Company’s platforms include Dolaflexin and Dolasynthen, each of which deliver the novel and 
proprietary  auristatin  DolaLock  payload,  as  well  as  Immunosynthen,  which  delivers  the novel  stimulator  of  interferon  genes 
("STING") agonist ImmunoLock payload.  

The Company's lead product candidate, upifitamab rilsodotin ("UpRi"), is a first-in-class Dolaflexin ADC targeting NaPi2b, an 
antigen broadly expressed in ovarian cancer and other cancers. The Company is currently evaluating UpRi in platinum-resistant 
ovarian cancer in a single-arm registrational trial, referred to as UPLIFT. The Company is also conducting a placebo-controlled 
Phase 3 clinical trial, referred to as UP-NEXT, to investigate UpRi as a monotherapy maintenance treatment following 
treatment with platinum doublets in recurrent platinum-sensitive ovarian cancer. Additionally, the Company is conducting a 
Phase 1 combination trial, referred to as UPGRADE-A. UPGRADE-A is exploring the combination of UpRi with carboplatin, a 
standard platinum chemotherapy broadly used in the treatment of platinum-sensitive ovarian cancer.  

The Company is also investigating XMT-1660, a B7-H4-directed Dolasynthen ADC, in a Phase 1 clinical trial enrolling patients 
with  solid  tumors,  including  in  breast,  endometrial  and  ovarian  cancers,  and  XMT-2056,  an  Immunosynthen  STING-agonist 
ADC that is designed to target a novel epitope of human epidermal growth factor receptor 2 ("HER2"), in a Phase 1 clinical 
trial  enrolling  previously  treated  patients  with  advanced/recurrent  solid  tumors  expressing  HER2,  including  breast,  gastric, 
colorectal  and  non-small  cell  lung  cancers. The  Company also  has  two  additional  earlier  stage  preclinical  candidates,  XMT-
2068 and XMT-2175, that leverage the Company's Immunosynthen platform. 

The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, the need for 
additional  capital,  risks  of  failure  of  preclinical  studies  and  clinical  trials,  the  need  to  obtain  marketing  approval  and 
reimbursement  for  any  drug product  candidate  that  it  may  identify  and  develop,  the  need  to  successfully  commercialize  and 
gain  market  acceptance  of  its  product  candidates,  dependence  on  key  personnel,  protection  of  proprietary  technology, 
compliance  with  government  regulations,  development  of  technological  innovations  by  competitors,  reliance  on  third  party 
manufacturers and the ability to transition from pilot-scale production to large-scale manufacturing of products. 

The Company has incurred cumulative net losses since inception. The Company’s net loss was $204.2 million, $170.1 million 
and $88.0 million for the years ended December 31, 2022, 2021 and 2020, respectively. The Company expects to continue to 
incur operating losses for at least the next several years. As of December 31, 2022, the Company had an accumulated deficit of 
$654.7 million. The future success of the Company is dependent on, among other factors, its ability to identify and develop its 
product candidates and ultimately upon its ability to attain profitable operations. The Company has devoted substantially all of 
its financial resources and efforts to research and development and general and administrative expense to support such research 
and development. Net losses and negative operating cash flows have had, and will continue to have, an adverse effect on the 
Company’s stockholders’ equity and working capital. 

The Company believes that its currently available funds will be sufficient to fund the Company’s operations through at least the 
next twelve months from the issuance of this Annual Report on Form 10-K. Management’s belief with respect to its ability to 
fund  operations  is  based  on  estimates  that  are  subject  to  risks  and  uncertainties.  If  actual  results  are  different  from 
management’s estimates, the Company may need to seek additional funding. 

The  accompanying  consolidated  financial  statements  have  been  prepared  in  accordance  with  accounting  principles  generally 
accepted  in  the  United  States  ("U.S. GAAP")  and  the  rules  and  regulations  of  the  Securities  and  Exchange  Commission 
("SEC"). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the 
Accounting  Standards  Codification  ("ASC")  and  Accounting  Standards  Updates  ("ASU")  of  the  Financial  Accounting 
Standards Board ("FASB"). 

111 

 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

2. Summary of Significant Accounting Policies 

Principles of Consolidation 

The accompanying consolidated financial statements include those of the Company and its wholly owned subsidiary, Mersana 
Securities Corp. All intercompany balances and transactions have been eliminated. 

Use of Estimates 

The  preparation  of  the  Company's  consolidated  financial  statements  in  conformity  with  U.S.  GAAP  requires  management  to 
make  estimates  and  assumptions  that  affect  the  reported  amounts  of  assets,  liabilities,  equity,  revenue,  expenses  and  related 
disclosure  of  contingent  assets  and  liabilities  at  the  date  of  the  financial  statements  and  reported  amounts  of  revenue  and 
expenses during the reporting period. On an ongoing basis, the Company's management evaluates its estimates which include, 
but  are  not  limited  to,  management's  judgments  with  respect  to  the  identification  of  performance  obligations  and  standalone 
selling prices of those performance obligations within its revenue arrangements, accrued preclinical, manufacturing and clinical 
expenses, valuation of stock-based awards and income taxes. Actual results could differ from those estimates. 

Segment Information 

Operating  segments  are  defined  as  components  of  an  enterprise  about  which  separate  discrete  information  is  available  for 
evaluation by the chief operating decision-maker, or decision making group, in deciding how to allocate resources and assess 
performance. The Company views its operations and manages its business as a single operating segment, which is the business 
of discovering and developing ADCs. 

Research and Development 

Research and development costs are expensed as incurred and include: 

• 

• 

• 

• 

• 

• 

• 

• 

employee-related expenses, including salaries, bonuses, benefits, travel and stock-based compensation expense; 

fees and expenses incurred under agreements with contract research organizations, investigative sites and other entities 
in connection with the conduct of preclinical studies, clinical trials and related services; 

the  cost  of  acquiring,  developing  and  manufacturing  ADC  product  candidates,  clinical  trial  materials  and  other 
research and development materials; 

fees and costs related to regulatory filings and activities; 

costs associated with collaboration agreements and license fees and milestone payments related to license agreements; 

costs  associated  with  creating  and  obtaining  approval  for  the  NaPi2b  companion  or  complementary  diagnostic 
biomarker; 

facilities, depreciation and other expenses, which include direct and allocated expenses for rent, utilities, maintenance 
of facilities, insurance and other supplies; and 

other costs associated with clinical, preclinical, discovery and other research activities. 

Costs for certain development activities, such as preclinical studies, clinical trials and manufacturing development activities, are 
recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical 
site  activations,  and  information  provided  to  the  Company  by  its  vendors  on  their  actual  costs  incurred  or  level  of  effort 
expended. Payments  for  these  activities  are  based  on  the  terms  of  the  individual  arrangements,  which  may  differ  from  the 
pattern of costs incurred, and are reflected on the consolidated balance sheets as prepaid or accrued preclinical, manufacturing 
and clinical expenses. 

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Notes to consolidated financial statements 
(continued) 

Revenue Recognition 

The  Company  enters  into  collaboration  agreements  which  are  within  the  scope  of  ASC  606,  Revenue  from  Contracts  with 
Customers  ("ASC  606"),  under  which  the  Company  licenses  rights  to  its  technology  and  certain  of  the  Company’s  product 
candidates and performs research and development services for third parties. The terms of these arrangements typically include 
payment  of  one  or  more  of  the  following:  non-refundable,  up-front  fees;  reimbursement  of  research  and  development  costs; 
development, regulatory and commercial milestone payments; and royalties on net sales of licensed products. 

Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount 
that  reflects  the  consideration  which  the  entity  expects  to  receive  in  exchange  for  those  goods  or  services. To  determine  the 
appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company 
performs the following five steps: (i) identification of contract(s) with a customer; (ii) determination of whether the promised 
goods or services are performance obligations; (iii) measurement of the transaction price, including the constraint on variable 
consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or 
as) the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is 
probable that the entity will collect consideration to which it is entitled in exchange for the goods or services it transfers to the 
customer. 

The promised good or services in the Company’s arrangements typically consist of license rights to the Company’s intellectual 
property  and  research  and  development  services. The  Company  also  has  optional  additional  items  in  contracts,  which  are 
considered  marketing  offers  and  are  accounted  for  as  separate  contracts  with  the  customer  if  such  option  is  elected  by  the 
customer,  unless  the  option  provides  a  material  right  which  would  not  be  provided  without  entering  into  the 
contract. Performance  obligations  are  promised  goods  or  services  in  a  contract  to  transfer  a  distinct  good  or  service  to  the 
customer. Promised goods or services are considered distinct when (i) the customer can benefit from the good or service on its 
own or together with other readily available resources or (ii) the promised good or service is separately identifiable from other 
promises in the contract. In assessing whether promised goods or services are distinct, the Company considers factors such as 
the  stage  of  development  of  the  underlying  intellectual  property,  the  capabilities  of  the  customer  to  develop  the  intellectual 
property on their own and the availability of the required expertise. 

The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods 
or services in the contract. The consideration may include both fixed consideration and variable consideration. At the inception 
of each arrangement that includes variable  consideration  and  at  each reporting period,  the  Company  evaluates the amount of 
potential payment and the likelihood that the payments will be received. The Company utilizes either the most likely amount 
method or expected value method to estimate the amount expected to be received based on which method better predicts the 
amount of consideration to which the Company will be entitled. If it is probable that a significant revenue reversal would not 
occur, the variable consideration is included in the transaction price. We assessed each of our revenue generating arrangements 
in order to determine whether a significant financing component exists and concluded that a significant financing component 
does not  exist in  any of our arrangements because: (a) the promised consideration  approximates  the  cash selling price of the 
promised goods and services; and (b) timing of payment approximates the transfer of goods and services and performance is 
over a relatively short period of time within the context of the entire term of the contract. 

The  Company’s  contracts  often  include  development  and  regulatory  milestone  payments. At  contract  inception  and  at  each 
reporting  period,  the  Company  evaluates  whether  the  milestones  are  considered  probable  of being  reached  and  estimates  the 
amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue 
reversal would not occur, the associated milestone value is  included in the transaction price. Milestone payments that are not 
within  the  Company’s  control  or  the  licensee’s  control,  such  as  regulatory  approvals,  are  not  included  in  the  transaction 
price. At  the  end  of  each  subsequent  reporting  period,  the  Company  re-evaluates  the  probability  of  achievement  of  such 
development milestones and any related  constraint, and  if necessary, adjusts  its estimate  of  the  overall  transaction price. Any 
such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and 
earnings in the period of adjustment. 

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Notes to consolidated financial statements 
(continued) 

For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is 
deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the 
related  sales  occur,  or (ii)  when  the  performance  obligation  to  which  some  or  all  of  the  royalty  has  been  allocated  has  been 
satisfied  (or  partially  satisfied). To  date,  the  Company  has  not  recognized  any  royalty  revenue  resulting  from  any  of  the 
Company’s collaboration arrangements. 

The  Company  allocates  the  transaction  price  based  on  the  estimated  standalone  selling  price  of  the  underlying  performance 
obligations or in the case of certain variable consideration to one or more performance obligations. The Company must develop 
assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the 
contract. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable 
transactions, pricing considered in negotiating the transaction and the estimated costs to complete the respective performance 
obligation. Certain variable consideration is allocated specifically to one or more performance obligations in a contract when 
the  terms  of  the  variable  consideration  relate  to  the  satisfaction  of  the  performance  obligation  and  the  resulting  amounts 
allocated  to  each  performance  obligation  are  consistent  with  the  amounts  the  Company  would  expect  to  receive  for  each 
performance obligation. 

For performance obligations consisting of licenses and other promises, the Company utilizes judgment to assess the nature of 
the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a 
point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-
refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the 
measure of performance and related revenue recognition. If the license to the Company’s intellectual property is determined to 
be  distinct  from  the  other  performance  obligations  identified  in  the  arrangement,  the  Company  will  recognize  revenue  from 
non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to 
use and benefit from the license. 

The  Company  receives  payments  from  its  customers  based  on  billing  schedules  established  in  each  contract.  Such  billings 
generally have 30-day terms. Up-front payments and fees are recorded as a contract liability (deferred revenue) upon receipt or 
when due until the Company performs its obligations under these arrangements. Amounts are recorded as accounts receivable 
when the right to consideration is unconditional and only the passage of time is required before payment is due. If the right to 
consideration is subject to a condition other than the passage of time, then the amount is recorded as a contract asset until the 
right  to  payment  becomes  unconditional.  In  accordance  with  ASC  606,  the  Company  presents  contract  assets  and  contract 
liabilities on a net basis by customer contract. 

Collaborative Arrangements 

The Company records the elements of its collaboration agreements that represent joint operating activities in accordance with 
ASC 808, Collaborative Arrangements ("ASC 808"). Accordingly, the elements of the collaboration agreements that represent 
activities in which both parties are active participants and to which both parties are exposed to the significant risks and rewards 
that are dependent on the commercial success of the activities, are recorded as collaborative arrangements. The Company also 
considers  the  guidance  in  ASC  606  by  analogy  in  determining  the  appropriate  treatment  for  the  transactions  between  the 
Company  and  its  collaborators  and  the  transactions  between  the  Company  and  third  parties.  Generally,  the  classification  of 
transactions under the collaborative arrangements is determined based on the nature and contractual terms of the arrangement 
along  with  the  nature  of  the  operations  of  the  participants.  To  the  extent  revenue  is  generated  from  a  collaboration,  the 
Company will recognize its share of the net sales on a gross basis if it is deemed to be the principal in the transactions with 
customers,  or  on  a  net  basis  if  it  is  instead  deemed  to  be  the  agent  in  the  transactions  with  customers,  consistent  with  the 
guidance in ASC 606. 

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Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Fair Value Measurements 

Fair  value  is  defined  as  the price  that  would be  received upon  sale of  an  asset  or  paid  to  transfer  a  liability  between market 
participants  at  measurement  dates.  ASC 820, Fair  Value  Measurement,  establishes  a  three-level  valuation  hierarchy  for 
instruments measured at fair value. The hierarchy is based on the transparency of inputs to the valuation of an asset or liability 
as of the measurement date. The three levels are defined as follows: 

Level 1—Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets. 

Level 2—Inputs  to  the  valuation  methodology  include  quoted  prices  for  similar  assets  and  liabilities  in  active  markets,  and 
inputs that are observable for the asset or liability, either directly  or indirectly,  for substantially  the full  term of  the  financial 
instrument. 

Level 3—Inputs to the valuation methodology are unobservable and significant to the fair value measurement. 

Marketable Securities 

The Company’s investment strategy is focused on capital preservation. The Company invests in instruments that meet the credit 
quality standards outlined in the Company’s investment policy. Short-term marketable securities consist of investments in debt 
securities with maturities greater than three months and less than one year from the balance sheet date. The Company classifies 
all  of  its  marketable  securities  as  available-for-sale. Accordingly,  these  investments  are  recorded  at  fair  value.  Fair  value  is 
determined  based  on  quoted  market  prices. Amortization  and  accretion  of  discounts  and  premiums  are  recorded  as  interest 
income within other income (expense), net. Realized gains and losses are included in other income (expense), net.  

The Company assesses its available-for-sale debt securities under the available-for-sale debt security impairment model in ASC 
326, Financial Instruments - Credit Losses, as of each reporting date in order to determine if a portion of any decline in fair 
value below carrying value recognized on its available-for-sale debt securities is the result of a credit loss. The Company 
records credit losses in the consolidated statements of operations and comprehensive loss as a component of other income 
(expense), net, which is limited to the difference between the fair value and the amortized cost of the security. To date, the 
Company has not recorded any credit losses on its available-for-sale debt securities. 

Cash and Cash Equivalents 

The Company considers all highly liquid investments with an original maturity, or a remaining maturity at the time of purchase, 
of three months or less to be cash equivalents. The Company invests excess cash primarily in money market funds, commercial 
paper and government agency securities, which are highly liquid and have strong credit ratings. These investments are subject 
to minimal credit and market risks. Cash and cash equivalents are stated at cost, which approximates market value. 

115 

 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Accounting for Stock-based Compensation 

its  stock-based  compensation 

The  Company  accounts  for 
in  accordance  with  ASC  718,  Compensation—Stock 
Compensation ("ASC  718"). ASC  718  requires  all  stock-based  payments  to  employees,  directors  and  non-employees  to  be 
recognized  as  expense  in  the  statements  of  operations  based  on  their  grant  date  fair  values.  The  Company  estimates  the  fair 
value of options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model requires inputs 
based on certain subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of expected term of 
the award, (c) the risk-free interest rate and (d) expected dividends. The expected stock price volatility is calculated based on a 
period  of  time  commensurate  with  the  expected  term  assumption.  Historically,  due  to  the  lack  of  a  public  market  for  the 
Company's  common  stock  prior  to  completion  of  its  initial  public  offering  and  a  lack  of  company-specific  historical  and 
implied  volatility  data,  the  Company  has  based  its  estimate  of  expected  volatility  on  the  historical  volatility  of  a  group  of 
similar  companies  that  are  publicly  traded.  The  computation  of  expected  volatility  is  based  on  the  historical  volatility  of  a 
representative group of companies with similar characteristics to the Company, including stage of product development and life 
science industry focus. The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, 
Share-Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical 
exercise  data  to  provide  a  reasonable  basis  upon  which  to  estimate  the  expected  term.  During  2022,  the  Company  began  to 
estimate its volatility by using a blend of its stock price history for the length of time it has market data for its stock and the 
historical volatility of similar public companies for the expected term of each grant. For option grants with an expected term for 
which sufficient stock price history for the Company exists, expected stock price volatility is calculated using the average of 
volatilities  for  the  period  of  the  expected  term  prior  to  the  grant  date.  For  options  granted  to  non-employees,  the  Company 
utilizes the contractual term of the option arrangement as the basis for the expected term assumption. The risk-free interest rate 
is based on a treasury instrument whose term is consistent with the expected term of the stock options. The expected dividend 
yield is assumed to be zero as the Company has never paid dividends and has no current plans to do so. 

The Company determines the fair value of each restricted stock unit ("RSU") at its grant date based on the closing market price 
of  the  Company’s  common  stock  on  that  date  or,  if  the  date  of  grant  is  not  a  day  on  which  the  Company's  primary  trading 
market  was  open,  the  immediately  preceding  trading  day.  For  stock-based  compensation  subject  to  service-based  vesting 
conditions,  the  Company  recognizes  stock-based  compensation  expense  equal  to  the  grant  date  fair  value  of  stock-based 
compensation on a straight-line basis over the requisite service period. 

The Company records forfeitures as a cumulative adjustment in the period in which they occur. 

Property and Equipment 

Property  and  equipment  is  stated  at  cost,  less  accumulated  depreciation.  Depreciation  is  computed  using  the  straight-line 
method over the estimated useful life of each asset as follows: 

Computer equipment, office equipment and software 
Laboratory equipment 
Leasehold improvements 

3 years 
5 years 
Shorter of useful life or life of lease 

Upon  retirement  or  sale,  the  cost  of  the  disposed  assets  and  the  related  accumulated  depreciation  are  eliminated  from  the 
balance sheet,  and related gains or losses are  reflected  in the statement  of  operations. There were  no material  sales of  assets 
during the years ended December 31, 2022, 2021 and 2020. 

The Company reviews its long-lived assets for impairment whenever events or changes in business circumstances indicate that 
the carrying amount of the assets may not be fully recoverable. If the Company performs an impairment review to evaluate an 
asset  for  recoverability,  the  Company  compares  forecasts  of  undiscounted  cash  flows  expected  to  result  from  the  use  and 
eventual disposition of the asset to its carrying value. If  the  carrying  amount  of  the asset  exceeds its  estimated undiscounted 
future net cash flows, the Company recognizes an impairment charge in the amount by which the carrying amount of the asset 
exceeds the fair value of the asset. The Company did not recognize impairment charges during the years ended December 31, 
2022, 2021 and 2020. 

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Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Leases 

Consistent  with ASC  842,  Leases,  the  Company  determines  if  an  arrangement  is  a  lease  at  inception.  Operating  leases  are 
included in right-of-use lease assets ("ROU assets"), current portion of lease obligations and long-term lease obligations on the 
Company’s consolidated balance sheets. Assets subject to finance leases are included in property and equipment, and the related 
lease  obligation  is  included  in  other current  liabilities  and  other  long-term  liabilities  on  the  Company’s  consolidated balance 
sheets. Lease assets are tested for impairment in the same manner as long-lived  assets used in  operations.  Lease expense for 
operating leases is recognized on a straight-line basis over the lease term as an operating expense while expense for financing 
leases is recognized as depreciation expense and interest expense using the effective interest method. The Company has elected 
the short-term lease recognition exemption for short-term leases, which allows the Company not to recognize lease liabilities 
and ROU assets on the consolidated balance sheets for leases with an original term of twelve months or less. 

ROU  assets  represent  the  Company’s  right  to  use  an  underlying  asset  for  the  lease  term,  and  lease  obligations  represent  the 
Company’s obligation to make lease payments arising from the lease. Operating lease liabilities and their corresponding ROU 
assets  are  initially  recorded  based  on  the  present  value  of  lease  payments  over  the  expected  remaining  lease  term.  When 
determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the 
option  will  be  exercised.  Certain  adjustments  to  the  ROU  asset  may  be  required  for  items  such  as  incentives  received.  The 
interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental 
borrowing rate to discount lease payments. The incremental borrowing rate reflects the fixed rate at which the Company could 
borrow,  on  a  collateralized  basis,  the  amount  of  the  lease  payments  in  the  same  currency,  for  a  similar  term,  in  a  similar 
economic environment. Prospectively, the Company will adjust the ROU assets for straight-line rent expense, or any incentives 
received and remeasure the lease liability at the net present value using the same incremental borrowing rate that was in effect 
as of the lease commencement or transition date. 

The Company accounts for lease agreements with lease and non-lease components separately. 

Patent Costs 

The  Company  expenses  patent  application  and  related  legal  costs  as  incurred  and  classifies  such  costs  as  general  and 
administrative expenses in the accompanying consolidated statements of operations. 

Income Taxes 

The  Company  accounts  for  income  taxes  in  accordance  with  ASC  740,  Accounting  for  Income  Taxes,  which  provides  for 
deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected 
future tax consequences of events that have been included in the financial statements or tax returns. The Company determines 
its  deferred  tax  assets  and  liabilities  based  on  differences  between  financial  reporting  and  tax  bases  of  assets  and  liabilities, 
which  are  measured  using  the  enacted  tax  rates  and  laws  that  will  be  in  effect  when  the  differences  are  expected  to 
reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some 
or all of the deferred tax assets will not be realized. 

The  Company  recognizes  the effect  of  income  tax  positions  only  if  those  positions  are more  likely  than not  to  be  sustained. 
Recognized  income  tax  positions  are  measured  at  the  largest  amount  that  is  more  likely  than  not  to  be  realized.  Changes  in 
recognition or measurement are reflected in the period in which the change in judgment occurs. 

Comprehensive Income (Loss) 

Comprehensive income (loss) comprises net loss and other  comprehensive  loss. For  the years ended December 31,  2022 and 
2020, other comprehensive income (loss) consisted of changes in unrealized income and loss on marketable securities. For the 
year ended December 31, 2021, comprehensive loss equaled net loss. 

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Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Concentration of Credit Risk and Off-balance Sheet Risk 

Financial instruments that potentially subject the Company to concentrations of credit risk primarily consist of cash equivalents 
and marketable securities. Under its investment policy, the Company limits amounts invested in such securities by credit rating, 
maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. The Company does 
not believe that it is subject to any significant concentrations of credit risk from these financial instruments. The Company has 
no  financial  instruments  with  off-balance  sheet  risk,  such  as  foreign  exchange  contracts,  option  contracts,  or  other  foreign 
hedging arrangements. 

Recently Issued Accounting Pronouncements 

From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies, and the Company 
adopts  such  pronouncements  as  of  the  specified  effective  date.  Unless  otherwise  discussed  below,  the  Company  does  not 
believe that the adoption of recently issued standards has had or may have  a material impact  on  the  Company's consolidated 
financial statements or disclosures. 

118 

Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

3. Collaboration Agreements 

GSK 

On August 6, 2022, the Company entered into a Collaboration,  Option and License Agreement (the "GSK Agreement") with 
GlaxoSmithKline Intellectual Property (No. 4)  Limited ("GSK"), pursuant  to which the Company  granted GSK an  exclusive 
option to obtain an exclusive license (the “Option”) to co-develop and to commercialize products containing XMT-2056 (the 
"Licensed Products"), exercisable within a specified time period (the “Option Period”) after the Company delivers to GSK data 
resulting from completion of dose escalation with enrichment for breast cancer patients in a Phase 1 single-agent clinical trial of 
XMT-2056. GSK’s exercise of the Option may require clearance under the Hart-Scott-Rodino Antitrust Improvements Act of 
1976  (“HSR  Clearance”  and  GSK’s  exercise  of  the  Option  following  any  applicable  HSR  Clearance,  the  “GSK  Option 
Exercise”). Prior to the GSK Option Exercise, the Company will lead and will be responsible for the costs of manufacturing, 
research, and early clinical development related to its XMT-2056 program. After the GSK Option Exercise, if any, GSK may 
elect  to  manufacture  XMT-2056,  and  GSK  and  the  Company  will  co-develop  XMT-2056  aimed  at  the  approval  of  Licensed 
Product(s) in the United States and the European Union, with GSK being responsible for the majority of the development costs. 
GSK  will  be  responsible for all  development  costs  aimed solely  at  gaining  approval outside  the  United  States  and  European 
Union.  

Pursuant to the GSK Agreement, following the GSK Option Exercise and subject to certain exceptions and specified payment 
obligations, the Company’s aggregate shared development costs are capped at a fixed amount, with any amounts in excess to be 
borne by GSK unless and until the Company exercises its option to receive (or bear) a specified share of U.S. profits (or losses) 
for any Licensed Products (“Profit Share Election”). The excess development costs will accrue interest as specified in the GSK 
Agreement and will later  either be repaid by the Company or  offset  against  future regulatory  and sales  milestones or royalty 
payments that may become due to the Company. If the Company exercises its Profit Share Election, the cap on the Company’s 
share of development costs shall no longer apply, and the Company must pay any then-outstanding excess plus accrued interest 
costs. Additionally,  if  the  Company  exercises  its  Profit  Share  Election,  it  may  also  simultaneously  elect  to  co-promote  any 
Licensed Products in the United States. 

Pursuant  to  the  GSK Agreement,  GSK  paid  the  Company  a  non-refundable,  upfront  fee  of  $100.0 million  in  August  2022. 
Following the GSK Option Exercise, if any, GSK is obligated to pay the Company an option exercise payment of $90.0 million 
(the  "Option  Payment").  The  Company  is  eligible  to  receive  future  development,  regulatory,  and  commercial  milestone 
payments up to approximately $1.3 billion and, if the Company does not exercise its Profit Share Election, tiered royalties up to 
the mid-twenty percent range based on global sales of Licensed Products. Included in the aggregate milestone payments amount 
is $30 million that the Company is eligible to earn upon the satisfaction of early clinical development milestones that may occur 
prior to the GSK Option Exercise. If the Company exercises its Profit Share Election, the Company will be eligible to receive 
reduced development, regulatory, and commercial milestone payments and reduced royalty rates on sales outside of the United 
States. Whether or not the Company exercises its Profit Share Election, GSK will be responsible for certain milestone payments 
or  royalties  due  to  specified  third  parties  with  which  the  Company  currently  has  agreements  that  relate  to  the  XMT-2056 
program. 

The GSK Agreement will terminate at the end of the  Option Period  if  GSK  does not  exercise  its  Option.  In the event of  the 
GSK Option Exercise, unless earlier terminated, the GSK Agreement will continue in effect until the date on which the royalty 
term and all payment obligations with respect to all Licensed Products in all countries have expired. 

Accounting Analysis 

The Company assessed the GSK Agreement in accordance with ASC 606 and concluded that the contract counterparty, GSK, is 
a  customer.  The  Company  identified  the  following  two  material  performance  obligations  under  the  GSK  Agreement:  (i) 
development  activities,  including  manufacturing,  research  and  early  clinical  development  activities,  necessary  to  deliver  the 
package of data, information and materials specified in the GSK agreement (the "Development Activities") and (ii) the Option 
to co-develop and to commercialize Licensed Products (the "License Option").  

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Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

The Company concluded that the Development Activities are one distinct performance obligation, as the underlying activities 
are not distinguishable in the context of the contract and are inputs to an integrated development program that will generate data 
and information providing value to GSK  in  determining whether  to  exercise  the Option. The License Option  is  considered a 
material right as the value of the license exceeds the Option Payment, and is therefore a distinct performance obligation.  

In  accordance  with  ASC  606,  the  Company  determined  that  the  initial  transaction  price  under  the  GSK  Agreement  equals 
$100.0 million, consisting of the upfront, non-refundable and non-creditable payment paid by GSK. None of the early clinical 
development milestones that may occur prior to the GSK Option Exercise have been included in the initial transaction price, as 
all  milestone  amounts  were  fully  constrained. As  part  of  its  evaluation  of  the  constraint,  the  Company  considered  numerous 
factors,  including  stage  of  development  and  the  remaining  risks  associated  with  the  development  required  to  achieve  the 
milestones,  as  well  as  whether  the  achievement  of  the  milestones  is  outside  the  control  of  the  Company  or  GSK. The  GSK 
Option  payment  is  excluded  from  the  initial  transaction  price  at  contract  inception  along  with  any  future  development, 
regulatory, and commercial milestone payments (including royalties) following the GSK Option Exercise.  

Consistent with the allocation objective under ASC 606, the Company allocated the $100.0 million fixed upfront payment in the 
transaction  price  to  the  Development  Activities  and  the  License  Option  based  on  each  performance  obligation’s  relative 
standalone selling price. The standalone selling price for the Development Activities was calculated using a cost-plus margin 
approach  for  the  estimated  pre-option  development  timeline.  For  the  standalone  selling  price  of  the  License  Option,  the 
Company utilized an income-based approach which included the following key assumptions: post-option development timeline 
and costs, revenue forecast, discount rates and probabilities of technical and regulatory success.  

The Company is recognizing revenue related to the Development Activities performance obligation over the estimated period of 
the pre-option development using a proportional performance model as the underlying activities are performed. The Company 
measures proportional performance based on the costs incurred relative to the total costs expected to be incurred.  

The Company will defer revenue recognition related to the License Option. If the License Option is exercised and GSK obtains 
an exclusive license, the Company will recognize revenue as it fulfills its obligations under the GSK Agreement. If the Option 
is not exercised, the Company will recognize the entirety of the revenue in the period when the Option expires. 

During the year ended December 31, 2022, the Company recorded collaboration revenue of $2.0 million related to its efforts 
under the GSK Agreement. As of December 31, 2022, the Company had recorded $98.0 million in deferred revenue related to 
the unsatisfied performance obligations under the GSK Agreement. This deferred revenue will be recognized over the 
remaining performance period and classified as current or noncurrent on the consolidated balance sheets based upon the 
expected timing of satisfaction of the performance obligations. 

Janssen 

In February 2022, the Company entered into a research collaboration and license agreement with Janssen Biotech, Inc. 
("Janssen" and such agreement, the "Janssen Agreement") focused on the research, development and commercialization of 
novel ADCs for three oncology targets by leveraging Mersana’s ADC expertise and Dolasynthen platform with Janssen’s 
proprietary antibodies. Upon execution of the Janssen Agreement, the Company received a non-refundable upfront payment of 
$40.0 million from Janssen. Pursuant to the Janssen Agreement, the Company granted Janssen two exclusive, nontransferable, 
worldwide licenses - a research license and a commercialization license (together, the "Janssen Licenses"). The research license 
that forms a part of the Janssen Licenses provides Janssen, on a target-by-target basis, rights under the Company’s technology 
and the Company’s interest in the technology developed jointly through the collaboration solely to conduct Janssen’s activities 
under the research and Chemistry, Manufacturing and Controls ("CMC") plans with respect to each target. The 
commercialization license that forms a part of the Janssen Licenses is a royalty-bearing license granted on a target-by-target 
basis under the Company’s technology and the Company’s interest in the technology developed jointly through the 
collaboration to develop, manufacture, commercialize and otherwise exploit licensed ADCs and any licensed products 
containing licensed ADCs directed toward a target. Janssen may select up to three targets and may substitute each target once 
prior to a substitution deadline. Janssen is not required to pay a fee for its first substitution right, but must pay a one-time fee for 
access to the subsequent substitution rights following its exercise of its second substitution right. 

Pursuant to mutually agreed research and CMC plans, the Company will perform bioconjugation, production development, 
preclinical manufacturing, and certain related research and preclinical development activities, in order to progress the targets 

120 

 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

through investigational new drug application ("IND") submission for further development, manufacture and commercialization 
by Janssen. Janssen will have sole responsibility for IND-enabling studies, IND submission, clinical development, regulatory 
activities and commercialization of the licensed ADCs. Both the Company and Janssen will have equal representation on a Joint 
Research Committee and Joint Manufacturing Committee to oversee the research and CMC activities. The Company estimates 
that its activities under the research plans for the targets will be performed through 2024.  

The Company's CMC activities will be compensated by Janssen at agreed upon rates. Assuming successful development and 
commercialization of all three targets by Janssen, the Company could receive up to an additional $505 million in development 
and regulatory milestones and $530 million in sales milestones as well as tiered mid single-digit to low double-digit royalties on 
aggregate net sales of the ADC products.  

Unless earlier terminated, the Janssen Agreement will expire upon the expiration of the last royalty term for a product under the 
Janssen Agreement. The Janssen Agreement contains customary provisions for termination by either party, including in the 
event of breach of the Janssen Agreement, subject to cure, by Janssen for convenience and by Mersana upon a challenge of the 
licensed patents, and customary provisions regarding the effects of termination.  

Janssen may request that the Company perform clinical manufacturing services under a separate clinical supply agreement. 
Janssen may also request that the Company perform a technology transfer of bioconjugation and manufacturing process 
technology, at Janssen's cost, at an agreed upon rate. 

Accounting Analysis 

The Company assessed the Janssen Agreement in accordance with ASC 606 and concluded that the contract counter party, 
Janssen, is a customer. The Company identified the following seven material performance obligations under the Janssen 
Agreement: (i) exclusive Janssen Licenses and research activities for each of the three designated targets, (ii) CMC activities 
for each of the three designated targets and (iii) the first target substitution right. 

The Company concluded that the Janssen Licenses and research activities are one combined performance obligation for each 
target as the Janssen Licenses are not capable of being distinct from the research activities given their proprietary nature. The 
CMC activities are considered a distinct performance obligation for each target as the activities could be performed by a third-
party provider. The first target substitution right is considered a material right as there is no option exercise fee and, as such, is a 
distinct performance obligation. 

In accordance with ASC 606, the Company determined that the initial transaction price under the Janssen Agreement equals 
$40.0 million, consisting of the upfront, non-refundable and non-creditable payment. None of the development and the 
regulatory milestones were included in the initial transaction price, as all milestone amounts were fully constrained. As part of 
its evaluation of the constraint, the Company considered numerous factors, including stage of development and the remaining 
risks associated with the development required to achieve the milestones, as well as whether the achievement of the milestones 
is outside the control of the Company or Janssen. Any consideration related to sales-based milestones (including royalties) will 
be recognized when the related sales occur as such milestones were determined to relate predominantly to the license granted to 
Janssen and therefore have also been excluded from the transaction price. As of December 31, 2022, the revised total 
transaction price for the Janssen Agreement was $42.0 million. During 2022, the Company revised the estimated transaction 
price by $2.0 million based on the reassessment of the constraint of certain development milestones and the remaining risks 
associated with the development required to achieve the milestones. 

The Company determined that the consideration for CMC activities represents variable consideration. The Company has not 
included potential cost reimbursements within the transaction price as no CMC activities for any of the three targets have been 
initiated. The Company elected to apply the Right to Invoice practical expedient under ASC 606. As such, the Company will 
recognize revenue related to the CMC activities when the services are performed. 

Consistent with the allocation objective under ASC 606, the Company allocated the total transaction price to the Janssen 
Licenses and research activities and first substitution right based on each performance obligation’s relative standalone selling 
price. Each of the standalone selling prices for the Janssen Licenses and research activities and for the first substitution right 
were estimated utilizing an income approach, along with the likelihood of exercise for the substitution right and included the 

121 

 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

following key assumptions: the development timeline, revenue forecast, discount rate and probabilities of technical and 
regulatory success.  

The Company is recognizing revenue related to the Janssen Licenses and research services performance obligation over the 
estimated period of the research services using a proportional performance model. The Company measures proportional 
performance based on the costs incurred relative to the total costs expected to be incurred.  

The Company will recognize revenue related to the first target substitution right over time in congruence with the Janssen 
Licenses and research activities, upon the exercise of the option. If the first target substitution option is not exercised, the 
Company will recognize the entirety of the revenue in the period when the option expires. 

During the year ended December 31, 2022, the Company recorded collaboration revenue of $24.2 million related to its 
performance obligations under the Janssen Agreement. As of December 31, 2022, the Company had recorded $15.8 million in 
deferred revenue related to the Janssen Agreement that will be recognized over the remaining performance period and classified 
as current or noncurrent on the consolidated balance sheets based upon the expected timing of satisfaction of respective 
performance obligations.  

Merck KGaA and affiliates 

Immunosynthen Agreement 

In December 2022, the Company entered into a research collaboration and license agreement with Ares Trading S.A. 
("MRKDG" and such agreement, the "2022 Merck KGaA Agreement"), a wholly owned subsidiary of Merck KGaA, 
Darmstadt, Germany, focused on the research, development and commercialization of novel ADCs for up to two specific target 
antigens by leveraging Mersana’s ADC expertise and Immunosynthen platform with MRKDG’s proprietary antibodies. Within 
45 days of execution of the 2022 Merck KGaA Agreement, the Company received a non-refundable upfront payment of 
$30.0 million. Pursuant to the 2022 Merck KGaA Agreement, the Company granted MRKDG two exclusive, non-transferable, 
worldwide licenses - a research license and a commercialization license (together, the "MRKDG Licenses"). The research 
license that forms a part of the MRKDG Licenses provides MRKDG, on a target-by-target basis, rights under the Company’s 
technology and the Company’s interest in the technology developed jointly through the collaboration solely to conduct 
MRKDG’s activities under the research and CMC plans with respect to each target. The commercialization license that forms a 
part of the MRKDG Licenses is a royalty-bearing license granted on a target-by-target basis under the Company’s technology 
and the Company’s interest in the technology developed jointly through the collaboration to develop, manufacture, 
commercialize and otherwise exploit licensed ADCs and any licensed products containing licensed ADCs directed toward a 
target. 

Pursuant to mutually agreed research and CMC plans, the Company will perform bioconjugation, production development, 
preclinical manufacturing, and certain related research and preclinical development activities, in order to progress the targets 
through IND (or foreign equivalent) submission for further development, manufacture and commercialization by MRKDG. 
MRKDG will have sole responsibility for IND-enabling studies, IND submission, clinical development, regulatory activities 
and commercialization of the licensed ADCs. Both the Company and MRKDG will have equal representation on a Joint 
Research Committee and Joint Manufacturing Committee to oversee the research and CMC activities. The Company estimates 
that its activities under the research plans for the targets will be performed through 2026.  

The Company's CMC activities will be compensated by MRKDG at agreed upon rates. Assuming successful development and 
commercialization of the two targets by MRKDG, the Company could receive up to an additional $200 million in development 
and regulatory milestones and $600 million in sales milestones as well as tiered single-digit to low double-digit royalties on 
aggregate net sales of the ADC products. To date, the Company has not achieved any of the specified milestones.  

Unless earlier terminated, the 2022 Merck KGaA Agreement will expire upon the expiration of the last royalty term for a 
product under the 2022 Merck KGaA Agreement. The 2022 Merck KGaA Agreement contains customary provisions for 
termination by either party, including in the event of breach of the 2022 Merck KGaA Agreement, subject to cure, by MRKDG 
for convenience and by Mersana upon a challenge of the licensed patents, and customary provisions regarding the effects of 
termination.  

122 

 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

MRKDG may request that the Company perform clinical manufacturing services under a separate clinical supply agreement. 
MRKDG may also request that the Company perform a technology transfer of bioconjugation technology, at MRKDG's cost, at 
an agreed upon rate. 

Accounting Analysis 

The Company assessed the 2022 Merck KGaA Agreement in accordance with ASC 606 and concluded that the contract counter 
party, MRKDG, is a customer. The Company identified the following four material performance obligations under the 2022 
Merck KGaA Agreement: (i) exclusive MRKDG Licenses and research activities for each of the two designated targets and (ii) 
CMC activities for each of the two designated targets. 

The Company concluded that the MRKDG Licenses and research activities are one combined performance obligation for each 
target as the MRKDG Licenses are not capable of being distinct from the research activities given their proprietary nature. The 
CMC activities are considered a distinct performance obligation for each target as the activities could be performed by a third-
party provider.  

In accordance with ASC 606, the Company determined that the initial transaction price under the 2022 Merck KGaA 
Agreement equals $32.0 million, consisting of the $30.0 million upfront, non-refundable and non-creditable fee and certain 
near-term discovery milestones. As the $30.0 million upfront fee was not received by the Company as of December 31, 2022, 
the Company recorded an accounts receivable for $30.0 million with a corresponding deferred revenue liability. The Company 
subsequently received this payment in February 2023. The development and the regulatory milestones not included in the 
transaction price were constrained. As part of its evaluation of the constraint, the Company considered numerous factors, 
including stage of development and the remaining risks associated with the development required to achieve the milestones, as 
well as whether the achievement of the milestones is outside the control of the Company or MRKDG. Any consideration related 
to sales-based milestones (including royalties) will be recognized when the related sales occur as such milestones were 
determined to relate predominantly to the license granted to MRKDG and therefore have also been excluded from the 
transaction price. 

The Company determined that the consideration for CMC activities represents variable consideration. The Company has not 
included potential cost reimbursements within the transaction price as no CMC activities for either of the two targets have been 
initiated. The Company elected to apply the Right to Invoice practical expedient under ASC 606. As such, the Company will 
recognize revenue related to the CMC activities when the services are performed. 

Consistent with the allocation objective under ASC 606, the Company allocated the $32.0 million estimated transaction price to 
the MRKDG Licenses and research activities based on each performance obligation’s relative standalone selling price. Each of 
the standalone selling prices for the MRKDG Licenses and research activities were estimated utilizing an adjusted market 
assessment approach, which was established based on comparable transactions. 

The Company is recognizing revenue related to the MRKDG Licenses and research services performance obligation over the 
estimated period of the research services using a proportional performance model. The Company measures proportional 
performance based on the costs incurred relative to the total costs expected to be incurred.  

The Company did not record collaboration revenue related to the 2022 Merck KGaA Agreement during the year ended 
December 31, 2022. As of December 31, 2022, the Company had recorded $30.0 million in deferred revenue related to the 
unsatisfied performance obligations under the 2022 Merck KGaA Agreement. This deferred revenue will be recognized over the 
remaining performance period and classified as current or noncurrent on the consolidated balance sheets based upon the 
expected timing of satisfaction of respective performance obligations. 

Dolaflexin Platform Agreement 

In  June  2014,  the  Company  entered  into  a  collaboration  and  commercial  license  agreement  with  Merck  KGaA  (the  "2014 
Merck KGaA Agreement"). Upon the execution of the 2014 Merck KGaA Agreement, Merck KGaA paid the Company a non-
refundable  technology  access  fee  of  $12.0 million  for  the  right  to  develop  ADCs  directed  to  six  exclusive  targets  over  a 
specified  period  of  time.  No  additional  fees  are  due  when  a  target  is  designated  and  the  commercial  license  to  the  target  is 

123 

 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

granted.  Merck  KGaA  will  be  responsible  for  the  product  development  and  marketing  of  any  products  resulting  from  this 
collaboration.  

Under  the  terms  of  the  2014  Merck  KGaA Agreement,  the  Company  and  Merck  KGaA  develop  research  plans  to  evaluate 
Merck  KGaA's  antibodies  as  ADCs  incorporating  the  Company's  technology.  The  Company  receives  reimbursement  for  its 
efforts  under  the  research  plans.  The  goal  of  the  research  plans  is  to  provide  Merck  KGaA  with  sufficient  information  to 
formally nominate a development candidate and begin IND-enabling studies. 

In  addition  to  the  payments  received  for  research  and  development  activities  performed  on  behalf  of  Merck  KGaA,  the 
Company could be eligible to receive up to a total of $780.0 million in future milestones related to all targets under the 2014 
Merck KGaA Agreement, plus low to mid-single digit royalties on the commercial sales of any resulting products during the 
applicable  royalty  term.  The  total  milestones  are  categorized  as  follows:  development  milestones  $84.0 million;  regulatory 
milestones  $264.0 million;  and  sales  milestones  $432.0 million.  There  are  six  individual  development  milestones  per  target, 
payable  upon  the  completion  of  various  activities,  from  the  delivery  of  ADCs  meeting  defined  specifications,  through  the 
dosing in a Phase 3 clinical trial. There are five regulatory milestones, which are payable upon regulatory approvals for a first 
indication in each of the U.S., European Union and Japanese markets and regulatory approvals for both a second and a third 
indication  in  the  United  States. There  are  three  individual commercial  milestones,  which  are payable  upon  the  attainment  of 
certain defined thresholds for annual net sales. 

All  six  targets  were  designated  prior  to  2018.  The  Company  has  previously  received  $3.0 million  related  to  development 
milestones  under  the  2014  Merck  KGaA Agreement.  There  have  been  no  additional  milestone  payments  in  the  years  ended 
December 31, 2022 or 2021.  

Unless  earlier  terminated,  the  2014  Merck  KGaA  Agreement  will  expire  upon  the  expiration  of  the  last  royalty  term  for  a 
product under the 2014 Merck KGaA Agreement, after which time, Merck KGaA will have a perpetual, royalty-free license, or 
if  Merck  KGaA  does  not  designate  any  ADC  product  candidates  produced  by  the  Company  under  the  2014  Merck  KGaA 
Agreement as preclinical development candidates, upon the expiration of the last to expire research program. Merck KGaA may 
terminate the 2014 Merck KGaA Agreement  in its entirety or  with respect  to any target  for  convenience  upon 60  days' prior 
written  notice.  Each  party  may  terminate  the  2014  Merck  KGaA  Agreement  in  its  entirety  upon  bankruptcy  or  similar 
proceedings  of  the  other  party  or  upon  an  uncured  material  breach  of  the  2014  Merck KGaA Agreement  by  the  other  party. 
However, if such breach only relates to one target, the agreement may only be terminated with respect to such target. 

In May 2018, the Company entered into a Supply Agreement with Merck KGaA (the "2018 Merck KGaA Supply Agreement"). 
Under the terms of the 2018 Merck KGaA Supply Agreement, the Company will provide Merck KGaA preclinical non-good 
manufacturing practice ("non-GMP") ADC drug substance and clinical good manufacturing practice ("GMP") drug substance 
for  use  in  clinical  trials  associated  with  one  of  the  antibodies  designated  under  the  2014  Merck  KGaA  Agreement.  The 
Company receives fees for its efforts under the 2018 Merck KGaA Supply Agreement and reimbursement equal to the supply 
cost.  The  Company  may  also  enter  into  future  supply  agreements  to  provide  clinical  supply  material  should  Merck  KGaA 
pursue clinical development of any other candidates nominated under the 2014 Merck KGaA Agreement. 

Accounting Analysis 

The Company concluded that Merck KGaA is a customer and accounted for the 2014 Merck KGaA Agreement in accordance 
with  ASC  606.  The  Company  identified  the  following  performance  obligations  under  the  2014  Merck  KGaA  Agreement: 
(i) exclusive  license  and  research  services  for  six  designated  targets,  (ii) rights  to  future  technological  improvements  and 
(iii) participation of project team leaders and providing joint research committee services. 

The  Company  has  concluded  that  each  license  for  a  designated  target  is  not  distinct  from  the  research  services  performed 
related  to  the  designated  target  as  Merck  KGaA  cannot  obtain  the  benefit  of  the  license  without  the  related  research 
services. Each license for a designated target and the related services performance obligation is considered distinct from every 
other license for a designated target and related services performance obligation as each research plan is pursued independent of 
every other research plan for other designated targets. 

124 

Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

The  Company  utilizes  the  expected  value  approach  to  estimate  the  amount  of  consideration  related  to  the  payment  of  fees 
associated  with  development  and  research  services. The  Company  utilizes  the  most  likely  amount  approach  to  estimate  any 
development and regulatory milestone payments to be received. As of the date of initial application of ASC 606, there were no 
milestones payments that had not already been received, included in the estimated transaction price. The Company considered 
the stage of development and the remaining risks associated with the remaining development required to achieve the milestone, 
as  well  as  whether  the  achievement  of  the  milestone  is  outside  the  control  of  the  Company  or  Merck  KGaA. The  milestone 
payment  amounts  were  fully  constrained,  as  a  result  of  the  uncertainty  whether  any  of  the  associated  milestones  would  be 
achieved. The Company has determined that any commercial milestones and sales based royalties will be recognized when the 
related sales occur as they were determined to relate predominantly to the license granted and therefore have also been excluded 
from the transaction price. 

The transaction price was allocated to the performance obligations based on the relative estimated standalone selling prices of 
each  performance  obligation  or  in  the  case  of  certain  variable  consideration  to  one  or  more  performance  obligations. The 
estimated standalone selling  prices for  performance  obligations, that  include a license  and  research  services, were  developed 
using  the  estimated  selling  price  of  the  license  and  an  estimate  of  the  overall  effort  to  perform  the  research  service  and  an 
estimated  market  rate  for  research  services.  The  estimated  standalone  selling  price  of  the  licenses  was  established  based  on 
comparable  transactions. The  estimated  standalone  selling  price  for  the  rights  to  future  technological  improvements  was 
developed  based  on  the  estimated  selling  prices  of  a  license  or  rights  received,  as  well  as  considering  the  probability  that 
additional technology would be made available or the probability the counterpart would utilize the technology. The estimated 
standalone  selling  price  for  the  joint  research  committee  services  was  developed  using  an  estimate  of  the  time  and  costs 
incurred to participate in the committees. 

The Company re-evaluates the transaction price in each reporting period and as uncertain events are resolved or other changes 
in  circumstances  occur. As  of  December 31,  2022  and  2021,  the  total  estimated  transaction  price  for  the  2014  Merck  KGaA 
Agreement was $21.3 million. 

The  Company  is  recognizing  revenue  related  to  the  exclusive  license  and  research  and  development  services  performance 
obligation  over  the  estimated  period  of  the  research  and  development  services  using  a  proportional  performance  model. The 
Company measures proportional performance based on the costs incurred relative to the total costs expected to be incurred. To 
the  extent  that  the  Company  receives  fees  for  the  research  services  as  they  are  performed,  these  amounts  are  recorded  as 
deferred  revenue.  Revenue  related  to  future  technological  improvements  and  joint  research  committee  services  will  be 
recognized ratably  over  the  performance  period  (which  in the  case  of  the  joint  research  committee  services  approximate  the 
time  and  cost  incurred  each  period),  which  are  10  and  5  years,  respectively. The  Company  is  continuing  to  reassess  the 
estimated remaining term at each subsequent reporting period. 

As  of  December 31,  2022,  the  Company  has  completed  its  research  service  obligations  associated  with  four  of  the  six 
designated  targets  and  the  joint  research  committee  services.  Collaboration  revenue  recognized  during  the  years  ended 
December 31, 2022 and 2021 was immaterial. During the year ended December, 31 2020, the Company recorded collaboration 
revenue of $0.8 million related to its efforts under the 2014 Merck KGaA Agreement. There was no collaboration revenue or 
corresponding  research  and  development  expense  recognized  during  the  years  ended  December 31,  2022,  2021,  and  2020 
related to the 2018 Merck KGaA Supply Agreement.  

As of each of December 31, 2022 and 2021, the Company had recorded $3.9 million in deferred revenue related to the 2014 
Merck  KGaA  Agreement  and  2018  Merck  KGaA  Supply  Agreement,  in  the  aggregate,  that  will  be  recognized  over  the 
remaining performance period. 

125 

Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Summary of Contract Assets and Liabilities 

The following table presents changes in the balances of the Company's contract liabilities: 

Year ended December 31, 2022 
Contract liabilities: 

Total deferred revenue 

Year ended December 31, 2021 
Contract liabilities: 

Total deferred revenue 

Balance at 
Beginning 
of Period 

Additions 

Deductions 

Balance at 
End of Period 

$ 

3,944    $ 

170,000    $ 

26,291    $ 

147,653  

$ 

3,987    $ 

—    $ 

43    $ 

3,944  

The  Company  did  not  record  any  contract  assets  associated  with  its  collaboration  agreements  as  of  December 31,  2022  and 
December 31, 2021. 

During the years ended December 31, 2022 and 2021 the Company recognized the following revenues as a result of changes in 
the contract liability balances in the respective periods: 

Revenue recognized in the period from: 
Amounts included in the contract liability at the beginning of the period 
Performance obligations satisfied in previous periods 

Other Revenue 

Year ended December 31, 
2021 
2022 

$ 

$ 

43    $ 
—     $ 

43  
—  

The  Company  has  provided  limited  services  for  a  collaborator, Asana  BioSciences,  LLC  ("Asana  Biosciences").  During  the 
year ended December 31, 2022, the Company recognized revenue of $0.3 million related to these services and did not recognize 
revenue related to these services during the years ended 2021 and 2020. The next potential milestone the Company is eligible to 
receive is $2.5 million upon dosing the fifth patient in a Phase 1 clinical trial by Asana BioSciences. While the first patient was 
dosed in April 2022, as of December 31, 2022, the Company considered this next milestone to be fully constrained as there was 
considerable judgment involved in determining whether it is probable that a significant revenue reversal would occur. As part of 
its evaluation of the constraint, the Company considered numerous factors, including the fact that achievement of the milestone 
is outside the control of the Company and there was a high level of uncertainty in achieving this milestone, as the collaborator 
continues to evaluate its candidate in the Phase 1 trial. 

126 

 
 
 
 
 
   
   
   
 
   
   
   
 
 
   
   
   
 
   
   
   
 
   
   
   
 
 
 
  
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

4. Fair Value Measurements 

The following table presents information about the Company's assets measured at fair value on a recurring basis and indicates 
the level within fair value hierarchy of the valuation techniques utilized to determine such value. The Company had no 
marketable securities as of December 31, 2021. 

(in thousands) 
Cash equivalents 

Money market funds 
U.S. government agency securities 

Marketable securities 

U.S. treasury securities 
U.S government agency securities 

December 31, 2022 

Quoted Prices 
in Active 
Markets 
(Level 1) 

Significant 
Other 
Observable 
Inputs 
(Level 2) 

Significant 
Unobservable 
Inputs 
(Level 3) 

Total 

$ 

$ 

50,471    $ 
9,993     
60,464    $ 

50,471    $ 
—     
50,471    $ 

—    $ 
9,993     
9,993    $ 

$  107,810    $  107,810    $ 
—     
$  151,827    $  107,810    $ 

44,017     

—    $ 
44,017     
44,017    $ 

—  
—  
—  

—  
—  
—  

There  were  no  changes  in  valuation  techniques  or  transfers  between  fair  value  measurement  levels  during  the  year  ended 
December 31, 2022. 

Investments classified as Level 1 within the valuation hierarchy generally consist of U.S. treasury securities and money market 
funds, as the fair value is readily determinable based on active daily markets for identical securities. Investments classified as 
Level  2  within  the  valuation  hierarchy  generally  consists  of  U.S.  government  agency  securities,  as  the  fair  value  is  readily 
determinable based on active daily markets for similar securities and other observable inputs. The Company estimates the fair 
values of investments by taking into consideration valuations obtained from third-party pricing sources.  

The  carrying  amounts  reflected  in  the  consolidated  balance  sheets  for  prepaid  expenses  and  other  current  assets,  accounts 
receivable, accounts payable and accrued expenses approximate their fair values due to their short-term nature. 

As of December 31, 2022 and 2021, the carrying value of the Company’s outstanding borrowing under the New Credit Facility 
(as defined in Note 8) approximated fair value (a Level 2 fair value measurement), reflecting interest rates currently available to 
the Company. The New Credit Facility is discussed in more detail in Note 8, Debt. 

127 

 
 
 
 
 
 
  
  
  
 
 
 
  
  
  
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

5. Cash, Cash Equivalents, and Short-Term marketable securities 

Cash and cash equivalents 

The following table summarizes the Company's cash, cash equivalents, and restricted cash as of December 31, 2022 and 2021. 

(in thousands) 

Cash and cash equivalents 
Restricted cash included in other assets, noncurrent 

Year Ended 
December 31, 2022 

  Year ended December 31, 2021 

Beginning 
of period 

End 
of period 

Beginning 
of period 

End 
of period 

$ 

177,947     $ 
478     

128,885     $ 
478     

255,094     $ 
321     

177,947  
478  

Total cash, cash equivalents and restricted cash per statement 
of cash flows 

$ 

178,425     $ 

129,363     $ 

255,415     $ 

178,425  

Marketable securities 

The  following  table  summarizes  the  Company's  marketable  securities  held  at  December 31,  2022.  The  Company  had  no 
marketable securities as of December 31, 2021. 

(in thousands) 
Marketable securities 

U.S. treasury securities 
U.S. government agency securities 

Amortized 
Cost 

December 31, 2022 

Gross 
Unrealized 
Gains 

Gross 
Unrealized 
Losses 

Fair 
Value 

$ 

$ 

107,964    $ 
44,016     
151,980    $ 

7    $ 
24     
31    $ 

(161)   $ 
(23)    
(184)   $ 

107,810  
44,017  
151,827  

All of the Company's marketable securities are due within one year or less. The Company did not realize any gains or losses 
recognized on the sale of marketable securities during the year ended December 31, 2022, and, as a result, the Company did not 
reclassify any amounts out of accumulated comprehensive loss. 

As of December 31, 2022, the Company's debt security portfolio consisted of 17 securities that were in an unrealized loss 
position and had an aggregate fair value of $92.8 million. There were no securities in an unrealized loss position for greater 
than 12 months as of December 31, 2022. The unrealized losses on the Company's marketable securities were caused by market 
interest rate increases. The Company has the intent and ability to hold such securities until recovery. As a result, the Company 
did not record any charges for credit-related impairments for its marketable securities during the year ended December 31, 
2022.  

128 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
  
  
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

6. Property and Equipment 

Property and equipment consists of the following as of December 31, 2022 and 2021: 

(in thousands) 
Laboratory equipment 
Leasehold improvements 
Computers, software, and office equipment 
Total property and equipment at cost 
Less: Accumulated depreciation 

December 31, 
2022 

December 31, 
2021 

$ 

$ 

7,960    $ 
1,943     
1,824     
11,727      
(7,742)    
3,985    $ 

6,725  
1,906  
1,019  
9,650  
(7,682) 
1,968  

Depreciation expense for the years ended December 31, 2022, 2021 and 2020 was $0.9 million, $0.9 million and $1.0 million, 
respectively. 

7. Accrued Expenses 

Accrued expenses consist of the following as of December 31, 2022 and 2021: 

(in thousands) 
Accrued clinical expenses 
Accrued manufacturing expenses 
Accrued payroll and related expenses 
Accrued research and non-clinical expenses 
Accrued professional fees 
Accrued other 

8. Debt 

December 31, 
2022 

December 31, 
2021 

$ 

$ 

14,822    $ 
11,536      
11,558      
2,767     
1,865     
636     
43,184    $ 

7,879  
8,476  
7,319  
3,848  
909  
285  
28,716  

On May 8, 2019, the Company entered into a loan and security agreement (the "Prior Credit Facility") with Silicon Valley Bank 
("SVB"),  pursuant  to  which  the  Company  borrowed  $5.0 million. The  Prior  Credit  Facility  accrued  interest  at  a  floating  per 
annum rate equal to the greater of (i) 4.0% and (ii) 1.50% below the Prime Rate. The Prior Credit Facility had an interest-only 
period through August 31, 2020. 

On August 28, 2020, the Company entered into a second amendment (the "Second Amendment") to the Prior Credit Facility. 
Pursuant to the Second Amendment, the Company drew $5.2 million upon execution of the Second Amendment, the proceeds 
of which were used to repay the Company’s existing balance under the Prior Credit Facility and satisfy its obligations to SVB. 
The  Prior  Credit  Facility,  as  amended  by  the  Second Amendment,  accrued  interest  at  a  floating  per  annum  rate  equal  to  the 
greater of (i) 4.25% and (ii) 1.00% above the Prime Rate.  

129 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

On  October  29,  2021,  the  Company  entered  into  a  loan  and  security  agreement  (the  "New  Credit  Facility")  with  SVB  and 
Oxford ("Oxford" and, together with SVB and the other lenders from time to time a party thereto, the "Lenders"). Pursuant to 
the  New  Credit  Facility,  as  amended  on  February  17,  2022,  October  17,  2022,  and  December  27,  2022,  the  Company  can 
borrow  term  loans  in  an  aggregate  amount  of  $100.0 million,  which  includes  (i)  $40.0 million  available  at  the  option  of  the 
Company in up to four principal advances through June 30, 2023, (ii) an additional $40.0 million in one principal advance, if 
the  Company  reaches  certain  development  milestone  events,  through  September  30,  2023  and  (iii)  an  additional  tranche  of 
$20.0 million, subject to conditional approval from the Lenders. The New Credit Facility is secured by substantially all of the 
Company's personal property owned or later acquired, excluding intellectual property (but including the rights to payments and 
proceeds  from  intellectual  property),  and  a  negative  pledge  on  intellectual  property.  The  Company  drew  $25.0 million  upon 
execution of the New Credit Facility, of which $5.5 million of the proceeds was used to repay the existing balance under the 
Prior Credit Facility and satisfy its obligations to SVB. Upon entering into the New Credit Facility, the Company terminated all 
commitments by SVB to extend further credit under the Prior Credit Facility and all guarantees and security interests granted by 
the Company to SVB under the Prior Credit Facility.  

The New Credit Facility bears interest at a floating per annum rate equal to the greater of (i) 8.50% and (ii) 5.25% above the 
Prime Rate. Interest is payable monthly in arrears on the first day of each month. The Company is obligated to make interest-
only payments through November 1, 2024, followed by equal monthly principal payments and applicable interest through the 
maturity date of October 1, 2026 (the Maturity Date). If certain development milestones are met, then the interest-only period 
will be extended to November 1, 2025. 

The Company is also required to make a final payment to the Lenders equal to 4.25% of the principal amount of the term loans 
then  extended  to  the  Company. This  final  payment  is  accreted  under  the  effective  interest  method  over  the  life  of  each  term 
loan.  The  term  loans  are  secured  by  substantially  all  of  the  Company’s  assets,  except  for  its  intellectual  property  which  is 
subject to a negative pledge, and certain other customary exclusions. 

At the Company’s option, it may prepay the outstanding principal balance of any term loans in whole but not in part, subject to 
a prepayment fee of: (a) 3.0% of the term loans then extended to the Company if the prepayment occurs on or prior to the first 
anniversary of the funding date of such term loan, (b) 2.0% of the term loans then extended to the Company if the prepayment 
occurs after the first anniversary of the funding date of such term loan but on or prior to the second anniversary of the funding 
date of such term loan, or (c) 1.0% of the term loans then extended to the Company if the prepayment occurs after the second 
anniversary of the funding date of such term loan but before the Maturity Date. The New Credit Facility includes customary 
affirmative  and  restrictive  covenants  applicable  to  the  Company.  Affirmative  covenants  include,  among  others,  covenants 
requiring  the  Company  to  maintain  its  corporate  existence  and  governmental  approvals,  deliver  certain  financial  reports, 
maintain  insurance  coverage  and  satisfy  certain  requirements  regarding  deposit  accounts.  The  restrictive  covenants  include, 
among  others,  requirements  relating  to  the  Company’s  ability  to  transfer  collateral,  incur  additional  indebtedness,  engage  in 
mergers or acquisitions, pay dividends or make other  distributions, make  investments, create  liens, sell assets  and  agree  to a 
change in control, in each case subject to certain customary exceptions. 

The Company’s payment obligations under the New Credit Facility are subject to acceleration upon the occurrence of specified 
events of default, which include, but are not limited to, the occurrence of a material adverse change in the Company’s business, 
operations, or financial or other condition. Amounts outstanding upon the occurrence of an event of default are payable upon 
the Lenders' demand and shall accrue interest at an additional rate of 5.0% per annum of the past due amount outstanding. As of 
December 31,  2022,  the  Company  was  in  compliance  with  all  covenants  under  the  New  Credit  Facility.  As  such,  as  of 
December 31,  2022,  the  classification  of the  loan  balance as  stated  on  the balance  sheet  was  based  on  the  timing  of defined 
future payment obligations. 

130 

 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

The following is a summary of obligations under the New Credit Facility as of December 31, 2022: 

(in thousands) 
Total debt 
Less: Current portion of long-term-debt 
Total debt, net of current portion 
Debt financing costs, net of accretion 
Accretion related to final payment 
Long-term debt, net 

As of December 31, 2022, the estimated future principal payments due are as follows: 

(in thousands) 
2023 
2024 
2025 
2026 
Total debt 

December 31, 
2022 

$ 

$ 

$ 

$ 

25,000  
—  
25,000  
(324) 
253  
24,929  

—  
2,083  
12,500  
10,417  
25,000  

Interest expense related to the New Credit Facility for the year ended December 31, 2022 was $3.2 million. The Company did 
not  recognize  any  interest  expense  related  to  the  New  Credit  Facility  during  the  year  ended  December 31,  2021.  Interest 
expense  related  to  the  Prior  Credit  Facility  for  the  year  ended  December 31,  2021  was  $0.8 million.  The  Company  did  not 
recognize any interest expense related to the Prior Credit Facility during the year ended December 31, 2022. 

9. Stockholders’ Equity 

Preferred stock 

As of December 31, 2022, the Company had 25,000,000 shares of authorized preferred stock. No shares of preferred stock have 
been issued. 

At-the-market ("ATM") equity offering program 

In May 2020, the Company established an ATM equity offering program (the "2020 ATM"), pursuant to which it was able to 
offer and sell up to $100.0 million of its common stock from time to time at prevailing market prices. During the year ended 
December 31, 2021, the Company sold 3,961,074 shares of common stock, resulting in net proceeds of $43.1 million. During 
the first quarter of 2022, the Company sold 11,740,210 shares of common stock resulting in net proceeds of $54.8 million under 
the 2020 ATM. As of March 31, 2022, the 2020 ATM had been fully utilized. 

In February 2022, the Company established a new ATM equity offering program (the "February 2022 ATM"), pursuant to which 
it was able to offer and sell up to $100.0 million of its common stock from time to time at prevailing market prices. During the 
year  ended  December 31,  2022,  the  Company  sold  18,757,665  shares  of  common  stock,  resulting  in  net  proceeds  of 
$96.4 million  under  the  February  2022  ATM.  As  of  December 31,  2022,  approximately  $1.6 million  remained  unsold  and 
available for sale under the February 2022 ATM. 

In  November  2022,  the  Company  established  an  additional  ATM  equity  offering  program  (the  "November  2022  ATM"), 
pursuant to which it is able to offer and sell up to $150.0 million of its common stock from time to time at prevailing market 
prices. As of December 31, 2022, the Company had not sold any shares of common stock under the November 2022 ATM. 

131 

 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Follow-on offering 

In June 2020, the Company sold 9,200,000 shares of common stock in an underwritten public offering at a price to the public of 
$19.00 per share. Net proceeds to the Company after deducting fees, commissions and other expenses related to the offering 
were $164.0 million. 

Warrants 

In connection with a 2013 Series A-1 Preferred Stock issuance, the Company granted to certain investors warrants to purchase 
129,491 shares of common stock. The warrants have a $0.05 per share exercise price and a contractual life of 10 years. The fair 
value of these warrants was recorded as a component of equity at the time of issuance. As of December 31, 2022 and 2021 there 
were  outstanding  warrants  to  purchase  22,590  and  39,474  shares  of  common  stock,  respectively.  During  the  year  ended 
December 31, 2022, the Company issued 16,654 shares of common stock upon the net exercise of warrants. 

Exchange warrants 

On  November 26, 2019,  the Company  entered  into  an  exchange  agreement  with  entities  affiliated  with  Biotechnology Value 
Fund,  L.P.  (the  "Exchanging  Stockholders"),  pursuant  to  which  the  Exchanging  Stockholders  exchanged  an  aggregate  of 
2,575,000  shares  of  common  stock  for  warrants  (the  "Exchange  Warrants")  to  purchase  an  aggregate  of  2,575,000  shares  of 
common stock (subject to adjustment in the event of any stock dividends and splits, reverse stock split, merger or consolidation, 
change  of  control,  reorganization  or  similar  transaction,  as  described  in  the  Exchange  Warrants),  with  an  exercise  price  of 
$0.0001 per share. 

In  accordance  with  ASC  Topic  505,  Equity,  the  Company  recorded  the  retirement  of  the  common  stock  exchanged  as  a 
reduction  of  common  shares  outstanding  and  a  corresponding  debit  to  additional  paid-in-capital  at  the  fair  value  of  the 
Exchange Warrants  on  the  issuance  date. While  outstanding,  the  Exchange Warrants  were  classified  as  equity  in  accordance 
with ASC Topic  480,  Distinguishing  Liabilities  from  Equity,  and  the  fair  value of  the  Exchange Warrants  was  recorded  as  a 
credit  to  additional  paid-in  capital  and  is  not  subject  to  remeasurement.  The  Company  determined  that  the  fair  value  of  the 
Exchange  Warrants  is  substantially  similar  to  the  fair  value  of  the  retired  shares  on  the  issuance  date  due  to  the  negligible 
exercise price for the Exchange Warrants. On March 2, 2020, the Exchanging Stockholders exercised the Exchange Warrants in 
full on a net cashless exercise basis, resulting in the issuance of 2,574,971 shares of common stock. 

Common Stock 

At the Company's 2022 Annual Meeting of Stockholders on June 9, 2022, the Company's stockholders approved an amendment 
to  the  Company’s  Fifth Amended  and  Restated  Certificate  of  Incorporation  to  increase  the  number  of  authorized  shares  of 
common stock, $0.0001 par value per share, from 175,000,000 to 350,000,000. This increase became effective upon filing of a 
Certificate of Amendment with the Secretary of State of the State of Delaware on June 9, 2022.  

The holders of the common stock are entitled to one vote for each share held. Common stockholders are not entitled to receive 
dividends, unless declared by the Board of Directors of the Company (the "Board"). 

As of December 31, 2022 and 2021 there were 11,944,664 and 9,199,512, respectively, shares of common stock reserved for 
the exercise of outstanding stock options, restricted stock units ("RSUs") and warrants. 

Stock options 
Restricted stock units 
Warrants 

December 31, 
2022 
  10,051,283     
1,870,791     
22,590     
  11,944,664     

December 31, 
2021 

8,342,429  
817,609  
39,474  
9,199,512  

132 

 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

10. Stock-based Compensation 

Stock incentive plans 

As  of  June  30,  2017,  there  were  3,141,625  stock  options  outstanding  under  the  Company’s  2007  Stock  Incentive  Plan  (the 
"2007 Plan") The 2007 Plan expired in June 2017. Any cancellations or forfeitures of options granted under the 2007 Plan will 
increase the options available under the 2017 Stock Incentive Plan (the "2017 Plan"), as described below. 

In  June  2017  the  Company’s  stockholders  approved  the  2017  Plan. Under  the  2017  Plan  initially,  up  to  2,255,000  shares  of 
common  stock  could  be  granted  to  the  Company's  employees,  officers,  directors,  consultants  and  advisors  in  the  form  of 
options,  RSUs  or  other  stock-based  awards.  The  number  of  shares  of  common  stock  issuable  under  the  2017  Plan  will  be 
cumulatively increased annually on January 1 by the lesser of (a) 4% of the outstanding shares on the immediately preceding 
December 31 or (b) such other amount specified by the Board. The terms of the awards are determined by the Board, subject to 
the provisions of the 2017 Plan. Any cancellations or forfeitures of options granted under the 2007 Plan, which expired in June 
2017, would increase the number of shares that could be granted under the 2017 Plan. On January 1, 2022, the number of shares 
of common stock issuable under the 2017 Plan was increased by 2,948,362 shares. During the year ended December 31, 2022, 
the  Company  granted  3,541,558  RSUs  and  options  to  purchase  shares  of  common  stock  to  employees  and  non-employee 
directors under the 2017 Plan. As of December 31, 2022  there  were  1,501,829 shares  available for  future issuance  under the 
2017 Plan. 

Under the 2017 Plan, both with respect to incentive stock options and nonqualified stock options, the exercise price per share 
will not be less than the fair market value of the common stock on the date of grant, and the vesting period for options granted 
to employees is generally four years. Options granted under the 2017 Plan expire no later than 10 years from the date of grant. 
Options under the 2007 Plan were granted at an exercise price established by the Board (or an authorized committee thereof) 
that was not less than the fair market value of the underlying common stock on the date of grant and subject to such vesting 
provisions determined by the Board (or an authorized committee thereof). The Board may accelerate vesting or otherwise adjust 
the terms of granted options in the case of a merger, consolidation, dissolution, or liquidation of the Company. 

Inducement awards 

From  time  to  time,  the  Company  grants  to  its  employees,  upon  approval  by  the  Board  or  an  authorized  committee  thereof, 
options to purchase shares of common stock and/or RSUs as an inducement to employment in accordance with Nasdaq Listing 
Rule  5635(c)(4).  Prior  to  February  2022,  only  options  were  granted,  and  they  were  granted  outside  of  an  existing  equity 
incentive plan. These options are subject to terms substantially the same as the 2017 Plan.  

In  February 2022,  the Board adopted  the  Company's  2022 Inducement  Stock  Incentive Plan  (the  "Inducement  Plan"),  which 
provides for the grant of nonstatutory options, stock appreciation rights, restricted stock, RSUs and other stock-based awards, 
with  respect  to  an  aggregate  of  2,000,000  shares  of  the  Company's  common  stock  (subject  to  adjustment  as  provided  in  the 
Inducement  Plan).  During  the  year  ended  December 31,  2022,  the  Company  granted  713,025  RSUs  and  options  to  purchase 
shares of common stock to newly hired employees under the Inducement Plan. As of December 31, 2022, there were 1,342,175 
shares available for future issuance under the Inducement Plan.  

As of December 31, 2022 there were options to purchase 757,500 shares of common stock outstanding which were granted as 
inducement awards prior to establishment of the Inducement Plan. 

133 

Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Stock option activity 

A summary of stock option activity is as follows: 

Outstanding at January 1, 2022 
Granted 
Exercised 
Cancelled 
Outstanding at December 31, 2022 
Exercisable at December 31, 2022 

Number 
of Shares 
8,342,429    $ 
2,793,659    $ 
(414,914)   $ 
(669,891)   $ 
  10,051,283    $ 
5,410,541    $ 

Weighted- 
Average 
Exercise Price   
11.25    
5.43    
3.21    
13.09    
9.84   
9.45   

Weighted 
Average 
Remaining 
Contractual 
Term 

Aggregate 
Intrinsic Value 
8,458  

7.2   $ 

7.2   $ 
6.1   $ 

8,197  
6,076  

The weighted-average grant date fair value of options granted during the years ended December 31, 2022, 2021 and 2020, was 
$3.97,  $11.71  and  $7.99  per  share,  respectively.  The  total  intrinsic  value  of  options  exercised  during  the  years  ended 
December 31,  2022,  2021  and  2020,  was  $1.5  million,  $4.3  million,  and  $11.1  million,  respectively. The  aggregate  intrinsic 
value represents the difference between the exercise price and the selling price received by option holders upon the exercise of 
stock options during the period. 

Cash  received  from  the  exercise  of  stock  options  was  $1.3  million,  $1.8  million  and  $3.1  million  for  the years  ended 
December 31, 2022, 2021 and 2020, respectively. 

Restricted stock units 

The  Company  periodically  issues  RSUs  with  a  service  condition  to  certain  officers  and  other  employees  that  typically  vest 
between one year and four years from the grant date. 

A summary of the RSU activity is as follows: 

Unvested at January 1, 2022 
Granted 
Vested 
Forfeited 
Unvested at December 31, 2022 

Weighted-
Average 
Remaining 
Contractual 
Term 

Aggregate 
Intrinsic Value   

Weighted-
Average 
Grant Date 
Fair Value 

1.5   $ 
—    
—    
—    
1.5   $ 

5,086    $ 
  $ 
  $ 
  $ 
10,963    $ 

15.68  
5.70  
15.62  
8.54  
8.55  

Number 
of Shares 

817,609   
1,460,924     
(235,591)    
(172,151)    
1,870,791   

The  total  fair  value  of  RSUs  vested  during  the  years  ended  December 31,  2022,  2021  was  $1.5  million  and  $5.8  million, 
respectively. No RSUs vested during the year ended December 31, 2020. 

134 

 
 
 
 
 
  
 
  
 
  
 
 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Employee stock purchase plan 

During the year ended December 31, 2017, the Board adopted, and the Company's stockholders approved the 2017 employee 
stock purchase plan (the "2017 ESPP"). The Company initially reserved 225,000 shares of common stock for issuance under the 
2017  ESPP,  plus  an  annual  increase,  to  be  added  as  of  January  1st  of  each  year,  equal  to  the  least  of  (i)  450,000  shares  of 
common  stock;  (ii)  one  percent  of  the  number  of  shares  of  common  stock  outstanding  as  of  the  close  of  business  on  the 
immediately preceding December 31st; and (iii) the number of shares of common stock determined by the Board on or prior to 
such date for such year, up to maximum of 4,725,000 shares of common stock in the aggregate. On January 1, 2022, no shares 
were added to the 2017 ESPP. During the years ended December 31, 2022 and 2021 the Company issued 270,774 and 78,253 
shares, respectively, under the 2017 ESPP. As of December 31, 2022, there were 295,791 shares available for issuance under the 
2017 ESPP. 

Stock-based compensation expense 

The Company uses the provisions of ASC 718 to account for all stock-based awards to employees and non-employees. 

Stock-based compensation expense is recognized over the requisite service period, which is generally the vesting period, using 
the straight-line method. 

The  following  table  presents  stock-based  compensation  expense  by  award  type  included  within  the  Company’s  consolidated 
statements of operations and comprehensive loss: 

(in thousands) 
Stock options 
Restricted stock units 
Employee stock purchase plan 
Stock-based compensation expense included in total operating expenses 

Year ended December 31, 
2021 

2020 

2022 

$ 

$ 

15,814    $ 
5,175     
533     
21,522    $ 

14,528    $ 
3,522     
359     
18,409    $ 

5,725  
1,187  
260  
7,172  

The  following  table  presents  stock-based  compensation  expense  as  reflected  in  the  Company’s  consolidated  statements  of 
operations and comprehensive loss: 

(in thousands) 
Research and development 
General and administrative 
Stock-based compensation expense included in total operating expenses 

Year ended December 31, 
2021 

2020 

2022 

$ 

$ 

11,386     $ 
10,136     
21,522    $ 

9,984    $ 
8,425     
18,409    $ 

3,841  
3,331  
7,172  

As of December 31, 2022, there was $30.4 million and $11.6 million of unrecognized stock-based compensation expense 
related to unvested stock options and unvested RSUs, respectively, that is expected to be recognized over a weighted average 
period of 2.0 years and 2.6 years, respectively. 

The fair value of each option award is estimated on the date of grant using the Black–Scholes option pricing model with the 
following weighted average assumptions: 

Risk-free interest rate 
Expected dividend yield 
Expected term (years) 
Expected stock price volatility 

135 

2022 

December 31, 
2021 

2020 

2.1 %  
— %  
5.99  
88 %  

0.9 %  
— %  
6.06  
82 %  

1.2 % 
— % 
6.05 
74 % 

 
 
 
 
 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Expected volatility for the Company’s common stock is determined based on a blended rate of its historical volatility combined 
with the historical volatility of comparable publicly traded companies. The risk-free interest rate is based on the yield of U.S. 
Treasury securities consistent with the expected term  of the  option.  No  dividend  yield was assumed  as  the  Company has not 
historically and does not expect to pay dividends on its common stock. The expected term of the options granted is based on the 
use of the simplified method, in which the expected term is presumed to be the mid-point between the vesting date and the end 
of the contractual term. 

The fair value of RSUs is determined based on the closing price of the Company’s common stock on the date of grant. 

136 

Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

11. Net Loss per Share 

Basic net loss per share of common stock is calculated by dividing the net loss attributable to common stockholders by the 
weighted-average number of shares of common stock outstanding during the period, without further consideration for 
potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common 
stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding for the 
period determined using the treasury stock method. 

For purposes of the diluted net loss per share calculation, stock options, unvested RSUs and warrants to purchase common 
stock are considered to be potentially dilutive securities, but are excluded from the calculation of diluted net loss per share 
because their effect would be anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods 
presented.  

The following table sets forth the outstanding potentially dilutive securities that have been excluded from the calculation of 
diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): 

Stock options 
Unvested restricted stock units 
Warrants 

2022 
  10,051,283      
1,870,791     
22,590      
  11,944,664     

Year ended December 31, 
2021 
8,342,429      
817,609     
39,474      
9,199,512     

2020 

6,112,948   
716,767  
39,474  
6,869,189  

137 

 
 
 
 
 
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

12. Leases 

The Company has an operating lease for its office and lab space in Cambridge, Massachusetts and operating and finance leases 
for certain equipment. In March 2020, the Company entered into the Seventh Amendment to the office and lab space lease ("the 
Office Lease") to extend the term of the lease through March 2026. The Company has an option to extend the lease term of the 
Office Lease for an additional five years. 

On April 5, 2021, the Company entered into an Eighth Amendment to the Office Lease, which granted the Company additional 
office space in its existing building for five years, beginning July 1, 2021, and committed the Company to lease payments of 
$5.0 million over that period (the "Expansion Lease"). Independent from the option under the Office Lease, the Company has 
an option to extend the lease term of the Expansion Lease for an additional five years. The Company’s exercise of the options to 
extend  the  lease  terms  of  both  the  Office  Lease  and  Expansion  Lease  were  not  considered  reasonably  certain  as  of 
December 31, 2022. 

The  Expansion Agreement  is  a  lease  modification  accounted  for  as  a  separate  contract,  because  it  expands  the  scope  of  the 
Office  Lease  and  the  additional  lease  payments  are  commensurate  with  market  rents.  The  Company  assessed  the  lease 
classification of the Expansion Lease as of the date of signing and determined that the Expansion Lease should be accounted for 
as  an  operating  lease.  The  right-of-use  asset  and  corresponding  operating  lease  liability  have  been  calculated  based  on  the 
present value of lease payments over the lease term. The Company determined the appropriate incremental borrowing rate to 
utilize  as  a  discount  rate  by using  a  synthetic  credit  rating  which  was  estimated  based on  an  analysis  of outstanding  debt  of 
companies with similar credit and financial profiles. Since the operating lease is a net lease, as the non-lease components (i.e., 
common area maintenance) are paid separately from rent based on actual costs incurred, such non-lease components were not 
included in the ROU asset and liability and are reflected as an expense in the period incurred. 

The Company had a standby letter of credit agreement for the benefit of its landlord in the amount of $0.5 million in connection 
with the Office Lease and Expansion Lease as of December 31, 2022 and 2021. 

The Company has remaining finance lease terms of one year to five years for certain equipment, some of which include options 
to purchase at fair value.  

The components of lease expense included in research and development and general and administrative expenses in the 
statement of operations were as follows: 

(in thousands) 
Operating lease cost 

Finance lease cost: 
Amortization of right-of-use assets 
Interest on lease liabilities 

Supplemental balance sheet information related to leases was as follows: 

Years ended December 31, 
2021 

2022 

2020 

3,793    $ 

3,502    $ 

2,755  

194    $ 
28     
222    $ 

169    $ 
28     
197    $ 

101  
21  
122  

$ 

$ 

$ 

138 

 
 
 
 
 
  
  
 
  
  
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

Operating leases: 
Operating lease right-of-use assets 
Operating lease liabilities, current 
Operating lease liabilities 

Finance leases: 
Property and equipment, gross 
Property and equipment, accumulated depreciation 
Other liabilities, current 
Other liabilities 

Weighted-average remaining lease term: 
Operating leases 
Finance leases 

Weighted-average discount rate: 
Operating leases 
Finance leases 

Supplemental cash flow information related to leases was as follows: 

(in thousands) 
Cash paid for amounts included in the measurement of lease liabilities: 
Operating cash flows from operating leases 
Operating cash flows from finance leases 
Financing cash flows from finance leases 

$ 

$ 

$ 

$ 

$ 

$ 

$ 

Year ended December 31, 
2021 
2022 

10,475 

2,798 

8,575 

   $ 
   $ 
   $ 

12,889 

2,303 

11,247 

   $ 
1,038 
(539)     $ 
   $ 
240 
   $ 

203 

1,038 
(345)   
239 

449 

3.3 years  
2.0 years  

4.3 years 
4.0 years 

10.8  %  
5.4 %  

10.8 % 
5.4 % 

Year ended December 31, 
2021 
2022 

$ 

$ 

$ 

3,865    $ 
28    $ 
272    $ 

3,241  
28  
215  

Future minimum lease payments under non-cancellable leases as of December 31, 2022 were as follows: 

(in thousands) 
2023 
2024 
2025 
2026 
2027 and thereafter 
Total lease payments 
Present value adjustment 
Present value of lease liabilities 

Operating leases    Finance leases 
$ 

3,857    $ 
4,146     
4,187     
1,310     
—     
13,500     
(2,127)    
11,373    $ 

262  
141  
48  
8  
—  
459  
(15) 
444  

$ 

139 

 
 
 
 
  
 
 
 
 
 
  
 
  
 
 
 
 
 
  
 
  
 
 
  
 
  
 
 
 
  
 
 
 
 
 
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

13. Income Taxes 

For  the  years  ended  December 31,  2022,  2021  and  2020,  the  Company recorded  no  income  tax  benefit  for  the  net  operating 
losses ("NOLs") incurred in each year, due to the Company’s operating losses and a full valuation allowance on deferred tax 
assets. 

A reconciliation of the effective tax rate for the years ended December 31, 2022 and 2021 is as follows: 

Statutory US Federal Rate 
State taxes, net of federal benefit 
Permanent differences 
General business credits 
Stock compensation 
Change in valuation allowance 

2022 

2021 

21.0  %  
5.7 %  
(0.1) %  
4.4 %  
(1.4) %  
(29.6) %  
— %  

21.0 % 
6.3 % 
(0.2) % 
3.8 % 
0.1 % 
(31.0) % 
— % 

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities 
for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s net 
deferred tax assets as of December 31, 2022 and 2021 are as follows: 

(in thousands) 
Deferred tax assets: 

Net operating losses 
R&D capitalization 
Tax credit carryforwards 
Stock-based compensation 
Accrued expenses 
Lease liabilities 
Capitalized licenses 
Deferred revenue 
Depreciation 
Other 

Total gross deferred tax assets 
Valuation allowance 
Net deferred tax assets less valuation allowance 
Deferred tax liabilities 
Right-of-use assets 

Total gross deferred tax liabilities 
Net deferred taxes 

$ 

2022 

2021 

113,981    $ 
40,380     
21,429     
6,522     
3,340     
3,096     
3,077     
1,062     
437     
116     
193,440     
(190,588)    
2,852     

106,055  
—  
12,424  
5,018  
1,874  
3,698  
2,775  
1,076  
493  
71  
133,484  
(130,051) 
3,433  

(2,852)    
(2,852)    
—    $ 

(3,433) 
(3,433) 
—  

$ 

The  Company  has  incurred  NOLs  since  inception.  At  December 31,  2022,  the  Company  had  federal  and  state  NOL 
carryforwards  of  approximately  $432.8  million  and  $365.3  million,  respectively.  Of  the  $432.8  million  of  federal  NOL 
carryforwards, $34.1 million expire at various dates through 2037. The remaining $398.7 million of federal NOL carryforwards 
do not  expire. The  state  NOL  carryforwards  expire  at  various  dates  through  2042. At  December 31,  2022,  the  Company  had 
federal  and  state  research  and  development  tax  credit  carryforwards  of  approximately  $17.4  million  and  $5.1  million, 
respectively, which expire at various dates through 2042. 

140 

 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

As required by ASC 740, management of the Company has evaluated the evidence bearing upon the reliability of its deferred 
tax assets. Based on the weight of available evidence, both positive and negative, management has determined that it is more 
likely  than  not  that  the  Company  will  not  realize  the  benefits  of  all  of  these  assets. Accordingly,  the  Company  recorded  a 
valuation  allowance  of  $190.6  million  and  $130.1  million  at  December 31,  2022  and  December 31,  2021,  respectively.  The 
valuation allowance increased by $60.5 million during the year ended December 31, 2022, primarily a result of the Company's 
current year NOL. 

Utilization  of  the  NOLs  and  research  and  development  tax  credit  carryforwards  may  be  subject  to  a  substantial  annual 
limitation under Section 382 due to ownership change limitations that have occurred previously or that could occur in the future 
in accordance with Section 382, as well as similar state provisions. These ownership changes may limit the amount of NOLs 
and  research  and development  tax  credit  carryforwards  that  can be  utilized  annually  to offset  future  taxable  income and  tax, 
respectively.  If  a  change  in  control  as  defined  by  Section 382  has  occurred  at  any  time  since  the  Company’s  formation, 
utilization of its NOLs or  research and development tax  credit  carryforwards would be subject  to an annual limitation under 
Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by 
the  applicable  long-term  tax-exempt  rate,  which  could  then  be  subject  to  additional  adjustments,  as  required. Any  limitation 
may result in expiration of a portion of the NOLs or research and development tax carryforwards before their utilization. The 
Company  has  determined  that  ownership  changes  have  occurred  in  the  past  and  that  certain  NOLs  and  research  and 
development tax credit carryforwards will be subject to limitation. The amounts presented do not include NOLs or research and 
development tax credit carryforwards that will expire unused due to ownership changes. 

The  Company  applies  the  accounting  guidance  in  ASC  740  related  to  accounting  for  uncertainty  in  income  taxes.  The 
Company’s  reserves  related  to  taxes  are  based  on  a  determination  of  whether,  and  how  much  of,  a  tax  benefit  taken  by  the 
Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies 
present related to the tax benefit. As of December 31, 2022 and 2021, the Company had no unrecognized tax benefits. 

The  Company  has  not  conducted  a  study  of  its  research  and  development  credit  carryforwards.  This  study  may  result  in  an 
adjustment  to  research  and  development  credit  carryforwards;  however,  until  a  study  is  completed  and  any  adjustment  is 
known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the 
Company’s  research  and  development  credits  and,  if  an  adjustment  is  required,  this  adjustment  would  be  offset  by  an 
adjustment to the valuation allowance. Thus, there would be no impact to the balance sheets or statements of operations if an 
adjustment were required. 

Interest  and  penalties  related  to  uncertain  tax  positions  would  be  classified  as  income  tax  expense  in  the  accompanying 
statements  of  operations. As  of  December 31,  2022  and  2021,  the  Company  had  no  accrued  interest  or  penalties  related  to 
uncertain tax positions. 

The Company files income tax returns in the United States federal tax jurisdiction and eight state jurisdictions. The Company 
did not have any foreign operations during the years ended December 31, 2022, 2021 and 2020. The statute of limitations for 
assessment by the Internal Revenue Service and state tax authorities is closed for tax years prior to 2018, although carryforward 
attributes that were generated prior to tax year 2018  may still  be adjusted upon  examination to the  extent  utilized in a future 
period. There are no federal or state audits currently in progress. 

14. Employee Benefit Plan 

The Company has a defined contribution plan established under Section 401(k) of the Internal Revenue Code ("401(k) Plan"), 
which covers substantially all employees. Employees who have attained the age of 21 and have worked more than 1,000 hours 
are eligible to participate in the 401(k) Plan. Employees may contribute up to 95% of eligible pay on a pre–tax basis up to the 
federal annual limits. For the years ended December 2022, 2021, and 2020, the Company made matching contributions equal to 
100%  of  the  employee’s  contributions,  subject  to  a  maximum  of  4%  of  eligible  compensation.  For  the years  ended 
December 31,  2022,  2021  and  2020,  the  Company  recorded  expense  of  $1.1  million,  $0.8  million  and  $0.5  million, 
respectively, related to its contribution to its 401(k) Plan. 

141 

Mersana Therapeutics, Inc. 
Notes to consolidated financial statements 
(continued) 

15. Commitments 

License agreements 

During the years ended December 31, 2022, 2021 and 2020, the Company recorded research and development expense related 
to non-refundable license payments of $1.5 million, $3.1 million, and $0.3 million, respectively.  

During the years ended December 31, 2022, 2021 and 2020, the Company recorded research and development expense related 
to development milestones of $0.7 million, $2.1 million and $0.8 million, respectively. The 2022, 2021, and 2020 development 
milestones were associated with XMT-1660, UpRi, and XMT-1592, respectively. 

See Note 12, Leases, for the Company’s future obligations related to leases as of December 31, 2022. 

142 

ITEM 9. 

None. 

CHANGES  IN  AND  DISAGREEMENTS  WITH  ACCOUNTANTS  ON  ACCOUNTING  AND 
FINANCIAL DISCLOSURE 

ITEM 9A. 

CONTROLS AND PROCEDURES 

Evaluation of Disclosure Controls and Procedures 

We maintain “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange 
Act  of  1934,  as  amended,  or  the  Exchange Act,  that  are  designed  to  ensure  that  information  required  to  be  disclosed  in  the 
reports  that  we  file  or  submit  under  the  Exchange Act  is  (1)  recorded,  processed,  summarized  and  reported  within  the  time 
periods specified in the Securities and Exchange Commission’s rules and forms and (2) accumulated and communicated to our 
management,  including  our  principal  executive  and  principal  financial  officer,  as  appropriate  to  allow  timely  decisions 
regarding required disclosure. Our management recognizes that any controls and procedures, no matter how well designed and 
operated,  can  provide  only  reasonable  assurance  of  achieving  their  objectives  and  our  management  necessarily  applies  its 
judgment in evaluating the cost-benefit relationship of possible controls and procedures. Our disclosure controls and procedures 
are designed to provide reasonable assurance of achieving their control objectives. 

Our  management,  with  the  participation  of  our  principal  executive  officer  and  principal  financial  officer,  has  evaluated  the 
effectiveness of our disclosure controls and procedures as of December 31, 2022, the end of the period covered by this Annual 
Report  on  Form  10-K.  Based  upon  such  evaluation,  our  principal  executive  officer  and  principal  financial  officer  have 
concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of such date. 

Internal Control Over Financial Reporting 

Management’s Report on Internal Control Over Financial Reporting 

Our management is responsible for establishing and maintaining adequate internal control over our financial reporting. Internal 
control over financial reporting is defined in Rules 13a-15(f) and 15d-15(f) promulgated under the Exchange Act as a process 
designed by, or under the supervision of, our principal executive and principal financial officers and effected by our board of 
directors, management and other personnel to provide reasonable assurance regarding the reliability of financial reporting and 
the preparation of financial statements for external purposes in accordance with U.S. generally accepted accounting principles, 
or GAAP. Our internal control over financial reporting includes those policies and procedures that: 

• 

• 

• 

pertain  to  the  maintenance  of  records  that,  in  reasonable  detail,  accurately  and  fairly  reflect  our  transactions  and 
dispositions of our assets; 

provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements 
in  accordance  with  U.S.  GAAP,  and  that  our  receipts  and  expenditures  are  being  made  only  in  accordance  with 
authorizations of our management and directors; and 

provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition 
of our assets that could have a material effect on our financial statements. 

Because  of  its  inherent  limitations,  internal  control  over  financial  reporting  may  not  prevent  or  detect  misstatements. 
Projections  of  any  evaluation  of  effectiveness  to  future  periods  are  subject  to  the  risk  that  controls  may  become  inadequate 
because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. 

Our management assessed the effectiveness of our internal control over financial reporting as of December 31, 2022. In making 
this  assessment,  management  used  the  criteria  set  forth  by  the  Committee  of  Sponsoring  Organizations  of  the  Treadway 
Commission  (COSO)  in  its  2013  Internal  Control  —  Integrated  Framework.  Based  on  our  assessment,  our  management  has 
concluded that, as of December 31, 2022, our internal control over financial reporting is effective based on those criteria. 

Changes in Internal Control over Financial Reporting 

No change in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) 
occurred during the three months ended December 31, 2022 that has materially affected, or is reasonably likely to materially 
affect, our internal control over financial reporting. 

143 

 
ITEM 9B. 

OTHER INFORMATION 

None. 

ITEM 9C. 

DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS 

Not applicable. 

144 

 
 
 
PART III 

ITEM 10. 

DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE 

Other than as noted below, the information required by this item is incorporated by reference to the information set forth in the 
sections  titled  "Proposal  No.  1  –  Election  of  Directors,"  "Executive  Officers,"  and  "Information  Regarding  the  Board  of 
Directors and Corporate Governance" and "Delinquent Section 16(a) Reports," if any, in our definitive proxy statement for our 
2023 annual meeting of stockholders to be filed with the Securities and Exchange Commission within 120 days after the end of 
our fiscal year ended December 31, 2022, or the 2023 Proxy Statement. 

We  post  our  Code  of  Business  Conduct  and  Ethics,  which  applies  to  our  directors,  officers,  and  employees,  including  our 
principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar 
functions,  in  the  “Corporate  Governance”  sub-section  of  the  “Investors  &  Media”  section  (https://ir.mersana.com)  of  our 
corporate website https://mersana.com/. We intend to disclose on our website any amendments to, or waivers from, the Code of 
Business Conduct and Ethics that are required to be disclosed pursuant to the disclosure requirements of Item 5.05 of Form 8-
K. 

ITEM 11. 

EXECUTIVE COMPENSATION 

The information required by this item (other than the information required by Item 402(v) of Regulation S-K) is incorporated 
by reference to the information set forth in the sections titled "Executive Compensation" and "Information Regarding the Board 
of  Directors  and  Corporate  Governance  -  Compensation  Committee  Interlocks  and  Insider  Participation"  in  our  2023  Proxy 
Statement. 

ITEM 12. 

SECURITY  OWNERSHIP  OF  CERTAIN  BENEFICIAL  OWNERS  AND  MANAGEMENT  AND 
RELATED STOCKHOLDER MATTERS 

The information required by this item is incorporated by reference to the information set forth in the sections titled "Security 
Ownership  of  Certain  Beneficial  Owners  and  Management"  and  "Securities  Authorized  for  Issuance  Under  Equity 
Compensation Plans" in our 2023 Proxy Statement. 

ITEM 13. 

CERTAIN  RELATIONSHIPS  AND  RELATED  TRANSACTIONS,  AND  DIRECTOR 
INDEPENDENCE 

The information required by this item is incorporated  by reference  to  the information  set  forth  in the sections  titled "Certain 
Relationships and Related Party Transactions" and "Information Regarding the Board of Directors and Corporate Governance – 
Director Independence" in our 2023 Proxy Statement. 

ITEM 14. 

PRINCIPAL ACCOUNTANT FEES AND SERVICES 

The information required by this item is incorporated by reference to the information set forth in the section titled "Principal 
Accountant Fees and Services" in our 2023 Proxy Statement. 

145 

 
 
ITEM 15. 

EXHIBIT AND FINANCIAL STATEMENT SCHEDULES 

(a)(1) Financial Statements 

PART IV 

Our consolidated financial statements are listed in the "Index to Consolidated Financial Statements" under Part II, Item 8 of this 
Annual Report on Form 10-K. 

(a)(2) Financial Statement Schedules 

All schedules are omitted because they are not required or are not applicable or because the information required is included in 
the consolidated financial statements or the notes thereto. 

(a)(3) Exhibits 

Exhibit 
Number 
3.1 

3.2 

4.1 

4.2 

4.3* 

10.1† 

10.2 

10.3 

10.4 

10.5+ 

10.6+ 

10.7+ 

Description of Exhibit 

Fifth Amended and Restated Certificate of Incorporation, as amended, as of June 9, 2022 (incorporated 
by  reference  to  Exhibit  5.03  to  the  Current  Report  on  Form  8-K  (File  No.  001-38129)  filed  with  the 
Securities and Exchange Commission (the "SEC") on June 10, 2022). 

Amended and Restated Bylaws (incorporated by reference to Exhibit 3.2 to the Current Report on Form 
8-K (File No. 001-38129) filed with the SEC on July 10, 2017). 

Form of Common Stock Warrant (incorporated by reference to Exhibit 4.1 to the Registration Statement 
on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Form of Exchange Warrant (incorporated by reference to Exhibit 4.1 to the Current Report on Form 8-K 
(File No. 001-38129) filed with the SEC on November 27, 2019). 

Description of Securities. 

Form of Indemnification Agreement (incorporated by reference to Exhibit 10.1 to Amendment No. 1 to 
Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 16, 2017). 

Commercial  Lease,  dated  February  24,  2009,  between  Mersana  Therapeutics,  Inc.  and  Rivertech 
Associates II, LLC (incorporated by reference to Exhibit 10.2 to the Registration Statement on Form S-1 
(File No. 333-218412) filed with the SEC on June 1, 2017). 

Seventh  Lease  Extension  and  Modification  Agreement  to  the  Lease  Between  Rivertech  Associates  II 
LLC and Mersana Therapeutics, Inc., dated March 10, 2020, by and between Mersana Therapeutics, Inc. 
and Rivertech Associates II LLC (incorporated by reference to Exhibit 10.1 to the Quarterly Report on 
Form 10-Q (File No. 001-38129) filed with the SEC on May 8, 2020). 

Eighth Lease Modification Agreement to the Lease Between Rivertech Associates II LLC and Mersana 
Therapeutics,  Inc.,  effective  as  of  April  5,  2021,  by  and  between  Mersana  Therapeutics,  Inc.  and 
Rivertech Associates II LLC (incorporated by reference to Exhibit 10.1 to the Quarterly Report on Form 
10-Q (File No. 001-38129) filed with the SEC on May 10, 2021).  

Collaboration  and  Commercial  License  Agreement,  dated  June  23,  2014,  by  and  between  Mersana 
Therapeutics,  Inc.  and  Merck  KGaA  (incorporated  by  reference  to  Exhibit  10.4  to  the  Registration 
Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Amendment  1  to  the  Collaboration  and  Commercial  License  Agreement,  dated  June  1,  2016,  by  and 
between Mersana Therapeutics, Inc. and Merck KGaA (incorporated by reference to Exhibit 10.5 to the 
Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Amendment 2 to the Collaboration and Commercial License Agreement, dated August 12, 2016, by and 
between Mersana Therapeutics, Inc. and Merck KGaA (incorporated by reference to Exhibit 10.6 to the 
Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

146 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
10.8+ 

10.9 

10.10+ 

10.11 

10.12+ 

10.13+ 

10.14+ 

10.15+ 

10.16+ 

10.17+ 

10.18*+ 

10.19+ 

10.20+ 

10.21*+ 

10.22* 

Amendment 3 to the Collaboration and Commercial License Agreement, dated February 28, 2017, by and 
between Mersana Therapeutics, Inc. and Merck KGaA (incorporated by reference to Exhibit 10.7 to the 
Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Amendment  4  to  Collaboration  and  Commercial  License  Agreement  dated  May  15,  2018,  by  and 
between Mersana Therapeutics, Inc. and Merck KGaA (incorporated by reference to Exhibit 10.1 to the 
Quarterly Report on Form 10-Q (File No. 001-38129) filed with the SEC on August 14, 2018). 

License, Development and Commercialization Agreement, dated July 9, 2015, by and between Mersana 
Therapeutics,  Inc.  and  Recepta  Biopharma  S.A.  (incorporated  by  reference  to  Exhibit  10.8  to  the 
Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

First  Amendment  to  the  License,  Development  and  Commercialization  Agreement,  dated  August  19, 
2019,  by  and  between  Mersana  Therapeutics,  Inc.  and  Recepta  Biopharma  S.A.  (incorporated  by 
reference to Exhibit 10.1 to the Quarterly Report on Form 10-Q (File No. 001-38129) filed with the SEC 
on November 6, 2019). 

Second Amendment  to  the  License,  Development  and  Commercialization Agreement, dated  September 
28,  2021,  by  and  between  Mersana  Therapeutics,  Inc.  and  Recepta  Biopharma  S.A.  (incorporated  by 
reference to Exhibit 10.1 to the Quarterly Report on Form 10-Q (File No. 001-38129) filed with the SEC 
on November 9, 2021). 

Agreement Regarding LICR Technology, dated July 9, 2015, by and between Ludwig Institute for Cancer 
Research, Recepta Biopharma S.A. and Mersana Therapeutics, Inc. (incorporated by reference to Exhibit 
10.9  to  the  Registration  Statement  on  Form  S-1  (File  No.  333-218412)  filed  with  the  SEC  on  June  1, 
2017). 

Amended and Restated Commercial License and Option Agreement, dated November 23, 2021, by and 
between  Synaffix  B.V.  and  Mersana  Therapeutics,  Inc.  (incorporated  by  reference  to  Exhibit  10.15  to 
Annual Report on Form 10-K (File No. 001-38129) filed with the SEC on February 28, 2022).  

Amendment  No.  1  to  the  Amended  and  Restated  Commercial  License  and  Option  Agreement,  dated 
February 2, 2022, between  Mersana Therapeutics, Inc. and Synaffix  B.V.  (incorporated by reference to 
Exhibit 10.3 to the Quarterly Report on Form 10-Q (File No. 001-38129) filed with the SEC on May 9, 
2022). 

Research Collaboration and License Agreement, dated February 2, 2022, between Mersana Therapeutics, 
Inc. and Janssen Biotech, Inc. (incorporated by reference to Exhibit 10.2 to the Quarterly Report on Form 
10-Q (File No. 001-38129) filed with the SEC on May 9, 2022). 

Collaboration,  Option  and  License Agreement,  dated  August  6,  2022,  between  Mersana  Therapeutics, 
Inc.  and  GlaxoSmithKline  Intellectual  Property  (No.  4)  Limited  (incorporated  by  reference  to  Exhibit 
10.1  to  the  Quarterly  Report on  Form 10-Q  (File  No.  001-38129)  filed  with  the  SEC  on  November  7, 
2022). 

Collaboration  and  Commercial  License  Agreement,  dated  December  22,  2022,  between  Mersana 
Therapeutics, Inc. and Ares Trading S.A.  

Loan  and  Security Agreement,  dated  October  29,  2021,  by  and  between  Oxford  Finance  LLC,  Silicon 
Valley  Bank  and  Mersana  Therapeutics,  Inc.  (incorporated  by  reference  to  Exhibit  10.14  to  Annual 
Report on Form 10-K (File No. 001-38129) filed with the SEC on February 28, 2022). 

First Amendment  to  Loan  and  Security Agreement, dated February 17,  2022,  between  Oxford  Finance 
LLC,  the  Lenders  named  therein  including  Silicon  Valley  Bank,  and  Mersana  Therapeutics,  Inc. 
(incorporated by reference to Exhibit 10.4 to the Quarterly Report on Form 10-Q (File No. 001-38129) 
filed with the SEC on May 9, 2022). 

Second Amendment to Loan and Security Agreement, dated October 17, 2022, between Oxford Finance 
LLC, the Lenders named therein including Silicon Valley Bank, and Mersana Therapeutics, Inc. 

Third Amendment to Loan and Security Agreement, dated December 27, 2022, between Oxford Finance 
LLC, the Lenders named therein including Silicon Valley Bank, and Mersana Therapeutics, Inc. 

147 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
10.23 

10.24† 

10.25† 

10.26† 

10.27† 

10.28† 

10.29† 

10.30† 

10.31† 

10.32† 

10.33† 

10.34† 

10.35† 

10.36† 

10.37† 

10.38† 

10.39† 

Sales  Agreement,  dated  November  7,  2022,  between  Mersana  Therapeutics,  Inc.  and  Cowen  and 
Company, LLC (incorporated by reference to Exhibit 1.1 to the Current Report on Form 8-K (File No. 
001-38129) filed with the SEC on November 7, 2022). 

Amended  and  Restated Offer Letter,  by  and  between  Mersana Therapeutics,  Inc.  and Anna  Protopapas, 
dated March 17, 2017 (incorporated by reference to Exhibit 10.16 to the Registration Statement on Form 
S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Amended  and  Restated  Offer  Letter,  by  and  between  Mersana  Therapeutics,  Inc.  and  Timothy  B. 
Lowinger, dated March 8, 2017 (incorporated by reference to Exhibit 10.18 to the Registration Statement 
on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Offer  Letter,  by  and between  Mersana Therapeutics,  Inc.  and  Brian  DeSchuytner,  dated June  10,  2019 
(incorporated by reference to Exhibit 10.3 to the Quarterly Report on Form 10-Q (File No. 001-38129) 
filed with the SEC on May 8, 2020). 

Offer  Letter,  by  and  between  Mersana  Therapeutics,  Inc.  and  Arvin  Yang,  dated  November  5,  2020 
(incorporate  by reference  to Exhibit  10.2  to  the  Quarterly  Report  on  Form  10-Q  (File  No.  001-38129) 
filed with the SEC on May 10, 2021).  

Offer Letter, dated March 5, 2021, by  and between Mersana Therapeutics,  Inc.  and Alejandra  Carvajal 
(incorporated by reference to Exhibit 10.5 to the Quarterly Report on Form 10-Q (File No. 001-38129) 
filed with the SEC on May 9, 2022). 

Offer Letter, dated  June 15, 2021,  between  Mersana Therapeutics,  Inc.  and Tushar Misra  (incorporated 
by reference to Exhibit 10.6 to the Quarterly Report on Form 10-Q (File No. 001-38129) filed with the 
SEC on May 9, 2022). 

2007 Stock Incentive Plan, as amended (incorporated by  reference  to  Exhibit 10.19  to  the  Registration 
Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 1, 2017). 

Form  of  Incentive  Stock  Option  under  the  2007  Stock  Incentive  Plan  (incorporated  by  reference  to 
Exhibit 10.20 to the the Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC 
on June 1, 2017). 

Form of Nonqualified Stock Option  under the  2007 Stock Incentive  Plan  (incorporated by reference to 
Exhibit 10.21 to the the Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC 
on June 1, 2017). 

2017  Stock  Incentive  Plan  (incorporated  by  reference  to  Exhibit  10.22  to  Amendment  No.  1  to 
Registration Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 16, 2017). 

Form  of  Incentive  Stock  Option  under  the  2017  Stock  Incentive  Plan  (incorporated  by  reference  to 
Exhibit 10.23 to Amendment No. 1 to Registration Statement on Form S-1 (File No. 333-218412) filed 
with the SEC on June 16, 2017). 

Form of Nonqualified Stock Option  under the  2017 Stock Incentive  Plan  (incorporated by reference to 
Exhibit 10.24 to Amendment No. 1 to Registration Statement on Form S-1 (File No. 333-218412) filed 
with the SEC on June 16, 2017). 

Form of Restricted Stock Unit under the 2017 Stock Incentive Plan (incorporated by reference to Exhibit 
10.1 to the Quarterly Report on Form 10-Q (File No. 333-38129) filed with the SEC on August 6, 2021). 

2022 Inducement Stock Incentive Plan (incorporated by reference to Exhibit 10.28 to the Annual Report 
on Form 10-K (File No. 001-38129) filed with the SEC on February 28, 2022). 

Form  of  Inducement  Restricted  Stock  Unit  under  the  2022  Inducement  Stock  Incentive  Plan 
(incorporated by  reference  to  Exhibit  10.29  to  the Annual Report  on  Form  10-K  (File  No.  001-38129) 
filed with the SEC on February 28, 2022). 

Form of Non-statutory Stock Option under the 2022 Inducement Stock Incentive Plan (incorporated by 
reference to Exhibit 10.30 to the Annual Report on Form 10-K (File No. 001-38129) filed with the SEC 
on February 28, 2022). 

10.40*† 

2017 Employee Stock Purchase Plan, as amended 

148 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
10.41† 

10.42*† 

21.1* 

23.1* 

31.1* 

31.2* 

32.1** 

97*† 

101.INS* 

101.SCH* 

101.CAL* 

101.DEF 

101.LAB* 

101.PRE* 

104* 

2017 Cash Bonus Plan (incorporated by reference to Exhibit 10.26 to Amendment No. 1 to Registration 
Statement on Form S-1 (File No. 333-218412) filed with the SEC on June 16, 2017). 

Non-Employee Director Compensation Policy, effective as of December 1, 2022. 

Subsidiaries of Mersana Therapeutics, Inc. 

Consent of Ernst & Young LLP, independent registered public accounting firm. 

Certification  of  Principal  Executive  Officer  pursuant  to  Rules  13a-14(a)  and  15d-14(a)  under  the 
Securities Exchange Act of 1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. 

Certification  of  Principal  Financial  Officer  pursuant  to  Rules  13a-14(a)  and  15d-14(a)  under  the 
Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.  

Certification of Principal Executive Officer and Principal Financial Officer pursuant to 18 U.S.C. Section 
1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. 

Clawback Policy 

Inline XBRL Instance Document 

Inline XBRL Taxonomy Extension Schema Document 

Inline XBRL Taxonomy Extension Calculation Linkbase Document 

Inline XBRL Taxonomy Extension Definition Linkbase Document 

Inline XBRL Taxonomy Extension Label Linkbase Document 

Inline XBRL Taxonomy Extension Presentation Linkbase Document 

Cover  Page  Interactive  Data  File  -  the  cover  page  XBRL  tags  are  embedded  within  the  Inline  XBRL 
document (included in Exhibit 101). 

* 
** 

† 
+ 

Filed herewith. 
The certification attached as Exhibit 32.1 accompanying this Annual Report on Form 10-K is not deemed filed with 
the Securities and Exchange Commission and is not to be  incorporated by reference into any filing of the Company 
under  the  Securities Act  of  1933,  as  amended,  or  the  Securities  Exchange Act  of  1934,  as  amended,  whether  made 
before  or  after  the  date  of  this  Annual  Report  on  Form  10-K,  irrespective  of  any  general  incorporation  language 
contained in such filing. 
Indicates a management contract or compensatory plan. 
Portions of this exhibit have been omitted pursuant to Item 601(b)(10)(iv) of Regulation S-K. 

ITEM 16. 

FORM 10-K SUMMARY 

None. 

149 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Company has duly caused this 
report to be signed on its behalf by the undersigned, thereunto duly authorized. 

SIGNATURES 

Date: February 28, 2023 

Mersana Therapeutics, Inc. 

/s/ Anna Protopapas 

Anna Protopapas 
President and Chief Executive Officer 

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following 
persons on behalf of the registrant and in the capacities and on dates indicated. 

Signature 

/s/ ANNA PROTOPAPAS 

Anna Protopapas 

/s/ BRIAN DESCHUYTNER 
Brian DeSchuytner 

/s/ ASHISH MANDELIA 
Ashish Mandelia 

/s/ DAVID MOTT 

David Mott 

/s/ LAWRENCE M. ALLEVA 

Lawrence M. Alleva 

/s/ WILLARD H. DERE, M.D. 
Willard H. Dere, M.D. 

/s/ ALLENE M. DIAZ 
Allene M. Diaz 

/s/ ANDREW A. F. HACK 
Andrew A. F. Hack, M.D., Ph.D. 

/s/ KRISTEN HEGE 
Kristen Hege, M.D. 

/s/ MARTIN H. HUBER, M.D. 
Martin H. Huber, M.D. 

Title 

  President,  Chief  Executive  Officer  and  Director 

(Principal Executive Officer) 

  Senior Vice President, Chief Financial Officer (Principal 

Financial Officer) 

Date 
  February 28, 2023 

  February 28, 2023 

  Vice President, Controller (Principal Accounting Officer)   February 28, 2023 

  February 28, 2023 

  February 28, 2023 

  February 28, 2023 

  February 28, 2023 

  February 28, 2023 

  February 28, 2023 

  February 28, 2023 

  Chairman of the Board 

  Director 

  Director 

  Director 

  Director 

  Director 

  Director 

150 

 
 
 
 
 
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
 
 
   
   
 
EXECUTIVE OFFICERS 

DIRECTORS 

CORPORATE INFORMATION 

Anna Protopapas 
Chief Executive Officer and 
President, Director 

Brian DeSchuytner 
Senior Vice President,  
Chief Financial Officer 

Alejandra Carvajal 
Senior Vice President,  
Chief Legal Officer 

Timothy B. Lowinger, Ph.D 
Senior Vice President,  
Chief Science and Technology 
Officer 

Tushar Misra, Ph.D. 
Senior Vice President,  
Chief  Manufacturing Officer 

Arvin Yang, M.D., Ph.D. 
Senior Vice President,  
Chief Medical Officer

David Mott 
Chair of the Board of Directors;  
Private Investor, Mott Family 
Capital   

Transfer Agent and Registrar 
Computershare Trust Company, N.A. 
150 Royall Street 
Canton, MA 02021 

Anna Protopapas 
Chief Executive Officer and 
President  

Lawrence M. Alleva 
Former Partner, 
PricewaterhouseCoopers LLP 

Willard H. Dere, M.D 
Professor Emeritus of Internal 
Medicine, University of Utah 

Allene M. Diaz 
Commercial Strategy and Portfolio 
Management Consultant,  
AMD Consulting 

Andrew A. F. Hack, M.D., Ph.D. 
Managing Director,  
Bain Capital Life Sciences 

Kristen Hege, M.D.  
Former Senior Vice President, Early 
Clinical Development, Hematology/ 
Oncology & Cell Therapy,  
Bristol Myers Squibb Company 

Martin Huber, M.D. 
President and Head of R&D,  
Xilio Therapeutics, Inc. 

Form 10-K Requests 
Our Annual Report on Form 10-K 
for the fiscal year ended 
December 31, 2022 has been filed 
with the Securities and Exchange 
Commission, and additional 
copies are available without 
charge upon written request by 
contacting us at our Corporate 
Headquarters, attention: Secretary.  

Corporate Headquarters 
840 Memorial Drive 
Cambridge, Massachusetts 02139  

Common Stock Data 
Nasdaq Global Select Market 
Symbol: MRSN 

Investor Relations  
Jason Fredette 
SVP, Investor Relations & 
Corporate Communications 
(617) 498-0020 
Jason.Fredette@mersana.com 

Annual Meeting  
Our annual meeting of stockholders 
will be held on Thursday, June 8, 
2023 at 10:00 a.m. Eastern Time via 
the internet at 
www.virtualshareholdermeeting.com/
MRSN2023. 

Independent Registered Public 
Accounting Firm  
Ernst & Young LLP 
Boston, Massachusetts