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Mustang Bio, Inc.

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FY2022 Annual Report · Mustang Bio, Inc.
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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-K

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

For the Fiscal Year Ended  December 31, 2022

or

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

For the Transition Period from                    to                   .

Commission File No. 001-38191

MUSTANG BIO, INC.
(Exact Name of Registrant as Specified in its Charter)

Delaware
(State or Other Jurisdiction of Incorporation or Organization)

47-3828760
(I.R.S. Employer Identification No.)

377 Plantation Street
Worcester, Massachusetts 01605
(Address including zip code of principal executive offices)

(781) 652-4500
(Registrant’s telephone number, including area code)

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

Title of each class
Common Stock, par value $0.0001 per share

Trading Symbol(s)
MBIO

Name of each exchange on which
registered
NASDAQ Capital 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   ⌧

Securities registered pursuant to section 12(g) of the Act: None.

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 the 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, 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
Emerging growth company

◻
☒
☐

Accelerated filer
Smaller reporting 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 in Rule 12b-2 of the Exchange Act). Yes    ☐ No   ⌧

The aggregate market value of the common stock held by non-affiliates of the registrant as of the last business day of the registrant’s most recently completed second fiscal quarter: $ 48.8
million.

Class of Common Stock
Class A Common Stock, $0.0001 par value
Common Stock, $0.0001 par value

DOCUMENTS INCORPORATED BY REFERENCE

Outstanding Shares as of March 27, 2023
845,385
109,398,635

Portions of the registrant’s Proxy Statement for its 2023 Annual Meeting of Stockholders are incorporated by reference into Part III hereof.

    
    
 
 
    
 
 
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MUSTANG BIO, INC.
ANNUAL REPORT ON FORM 10-K
TABLE OF CONTENTS

PART I
Item 1.
Item 1A.
Item 1B.
Item 2.
Item 3.
Item 4.

PART II
Item 5.
Item 6.
Item 7.
Item 7A.
Item 8.
Item 9.
Item 9A.
Item 9B.
Item 9C.

PART III
Item 10.
Item 11.
Item 12.
Item 13.
Item 14.

PART IV
Item 15.
Item 16.

Business
Risk Factors
Unresolved Staff Comments
Properties
Legal Proceedings
Mine Safety Disclosures

Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities
Reserved
Management’s Discussion and Analysis of Financial Condition and Results of Operations
Quantitative and Qualitative Disclosures About Market Risk
Financial Statements and Supplementary Data
Changes in and Disagreements with Accountants on Accounting and Financial Disclosure
Controls and Procedures
Other Information
Disclosure Regarding Foreign Jurisdiction that Prevents Inspections

Directors, Executive Officers and Corporate Governance
Executive Compensation
Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters
Certain Relationships and Related Transactions, and Director Independence
Principal Accountant Fees and Services

Exhibits and Financial Statement Schedules
Form 10-K Summary

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SPECIAL CAUTIONARY NOTICE REGARDING FORWARD-LOOKING STATEMENTS

Certain matters discussed in this annual report on Form 10-K (“Form 10-K”) may constitute forward-looking statements for purposes of the Securities Act of
1933, as amended (the “Securities Act”) and the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and involve known and unknown risks,
uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from the future results, performance or
achievements expressed or implied by such forward-looking statements. The words “anticipate,” “believe,” “estimate,” “may,” “expect” and similar expressions
are  generally  intended  to  identify  forward-looking  statements.  Our  actual  results  may  differ  materially  from  the  results  anticipated  in  these  forward-looking
statements due to a variety of factors, including, without limitation, those discussed under the captions “Risk Factors,” and elsewhere in this Form 10-K. All
written  or  oral  forward-looking  statements  attributable  to  us  are  expressly  qualified  in  their  entirety  by  these  cautionary  statements.  Such  forward-looking
statements include, but are not limited to, statements about our:

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expectations for increases or decreases in expenses;

expectations  for  the  clinical  and  pre-clinical  development,  manufacturing,  regulatory  approval,  and  commercialization  of  our  pharmaceutical  product
candidates or any other products we may acquire or in-license;

use of clinical research centers and other contractors;

expectations for incurring capital expenditures to expand our research and development and manufacturing capabilities;

expectations for generating revenue or becoming profitable on a sustained basis;

expectations or ability to enter into marketing and other partnership agreements;

expectations or ability to enter into product acquisition and in-licensing transactions;

expectations or ability to build our own commercial infrastructure to manufacture, market and sell our drug candidates;

expectations for the acceptance of our products by doctors, patients or payors;

ability to compete against other companies and research institutions;

ability to secure adequate protection for our intellectual property;

ability to attract and retain key personnel;

ability to obtain reimbursement for our products;

estimates  of  the  sufficiency  of  our  existing  cash  and  cash  equivalents  and  investments  to  finance  our  operating  requirements,  including  expectations
regarding the value and liquidity of our investments;

stock price and the volatility of the equity markets;

expected losses; and

expectations for future capital requirements.

The forward-looking statements contained in this Form 10-K reflect our views and assumptions as of the effective date of this Form 10-K. Except as required by
law, we assume no responsibility for updating any forward-looking statements.

We qualify all of our forward-looking statements by these cautionary statements.

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SUMMARY RISK FACTORS

Our business is subject to risks of which you should be aware before making an investment decision. The risks described below are a summary of the principal
risks associated with an investment in us and are not the only risks we face. You should carefully consider these risk factors, the risk factors described in Item
1A, and the other reports and documents that we have filed with the Securities and Exchange Commission (“SEC”).  

Risks Related to our Finances and Capital Requirements

● We have incurred significant losses since our inception and anticipate that we will incur continued losses for the foreseeable future.
●

There is substantial doubt regarding our ability to continue as a going concern. We will need to raise additional financing in upcoming periods, which
may  not  be  available  on  acceptable  terms  to  the  Company,  or  at  all.  Failure  to  obtain  necessary  capital  when  needed  may  force  us  to  delay,  limit  or
terminate  our  commercial  readiness  efforts,  activities  to  support  a  potential  commercial  launch  following  any  approval  of  our  product  candidates,  or
other operations.

● We have not generated any revenue from our development stage products, and we do not know when, or if, we will generate any revenue.
● Our short operating history makes it difficult to evaluate our business and prospects.
● Our success is contingent upon raising additional capital, which efforts may fail. Even if successful, our future capital raising activities may dilute our

current stockholders, restrict our operations, or cause us to relinquish proprietary rights.

Risks Pertaining to our Business Strategy, Structure and Organization

● Our future growth and success depend on our ability to successfully develop and commercialize our product candidates, which we have yet to do.
● Our growth and success depend on our acquiring or in-licensing products or product candidates and integrating such products into our business, and we

may have limited growth opportunities if we fail to do so.

● Our  future  success  is  highly  dependent  on  the  successful  development  of  our  chimeric  antigen  receptor  (“CAR”)  engineered  T  cell  (“CAR  T”)

technology and gene therapy product candidates.

Risks Inherent in Drug Development and Commercialization

Preclinical development is highly speculative and carries a high failure risk.  

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● We  may  not  receive  the  required  regulatory  approvals  for  any  of  our  product  candidates  on  our  projected  timelines,  if  at  all,  which  may  result  in

increased costs and delay our ability to generate revenue.

● We may not obtain the desired labeling claims or intended uses for product promotion, or favorable scheduling classifications, to successfully promote

●
●

our products.
If a product candidate demonstrates adverse side effects, we may need to abandon or limit the development of such product candidate.
Even  if  a  product  candidate  is  approved,  it  may  be  subject  to  various  post-marketing  requirements,  including  studies  or  clinical  trials,  and  increased
regulatory scrutiny.

● Our  competitors  may  develop  treatments  for  our  products’  target  indications,  which  could  limit  our  product  candidates’  commercial  opportunity  and

profitability.
If our products are not broadly accepted by the healthcare community, the revenues from any such product will likely be limited.

●
● Any successful products liability claim related to any of our current or future product candidates may cause us to incur substantial liability and limit the

commercialization of such products.

● Our  gene  therapy  product  candidates  are  based  on  a  novel  technology,  which  makes  it  difficult  to  predict  the  time  and  cost  of  product  candidate

development and subsequently obtaining regulatory approval.

Risks Related to Reliance on Third Parties

● We rely, and expect to continue to rely, on third parties to conduct our preclinical studies and clinical trials, and those third parties may not perform

satisfactorily, including failing to meet deadlines for the completion of such trials or complying with applicable regulatory requirements.

● We contract with third parties for the manufacture of our product candidates for preclinical and clinical testing and may also do so for commercialization,

if and when our product candidates are approved.

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● We rely on clinical data and results obtained by third parties, which may prove inaccurate or unreliable.
● We may need to license certain intellectual property from third parties, and such licenses may not be available or may not be available on commercially

reasonable terms.

Risks Relating to Legislation and Regulation Affecting the Biopharmaceutical and Other Industries

● We operate in a heavily regulated industry, and we cannot predict the impact that any future legislation or administrative or executive action may have on

our operations.

● We may be subject to anti-kickback, fraud and abuse, false claims, transparency, health information privacy and security and other healthcare laws and
regulations, which could expose us to criminal sanctions, civil penalties, contractual damages, reputational harm, administrative burdens and diminished
profits and future earnings.

● We are subject to numerous environmental, health and safety laws and regulations and could become subject to fines or penalties or incur costs that could

harm our business

Risks Pertaining to Intellectual Property and Potential Disputes with Licensors Thereof

●

If we are unable to obtain and maintain sufficient patent protection for our technology and products, our competitors could develop and commercialize
products similar or identical to ours and our ability to successfully commercialize our technology and products could be impaired.

● We depend on our licensors to maintain and enforce the intellectual property covering certain of our product candidates.
● We or our licensors may be subject to costly and time-consuming litigation for infringement of third-party intellectual property rights or to enforce our or

our licensors’ patents.

● Any dispute with our licensors may affect our ability to develop or commercialize our product candidates.

Risks Relating to Our Control by Fortress Biotech, Inc. (“Fortress”)

●

Fortress controls a voting majority of our common stock and has the right to receive significant share grants annually, which will result in dilution of our
other stockholders and could reduce the value of our common stock.

● We have entered into certain agreements with Fortress and may have received better terms from unaffiliated third parties.

Risks Related to Conflicts of Interest

● We share certain directors with Fortress, which could create conflicts of interest between us and Fortress.

General Risks

● We  have  received  notice  from  the  Nasdaq  Stock  Market  of  non-compliance  with  its  minimum  bid  price  rules;  our  common  stock  may  be  subject  to
delisting  from  The  Nasdaq  Capital  Market  if  we  are  unable  to  regain  compliance  which  may  decrease  the  market  liquidity  and  market  price  of  our
common stock.

PART I

Item 1.        Business

OVERVIEW

Mustang  Bio,  Inc.  (“Mustang,”  “we,”  “us”  or  the  “Company”)  is  a  clinical-stage  biopharmaceutical  company  focused  on  translating  today’s  medical
breakthroughs in cell and gene therapies into potential cures for hematologic cancers, solid tumors and rare genetic diseases. We aim to acquire rights to these
technologies by licensing or otherwise acquiring an ownership interest in the technologies, funding their research and development and eventually either out-
licensing or bringing the technologies to market.

Our pipeline is currently focused in three core areas: CAR T therapies for hematologic malignancies, CAR T therapies for solid tumors and gene therapies for
rare genetic disorders. For each therapy we have partnered with world class research institutions. For our CAR T therapies we have partnered with the City of
Hope  National  Medical  Center  (“COH”),  Fred  Hutchinson  Cancer  Center  (“Fred  Hutch”),  Nationwide  Children’s  Hospital  (“Nationwide”)  and  the  Mayo
Foundation for Medical Education and Research (“Mayo Clinic”). For our gene therapies,

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we have partnered with St. Jude Children’s Research Hospital (“St. Jude”) in the development of a first-in-class ex vivo lentiviral treatment of X-linked severe
combined  immunodeficiency  (“XSCID”)  and  with  Leiden  University  Medical  Centre  (“LUMC”)  for  RAG1  severe  combined  immunodeficiency  (“RAG1-
SCID”).

CAR T Therapies

Our  pipeline  of  CAR  T  therapies  is  being  developed  under  exclusive  licenses  from  several  world  class  research  institutions.  Our  strategy  is  to  license  these
technologies, support preclinical and clinical research activities by our partners and transfer the underlying technology to our cell processing facility located in
Worcester, Massachusetts, in order to conduct our own clinical trials.

We are developing CAR T therapies for hematologic malignancies in partnership with COH targeting CD123 (MB-102) and CS1 (MB-104) and with Fred Hutch
targeting CD20 (MB-106). Phase 1 clinical trials sponsored by COH for MB-102 and MB-104 and by Fred Hutch for MB-106 are underway. In July 2019 the
FDA approved our IND application to initiate a multi-center Phase 1/2 clinical trial of MB-102, and our clinical trial began enrollment in 2020 for the treatment
of patients with blastic plasmacytoid dendritic cell neoplasm (“BPDCN”). In May 2021, the FDA approved our IND application to initiate a multi-center Phase
1/2  clinical  trial  of  MB-106,  and  our  clinical  trial  began  enrollment  in  2022  for  treatment  of  patients  with  non-Hodgkin  lymphoma  (“NHL”)  and  chronic
lymphocytic leukemia (“CLL”). We plan to file an IND for a multicenter Phase 1/2 trial for MB-104 for the treatment of patients with multiple myeloma once
COH has established a safe and effective dose.

We are also developing CAR T therapies for solid tumors in partnership with COH targeting IL13Rα2 (MB-101), HER2 (MB-103) and PSCA (MB-105). In
addition, we have partnered with Nationwide for the C134 oncolytic virus (MB-108) in order to enhance the activity of MB-101 for the treatment of patients with
glioblastoma (“GBM”). Phase 1 clinical trials sponsored by COH for MB-101, MB-103 and MB-105 are underway. A Phase 1 clinical trial sponsored by the
University of Alabama at Birmingham (“UAB”) for MB-108 began during the third quarter of 2019, and we plan to file an IND for the combination of MB-101
and MB-108 – which is referred to as MB-109 – for the treatment of patients with relapsed or refractory GBM and anaplastic astrocytoma in 2023. In the third
quarter  of  2019,  we  announced  that  COH  had  started  enrolling  patients  on  a  Phase  1  clinical  trial  of  MB-101  in  combination  with  nivolumab  (trade  name:
Opdivo®)  and  ipilimumab  (trade  name:  Yervoy®)  in  patients  with  recurrent  malignant  glioma  (ClinicalTrials.gov  Identifier:  NCT04003649).  In  the  fourth
quarter  of  2020  we  announced  that  COH  had  initiated  a  Phase  1,  two-arm  clinical  trial  of  MB-101  in  patients  with  leptomeningeal  brain  tumors  (e.g.,
glioblastoma, ependymoma or medulloblastoma; ClinicalTrials.gov Identifier: NCT04003649).

Finally, the Company is collaborating with the Mayo Clinic to develop a novel technology that may be able to transform the administration of CAR T therapies
and potentially be used as an off-the-shelf therapy. Mustang plans to file an IND application for a multicenter Phase 1 clinical trial once a lead construct has
been identified.

Gene Therapies

In partnership with St. Jude, our XSCID gene therapy programs (MB-107 and MB-207) are being conducted under an exclusive license to develop a potentially
curative treatment for XSCID, a rare genetic immune system condition in which affected patients do not live beyond infancy without treatment. This first-in-
class ex vivo lentiviral gene therapy has been evaluated in two Phase 1/2 clinical trials involving two different autologous cell products: an ongoing multicenter
trial of the MB-107 product in newly diagnosed infants sponsored by St. Jude and a single-center trial of the MB-207 product in previously transplanted patients
sponsored  by  the  National  Institutes  of  Health  (“NIH”).  In  2022,  the  NIH  study  was  suspended  as  a  result  of  the  study  stopping  rules.  In  January  2021  we
received a safe to proceed “approval” from the U.S. Food and Drug Administration (“FDA”) for our MB-107 Investigational New Drug (“IND”) application
allowing us to initiate a pivotal non-randomized multicenter Phase 2 clinical trial of MB-107 in newly diagnosed infants with XSCID who are under the age of
two.  In  January  2022,  the  FDA  issued  a  clinical  hold,  pending  additional  Chemistry,  Manufacturing  and  Controls  (“CMC”)  data,  on  our  IND  application  to
conduct a pivotal non-randomized multicenter Phase 2 clinical trial of MB-207 in previously transplanted XSCID patients.

To  date,  we  have  not  received  approval  for  the  sale  of  our  product  candidates  in  any  market  and,  therefore,  have  not  generated  any  product  sales  from  our
product candidates. In addition, we have incurred substantial operating losses since our inception, and expect to continue to incur significant operating losses for
the foreseeable future and may never become profitable. As of December 31, 2022, we have an accumulated deficit of $329.4 million.

We are a majority-controlled subsidiary of Fortress.

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CORPORATE INFORMATION

Mustang Bio, Inc. was incorporated in Delaware on March 13, 2015. Our executive offices are located at 377 Plantation Street, Worcester, Massachusetts 01605.
Our telephone number is (781) 652-4500, and our email address is info@mustangbio.com.

Our website address is www.mustangbio.com. The information set forth on our website is not a part of this report. We will make available free of charge through
our website our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K, and any amendments to these reports, as soon as
reasonably practicable after we electronically file such material with, or furnish such material to, the SEC. We are not including the information on our website
as  a  part  of,  nor  incorporating  it  by  reference  into,  this  report.  The  SEC  maintains  a  website  that  contains  annual,  quarterly,  and  current  reports,  proxy  and
information statements, and other information that issuers (including us) file electronically with the SEC. The SEC’s website address is https://www.sec.gov/.

PRODUCTS UNDER DEVELOPMENT

CAR T Therapies for Hematologic Malignancies

MB-102 (CD123 CAR T Cell Program for BPDCN, AML and High-Risk MDS)

CD123  is  a  subunit  of  the  heterodimeric  interleukin-3-receptor  (“IL-3R”)  which  is  widely  expressed  on  human  hematologic  malignancies  including  blastic
plasmacytoid  dendritic  cell  neoplasm  (“BPDCN”)  and  acute  myeloid  leukemia  (“AML”).  In  addition,  CD123  can  be  found  on  the  surface  of  B  cell  acute
lymphoblastic leukemia (“B-ALL”), hairy cell leukemia, myelodysplastic syndrome (“MDS”), chronic myeloid leukemia (“CML”) and Hodgkin lymphoma.

Of  these  malignancies,  we  are  currently  investigating  CD123  as  a  target  for  adoptive  cellular  immunotherapy  in  BPDCN,  since  high  CD123  expression  is
associated with enhanced cell proliferation, increased resistance of these cells to apoptosis, and poor clinical prognosis. Depending on the early results in this
patient population, we may broaden the inclusion criteria to include AML and high-risk MDS (“HR-MDS”). CD123 is overexpressed in the vast majority of
cases of AML and HR-MDS and in essentially all cases of BPDCN.

AML is a cancer of the myeloid line of blood cells characterized by rapid growth of abnormal white blood cells that accumulate in the bone marrow. AML is the
most common form of acute leukemia. Although AML is a relatively rare disease, there are approximately 20,000 new cases per year in the U.S. and 10,000
deaths per year, accounting for approximately 1.8% of cancer deaths in the U.S. [Source: The Surveillance, Epidemiology, and End Results (“SEER”) Program of
the National Cancer Institute]. AML standard of care involves chemotherapy to induce remission followed by additional chemotherapy or a hematopoietic stem
cell  transplant. Allogeneic  stem  cell  transplantation  (“allo-SCT”)  is  the  preferred  treatment  for AML  following  a  second  remission.  It  can  lead  to  a  5-year
disease-free  survival  in  26%  of  patients.  Unfortunately,  however,  currently  only  about  half  of  relapsed  patients  are  able  to  achieve  a  second  remission  with
traditional chemotherapy agents. Patients who do not achieve a second remission are much less likely to benefit from transplantation and face a dismal outcome.

MDS is a heterogeneous group of malignant hematopoietic stem cell disorders characterized by dysplastic and ineffective blood cell production and a variable
risk of transformation to acute leukemia. Patients with MDS have varying reductions in the production of red blood cells, platelets, and mature granulocytes that
may also exhibit functional defects; these abnormalities often result in anemia, bleeding, and increased risk of infection. The precise incidence of de novo MDS
is  not  known;  conservative  estimates  from  cancer  databases  suggest  that  there  are  approximately  10,000  cases  diagnosed  annually  in  the  U.S.  The  actual
incidence of MDS is likely higher than that predicted by cancer databases, since the nonspecific symptoms may evade detection in early stages of the disease
and suspected cases may not undergo definitive testing (i.e., bone marrow biopsy) due to comorbidities. Investigations that have analyzed reimbursement claims
have estimated the incidence in the U.S. to be 30,000 to 40,000 new cases per year. MDS occurs most commonly in older adults, with a median age at diagnosis
in most series of ≥65 years and a male predominance.

MDS and AML lie along a disease continuum, with distinction between the two largely made based upon the percentage of myeloblasts, which are immature
cells with large nuclei, nucleoli, and a scant rim of dark blue cytoplasm, suggesting an underlying malignant hematologic disorder. In the current World Health
Organization (“WHO”) classification system, blast forms must account for less than 20% of the total cells of the bone marrow aspirate and peripheral blood to
meet the criteria for MDS.

MDS prognosis is often assessed using the revised International Prognostic Scoring System (“IPSS-R”), which takes into account cytogenetics, percentage of
bone marrow blasts, and the degree of anemia, thrombocytopenia, and neutropenia. This System categorizes patients into very low, low, intermediate, high, and
very high risk MDS. High risk and very high risk MDS are characterized by more

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unfavorable  cytogenetics,  bone  marrow  blast  percentages  greater  than  5%  but  under  the  20%  threshold  for  AML,  and  worse  cytopenias  (anemia,
thrombocytopenia,  and  neutropenia)  –  all  of  which  cumulatively  generate  an  IPSS-R  score  of  >4.5  to  6  for  high  risk  MDS  and  >6  for  very  high  risk  MDS.
Furthermore, they are generally progressive in nature and can easily progress to AML. Treatment is stratified according to medical fitness in a manner similar to
that  for  older  patients  with AML.  Patients  who  are  medically  fit  or  of  intermediate  fitness  are  generally  evaluated  soon  after  diagnosis  to  determine  their
suitability for allo-SCT. For patients who are not candidates for intensive treatment, care is focused on relieving symptoms and improving the quality of life and
might involve lower intensity treatment, for example, with azacitidine, decitabine, or targeted therapy. Patients with recurrent or refractory higher risk MDS may
be encouraged to participate in clinical trials. Outside of a clinical trial, the management of patients with recurrent or refractory MDS is largely dependent on the
patient’s prior therapy.

BPDCN is categorized by the WHO under AML. Most often, BPDCN presents with features of both lymphoma and leukemia. There is little data about BPDCN
and the only approved drug for this disease is tagraxofusp-erzs, which is indicated for the treatment of adult and pediatric patients with both treatment-naïve and
previously-treated  BPDCN.  The  average  age  at  diagnosis  is  60  to  70  years.  BPDCN  is  very  often  misdiagnosed  and  under-reported.  The  skin  is  the  most
frequently involved site of disease (80 percent of cases). However, BPDCN usually progresses with bone marrow involvement and a decrease in red blood cell,
white blood cell and platelet counts. The lymph nodes and spleen may also be involved. Common misdiagnoses for BPCDN include non-Hodgkin lymphoma
(“NHL”), AML, leukemia cutis [a nonspecific term used for cutaneous (skin) manifestation of any type of leukemia], melanoma (a type of skin cancer), and
lupus  erythematosus  (chronic  inflammatory  disease  that  occurs  when  the  body’s  immune  system  attacks  its  own  tissues  and  organs).  There  are  no  data  or
randomized  clinical  trials  that  can  define  the  best  first  treatment  for  patients  with  BPDCN.  In  addition  to  the  emerging  use  of  tagraxofusp-erzs,  which  was
approved  by  the  FDA  in  December  2018,  treatment  sometimes  includes  therapies  that  are  used  for AML, ALL,  or  lymphoma.  The  time  for  which  a  patient
responds to these treatments is usually short. After a relapse, second remissions with conventional chemotherapy are difficult to achieve. allo-SCT, especially if
offered  in  first  remission,  may  result  in  longer  remissions.  The  current  recommendation  is  for  BPDCN  patients  to  be  evaluated  for  an  allo-SCT  as  soon  as
possible and to begin searching for a donor.

The use of CAR T immunotherapy in relapsed BPDCN, AML, and HR-MDS patients may offer the potential to achieve a complete or longer lasting remission.
COH investigators have developed CD123-targeted CAR T cells designed to be activated, to proliferate, and to kill CD123-expressing tumor cells [Mardiros A
et al. Blood.  2013;122(18):3138-3148].  The  therapy  is  designed  to  recognize  and  eliminate  malignant  cells,  leading  to  remission  in  patients  with  relapsed  or
refractory  BPDCN,  AML,  and  HR-MDS,  and  could  serve  as  a  bridge  to  potentially  curative  allogeneic  stem  cell  transplant.  The  manufacturing  process
genetically  modifies  T  cells  isolated  from  peripheral  blood  mononuclear  cells  in  order  to  express  a  CD123-specific,  hinge-optimized,  CD28  co-stimulatory
domain-expressing CAR.

In October 2020, we announced the dosing of the first patient in a multicenter Phase 1/2 clinical trial of MB-102 in patients with relapsed or refractory BPDCN
(Clinicaltrials.gov Identifier: NCT04109482). This is also the first clinical trial under a Mustang IND in which a patient was dosed with cells processed in our
manufacturing facility. In December 2022, we announced that the safety review team (“SRT”), after thoroughly reviewing the safety data from Dose Level 1
(100 x 106 CAR T cells), unanimously recommended dose escalation to Dose Level 2 (300 x 106 CAR T cells). We anticipate initiation of Dose Level 2 cohort
in 2023.

MB-104 (CS1 CAR T for Multiple Myeloma and Light Chain Amyloidosis)

CS1 (also known as CD319, CRACC and SLAMF7) was identified as a natural killer (“NK”) cell receptor regulating immune functions. It is also expressed on
B  cells,  T  cells,  dendritic  cells,  NK-T  cells,  and  monocytes.  CS1  is  overexpressed  in  multiple  myeloma  (“MM”)  and  light  chain  amyloidosis  (“AL”),  which
makes  it  a  good  target  for  immunotherapy. A  humanized  anti-CS1  antibody,  elotuzumab  (Empliciti™),  has  shown  promising  results  in  clinical  studies  and
was initially approved by the FDA in 2015 in combination with lenalidomide and dexamethasone for the treatment of patients with multiple myeloma who have
received one to three prior therapies.  Despite  great  advances  in  treatment,  MM  remains  an  incurable  malignancy  of  plasma  cells. AL  is  a  protein  deposition
disorder that is a result of a plasma cell dysplasia, similar to MM. Immunotherapy is an attractive approach for AL because of the low burden of disease. Our
academic partners at COH have developed a novel second generation CS1-specific CAR T cell therapy. In preclinical studies, they have demonstrated efficacy
of these CAR T cells, both in vitro and in vivo, within the context of clinically relevant models of MM and AL. COH is evaluating the safety of this CS1-specific
CAR T cell therapy in a Phase 1 trial that commenced in the first half of 2019 (ClinicalTrials.gov Identifier: NCT03710421). Once COH has established a safe
and effective dose for MB-104 in this trial, we expect to file an IND for a multicenter Phase 1/2 trial for the treatment of patients with MM.

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MB-106 (CD20 CAR T for B cell non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL))

CD20 is a promising target for immunotherapy of B-cell malignancies. CD20 is a B-cell lineage-specific phosphoprotein that is expressed in high, homogeneous
density on the surface of more than 95% of B-cell NHL and CLL. CD20 is stable on the cell surface with minimal shedding, internalization, or modulation upon
antibody binding and is present at only nanomolar levels as a soluble antigen. It is well established as an effective immunotherapy target, with extensive studies
demonstrating improved tumor responses and survival of B-NHL patients treated with rituximab and other anti-CD20 antibodies. Importantly, CD20 continues
to be expressed on the lymphoma cells of most patients with relapsed B-NHL despite repetitive rituximab treatments, and loss of CD20 expression is not a major
contributor to treatment resistance. Thus, there is strong rationale for testing CD20 CAR T cells as an immunotherapy for NHL.

More than 80,000 new cases of NHL are diagnosed each year in the United States, and over 20,000 patients die of this group of diseases annually. Most forms
of  NHL  including  follicular  lymphoma,  mantle  cell  lymphoma,  marginal  zone  lymphoma,  lymphoplasmacytic  lymphoma,  and  small  lymphocytic  lymphoma
(“SLL”), which account collectively for ~45% of all cases of NHL, are incurable with available therapies, except for allo-SCT. However, many NHL patients are
not  suitable  candidates  for  allo-SCT,  and  this  treatment  is  also  limited  by  significant  rates  of  morbidity  and  mortality  due  to  graft-versus-host  disease.
Aggressive B-cell lymphomas such as diffuse large B-cell lymphoma account for an additional 30-35% of NHL. The majority of patients with aggressive B-
NHL are successfully treated with combination chemotherapy, but a significant proportion relapse or have refractory disease, and the outcome of these patients
is poor. Innovative new treatments are therefore urgently needed.

Chronic  lymphocytic  leukemia/small  lymphocytic  lymphoma  (CLL/SLL)  is  a  mature  B  cell  neoplasm  characterized  by  a  progressive  accumulation  of
monoclonal B lymphocytes. CLL is considered to be identical (i.e., one disease with different manifestations) to the NHL SLL. The malignant cells seen in CLL
and SLL have identical pathologic and immunophenotypic features. The term CLL is used when the disease manifests primarily in the blood, whereas the term
SLL is used when involvement is primarily nodal.

CLL is the most common leukemia in adults in Western countries, accounting for approximately 25 to 35 percent of all leukemias in the United States. It is
estimated that 18,740 new cases of CLL will be diagnosed in the United States in 2023. CLL is considered to be mainly a disease of older adults, with a median
age  at  diagnosis  of  approximately  70  years;  however,  it  is  not  unusual  to  make  this  diagnosis  in  younger  individuals  (e.g.,  from  30  to  39  years  of  age).  The
incidence  increases  rapidly  with  increasing  age.  The  natural  history  of  CLL  is  extremely  variable,  with  survival  times  from  initial  diagnosis  that  range  from
approximately 2 to 20 years, and a median survival of approximately 10 years.

Most patients will have a complete or partial response to initial therapy. However, conventional therapy for CLL is not curative and most patients experience
relapse. In addition, many patients will require a change in therapy due to intolerance. Since patients with CLL are generally elderly with a median age older
than 70 years, and due to the relatively benign course of the disease in the majority of patients, only selected patients are candidates for intensive treatments such
as allo-SCT. Innovative new treatments with a favorable safety profile are therefore urgently needed for patients with relapsed and refractory disease.

Under their IND, Fred Hutch is currently conducting a Phase 1/2 clinical study to evaluate the anti-tumor activity and safety of administering CD20-directed
third-generation CAR T cells incorporating both 4-1BB and CD28 co-stimulatory signaling domains  (MB-106) to patients with relapsed or refractory B-cell
NHL  or  CLL  (ClinicalTrials.gov  Identifier:  NCT03277729).  Secondary  endpoints  of  this  study  include  safety  and  toxicity,  preliminary  antitumor  activity  as
measured  by  overall  response  rate  and  complete  remission  rate,  progression-free  survival,  and  overall  survival.  The  study  is  also  assessing  CAR  T  cell
persistence  and  the  potential  immunogenicity  of  the  cells.  Finally,  the  study  was  designed  so  that  Mustang  together  with  Fred  Hutch  could  determine  a
recommended Phase 2 dose. Fred Hutch intends to enroll approximately 50 subjects in the study, which is being led by Principal Investigator Mazyar Shadman,
M.D., M.P.H., Assistant Member of Fred Hutch’s Clinical Research Division.

The Fred Hutch IND was amended in 2019 to incorporate an optimized manufacturing process that had been developed in collaboration with Mustang.

In May 2021, we announced that the FDA had approved our IND application  allowing for initiation of a multi-center Phase 1/2 clinical study  of MB-106 in
patients with relapsed or refractory B cell NHL or CLL (Clinicaltrials.gov Identifier: NCT05360238).

In November 2021, Mustang was awarded a grant of approximately $2 million from NCI of the National Institutes of Health. This two-year award will partially
fund the Mustang-sponsored multicenter trial to assess the safety, tolerability and efficacy of MB-106.

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CAR T Therapies for Solid Tumors

MB-103 (HER2 CAR T for GBM & Metastatic Breast Cancer to Brain)

HER2/neu  (“HER2”)  is  a  growth-promoting  protein  on  the  outside  of  all  breast  cells.  Breast  cancer  cells  with  higher-than-normal  levels  of  HER2  are  called
HER2-positive (“HER2+”). These cancers tend to grow and spread faster than other breast cancers. Breast cancer is the most commonly diagnosed cancer in
women, with over 42,000 women in the United States expected to die from advanced metastatic disease in 2023. Approximately 20% to 25% of breast cancers
overexpress HER2, which is an established therapeutic target of both monoclonal antibodies (mAbs) and receptor tyrosine kinase inhibitors. With the advent of
effective mAbs directed against HER2, the median overall survival of patients with metastatic HER2+ breast cancer has improved. However, management of
metastatic disease in the brain and/or CNS – observed in up to 50% of HER2+ breast cancer patients – continues to be a clinical challenge in large part due to the
inability of mAbs to sufficiently cross the blood-brain barrier. Although small-molecule inhibitors of HER2 exist and have been clinically approved, their single-
agent  efficacy  in  the  context  of  metastatic  disease  to  the  brain  has  been  limited.  While  HER2-targeted  therapy  in  combination  with  conventional  agents  has
shown some promise for the treatment of patients with metastatic breast cancer, control of brain metastases remains a significant unmet clinical need, as most
patients  survive  less  than  two  years  following  CNS  involvement.  Recent  advances  in  cellular  immunotherapy  approaches  have  underscored  the  potential  for
potent antitumor immune responses and clinical benefit against solid cancers, and these approaches may be effective in the treatment of HER2+ cancers – in
particular breast cancer – that have metastasized to the brain. Likewise, HER2 has been suggested as a suitable target for GBM, wherein elevated HER2 protein
levels have been correlated with impaired survival.

CAR  T  cell  immunotherapy  is  being  actively  investigated  for  the  treatment  of  solid  tumors,  including  HER2+  cancers.  Our  academic  partners  at  COH  have
developed a second-generation HER2-specific CAR T cell therapy for the treatment of brain and/or leptomeningeal metastases from HER2+ cancers, as well as
for  the  treatment  of  refractory/relapsed  HER2+  GBM.  COH’s  preclinical  data  demonstrate  effective  targeting  of  breast  cancer  brain  metastases  with
intraventricular  delivery  of  CAR  T  cells  expressing  HER2-CARs  that  contain  the  4-1BB  costimulatory  domain.  COH  is  evaluating  the  safety  of  this  HER2-
specific CAR T cell therapy in two ongoing Phase 1 clinical trials that commenced in the fourth quarter of 2018 (ClinicalTrials.gov Identifier: NCT03389230 for
HER2+ GBM; ClinicalTrials.gov Identifier: NCT03696030 for HER2+ brain metastases).

MB-105 (PSCA CAR T for Prostate & Pancreatic Cancers)

PSCA is a glycosylphosphatidylinositol-anchored cell membrane glycoprotein. In addition to being highly expressed in the prostate it is also expressed in the
bladder, placenta, colon, kidney, and stomach. This gene is upregulated in a large proportion of prostate cancers and is also detected in cancers of the bladder and
pancreas. The gene includes a polymorphism that results in an upstream start codon in some individuals; this polymorphism is thought to be associated with a
risk for certain gastric and bladder cancers. Prostate cancer may be amenable to T cell-based immunotherapy since several tumor antigens, including prostate
stem-cell antigen (“PSCA”), are widely overexpressed in metastatic disease. Our academic partners at COH have developed a second-generation PSCA-specific
CAR T cell therapy that has demonstrated robust in vitro and in vivo anti-tumor activity in patient-derived, clinically relevant, bone-metastatic prostate cancer
xenograft models. COH is evaluating the safety of this PSCA-specific CAR T cell therapy in an ongoing Phase 1 trial treating patients with PSCA+ metastatic
castration-resistant prostate cancer (ClinicalTrials.gov Identifier: NCT03873805).

In October 2020,we announced initial data from this Phase 1 clinical trial in patients with PSCA-positive castration-resistance prostate cancer (“CRPC”). In the
presentation at the 2020 Annual Prostate Cancer Foundation Scientific Retreat, the COH principal investigator reported results from a highly refractory patient
treated  with  MB-105  who  experienced  a  94  percent  reduction  in  prostate-specific  antigen  (“PSA”),  a  nearly  complete  reduction  of  measurable  soft  tissue
metastasis by computerized tomography, and improvement in bone metastases by magnetic resonance imaging.

MB-109: Combination MB-101(IL13Rα2 CAR T Cell Program for Glioblastoma) and MB-108 (HSV-1 oncolytic virus C134) as a Potential Treatment for
IL13Rα2+ Relapsed or Refractory Glioblastoma (GBM) and Anaplastic Astrocytoma (AA).

An attractive novel approach to control glioblastoma is adoptive cellular immunotherapy utilizing CAR T cells. CAR T cells can be engineered to recognize very
specific antigenically distinct tumor populations and to migrate through the brain parenchyma to kill malignant cells. In addition, oncolytic viruses (“OVs”) have
been developed to effectively infect and kill cancer cells in the tumor, as well as modify the microenvironment to increase tumor immunogenicity and immune
cell  trafficking  within  the  tumor.  Due  to  these  properties,  OVs  have  been  studied  in  combination  with  other  treatments  to  enhance  the  effectiveness  of
immunotherapies.

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Preliminary  anti-tumor  activity  has  been  observed  in  clinical  studies  administering  the  OV  (MB-108)  and  CAR  T  cell  therapy  (MB-101)  as  single  agents;
however,  the  combination  has  not  yet  been  explored.  To  determine  if  the  combination  of  both  therapies  will  result  in  a  synergistic  effect,  investigators  from
COH developed preclinical studies in orthotopic GBM models in nude mice.  Dr. Christine Brown from City of Hope presented these preclinical studies at the
American Association for Cancer Research 2022 annual meeting.  It was observed that co-treatment with C134 OV and IL13Rα2-directed CAR-T cells gave no
adverse reaction and, more notably, that pre-treatment with C134 re-shaped the tumor microenvironment by increasing immune cell infiltrates and enhanced the
efficacy of sub-therapeutic doses of CAR-T cell therapy delivered either intraventricularly or intratumorally. These preclinical studies aimed to provide a deeper
understanding of this combination approach to support the potential benefit of a combination study that will evaluate C134 OV (MB-108) and IL13Rα2-directed
CAR-T cells (MB-101).

We received Pre-IND Written Responses from the FDA in May 2022, and we expect to file an IND for the combination trial of C134 oncolytic virus (MB-108)
and IL13Rα2-directed CAR- T cells (MB-101) in 2023.  In the planned Phase 1 clinical study, we intend to evaluate the combination of CAR-T cells (MB-101)
and the C134 oncolytic virus (MB-108) in patients with IL13Rα2+ high-grade gliomas.  The proposed design of this study will  investigate increasing doses of
intratumorally administered MB-108 followed by dual intratumoral (ICT) and intraventricular (ICV) administration of MB-101.

MB-101 (IL13Rα2 CAR T Cell Program for Glioblastoma)

GBM is the most common brain and central nervous system (“CNS”) cancer, accounting for 49.1% of malignant primary brain and CNS tumors, 54% of all
gliomas, and 16% of all primary brain and CNS tumors. More than 13,000 new glioblastoma cases were predicted in the U.S. for 2022. Malignant brain tumors
are the second leading cause of cancer-related deaths in adolescents and young adults aged 15-39 and the most common cancer occurring among 15-19-year-
olds in the U.S. While GBM is a rare disease [2-3 cases per 100,000 persons per year in the U.S. and European Union (“EU”)], it is quite lethal, with five-year
survival rates historically under 10%. Standard of care therapy consists of maximal surgical resection, radiation, and chemotherapy with temozolomide, which,
while rarely curative, is shown to extend median overall survival from 4.5 to 15 months. GBM remains difficult to treat due to the inherent resistance of the
tumor to conventional therapies.

Immunotherapy  approaches  targeting  brain  tumors  offer  promise  over  conventional  treatments.  IL13Rα2  is  an  attractive  target  for  CAR  T  therapy,  as  it  has
limited expression in normal tissue but is overexpressed on the surface of greater than 50% of GBM tumors. CAR-T cells are designed to express membrane-
tethered IL-13 receptor ligand (“IL-13”) mutated at a single site (glutamic acid at position 13 to a tyrosine; E13Y) with high affinity for IL13Rα2 and reduced
binding to IL13Rα1 in order to reduce healthy tissue targeting (Kahlon KS et al. Cancer Research. 2004;64:9160-9166).

We are developing an optimized CAR-T product incorporating enhancements in CAR-T design and T cell engineering to improve antitumor potency and T cell
persistence. These include a second-generation hinge-optimized CAR containing mutations in the IgG4 linker to reduce off-target Fc interactions (Jonnalagadda
M et al. Molecular Therapy. 2015;23(4):757-768.), a 4-1BB (CD137) co-stimulatory signaling domain for improved survival and maintenance of CAR T cells,
and the extracellular domain of CD19 as a selection/tracking marker. In order to further improve persistence, either central memory T-cells (T CM ) or enriched
CD62L+ naïve and memory T cells (TN/MEM) are isolated and enriched. Our manufacturing process limits ex vivo expansion, which is designed to reduce T cell
exhaustion and maintain a TCM or TN/MEM phenotype. Based on experiments with CAR-Ts in mouse xenograft models of GBM, these CAR-modified TCM and
TN/MEM cells have been shown to be more potent and persistent than earlier generations of CAR-T cells.

Our academic partners at COH have completed a Phase 1 study to assess the feasibility and safety of using TCM or TN/MEM  enriched  IL13Rα2-specific  CAR-
engineered  T  cells  for  clinical  study  participants  with  recurrent/refractory  malignant  glioma  (ClinicalTrials.gov  Identifier:  NCT02208362). As  of  May  2022
COH had enrolled and treated 65 patients.  Preliminary data for patients enrolled in Arm 2 of the protocol (the “Intracavitary Arm”) were presented at the annual
meeting  of  the American Association  for  Cancer  Research  in April  2018.  The  data  indicated  that  the  CAR-T  cells  were  well  tolerated,  and  no  dose-limiting
toxicities had been observed. In 2016 COH reported that a patient had achieved a complete response to treatment based on the imaging and clinical features set
forth by the Response Assessment in Neuro-Oncology Criteria (“RANO”). This result was published as a case report in the  New England Journal of Medicine
(Brown CE et al. NEJM. 2016;375:2561-9). As described in the paper, this patient diagnosed with recurrent multifocal glioblastoma received multiple infusions
of IL13Rα2-specific CAR-T cells over 220 days through two intracranial delivery routes – infusions into the resected tumor cavity followed by infusions into the
ventricular system. Intracranial infusions of IL13Rα2-targeted CAR-T cells were not associated with any toxic effects of grade 3 or higher. After CAR-T cell
treatment,  regression  of  all  intracranial  and  spinal  tumors  was  observed,  along  with  corresponding  increases  in  levels  of  cytokines  and  immune  cells  in  the
cerebrospinal  fluid.  This  clinical  response  was  sustained  for  7.5  months  after  the  initiation  of  CAR  T-cell  therapy;  however,  the  patient’s  disease  eventually
recurred at four new locations that were distinct and non-adjacent to the original tumors, and biopsy of one of these lesions showed decreased expression of
IL13Rα2. With

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enrollment in this Phase 1 study completed, COH has established the recommended Phase 2 dose, schedule and route of administration, as well as the optimal T
cell selection.

Results from this COH study have laid the foundation for 3 new MB-101 studies:

1. MB-101  with  or  without  nivolumab  and  ipilimumab  in  treating  patients  with  recurrent  or  refractory  glioblastoma  (currently  enrolling  patients;

ClinicalTrials.gov Identifier: NCT04003649) sponsored by COH;

2. MB-101  in  treating  patients  with  recurrent  or  refractory  glioblastoma  with  a  substantial  component  of  leptomeningeal  disease  (currently  enrolling

patients; ClinicalTrials.gov Identifier: NCT04661384) sponsored by COH;

3. MB101 in combination with the C134 oncolytic virus (MB108) in treating patients with recurrent or refractory glioblastoma or anaplastic astrocytoma
(IND filing expected in 2023). This combination therapy, to be administered in a phase 1 two-center trial under Mustang IND, will be referred to as MB-
109.

Technology to Convert GBM from an Immunologically Cold Tumor to an Immunologically Hot Tumor

MB-108 (HSV-1 oncolytic virus C134)

MB-108 is a next-generation oncolytic herpes simplex virus (“oHSV”) that is conditionally replication competent; that is, it can replicate in tumor cells, but not
in normal cells, thus killing the tumor cells directly through this process. Replication of C134 in the tumor itself not only kills the infected tumor cells but causes
the tumor cell to act as a factory to produce new virus. These virus particles are released as the tumor cell dies and can then proceed to infect other tumor cells in
the vicinity and continue the process of tumor kill. In addition to this direct oncolytic activity, the virus promotes an immune response against surviving tumor
cells,  which  increases  the  antitumor  effect  of  the  therapy.  The  virus  expresses  a  gene  from  another  virus  from  the  same  overall  virus  family,  human
cytomegalovirus,  which  allows  it  to  replicate  better  in  the  tumor  cells  than  its  first-generation  predecessors.  However,  the  virus  has  also  been  genetically
engineered to minimize the production of any toxic effects for the patient receiving the therapy.

To improve this virus over its first-generation predecessors, modifications have focused on improving viral replication and spread within the tumor bed and on
enhancing  bystander  damage  to  uninfected  tumor  cells.  These  effects  cumulatively  should  result  in  converting  an  immunologically  cold  tumor  to  an
immunologically  hot  tumor,  which  Mustang  anticipates  will  increase  the  efficacy  of  its  IL13Rα2-directed  CAR  T  for  the  treatment  of  GBM  and  anaplastic
astrocytoma.

UAB is the clinical trial site for the Phase 1 trial of MB-108, and the site has initiated a Phase 1 trial that began enrolling patients in 2019 (ClinicalTrials.gov
Identifier:  NCT03657576).  The  primary  objective  of  this  study  is  to  determine  the  safety  and  tolerability  of  stereotactic  intracerebral  injections  of  escalating
doses of MB-108 and to determine the maximally tolerated dose (“MTD”) of the oncolytic virus. Secondary objectives are to obtain preliminary information
about the potential benefit of MB-108 in the treatment of patients with recurrent malignant gliomas, including relevant data on markers of efficacy, including
time to tumor progression and patient survival. This trial has been on clinical hold since September 2022 due to toxicity, and UAB expects FDA clearance in
2023 in order to resume enrolling patients at a lower dose level.

In Vivo CAR T Platform Technology

Mustang  is  collaborating  with  the  Mayo  Clinic  to  develop  a  novel  technology  that  may  be  able  to  transform  the  administration  of  CAR  T  therapies  and
potentially be used as an off-the-shelf therapy. The technology, developed by Larry R. Pease, Ph.D., principal investigator and former director of the Center for
Immunology and Immune Therapies at Mayo Clinic, is a new platform to administer CAR T therapy using a two-step approach. First, a peptide is administered
to the patient to drive the proliferation of the patient’s resident T cells. This is followed by the administration of a viral CAR construct directly into the lymph
nodes of the patient. In turn, the viral construct infects the activated T cells and effectively forms CAR T cells in vivo in the patient. Successful implementation
may lead to an off-the-shelf product with no need to isolate and expand patient T cells ex vivo.

Preclinical proof-of-concept has been established, and the ongoing development of this technology will take place at Mayo Clinic.  Mustang plans to file an IND
application for a multicenter Phase 1 clinical trial once a lead construct has been identified.

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Gene Therapies for Rare Genetic Disorders

MB-107 and MB-207 (Ex vivo Lentiviral Therapy for X-linked Severe Combined Immunodeficiency (XSCID))

XSCID  is  a  rare  genetic  immune  system  condition  that  occurs  almost  exclusively  in  males,  in  which  affected  patients  do  not  live  beyond  infancy  without
treatment. Mustang Bio’s first-in-class ex vivo lentiviral gene therapy for XSCID has been administered as two distinct cellular products using the same lentiviral
vector in two phase 1/2 clinical trials: (1) an ongoing multicenter trial of MB-107 in newly diagnosed patients being led by St. Jude and including also UCSF
Benioff Children’s Hospital San Francisco (“UCSF”) and Seattle Children’s Hospital (“Seattle Children’s”) (ClinicalTrials.gov Identifier: NCT01512888) and
(2) a single center trial of MB-207 at the NIH in patients who have previously undergone hematopoietic stem cell transplantation (ClinicalTrials.gov Identifier:
NCT01306019).

MB-207 (previously transplanted patients):

The  last  peer-reviewed  presentation  by  the  NIH  Principal  Investigator,  Dr.  Harry  Malech,  occurred  at  the  61st Annual  Meeting  of  the American  Society  of
Hematology (“ASH”) in December 2019, at which time 24 patients had been treated in total. Eleven patients under the age of two years had been treated at St.
Jude and UCSF and thirteen patients 3 to 34 years of age had been treated at the NIH.

The existing data from these 24 patients were encouraging. In the initial stage of accrual to the Phase 1/2 NIH trial, eight patients (referred to as Cohort A) were
followed for 3 to 7 years. Among Cohort A, seven patients aged 3 to 23 years increased host T cells chimerism from 0-2% to 28-93% and had normal T cell
proliferation response. These seven patients also normalized their IgM levels, and four of these patients were able to discontinue immunoglobulin replacement
therapy. In addition, gradual clinical benefit was observed in the clearance of chronic norovirus and associated abdominal complaints, malabsorption, and growth
retardation, with six of seven affected patients being cured of their disease. Five of six patients resolved their protein-losing enteropathy.

While the Cohort A results were impressive, the relatively inefficient transduction of hematopoietic stem/progenitor cells (“HSPCs”) required large quantities of
vector. This resulted in relatively low vector copy number in myeloid cells in some patients, with delayed immune cell recovery and persistent clinical disease,
especially  in  the  last  patient  treated  (patient  8).  To  address  this,  NIH  developed  a  refined  enhanced  transduction  (“ET”)  procedure  and  incorporated  two
transduction enhancers: LentiBOOST™ 1mg/mL and dimethyl prostaglandin 2 (dmPGE2; 1µM) into the manufacturing process from MB-207.

In addition to the Cohort A results, the NIH presentation at the 2019 ASH Annual Meeting included data from six ET patients (referred to as Cohort B) treated
from February to June 2019, including re-treatment of patient 8. Prior to undergoing gene therapy, the patients, who were aged 12 to 36 years, had significant
problems  with  donor  T  cell  infiltration  of  liver,  bone  marrow  and  kidneys  and  had  nearly  absent  B  and  NK  cells.  The  ET  procedure  achieved  much  greater
transduction efficiencies than were observed in Cohort A, with greater than 10-fold less vector, and resulted in faster immune reconstitution and more significant
clinical benefit by 3 months. As noted by the investigators, longer follow-up will be required to know if the increased vector marking using the ET regimen will
prove to be stable and safe long term.

In all NIH patients, the low-dose, nonmyeloablative busulfan pretreatment conditioning was well tolerated, and of a low enough intensity to avoid the need for
transfusions of red blood cells or platelets. No evidence of malignant transformation was observed.

In a press release dated February 2, 2021, we further disclosed that, of the 6 Cohort A patients who were alive at the time of the 2019 NIH data readout and who
did  not  undergo  repeat  therapy,  3  patients  were  able  to  discontinue  chronic  intravenous  immunoglobulin  (IVIG)  and  experienced  sustained  restoration  of
humoral responses to immunization. The remaining 3 patients had reduced IVIG requirements. All chronic norovirus infections were resolved, and the quality of
life of all patients had improved significantly. The original 6 patients in Cohort B also continued to do well, with the longest follow-up being 22 months. Two
additional patients were successfully treated with transduction enhancers, for a total of 8 patients in Cohort B. As was the case in Cohort A, no serious adverse
events  related  to  treatment  were  reported  other  than  hematologic  related  to  low-dose  busulfan  conditioning,  and  there  was  no  evidence  of  malignant
transformation.

As a result of the study stopping rules, the NIH study was suspended in 2022 due to the presence of clonal expansion in the myeloid lineage in 10% of the treated
patients, although to date there have been no observations of insertional mutagenesis or malignancies. All patients continue to be followed and remain clinically
stable with no significant hematological anomalies. Upon review of these data, the FDA agree that the risk-benefit ration of both MB-107 and MB-207 remains
favorable to support moving forward with the Mustang-sponsored multicenter clinical trials once Mustang has appropriately addressed other items flagged by the
Agency.  

The IND for MB-207 was submitted to the FDA in December 2021.  In January 2022, the FDA issued a clinical hold, pending additional CMC data. In order to
lift this clinical hold and receive an FDA safe-to-procced for the IND, we believe the most critical activities will be

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to  (1)  perform  process  validation  manufacturing  runs  using  healthy  donor  material  and  (2)  ensure  qualification  of  all  assays  related  to  the  product  release.
Following completion of these activities and the earliest release of the clinical hold by FDA, we expect to enroll the first patient in a pivotal multicenter Phase 2
clinical trial in 2023.

MB-207  received  Orphan  Drug  Designation  from  the  FDA  in  September  2020.    The  FDA  also  granted  Rare  Pediatric  Disease  Designation  for  MB-207  in
August 2020. If Mustang’s BLA for MB-207 is approved, the Company may be eligible to receive a priority review voucher for this product as well, which can
also be redeemed to obtain priority review for any subsequent marketing application and may be sold or transferred. The European Medicines Agency (“EMA”)
granted Advanced Therapy Medicinal Product (“ATMP”) classification to MB-207 in April 2020 and Orphan Drug designation in April 2021.

MB-107 (newly diagnosed patients):

Interim  Phase  1/2  data  on  treatment  of  newly  diagnosed  infants  under  the  age  of  two  with  the  same  LV  vector  used  in  MB-107  were  updated  at  an  oral
presentation at the American Society of Gene & Cell Therapy (“ASGCT”) 25 th Annual Meeting held from May 16-19, 2022. The data included 23 infants with
XSCID treated with the LV vector at a median age of 3 months (range: 2 months to 14 months) with a median follow-up of 2.4 years (range: 1.4 months to 5.4
years), making it the largest known cohort of infants treated with LV gene therapy with the longest follow-up. Transduced autologous bone marrow CD34+ cells
were generated for all patients with a median vector copy number (VCN) of 0.81/cell (range: 0.16-1.81), and a median CD34+ cell dose of 9.61x106/kg (range
4.40-18.95).  Prior  to  the  infusion  of  cells,  patients  received  busulfan  targeted  to  a  cumulative  area-under-the-curve  (cAUC)  of  22  mg*hr/L.  Severe  adverse
events occurred in three patients (two patients with pancytopenia and hemolytic anemia, and one patient with delayed neutrophil engraftment), and all resolved.

Seventeen  of  18  patients  with  a  follow-up  of  >  6  months  achieved  robust  immune  reconstitution  [median  CD3+  2,545/µL,  CD4+  1,568/µL,
CD4+/CCR7+/CD45R0-  1,416/µL].    In  these  17  patients,  T  cells  matured  appropriately  as  assessed  by  normal  T  cell  receptor  excision  circles  (TRECs)  and
TCRvβ repertoire diversity and were functional as judged by phytohemagglutinin activation (“PHA”). All patients were alive with stable vector marking in all
cell lineages.  In addition, 15 patients  had  discontinued intravenous immunoglobulin, and 12 patients had  been successfully immunized.  No evidence of clonal
expansion or malignant transformation was observed.

The MB-107 timeline has been extended due to unanticipated issues related to the materials used in manufacturing. These issues were communicated to the FDA
and the Company received a written response on August 26, 2022.  The FDA response provided additional direction enabling us to effectively continue to work
with our outside suppliers. We are working towards enrolling the first patient in a pivotal multicenter Phase 2 clinical trial under our IND in 2023.

MB-107 received Orphan Drug Designation in August 2020 and Rare Pediatric Disease and Regenerative Medicine Advanced Therapy (“RMAT”) designations
in August 2019. Finally, the FDA designated MB-107 a Rare Pediatric Disease in August 2020.

The FDA grants Rare Pediatric Disease Designation for serious and life-threatening diseases that primarily affect children ages 18 years or younger and affect
fewer than 200,000 people in the United States. If Mustang’s BLA for MB-107 is approved, the Company may be eligible to receive a priority review voucher,
which  can  be  redeemed  to  obtain  priority  review  for  any  subsequent  marketing  application  and  may  be  sold  or  transferred.  This  program  is  intended  to
encourage development of new drugs and biologics for the prevention and treatment of rare pediatric diseases.

The EMA, granted Priority Medicines (“PRIME”) designation to MB-107 in July 2021, and ATMP classification to MB-107 in April 2020 and Orphan Drug
designation in November 2020.

MB-110 (Ex vivo Lentiviral Therapy for RAG1 Severe Combined Immunodeficiency (SCID))

Under an exclusive license and in partnership with LUMC, MB-110, a first-in-class ex vivo treatment for RAG1 SCID, is under development. Severe combined
immunodeficiency (“SCID”) due to complete recombinase-activating gene-1 (RAG1) deficiency is a rare, genetic disorder due to null mutations in the RAG1
gene  resulting  in  less  than  1%  of  wild  type  V(D)J  recombination  activity.  Neonatal  patients  present  with  life-threatening,  severe,  recurrent  infections  by
opportunistic fungal, viral and bacterial micro-organisms, as well as skin rashes, chronic diarrhea, failure to thrive and fever. Immunologic observations include
profound  T  and  B  cell  lymphopenia,  low  or  absent  serum  immunoglobulins,  and  normal  natural  killer  cell  counts. As  is  the  case  with  other  types  of  SCID,
RAG1-SCID is fatal in infancy unless immune reconstitution is achieved with hematopoietic stem cell transplantation (HSCT).

MB-110, which includes low-dose conditioning prior to reinfusion of the patients’ own gene-modified blood stem cells, is currently being evaluated in a Phase
1/2 multicenter clinical trial in Europe. The ongoing clinical trial has enrolled its first patient, and additional clinical

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sites are expected to be added in the near future. The RAG1-SCID program has been granted Orphan Drug Designation by the European Medicines Agency.

Mustang also established an ongoing partnership with Frank J. Staal, Ph.D., professor of Molecular Stem Cell Biology and molecular immunologist at LUMC,
whose laboratory developed the MB-110 therapy. Dr. Staal will continue the development of additional LV gene therapies in his lab, to which Mustang Bio has
rights under the agreement.

INTELLECTUAL PROPERTY AND PATENTS

General

Our goal is to obtain, maintain and enforce patent protection for our products, formulations, processes, methods and other proprietary technologies, preserve our
trade secrets, and operate without infringing on the proprietary rights of other parties, both in the U.S. and in other countries. Our policy is to actively seek to
obtain, where appropriate, the broad intellectual property protection for our product candidates, proprietary information and proprietary technology through a
combination of contractual arrangements and patents, both in the U.S. and elsewhere in the world.

We  also  depend  upon  the  skills,  knowledge  and  experience  of  our  scientific  and  technical  personnel,  as  well  as  that  of  our  advisors,  consultants  and  other
contractors (“know-how”). To help protect our proprietary know-how which is not patentable, and for inventions for which patents may be difficult to enforce,
we rely on trade secret protection and confidentiality agreements to protect our interests. To this end, we require all employees, consultants, advisors and other
contractors  to  enter  into  confidentiality  agreements  which  prohibit  the  disclosure  of  confidential  information  and,  where  applicable,  require  disclosure  and
assignment to us of the ideas, developments, discoveries and inventions that they generate or make, and which are important to our business.

Patents and other proprietary rights are crucial to the development of our business. We will be able to protect our proprietary technologies from unauthorized
use  by  third  parties  only  to  the  extent  that  our  proprietary  rights  are  covered  by  valid  and  enforceable  patents,  supported  by  regulatory  exclusivity  or  are
effectively maintained as trade secrets. We have a few patents and patent applications related to our compounds and other technology, but we cannot guarantee
the scope of protection of the issued patents, or that such patents will survive a validity or enforceability challenge, or that any of the pending patent applications
will issue as patents.

Generally, patent applications in the U.S. are maintained in secrecy for a period of 18 months or more. The patent positions of biotechnology and pharmaceutical
companies are highly uncertain and involve complex legal and factual questions. Therefore, we cannot predict the breadth of claims allowed in biotechnology
and  pharmaceutical  patents,  or  their  enforceability.  To  date,  there  has  been  no  consistent  policy  regarding  the  breadth  of  claims  allowed  in  biotechnology
patents.  Third  parties  or  competitors  may  challenge  or  circumvent  our  patents  or  patent  applications,  if  issued.  If  our  competitors  prepare  and  file  patent
applications  in  the  U.S.  that  claim  technology  also  claimed  by  us,  we  may  have  to  participate  in  interference  or  derivation  proceedings  declared  by  the  U.S.
Patent and Trademark Office (“USPTO”) to determine priority of invention, which could result in substantial cost, even if the eventual outcome is favorable to
us. Because of the extensive time required for development, testing and regulatory review of a potential product, it is possible that before we commercialize any
of our products, any related patent may expire or remain in existence for only a short period following commercialization, thus reducing any advantage of the
patent.  However,  the  life  of  a  patent  covering  a  product  that  has  been  subject  to  regulatory  approval  may  have  the  ability  to  be  extended  through  the  patent
restoration program, although any such extension could still be minimal. Additionally, statutory caps impose further limitation on any such extensions.

If  a  patent  is  issued  to  a  third  party  containing  one  or  more  preclusive  or  conflicting  claims,  and  those  claims  are  ultimately  determined  to  be  valid  and
enforceable,  we  may  be  required  to  obtain  a  license,  if  available,  under  such  patent  or  to  develop  or  obtain  alternative  technology.  In  the  event  of  litigation
involving a third party claim, an adverse outcome in the litigation could subject us to significant liabilities to such third party, require us to seek a license for the
disputed rights from such third party, and/or require us to cease use of the technology. Further, our breach of an existing license or failure to obtain a license to
technology required to commercialize our products may seriously harm our business. We also may need to commence litigation to enforce any patents issued to
us or to determine the scope and validity of third party proprietary rights. Litigation would not only involve substantial costs but would also involve substantial
time commitments on the part of our key executives and research and development personnel.

In March 2015, we licensed intellectual property related to CAR T technology from COH. The portfolio of rights licensed from COH now includes patents and
application  directed  to  CARs  targeting  IL13Rα2,  CD123,  CS1,  HER2,  and  PSCA,  as  well  as  rights  related  to  modified  CAR  hinge  regions  and  methods  of
preparing CAR T cells in particular subpopulations of cell and administering CAR T cells. The intellectual property licensed thereunder relating to IL13Rα2-
targeting CARs includes granted patents in the U.S., Australia, China, Europe,

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Russia, Japan, Hong Kong, Israel, and Mexico, and this patent family further includes pending applications in the U.S., Australia, Brazil, Canada, China, Europe,
South  Korea,  Russia,  Japan,  Israel,  Mexico,  and  New  Zealand. Any  patents  issuing  from  the  IL13Rα2-targeting  CAR  will  expire  no  sooner  than  2035.  The
licensed intellectual property relating to relating to CD123-targeting CARs includes issues patents in the U.S., China, Europe, Hong Kong, Israel, Japan, South
Korea, and Mexico, and this patent family further includes pending applications in the U.S., Australia, Brazil, China, Europe, Hong Kong, Israel, Japan, South
Korea,  Mexico,  and  New  Zealand. Any  patents  issuing  from  the  CD123-targeting  CAR  will  expire  no  sooner  than  2033.  The  licensed  intellectual  property
relating to relating to CS1-targeting CARs includes issues patents in the U.S., Australia, Israel, and Russia, as well as pending applications in the U.S., Australia,
Brazil, Canada, China, Europe, Hong Kong, Israel, South Korea, Mexico, Japan, Russia, and New Zealand. Any patents issuing from the CS1-targeting CAR
will expire no sooner than 2035, and some patents relating to particular methods involving CS1-targeting CARs will expire no sooner than 2038. The licensed
intellectual  property  relating  to  relating  to  HER2-targeting  CARs  includes  issues  patents  in  Japan  and  Russia,  as  well  as  pending  applications  in  the  U.S.,
Australia,  Brazil,  Canada,  China,  Europe,  Hong  Kong,  Israel,  Japan,  South  Korea,  Russia,  Mexico,  and  New  Zealand. Any  patents  issuing  from  the  HER2-
targeting CAR will expire no sooner than 2036. The licensed intellectual property relating to relating to PSCA-targeting CARs includes issues patents in Europe
and Hong Kong, as well as pending applications in the U.S., Australia, Brazil, Canada, China, Europe, Hong Kong, Israel, Japan, South Korea, Russia, and New
Zealand.  The  licensed  intellectual  property  relating  to  relating  modified  CAR  hinge  regions  includes  issues  patents  in  China,  Europe,  and  Japan,  as  well  as
pending applications in the U.S., Australia, China, and Europe. The patents issuing from the modified CAR hinge region family will expire no sooner than 2034.
The licensed intellectual property relating to relating to method of preparing or administering CAR T cells includes issues patents in China, Europe, and Japan,
as well as pending applications in the U.S., Australia, Brazil, Canada, China, Europe, Hong Kong, Japan, Israel, Mexico, Russia, and New Zealand. The patents
relating to these technologies will expire no sooner than 2035 or, in the case of the administration methods, 2036.

Also, in March 2015, we executed a sponsored research agreement with COH, pursuant to which research is performed in the laboratory of Drs. Stephen Forman
and Christine Brown. The sponsored research agreement gives us the right to first negotiation under specified maximum terms regarding any future inventions
arising from the laboratory.

In  May  2017,  we  licensed  intellectual  property  related  to  CAR  T  technology  for  targeting  CD20  from  Fred  Hutch.  The  intellectual  property  includes  an
international  application  under  the  Patent  Cooperation  Treaty  (i.e.,  a  PCT  application),  which  has  now  matured  into  several  issued  patents,  including  issued
patents in the U.S. and Europe, as well as pending applications in the U.S., Australia, Brazil, Canada, China, Europe, Hong Kong, Israel, Japan, South Korea,
Mexico, New Zealand, and Russia. These applications contain claims relating to various CD20-targeting CAR constructs and CAR T cells, as well as methods of
making  and  using  the  same.  The  national  stage  applications  claiming  priority  to  the  PCT  application  were  filed  in  May  2018  in  order  to  begin  substantive
examination of the claims. Patents maturing from these national stage applications will expire no sooner than March 2037.

In March 2017, we licensed intellectual property related to antibodies and binding agents that specifically bind to PSCA from the University of California Los
Angeles  (“UCLA”).  The  intellectual  property  includes  multiple  granted  patents  and  pending  applications  from  around  the  world  including  the  U.S.,  Europe,
Japan, China, and Canada. The granted patents and patents maturing from the pending applications will expire no sooner than March 2027.

In August  2018,  we  licensed  from  St.  Jude  Children’s  Research  Hospital  XSCID  Technology  related  to  an ex vivo  lentiviral  vector  gene  therapy  program  to
provide a normal copy of the IL2RG gene to patients born with XSCID.

In February 2019, we licensed Material and Technical Information related to the HSV-1 oncolytic virus C134 from Nationwide in Columbus, Ohio.

In August 2019, we licensed from CSL Behring (Calimmune) the CytegrityTM stable producer cell line developed and used by St. Jude. The CytegrityTM stable
producer cell line will be used to produce the viral vector for MB-107.

In September 2020, we entered into an exclusive, worldwide licensing agreement with SIRION Biotech for the rights to SIRION’s LentiBOOSTTM technology
for the development of MB-207. This license includes right to granted patents and pending applications in the U.S., Europe, Japan, and Israel. In December 2021
this licensing agreement was amended to include CD20-directed CAR Ts in addition to lentiviral stem cell gene therapy for the treatment of XSCID.

In  November  2021,  we  entered  into  an  exclusive,  worldwide  licensing  agreement  with  Leiden  University  Medical  Centre  for  a  first-in-class ex vivo  lentiviral
gene therapy for the treatment of RAG1 severe combined immunodeficiency (“RAG1-SCID”).

In August 2021, we entered into an exclusive license agreement with Mayo Clinic for a novel technology that may be able to transform the administration of
CAR T therapies and potentially allow such therapies to be used as an off-the-shelf therapy.

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In addition to the technology the Company has in-licensed, Mustang has also developed its own proprietary intellectual property, both alone and in conjunction
with COH. In particular, Mustang filed a U.S. provisional application directed to optimized methods for manufacturing cell-based therapeutics, and Mustang and
COH, as co-applicants, filed a U.S. provisional application directed to methods of treating hematological cancers.

In addition to the technology the company has in-licensed, Mustang has also developed its own proprietary intellectual property, both alone and in conjunction
with COH. In particular, Mustang owns pending applications in the U.S. and Europe directed to methods for manufacturing cell-based therapeutics, and pending
applications in the U.S., Taiwan, and PCT relating to anti-idiotype antibodies. Mustang and COH also own as co-applicants pending application in the U.S.,
Taiwan, and PCT directed to methods of treating hematological cancers with a combination therapy.  

Other Intellectual Property Rights

We depend upon trademarks, trade secrets, knowhow and continuing technological advances to develop and maintain our competitive position. To maintain the
confidentiality of trade secrets and proprietary information, we require our employees, scientific advisors, consultants and collaborators, upon commencement of
a relationship with us, to execute confidentiality agreements and, in the case of parties other than our research and development collaborators, to agree to assign
their inventions to us. These agreements are designed to protect our proprietary information and to grant us ownership of technologies that are developed in
connection with their relationship with us. These agreements may not, however, provide protection for our trade secrets in the event of unauthorized disclosure
of such information.

In  addition  to  patent  protection,  we  may  utilize  orphan  drug  regulations  or  other  provisions  of  the  Food,  Drug  and  Cosmetic Act  of  1938,  as  amended  (the
“FDCA”), to provide market exclusivity for certain of our product candidates. Orphan drug regulations provide incentives to pharmaceutical and biotechnology
companies to develop and manufacture drugs for the treatment of rare diseases, currently defined as diseases that exist in fewer than 200,000 individuals in the
U.S., or diseases that affect more than 200,000 individuals in the U.S. but for which the sponsor does not realistically anticipate will generate a net profit. Under
these provisions, a manufacturer of a designated orphan drug can seek tax benefits, and the holder of the first approval of a designated orphan product from the
FDA will be granted a seven-year period of marketing exclusivity for such FDA approved orphan product.

LICENSE, CLINICAL TRIAL AND SPONSORED RESEARCH AGREEMENTS

St. Jude Children’s Research Hospital

XSCID License

On August 2, 2018, the Company entered into an exclusive worldwide license agreement with St. Jude for the development of a first-in-class ex vivo lentiviral
gene therapy for the treatment of XSCID. The Company paid $1.0 million in consideration for the exclusive license in addition to an annual maintenance fee of
$0.1  million  (beginning  in  2019).  St.  Jude  is  eligible  to  receive  payments  totaling  $13.5  million  upon  the  achievement  of  five  development  and
commercialization milestones. Royalty payments in the mid-single digits are due on net sales of licensed products.

XSCID Non-interventional Services Agreement

In  December  2019,  the  Company  entered  into  a  Non-Interventional  Services Agreement  with  Children's  CGMP,  LLC  ("Children’s"),  an  affiliate  of  St.  Jude
Children's  Research  Hospital,  pursuant  to  which  Children’s  provides  lentiviral  vector  for  non-clinical  XSCID  research  purposes,  as  well  as  related  advisory
services. Pursuant to the agreement, we agreed to fund approximately $0.8 million upon execution of the agreement.

XSCID Data Transfer Agreement

In June 2020, the Company entered into a Data Transfer Agreement for the XSCID program (the “XSCID DTA”). Pursuant to the terms of the XSCID DTA, we
made an upfront payment of approximately $1.1 million and will reimburse St. Jude for additional costs in connection with the on-going investigator-initiated
study.

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City of Hope

In February 2017, the Company and COH amended and restated their license agreement, dated March 17, 2015 (the “Original Agreement”), by entering into
three separate amended and restated exclusive license agreements, one relating to the CD123-directed CAR T program, one relating to the IL13Rα2-directed
CAR T program, and one relating to the Spacer technology (described below). The total potential consideration payable to COH by the Company, in equity or
cash, did not in the aggregate change materially from the Original Agreement. As of December 31, 2022, COH owns 845,385 shares of Class A common stock
representing approximately 0.8% of ownership, and has the right to appoint a director to the Board of Directors (the “Board”). The Company considers COH to
be a related party, due to the foregoing rights and ownership, as well as the high proportion of the Company’s assets that are licensed from COH.

In addition, the Company entered into a sponsored research agreement with COH under which the Company has funded continued research in the amount of
$2.0  million  per  year,  payable  in  four  equal  installments,  which  ended  in  the  first  quarter  of  2020.  The  research  covered  under  this  arrangement  is  for  the
IL13Rα2-directed CAR T program, the CD123-directed CAR T program, and the Spacer technology.

CD123 License

In February 2017, the Company entered into an Amended and Restated Exclusive License Agreement with COH to acquire intellectual property rights pertaining
to patent rights related to the CD123-directed CAR T program (the “CD123 License”). Pursuant to the CD123 License, the Company and COH acknowledged
that  an  upfront  fee  had  already  been  paid  under  the  Original Agreement.  In  addition,  COH  is  eligible  to  receive  an  annual  maintenance  fee  of  $25,000  and
milestone payments totaling up to approximately $14.5 million, upon and subject to the achievement of certain milestones. Royalty payments in the mid-single
digits are due on net sales of licensed products. The Company is obligated to pay COH a percentage of certain revenues received in connection with a sublicense
ranging from the mid-teens to mid-thirties, depending on the timing of the sublicense in the development of any product. In addition, equity grants made under
the Original Agreement were acknowledged, and the anti-dilution provisions of the Original Agreement were carried forward.

CD123 CRA (AML and BPDCN)

In February 2017, the Company entered into a Clinical Research Support Agreement for CD123-directed CAR T program (the “CD123 CRA”). Pursuant to the
terms of the CD123 CRA, the Company made an upfront payment of approximately $19,000 and will contribute an additional $97,000 per patient in connection
with the on-going investigator-initiated study. Further, the Company agreed to fund approximately $76,000 annually pertaining to the clinical development of
the CD123-directed CAR T therapy.

IL13Rα2 License

In February 2017, the Company entered into an Amended and Restated Exclusive License Agreement with COH to acquire intellectual property rights pertaining
to  patent  rights  related  to  the  IL13Rα2-directed  CAR  T  program  (the  “IL13Rα2  License”).  Pursuant  to  the  IL13Rα2  License,  the  Company  and  COH
acknowledged that an upfront fee had already been paid under the Original Agreement. In addition, COH is eligible to receive an annual maintenance fee of
$25,000 and milestone payments totaling up to approximately $14.5 million, upon and subject to the achievement of certain milestones. Royalty payments in the
mid-single digits are due on net sales of licensed products. The Company is obligated to pay COH a percentage of certain revenues received in connection with a
sublicense ranging from the mid-teens to mid-thirties, depending on the timing of the sublicense in the development of any product. In addition, equity grants
made under the Original Agreement were acknowledged, and the anti-dilution provisions of the Original Agreement were carried forward.

IL13Rα2 CRA (Glioblastoma)

In February 2017, the Company entered into a Clinical Research Support Agreement for the IL13Rα2-directed CAR T program (the “IL13Rα2 GBM CRA”).
Pursuant to the terms of the IL13Rα2 CRA, the Company made an upfront payment of approximately $9,000 and will contribute an additional $140,000 per
patient  in  connection  with  the  on-going  investigator-initiated  study.  Further,  the  Company  agreed  to  fund  approximately  $66,000  annually  pertaining  to  the
clinical development of the IL13Rα2-directed CAR T therapy.

IL13Rα2 CRA (Leptomeningeal Glioblastoma)

In  October  2020,  the  Company  entered  into  a  Clinical  Research  Support  Agreement  for  the  IL13Rα2-directed  CAR  T  program  for  adult  patients  with
leptomeningeal glioblastoma, ependymoma or medulloblastoma (the “IL13Rα2 Leptomeningeal CRA”). Pursuant to the terms of the IL13Rα2 Leptomeningeal
CRA, the Company made an upfront payment of approximately $29,000 and will contribute an additional

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$150,000  per  patient  in  connection  with  the  on-going  investigator-initiated  study.  Further,  the  Company  agreed  to  fund  approximately  $200,000  annually
pertaining to the clinical development of the IL13Rα2-directed CAR T therapy.

Sponsored Research Agreement - IL13Rα2 and C134 Combination

In October 2020, the Company entered into a Sponsored Research Agreement (“SRA”) with COH to conduct combination studies of a potential IL13Rα2 CAR
and C134 oncolytic virus therapy. Pursuant to the SRA, the Company funded research in the amount of $0.3 million for the program. In November 2022, the
SRA was amended to include additional funding of $0.6 million.

Spacer License

In February 2017, the Company entered into an Amended and Restated Exclusive License Agreement with COH to acquire intellectual property rights pertaining
to patent rights related to Spacer (the “Spacer License”). Pursuant to the Spacer License, the Company and COH acknowledged that an upfront fee had already
been paid under the Original Agreement. In addition, COH will receive an annual maintenance fee of $10,000. No royalties are due if the Spacer technology is
used in conjunction with a CD123 CAR or an IL13Rα2 CAR, and royalty payments in the low single digits are due on net sales of licensed products if the Spacer
technology  is  used  in  conjunction  with  other  intellectual  property.  The  Company  is  obligated  to  pay  COH  a  percentage  of  certain  revenues  received  in
connection with a sublicense in the mid-thirties, but no such payments are due in connection with sublicenses that are granted in conjunction with the sublicense
of other CARs that are licensed from COH to the Company. In addition, equity grants made under the Original Agreement were acknowledged, and the anti-
dilution provisions of the Original Agreement were carried forward.

IV/ICV License

In February 2017, the Company entered into an exclusive license agreement (the “IV/ICV License”) with COH to acquire intellectual property rights in patent
applications  related  to  the  intraventricular  and  intracerebroventricular  methods  of  delivering  T  cells  that  express  CARs.  Pursuant  to  the  IV/ICV  License,  in
March 2017, the Company paid COH an upfront fee of $0.1 million. COH is eligible to receive a milestone payment totaling approximately $0.1 million, upon
and  subject  to  the  achievement  of  a  milestone,  and  an  annual  maintenance  fee.  Royalty  payments  in  the  low  single  digits  are  due  on  net  sales  of  licensed
products.  The  Company  is  obligated  to  pay  COH  a  percentage  of  certain  revenues  received  in  connection  with  a  sublicense  in  the  mid-thirties,  but  no  such
payments are due in connection with sublicenses that are granted in conjunction with the sublicense of other CAR T programs that are licensed from COH to the
Company.

HER2 Technology License

On  May  31,  2017,  the  Company  entered  into  an  exclusive  license  agreement  (the  “HER2 Agreement”)  with  COH  for  the  use  of  HER2  CAR  T  technology
(“HER2 Technology”), which is currently being applied in the treatment of glioblastoma multiforme and in the treatment of HER2+ cancers – in particular breast
cancer  –  that  have  metastasized  to  the  brain.  Pursuant  to  the  HER2  Agreement,  the  Company  paid  an  upfront  fee  of  $0.6  million  and  owes  an  annual
maintenance fee of $50,000 (which began in 2019). In addition, COH is eligible to receive milestone payments totaling up to $14.9 million, upon and subject to
the achievement of certain milestones. Royalty payments in the mid-single digits are due on net sales of licensed products. The Company is obligated to pay
COH  a  percentage  of  certain  revenues  received  in  connection  with  a  sublicense  ranging  from  the  mid-teens  to  mid-thirties,  depending  on  the  timing  of  the
sublicense in the development of any product.

HER2 CRA (HER2+ glioblastoma and HER2+ brain metastases)

In September 2020, the Company entered into a Clinical Research Support Agreement for the HER2-directed CAR T program (the “HER2 CRA”). Pursuant to
the  terms  of  the  HER2  CRA,  the  Company  made  an  upfront  payment  of  approximately  $29,000  and  will  contribute  an  additional  $150,000  per  patient  in
connection  with  the  on-going  investigator-initiated  study.  Further,  the  Company  agreed  to  fund  approximately  $200,000  annually  pertaining  to  the  clinical
development of the HER2-directed CAR T therapy.

CS1 Technology License

On May 31, 2017, the Company entered into an exclusive license agreement (the “CS1 Agreement”) with COH for the use of CS1-specific CAR T technology
(“CS1 Technology”), which is currently being applied in the treatment of multiple myeloma. Pursuant to the CS1 Agreement, the Company paid an upfront fee
of $0.6 million and owes an annual maintenance fee of $50,000 (which began in 2019). In addition, COH is eligible to receive milestone payments totaling up to
$14.9 million, upon and subject to the achievement of certain milestones. Royalty payments in the mid-single digits are due on net sales of licensed products. The
Company is obligated to pay COH

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a percentage of certain revenues received in connection with a sublicense ranging from the mid-teens to mid-thirties, depending on the timing of the sublicense in
the development of any product.

CS1 CRA (multiple myeloma)

In June 2020, the Company entered into a Clinical Research Support Agreement for the CS1-directed CAR T program (the “CS1 CRA”). Pursuant to the terms of
the CS1 CRA, the Company made an upfront payment of approximately $32,000 and will contribute an additional $130,000 per patient in connection with the
on-going investigator-initiated study. Further, the Company agreed to fund approximately $200,000 annually pertaining to the clinical development of the CS1-
directed CAR T therapy.

PSCA Technology License

On  May  31,  2017,  the  Company  entered  into  an  exclusive  license  agreement  (the  “PSCA Agreement”)  with  COH  for  the  use  of  PSCA  CAR  T  technology
(“PSCA  Technology”),  which  is  currently  being  applied  in  the  treatment  of  PSCA+  metastatic  castration-resistant  prostate  cancer.  Pursuant  to  the  PSCA
Agreement,  the  Company  paid  an  upfront  fee  of  $0.3  million  and  owes  an  annual  maintenance  fee  of  $50,000  (which  began  in  2019).  In  addition,  COH  is
eligible to receive milestone payments totaling up to $14.9 million, upon and subject to the achievement of certain milestones. Royalty payments in the mid-
single digits are due on net sales of licensed products. The Company is obligated to pay COH a percentage of certain revenues received in connection with a
sublicense ranging from the mid-teens to mid-thirties, depending on the timing of the sublicense in the development of any product.

PSCA CRA

In October 2020, the Company entered into a Clinical Research Support Agreement for the PSCA-directed CAR T program (the “PSCA CRA”). Pursuant to the
terms of the PSCA CRA, the Company made an upfront payment of $33,000 and will contribute an additional $125,000 per patient in connection with the on-
going investigator-initiated study. Further, the Company agreed to fund approximately $200,000 annually pertaining to the clinical development of the PSCA-
directed CAR T therapy.

Manufacturing License

On  January  3,  2018,  the  Company  entered  into  a  non-exclusive  license  agreement  with  COH  to  acquire  patent  and  licensed  know-how  rights  related  to
developing,  manufacturing,  and  commercializing  licensed  products.  The  Company  paid  $75,000  in  consideration  for  the  licenses  to  the  patent  rights  and  the
licensed know-how in addition to an annual maintenance fee. Royalty payments in the low-single digits are due on net sales of licensed products.

Sponsored Research Agreement - Manufacturing

On  January  3,  2018,  the  Company  entered  into  an  SRA  with  COH  to  optimize  and  develop  CAR  T  cell  processing  procedures.  Pursuant  to  the  SRA,  the
Company funded continued research in the amount of $0.9 million for the program, with an initial term of two (2) years. The SRA expired in January 2020.

University of California License

On March 17, 2017, the Company entered into an exclusive license agreement with the Regents of UCLA (the “UCLA License”) to acquire intellectual property
rights  in  patent  applications  related  to  the  engineered  anti-prostate  stem  cell  antigen  antibodies  for  cancer  targeting  and  detection.  Pursuant  to  the  UCLA
License, the Company paid UCLA the upfront fee of $0.2 million and owes an annual maintenance fee of $15,000 for the first two years, $25,000 for years
three and four, and $50,000 per year thereafter. In addition, UCLA is eligible to receive milestone payments totaling up to $14.3 million, upon and subject to the
achievement of certain milestones. Royalty payments in the mid-single digits are due on net sales of licensed products.

Fred Hutchinson Cancer Center

CD20 Technology License

Effective July 3, 2017, Mustang entered into an exclusive, worldwide licensing agreement with Fred Hutch for the use of a CAR T therapy related to autologous
T  cells  engineered  to  express  a  CD20-specific  CAR  (the  “CD20  Technology  License”).  Pursuant  to  the  CD20  Technology  License,  the  Company  paid  Fred
Hutch an upfront fee of $0.3 million and owes an annual maintenance fee of $50,000 on each

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anniversary of the license until the achievement by the Company of regulatory approval of a licensed product using the CD20 Technology. Additional payments
are due for the achievement of eleven development milestones totaling $39.1 million. Royalty payments in the mid-single digits are due on net sales of licensed
products.

CD20 CTA (NHL and CLL)

Also, on July 3, 2017, in conjunction with the CD20 Technology License from Fred Hutch, Mustang entered into an investigator-initiated clinical trial agreement
(the “CD20 CTA”) to provide partial funding for a Phase 1/2 clinical trial at Fred Hutch evaluating the safety and efficacy of the CD20 Technology in patients
with relapsed or refractory B-cell non-Hodgkin lymphomas (“NHLs”). In connection with the CD20 CTA, the Company agreed to fund up to $5.3 million of
costs associated with the clinical trial, which commenced during the fourth quarter of 2017.

In November 2020, the CD20 CTA was amended to include additional funding of approximately $1.8 million for the treatment of five patients with chronic
lymphocytic  leukemia  (“CLL”)  and  other  research  costs.  In  January  2022,  the  CTA  was  amended  to  increase  funding  by  approximately  $2.2  million  for  the
treatment of additional patients.

Sponsored Research Agreement

On March 17, 2018, the Company entered into an SRA with Fred Hutch related to developing and optimizing processes and systems associated with CD20 cell
processing.  Pursuant  to  the  SRA,  the  Company  funded  continued  research  in  the  amount  of  $0.6  million  during  the  term  of  the  SRA,  which  expired  in
March 2019.

Nationwide Children’s Hospital License

On February 20, 2019, the Company entered into an exclusive worldwide license agreement with Nationwide for the development of an oncolytic virus (referred
to  by  Nationwide  as  C134;  now  referred  to  by  the  Company  as  MB-108)  for  the  treatment  of  glioblastoma  multiforme.  The  Company  paid  $0.2  million  in
consideration for the exclusive license. Nationwide is eligible to receive additional payments totaling $77.5 million upon the achievement of ten development
and commercialization milestones. Royalty payments in the low-single digits are due on net sales of licensed products.

CSL Behring (Calimmune) License

On August 23, 2019, the Company entered into a non-exclusive license agreement with CSL Behring (Calimmune) for the CytegrityTM stable producer cell line
for the production of lentiviral gene therapy for the XSCID gene therapy program. The CytegritTM stable producer cell line will be used to produce the viral
vector for Mustang’s MB-107 and MB-207 lentiviral gene therapies for the treatment of XSCID. The Company paid $0.2 million in consideration for the license.
CSL Behring (Calimmune) is eligible to receive additional payments totaling $1.2 million upon the achievement of three development and commercialization
milestones. Royalty payments in the low-single digits are due on net sales of licensed products.

SIRION Biotech License

On October 6, 2020, the Company announced a licensing agreement under which we acquired technology rights from SIRION Biotech GmbH (“SIRION”) for
LentiBOOST™  technology  for  the  development  of  MB-207,  Mustang’s  lentiviral  gene  therapy  for  the  treatment  of  patients  with  XSCID,  who  have  been
previously treated with a hematopoietic stem cell transplantation (“HSCT”) and for whom re-treatment is indicated. LentiBOOST™ is SIRION’s proprietary
non-cytotoxic transduction enhancer for lentiviral vectors.

Pursuant to the agreement, the Company paid SIRION a one-time upfront fee of $0.1 million. In addition, SIRION is eligible to receive additional payments
totaling up to approximately $9.1 million upon the achievement of certain development and commercialization milestones. Royalty payments in the low- to mid-
single digits are due on aggregate cumulative worldwide net sales of licensed products.

In December 2021 this licensing agreement was amended to include CD20-directed CAR Ts. SIRION is eligible to receive additional payments totaling up to
approximately $9.1 million upon the achievement of certain development and commercialization milestones for the additional product.

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Minaris Regenerative Medicine Agreement

On November 23, 2020, we announced an agreement with Minaris Regenerative Medicine GmbH (“Minaris”) to enable technology transfer and GMP clinical
manufacturing in Europe of our MB-107 lentiviral gene therapy program for the treatment of XSCID. Under the terms of the agreement, Minaris will perform
technology transfer of the manufacturing and analytical processes, as well as their adoption to the European regulatory environment, for the GMP-compliant
manufacturing  of  the  drug  product  at  its  site  in  Ottobrunn,  Germany,  with  the  goal  of  supplying  clinical  trials  in  Europe.  In  2022,  the  Company  made  the
decision to delay the technology transfer and clinical manufacturing processes.

Mayo Clinic

CAR T Technology License

On August 12, 2021, we announced that the Company has executed an exclusive license agreement with Mayo Clinic for a novel technology that may be able to
transform the administration of CAR T therapies and potentially allow such therapies to be used as an off-the-shelf therapy.

The technology, developed by Larry R. Pease, Ph.D., principal investigator and former director of the Center for Immunology and Immune Therapies at Mayo
Clinic, is a new platform to administer CAR T therapy using a two-step approach. First, a peptide is administered to the patient to drive the proliferation of the
patient’s resident T cells. This is followed by the administration of a viral CAR construct directly into the lymph nodes of the patient. In turn, the viral construct
infects the activated T cells and effectively forms CAR T cells in vivo in the patient. Successful implementation may lead to an off-the-shelf product with no
need to isolate and expand patient T cells ex vivo.

Preclinical  proof-of-concept  has  been  established,  and  the  ongoing  development  of  this  technology  will  take  place  at  Mayo  Clinic.  Mustang  plans  to  file  an
Investigational New Drug (“IND”) application for a multicenter Phase 1 clinical trial once a lead construct has been identified.

Pursuant to this agreement, the Company paid an upfront fee of $0.8 million and will pay an annual maintenance fee of $25,000. Additional payments are due
for each of two licensed products for the achievement of eleven development and commercial milestones totaling up to $92.6 million per product, and royalty
payments in the mid-single digits as a percentage of revenue are due on net sales of licensed products.

Sponsored Research Agreement

In connection with the Mayo Clinic license agreement, the Company entered into an SRA under which the Company will fund research in the amount of $2.1
million over a period of two years. In October 2022, the SRA was amended to include additional funding of $0.1 million. The research performed pursuant to
this agreement will support the technology the Company has licensed from Mayo Clinic.

Leiden University Medical Centre

RAG1-SCID Technology License

On November 10, 2021, we announced an exclusive license agreement with Leiden University Medical Centre (“LUMC”) for a first-in-class ex vivo lentiviral
gene therapy for the treatment of RAG1 severe combined immunodeficiency (“RAG1-SCID”).

Pursuant  to  this  agreement,  the  Company  paid  an  upfront  fee  of  $0.4  million. Additional  payments  are  due  for  the  achievement  of  five  development  and
commercial  milestones  totaling  up  to  $31.0  million,  and  royalty  payments  in  the  low  to  mid-single  digits  as  a  percentage  of  revenue  are  due  on  net  sales  of
licensed products.

Sponsored Research Agreement

In connection with the RAG1-SCID license, the Company entered into an SRA with LUMC under which the Company will fund research in the amount of 2.3
million euros over a period of five years. The research performed pursuant to this agreement will support the technology the Company has licensed from LUMC.

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COMPETITION

Competition in the pharmaceutical and biotechnology industries is intense. Our competitors include pharmaceutical companies and biotechnology companies, as
well  as  universities  and  public  and  private  research  institutions.  In  addition,  companies  that  are  active  in  different  but  related  fields  represent  substantial
competition  for  us.  Many  of  our  competitors  have  significantly  greater  capital  resources,  larger  research  and  development  staffs  and  facilities  and  greater
experience in drug development, regulation, manufacturing and marketing than we do. These organizations also compete with us to recruit qualified personnel,
attract partners for joint ventures or other collaborations, and license technologies that are competitive with ours. To compete successfully in this industry, we
must identify novel and unique drugs or methods of treatment and then complete the development of those drugs as treatments in advance of our competitors.

The drugs that we are attempting to develop will have to compete with existing therapies. In addition, a large number of companies are pursuing the development
of pharmaceuticals that target the same conditions that we are targeting. Other companies have products or product candidates in various stages of pre-clinical or
clinical development, or with marketing approvals, to treat conditions for which we are also seeking to discover and develop product candidates. Some of these
potential competing drugs are further advanced in development than our product candidates and may be commercialized earlier.

The field of CAR T therapy is extremely active. Companies and partnerships currently engaged in clinical trials with CAR T modalities include Bristol Myers
Squibb, Novartis Pharmaceuticals/University of Pennsylvania, 2seventy bio, Allogene Therapeutics, Cellectis, Gilead Sciences, Bellicum Pharmaceuticals, MD
Anderson/Ziopharm Oncology, Atara Biotherapeutics, Celyad, Autolus Therapeutics, Precigen Inc., Precision BioSciences, Adicet Bio, Cargo Therapeutics, and
ImmPACT Bio.

The gene therapy field is characterized by rapidly changing technologies, significant competition and a strong emphasis on intellectual property. We are aware of
companies  currently  engaged  in  developing  gene  therapies  in  various  indications,  including  Abeona  Therapeutics,  Adverum  Biotechnologies,  Astellas,
AVROBIO, Axovant Sciences, Biogen, bluebird bio, BioMarin Pharmaceutical, Homology Medicines, Krystal Biotech, MeiraGTx, Novartis Pharmaceuticals,
Orchard Therapeutics, Passage Bio, Prevail Therapeutics, REGENXBIO, Rocket Pharmaceuticals, Roche, Sangamo Therapeutics, Sarepta Therapeutics, Solid
Biosciences,  Ultragenyx  Pharmaceuticals,  uniQure  and  Voyager  Therapeutics,  as  well  as  several  companies  addressing  other  methods  for  delivering  or
modifying genes and regulating gene expression.

EMPLOYEES

As of December 31, 2022, we had 113 full and part-time employees. None of our employees are represented by a labor union or covered under a collective
bargaining  agreement  and  we  consider  our  employee  relations  to  be  good.  Employees  of  Fortress  also  make  valuable  financial,  legal,  scientific  and  other
strategic contributions to Mustang on a regular basis.

SUPPLY AND MANUFACTURING

As  an  early  stage  development  company,  we  rely  on  our  research  partners  to  manufacture  or  have  manufactured  all  lentiviral  vectors  used  in  the  clinical
development  programs  currently  in  progress  at  COH,  Fred  Hutch,  St.  Jude,  the  NIH,  and  LUMC  under  the  IND  applications  filed  by  these  institutions.  In
addition we rely on the NIH to produce oncolytic virus for UAB, the clinical trial site for the Phase 1 trial of Nationwide’s C134 oncolytic virus (MB-108). We
will continue to rely on our research partners to manufacture lentiviral vectors and oncolytic virus for Mustang-IND trials until such time as material is available
from our contract manufacturing organizations.

Pursuant  to  the  March  2015  Licensing  Agreement  with  COH,  we  have  the  right  to  make  and  have  made  the  cellular  products,  and  we  have  negotiated
Investigator-Initiated Clinical Research Support Agreements with COH and Fred Hutch which specify the cell processing costs and numbers of patients which
will be supplied under filed protocols. Our research partners have extensive experience manufacturing clinical materials for development studies, but we are
currently dependent on both their capacity limitations and continued operating success to manufacture viral vector and to process cells for all CAR T clinical
trials for which these partners hold the INDs, as well as to have manufactured oncolytic virus for the MB-108 investigator-IND clinical trial being conducted at
UAB.

We  have  limited  experience  in  processing  cells  for  clinical  or  commercial  purposes.  In  2018  we  opened  our  own  cell  processing  facility  in  Worcester,
Massachusetts, in order to manufacture and supply cellular product candidates for all clinical trials that will be conducted under IND applications to be filed by
us. In August 2019, the FDA approved our IND application to initiate a multi-center Phase 1/2 clinical trial of MB-102 (CD123 CAR T) and in January 2021,
the  FDA  approved  our  IND  application  to  initiate  a  multi-center  Phase  2  clinical  trial  of  MB-107  (XSCID).  In  May  2021,  the  FDA  approved  our  IND
application to initiate a multi-center Phase 1/2 clinical trial of MB-106 (CD-

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20). As with any supply program, obtaining raw materials of the correct quality cannot be guaranteed, and we cannot ensure that we will be successful in this
endeavor.

We expect to rely on contract manufacturing relationships for lentiviral vectors and for the MB-108 oncolytic virus, as well as for any non-CAR T products that
we  may  in-license  or  acquire  in  the  future  for  co-administration  with  our  CAR  T  products.  However,  there  can  be  no  assurance  that  we  will  be  able  to
successfully contract with such manufacturers on terms acceptable to us, or at all.

Contract manufacturers for these current and potential future non-CAR T products would be subject to ongoing periodic and unannounced inspections by the
FDA, the U.S. Drug Enforcement Administration (“DEA”) and corresponding state agencies to ensure strict compliance with the Current Good Manufacturing
Practice regulations (“cGMP”) and other state and federal regulations. Our contractors, if any, in Europe would face similar challenges from the numerous EU
and  member  state  regulatory  agencies  and  authorized  bodies.  We  do  not  have  control  over  third-party  manufacturers’  compliance  with  these  regulations  and
standards,  other  than  through  contractual  obligations.  If  they  are  deemed  out  of  compliance  with  cGMPs,  product  recalls  could  result,  inventory  could  be
destroyed, production could be stopped, and supplies could be delayed or otherwise disrupted.

If  we  need  to  change  manufacturers  for  these  current  and  potential  future  non-CAR  T  products  after  commercialization,  the  FDA  and  corresponding  foreign
regulatory agencies must approve these new manufacturers in advance, which will involve testing and additional inspections to ensure compliance with FDA
regulations  and  standards  and  may  require  significant  lead  times  and  delay.  Furthermore,  switching  manufacturers  may  be  difficult  because  the  number  of
potential manufacturers is limited. It may be difficult or impossible for us to find a replacement manufacturer quickly or on terms acceptable to us, or at all.

GOVERNMENT AND INDUSTRY REGULATIONS

Numerous  governmental  authorities,  principally  the  FDA  and  corresponding  state  and  foreign  regulatory  agencies,  impose  substantial  regulations  upon  the
clinical development, manufacture and marketing of our product candidates, as well as our ongoing research and development activities. None of our product
candidates has been approved for sale in any market. Before marketing in the U.S., any drug that we develop must undergo rigorous pre-clinical testing and
clinical trials and an extensive regulatory approval process implemented by the FDA under the FDCA. The FDA regulates, among other things, the pre-clinical
and  clinical  testing,  safety,  efficacy,  approval,  manufacturing,  record  keeping,  adverse  event  reporting,  packaging,  labeling,  storage,  advertising,  promotion,
export, and the sale and distribution of biopharmaceutical products.

The regulatory review and approval process is lengthy, expensive and uncertain. We are required to submit extensive preclinical and clinical data and supporting
information to the FDA for each indication or use to establish a product candidate’s safety and efficacy before we can secure FDA approval to market or sell a
product in the U.S. The approval process takes many years, requires the expenditure of substantial resources and may involve ongoing requirements for post-
marketing studies or surveillance. Before commencing clinical trials in humans, we must submit an IND to the FDA containing, among other things, preclinical
data, chemistry, manufacturing and control information, and an investigative plan. Our submission of an IND may not result in FDA authorization to commence
a clinical trial.

The FDA may permit expedited development, evaluation, and marketing of new therapies intended to treat persons with serious or life-threatening conditions for
which  there  is  an  unmet  medical  need  under  its  fast  track  drug  development  program. A  sponsor  can  apply  for  fast  track  designation  initially  at  the  time  of
submission of an IND, or at any time prior to receiving a marketing approval of the new drug application (“NDA”) or biologics license application (“BLA”). To
receive fast track designation, an applicant must demonstrate:

●

●

●

that the therapy is intended to treat a serious or life-threatening condition;

that the therapy is intended to treat a serious aspect of the condition; and

that the therapy has the potential to address unmet medical needs, and this potential is being evaluated in the planned drug development program.

The FDA must respond to a request for fast track designation within 60 calendar days of receipt of the request. Over the course of development, a product in a
fast track development program must continue to meet the criteria for fast track designation. Sponsors of products in fast track drug development programs must
be  in  regular  contact  with  the  reviewing  division  of  the  FDA  to  ensure  that  the  evidence  necessary  to  support  marketing  approval  will  be  developed  and
presented in a format conducive to an efficient review. Sponsors of products in fast track drug development programs ordinarily are eligible for priority review
of a completed application in six months or less and also may be permitted to submit portions of an NDA or BLA to the FDA for review on a rolling basis before
the complete application is submitted.

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In accordance with the FDCA, sponsors of drugs for serious or life-threatening diseases that fill an unmet medical need may seek approval under the FDA’s
accelerated  approval  regulations.  Under  this  authority,  the  FDA  may  grant  marketing  approval  for  a  new  drug  product  on  the  basis  of  adequate  and  well-
controlled clinical trials establishing that the drug product has an effect on a surrogate endpoint that is reasonably likely, based on epidemiologic, therapeutic,
pathophysiologic, or other evidence, to predict clinical benefit or on the basis of an effect on a clinical endpoint other than survival or irreversible morbidity.
Approval will be subject to the requirement that the applicant study the drug further to verify and describe its clinical benefit where there is uncertainty as to the
relation of the surrogate endpoint to clinical benefit or uncertainty as to the relation of the observed clinical benefit to ultimate outcome. Post-marketing studies
are usually underway at the time an applicant files the NDA or BLA. When required to be conducted, such post-marketing studies must also be adequate and
well-controlled. The applicant must carry out any such post-marketing studies with due diligence. Many companies who have been granted the right to utilize an
accelerated approval approach have failed to obtain approval. Moreover, negative or inconclusive results from the clinical trials we hope to conduct or adverse
medical  events  could  cause  us  to  have  to  repeat  or  terminate  the  clinical  trials. Accordingly,  we  may  not  be  able  to  complete  the  clinical  trials  within  an
acceptable time frame, if at all, and, therefore, could not submit the NDA or BLA to the FDA or foreign regulatory authorities for marketing approval.

Clinical testing must meet requirements for institutional review board oversight, informed consent and good clinical practices, and must be conducted pursuant
to an IND, unless exempted.

For purposes of NDA or BLA approval, clinical trials are typically conducted in the following sequential phases:

●

●

●

●

Phase 1: The drug is administered to a small group of humans, either healthy volunteers or patients, for the first time to test for safety, dosage tolerance,
absorption, metabolism, excretion and clinical pharmacology.

Phase 2:  Studies  are  conducted  on  a  larger  number  of  patients  to  assess  the  efficacy  of  the  product,  to  ascertain  dose  tolerance  and  the  optimal  dose
range, and to gather additional data relating to safety and potential adverse events.

Phase 3: Studies establish safety and efficacy in an expanded patient population.

Phase 4: The FDA may request phase 4 post-marketing studies to find out more about the drug’s long-term risks, benefits, and optimal use, or to test the
drug in different patient populations.

The length of time necessary to complete clinical trials varies significantly and may be difficult to predict. Clinical results are frequently susceptible to varying
interpretations that may delay, limit or prevent regulatory approvals. Additional factors that can cause delay or termination of our clinical trials, or that may
increase the costs of these trials, include:

●

●

●

●

●

●

slow patient enrollment due to the nature of the clinical trial plan, the proximity of patients to clinical sites, the eligibility criteria for participation in the
study or other factors;

inadequately trained or insufficient personnel at the study site to assist in overseeing and monitoring clinical trials or delays in approvals from a study
site’s review board;

longer treatment time required to demonstrate efficacy or determine the appropriate product dose;

insufficient supply of the product candidates;

adverse medical events or side effects in treated patients; and

ineffectiveness of the product candidates.

In  addition,  the  FDA,  equivalent  foreign  regulatory  authority,  or  a  data  safety  monitoring  committee  for  a  clinical  trial  may  place  a  clinical  trial  on  hold  or
terminate  it  if  it  concludes  that  subjects  are  being  exposed  to  an  unacceptable  health  risk,  or  for  futility. Any  drug  is  likely  to  produce  some  toxicity  or
undesirable  side  effects  in  animals  and  in  humans  when  administered  at  sufficiently  high  doses  and/or  for  a  sufficiently  long  period  of  time.  Unacceptable
toxicity  or  side  effects  may  occur  at  any  dose  level  at  any  time  in  the  course  of  studies  in  animals  designed  to  identify  unacceptable  effects  of  a  product
candidate, known as toxicological studies, or clinical trials of product candidates. The appearance of any unacceptable toxicity or side effect could cause us or
regulatory authorities to interrupt, limit, delay or abort the development of any of our product candidates and could ultimately prevent approval by the FDA or
foreign regulatory authorities for any or all targeted indications.

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Sponsors of drugs may apply for a special protocol assessment (“SPA”) from the FDA for studies intended to form the primary basis of an efficacy claim. The
SPA process is a procedure by which the FDA provides official evaluation and written guidance on the design and size of proposed protocols that are intended to
form the basis for an NDA or BLA. However, final marketing approval depends on the results of efficacy, the adverse event profile and an evaluation of the
benefit/risk  of  treatment  demonstrated  in  the  pivotal  clinical  trial.  Once  approved,  the  SPA  may  only  be  changed  through  a  written  agreement  between  the
sponsor and the FDA, or in rare cases if the FDA becomes aware of a substantial scientific issue essential to product safety or efficacy the SPA can be rescinded.

Before receiving FDA approval to market a product, we must demonstrate that the product is safe and effective for its intended use by submitting to the FDA an
NDA or BLA containing the preclinical and clinical data that have been accumulated, together with chemistry and manufacturing and controls specifications and
information, and proposed labeling, among other things. The FDA may refuse to accept an NDA or BLA for filing if certain content criteria are not met and,
even after accepting an NDA or BLA, the FDA may require additional information, including clinical data, before approval for marketing a product.

Although uncommon, the FDA may request a Risk Evaluation and Mitigation Strategy, or REMS, as part of an NDA or BLA approval for products with serious
safety concerns to help ensure that the benefits of the product outweigh the risks. The REMS plan contains post-marketing obligations of the sponsor to train
prescribing physicians, monitor off-label drug use, and perhaps the conduct of Phase 4 follow-up studies and registries to ensure the continued safe use of the
drug.

As part of the approval process, the FDA must inspect and approve each manufacturing facility. Among the conditions of approval is the requirement that a
manufacturer’s  quality  control  and  manufacturing  procedures  conform  to  cGMP.  Manufacturers  must  expend  significant  time,  money  and  effort  to  ensure
continued compliance, and the FDA conducts periodic inspections to certify compliance. It may be difficult for our manufacturers or for us to comply with the
applicable cGMP, as interpreted by the FDA, and other FDA regulatory requirements. If we, or our contract manufacturers, fail to comply, then the FDA may
not allow us to market products that have been affected by the failure.

If the FDA grants approval, the approval will be limited to those conditions and patient populations for which the product is safe and effective, as demonstrated
through  clinical  studies  and  as  reflected  in  the  approved  labeling.  Further,  a  product  may  be  marketed  only  in  those  dosage  forms  and  for  those  indications
approved in the NDA or BLA. Certain changes to an approved NDA or BLA, including, with certain exceptions, any significant changes to labeling, may require
prior approval of a supplemental application before the drug may be marketed as changed. Any products that we manufacture or distribute pursuant to FDA
approvals are subject to continuing monitoring and regulation by the FDA, including compliance with cGMP and the reporting of adverse experiences with the
drugs. The nature of marketing claims that the FDA will permit us to make in the labeling and advertising of our products will generally be limited to those
specified in FDA approved labeling, and the advertising of our products will be subject to comprehensive monitoring and regulation by the FDA. Drugs whose
review was accelerated may carry additional restrictions on marketing activities, including the requirement that all promotional materials are pre-submitted to the
FDA. Claims exceeding those contained in the approved labeling will constitute a violation of the FDCA. Violations of the FDCA or regulatory requirements at
any  time  during  the  product  development  process,  approval  process,  or  marketing  and  sale  following  approval  may  result  in  agency  enforcement  actions,
including  withdrawal  of  approval,  recall,  seizure  of  products,  warning  letters,  injunctions,  fines  and/or  civil  or  criminal  penalties. Any  agency  enforcement
action could have a material adverse effect on our business.

Failure  to  comply  with  applicable  federal,  state  and  foreign  laws  and  regulations  would  likely  have  a  material  adverse  effect  on  our  business.  In  addition,
federal, state and foreign laws and regulations regarding the manufacture and sale of new drugs are subject to future changes.

Other Healthcare Laws and Compliance Requirements

In the U.S., our activities are potentially subject to regulation by various federal, state and local authorities in addition to the FDA, including the Centers for
Medicare and Medicaid Services (formerly the Health Care Financing Administration), other divisions of the United States Department of Health and Human
Services (e.g., the Office of Inspector General), the United States Department of Justice and individual United States Attorney offices within the Department of
Justice, and state and local governments.

Pharmaceutical Coverage, Pricing and Reimbursement

In  the  U.S.  and  markets  in  other  countries,  sales  of  any  products  for  which  we  receive  regulatory  approval  for  commercial  sale  will  depend  in  part  on  the
availability of reimbursement from third-party payors, including government health administrative authorities, managed care providers, private health insurers
and  other  organizations.  Third-party  payors  are  increasingly  examining  the  medical  necessity  and  cost-effectiveness  of  medical  products  and  services,  in
addition to their safety and efficacy, and, accordingly, significant uncertainty exists as to the reimbursement status of newly approved therapeutics. Adequate
third-party reimbursement may not be available for our products to

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enable us to realize an appropriate return on our investment in research and product development. We are unable to predict the future course of federal or state
health care legislation and regulations, including regulations that will be issued to implement provisions of the health care reform legislation enacted in 2010,
known as the Affordable Care Act. The Affordable Care Act and further changes in the law or regulatory framework could have a material adverse effect on our
business.

International Regulation

In addition to regulations in the U.S., there are a variety of foreign regulations governing clinical trials and commercial sales and distribution of our product
candidates. The approval process varies from country to country, and the time may be longer or shorter than that required for FDA approval.

Item 1A.

Risk Factors

Investing  in  our  Common  Stock  or  any  other  type  of  equity  or  debt  securities  we  may  offer  (together,  our  “Securities”)  involves  a  high  degree  of  risk.  The
following information sets forth risk factors that could cause our actual results to differ materially from those contained in forward-looking statements we have
made in this Form 10-K and those we may make from time to time. You should carefully consider the risks described below, in addition to the other information
contained in this Form 10-K, before making an investment decision. Our business, financial condition or results of operations could be harmed by any of these
risks. The risks and uncertainties described below are not the only ones we face. Additional risks not presently known to us, or other factors not perceived by us
to present significant risks to our business at this time also may impair our business operations.

Risks Related to Our Finances and Capital Requirements

We have incurred significant losses since our inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.
We  do  not  have  any  products  that  are  approved  for  commercial  sale  and  therefore  do  not  expect  to  generate  any  revenues  from  product  sales  in  the
foreseeable future, if ever.

We have a limited operating history. We have focused primarily on in-licensing and developing our product candidates, with the goal of supporting regulatory
approval  for  these  product  candidates.  We  have  incurred  losses  since  our  inception  in  March  2015  and  have  an  accumulated  deficit  of  $329.4  million  as  of
December  31,  2022.  We  expect  to  continue  to  incur  significant  operating  losses  for  the  foreseeable  future.  We  also  do  not  anticipate  that  we  will  achieve
profitability for a period of time after generating material revenues, if ever. If we are unable to generate revenues, we will not become profitable and may be
unable to continue operations without continued funding.

Because of the numerous risks and uncertainties associated with developing pharmaceutical products, we are unable to predict the timing or amount of increased
expenses or when or if we will be able to achieve profitability. Our net losses may fluctuate significantly from quarter to quarter and year to year. We anticipate
that our expenses will increase substantially if:

●

one  or  more  of  our  product  candidates  receive  regulatory  approval  and  are  approved  for  commercial  sale,  due  to  our  need  to  establish  the  necessary
commercial infrastructure to launch and commercialize this product candidate without substantial delays, including hiring sales and marketing personnel
and contracting with third parties for manufacturing, testing, warehousing, distribution, cash collection and related commercial activities;

● we are required by the FDA or foreign regulatory authorities to perform studies in addition to those currently expected;

●

there are any delays in completing our clinical trials or the development of any of our product candidates;

● we execute other collaborative, licensing or similar arrangements that require us to make payments to collaborators or licensors;

●

●

●

there are variations in the level of expenses related to our future development programs;

there are any product liability or intellectual property infringement lawsuits in which we may become involved; and

there are any regulatory developments affecting product candidates of our competitors.

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Our  ability  to  become  profitable  depends  upon  our  ability  to  generate  revenue.  To  date,  we  have  not  generated  any  revenue  from  our  development  stage
products, and we do not know when, or if, we will generate any revenue. Our ability to generate revenue depends on a number of factors, including, but not
limited to, our ability to:

●

obtain regulatory approval for one or more of our product candidates, or any future product candidate that we may license or acquire;

● manufacture  or  have  manufactured  commercial  quantities  of  one  or  more  of  our  product  candidates  or  any  future  product  candidate,  if  approved,  at

acceptable cost levels; and

●

develop a commercial organization and the supporting infrastructure required to successfully market and sell one or more of our product candidates or
any future product candidate, if approved.

Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain
profitable would depress the value of the Company and could impair our ability to raise capital, expand our business, maintain our research and development
efforts, diversify our product offerings or even continue our operations. A decline in the value of the Company could also cause you to lose all or part of your
investment.

There is substantial doubt regarding our ability to continue as a going concern. We will need to raise additional funding, which may not be available on
acceptable  terms  to  the  Company,  or  at  all.  Failure  to  obtain  this  necessary  capital  when  needed  may  force  us  to  delay,  limit  or  terminate  our  product
development efforts or other operations.

We  are  currently  advancing  our  programs  in  hematologic  cancers,  solid  tumors  and  rare  genetic  diseases  through  clinical  development.  Developing  and
commercializing CAR T and gene therapy products is expensive, and we do not expect to generate meaningful product revenues in the foreseeable future until we
obtain marketing approval for products in the United States and following any potential commercial launch.

As of December 31, 2022, our cash and cash equivalents were $75.7 million. Based on our current business plan, there is substantial doubt regarding our
ability to continue as a going concern for a period of one year after the date that our financial statements for the year ended December 31, 2022 are issued. Our
fundraising efforts to raise additional funding may divert our management from their day-to-day activities, which may adversely affect our ability to develop and
commercialize our potential products following marketing approval if and when obtained. In addition, we cannot guarantee that financing will be available in
sufficient amounts or on terms acceptable to us, if at all. Moreover, the terms of any financing may adversely affect the holdings or the rights of our stockholders
and the issuance of additional securities, whether equity or debt, by us, or the possibility of such issuance, may cause the market price of our shares to decline.
The sale of additional equity or convertible securities would dilute all of our stockholders. Our current and the potential for additional indebtedness would result
in increased fixed payment obligations, and we may be required to agree to certain restrictive covenants, such as limitations on our ability to incur additional
debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to
conduct our business. We could also be required to seek funds through arrangements with collaborative partners or otherwise at an earlier stage than otherwise
would be desirable and we may be required to relinquish rights to some of our technologies or product candidates or otherwise agree to terms unfavorable to us,
any of which may have a material adverse effect on our business, operating results and prospects.

If  we  are  unable  to  obtain  funding  on  a  timely  basis,  we  may  be  required  to  further  revise  our  business  plan  and  strategy,  which  may  result  in  us  (i)
significantly curtailing, delaying or discontinuing one or more of our research or development programs or the commercialization of any product candidates, (ii)
selling certain of our assets (which could include our manufacturing facility) and/or (iii) may result in our being unable to expand our operations or otherwise
capitalize on our business opportunities. As a result, our business, financial condition, and results of operations could be materially affected.

We are exposed to interest rate risk under our Term Loan with Runway, which could cause our debt service obligations to increase
significantly.

We are exposed to market risk from changes in interest rates. Our Term Loan with Runway bears a variable interest rate equal to the (i) 8.75% and (ii) the greater
of (A) the prime rate last quoted in The Wall Street Journal (or a comparable replacement rate if The Wall Street Journal ceases to quote such rate) and (B)
0.50%. The Federal Reserve has recently raised, and may in the future further raise, interest rates to combat the effects of recent high inflation. An increase in
interest rates by the Federal Reserve has and could in the future cause the prime rate to increase, which has and could in the future increase our debt service
obligations. Significant increases in such obligations could have a negative impact on our financial position or operating results, including cash available for
servicing our indebtedness, or result in increased borrowing costs in the future.

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Our short operating history makes it difficult to evaluate our business and prospects.

We have only been conducting operations since our incorporation in March 2015. Our operations to date have been limited to preclinical operations and the in-
licensing of our product candidates. We have not yet demonstrated an ability to successfully complete clinical trials, obtain regulatory approvals, manufacture a
clinical scale or commercial scale product, or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful
product  commercialization.  Consequently,  any  predictions  about  our  future  performance  may  not  be  as  accurate  as  they  could  be  if  we  had  a  history  of
successfully developing and commercializing pharmaceutical products.

In addition, as a young business, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors. We will need
to expand our capabilities to support commercial activities. We may not be successful in adding such capabilities.

We expect our financial condition and operating results to continue to fluctuate significantly from quarter to quarter and year to year due to a variety of factors,
many  of  which  are  beyond  our  control. Accordingly,  you  should  not  rely  upon  the  results  of  any  past  quarterly  period  as  an  indication  of  future  operating
performance.

Our  loan  agreement  requires  us  to  meet  certain  funding  conditions  and  operating  conditions  which  place  restrictions  on  our  operating  and  financial
flexibility.

Our  Term  Loan  with  Runway,  which  we  entered  into  in  March  2022,  contains  a  variety  of  affirmative  and  negative  covenants,  including  required  financial
reporting, limitations on certain dispositions of assets, limitations on the incurrence of additional debt, limitations on the ability to pay cash dividends and other
requirements. The Term Loan also subjects us to financial covenants in respect of minimum liquidity, pursuant to which we must maintain an unrestricted cash
balance in an amount equal to or greater than the trailing five months of our operating cash flow. This covenant imposes significant operational constraints on us,
and it will be difficult for us to continue to comply with the covenant absent remedial measures to reduce costs and/or raise additional capital. The Term Loan
contains  customary  events  of  default,  which  include  among  others,  non-payment  of  principal,  violation  of  covenants,  inaccuracy  of  representations  and
warranties,  insolvency  events,  materials  judgments,  and  certain  regulatory-related  events.  These  restrictions  may  adversely  affect  our  ability  to  operate  our
business, finance our operations, engage in business activities or fully pursue our business strategies. To secure our performance of our obligations under this
Term Loan, we granted a security interest in substantially all of our assets, other than certain intellectual property assets and certain other excluded collateral, to
Runway. Our failure to comply with the covenants in the Term Loan, the occurrence of a material impairment in our prospect of repayment or in the perfection or
priority of Runway’s lien on our assets, as determined by Runway, or the occurrence of certain other specified events could result in an event of default that, if
not cured or waived, could result in the acceleration of all or a substantial portion of our debt, potential foreclosure on our assets and other adverse results. In the
event  of  an  acceleration  of  amounts  due  under  the  Term  Loan  as  a  result  of  an  event  of  default,  we  may  not  have  enough  available  cash  or  be  able  to  raise
additional funds through equity or debt financing to repay such indebtedness.

Additionally,  we  are  bound  by  certain  negative  covenants  setting  forth  actions  that  are  not  permitted  to  be  taken  during  the  term  of  the  Term  Loan  without
consent  of  Runway,  including,  without  limitation,  incurring  certain  additional  indebtedness,  making  certain  asset  dispositions,  entering  into  certain  mergers,
acquisitions or other business combination transactions or incurring any non-permitted lien or other encumbrance on our assets. The foregoing prohibitions and
constraints on our operations could result in our inability to: (i) acquire promising intellectual property or other assets on desired timelines or terms; (ii) reduce
costs by disposing of assets or business segments no longer deemed advantageous to retain; (iii) stimulate further corporate growth or development through the
assumption of additional debt; or (iv) enter into other arrangements that necessitate the imposition of a lien on corporate assets.

We will require substantial additional funding which may not be available to us on acceptable terms, or at all. If we fail to raise the necessary additional
capital, we may be unable to complete the development and commercialization of our product candidates or continue our development programs.

Our operations have consumed substantial amounts of cash since inception. We will need to significantly increase our spending to advance the preclinical and
clinical development of our product candidates and launch and commercialize any product candidates for which we may receive regulatory approval, including
building  our  own  commercial  organizations  to  address  certain  markets.  We  will  require  additional  capital  for  the  further  development  and,  if  approved,
commercialization of our product candidates, as well as to fund our other operating expenses and capital expenditures. As of December 31, 2022, we had $76.7
million in cash and restricted cash. We cannot provide any assurance that we will be able to raise funds to complete the development of our product candidates.
Additionally, if we are unable to secure additional funding, it is likely that we will need to delay or terminate the development of certain product candidates; any
such delay or

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termination, or the announcement of any such delay or termination, may impact our potential growth and have a material adverse effect on the value of our debt
and equity securities.

We cannot be certain that additional funding will be available on acceptable terms, or at all. Additional funding may be more difficult to obtain, or may be more
expensive, as a result of recent increases in inflation and interest rates in the U.S. economy generally. If we are unable to raise additional capital in sufficient
amounts or on terms acceptable to us, we may have to significantly delay, scale back or discontinue the development or, if approved, commercialization of one
or more of our product candidates. We may also seek collaborators for one or more of our current or future product candidates at an earlier stage than otherwise
would be desirable or on terms that are less favorable than might otherwise be available. Any of these events could significantly harm our business, financial
condition and prospects.

Our future funding requirements will depend on many factors, including, but not limited to:

●

●

●

●

●

●

●

●

●

the timing, design and conduct of, and results from, preclinical studies and clinical trials for our product candidates;

the potential for delays in our efforts to seek regulatory approval for our product candidates, and any costs associated with such delays;

the costs of establishing a commercial organization to sell, market and distribute our product candidates;

the rate of progress and costs of our efforts to prepare for the submission of an NDA or BLA for any product candidates that we may in-license or acquire
in the future, and the potential that we may need to conduct additional clinical trials to support applications for regulatory approval;

the costs of filing, prosecuting, defending and enforcing any patent claims and other intellectual property rights associated with our product candidates,
including any such costs we may be required to expend if our licensors are unwilling or unable to do so;

the cost and timing of securing sufficient supplies of our product candidates from  our  contract  manufacturers  for  clinical  trials  and  in  preparation  for
commercialization;

the effect of competing technological and market developments;

the terms and timing of any collaborative, licensing, co-promotion or other arrangements that we may establish;

if one or more of our product candidates are approved, the potential that we may be required to file a lawsuit to defend our patent rights or regulatory
exclusivities from challenges by companies seeking to market generic versions of one or more of our product candidates; and

●

the success of the commercialization of one or more of our product candidates, if approved.

Future capital requirements will also depend on the extent to which we acquire or invest in additional complementary businesses, products and technologies,
although we currently have no commitments or agreements relating to any of these types of transactions.

In order to carry out our business plan and implement our strategy, we anticipate that we will need to obtain additional financing from time to time and may
choose to raise additional funds through strategic collaborations, licensing arrangements, public or private equity or debt financing, bank lines of credit, asset
sales, government grants, or other arrangements. We cannot be sure that any additional funding, if needed, will be available on terms favorable to us or at all.
Furthermore, any additional equity or equity-related financing may be dilutive to our stockholders, and debt or equity financing, if available, may subject us to
restrictive  covenants  and  significant  interest  costs.  If  we  obtain  funding  through  a  strategic  collaboration  or  licensing  arrangement,  we  may  be  required  to
relinquish our rights to certain of our product candidates or marketing territories.

Our inability to raise capital when needed would harm our business, financial condition and results of operations, and could cause our stock value to decline or
require that we wind down our operations altogether.

Under current SEC regulations, if at the time we file our Annual Report on Form 10-K our public float is less than $75 million, and for so long as our public
float remains less than $75 million, the amount we can raise through primary public offerings of securities in any twelve-month period using shelf registration
statements is limited to an aggregate of one-third of our public float, which is referred to as the “baby shelf rules.” SEC regulations permit us to use the highest
closing sales price of our common stock (or the average of the last bid and last ask prices of our common stock) on any day within 60 days of sales under the
registration statement to calculate our public float.

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As of the date of this Annual Report on Form 10-K, our public float was less than $75 million. As a result, for sales following the date of this Annual Report on
Form 10-K, and until we again have a public float with a value in exceeds of $75 million, if ever, we only have the capacity to sell shares up to one-third of our
public float under shelf registration statements in any twelve-month period. If our public float decreases, the amount of securities we may sell under our Form S-
3 shelf registration statements will also decrease.

Raising additional capital, including through lending arrangements, may cause dilution to our existing stockholders, restrict our operations or require us to
relinquish proprietary rights.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our cash needs through a combination of equity offerings, debt
financings, grants and license and development agreements in connection with any collaborations. To the extent that we raise additional capital through the sale
of equity or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences
that  adversely  affect  your  rights  as  a  stockholder.  Debt  financing,  including  through  lending  arrangements,  and  preferred  equity  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 additional funds through collaborations, strategic alliances or marketing, distribution 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  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 product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop
and market ourselves.

We  will  continue  to  incur  significant  increased  costs  as  a  result  of  operating  as  a  public  company,  and  our  management  will  be  required  to  devote
substantial time to new compliance initiatives.

As a public company, we incur significant legal, accounting and other expenses under the Sarbanes-Oxley Act of 2002, or the Sarbanes-Oxley Act, as well as
rules  subsequently  implemented  by  the  SEC,  and  the  rules  of  the  Nasdaq  Stock  Exchange.  These  rules  impose  various  requirements  on  public  companies,
including  requiring  establishment  and  maintenance  of  effective  disclosure  and  financial  controls  and  appropriate  corporate  governance  practices.  Our
management  and  other  personnel  have  devoted  and  will  continue  to  devote  a  substantial  amount  of  time  to  these  compliance  initiatives.  Moreover,  these
rules and regulations increase our legal and financial compliance costs and make some activities more time-consuming and costly. For example, these rules and
regulations make it more difficult and more expensive for us to obtain director and officer liability insurance, and we may be required to accept reduced policy
limits and coverage or incur substantially higher costs to obtain the same or similar coverage. As a result, it may be more difficult for us to attract and retain
qualified persons to serve on our board of directors, our board committees or as executive officers.

The Sarbanes-Oxley Act requires, among other things, that we maintain effective internal controls for financial reporting and disclosure controls and procedures.
As  a  result,  we  are  required  to  periodically  perform  an  evaluation  of  our  internal  controls  over  financial  reporting  to  allow  management  to  report  on  the
effectiveness of those controls, as required by Section 404 of the Sarbanes-Oxley Act. These efforts to comply with Section 404 and related regulations have
required, and continue to require, the commitment of significant financial and managerial resources. While we anticipate maintaining the integrity of our internal
controls  over  financial  reporting  and  all  other  aspects  of  Section  404,  we  cannot  be  certain  that  a  material  weakness  will  not  be  identified  when  we  test  the
effectiveness of our control systems in the future. If a material weakness is identified, we could be subject to sanctions or investigations by the SEC or other
regulatory  authorities,  which  would  require  additional  financial  and  management  resources,  costly  litigation  or  a  loss  of  public  confidence  in  our  internal
controls, which could have an adverse effect on the market price of our stock.

Compliance with the Sarbanes-Oxley Act will require substantial financial and management resources and may increase the time and costs of completing an
acquisition.

A business that we identify as a potential acquisition target may not be in compliance with the provisions of the Sarbanes-Oxley Act regarding the adequacy of
internal controls. The development of the internal controls of any such entity to achieve compliance with the Sarbanes-Oxley Act may increase the time and costs
necessary  to  complete  any  such  acquisition.  Furthermore,  any  failure  to  implement  required  new  or  improved  controls,  or  difficulties  encountered  in  the
implementation of adequate controls over our financial processes and reporting in the future, could harm our operating results or cause us to fail to meet our
reporting obligations. Inferior internal controls could also cause investors to lose confidence in our reported financial information, which could have a negative
effect on the trading price of our securities.

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Our ability to use our pre-change NOLs and other pre-change tax attributes to offset post-change taxable income or taxes may be subject to limitation.

We may, from time to time, carry net operating loss carryforwards (“NOLs”) as deferred tax assets on our balance sheet. Under Sections 382 and 383 of the
Internal  Revenue  Code  of  1986,  as  amended,  if  a  corporation  undergoes  an  “ownership  change”  (generally  defined  as  a  greater  than  50-percentage-  point
cumulative change (by value) in the equity ownership of certain stockholders over a rolling three-year period), the corporation’s ability to use its pre-change
NOLs and other pre-change tax attributes to offset its post-change taxable income or taxes may be limited. We may experience ownership changes in the future
as a result of shifts in our stock ownership, some of which changes are outside our control. As a result, our ability to use our pre-change NOLs and other pre-
change tax attributes to offset post-change taxable income or taxes may be subject to limitation.

Risks Related to Our Business Strategy, Structure, and Organization

We currently have no products for sale. We are heavily dependent on the success of our product candidates, and we cannot give any assurances that any of
our product candidates will receive regulatory approval or be successfully commercialized.

To date, we have invested a significant portion of our efforts and financial resources in the acquisition and development of our product candidates. We have not
demonstrated our ability to perform the functions necessary for the successful acquisition, development or commercialization of the technologies we are seeking
to develop. As an early stage company, we have limited experience and have not yet demonstrated an ability to successfully overcome many of the risks and
uncertainties  frequently  encountered  by  companies  in  new  and  rapidly  evolving  fields,  particularly  in  the  biopharmaceutical  area.  Our  future  success  is
substantially  dependent  on  our  ability  to  successfully  develop,  obtain  regulatory  approval  for,  and  then  commercialize  such  product  candidates.  Most  of  our
product candidates are currently in early stage clinical trials. Our business depends entirely on the successful development and commercialization of our product
candidates, which may never occur. We currently have no drug products for sale, currently generate no revenues from sales of any drug products, and may never
be able to develop or commercialize a marketable product.

The  successful  development,  and  any  commercialization,  of  our  technologies  and  any  product  candidates  that  may  occur  would  require  us  to  successfully
perform a variety of functions, including:

●

●

●

●

●

●

●

developing our technology platform;

identifying, developing, formulating, manufacturing and commercializing product candidates;

entering into successful licensing and other arrangements with product development partners;

participating in regulatory approval processes, including ultimately gaining approval to market a drug product, which may not occur;

obtaining  sufficient  quantities  of  our  product  candidates  from  our  third-party  manufacturers  to  meet  clinical  trial  needs  and,  if  approved,  to  meet
commercial demand at launch and thereafter;

establishing and maintaining agreements with wholesalers, distributors and group purchasing organizations on commercially reasonable terms;

conducting sales and marketing activities including hiring, training, deploying and supporting our sales force and creating market demand for our product
candidates through our own marketing and sales activities, and any other arrangements to promote our product candidates that we may establish; and

● maintaining patent protection and regulatory exclusivity for our product candidates.

Our  operations  have  been  limited  to  organizing  the  Company,  acquiring,  developing  and  securing  our  proprietary  technology  and  identifying  and  obtaining
preclinical data or clinical data for various product candidates. These operations provide a limited basis for you to assess our ability to continue to develop our
technology,  identify  product  candidates,  develop  and  commercialize  any  product  candidates  we  are  able  to  identify  and  enter  into  successful  collaborative
arrangements with other companies, as well as for you to assess the advisability of investing in our securities. Each of these requirements will require substantial
time, effort and financial resources.

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Each  of  our  product  candidates  will  require  additional  clinical  development,  management  of  clinical  and  manufacturing  activities,  regulatory  approval  in  the
jurisdictions  in  which  we  plan  to  market  the  product,  obtaining  manufacturing  supply,  building  a  commercial  organization,  and  significant  marketing  efforts
before we generate any revenues from product sales, which may not occur. We are not permitted to market or promote any of our product candidates in the U.S.
or  any  other  jurisdiction  before  we  receive  regulatory  approval  from  the  FDA  or  comparable  foreign  regulatory  authority,  respectively,  and  we  may  never
receive such regulatory approval for any of our product candidates.

Our future growth depends in part on our ability to identify and acquire or in-license products, and if we do not successfully identify and acquire or in-
license related product candidates or integrate them into our operations, we may have limited growth opportunities.

An  important  part  of  our  business  strategy  is  to  continue  to  develop  a  pipeline  of  product  candidates  by  acquiring  or  in-licensing  products,  businesses  or
technologies that we believe are a strategic fit with our focus on ex vivo lentiviral gene therapy for rare genetic diseases and on novel combinations of CAR T
cells with immuno-oncology antibodies, other biologics, and small molecule kinase inhibitors. Future in-licenses or acquisitions, however, may entail numerous
operational and financial risks, including, but not necessarily limited to:

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exposure to unknown liabilities;

disruption of our business and diversion of our management’s time and attention to develop acquired products or technologies;

difficulty  or  inability  to  secure  financing  to  fund  development  activities  for  such  acquired  or  in-licensed  technologies  in  the  current  economic
environment;

incurrence of substantial debt or dilutive issuances of securities to pay for acquisitions;

higher than expected acquisition and integration costs;

increased amortization expenses;

difficulty and cost in combining the operations and personnel of any acquired businesses with our operations and personnel;

impairment of relationships with key suppliers or customers of any acquired businesses due to changes in management and ownership; and

inability to retain key employees of any acquired businesses.

We have limited resources to identify and execute the acquisition or in-licensing of third-party products, businesses and technologies and integrate them into our
current infrastructure. In particular, we may compete with larger pharmaceutical companies and other competitors in our efforts to establish new collaborations
and  in-licensing  opportunities.  These  competitors  may  have  access  to  greater  financial  resources  than  us  and  may  have  greater  expertise  in  identifying  and
evaluating new opportunities. Moreover, we may devote resources to potential acquisitions or in-licensing opportunities that are never completed, or we may fail
to realize the anticipated benefits of such efforts.

Our approach to the development of our product candidates is unproven, and we do not know whether we will be able to develop any products of commercial
value.

Our products candidates are emerging technologies and, consequently, it is conceivable that such technologies may ultimately fail to develop into commercially
viable therapies to treat human patients with cancer or other diseases. One of the reasons for the lack of commercial viability could be our inability to obtain
regulatory approval for such technologies.

CAR T is a new approach to cancer treatment that presents significant challenges.

We  have  concentrated  much  of  our  research  and  development  efforts  on  CAR  T  technology,  and  our  future  success  is  highly  dependent  on  the  successful
development of T cell immunotherapies in general and our CAR T technology and product candidates in particular. Because CAR T is a new approach to cancer
immunotherapy and cancer treatment generally, developing and commercializing our product candidates subjects us to a number of challenges, including, but
not necessarily limited to:

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obtaining regulatory approval from the FDA and other regulatory authorities that may have very limited experience with the commercial development of
genetically modified T cell therapies for cancer;

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developing and deploying consistent and reliable processes for engineering a patient’s T cells ex vivo and infusing the engineered T cells back into the
patient;

conditioning patients with chemotherapy in conjunction with delivering each of our products, which may increase the risk of adverse side effects of our
products;

educating medical personnel regarding the potential side effect profile of each of our products;

developing processes for the safe administration of these products, including long-term follow-up for all patients who receive our product candidates;

sourcing clinical and, if approved, commercial supplies for the materials used to manufacture and process our product candidates;

developing a manufacturing process and distribution network with a cost of goods that allows for an attractive return on investment;

establishing  sales  and  marketing  capabilities  after  obtaining  any  regulatory  approval  to  gain  market  acceptance,  and  obtaining  adequate  coverage,
reimbursement and pricing by third-party payors and government authorities; and

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developing therapies for types of cancers beyond those addressed by our current product candidates.

We may expend our limited resources to pursue a particular product candidate or indication and fail to capitalize on product candidates or indications 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 research programs and product candidates that we identify for specific indications. As
a result, we may forego or delay the pursuit of opportunities with other product candidates or for other indications 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. Our spending on
current and future research and development programs and product candidates for specific indications may not yield any commercially viable products. If we do
not accurately and/or effectively 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.

We are a "smaller reporting company," and the reduced disclosure requirements applicable to smaller reporting companies may make our common stock
less attractive to investors.

We are a smaller reporting company, and we will remain a smaller reporting company until the fiscal year following the determination that our voting and non-
voting common shares held by non-affiliates is more than $250 million measured on the last business day of our second fiscal quarter, or our annual revenues are
more than $100 million during the most recently completed fiscal year and our voting and non-voting common shares held by non-affiliates is more than $700
million  measured  on  the  last  business  day  of  our  second  fiscal  quarter.  Smaller  reporting  companies  are  able  to  provide  simplified  executive  compensation
disclosure, are exempt from the auditor attestation requirements of Section 404, and have certain other reduced disclosure obligations, including, among other
things, being required to provide only two years of audited financial statements and not being required to provide selected financial data, supplemental financial
information or risk factors.

We have elected to take advantage of certain of the reduced reporting obligations available to us. We cannot predict whether investors will find our common
stock less attractive if we rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market
for our common stock and our stock price may be reduced or more volatile.

Risks Inherent in Drug Development and Commercialization

Delays in the commencement or conduct of our clinical trials could result in increased costs and delay our ability to pursue regulatory approval.

The commencement or conduct of clinical trials can be delayed for a variety of reasons, including, but not necessarily limited to, delays in:

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obtaining regulatory approval to commence a clinical trial;

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identifying, recruiting and training suitable clinical investigators;

reaching and preserving agreements on acceptable terms with prospective clinical research organizations (“CROs”) and trial sites, the terms of which can
be subject to extensive negotiation, may be subject to modification from time to time and may vary significantly among different CROs and trial sites;

obtaining sufficient quantities of a product candidate for use in clinical trials;

obtaining Institutional Review Board (“IRB”) or ethics committee approval to conduct a clinical trial at a prospective site;

developing and validating companion diagnostics on a timely basis, if required;

adding new clinical sites once a trial has begun;

change in the principal investigator or other key staff overseeing the clinical trial at a given site;

identifying, recruiting and enrolling patients to participate in a clinical trial; or

retaining (or replacing) patients who have initiated a clinical trial but who may withdraw due to adverse events from the therapy, insufficient efficacy,
fatigue with the clinical trial process, personal issues, or other reasons.

Any delays in the commencement of our clinical trials will delay our ability to pursue regulatory approval for product candidates. In addition, many of the factors
that cause, or lead to, a delay in the commencement of clinical trials may also ultimately lead to the denial of regulatory approval of a product candidate.

Suspensions or delays in the completion of clinical testing could result in increased costs and delay or prevent our ability to complete development of that
product or generate product revenues.

Once a clinical trial has begun, patient recruitment and enrollment may be slower than we anticipate due to the nature of the clinical trial plan, the proximity of
patients  to  clinical  sites,  the  eligibility  criteria  for  participation  in  the  study  or  other  factors.  Clinical  trials  may  also  be  delayed  as  a  result  of  ambiguous  or
negative  interim  results  or  difficulties  in  obtaining  sufficient  quantities  of  product  manufactured  in  accordance  with  regulatory  requirements  and  on  a  timely
basis. Further, a clinical trial may be modified, suspended or terminated by us, an IRB, an ethics committee or a data safety monitoring committee overseeing
the  clinical  trial,  any  clinical  trial  site  with  respect  to  that  site,  or  the  FDA  or  other  regulatory  authorities,  due  to  a  number  of  factors,  including,  but  not
necessarily limited to:

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failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols;

inspection of the clinical trial operations or clinical trial site by the FDA or other regulatory authorities resulting in the imposition of a clinical hold;

stopping rules contained in the protocol;

unforeseen safety issues or any determination that the clinical trial presents unacceptable health risks; and

lack of adequate funding to continue the clinical trial.

Changes in regulatory requirements and guidance also may occur, and we may need to amend clinical trial protocols to reflect these changes. Amendments may
require us to resubmit clinical trial protocols to IRBs for re-examination, which may in turn impact the costs and timing of, and the likelihood of successfully
completing, a clinical trial. If we experience delays in the completion of, or if we must suspend or terminate, any clinical trial of any product candidate, our
ability to obtain regulatory approval for that product candidate will be delayed, and the commercial prospects, if any, for the product candidate may suffer as a
result. In addition, many of these factors may also ultimately lead to the denial of regulatory approval of a product candidate.

Product candidates that we advance into clinical trials may not receive regulatory approval.

Pharmaceutical development has inherent risks. We will be required to demonstrate through well-controlled clinical trials that product candidates are effective
with a favorable benefit-risk profile for use in their target indications before seeking regulatory approvals for their

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commercial sale. Success in early clinical trials does not mean that later clinical trials will be successful, as product candidates in later-stage clinical trials may
fail to demonstrate sufficient safety or efficacy despite having progressed through initial clinical testing. Also, we may need to conduct additional clinical trials
that  are  not  currently  anticipated.  Companies  frequently  suffer  significant  setbacks  in  advanced  clinical  trials,  even  after  earlier  clinical  trials  have  shown
promising results. As a result, product candidates that we advance into clinical trials may not receive regulatory approval.

In  addition,  even  if  our  product  candidates  were  to  obtain  approval,  regulatory  authorities  may  approve  any  such  product  candidates  or  any  future  product
candidate for fewer or more limited indications than we request, may not approve the price we intend to charge for our products, may grant approval contingent
on the performance of costly post-marketing clinical trials, or may approve a product candidate with a label that does not include the labeling claims necessary
or  desirable  for  the  successful  commercialization  of  that  product  candidate.  The  regulatory  authority  may  also  require  the  label  to  contain  warnings,
contraindications, or precautions that limit the commercialization of the product. In addition, the DEA (or foreign equivalent) may classify one or more of our
product candidates in scheduling under the Controlled Substances Act (or its foreign equivalent) that could impede such product’s commercial viability. Any of
these scenarios could impact the commercial prospects for one or more of our current or future product candidates.

Any  product  candidates  we  advance  into  clinical  development  are  subject  to  extensive  regulation,  which  can  be  costly  and  time  consuming,  cause
unanticipated delays or prevent the receipt of the required approvals to commercialize product candidates.

The  research  and  clinical  development,  testing,  manufacturing,  labeling,  storage,  record-keeping,  advertising,  promotion,  import,  export,  marketing  and
distribution of any product candidate, including our product candidates, is subject to extensive regulation by the FDA in the United States and by comparable
health authorities in foreign markets. In the United States, we are not permitted to market a product candidate until such product candidate’s BLA or NDA is
approved by the FDA. The process of obtaining approval is uncertain, expensive, often spanning many years, and can vary substantially based upon the type,
complexity and novelty of the products involved. In addition to significant and expensive clinical testing requirements, our ability to obtain marketing approval
for product candidates depends on obtaining the final results of required non-clinical testing, including characterization of the manufactured components of our
product  candidates  and  validation  of  our  manufacturing  processes.  The  FDA  may  determine  that  our  product  manufacturing  processes,  testing  procedures  or
equipment  and  facilities  are  inadequate  to  support  approval.  Approval  policies  or  regulations  may  change,  and  the  FDA  has  substantial  discretion  in  the
pharmaceutical approval process, including the ability to delay, limit or deny approval of a product candidate for many reasons. Despite the time and expense
invested in the clinical development of product candidates, regulatory approval is never guaranteed.

The FDA and other regulatory agencies can delay, limit or deny approval of a product candidate for many reasons, including, but not limited to:

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the FDA or comparable foreign regulatory authorities may disagree with the trial design or implementation of our clinical trials, including proper use of
clinical trial methods and methods of data analysis;

an inability to establish sufficient data and information to demonstrate to the satisfaction of the FDA that a product candidate is safe and effective for an
indication;

the FDA may not accept clinical data from trials conducted by individual investigators or in countries where the standard of care is potentially different
from that of the United States;

the results of clinical trials may not meet the level of statistical significance required by the FDA for approval;

the FDA may disagree with the interpretation of data from preclinical studies or clinical trials;

the  FDA  may  determine  that  our  manufacturing  processes  or  facilities  or  those  of  third-party  manufacturers  with  which  we  or  our  respective
collaborators currently contract for clinical supplies and plan to contract for commercial supplies do not satisfactorily comply with CGMPs; or

the approval policies or interpretation of regulations of the FDA may significantly change in a manner rendering the clinical data insufficient for approval
or the product characteristics or benefit-risk profile unfavorable for approval.

With respect to foreign markets, approval procedures vary among countries and, in addition to the aforementioned risks, can involve additional product testing,
administrative review periods and agreements with pricing authorities. In addition, rapid drug and biological development during the COVID-19 pandemic has
raised questions about the safety and efficacy of certain marketed pharmaceuticals and may result in increased cautiousness by the FDA and comparable foreign
regulatory authorities in reviewing new pharmaceuticals based on

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safety, efficacy or other regulatory considerations and may result in significant delays in obtaining regulatory approvals. Any delay in obtaining, or inability to
obtain, applicable regulatory approvals would prevent us from commercializing our product candidates.

Regulatory  approval  for  our  product  candidates  by  the  FDA,  or  any  similar  regulatory  authorities  outside  the  United  States,  is  limited  to  those  specific
indications and conditions for which clinical safety and efficacy have been demonstrated.

Any regulatory approval is limited to the indications for use and related treatment of those specific diseases and indications set forth in the approval for which a
product is deemed to be safe and effective by the FDA, or other similar regulatory authorities outside the United States. In addition to the regulatory approval
required for new drug products, new formulations or indications for an approved product also require regulatory approval. If we are not able to obtain regulatory
approval for any desired future indications for our products, our ability to effectively market and sell our products may be reduced and our business may be
adversely affected.

While physicians may choose to prescribe drugs for uses that are not described in the product’s labeling and for uses that differ from those tested in clinical
studies  and  approved  by  the  regulatory  authorities  (“off-label  uses”),  our  ability  to  promote  the  products  is  limited  to  those  indications  that  are  specifically
approved by the FDA, or similar regulatory authorities outside the United States. Such off-label uses are common across medical specialties and may constitute
an  appropriate  treatment  for  some  patients  in  certain  circumstances.  Regulatory  authorities  in  the  U.S.  generally  do  not  regulate  practice  of  medicine  or  the
behavior of physicians in their choice of treatments. Regulatory authorities do, however, restrict communications by pharmaceutical companies on the promotion
of  off-label  use.  If  our  promotional  activities  fail  to  comply  with  these  regulations  or  guidelines,  we  may  be  subject  to  compliance  or  enforcement  actions,
including Warning Letters, by these authorities. In addition, our failure to follow FDA laws, regulations and guidelines relating to promotion and advertising
may cause the FDA to suspend or withdraw an approved product from the market, request a recall or institute fines or penalties, or could result in disgorgement
of money, operating restrictions, corrective advertising, injunctions or criminal prosecution, any of which could harm our business.

If any of our product candidates are approved and we or our contract manufacturer(s) fail to produce the product, or components of the product, in the
volumes that we require on a timely basis, or fail to comply with stringent regulations applicable to pharmaceutical drug manufacturers, we may face delays
in the commercialization of our product candidates or be unable to meet market demand, and may lose potential revenues.

The  manufacture  of  pharmaceutical  products  requires  significant  expertise  and  capital  investment,  including  the  development  of  advanced  manufacturing
techniques  and  process  controls,  and  the  use  of  specialized  processing  equipment.  We  may  enter  into  development  and  supply  agreements  with  contract
manufacturers for the completion of pre-commercialization manufacturing development activities and, if approved, the manufacture of commercial supplies for
one or more of our product candidates. Any termination or disruption of our relationships with our contract manufacturers may materially harm our business and
financial condition and frustrate any commercialization efforts for each respective product candidate.

All of our contract manufacturers must comply with strictly enforced federal, state and foreign regulations, including cGMP requirements enforced by the FDA
through its establishment inspection program. We are required by law to establish adequate oversight and control over raw materials, components and finished
products furnished by our third-party suppliers and contract manufacturers, but we have little control over their compliance with these regulations. Any failure to
comply with applicable regulations may result in fines and civil penalties, suspension of production, restrictions on imports and exports, suspension or delay in
product approval, product seizure or recall, or withdrawal of product approval, and would limit the availability of our product and customer confidence in our
product. Any manufacturing defect or error discovered after products have been produced and distributed could result in even more significant consequences,
including costly recalls, re-stocking costs, damage to our reputation and potential for product liability claims.

If  the  contract  manufacturers  upon  whom  we  may  rely  to  manufacture  one  or  more  of  our  product  candidates,  and  any  future  product  candidate  we  may  in-
license, fails to deliver the required commercial quantities on a timely basis at commercially reasonable prices, we would likely be unable to meet demand for
our products and we would lose potential revenues.

If  serious  adverse  or  unacceptable  side  effects  are  identified  during  the  development  of  one  or  more  of  our  product  candidates  or  any  future  product
candidate, we may need to abandon or limit the development of some of our product candidates.

If one or more of our product candidates or any future product candidate are associated with undesirable side effects or adverse events in clinical trials or have
characteristics that are unexpected, we may need to abandon their development or limit development to more narrow uses or subpopulations in which the adverse
events, undesirable side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. In our industry, many
compounds that initially showed promise in early stage testing have later

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been found to cause serious adverse events that prevented further development of the compound. In the event that our clinical trials reveal a high or unacceptable
severity and prevalence of adverse events, our trials could be suspended or terminated, and the FDA or comparable foreign regulatory authorities could order us
to cease further development or deny approval of one or more of our product candidates or any future product candidate for any or all targeted indications. The
FDA could also issue a letter requesting additional data or information prior to making a final decision regarding whether or not to approve a product candidate.
The number of requests for additional data or information issued by the FDA in recent years has increased and has resulted in substantial delays in the approval
of several new drugs. Adverse events or undesirable side effects caused by one or more of our product candidates or any future product candidate could also
result in the inclusion of unfavorable information in our product labeling or in denial of regulatory approval by the FDA or other regulatory authorities for any or
all targeted indications, which would, in turn, prevent us from commercializing and generating market acceptance and revenues from the sale of that product
candidate. Adverse events or side effects could affect patient recruitment or the ability of enrolled patients to complete the trial and could result in potential
product liability claims.

Additionally, if one or more of our product candidates or any future product candidate receives marketing approval and we or others later identify undesirable
side effects caused by this product, a number of potentially significant negative consequences could result, including:

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regulatory authorities may require the addition of unfavorable labeling statements, including specific warnings , black box warnings, adverse reactions,
precautions, and/or contraindications;

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regulatory authorities may suspend or withdraw their approval of the product, and/or require it to be removed from the market;

● we may be required to change the way the product is administered, conduct additional clinical trials or change the labeling of the product; or

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our reputation may suffer.

Any of these events could prevent us from achieving or maintaining market acceptance of any of our product candidates or any future product candidate or could
substantially increase our commercialization costs and expenses, which in turn could delay or prevent us from generating significant revenues, or any revenues,
from its sale.

Even  if  one  or  more  of  our  product  candidates  receives  regulatory  approval,  it  and  any  other  products  we  may  market  will  remain  subject  to  substantial
regulatory scrutiny.

If one or more of our product candidates that we may license or acquire is approved, the approved product candidate will be subject to ongoing requirements and
review  by  the  FDA  and  other  regulatory  authorities.  These  requirements  include  labeling,  packaging,  storage,  advertising,  promotion,  record-keeping  and
submission of safety and other post-market information and reports, registration and listing requirements, cGMP requirements relating to manufacturing, quality
control,  quality  assurance  and  corresponding  maintenance  of  records  and  documents,  requirements  regarding  the  distribution  of  samples  to  physicians  and
recordkeeping of the drug, and requirements regarding our presentations to and interactions with health care professionals.

The FDA, or other regulatory authorities, may also impose requirements for costly post-marketing studies or clinical trials and surveillance to monitor the safety
or efficacy of the product. The FDA and other applicable regulatory authorities closely regulates the post-approval marketing and promotion of drugs to ensure
drugs are marketed only for the approved indications and in accordance with the provisions of the approved labeling. The FDA and other applicable regulatory
authorities impose stringent restrictions on manufacturers’ communications regarding off-label use and if we do not market our products for only their approved
indications, we may be subject to enforcement action for off-label marketing. Violations of the FDCA relating to the promotion of prescription drugs may lead to
investigations, civil claims, and/or criminal charges alleging violations of federal and state health care fraud and abuse laws, as well as state consumer protection
laws.

In addition, later discovery of previously unknown adverse events or other problems with our products, manufacturers or manufacturing processes, or failure to
comply with regulatory requirements, may yield various results, including:

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restrictions on such products, operations, manufacturers or manufacturing processes;

restrictions on the labeling or marketing of a product;

restrictions on product distribution or use;

requirements to conduct post-marketing studies or clinical trials;

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● warning letters, untitled letters, import alerts, and/or inspection observations;

● withdrawal of the products from the market;

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

recall of products;

fines, restitution or disgorgement of profits;

suspension or withdrawal of marketing or regulatory approvals;

suspension of any ongoing clinical trials;

refusal to permit the import or export of our products;

product seizure; or

injunctions, consent decrees, and/or the imposition of civil or criminal penalties.

The FDA’s policies may change, and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our product
candidates, or negatively affect those products for which we may have already received regulatory approval, if any. If we are slow or unable to adapt to changes
in  existing  requirements  or  the  adoption  of  new  requirements  or  policies,  or  if  we  are  not  able  to  maintain  regulatory  compliance,  we  may  be  subject  to  the
various actions listed above, including losing any marketing approval that we may have obtained.

We will need to obtain FDA approval of any proposed product brand names, and any failure or delay associated with such approval may adversely impact
our business.

A  pharmaceutical  product  cannot  be  marketed  in  the  U.S.  or  other  countries  until  we  have  completed  a  rigorous  and  extensive  regulatory  review  process,
including approval of a brand name. Any brand names we intend to use for our product candidates will require approval from the FDA regardless of whether we
have secured a formal trademark registration from the USPTO. The FDA typically conducts a review of proposed product brand names, including an evaluation
of  the  potential  for  confusion  with  other  product  names.  The  FDA  may  also  object  to  a  product  brand  name  if  it  believes  the  name  inappropriately  implies
medical  claims.  If  the  FDA  objects  to  any  of  our  proposed  product  brand  names,  we  may  be  required  to  adopt  an  alternative  brand  name  for  our  product
candidates.  If  we  adopt  an  alternative  brand  name,  we  would  lose  the  benefit  of  our  existing  trademark  applications  for  such  product  candidate  and  may  be
required to expend significant additional resources in an effort to identify a suitable product brand name that would qualify under applicable trademark laws, not
infringe the existing rights of third parties and be acceptable to the FDA. We may be unable to build a successful brand identity for a new trademark in a timely
manner or at all, which would limit our ability to commercialize our product candidates.

Public concern regarding the safety of drug products could delay or limit our ability to obtain regulatory approval, result in the inclusion of unfavorable
information in our labeling, or require us to undertake other activities that may entail additional costs.

In light of widely publicized events concerning the safety risk of certain drug products, the FDA, members of the U.S. Congress, the Government Accountability
Office, medical professionals and the general public have raised concerns about potential drug safety issues. These events have resulted in the withdrawal of drug
products,  revisions  to  drug  labeling  that  further  limit  use  of  the  drug  products  and  the  establishment  of  risk  management  programs.  The  Food  and  Drug
Administration Amendments Act of 2007, or FDAAA, grants significant expanded authority to the FDA, much of which is aimed at improving the safety of drug
products  before  and  after  approval.  In  particular,  the  new  law  authorizes  the  FDA  to,  among  other  things,  require  post-approval  studies  and  clinical  trials,
mandate  changes  to  drug  labeling  to  reflect  new  safety  information  and  require  risk  evaluation  and  mitigation  strategies  for  certain  drugs,  including  certain
currently  approved  drugs.  It  also  significantly  expands  the  federal  government’s  clinical  trial  registry  and  results  databank,  which  we  expect  will  result  in
significantly increased government oversight of clinical trials. Under the FDAAA, companies that violate these and other provisions of the new law are subject
to substantial civil monetary penalties, among other regulatory, civil and criminal penalties. The increased attention to drug safety issues may result in a more
cautious approach by the FDA in its review of data from our clinical trials. Data from clinical trials may receive greater scrutiny, particularly with respect to
safety, which may make the FDA or other regulatory authorities more likely to require additional preclinical studies or clinical trials. If the FDA requires us to
conduct additional preclinical studies or clinical trials prior to approving any of our product candidates, our ability to obtain approval of this product candidate
will be delayed. If the FDA requires us

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to  provide  additional  clinical  or  preclinical  data  following  the  approval  of  any  of  our  product  candidates,  the  indications  for  which  this  product  candidate  is
approved may be limited or there may be specific warnings or limitations on dosing, and our efforts to commercialize our product candidates may be otherwise
adversely impacted.

If  we  experience  delays  or  difficulties  in  the  enrollment  of  patients  in  clinical  trials,  our  receipt  of  necessary  regulatory  approvals  could  be  delayed  or
prevented.

We may not be able to initiate or continue clinical trials for one or more of our product candidates if we are unable to locate and enroll a sufficient number of
eligible patients to participate in these trials as required by the FDA or similar regulatory authorities outside the United States. Some of our competitors have
ongoing clinical trials for product candidates that treat the same indications that we are targeting for our product candidates, and patients who would otherwise
be  eligible  for  our  clinical  trials  may  instead  enroll  in  clinical  trials  of  our  competitors’  product  candidates. Available  therapies  for  the  indications  we  are
pursuing can also affect enrollment in our clinical trials. Patient enrollment is affected by other factors including, but not necessarily limited to:

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the severity of the disease under investigation;

the eligibility criteria for the study in question;

the perceived risks and benefits of the product candidate under study;

the efforts to facilitate timely enrollment in clinical trials;

the patient referral practices of physicians;

the number of clinical trials sponsored by other companies for the same patient population;

the ability to monitor patients adequately during and after treatment; and

the proximity and availability of clinical trial sites for prospective patients.

Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays and could require us to abandon one or more clinical
trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our product candidates or future product candidates, which
would cause the value of the Company to decline and limit our ability to obtain additional financing.

If  our  competitors  develop  treatments  for  any  of  our  product  candidates’  target  indications  and  those  competitor  products  are  approved  more  quickly,
marketed more successfully or demonstrated to be more effective, the commercial opportunity for our product candidate will be reduced or eliminated.

The biotechnology and pharmaceutical industries are subject to rapid and intense technological change. We face, and will continue to face, competition in the
development and, if approved, marketing of our product candidates from academic institutions, government agencies, research institutions and biotechnology
and  pharmaceutical  companies.  There  can  be  no  assurance  that  developments  by  others  will  not  render  one  or  more  of  our  product  candidates  obsolete  or
noncompetitive.  Furthermore,  new  developments,  including  the  development  of  other  drug  technologies  and  methods  of  preventing  the  incidence  of  disease,
occur in the pharmaceutical industry at a rapid pace. These developments may render one or more of our product candidates obsolete or noncompetitive.

Competitors may seek to develop alternative formulations that do not directly infringe on our in-licensed patent rights. The commercial opportunity for one or
more of our product candidates could be significantly harmed if competitors are able to develop alternative formulations outside the scope of our in-licensed
patents. Compared to us, many of our potential competitors have substantially greater:

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capital resources;

development resources, including personnel and technology;

clinical trial experience;

regulatory experience;

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expertise in prosecution of intellectual property rights; and

● manufacturing, distribution and sales and marketing experience.

As a result of these factors, our competitors may obtain regulatory approval of their products more rapidly than we are able to or may obtain patent protection or
other intellectual property rights that limit our ability to develop or commercialize one or more of our product candidates. Our competitors may also develop
drugs that are more effective, safe, useful and less costly than ours and may be more successful than us in manufacturing and marketing their products. Smaller
or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies.
We  will  also  face  competition  from  these  third  parties  in  establishing  clinical  trial  sites,  in  patient  registration  for  clinical  trials,  and  in  identifying  and  in-
licensing new product candidates.

Further,  generic  therapies  are  typically  sold  at  lower  prices  than  branded  therapies  and  are  generally  preferred  by  hospital  formularies  and  managed  care
providers of health services. We anticipate that, if approved, our product candidates will face increasing competition in the form of generic versions of branded
products of competitors, including those that have lost or will lose their patent exclusivity. In the future, we may face additional competition from a generic form
of our own candidates when the patents covering them begin to expire, or earlier if the patents are successfully challenged. If we are unable to demonstrate to
physicians and payers that the key differentiating features of our product candidates translate to overall clinical benefit or lower cost of care, we may not be able
to compete with generic alternatives.

If any of our product candidates are successfully developed but do not achieve broad market acceptance among physicians, patients, healthcare payors and
the medical community, the revenues that any such product candidates generate from sales will be limited.

Even if our product candidates receive regulatory approval, they may not gain market acceptance among physicians, patients, healthcare payors and the medical
community. Coverage and reimbursement of our product candidates by third-party payors, including government payors, generally would also be necessary for
commercial success. The degree of market acceptance of any approved products would depend on a number of factors, including, but not necessarily limited to:

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the efficacy and safety as demonstrated in clinical trials;

the timing of market introduction of such product candidate as well as competitive products;

the clinical indications for which the product is approved;

acceptance by physicians, major operators of cancer clinics and patients of the product as a safe and effective treatment;

the safety of such product candidates seen in a broader patient group, (i.e., based on actual use);

the availability, cost and potential advantages of alternative treatments, including less expensive generic drugs;

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

changes in regulatory requirements by government authorities for our product candidates;

the relative convenience and ease of administration of the product candidate for clinical practices;

the  product  labeling  or  product  insert  required  by  the  FDA  or  regulatory  authority  in  other  countries,  including  any  contradictions,  warnings,  drug
interactions, or other precautions;

changes in the standard of care for the targeted indications for our product  candidate  or  future  product  candidates,  which  could  reduce  the  marketing
impact of any labeling or marketing claims that we could make following FDA approval;

the approval, availability, market acceptance and reimbursement for a companion diagnostic, if any;

the prevalence and severity of adverse side effects; and

the effectiveness of our sales and marketing efforts.

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If any product candidate that we develop does not provide a treatment regimen that is as beneficial as, or is not perceived as being as beneficial as, the current
standard  of  care  or  otherwise  does  not  provide  patient  benefit,  that  product  candidate,  if  approved  for  commercial  sale  by  the  FDA  or  other  regulatory
authorities, likely will not achieve market acceptance. Our ability to effectively promote and sell any approved products will also depend on pricing and cost-
effectiveness, including our ability to produce a product at a competitive price and our ability to obtain sufficient third-party coverage or reimbursement. If any
product  candidate  is  approved  but  does  not  achieve  an  adequate  level  of  acceptance  by  physicians,  patients  and  third-party  payors,  our  ability  to  generate
revenues from that product would be substantially reduced. In addition, our efforts to educate the medical community and third-party payors on the benefits of
our product candidates may require significant resources, may be constrained by FDA rules and policies on product promotion, and may never be successful.

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

There is significant uncertainty related to the third-party coverage and reimbursement of newly approved drugs. Such third-party payors include government
health programs such as Medicare, managed care providers, private health insurers and other organizations. We intend to seek approval to market our product
candidates in the U.S., the EU and other selected foreign jurisdictions. Market acceptance and sales of our product candidates in both domestic and international
markets will depend significantly on the availability of adequate coverage and reimbursement from third-party payors for any of our product candidates and may
be affected by existing and future health care reform measures. Government and other third-party payors are increasingly attempting to contain healthcare costs
by  limiting  both  coverage  and  the  level  of  reimbursement  for  new  drugs  and,  as  a  result,  they  may  not  cover  or  provide  adequate  payment  for  our  product
candidates. These payors may conclude that our product candidates are less safe, less effective or less cost-effective than existing or future introduced products,
and third-party payors may not approve our product candidates for coverage and reimbursement or may cease providing coverage and reimbursement for these
product candidates.

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  to  the  payor  supporting  scientific,  clinical  and  cost-effectiveness  data  for  the  use  of  our  products.  We  may  not  be  able  to  provide  data
sufficient to gain acceptance with respect to coverage and reimbursement. If reimbursement of our future products is unavailable or limited in scope or amount,
or if pricing is set at unsatisfactory levels, we may be unable to achieve or sustain profitability.

In  some  foreign  countries,  particularly  in  the  EU,  the  pricing  of  prescription  pharmaceuticals  is  subject  to  governmental  control.  In  these  countries,  pricing
negotiations with governmental authorities can take considerable time after the receipt of marketing approval for a product candidate. To obtain reimbursement
or pricing approval in some countries, we may be required to conduct additional clinical trials that compare the cost-effectiveness of our product candidates to
other available therapies. If reimbursement of our product candidates is unavailable or limited in scope or amount in a particular country, or if pricing is set at
unsatisfactory levels, we may be unable to achieve or sustain profitability of our products in such a country.

If  we  are  unable  to  establish  sales,  marketing  and  distribution  capabilities  or  to  enter  into  agreements  with  third  parties  to  market  and  sell  our  product
candidates, we may be unsuccessful in commercializing our product candidates, if they are approved.

We currently do not have a marketing or sales organization for the marketing, sales and distribution of pharmaceutical products. In order to commercialize any
approved product candidate, we would need to build marketing, sales, distribution, managerial and other non-technical capabilities or arrange for third parties to
perform these services, and we may be unsuccessful in doing so. In the event of successful development and regulatory approval of any of our current or future
product candidates, we expect to build a targeted specialist sales force to market or co-promote the product. 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, but are not necessarily limited to:

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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 or persuade adequate numbers of physicians to prescribe any future products;

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

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unforeseen costs and expenses associated with creating our own sales and marketing organization.

We  face  potential  product  liability  exposure,  and  if  successful  claims  are  brought  against  us,  we  may  incur  substantial  liability  for  one  or  more  of  our
product candidates or a future product candidate we may license or acquire and may have to limit their commercialization.

The use of one or more of our product candidates and any future product candidate we may license or acquire in clinical trials and the sale of any products for
which we obtain marketing approval expose us to the risk of product liability claims. For example, we may be sued if any product we develop allegedly causes
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 or a breach of warranties. Product
liability claims might be brought against us by consumers, health care providers or others using, administering or selling our products. If we cannot successfully
defend ourselves against these claims, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

● withdrawal of clinical trial participants;

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suspension or termination of clinical trial sites or entire trial programs;

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

initiation of investigations by regulators;

impairment of our business reputation;

costs of related litigation;

substantial monetary awards to patients or other claimants;

loss of revenues;

reduced resources of our management to pursue our business strategy; and

the inability to commercialize our product candidate or future product candidates.

We will obtain limited product liability insurance coverage for any and all of our upcoming clinical trials. However, our insurance coverage may not reimburse
us or may not be sufficient to reimburse us for any expenses or losses we may suffer. Moreover, insurance coverage is becoming increasingly expensive, and, in
the future, we may not be able to maintain insurance coverage at a reasonable cost or in sufficient amounts to protect us against losses due to liability. When
needed we intend to expand our insurance coverage to include the sale of commercial products if we obtain marketing approval for one or more of our product
candidates in development, but we may be unable to obtain commercially reasonable product liability insurance for any products approved for marketing. On
occasion, large judgments have been awarded in class action lawsuits based on drugs that had unanticipated side effects. A successful product liability claim or
series of claims brought against us could cause our stock price to fall and, if judgments exceed our insurance coverage, could decrease our cash and adversely
affect our business.

Product candidates, even if successfully developed and commercialized, may be effective only in combating certain specific types of cancer, and the market
for drugs designed to combat such cancer type(s) may be small and unprofitable.

There  are  many  different  types  of  cancer,  and  a  treatment  that  is  effective  against  one  type  of  cancer  may  not  be  effective  against  another.  CAR  T  or  other
technologies we pursue may only be effective in combating specific types of cancer but not others. Even if one or more of our products proves to be an effective
treatment against a given type of cancer, the number of patients suffering from such cancer may be small, in which case potential sales from a therapy designed
to combat such cancer would be limited.

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Our gene therapy product candidates are based on a novel technology, which makes it difficult to predict the time and cost of product candidate development
and subsequently obtaining regulatory approval.

We have concentrated a portion of our therapeutic product research and development efforts on our gene therapy platform, and our future success depends, in
part, on the successful development of this therapeutic approach. There can be no assurance that any development problems we experience in the future related
to our gene therapy platform will not cause significant delays or unanticipated costs, or that such development problems can be solved. We may also experience
delays in developing a sustainable, reproducible and commercial-scale manufacturing process or transferring that process to commercial partners, which may
prevent us from completing our clinical studies or commercializing our products on a timely or profitable basis, if at all.

In addition, the clinical study requirements of the FDA, the European Medicines Agency, or EMA, and other regulatory agencies and the criteria these regulators
use to determine the safety and efficacy of a product candidate vary substantially according to the type, complexity, novelty and intended use and market of the
potential  products.  The  regulatory  approval  process  for  novel  product  candidates  such  as  ours  can  be  more  expensive  and  take  longer  than  for  other,  better
known  or  more  extensively  studied  pharmaceutical  or  other  product  candidates.  Currently,  a  limited  number  of  gene  therapy  products,  including  CAR  T
therapies, have been approved by the FDA, the EMA and the European Commission. Given the few precedents of approved gene therapy products, it is difficult
to  determine  how  long  it  will  take  or  how  much  it  will  cost  to  obtain  regulatory  approvals  for  our  product  candidates  in  the  United  States,  the  EU  or  other
jurisdictions. Approvals by the EMA and the European Commission may not be indicative of what the FDA may require for approval.

Regulatory requirements governing the development of gene therapy products have changed frequently and may continue to change in the future. The FDA has
established the Office of Tissues and Advanced Therapies within the Center for Biologics Evaluation and Research, or CBER, to consolidate the review of gene
therapy and related products, and to advise the CBER on its review. The FDA can put an IND on clinical hold if the information in an IND is not sufficient to
assess the risks in pediatric patients. Before a clinical study can begin at any institution, that institution’s IRB and its Institutional Biosafety Committee will have
to review the proposed clinical study to assess the safety of the study. Moreover, serious adverse events or developments in clinical trials of gene therapy product
candidates  conducted  by  others  may  cause  the  FDA  or  other  regulatory  bodies  to  initiate  a  clinical  hold  on  our  clinical  trials  or  otherwise  change  the
requirements for approval of any of our product candidates.

These  regulatory  review  agencies,  committees  and  advisory  groups  and  the  new  requirements  and  guidelines  they  promulgate  may  lengthen  the  regulatory
review process, require us to perform additional or larger studies, increase our development costs, lead to changes in regulatory positions and interpretations,
delay  or  prevent  approval  and  commercialization  of  these  treatment  candidates  or  lead  to  significant  post-approval  studies,  limitations  or  restrictions. As  we
advance  our  product  candidates,  we  will  be  required  to  consult  with  these  regulatory  and  advisory  groups  and  comply  with  applicable  requirements  and
guidelines. If we fail to do so, we may be required to delay or discontinue development of our product candidates. Delay or failure to obtain, or unexpected costs
in  obtaining,  the  regulatory  approval  necessary  to  bring  a  potential  product  to  market  could  decrease  our  ability  to  generate  sufficient  product  revenue  to
maintain our business.

Negative public opinion and increased regulatory scrutiny of the therapies that underpin many of our product candidates may damage public perception of
our product candidates or adversely affect our ability to conduct our business or obtain regulatory approvals for our product candidates.

Public perception may be influenced by claims that one or more of the therapies underpinning our product candidates, including without limitation gene therapy,
is unsafe, and such therapy may not gain the acceptance of the public or the medical community. In particular, the success of our gene therapy platforms will
depend  upon  physicians  specializing  in  the  treatment  of  those  diseases  that  our  product  candidates  target  prescribing  treatments  that  involve  the  use  of  our
product candidates in lieu of, or in addition to, existing treatments with which they are already familiar and for which greater clinical data may be available.
More restrictive government regulations or negative public opinion would have a negative effect on our business or financial condition and may delay or impair
the development and commercialization of our product candidates or demand for any products we may develop. Adverse events in our clinical trials, even if not
ultimately attributable to our product  candidates,  and  the  resulting  publicity,  could  lead  to  increased  governmental  regulation,  unfavorable  public  perception,
potential  regulatory  delays  in  the  testing  or  approval  of  our  potential  product  candidates,  stricter  labeling  requirements  for  those  product  candidates  that  do
obtain approval and/or a decrease in demand for any such product candidates. Concern about environmental spread of our products, whether real or anticipated,
may also hinder the commercialization of our products.

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Risks Related to Reliance on Third Parties

We  rely,  and  expect  to  continue  to  rely,  on  third  parties  to  conduct  our  preclinical  studies  and  clinical  trials,  and  those  third  parties  may  not  perform
satisfactorily, including failing to meet deadlines for the completion of such trials or complying with applicable regulatory requirements.

We rely on our licensors to conduct some of our preclinical studies and some of our clinical trials for our product candidates and for future product candidates,
and we rely on third-party CROs and site management organizations to conduct most of the remainder of our preclinical studies and all the rest of our clinical
trials.  We  expect  to  continue  to  rely  on  third  parties,  such  as  our  licensors,  CROs,  site  management  organizations,  clinical  data  management  organizations,
medical institutions and clinical investigators, to conduct some of our preclinical studies and all of our clinical trials. The agreements with these third parties
might terminate for a variety of reasons, including a failure to perform by the third parties. If we need to enter into alternative arrangements, that could delay our
product development activities.

Our reliance on these third parties for research and development activities reduces our control over these activities but does not relieve us of our responsibilities.
For  example,  we  remain  responsible  for  ensuring  that  each  of  our  preclinical  studies  and  clinical  trials  are  conducted  in  accordance  with  the  general
investigational plan and protocols for the trial and for ensuring that our preclinical studies are conducted in accordance with good laboratory practices (“GLPs”)
as appropriate. Moreover, the FDA requires us to comply with standards, commonly referred to as good clinical practices (“GCPs”) for conducting, recording
and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial
participants are protected. Regulatory authorities enforce these requirements through periodic inspections of trial sponsors, clinical investigators and trial sites. If
we  or  any  of  our  CROs  fail  to  comply  with  applicable  GCPs,  the  clinical  data  generated  in  our  clinical  trials  may  be  deemed  unreliable  and  the  FDA  or
comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure you
that upon inspection by a regulatory authority, such regulatory authority will determine that any of our clinical trials complies with GCP regulations. In addition,
our  clinical  trials  must  be  conducted  with  product  produced  under  cGMP  regulations.  Our  failure  to  comply  with  these  regulations  may  require  us  to  repeat
clinical  trials,  which  would  delay  the  regulatory  approval  process.  We  also  are  required  to  register  ongoing  clinical  trials  and  post  the  results  of  completed
clinical trials on a government-sponsored database, ClinicalTrials.gov, within specified timeframes. Failure to do so can result in fines, adverse publicity and
civil and criminal sanctions.

The third parties with whom we have contracted to help perform our preclinical studies and/or clinical trials may also have relationships with other entities, some
of which may be our competitors. If these third parties do not successfully carry out their contractual duties, meet expected deadlines or conduct our preclinical
studies  or  clinical  trials  in  accordance  with  regulatory  requirements  or  our  stated  protocols,  we  will  not  be  able  to  obtain,  or  may  be  delayed  in  obtaining,
marketing approvals for our product candidates and will not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates.

If  any  of  our  relationships  with  these  third-party  CROs  or  site  management  organizations  terminates,  we  may  not  be  able  to  enter  into  arrangements  with
alternative CROs or site management organizations or to do so on commercially reasonable terms. Switching or adding additional CROs or site management
organizations  involves  additional  cost  and  requires  management  time  and  focus.  In  addition,  there  is  a  natural  transition  period  when  a  new  CRO  or  site
management organization commences work. As a result, delays could occur, which could compromise our ability to meet our desired development timelines.
Though we carefully manage our relationships with our CROs or site management organizations, there can be no assurance that we will not encounter similar
challenges  or  delays  in  the  future.  Forces  beyond  our  control,  including  the  impacts  of  COVID-19,  could  disrupt  the  ability  of  our  third-party  CROs,  site
management  organizations,  clinical  data  management  organizations,  medical  institutions,  and  clinical  investigators  to  conduct  our  preclinical  studies  and  our
clinical trials for our product candidates and for any future product candidate. As of the date of this Annual Report on Form 10-K, the Company has experienced
a moderate impact on its long-term development timeline and its liquidity due to the worldwide spread of the COVID-19 virus.

We are currently reliant on COH, Fred Hutch, St. Jude, UAB, Mayo Clinic, and LUMC for a substantial portion of our research and development efforts
and the early clinical testing of our product candidates.

A  substantial  portion  of  our  research  and  development  has  been  and  will  continue  to  be  conducted  by  COH,  Fred  Hutch,  St.  Jude,  UAB,  LUMC  and  Mayo
Clinic pursuant to a sponsored research agreement and/or clinical trial agreements with each of those parties. As a result, our future success is heavily dependent
on the results of research and development efforts of Dr. Stephen Forman and his team at COH, of Drs. Brian Till and Mazyar Shadman and their team at Fred
Hutch, of Drs. Stephen Gottschalk and Ewelina Mamcarz and their team at St. Jude, of Dr. James M. Markert and his team at UAB, of Dr. Frank J. Staal and his
team at LUMC, and of Dr. Larry R. Pease and his team at Mayo Clinic. We have limited control over the nature or timing of their research and limited visibility
into their day-to-day activities, and as a result can provide little assurance that their efforts will be successful.

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We contract with third parties for the manufacture of our product candidates for preclinical and clinical testing and may also do so for commercialization, if
and when our product candidates are approved. This reliance on third parties increases the risk that we will not have sufficient quantities of our product
candidates  or  any  future  product  candidate  or  such  quantities  at  an  acceptable  cost,  which  could  delay,  prevent  or  impair  our  development  or
commercialization efforts.

We may rely on third-party manufacturers or third-party collaborators for the manufacture of commercial supply of one or more product candidates for which
our  collaborators  or  we  obtain  marketing  approval.  We  may  be  unable  to  establish  any  agreements  with  third-party  manufacturers  or  to  do  so  on  acceptable
terms. Even if we are able to establish agreements with third-party manufacturers, reliance on third-party manufacturers entails additional risks, including, but
not necessarily limited to:

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reliance on the third party for regulatory compliance and quality assurance, while still being required by law to establish adequate oversight and control
over products furnished by that third party;

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the possible breach of the manufacturing agreement by the third party;

● manufacturing  delays  if  our  third-party  manufacturers  are  unable  to  obtain  raw  materials  due  to  supply  chain  disruptions,  give  greater  priority  to  the
supply of other products over our product candidates or otherwise do not satisfactorily perform according to the terms of the agreement between us;

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the possible misappropriation of our proprietary information, including our trade secrets and know-how; and

the possible termination or nonrenewal of the agreement by the third party at a time that is costly or inconvenient for us.

We  rely  on  our  third-party  manufacturers  to  produce  or  purchase  from  third-party  suppliers  the  materials  and  equipment  necessary  to  produce  our  product
candidates for our preclinical and clinical trials. Forces beyond our control, including the effects of the COVID-19 pandemic, could disrupt the global supply
chain and impact our or our third-party manufacturers’ ability to obtain raw materials or other products necessary to manufacture our product candidates. There
are a limited number of suppliers for raw materials and equipment that we use (or that are used on our behalf) to manufacture our drugs, and there may be a need
to assess alternate suppliers to prevent a possible disruption of the manufacture of the materials and equipment necessary to produce our product candidates for
our preclinical and clinical trials, and if approved, ultimately for commercial sale. We do not have any control over the process or timing of the acquisition of
these raw materials or equipment by our third-party manufacturers. Any significant delay in the supply of a product candidate, or the raw material components
thereof, for an ongoing preclinical or clinical trial due to the need to replace a third-party manufacturer could considerably delay completion of our preclinical or
clinical trials, product testing and potential regulatory approval of our product candidates. If our manufacturers or we are unable to purchase these raw materials
or  equipment  after  regulatory  approval  has  been  obtained  for  our  product  candidates,  the  commercial  launch  of  our  product  candidates  would  be  delayed  or
there would be a shortage in supply, which would impair our ability to generate revenues from the sale of our product candidates.

The facilities used by contract manufacturers to potentially manufacture our product candidates must be approved by the FDA pursuant to inspections that will
be conducted after we submit an NDA or BLA to the FDA. We are required by law to establish adequate oversight and control over raw materials, components
and finished products furnished by our contract manufacturers, but we do not control  the  day-to-day  manufacturing  operations  of,  and  are  dependent  on,  the
contract manufacturers for compliance with cGMP regulations for manufacture of our product candidates. Third-party manufacturers may not be able to comply
with the cGMP regulations or similar regulatory requirements outside the United States. Our failure, or the failure of our third-party manufacturers, to comply
with applicable regulations could result in sanctions being imposed on us, including clinical holds, fines, injunctions, restrictions on imports and exports, civil
penalties,  delays,  suspension  or  withdrawal  of  approvals,  license  revocation,  seizures  or  recalls  of  product  candidates  or  products,  operating  restrictions  and
criminal prosecutions, any of which could significantly and adversely affect supplies of our products.

One or more of the product candidates that we may develop may compete with other product candidates and products for access to manufacturing facilities.
There are a limited number of manufacturers that operate under cGMP regulations and that might be capable of manufacturing for us. Any performance failure
on the part of our existing or future manufacturers could delay clinical development or marketing approval. We do not currently have arrangements in place for
redundant supply. If our current contract manufacturers cannot perform as agreed, we may be required to replace such manufacturers. We may incur added costs
and delays in identifying and qualifying any replacement manufacturers. The DEA restricts the importation of a controlled substance finished drug product when
the same substance is commercially available in the United States, which could reduce the number of potential alternative manufacturers for one or more of our
product candidates.

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Future  dependence  upon  others  for  the  manufacture  of  our  product  candidates  or  products  may  adversely  affect  our  future  profit  margins  and  our  ability  to
commercialize any products that may receive marketing approval on a timely and competitive basis.

We also expect to rely on other third parties to distribute drug supplies for our clinical trials. Any performance failure on the part of our distributors could delay
clinical  development  or  marketing  approval  of  our  product  candidates  or  commercialization  of  our  products,  if  approved,  producing  additional  losses  and
depriving us of potential product revenue.

We rely on third parties to conduct all aspects of our lentiviral vector production and these third parties may not perform satisfactorily.

We  do  not  independently  conduct  our  lentiviral  vector  production  and  we  currently  rely,  and  expect  to  continue  to  rely,  on  third  parties  with  respect  to  the
manufacture of these items.

Our reliance on these third parties for manufacturing lentiviral vector reduces our control over these activities but will not relieve us of our responsibility to
ensure compliance with all required regulations and study protocols. For products that we develop and commercialize, we will remain responsible for ensuring
that  each  of  our  IND-enabling  studies  and  clinical  studies  is  conducted  in  accordance  with  the  study  plan  and  protocols,  and  that  our  lentiviral  vectors  are
manufactured in accordance with GMP as applied in the relevant jurisdictions.

If  these  third  parties  do  not  successfully  carry  out  their  contractual  duties,  meet  expected  deadlines,  conduct  our  studies  in  accordance  with  regulatory
requirements or our stated study plans and protocols, or manufacture our lentiviral vectors in accordance with GMP, we will not be able to complete, or may be
delayed in completing, the preclinical and clinical studies and manufacturing process validation activities required to support future IND, market authorization
application and BLA submissions and approval of our product candidates, or to support commercialization of our products, if approved. Many of our agreements
with these third parties contain termination provisions that allow these third parties to terminate their relationships with us at any time. If we need to enter into
alternative arrangements, our product development and commercialization activities could be delayed.

We may be forced to enter into an agreement with a different manufacturer, which we may not be able to do on reasonable terms, if at all. In some cases, the
technical skills required to manufacture lentiviral vector for our drug product candidates may be unique or proprietary to the original manufacturer, and we may
have difficulty or there may be contractual restrictions prohibiting us from, transferring such skills to a back-up or alternate supplier, or we may be unable to
transfer such skills at all. Any of these events could lead to clinical study delays or failure to obtain marketing approval or impact our ability to successfully
commercialize our product or any future products. Some of these events could be the basis for FDA action, including injunction, recall, seizure or total or partial
suspension of production.

We rely on clinical data and results obtained by third parties that could ultimately prove to be inaccurate or unreliable.

As part of our strategy to mitigate development risk, we seek to develop product candidates with well-studied mechanisms of action, and we utilize biomarkers to
assess potential clinical efficacy early in the development process. This strategy necessarily relies upon clinical data and other results obtained by third parties
that  may  ultimately  prove  to  be  inaccurate  or  unreliable.  Further,  such  clinical  data  and  results  may  be  based  on  products  or  product  candidates  that  are
significantly  different  from  our  product  candidates  or  any  future  product  candidate.  If  the  third-party  data  and  results  we  rely  upon  prove  to  be  inaccurate,
unreliable or not applicable to our product candidates or future product candidate, we could make inaccurate assumptions and conclusions about our product
candidates and our research and development efforts could be compromised.

We may need to license certain intellectual property from third parties, and such licenses may not be available or may not be available on commercially
reasonable terms.

A third party may hold intellectual property, including patent rights that are important or necessary to the development and commercialization of our products. It
may  be  necessary  for  us  to  use  the  patented  or  proprietary  technology  of  third  parties,  who  may  or  may  not  be  interested  in  granting  such  a  license,  to
commercialize our products, in which case we would be required to obtain a license from these third parties on commercially reasonable terms, or our business
could be harmed, possibly materially.

Collaborative  relationships  with  third  parties  could  cause  us  to  expend  significant  resources  and  incur  substantial  business  risk  with  no  assurance  of
financial return.

Establishing  strategic  collaborations  is  difficult  and  time-consuming.  Our  discussions  with  potential  collaborators  may  not  lead  to  the  establishment  of
collaborations  on  favorable  terms,  if  at  all.  Potential  collaborators  may  reject  collaborations  based  upon  their  assessment  of  our  financial,  regulatory  or
intellectual property position. In addition, there has been a significant number of recent business combinations

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among  large  pharmaceutical  companies  that  have  resulted  in  a  reduced  number  of  potential  future  collaborators.  Even  if  we  successfully  establish  new
collaborations, these relationships may never result in the successful development or commercialization of product candidates or the generation of sales revenue.
To the extent that we enter into collaborative arrangements, the related product revenues are likely to be lower than if we directly marketed and sold products.
Such collaborators may also consider alternative product candidates or technologies for similar indications that may be available to collaborate on and whether
such a collaboration could be more attractive than the one with us for any future product candidate.

Risks Relating to Legislation and Regulation Affecting the Biopharmaceutical and Other Industries

We  are  subject  to  new  legislation,  regulatory  proposals  and  managed  care  initiatives  that  may  increase  our  costs  of  compliance  and  adversely  affect  our
ability to market our products, obtain collaborators and raise capital.

Legislative  and  regulatory  changes  to  the  healthcare  systems  of  the  United  States  and  certain  foreign  countries  could  impact  our  ability  to  sell  our  products
profitably.  Several  federal  agencies  including  FDA,  CMS  and  HHS,  in  addition  to  state  and  local  governments  regulate  drug  product  development  and
marketing. In particular, the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (“MMA”) changed the way Medicare covers and pays
for pharmaceutical products by revising the payment methodology for many products reimbursed by Medicare, resulting in lower rates of reimbursement for
many types of drugs, and added a prescription drug benefit to the Medicare program that involves commercial plans negotiating drug prices for their members. In
addition, this law provided authority for limiting the number of drugs that will be covered in any therapeutic class. Cost reduction initiatives and other provisions
of this law and future laws could decrease the coverage and price that we will receive for any approved products. While the MMA only applies to drug benefits
for Medicare beneficiaries, private payors often follow Medicare coverage policy and payment limitations in setting their own payment rates. Therefore, any
limitations in reimbursement that results from the MMA may result in reductions in payments from private payors.

Since 2003, there have been several other legislative and regulatory changes to the coverage and reimbursement landscape for pharmaceuticals. In March 2010,
the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010, collectively, the “Affordable Care
Act” or “ACA,” was enacted in 2010 and made significant changes to the United States’ healthcare system. The ACA and any revisions or replacements of that
Act, any substitute legislation, and other changes in the law or regulatory framework could have a material adverse effect on our business.

Among the provisions of the ACA of importance to our potential product candidates are:

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an  annual,  nondeductible  fee  on  any  entity  that  manufactures,  or  imports  specified  branded  prescription  drugs  and  biological  products,  apportioned
among these entities according to their market share in certain government healthcare programs;

an increase in the statutory minimum rebates a manufacturer must pay under the Medicaid Drug Rebate Program to 23.1% and 13.0% of the average
manufacturer price for branded and generic drugs, respectively;

expansion  of  healthcare  fraud  and  abuse  laws,  including  the  federal  False  Claims  Act  and  the  federal  Anti-Kickback  Statute,  new  government
investigative powers and enhanced penalties for non-compliance;

a  new  Medicare  Part  D  coverage  gap  discount  program,  in  which  manufacturers  must  agree  to  offer  point-of-sale  discounts  off  negotiated  prices  of
applicable brand drugs to eligible beneficiaries during their coverage gap period, as a condition for a manufacturer’s outpatient drugs to be covered under
Medicare Part D;

extension  of  a  manufacturer’s  Medicaid  rebate  liability  to  covered  drugs  dispensed  to  individuals  who  are  enrolled  in  Medicaid  managed  care
organizations;

expansion of eligibility criteria for Medicaid programs by, among other things, allowing states to offer Medicaid coverage to additional individuals and
by adding new mandatory eligibility categories for certain individuals with income at or below 138% of the federal poverty level, thereby potentially
increasing a manufacturer’s Medicaid rebate liability;

expansion of the entities eligible to enroll in the 340B Drug Pricing Program to include certain critical access hospitals, freestanding cancer hospitals,
rural referral centers, and sole community hospitals, but exempting certain drugs from the ceiling price requirements for these covered entities;

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the new requirements under the federal Open Payments program and its implementing regulations;

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a new requirement to annually report drug samples that manufacturers and distributors provide to physicians;

a new regulatory pathway for the approval of biosimilar biological products, all of which will impact existing government healthcare programs and will
result in the development of new programs; and

a new Patient-Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with
funding for such research.

The Supreme Court upheld the ACA in the main challenge to the constitutionality of the law in 2012. Specifically, the Supreme Court held that the individual
mandate and corresponding penalty was constitutional because it would be considered a tax by the federal government. The Supreme Court also upheld federal
subsidies for purchasers of insurance through federally facilitated exchanges in a decision released in June 2015.

At  the  end  of  2017,  Congress  passed  the  Tax  Cuts  and  Jobs Act,  which  repealed  the  penalty  for  individuals  who  fail  to  maintain  minimum  essential  health
coverage as required by the ACA.

The Bipartisan Budget Act of 2018, the “BBA,” which set government spending levels for Fiscal Years 2018 and 2019, revised certain provisions of the ACA.
Specifically, beginning in 2019, the BBA increased manufacturer point-of-sale discounts off negotiated prices of applicable brand drugs in the Medicare Part D
coverage  gap  from  50%  to  70%,  ultimately  increasing  the  liability  for  brand  drug  manufacturers.  Further,  this  mandatory  manufacturer  discount  applied  to
biosimilars beginning in 2019.

In  the  United  States  there  is  significant  interest  in  containing  healthcare  costs  and  increasing  scrutiny  of  pharmaceutical  pricing  practices.  Congress  has
continually  explored  legislation  intended  to  address  the  cost  of  prescription  drugs.  Notably,  the  major  committees  of  jurisdiction  in  the  Senate  (Finance
Committee,  Health,  Education,  Labor  and  Pensions  Committee,  and  Judiciary  Committee),  regularly  evaluate  and  hold  hearings  on  legislation  intended  to
address various elements of the prescription drug supply chain and prescription drug pricing. Proposals include a significant overhaul of the Medicare Part D
benefit  design,  efforts  to  cap  the  increase  in  drug  prices,  create  drug  price  transparency,  and  efforts  to  allow  the  Secretary  of  the  Department  of  Health  and
Human  Services  to  negotiate  drug  prices  with  prescription  drug  manufacturers.  While  we  cannot  predict  what  proposals  may  ultimately  become  law,  the
elements under consideration could significantly change the landscape in which the pharmaceutical market operates.

The  former  Trump  administration  took  several  regulatory  steps  and  proposed  numerous  prescription  drug  cost  control  measures.  Similarly,  the  Biden
administration  has  identified  promoting  competition  and  lowering  drug  prices  as  a  priority.  State  legislatures  are  similarly  active  in  proposing  and  passing
legislation and regulations aimed at controlling pharmaceutical and biological prices and drug cost transparency. There likely will continue to be legislative and
regulatory proposals at the federal and state levels directed at broadening the availability of healthcare and containing or lowering the cost of healthcare products
and  services,  including  prescription  drugs.  We  cannot  predict  the  initiatives  that  may  be  adopted  in  the  future.  The  continuing  efforts  of  the  government,
insurance companies, managed care organizations and other payors of healthcare services to contain or reduce costs of healthcare and prescription drugs may
adversely affect:

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the demand for any products for which we may obtain regulatory approval;

our ability to set a price that we believe is fair for our products;

our ability to generate revenues and achieve or maintain profitability;

the level of taxes that we are required to pay; and

the availability of capital.

We expect that the ACA, 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  receive  for  any  approved  drug.  Any  reduction  in  reimbursement  from  Medicare  or  other  government
healthcare programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare
reforms may prevent us from being able to generate revenue, attain profitability or commercialize our drugs.

Legislative  and  regulatory  proposals  have  been  made  to  expand  post-approval  requirements  and  restrict  sales  and  promotional  activities  for  pharmaceutical
products. We cannot be sure whether additional legislative changes will be enacted, or whether the FDA regulations,

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guidance  or  interpretations  will  be  changed,  or  what  the  impact  of  such  changes  on  the  marketing  approvals  of  our  product  candidates,  if  any,  may  be.  In
addition, increased scrutiny by the U.S. Congress of the FDA’s approval process may significantly delay or prevent marketing approval, as well as subject us to
more stringent product labeling and post-marketing testing and other requirements.

Changes  in  funding  for  the  FDA  and  other  government  agencies  could  hinder  their  ability  to  hire  and  retain  key  leadership  and  other  personnel,  or
otherwise prevent new products and services from being developed or commercialized in a timely manner, which could negatively impact our business or the
business of our partners.

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, ability to 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. In addition, government funding of other government agencies 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 drugs to be reviewed and/or approved by necessary government agencies,
which  would  adversely  affect  our  business  or  the  business  of  our  partners.  For  example,  over  the  last  several  years,  including  for  35  days  beginning  on
December 22, 2018, the U.S. government has shut down several times and certain regulatory agencies, such as the FDA, have had to furlough nonessential FDA
employees and stop routine 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. If the timing of FDA’s review and approval of new products is
delayed,  the  timing  of  our  or  our  partners’  development  process  may  be  delayed,  which  could  result  in  delayed  milestone  revenues  and  materially  harm  our
operations or business.

The  COVID-19  pandemic  has  caused  considerable  disruptions  at  the  FDA,  namely  with  respect  to  diverting  the  FDA’s  attention  and  resources  to  facilitate
vaccine  development  and  ensure  rapid  review  and  emergency  use  authorization  of  vaccines  intended  to  prevent  COVID-19.  Continued  focus  on  COVID-19
countermeasures, and the reorganization and rededication for critical resources, both at the FDA and within similar governmental authorities across the world,
may impact the ability of new products and services from being developed or commercialized in a timely manner.

Our  current  and  future  relationships  with  customers  and  third-party  payors  in  the  United  States  and  elsewhere  may  be  subject,  directly  or  indirectly,  to
applicable anti-kickback, fraud and abuse, false claims, transparency, health information privacy and security and other healthcare laws and regulations,
which could expose us to  criminal  sanctions,  civil  penalties,  contractual  damages,  reputational  harm,  administrative  burdens  and  diminished  profits  and
future earnings.

Healthcare providers, physicians and third-party payors in the U.S. and elsewhere will play a primary role in the recommendation and prescription of any product
candidates for which we obtain marketing approval. Our future arrangements with third-party payors and customers may expose us to broadly applicable fraud
and abuse and other healthcare laws and regulations, including, without limitation, the federal Anti-Kickback Statute and the federal False Claims Act, which
may constrain the business or financial arrangements and relationships through which we sell, market and distribute any product candidates for which we obtain
marketing approval. In addition, we may be subject to transparency laws and patient privacy regulation by the federal and state governments and by governments
in foreign jurisdictions in which we conduct our business. The applicable federal, state and foreign healthcare laws and regulations that may affect our ability to
operate include, but are not necessarily limited to:

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the federal Anti-Kickback Statute, which prohibits, among other things, persons from knowingly and willfully soliciting, offering, receiving or providing
remuneration, directly or indirectly, in cash or in kind, to induce or reward, or in return for, either the referral of an individual for, or the purchase, order
or recommendation of, any good or service, for which payment may be made under federal and state healthcare programs, such as Medicare and
Medicaid;

federal civil and criminal false claims laws and civil monetary penalty laws, including the federal False Claims Act, which impose criminal and civil
penalties, including civil whistleblower or qui tam actions, against individuals or entities for knowingly presenting, or causing to be presented, to the
federal government, including the Medicare and Medicaid programs, claims for payment that are false or fraudulent or making a false statement to avoid,
decrease or conceal an obligation to pay money to the federal government; the federal Health Insurance Portability and Accountability Act of 1996
(“HIPAA”), which imposes criminal and civil liability for executing a scheme to defraud any healthcare benefit program or making false statements
relating to healthcare matters;

● HIPAA,  as  amended  by  the  Health  Information  Technology  for  Economic  and  Clinical  Health  Act  of  2009  (“HITECH”),  and  their  respective

implementing regulations, which impose obligations on covered healthcare providers, health plans, and healthcare

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clearinghouses, as well as their business associates that create, receive, maintain or transmit individually identifiable health information for or on behalf
of a covered entity, with respect to safeguarding the privacy, security and transmission of individually identifiable health information;

the federal Open Payments program, which requires manufacturers of certain approved drugs, devices, biologics and medical supplies for which payment
is available under Medicare, Medicaid or the Children’s Health Insurance Program, with specific exceptions, to report annually to the CMS, information
related  to  “payments  or  other  transfers  of  value”  made  to  physicians,  which  is  defined  to  include  doctors,  dentists,  optometrists,  podiatrists  and
chiropractors, and teaching hospitals and applicable manufacturers and applicable group purchasing organizations to report annually to CMS ownership
and investment interests held by the physicians and their immediate family members. Data collection began on August 1, 2013, with requirements for
manufacturers to submit reports to CMS by June 30, 2014, and 90 days after the end each subsequent calendar year. Disclosure of such information was
made by CMS on a publicly available website beginning in September 2014 and is annually updated; and

analogous state and foreign laws and regulations, such as state anti-kickback and false claims laws, which may apply to sales or marketing arrangements
and claims involving healthcare items or services reimbursed by non-governmental third-party payors, including private insurers; state and foreign laws
that  require  pharmaceutical  companies  to  comply  with  the  pharmaceutical  industry’s  voluntary  compliance  guidelines  and  the  relevant  compliance
guidance promulgated by the federal government or otherwise restrict payments that may be made to healthcare providers; state and foreign laws that
require  drug  manufacturers  to  report  information  related  to  payments  and  other  transfers  of  value  to  physicians  and  other  healthcare  providers  or
marketing expenditures; and state and foreign laws governing the privacy and security 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.

Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations may involve substantial costs. It
is  possible  that  governmental  authorities  will  conclude  that  our  business  practices  may  not  comply  with  current  or  future  statutes,  regulations  or  case  law
involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other
governmental  regulations  that  may  apply  to  us,  we  may  be  subject  to  significant  civil,  criminal  and  administrative  penalties,  including,  without  limitation,
damages,  fines,  imprisonment,  exclusion  from  participation  in  government  healthcare  programs,  such  as  Medicare  and  Medicaid,  and  the  curtailment  or
restructuring of our operations, which could have a material adverse effect on our business. If any of the physicians or other healthcare providers or entities with
whom  we  expect  to  do  business,  including  our  collaborators,  is  found  not  to  be  in  compliance  with  applicable  laws,  it  may  be  subject  to  criminal,  civil  or
administrative sanctions, including exclusions from participation in government healthcare programs, which could also materially affect our business.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could harm
our business.

We  are  subject  to  numerous  environmental,  health  and  safety  laws  and  regulations,  including  those  governing  laboratory  procedures  and  the  handling,  use,
storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals
and biological materials. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and
wastes. We cannot eliminate the risk of contamination or injury from these materials. Although we believe that the safety procedures for handling and disposing
of these materials comply with the standards prescribed by these laws and regulations, we cannot eliminate the risk of accidental contamination or injury from
these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any
liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such
laws and regulations.

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.

In addition, 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.

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Risks Related to Intellectual Property and Potential Disputes Thereof

If  we  are  unable  to  obtain  and  maintain  sufficient  patent  protection  for  our  technology  and  products,  our  competitors  could  develop  and  commercialize
technology and products similar or identical to ours, and our ability to successfully commercialize our technology and products may be impaired.

Our  success  depends,  in  large  part,  on  our  ability  to  obtain  patent  protection  for  product  candidates  and  their  formulations  and  uses.  The  patent  application
process is subject to numerous risks and uncertainties, and there can be no assurance that we or our partners will be successful in obtaining patents or what the
scope of an issued patent may ultimately be. These risks and uncertainties include, but are not necessarily limited to, the following:

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patent applications may not result in any patents being issued, or the scope of issued patents may not extend to competitive product candidates and their
formulations and uses developed or produced by others;

● our competitors, many of which have substantially greater resources than us or our partners, and many of which have made significant investments in
competing technologies, may seek, or may already have obtained, patents that may limit or interfere with our abilities to make, use, and sell potential
product candidates, file new patent applications, or may affect any pending patent applications that we may have;

● there may be significant pressure on the U.S. government and other international governmental bodies to limit the scope of patent protection both inside

and outside the United States for disease treatments that prove successful as a matter of public policy regarding worldwide health concerns; and

● countries other than the United States may have patent laws less favorable to patentees than those upheld by U.S. courts, allowing foreign competitors a

better opportunity to create, develop and market competing products.

In addition, patents that may be issued or in-licensed may be challenged, invalidated, modified, revoked, circumvented, found to be unenforceable, or otherwise
may  not  provide  any  competitive  advantage.  Moreover,  we  may  be  subject  to  a  third-party  pre-issuance  submission  of  prior  art  to  the  USPTO,  or  become
involved in opposition, derivation, reexamination, inter partes review, post-grant review or interference proceedings challenging our patent rights or the patent
rights of others. The costs of these proceedings could be substantial, and it is possible that our efforts to establish priority of invention would be unsuccessful,
resulting in a material adverse effect on our U.S. patent positions. An adverse determination in any such submission, patent office trial, proceeding or litigation
could reduce the scope of, render unenforceable, or invalidate, our patent rights, allow third parties to commercialize our technologies or products and compete
directly  with  us,  without  payment  to  us,  or  result  in  our  inability  to  manufacture  or  commercialize  products  without  infringing  third-party  patent  rights.  In
addition, if the breadth or strength of protection provided by our patents and patent applications is threatened, it could dissuade companies from collaborating
with us to license, develop or commercialize current or future product candidates. Third parties are often responsible for maintaining patent protection for our
product candidates, at our and their expense. If that party fails to appropriately prosecute and maintain patent protection for a product candidate, our abilities to
develop  and  commercialize  products  may  be  adversely  affected,  and  we  may  not  be  able  to  prevent  competitors  from  making,  using  and  selling  competing
products.  Such  a  failure  to  properly  protect  intellectual  property  rights  relating  to  any  of  our  product  candidates  could  have  a  material  adverse  effect  on  our
financial condition and results of operations. In addition, U.S. patent laws may change, which could prevent or limit us from filing patent applications or patent
claims to protect products and/or technologies or limit the exclusivity periods that are available to patent holders, as well as affect the validity, enforceability, or
scope of issued patents.

We and our licensors also rely on trade secrets and proprietary know-how to protect product candidates. Although we have taken steps to protect our and their
trade  secrets  and  unpatented  know-how,  including  entering  into  confidentiality  and  non-use  agreements  with  third  parties,  and  proprietary  information  and
invention assignment agreements with employees, consultants and advisers, third parties may still come upon this same or similar information independently.
Despite  these  efforts,  any  of  these  parties  may  also  breach  the  agreements  and  may  unintentionally  or  willfully  disclose  our  or  our  licensors’  proprietary
information, including our trade secrets, and we may not be able to identify such breaches or obtain adequate remedies. Enforcing a claim that a party illegally
disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and
outside the United States are less willing or unwilling to protect trade secrets. Moreover, if any of our or our licensors’ trade secrets were to be lawfully obtained
or independently developed by a competitor, we and our licensors would have no right to prevent them, or those to whom they communicate it, from using that
technology or information to compete with us. If any of our or our licensors’ trade secrets were to be disclosed to or independently developed by a competitor,
our competitive positions would be harmed.

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The patent prosecution process is expensive and time-consuming, and we may not be able to file and prosecute all necessary or desirable patent applications at a
reasonable  cost  or  in  a  timely  manner.  It  is  also  possible  that  we  will  fail  to  identify  any  patentable  aspects  of  our  research  and  development  output  and
methodology, and, even if we do, an opportunity to obtain patent protection may have passed. Given the uncertain and time-consuming process of filing patent
applications and prosecuting them, it is possible that our product(s) or process(es) originally covered by the scope of the patent application may have changed or
been modified, leaving our product(s) or process(es) without patent protection. If our licensors or we fail to obtain or maintain patent protection or trade secret
protection for one or more product candidates or any future product candidate we may license or acquire, third parties may be able to leverage our proprietary
information  and  products  without  risk  of  infringement,  which  could  impair  our  ability  to  compete  in  the  market  and  adversely  affect  our  ability  to  generate
revenues  and  achieve  profitability.  Moreover,  should  we  enter  into  other  collaborations  we  may  be  required  to  consult  with  or  cede  control  to  collaborators
regarding the prosecution, maintenance and enforcement of licensed patents. Therefore, these patents and applications may not be prosecuted and enforced in a
manner consistent with the best interests of our business.

The  patent  position  of  biotechnology  and  pharmaceutical  companies  generally  is  highly  uncertain,  involves  complex  legal  and  factual  questions  and  has  in
recent years been the subject of much litigation. In addition, no consistent policy regarding the breadth of claims allowed in pharmaceutical or biotechnology
patents has emerged to date in the U.S. The patent situation outside the U.S. is even more uncertain. The laws of foreign countries may not protect our rights to
the same extent as the laws of the U.S., and we may fail to seek or obtain patent protection in all major markets. For example, European patent law restricts the
patentability of methods of treatment of the human body more than U.S. law does. Publications of discoveries in the scientific literature often lag behind the
actual discoveries, and patent applications in the U.S. and other jurisdictions are typically not published until 18 months after a first filing, or in some cases not
at  all.  Therefore,  we  cannot  know  with  certainty  whether  we  or  our  licensors  were  the  first  to  make  the  inventions  claimed  in  patents  or  pending  patent
applications that we own or licensed, or that we or our licensors were the first to file for patent protection of such inventions. In the event that a third party has
also filed a U.S. patent application relating to our product candidates or a similar invention, depending upon the priority dates claimed by the competing parties,
we may have to participate in interference proceedings declared by the USPTO to determine priority of invention in the U.S. We might also become involved in
derivation proceedings in an event that a third party misappropriates one or more of our inventions and files their own patent application directed to such one or
more inventions. The costs of these proceedings could be substantial, and it is possible that our efforts to establish priority of invention (or that a third party
derived an invention from us) would be unsuccessful, resulting in a material adverse effect on our U.S. patent position. As a result, the issuance, scope, validity,
enforceability and commercial value of our patent rights are highly uncertain. Our pending and future patent applications may not result in patents being issued
which protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products.
Changes in either the patent laws or interpretation of the patent laws in the U.S. and other countries may diminish the value of our patents or narrow the scope of
our patent protection. For example, the federal courts of the U.S. have taken an increasingly dim view of the patent eligibility of certain subject matter, such as
naturally occurring nucleic acid sequences, amino acid sequences and certain methods of utilizing the same, which include their detection in a biological sample
and diagnostic conclusions arising from their detection. Such subject matter, which had long been a staple of the biotechnology and biopharmaceutical industry
to protect their discoveries, is now considered, with few exceptions, ineligible in the first instance for protection under the patent laws of the U.S. Accordingly,
we cannot predict the breadth of claims that may be allowed and remain enforceable in our patents or in those licensed from a third party.

Even if our patent applications issue as patents, they may not issue in a form that will provide us with any meaningful protection, prevent competitors from
competing  with  us  or  otherwise  provide  us  with  any  competitive  advantage.  Our  competitors  may  be  able  to  circumvent  our  owned  or  licensed  patents  by
developing similar or alternative technologies or products in a non-infringing manner.

We also may rely on the regulatory period of market exclusivity for any of our biologic product candidates that are successfully developed and approved for
commercialization. Although this period in the United States is generally 12 years from the date of marketing approval (depending on the nature of the specific
product),  there  is  a  risk  that  the  U.S.  Congress  could  amend  laws  to  significantly  shorten  this  exclusivity  period.  Once  any  regulatory  period  of  exclusivity
expires, depending on the status of our patent coverage and the nature of the product, we may not be able to prevent others from marketing products that are
biosimilar to or interchangeable with our products, which would materially adversely affect our business.

We depend on our licensors to maintain and enforce the intellectual property covering certain of our product candidates. We have limited, if any, control
over the resources that our licensors can or will devote to securing, maintaining, and enforcing patents protecting our product candidates.

We depend on our licensors to protect the proprietary rights covering our product candidates and we have limited, if any, control over the amount or timing of
resources that they devote on our behalf, or the priority they place on, maintaining patent rights and prosecuting patent applications to our advantage. Moreover,
we have limited, if any, control over the strategies and arguments employed in the maintenance of

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patent rights and the prosecution of patent applications to our advantage. Our licensors might become involved in disputes with one of their other licensees, and
we or a portion of our licensed patent rights might become embroiled in such disputes.

Our licensors, depending on the patent or application, are responsible for maintaining issued patents and prosecuting patent applications. We cannot be sure that
they will perform as required. Should they decide they no longer want to maintain any of the patents licensed to us, they are required to afford us the opportunity
to do so at our expense. If our licensors do not perform, and if we do not assume the maintenance of the licensed patents in sufficient time to make required
payments  or  filings  with  the  appropriate  governmental  agencies,  we  risk  losing  the  benefit  of  all  or  some  of  those  patent  rights.  Moreover,  and  possibly
unbeknownst to us, our licensors may experience serious difficulties related to their overall business or financial stability, and they may be unwilling or unable
to  continue  to  expend  the  financial  resources  required  to  maintain  and  prosecute  these  patents  and  patent  applications.  While  we  intend  to  take  actions
reasonably necessary to enforce our patent rights, we depend, in part, on our licensors to protect a substantial portion of our proprietary rights and to inform us of
the status of those protections and efforts thereto.

Our licensors may also be notified of alleged infringement and be sued for infringement of third-party patents or other proprietary rights. We may have limited,
if any, control or involvement over the defense of these claims, and our licensors could be subject to injunctions and temporary or permanent exclusionary orders
in the U.S. or other countries. Our licensors are not obligated to defend or assist in our defense against third-party claims of infringement. We have limited, if
any, control over the amount or timing of resources, if any, that our licensors devote on our behalf or the priority they place on defense of such third-party claims
of infringement.

Because of the uncertainty inherent in any patent or other litigation involving proprietary rights, we or our licensors may not be successful in defending claims of
intellectual property infringement alleged by third parties, which could have a material adverse effect on our results of operations. Regardless of the outcome of
any litigation, defending the litigation may be expensive, time-consuming and distracting to management.

Protecting our proprietary rights is difficult and costly, and we may be unable to ensure their protection.

The degree of future protection for our proprietary rights is uncertain, because legal means afford only limited protection and may not adequately protect our
rights or permit us to gain or keep our competitive advantage, in addition to being costly and time consuming to undertake. For example:

●

●

●

●

●

●

our licensors might not have been the first to make the inventions covered by each of our pending patent applications and issued patents;

our licensors might not have been the first to file patent applications for these inventions;

others may independently develop similar or alternative technologies or duplicate our product candidates or any future product candidate technologies;

it is possible that none of the pending patent applications licensed to us will result in issued patents;

the scope of our issued patents may not extend to competitive products developed or produced by others;

the issued patents covering our product candidates or any future product candidate may not provide a basis for market exclusivity for active products,
may not provide us with any competitive advantages, or may be challenged by third parties;

● we may not develop additional proprietary technologies that are patentable; or

●

intellectual property rights of others may have an adverse effect on our business.

We  may  become  involved  in  lawsuits  to  protect  or  enforce  our  patents  or  other  intellectual  property,  which  could  be  expensive,  time  consuming  and
unsuccessful, and an unfavorable outcome in any litigation would harm our business.

Competitors may infringe our issued patents or other intellectual property. To counter infringement or unauthorized use, we may be required to file one or more
actions for patent infringement, which can be expensive and time consuming. Any claims we assert against accused infringers could provoke these parties to
assert counterclaims against us alleging that we infringe their patents; or provoke those parties to petition the USPTO to institute inter partes review against the
asserted patents, which may lead to a finding that all or some of the claims of the patent are invalid. In addition, in a patent infringement proceeding, a court may
decide that a patent of ours is invalid or unenforceable,

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in whole or in part, construe the patent’s claims narrowly or 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 or as a matter of public policy. An adverse result in any litigation proceeding could put one or more of our patents at risk of
being  invalidated,  rendered  unenforceable,  or  interpreted  narrowly.  Furthermore,  adverse  results  on  U.S.  patents  may  affect  related  patents  in  our  global
portfolio.

If we or our licensors are sued for infringing intellectual property rights of third parties, it will be costly and time consuming, and an unfavorable outcome
in that litigation would have a material adverse effect on our business.

Our  success  also  depends  on  our  ability,  and  the  abilities  of  any  of  our  respective  current  or  future  collaborators,  to  develop,  manufacture,  market  and  sell
product candidates without infringing the proprietary rights of third parties. Numerous U.S. and foreign issued patents and pending patent applications, which
are owned by third parties, exist in the fields in which we are developing products, some of which may be directed at claims that overlap with the subject matter
of our or our licensors’ intellectual property. Because patent applications can take many years to issue, there may be currently pending applications, unknown to
us, which may later result in issued patents that our product candidates or proprietary technologies may infringe. Similarly, there may be issued patents relevant
to  our  product  candidates  of  which  we  or  our  licensors  are  not  aware.  Publications  of  discoveries  in  the  scientific  literature  often  lag  behind  the  actual
discoveries, and patent applications in the U.S. and other jurisdictions are typically not published until 18 months after a first filing, or in some cases not at all.
Therefore, we cannot know with certainty whether we or such licensors were the first to make the inventions claimed in patents or pending patent applications
that we own or licensed, or that we and our licensors were the first to file for patent protection of such inventions. In the event that a third party has also filed a
U.S. patent application relating to our product candidates or a similar invention, depending upon the priority dates claimed by the competing parties, we may
have to participate in interference proceedings declared by the USPTO to determine priority of invention in the U.S. The costs of these proceedings could be
substantial, and it is possible that our efforts to establish priority of invention would be unsuccessful, resulting in a material adverse effect on our U.S. patent
position. As a result, the issuance, scope, validity, enforceability and commercial value of our or any of our licensors’ patent rights are highly uncertain.

There is a substantial amount of litigation involving patent and other intellectual property rights in the biotechnology and biopharmaceutical industries generally.
If a third party claims that we or any of our licensors, suppliers or collaborators infringe the third party’s intellectual property rights, we may have to, among
other things:

●

●

●

●

●

obtain additional licenses, which may not be available on commercially reasonable terms, if at all;

abandon  an  infringing  product  candidate  or  redesign  products  or  processes  to  avoid  infringement,  which  may  demand  substantial  funds,  time  and
resources and which may result in inferior or less desirable processes and/or products;

pay substantial damages, including the possibility of treble damages and attorneys’ fees, if a court decides that the product or proprietary technology at
issue infringes on or violates the third party’s rights;

pay substantial royalties, fees and/or grant cross-licenses to our product candidates; and/or

defend litigation or administrative proceedings which may be costly regardless of outcome, and which could result in a substantial diversion of financial
and management resources.

Intellectual property litigation could cause us to spend substantial resources and distract our personnel from their normal responsibilities.

Even if resolved in our favor, litigation or other legal proceedings relating to intellectual property claims may cause us to incur significant expenses and could
distract our technical and management personnel from their normal responsibilities. In addition, there could be public announcements of the results of hearings,
motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, it could have a substantial
adverse  effect  on  the  price  of  our  common  stock.  Such  litigation  or  proceedings  could  substantially  increase  our  operating  losses  and  reduce  the  resources
available for development activities or any future sales, marketing or distribution activities. We may not have sufficient financial or other resources to conduct
such litigation or proceedings adequately. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we
can  because  of  their  greater  financial  resources.  Uncertainties  resulting  from  the  initiation  and  continuation  of  patent  litigation  or  other  proceedings  could
compromise our ability to compete in the marketplace.

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If  we  fail  to  comply  with  our  obligations  under  our  intellectual  property  licenses  and  third  party  funding  arrangements,  we  could  lose  rights  that  are
important to our business.

We  are  currently  a  party  to  license  agreements  with  St.  Jude,  COH,  Fred  Hutch,  University  of  California  at  Los Angeles  (“UCLA”),  Nationwide  and  other
institutions. In the future, we may become party to licenses that are important for product development and commercialization. If we fail to comply with our
obligations  under  current  or  future  license  and  funding  agreements,  our  counterparties  may  have  the  right  to  terminate  these  agreements,  in  which  event  we
might not be able to develop, manufacture or market any product or utilize any technology that is covered by these agreements or may face other penalties under
the agreements. Such an occurrence could materially and adversely affect the value of a product candidate being developed under any such agreement or could
restrict our drug discovery activities. Termination of these agreements or reduction or elimination of our rights under these agreements may result in our having
to  negotiate  new  or  reinstated  agreements  with  less  favorable  terms,  or  cause  us  to  lose  our  rights  under  these  agreements,  including  our  rights  to  important
intellectual property or technology.

We may be subject to claims that our employees and/or consultants have wrongfully used or disclosed to us alleged trade secrets of their former employers
or other clients.

As is common in the biopharmaceutical industry, we rely on employees and consultants to assist in the development of product candidates, many of whom were
previously  employed  at,  or  may  have  previously  been  or  are  currently  providing  consulting  services  to,  other  biopharmaceutical  companies,  including  our
competitors or potential competitors. We may become subject to claims related to whether these individuals have inadvertently or otherwise used, disclosed or
misappropriated trade secrets or other proprietary information of their former employers or their former or current clients. Litigation may be necessary to defend
against these claims. Even if we are successful in defending these claims, litigation could result in substantial costs and be a distraction to management and/or the
employees or consultants that are implicated.

If we are unable to protect the confidentiality of our trade secrets, our business and competitive position would be harmed.

In addition to seeking patent protection for our product candidates or any future product candidate, we also rely on trade secrets, including unpatented know-
how, technology and other proprietary information, to maintain our competitive position, particularly where we do not believe patent protection is appropriate or
obtainable. However, trade secrets are difficult to protect. We limit disclosure of such trade secrets where possible but we also seek to protect these trade secrets,
in part, by entering into non-disclosure and confidentiality agreements with parties who do have access to them, such as our employees, our licensors, corporate
collaborators,  outside  scientific  collaborators,  contract  manufacturers,  consultants,  advisors  and  other  third  parties.  We  also  enter  into  confidentiality  and
invention or patent assignment agreements with our employees and consultants. Despite these efforts, any of these parties may breach the agreements and may
unintentionally  or  willfully  disclose  our  proprietary  information,  including  our  trade  secrets,  and  we  may  not  be  able  to  obtain  adequate  remedies  for  such
breaches.  Enforcing  a  claim  that  a  party  illegally  disclosed  or  misappropriated  a  trade  secret  is  difficult,  expensive  and  time-consuming,  and  the  outcome  is
unpredictable. In addition, some courts inside and outside the United States are less willing or unwilling to protect trade secrets. Moreover, if any of our trade
secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them, or those to whom they communicate
it, from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor,
our competitive position would be harmed.

We  in-license  intellectual  property  pertaining  to  certain  product  candidates  from  third  parties.  As  such,  any  dispute  with  the  licensors  or  the  non-
performance of such license agreements may adversely affect our ability to develop and commercialize the applicable product candidates.

The types of disputes which may arise between us and the third parties from whom we license intellectual property include, but are not limited to:

●

●

●

the scope of rights granted under such license agreements 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 such license agreements;

the scope and interpretation of the representations and warranties made to us by our licensors, including those pertaining to the licensors’ right title and
interest in the licensed technology and the licensors’ right to grant the licenses contemplated by such agreements;

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●

●

the sublicensing of patent and other rights under our license agreements and/or collaborative development relationships, and the rights and obligations
associated with such sublicensing, including whether or not a given transaction constitutes a sublicense under such license agreement;

the  diligence  and  development  obligations  under  license  agreements  (which  may  include  specific  diligence  milestones)  and  what  activities  or
achievements satisfy those diligence obligations;

● whether or not the milestones associated with certain milestone payment obligations have been achieved or satisfied;

●

●

●

●

the applicability or scope of indemnification claims or obligations under such license agreements;

the permissibility and advisability of, and strategy regarding, the pursuit of potential third-party infringers of the intellectual property that is the subject of
such license agreements;

the calculation of royalty, sublicense revenue and other payment obligations under such license agreements;

the extent to which license rights, if any, are retained by licensors under such license agreements;

● whether or not a material breach has occurred under such license agreements and the extent to which such breach, if deemed to have occurred, is or can

be cured within applicable cure periods, if any;

●

●

disputes regarding patent filing and prosecution decisions, as well as payment obligations regarding past and ongoing patent expenses;

intellectual  property  rights  resulting  from  the  joint  creation  or  use  of  intellectual  property  (including  improvements  made  to  licensed  intellectual
property) by our and our partners’ licensors and us and our partners; and

●

the priority of invention of patented technology.

In addition, the agreements under which we currently license intellectual property or technology from third parties are complex, and certain provisions in such
agreements may be susceptible to multiple interpretations or may conflict in such a way that puts us in breach of one or more agreements, which would make us
susceptible to lengthy and expensive disputes with one or more of such third-party licensing partners. 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 agreements, 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, which could
have a material adverse effect on our business, financial conditions, results of operations and prospects.

Fortress controls a voting majority of our common stock.

Risks Relating to Our Control by Fortress

Pursuant to the terms of the Class A Preferred Stock held by Fortress, Fortress is entitled to cast, for each share of Class A Preferred held by Fortress, the number
of votes that is equal to one and one-tenth (1.1) times a fraction, the numerator of which is the sum of (A) the shares of outstanding common stock and (B) the
whole  shares  of  common  stock  into  which  the  shares  of  outstanding  Class  A  common  shares  and  the  Class  A  Preferred  Stock  are  convertible  and  the
denominator  of  which  is  the  number  of  shares  of  outstanding  Class A  Preferred  Stock. Accordingly,  Fortress  is  able  to  control  or  significantly  influence  all
matters requiring approval by our stockholders, including the election of directors and the approval of mergers or other business combination transactions. The
interests  of  Fortress  may  not  always  coincide  with  the  interests  of  other  stockholders,  and  Fortress  may  take  actions  that  advance  its  own  interests  and  are
contrary to the desires of our other stockholders. Moreover, this concentration of voting power may delay, prevent or deter a change in control of us even when
such a change may be in the best interests of all stockholders, could deprive our stockholders of an opportunity to receive a premium for their common stock as
part of a sale of Mustang or our assets, and might affect the prevailing market price of our common stock.

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Fortress has the right to receive a significant grant of shares of our common stock annually which will result in the dilution of your holdings of common
stock upon each grant, which could reduce their value.

Under the terms of the Second Amended and Restated Founders Agreement (the “Founders Agreement”), which became effective July 22, 2016, Fortress will
receive a grant of shares of our common stock equal to two and one-half percent (2.5%) of the gross amount of any equity or debt financing. Additionally, the
Class A Preferred Stock, as a class, will receive an annual dividend on January 1st, payable in shares of common stock in an amount equal to two and one-
half percent (2.5%) of our fully-diluted outstanding capital stock as of the business day immediately prior to January 1st of such year. Fortress currently owns all
outstanding shares of Class A Preferred Stock. These share issuances to Fortress and any other holder of Class A Preferred Stock will dilute your holdings in our
common  stock  and,  if  the  value  of  Mustang  has  not  grown  proportionately  over  the  prior  year,  would  result  in  a  reduction  in  the  value  of  your  shares.  The
Founders Agreement  has  a  term  of  15  years  and  renews  automatically  for  subsequent  one-year  periods  unless  terminated  by  Fortress  or  upon  a  Change  in
Control (as defined in the Founders Agreement).

We might have received better terms from unaffiliated third parties than the terms we receive in our agreements with Fortress.

The agreements we have entered into with Fortress include a Management Services Agreement and the Founders Agreement. While we believe the terms of
these agreements are reasonable, they might not reflect terms that would have resulted from arm’s-length negotiations between unaffiliated third parties. The
terms of the agreements relate to, among other things, payment of a royalty on product sales and the provision of employment and transition services. We might
have received better terms from third parties because, among other things, third parties might have competed with each other to win our business.

The dual roles of our directors who also serve in similar roles with Fortress could create a conflict of interest and will require careful monitoring by our
independent directors.

We share some directors with Fortress which could create conflicts of interest between the two companies in the future. While we believe that the Founders
Agreement and the Management Services Agreement were negotiated by independent parties on both sides on arm’s length terms, and the fiduciary duties of
both parties were thereby satisfied, in the future situations may arise under the operation of both agreements that may create a conflict of interest. We will have
to be diligent to ensure that any such situation is resolved by independent parties. In particular, under the Management Services Agreement, Fortress and its
affiliates are free to pursue opportunities which could potentially be of interest to Mustang, and they are not required to notify Mustang prior to pursuing such
opportunities. Any such conflict of interest or pursuit by Fortress of a corporate opportunity independent of Mustang could expose us to claims by our investors
and creditors and could harm our results of operations.

General Risks

Our business and operations would suffer in the event of computer system failures, cyber-attacks, or deficiencies in our or third parties’ cybersecurity.

We are increasingly dependent upon information technology systems, infrastructure, and data to operate our business. In the ordinary course of business, we
collect,  store,  and  transmit  confidential  information,  including,  but  not  limited  to,  information  related  to  our  intellectual  property  and  proprietary  business
information, personal information, and other confidential information. It is critical that we maintain such confidential information in a manner that preserves its
confidentiality  and  integrity.  Furthermore,  we  have  outsourced  elements  of  our  operations  to  third  party  vendors,  who  each  have  access  to  our  confidential
information, which increases our disclosure risk.

We are in the process of implementing our internal security and business continuity measures and developing our information technology infrastructure. Our
internal  computer  systems  and  those  of  current  and  future  third  parties  on  which  we  rely  may  fail  and  are  vulnerable  to  damage  from  computer  viruses  and
unauthorized  access.  Our  information  technology  and  other  internal  infrastructure  systems,  including  corporate  firewalls,  servers,  data  center  facilities,  lab
equipment, and connection to the internet, face the risk of breakdown or other damage or interruption from service interruptions, system malfunctions, natural
disasters, terrorism, war, and telecommunication and electrical failures, as well as security breaches from inadvertent or intentional actions by our employees,
contractors,  consultants,  business  partners,  and/or  other  third  parties,  or  from  cyber-attacks  by  malicious  third  parties  (including  the  deployment  of  harmful
malware, ransomware, denial-of-service attacks, social engineering and other means to affect service reliability and threaten the confidentiality, integrity and
availability of information), each of which could compromise our system infrastructure or lead to the loss, destruction, alteration, disclosure, or dissemination of,
or damage or unauthorized access to, our data or data that is processed or maintained on our behalf, or other assets.

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If such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our development programs and our business
operations, and could result in financial, legal, business, and reputational harm to us.

In  addition,  the  loss  or  corruption  of,  or  other  damage  to,  clinical  trial  data  from  completed  or  future  clinical  trials  could  result  in  delays  in  our  regulatory
approval  efforts  and  significantly  increase  our  costs  to  recover  or  reproduce  the  data.  Likewise,  we  rely  on  third  parties  for  the  manufacture  of  our  drug
candidates or any future drug candidates and to conduct clinical trials, and similar events relating to their systems and operations could also have a material
adverse  effect  on  our  business  and  lead  to  regulatory  agency  actions.  The  risk  of  a  security  breach  or  disruption,  particularly  through  cyber-attacks  or  cyber
intrusion,  including  by  computer  hackers,  foreign  governments,  and  cyber  terrorists,  has  generally  increased  as  the  number,  intensity,  and  sophistication  of
attempted  attacks  and  intrusions  from  around  the  world  have  increased.  Sophisticated  cyber  attackers  (including  foreign  adversaries  engaged  in  industrial
espionage) are skilled at adapting to existing security technology and developing new methods of gaining access to organizations’ sensitive business data, which
could result in the loss of proprietary information, including trade secrets. We may not be able to anticipate all types of security threats, and we may not be able
to implement preventive measures effective against all such security threats. The techniques used by cyber criminals change frequently, may not be recognized
until launched, and can originate from a wide variety of sources, including outside groups such as external service providers, organized crime affiliates, terrorist
organizations, or hostile foreign governments or agencies.

Any security breach or other event leading to the loss or damage to, or unauthorized access, use, alteration, disclosure, or dissemination of, personal information,
including personal information regarding clinical trial subjects, contractors, directors, or employees, our intellectual property, proprietary business information,
or  other  confidential  or  proprietary  information,  could  directly  harm  our  reputation,  enable  competitors  to  compete  with  us  more  effectively,  compel  us  to
comply  with  federal  and/or  state  breach  notification  laws  and  foreign  law  equivalents,  subject  us  to  mandatory  corrective  action,  or  otherwise  subject  us  to
liability  under  laws  and  regulations  that  protect  the  privacy  and  security  of  personal  information.  Each  of  the  foregoing  could  result  in  significant  legal  and
financial  exposure  and  reputational  damage  that  could  adversely  affect  our  business.  Notifications  and  follow-up  actions  related  to  a  security  incident  could
impact our reputation or cause us to incur substantial costs, including legal and remediation costs, in connection with these measures and otherwise in connection
with any actual or suspected security breach. We expect to incur significant costs in an effort to detect and prevent security incidents and otherwise implement
our internal security and business continuity measures, and actual, potential, or anticipated attacks  may  cause  us  to  incur  increasing  costs,  including  costs  to
deploy additional personnel and protection technologies, train employees, and engage third-party experts and consultants.

The  costs  related  to  significant  security  breaches  or  disruptions  could  be  material,  and  our  insurance  policies  may  not  be  adequate  to  compensate  us  for  the
potential  losses  arising  from  any  such  disruption  in,  or  failure  or  security  breach  of,  our  systems  or  third-party  systems  where  information  important  to  our
business  operations  or  commercial  development  is  stored  or  processed.  In  addition,  such  insurance  may  not  be  available  to  us  in  the  future  on  economically
reasonable terms, or at all. Further, our insurance may not cover all claims made against us and could have high deductibles in any event, and defending a suit,
regardless of its merit, could be costly and divert management attention. Furthermore, if the information technology systems of our third-party vendors and other
contractors and consultants become subject to disruptions or security breaches, we may have insufficient recourse against such third parties and we may have to
expend  significant  resources  to  mitigate  the  impact  of  such  an  event,  and  to  develop  and  implement  protections  to  prevent  future  events  of  this  nature  from
occurring.

Major public health issues, and specifically the pandemic caused by the spread of COVID-19, could have an adverse impact on our financial condition and
results of operations and other aspects of our business.

In December 2019, a novel strain of coronavirus, COVID-19, was first detected in Wuhan, China, and has since spread around the world. On March 11, 2020,
the  World  Health  Organization  declared  that  the  rapidly  spreading COVID-19 outbreak  had  evolved  into  a  pandemic.  In  response  to  the  pandemic,  many
governments around the world are implementing a variety of measures to reduce the spread of COVID-19, including travel restrictions and bans, instructions to
residents to practice social distancing, quarantine advisories, shelter-in-place orders and required closures of non-essential businesses.

The  COVID-19  pandemic  has  negatively  impacted  the  global  economy,  disrupted  global  supply  chains,  and  created  significant  volatility  and  disruption  of
financial markets. Although COVID-19 has not had a material adverse effect on our business to date, no assurance can be given that it will not in the future if the
situation persists or worsens. The extent to which the coronavirus impacts our business and operating results will depend on future developments that are highly
uncertain and cannot be accurately predicted, including new information that may emerge concerning the coronavirus and the actions to contain the coronavirus
or treat its impact, among others.

Should the coronavirus continue to spread, our business operations could be delayed or interrupted. For instance, our preclinical research and clinical trials have
been affected in the past by the pandemic, and they may be affected again in the future should the pandemic return

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to previous levels of severity. Similarly, the FDA has identified COVID-19 as an important contributor to delays in response to sponsors and in scheduling of
requested  meetings,  and  it  is  not  clear  at  the  present  time  that  such  delays  have  subsided.  Site  initiation,  participant  recruitment  and  enrollment,  participant
dosing, distribution of clinical trial materials, study monitoring and data analysis may be paused or delayed due to changes in hospital or university policies,
federal,  state  or  local  regulations,  prioritization  of  hospital  resources  toward  pandemic  efforts,  or  other  reasons  related  to  the  pandemic.  If  the  coronavirus
continues to spread, some participants and clinical investigators may not be able to comply with clinical trial protocols. For example, quarantines or other travel
limitations (whether voluntary or required) may impede participant movement, affect sponsor access to study sites, or interrupt healthcare services, and we may
be  unable  to  conduct  our  clinical  trials.  Infections  and  deaths  related  to  the  pandemic  may  disrupt  the  United  States’  and  other  countries’  healthcare  and
healthcare  regulatory  systems.  Such  disruptions  could  divert  healthcare  resources  away  from,  or  materially  delay  FDA  or  other  regulatory  review  and/or
approval with respect to, our clinical trials. It is unknown how long these disruptions could continue, were they to occur. Any elongation or de-prioritization of
our clinical trials or delay in regulatory review resulting from such disruptions could materially affect the development and study of our product candidates.

We currently rely on third parties, such as contract laboratories, CROs, medical institutions and clinical investigators to conduct these studies and clinical trials.
If these third parties themselves are adversely impacted by restrictions resulting from the coronavirus outbreak, we will likely experience delays and/or realize
additional costs. We also rely on third parties for the manufacture of our product candidates for preclinical and clinical testing. Disruptions to the global supply
chain have impacted our and our third-party manufacturers’ ability to obtain raw materials or other products necessary to manufacture and distribute our product
candidates. As a result, our efforts to develop our products have been delayed, and recurrence of such disruptions could delay or disrupt our ability to obtain
regulatory  approvals  for,  and  to  commercialize,  our  product  candidates.  Finally,  we  have  incurred  considerable  expense  to  warehouse  sufficient  supplies  in
anticipation of future unexpected supply chain disruptions, and we may need to increase these expenses as we increase our cell processing.

The potential economic impact brought by and the duration of the pandemic may be difficult to assess or predict, however it has already caused, and is likely to
result in further, significant disruption of global financial markets, which may reduce our ability to access capital either at all or on favorable 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 ultimate impact of the current pandemic, or any other health epidemic, is highly uncertain and will depend on future developments that cannot be predicted
with confidence, such as the duration of the outbreak, the severity of COVID-19, and the effectiveness of actions to contain and treat for COVID-19. Although,
as  of  the  date  of  this Annual  Report  on  Form  10-K,  we  do  not  expect  any  material  impact  on  our  long-term  activity,  we  do  not  yet  know  the  full  extent  of
potential delays or impacts on our business, our clinical trials, our research programs, healthcare systems or the global economy as a whole, which could have a
material adverse effect on our business, financial condition and results of operations and cash flows. The Company has experienced some delays in clinical trial
accrual and in the availability and delivery of certain consumables and raw materials used in its laboratory and manufacturing operations due to the impact of
COVID-19 on the global supply chain.

The ability of the Company’s employees and consultants to work may be significantly impacted by the coronavirus.

The Company’s employees and consultants are being affected by the COVID-19 pandemic. The Company may need to enact further precautionary measures to
help minimize the risk of our employees being exposed to the coronavirus. COVID-19 may also compromise the ability of independent contractors who perform
consulting  services  for  us  to  deliver  services  or  deliverables  in  a  satisfactory  or  timely  manner.    Further,  our  management  team  is  focused  on  mitigating  the
adverse  effects  of  the  COVID-19  pandemic,  which  continues  to  require  an  investment  of  time  and  resources,  thereby  diverting  their  attention  from  other
priorities that existed prior to the outbreak of the pandemic. If these conditions worsen, or last for an extended period of time, the Company’s ability to manage
its business may be impaired, and operational risks, cybersecurity risks and other risks facing the Company even prior to the pandemic may be elevated.

Our growth is subject to economic and political conditions.

Our  business  is  affected  by  global  and  local  economic  and  political  conditions  as  well  as  the  state  of  the  financial  markets,  inflation,  recession,  financial
liquidity, currency volatility, growth, and policy initiatives. There can be no assurance that global economic conditions and financial markets will not worsen
and that we will not experience any adverse effects that may be material to our consolidated cash flows, results of operations, financial position or our ability to
access capital, such as the adverse effects resulting from a prolonged shutdown in government operations both in the United States and internationally. Political
changes, including war or other conflicts, some of which may be disruptive, could interfere with our supply chain, our customers and all of our activities in a
particular location.

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We may not be able to manage our business effectively if we are unable to attract and retain key personnel.

We may not be able to attract or retain qualified management and commercial, scientific and clinical personnel in the future due to the intense competition for
qualified personnel among biotechnology, pharmaceutical and other businesses. If we are not able to attract and retain necessary personnel to accomplish our
business objectives, we may experience constraints that will significantly impede the achievement of our development objectives, our ability to raise additional
capital and our ability to implement our business strategy.

Our  employees,  consultants,  or  third-party  partners  may  engage  in  misconduct  or  other  improper  activities,  including  but  not  necessarily  limited  to
noncompliance  with  regulatory  standards  and  requirements  or  internal  procedures,  policies  or  agreements  to  which  such  employees,  consultants  and
partners are subject, any of which could have a material adverse effect on our business.

We  are  exposed  to  the  risk  of  employee  fraud  or  other  misconduct.  Misconduct  by  employees,  consultants,  or  third-party  partners  could  include  intentional
failures to comply with FDA regulations, provide accurate information to the FDA, comply with cGMPs, comply with federal and state healthcare fraud and
abuse laws and regulations, report financial information or data accurately, comply with internal procedures, policies or agreements to which such employees,
consultants or partners are subject, or 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, consultant, or third-party 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, as well as civil and criminal liability. 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. 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 and results of operations, including the imposition of
significant fines or other civil and/or criminal sanctions.

We receive a large amount of proprietary information from potential or existing licensors of intellectual property and potential acquisition target companies, all
pursuant to confidentiality agreements. The confidentiality and proprietary invention assignment agreements that we have in place with each of our employees
and consultants prohibit the unauthorized disclosure of such information, but such employees or consultants may nonetheless disclose such information through
negligence  or  willful  misconduct. Any  such  unauthorized  disclosures  could  subject  us  to  monetary  damages  and/or  injunctive  or  equitable  relief.  The  notes,
analyses  and  memoranda  that  we  have  generated  based  on  such  information  are  also  valuable  to  our  businesses,  and  the  unauthorized  disclosure  or
misappropriation of such materials by our employees and consultants could significantly harm our strategic initiatives – especially if such disclosures are made
to our competitors.

We rely on information technology, and any internet or internal computer system failures, inadequacies, interruptions or compromises of our systems or the
security of confidential information could damage our reputation and harm our business.

Although a significant portion of our business is conducted using traditional methods of contact and communications such as face-to-face meetings, our business
is  increasingly  dependent  on  critical,  complex  and  interdependent  information  technology  systems,  including  internet-based  systems,  to  support  business
processes as well as internal and external communications. We could experience system failures and degradations in the future. We cannot assure you that we
will be able to prevent an extended and/or material system failure if any of the following or similar events occurs:

●

●

●

●

●

human error;

subsystem, component, or software failure;

a power or telecommunications failure;

hacker attacks, cyber-attacks, software viruses, security breaches, unauthorized access or intentional acts of vandalism; or

terrorist acts or war.

If any of the foregoing events were to occur, our business operations could be disrupted in ways that would require the incurrence of substantial expenditures to
remedy. Any system failure, accident or security breach that causes interruptions in our operations could result in a material disruption of our drug development
programs.  For  example,  the  loss  of  clinical  trial  data  from  completed  clinical  trials  for  one  or  more  of  our  product  conducts  could  result  in  delays  in  our
regulatory approval efforts and significantly increase our costs to recover or

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reproduce  the  data.  To  the  extent  that  any  disruption  or  security  breach  were  to  result  in  a  loss  of,  or  damage  to,  our  data  and  applications,  or
inappropriate/unauthorized disclosure of confidential or proprietary information (including trade secrets), we could incur liability and our business and financial
condition could be harmed.

The occurrence of a catastrophic disaster could damage our facilities beyond insurance limits, or we could lose key data which could cause us to curtail or
cease operations.

We are vulnerable to damage and/or loss of vital data from natural disasters, such as earthquakes, tornadoes, power loss, fire, health epidemics and pandemics,
floods and similar events, as well as from accidental loss or destruction. If any disaster were to occur, our ability to operate our businesses could be seriously
impaired.  We  have  property,  liability  and  business  interruption  insurance  that  may  not  be  adequate  to  cover  losses  resulting  from  disasters  or  other  similar
significant  business  interruptions,  and  we  do  not  plan  to  purchase  additional  insurance  to  cover  such  losses  due  to  the  cost  of  obtaining  such  coverage. Any
significant  losses  that  are  not  recoverable  under  our  insurance  policies  could  seriously  impair  our  business,  financial  condition  and  prospects. Any  of  the
aforementioned circumstances, including without limitation the resurgence of COVID-19 virus, may also impede our employees’ and consultants’ abilities to
provide  services  in-person  and/or  in  a  timely  manner;  hinder  our  ability  to  raise  funds  to  finance  our  operations  on  favorable  terms  or  at  all;  and  trigger
effectiveness of “force majeure” clauses under agreements with respect to which we receive goods and services, or under which we are obligated to achieve
developmental  milestones  on  certain  timeframes.  Disputes  with  third  parties  over  the  applicability  of  such  “force  majeure”  clauses,  or  the  enforceability  of
developmental milestones and related extension mechanisms in light of such business interruptions, may arise and may become expensive and time-consuming.

Our stock may be subject to substantial price and volume fluctuations due to a number of factors, many of which are beyond our control and may prevent
our stockholders from reselling our common stock at a profit.

The market prices for securities of biotechnology and pharmaceutical companies have historically been highly volatile, and the market has from time to time
experienced significant price and volume fluctuations that are unrelated to the operating performance of particular companies.

The market price of our common stock is likely to be highly volatile and may fluctuate substantially due to many factors, including:

●

announcements concerning the progress of our efforts to obtain regulatory approval for and commercialize our product candidates or any future product
candidate,  including  any  requests  we  receive  from  the  FDA  for  additional  studies  or  data  that  result  in  delays  in  obtaining  regulatory  approval  or
launching these product candidates, if approved;

● market conditions in the pharmaceutical and biotechnology sectors or the economy as a whole;

●

●

●

●

●

●

●

●

●

price and volume fluctuations in the overall stock market;

the failure of one or more of our product candidates or any future product candidate, if approved, to achieve commercial success;

announcements of the introduction of new products by us or our competitors;

developments concerning product development results or intellectual property rights of others;

litigation or public concern about the safety of our potential products;

actual fluctuations in our quarterly operating results, and concerns by investors that such fluctuations may occur in the future;

deviations in our operating results from the estimates of securities analysts or other analyst comments;

additions or departures of key personnel;

health  care  reform  legislation,  including  measures  directed  at  controlling  the  pricing  of  pharmaceutical  products,  and  third-party  coverage  and
reimbursement policies;

●

developments concerning current or future strategic collaborations; and

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●

discussion of us or our stock price by the financial and scientific press and in online investor communities.

We have received notice from the Nasdaq Stock Market of non-compliance with its minimum bid price rules.

On May 24, 2022, we received written notification (the “Notice Letter”) from the Nasdaq Stock Market (“Nasdaq”) indicating that we were not in compliance
with Nasdaq Listing Rule 5450(a)(1), as the closing bid price for our Common Stock was below the $1.00 per share requirement for the previous 30 consecutive
business days. The Notice Letter stated that we had 180 calendar days, or until November 21, 2022 (the “Initial Compliance Period”), to regain compliance with
the minimum bid price requirement. On November 22, 2022, we were granted an additional 180 calendar days, or until May 24, 2023 (“Extended Compliance
Period”), to regain compliance with the minimum bid price requirement. In accordance with Nasdaq Listing Rule 5810(c)(3)(A), we can regain compliance if the
closing  bid  price  of  our  Common  Stock  is  at  least  $1.00  for  a  minimum  of  10  consecutive  business  days. Although  we  have  taken  steps  toward  effecting  a
reverse  stock  split  in  order  to  regain  compliance  with  the  minimum  bid  price  requirement,  and  we  expect  to  complete  the  reverse  stock  split  and  regain
compliance within the extended compliance period, there can be no assurance that such transaction will be completed, or if completed, will be successful in
regaining compliance with the minimum bid price requirement.

In the event that we do not regain compliance with Listing Rule 5450(a)(1) prior to the expiration of the Extended Compliance Period, we will receive written
notification that our securities are subject to delisting. At that time, we may appeal the delisting determination to a hearings panel pursuant to the procedures set
forth in the applicable Nasdaq Listing Rules. A delisting of our Common Stock would have an adverse effect on the market liquidity of our Common Stock and,
as a result, the market price for our Common Stock could become more volatile. Further, a delisting could also make it more difficult for us to raise additional
capital.

We may become involved in securities class action litigation that could divert management’s attention and harm our business.

The stock markets have from time to time experienced significant price and volume fluctuations that have affected the market prices for the common stock of
biotechnology and pharmaceutical companies. These broad market fluctuations may cause the market price of our stock to decline. In the past, securities class
action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us because
biotechnology and biopharmaceutical companies have experienced significant stock price volatility in recent years. We may become involved in this type of
litigation in the future. Litigation often is expensive and diverts management’s attention and resources, which could adversely affect our business.

Item 1B.       Unresolved Staff Comments

None.

Item 2.        Properties

Our corporate and executive office is located at 377 Plantation Street, Worcester, MA 01605.

On October 27, 2017, we entered into a lease agreement with WCS - 377 Plantation Street, Inc., a Massachusetts nonprofit corporation (“Landlord”). Pursuant to
the  terms  of  the  lease  agreement,  we  agreed  to  lease  27,043  sf  from  the  Landlord,  located  at  377  Plantation  Street  in  Worcester,  MA  (the  “Plantation  Street
Facility”),  through  November  2026,  subject  to  additional  extensions  at  our  option.  Base  rent,  net  of  abatements  of  $0.6  million  over  the  lease  term,  totals
approximately $3.6 million, on a triple-net basis.

The Plantation Street Facility became operational for the production of personalized CAR T and gene therapies in 2018.

On June 14, 2022, the Company entered into a sublease agreement with The Paul Revere Life Insurance Company. Pursuant to the terms of the sublease lease
agreement, the Company agreed to lease 26,503 square feet, located at 1 Mercantile Street, Worcester, MA (the “Mercantile Street Facility”), through January
2030. Base rent, net of abatements of $1.2 million, totals approximately $3.4 million.

Item 3.      Legal Proceedings

We are not involved in any legal proceedings that we believe could have a material adverse effect on our financial position or results of operations. There is no
action, suit, proceeding, inquiry or investigation before or by any court, public board, government agency, self-regulatory organization or body pending or, to the
knowledge of our executive officers, threatened against or affecting our company or our officers or directors in their capacities as such.

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Item 4.        Mine Safety Disclosures

Not applicable

Item 5.      Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Market information

PART II

On November 22, 2022, our common stock listing transferred to the NASDAQ Capital Market tier and continues to be traded under the symbol “MBIO.” Our
common stock had been quoted on the NASDAQ Global Market since August 22, 2017, under the symbol “MBIO.” Prior to this there was no public market for
our common stock.

Securities Authorized for Issuance Under Equity Compensation Plans

On November 30, 2017, July 30, 2021, and July 15, 2022, we filed a registration statement on Form S-8 under the Securities Act registering the common stock
issued, issuable or reserved for issuance under our 2016 Plan. That registration statement became effective immediately upon filing, and shares covered by the
registration statement are eligible for sale in the public markets, subject to grant of the underlying awards, vesting provisions and Rule 144 limitations applicable
to our affiliates.

Our Board of Directors approved, and our stockholders subsequently approved, a reverse stock split of our Common Stock. On March 15, 2023, the Board of
Directors set the reverse stock split ratio at 15-for-1. We have filed a Definitive Information Statement on Schedule 14C in connection with the reverse stock
split,  and  once  the  applicable  waiting  periods  under  SEC  and  Nasdaq  rules  have  expired,  we  plan  to  file  a  Certificate  of Amendment  to  our Amended  and
Restated Certificate of Incorporation, as amended, in order to give effect to the reverse stock split.

The information required by Item 5 of Form 10-K addressing equity compensation plans is incorporated herein by reference to “Item 12, Security Ownership of
Certain Beneficial Owners of Management and Related Stockholder Matters.”
Holders of Record

As of December 31, 2022, there were approximately 75 holders of record of our common stock and one holder of record for our Class A common stock. The
actual number of stockholders of our common shares 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. This number of holders of record also does not include stockholders whose shares may be
held in trust by other entities.

Dividends

We have never paid or declared any cash dividends on our common stock, and we do not anticipate paying any cash dividends on our common stock in the
foreseeable  future.  We  intend  to  retain  all  available  funds  and  any  future  earnings  to  fund  the  development  and  expansion  of  our  business.  Any  future
determination to pay dividends will be at the discretion of our board of directors and will depend upon a number of factors, including our results of operations,
financial condition, future prospects, contractual restrictions, restrictions imposed by applicable law and other factors our board of directors deems relevant.

The Term Loan provides that, so long as any obligation thereunder remains unpaid, or any lender thereunder has any obligation to make any loan thereunder, the
Company shall not pay any dividends or make any distribution or payment in respect of its equity interests, subject to limited exceptions.

Recent Sales of Unregistered Securities

None.

Issuer Purchases of Equity Securities

None.

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Item 6.       Reserved

Item 7.       Management’s Discussion and Analysis of the Results of Operations

Statements in the following discussion and throughout this report that are not historical in nature are “forward-looking statements.” You can identify forward-
looking  statements  by  the  use  of  words  such  as  “expect,”  “anticipate,”  “estimate,”  “may,”  “will,”  “should,”  “intend,”  “believe,”  and  similar  expressions.
Although we believe the expectations reflected in these forward-looking statements are reasonable, such statements are inherently subject to risk and we can
give no assurances that our expectations will prove to be correct. Actual results could differ from those described in this report because of numerous factors,
many of which are beyond our control. These factors include, without limitation, those described under Item 1A “Risk Factors.” We undertake no obligation to
update  these  forward-looking  statements  to  reflect  events  or  circumstances  after  the  date  of  this  report  or  to  reflect  actual  outcomes.  Please  see  “Forward-
Looking Statements” at the beginning of this Form 10-K.

The following discussion of our financial condition and results of operations should be read in conjunction with our financial statements and the related notes
thereto and other financial information appearing elsewhere in this Form 10-K. We undertake no obligation to update any forward-looking statements in the
discussion of our financial condition and results of operations to reflect events or circumstances after the date of this report or to reflect actual outcomes.

Overview

Mustang is a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell and gene therapies into potential cures for
hematologic cancers, solid tumors and rare genetic diseases. We aim to acquire rights to these technologies by licensing or otherwise acquiring an ownership
interest in the technologies, funding their research and development and eventually either out-licensing or bringing the technologies to market.

Our pipeline is currently focused in three core areas: CAR T therapies for hematologic malignancies, CAR T therapies for solid tumors and gene therapies for
rare genetic disorders. For each therapy we have partnered with world class research institutions. For our CAR T therapies we have partnered with COH, Fred
Hutch, Nationwide and Mayo Clinic. For our gene therapies, we have partnered with St. Jude in the development of a first-in-class ex vivo lentiviral treatment of
XSCID and with LUMC in the development of a first-in-class ex vivo lentiviral treatment of RAG1-SCID.

The Company expects to incur substantial expenses for the foreseeable future relating to research, development and commercialization of its potential products.
However, there can be no assurance that the Company will be successful in securing additional resources when needed, on terms acceptable to the Company, if
at all. Therefore, there exists substantial doubt about the Company’s ability to continue as a going concern. The consolidated financial statements do not include
any adjustments related to the recoverability of assets that might be necessary despite this uncertainty.

CAR T Therapies

Our  pipeline  of  CAR  T  therapies  is  being  developed  under  exclusive  licenses  from  several  world  class  research  institutions.  Our  strategy  is  to  license  these
technologies, support preclinical and clinical research activities by our academic partners and transfer the underlying technology to our cell processing facility
located in Worcester, Massachusetts, in order to conduct our own clinical trials.

We are developing CAR T therapies for hematologic malignancies in partnership with COH targeting CD123 (MB-102) and CS1 (MB-104) and with Fred Hutch
targeting CD20 (MB-106). Phase 1 clinical trials sponsored by COH for MB-102 and MB-104 and by Fred Hutch for MB-106 are underway. In the third quarter
of 2019 the FDA approved our IND application to initiate a multi-center Phase 1/2 clinical trial of MB-102, and our clinical trial began enrollment in 2020 for
the treatment of patients with blastic plasmacytoid dendritic cell neoplasm (“BPDCN”). In December 2022, we announced that the safety review team (SRT),
after thoroughly reviewing the safety data from Dose Level 1 (100 x 106 CAR T cells), unanimously recommended dose escalation to Dose Level 2 (300 x 106
CAR T cells). We anticipate initiation of the Does Level 2 cohort in 2023.

In May 2021, we announced that the FDA had approved our IND application allowing for initiation of a multi-center Phase 1/2 clinical study of MB-106 in
patients with relapsed or refractory B cell NHL or CLL (Clinicaltrials.gov Identifier: NCT05360238).

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We plan to file an IND for a multicenter Phase 1/2 trial for MB-104 for the treatment of patients with multiple myeloma once COH has established a safe and
effective dose.

We are also developing CAR T therapies for solid tumors in partnership with COH targeting IL13Rα2 (MB-101), HER2 (MB-103) and PSCA (MB-105). In
addition, we have partnered with Nationwide for the C134 oncolytic virus (MB-108) in order to enhance the activity of MB-101 for the treatment of patients with
glioblastoma (“GBM”). Phase 1 clinical trials sponsored by COH for MB-101, MB-103 and MB-105 are underway. A Phase 1 clinical trial sponsored by UAB
for MB-108 began during the third quarter of 2019. In the first half of 2023, we plan to file an IND for the combination of MB-101 and MB-108 – which is
referred to as MB-109 – for the treatment of patients with relapsed or refractory GBM and anaplastic astrocytoma. We also plan to file INDs and initiate our own
clinical trials for  MB-103  for  the  treatment  of  patients  with  metastatic  breast  cancer  to  brain  and  for  MB-105  for  the  treatment  of  patients  with  prostate  and
pancreatic cancer, once COH has established a safe and effective dose for each therapy. The Company is also collaborating with the Mayo Clinic to develop a
novel technology that may be able to transform the administration of CAR T therapies and potentially be used as an off-the-shelf therapy. Mustang plans to file
an IND application for a multicenter Phase 1 clinical trial once a lead construct has been identified.

Gene Therapies

In partnership with St. Jude, our XSCID gene therapy programs (MB-107 and MB-207) are being conducted under an exclusive license to develop a potentially
curative treatment for XSCID, a rare genetic immune system condition in which affected patients do not live beyond infancy without treatment. This first-in-
class ex vivo lentiviral gene therapy has been evaluated in two Phase 1/2 clinical trials involving two different autologous cell products: an ongoing multicenter
trial of the MB-107 product in newly diagnosed infants sponsored by St. Jude and a single-center trial of the MB-207 product in previously transplanted patients
sponsored by the NIH. In January 2021 we received approval to proceed with our IND application with the FDA to initiate a pivotal non-randomized multicenter
Phase  2  clinical  trial  of  MB-107  in  newly  diagnosed  infants  with  XSCID  who  are  under  the  age  of  two.  We  expect  to  enroll  the  first  patient  in  a  pivotal
multicenter Phase 2 clinical trial in 2023. Our IND for MB-207 was submitted to the FDA in December 2021. In January 2022, the FDA issued a clinical hold,
pending CMC data.  In order to lift this clinical hold and receive a safe-to-proceed from the FDA for the IND, we believe the most critical activities will be to (1)
perform process validation manufacturing runs using healthy donor material and (2) ensure qualification of all assays related to the product release. Following
completion of these activities and the earliest release of the clinical hold, we expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial 2023.

Recent Events

MB-102 (CD123 CAR T Cell Program for BPDCN, AML and High-Risk MDS)

In December 2022, we announced that the safety review team (SRT), after thoroughly reviewing the safety data from Dose Level 1 (100 x 106  CAR  T  cells),
unanimously recommended dose escalation to Dose Level 2 (300 x 106 CAR T cells). The Company anticipates initiation of the Dose Level 2 cohort in 2023.

MB-106 (CD20-targeted CAR T for Non-Hodgkin Lymphoma and Chronic Lymphocytic Leukemia)

In May 2021, we announced that the FDA had approved our IND application allowing for initiation of a multi-center Phase 1/2 clinical study of MB-106 in
patients with relapsed or refractory B cell NHL or CLL (Clinicaltrials.gov Identifier: NCT05360238). The phase 1 portion of the trial will enroll patients in 3
separate arms, with dose escalation planned to establish a recommended phase 2 dose for each arm:

● Arm 1: Aggressive non-Hodgkin lymphoma, with a starting dose of 1 x 106 CAR T cells/kg
● Arm 2: Indolent non-Hodgkin lymphoma, with a starting dose of 3.3 x 106 CAR T cells/kg
● Arm 3: Chronic lymphocytic leukemia/small cell lymphoma, with a starting dose of 1 x 106 CAR T cells/kg

The  FDA  deferred  approval  of  the  phase  2  portion  of  this  trial  pending  review  of  the  results  of  each  of  the  3  phase  1  arms.  Initially  we  are  considering
conducting non-randomized phase 2 registration trials in each of the following indications:
1. Diffuse large B cell lymphoma relapsed from CD19-directed CAR T therapy
2. Relapsed/refractory Waldenstrom macroglobulinemia
3. Relapsed/refractory chronic lymphocytic leukemia/small cell lymphoma

In April  2022,  we  announced  that  interim  Phase  1/2  data  on  MB-106  were  presented  at  the  2022  Tandem  Meetings  |  Transplantation  &  Cellular  Therapy
Meetings  of  the  American  Society  of  Transplantation  and  Cellular  Therapy  and  Center  for  International  Blood  &  Marrow  Transplant  Research.  Data
demonstrated high efficacy and a very favorable safety profile in all patients (n=25). Five dose levels were used

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during  the  study,  and  complete  responses  were  observed  at  all  dose  levels.  Durable  responses  were  observed  in  a  wide  range  of  hematologic  malignancies
including follicular lymphoma (“FL”), CLL, diffuse large B-cell lymphoma (“DLBCL”) and Waldenstrom macroglobulinemia (“WM”). An ORR of 96% and a
complete response (“CR”) rate of 72% were observed in all patients across all dose levels.

Also in April 2022, MB-106 data focused on CLL were presented at the 4th International Workshop on CAR-T and Immunotherapies.

In June 2022, we announced that MB-106 data were presented in an oral session at the European Hematology Association 2022 Hybrid Congress. Dr. Mazyar
Shadman of Fred Hutch presented updated interim data from the ongoing Phase 1/2 clinical trial for B-NHL and CLL. Data presented include a 94% ORR and
78% CR rate in patients with FL. Overall, for the 26 patients treated on the trial, there was a 96% ORR and 73% CR, including complete responses in both
DLBCL patients, both WM patients, and both patients previously treated with CD19-targeted CAR-T therapy (1 DLBCL patient and 1 FL patient).

Also in June 2022, we announced that the FDA granted Orphan Drug Designation to MB-106 for the treatment of CD20+ Waldenstrom macroglobulinemia.

In October 2022, we announced that the first patient was treated in Mustang’s multicenter, open-label, non-randomized Phase 1/2 clinical trial evaluating the
safety and efficacy of MB-106.

Also in October 2022, the Company provided an update on the ongoing Phase 1/2 investigator-sponsored clinical trial at Fred Hutch.  Interim Data from 28
patients treated at Fred Hutch, all with the optimized manufacturing process, continue to support MB-106 as a viable CAR-T cell therapy for B-NHLs and CLL.
As of September 2022, the interim data show:

● An overall response rate of 96% and complete response (“CR”) rate of 75% in a wide range of hematologic malignancies including follicular lymphoma

●

(“FL”), CLL, diffuse large B-cell lymphoma, and Waldenstrom macroglobulinemia.
Twelve patients have experienced CR for more than 12 months (10 ongoing); four patients have experienced CR for more than two years, and the
longest patient with CR is at 33 months.
Six patients with partial response (“PR”) at their initial 28-day assessments improved to CR, and all remain in ongoing CR.

●
● All three patients previously treated with CD19 CAR-T cell therapy have responded to treatment with MB-106.
● A favorable safety profile for MB-106 as an outpatient therapy remains with no cytokine release syndrome (CRS) or immune effector cell-associated

neurotoxicity syndrome (ICANS) ≥ Grade 3.

● None of the FL patients experienced ICANS of any Grade.

In December 2022, we announced that six patients had been enrolled in Mustang’s multicenter Phase 1/2 clinical trial, with five patients infused at the starting
dose levels of their respective protocol arms. We have since treated the first WM in the indolent lymphoma arm of the trial, and we expect to provide first safety
and efficacy data from that arm in the second quarter of 2023, with a more substantial data set from all 3 arms in the fourth quarter of 2023. Finally, we
anticipate that the indication for the first pivotal Phase 2 trial will be relapsed/refractory WM, with the first patient treated on that trial in the first quarter of
2024.

In Vivo CAR T Platform Technology

In December 2022 we announced that published proof-of-concept data from murine tumor model studies are anticipated in 2023.

MB-107 and MB-207 (Ex vivo Lentiviral Therapy for X-linked Severe Combined Immunodeficiency (XSCID))

Interim  Phase  1/2  data  on  treatment  of  newly  diagnosed  infants  under  the  age  of  two  with  the  same  LV  vector  used  in  MB-107  were  updated  at  an  oral
presentation at the American Society of Gene & Cell Therapy (“ASGCT”) 25 th Annual Meeting held from May 16-19, 2022. The data included 23 infants with
XSCID treated with the LV vector at a median age of 3 months (range: 2 months to 14 months) with a median follow-up of 2.4 years (range: 1.4 months to 5.4
years), making it the largest known cohort of infants treated with LV gene therapy with the longest follow-up. Transduced autologous bone marrow CD34+ cells
were generated for all patients with a median vector copy number (VCN) of 0.81/cell (range: 0.16-1.81), and a median CD34+ cell dose of 9.61x106/kg (range
4.40-18.95).  Prior  to  the  infusion  of  cells,  patients  received  busulfan  targeted  to  a  cumulative  area-under-the-curve  (cAUC)  of  22  mg*hr/L.  Severe  adverse
events occurred in three patients (two patients with pancytopenia and hemolytic anemia, and one patient with delayed neutrophil engraftment, and all resolved.

Seventeen  of  18  patients  with  a  follow-up  of  >  6  months  achieved  robust  immune  reconstitution  [median  CD3+  2,545/µL,  CD4+  1,568/µL,
CD4+/CCR7+/CD45R0-  1,416/µL].    In  these  17  patients,  T  cells  matured  appropriately  as  assessed  by  normal  T  cell  receptor  excision  circles  (TRECs)  and
TCRvβ repertoire diversity and were functional as judged by phytohemagglutinin activation (“PHA”).   All were alive with

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stable  vector  marking  in  all  cell  lineages.    In  addition,  15  patients  had    discontinued  intravenous  immunoglobulin,  and  12  patients  had    been  successfully
immunized.  No evidence of clonal expansion or malignant transformation was observed.

The MB-107 timeline has been extended due to unanticipated issues related to the materials used in manufacturing. These issues were communicated to the FDA
and the Company received a written response on August 26, 2022.  The FDA response provided additional direction enabling us to continue to work effectively
with our outside suppliers. We are working towards enrolling the first patient in a pivotal multicenter Phase 2 clinical trial under our IND in 2023.

As a result of the study stopping rules, the NIH single-center trial of the MB-207 product in previously transplanted patients was suspended in 2022 due to the
presence of clonal expansion in the myeloid lineage in 10% of the treated patients, although to date there have been no observations of insertional mutagenesis or
malignancies.  All patients continue to be followed and remain clinically stable with  no  significant  hematological  anomalies.  Upon  review  of  these  data,  the
FDA agreed that the risk-benefit ratio of both MB-107 and MB-207 remains favorable to support moving forward with Mustang-sponsored multicenter clinical
trials once Mustang has appropriately addressed other items flagged by the Agency.  

The IND for MB-207 was submitted to the FDA in December 2021.  In January 2022, the FDA issued a clinical hold, pending additional CMC data. In order to
lift  this  clinical  hold  and  receive  an  FDA  safe-to-procced  for  the  IND,  we  believe  the  most  critical  activities  will  be  to  (1)  perform  process  validation
manufacturing runs using healthy donor material and (2) ensure qualification of all assays related to the product release. Following completion of these activities
and the earliest release of the clinical hold by FDA, we expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial in 2023.

LUMC License

On  July  27,  2022,  the  Company  announced  that  the  first  patient  successfully  received  LV-RAG1 ex vivo  lentiviral  gene  therapy  to  treat  RAG1-SCID,  in  an
ongoing Phase 1/2 multicenter clinical trial taking place in Europe at LUMC. The patient was administered LV-RAG1 without any complications. LV-RAG1
allowed the patient’s body to create a functioning immune system, and he responded well to the standard vaccinations for newborns. The same lentiviral vector
drug substance produced by LUMC will be used to transduce patients’ cells to create the MB-110 drug product produced at Mustang Bio’s Worcester, MA, cell
processing facility for further clinical development and to facilitate eventual commercial launch of the product.

Registration Statements

On  October  23,  2020,  the  Company  filed  a  shelf  registration  statement  No.  333-249657  on  Form  S-3  (the  “2020  S-3”),  which  was  declared  effective  on
December  4,  2020.  Under  the  2020  S-3,  the  Company  may  sell  up  to  a  total  of  $100.0  million  of  its  securities. As  of  December  31,  2022,  approximately
$8.0 million of the 2020 S-3 remained available for sales of securities.

On April 23, 2021, the Company filed a shelf registration statement No. 333-255476 on Form S-3 (the “2021 S-3”), which was declared effective on May 24,
2021. Under the 2021 S-3, the Company may sell up to a total of $200.0 million of its securities. As of December 31, 2022, there have been no sales of securities
under the 2021 S-3.

The amount of securities we are able to sell pursuant to the registration statements on Form S-3 is limited. See “Risk Factors” and “Management’s Discussion
and Analysis of Financial Condition and Results of Operations – Liquidity and Capital Resources.”

Term Loan

On  March  4,  2022  (the  “Closing  Date”),  the  Company  entered  into  a  $75.0  million  long-term  debt  facility  with  Runway  Growth  Finance  Corp.  (the  “Term
Loan”).  Under  the  Term  Loan,  $30.0  million  of  the  $75.0  million  loan  was  funded  on  the  Closing  Date,  with  the  remaining  $45.0  million  fundable  if  the
Company achieves certain predetermined milestones.

The Term Loan matures on April 15, 2027 (the “Maturity Date”). As of March 15, 2022, the Company began making monthly payments of interest only until
April 1, 2024 (the “Amortization Date”). The Amortization Date may be extended to April 1, 2025, if the Company achieves certain predetermined milestones
based  on  equity  raises  and  the  initiation  of  certain  clinical  trials.  After  that,  the  Company  will  make  monthly  payments  of  interest  and  principal.  If  the
Amortization Date is extended to April 1, 2025, the monthly payments will be recalculated in equal amounts according to the remaining number of payment
dates through the Maturity Date. All unpaid outstanding principal and accrued and unpaid interest will be due and payable in full on the Maturity Date.

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The  Term  Loan  accrues  interest  at  a  variable  annual  rate  equal  to  8.75%  plus  the  greater  of  (i)  0.50%  and  (ii)  the  three  month  LIBOR  Rate  for  U.S.  dollar
deposits or the rate otherwise reasonably determined by the Lender to be the rate at which U.S. dollar deposits with a term of three months would be offered by
banks in London, England to major banks in the London or other offshore interbank market  (the “Applicable Rate”); provided that the Applicable Rate will not
be less than 9.25%. On December 7, 2022, the Company entered into the First Amendment (the “First Amendment”) to the Loan Agreement by and between the
Company  and  Runway.  The  First Amendment  amended  certain  definitions  and  other  provisions  of  the  Loan Agreement  to  replace  LIBOR-based  benchmark
rates  applicable  to  loans  outstanding  under  the  Loan Agreement  with  SOFR-based  rates,  subject  to  adjustments  as  specified  in  the  First Amendment.  The
Applicable Rate at December 31, 2022, was 13.40%. For the year ended December 31, 2022, the Company made interest payments of $2.7 million recorded in
interest expense in the Statements of Operations.

Pursuant  to  the  terms  of  the  Term  Loan  on  the  Closing  Date  the  Company  paid  the  Lender  upfront  fees  out  of  proceeds  of  $0.4  million  consisting  of  a  1%
commitment fee and a deposit of $75,000.  In addition, the Company paid other cash fees directly to third parties comprising of an advisory fee and legal fees
totaling $2.3 million.

Also, in connection with the Term Loan, on March 4, 2022, the Company issued a warrant to the Lender to purchase 748,036 shares of the Company’s common
stock with an exercise price of $0.8021 (the “Warrant”) via a warrant agreement (the “Warrant Agreement”). The Warrant is exercisable for ten years from the
date of issuance. The Lender may exercise the Warrant with cash or through a net issuance conversion. The shares of the Company’s common stock will be
registered at the Company’s first opportunity after the date of the exercise of the Warrant. In addition, the provisions of the Warrant Agreement provide for
additional warrants to be issued upon funding of the term loan tranches. The fair value of the warrant at the grant date was determined utilizing a Black Scholes
Model  with  the  following  assumptions:  risk  free  rate  of  return  1.74%,  volatility  of  57.3%,  10-year  life  yielding  a  value  of  approximately  $0.4  million  as  of
March 4, 2022.  The fair value of the warrant was also recorded in debt discount and will be amortized over the life of the Term Loan.

At-the-Market Offering

In July 2018, the Company entered into an At-the-Market Issuance Sales Agreement (the “Mustang ATM”) with B. Riley Securities, Inc. (formerly B. Riley
FBR, Inc.), Cantor Fitzgerald & Co., National Securities Corporation (now B. Riley FBR, Inc.), and Oppenheimer & Co. Inc. (each an “Agent” and collectively,
the “Agents”), relating to the sale of shares of common stock pursuant to the 2020 S-3. Under the Mustang ATM, the Company pays the Agents a commission
rate of up to 3.0% of the gross proceeds from the sale of any shares of common stock. On December 31, 2020, the Mustang ATM was amended to add H.C.
Wainwright & Co., LLC as an Agent.

During the year ended December 31, 2022, the Company issued approximately 7.9 million shares of common stock at an average price of $0.84 per share for
gross proceeds of $6.6 million under the ATM Agreement. In connection with these sales, we paid aggregate fees of approximately $0.1 million for net proceeds
of approximately $6.5 million.

During the year ended December 31, 2021, the Company issued approximately 19.4 million shares of common stock at an average price of $3.70 per share for
gross  proceeds  of  $71.9  million  under  the ATM Agreement.  In  connection  with  these  sales,  we  paid  aggregate  fees  of  approximately  $1.3  million  for  net
proceeds of approximately $70.6 million.

Pursuant to the Founders Agreement, the Company issued 196,952 shares of common stock to Fortress at a weighted average price of $0.84 per share for the
year ended December 31, 2022, and recorded zero shares issuable to Fortress in connection with the shares issued under the Mustang ATM. Pursuant to the
Founders Agreement, Mustang issued 576,157 shares of common stock to Fortress at a weighted average price of $3.70 per share for the year ended December
31, 2021, in connection with the shares issued under the Mustang ATM.

The amount of securities we are able to sell pursuant to the registration statements on Form S-3 is limited. See “Risk Factors” and “Management’s Discussion
and Analysis of Financial Condition and Results of Operations – Liquidity and Capital Resources.”

Authorized Shares

On  June  21,  2022,  the  stockholders  of  the  Company  voted  at  the  2022  Annual  Meeting  to  approve  an  amendment  to  Mustang’s  Amended  and  Restated
Certificate  of  Incorporation  to  increase  the  number  of  shares  of  common  stock  authorized  for  issuance  by  50  million  shares,  bringing  the  total  number  of
authorized shares of common stock to 200 million shares.

We are a majority-controlled subsidiary of Fortress. As a “Controlled Company” we rely on the exemption provided by Nasdaq Listing Rule 5615(c)(2), which
permits us to maintain less than a majority of independent directors on our board.

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Critical Accounting Policies and Use of Estimates

The  Company’s  financial  statements  include  certain  amounts  that  are  based  on  management’s  best  estimates  and  judgments.  The  Company’s  significant
estimates include, but are not limited to, useful lives assigned to long-lived assets and amortizable intangible assets, fair value of stock options and warrants,
stock-based compensation, accrued expenses, provisions for income taxes and contingencies. Due to the uncertainty inherent in such estimates, actual results
may  differ  from  these  estimates.  Our  estimates  are  based  on  our  historical  experience  and  on  various  other  factors  that  we  believe  are  reasonable  under  the
circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other
sources.

Actual results may differ from these estimates under different assumptions or conditions. We believe that the accounting policies discussed below are critical to
understanding our historical and future performance, as these policies relate to the more significant areas involving management’s judgments and estimates.

While our significant accounting policies are described in the notes to our financial statements included elsewhere in this Report, we believe that the following
critical accounting policies are most important to understanding and evaluating our reported financial results.

Research and Development

Research  and  development  costs  are  expensed  as  incurred. Advance  payments  for  goods  and  services  that  will  be  used  in  future  research  and  development
activities  are  expensed  when  the  activity  has  been  performed  or  when  the  goods  have  been  received  rather  than  when  the  payment  is  made.  Upfront  and
milestone payments due to third parties that perform research and development services on the Company’s behalf will be expensed as services are rendered or
when the milestone is achieved.

Research  and  development  costs  primarily  consist  of  personnel  related  expenses,  including  salaries,  benefits,  travel,  and  other  related  expenses,  stock-based
compensation,  payments  made  to  third  parties  for  license  and  milestone  costs  related  to  in-licensed  products  and  technology,  payments  made  to  third  party
contract  research  organizations  for  preclinical  and  clinical  studies,  investigative  sites  for  clinical  trials,  consultants,  the  cost  of  acquiring  and  manufacturing
clinical trial materials, and costs associated with regulatory filings, laboratory costs and other supplies.

In  accordance  with ASC  730  10  25  1, Research  and  Development,  costs  incurred  in  obtaining  technology  licenses  are  charged  to  research  and  development
expense if the technology licensed has not reached commercial feasibility and has no alternative future use. In each case, we evaluate if the license agreement
results  in  the  acquisition  of  an  asset  or  a  business.  Such  licenses  purchased  by  the  Company  require  substantial  completion  of  research  and  development,
regulatory and marketing approval efforts in order to reach commercial feasibility and has no alternative future use. Accordingly, the total purchase price for the
licenses acquired during the period was reflected as research and development - licenses acquired on the Statements of Operations for the years ended December
31, 2022 and 2021.

Accrued Research and Development Expense

We  record  accruals  for  estimated  costs  of  research,  preclinical,  clinical  and  manufacturing  development  within  accrued  expenses  which  are  significant
components of research and development expenses. A substantial portion of our ongoing research and development activities is conducted by third-party service
providers. We accrue the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective
agreements.  We  determine  the  estimated  costs  through  discussions  with  internal  personnel  and  external  service  providers  as  to  the  progress,  or  stage  of
completion or actual timeline (start-date and end-date) of the services and the agreed-upon fees to be paid for such services. Payments made to third parties under
these arrangements in advance of the performance of the related services are recorded as prepaid expenses until the services are rendered.

If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust accrued expenses or prepaid expenses accordingly,
which  impact  research  and  development  expenses. Although  we  do  not  expect  our  estimates  to  be  materially  different  from  amounts  actually  incurred,  our
understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting
amounts that are too high or too low in any particular period.

Fair Value Measurement

The Company follows accounting guidance on fair value measurements for financial assets and liabilities measured at fair value on a recurring basis. Under the
accounting guidance, fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an
orderly transaction between market participants at the measurement date. As such, fair value is a

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market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability.

The accounting guidance requires fair value measurements be classified and disclosed in one of the following three categories:

Level 1:    Quoted prices in active markets for identical assets or liabilities.
Level 2:    Observable inputs other than Level 1 prices for similar assets or liabilities that are directly or indirectly observable in the marketplace.
Level 3:    Unobservable inputs which are supported by little or no market activity and that are financial instruments whose values are determined using
pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value
requires significant judgment or estimation.

The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.
Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The
Company’s  assessment  of  the  significance  of  a  particular  input  to  the  fair  value  measurement  in  its  entirety  requires  management  to  make  judgments  and
consider factors specific to the asset or liability.

Certain of the Company’s financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate their fair value
due to their liquid or short-term nature, such as accounts payable, accrued expenses and other current liabilities.

Stock-Based Compensation

The  Company  expenses  stock-based  compensation  to  employees  and  non-employees  over  the  requisite  service  period  based  on  the  estimated  grant-date  fair
value of the awards and forfeitures, which are recorded upon occurrence. The Company estimates the fair value of stock option grants using the Black-Scholes
option  pricing  model.  The  assumptions  used  in  calculating  the  fair  value  of  stock-based  awards  represent  management’s  best  estimates  and  involve  inherent
uncertainties and the application of management’s judgment.  

We  will  continue  to  use  judgment  in  evaluating  the  expected  volatility,  expected  terms  and  interest  rates  utilized  for  our  stock-based  compensation  expense
calculations  on  a  prospective  basis.    The  assumptions  underlying  these  valuations  represent  our  management’s  best  estimate,  which  involve  inherent
uncertainties and the application of management judgment. As a result, if factors or expected outcomes change and we use significantly different assumptions or
estimates,  our  stock-based  compensation  expense  could  be  materially  different.  We  expect  to  continue  to  grant  options  and  other  stock-based  awards  in  the
future, and to the extent that we do, our stock-based compensation expense recognized in future periods will likely increase.

Income Taxes

The Company accounts for income taxes under ASC 740, Income Taxes (“ASC 740”). ASC 740 requires the recognition of deferred tax assets and liabilities for
both the expected impact of differences between the financial statement and tax basis of assets and liabilities and for the expected future tax benefit to be derived
from tax loss and tax credit carry forwards. ASC 740 additionally requires a valuation allowance to be established when it is more likely than not that all or a
portion of deferred tax assets will not be realized.  Judgments concerning the recognition and measurement of a tax benefit might change as new information
becomes available. Our unrecognized tax benefits, if recognized, would not have an impact on our effective tax rate assuming we continue to maintain a full
valuation allowance position. We do not expect our unrecognized tax benefits to change significantly over the next 12 months.

ASC 740 also clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements and prescribes a recognition threshold
and measurement process for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. For those benefits
to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. ASC 740 also provides guidance on de-
recognition,  classification,  interest  and  penalties,  accounting  in  interim  period,  disclosure  and  transition.  Based  on  the  Company’s  evaluation,  it  has  been
concluded that there are no significant uncertain tax positions requiring recognition in the Company’s financial statements. As of December 31, 2022, the earliest
federal tax year open for the assessment of income taxes under the applicable statutes of limitations is its 2019 tax year. The Company believes that its income
tax positions and deductions would be sustained on audit and does not anticipate any adjustments that would result in a material change to its financial position.

The Company’s policy for recording interest and penalties associated with audits is to record such expense as a component of income tax expense. There were no
amounts accrued for penalties or interest as of or during the years ended December 31, 2022 and 2021. Management is currently unaware of any issues under
review that could result in significant payments, accruals or material deviations from its position.

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Recent Accounting Pronouncements

See Note 2 to the Financial Statements.

Smaller Reporting Company Status

We are a “smaller reporting company,” meaning that the market value of our shares held by non-affiliates is less than $700 million and our annual revenue was
less than $100 million during the most recently completed fiscal year. We may continue to be a smaller reporting company if either (i) the market value of our
shares held by non-affiliates is less than $250 million or (ii) our annual revenue was less than $100 million during the most recently completed fiscal year and
the market value of our shares held by non-affiliates is less than $700 million. As a smaller reporting company, we may choose to present only the two most
recent fiscal years of audited financial statements in our Annual Report on Form 10-K , have reduced disclosure obligations regarding executive compensation,
and smaller reporting companies are permitted to delay adoption of certain recent accounting pronouncements discussed in Note 2 to our consolidated financial
statements located in “Part IV, Item 15., Exhibits and Financial Statement Schedules” in this Annual Report on Form 10-K.

Results of Operations

Comparison of the Years Ended December 31, 2022 and 2021

($ in thousands)
Operating expenses:

Research and development
Research and development – licenses acquired
General and administrative

Total operating expenses
Loss from operations

Other income (expense)

Grant income
Interest income
Interest expense

Total other income (expense)
Net Loss

Research and Development Expenses

For the year ended December 31, 

2022

2021

Change

$

%

$

$

 62,475
 1,474
 12,210
 76,159
 (76,159)

 1,304
 689
 (3,359)
 (1,366)
 (77,525)

$

$

 49,864
 5,842
 11,017
 66,723
 (66,723)

$

 12,611  
 (4,368) 
 1,193  
 9,436  
 (9,436) 

 25 %
 (75)%
 11 %
 14 %
 14 %

 —
 368
 (15)
 353
 (66,370)

 1,304

 321  
 (3,344) 
 (1,719) 
$  (11,155)  

 100 %
 87 %
 22,293 %
 (487)%
 17 %

Research and development expenses primarily consist of personnel related expenses, including salaries, benefits, travel, and other related expenses, stock-based
compensation, payments made to third parties for license, sponsored research and milestone costs related to in-licensed products and technology, payments made
to  third  party  contract  research  organizations  for  preclinical  and  clinical  studies,  investigative  sites  for  clinical  trials,  consultants,  the  cost  of  acquiring  and
manufacturing clinical trial materials, costs associated with regulatory filings, laboratory costs and other supplies.

Research and development expenses increased by approximately $12.6 million from $49.9 million for the year ended December 31, 2021, to $62.5 million for
the year ended December 31, 2022. The increase in research and development expense for the year ended December 31, 2022 was primarily attributable to the
following:

●

●

●

●

$4.3 million for increased research and development employee compensation costs, including stock compensation, as we continue to increase research
and development headcount to support development of our clinical programs;

$2.7 million for increased laboratory supply costs;

$1.7 million for increased vector manufacturing costs;

$2.6 million for increased clinical trial related costs;

72

 
 
    
       
       
       
  
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
  
 
    
  
 
 
 
 
 
 
 
 
 
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●

●

approximately $1.6 million for increased other costs including depreciation, software licenses, assay development and rent; and

offset by approximately $0.3 million for decreased costs for consulting and sponsored research agreements.

Research and development expenses - licenses acquired decreased by $4.4 million from $5.8 million for the year ended December 31, 2021 to $1.5 million for
the year ended December 31, 2022. The decrease in research and development expenses - licenses acquired for the year ended December 31, 2022 was primarily
attributable to the following:

● Approximately $3.1 million for the annual stock dividend to Fortress;

●

●

●

$0.8 million for increased costs related to our license with Mayo Clinic;

$0.3 million related to our LUMC license; and

$0.2 million related to our licenses with COH.

We expect our research and development activities to increase as we develop our existing product candidates and potentially acquire new product candidates,
reflecting increasing costs associated with the following:

●

●

●

●

●

●

employee-related expenses, which include salaries and benefits;

license fees and milestone payments related to in-licensed products and technology;

expenses incurred under agreements with CROs, investigative sites and consultants that conduct our clinical trials and our preclinical activities;

facility expenses, which include rent, utilities and maintenance costs;

the cost of acquiring and manufacturing clinical trial materials; and

costs associated with non-clinical activities, and regulatory approvals.

General and Administrative Expenses

General  and  administrative  expenses  consist  primarily  of  salaries  and  related  expenses,  including  stock-based  compensation,  for  executives  and  other
administrative personnel, recruitment expenses, professional fees and other corporate expenses, including investor relations, legal activities including patent fees,
and facilities-related expenses.

General and administrative expense increased by approximately $1.2 million from $11.0 million for the year ended December 31, 2021, to $12.2 million for the
year ended December 31, 2022. The increase in general and administrative expense for the year ended December 31, 2022, was primarily attributable to the
following:

●

●

●

●

●

●

$0.4  million  for  increased  general  and  administrative  employee  compensation  costs  due  primarily  to  additional  headcount  to  support  the  Company’s
continued growth;

$1.3 million for increased corporate and patent related legal costs;

$0.4 million for increased third-party consulting;

$0.6 million for increased other costs, including outside services; and

offset by approximately $1.3 million for decreased stock-based costs;

$0.2 million decrease in state taxes.

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Table of Contents

We anticipate general and administrative expenses will increase in future periods, reflecting continued and increasing costs associated with:

●

●

●

●

support of our expanded research and development activities, including additional product candidates entering the clinic;

stock compensation granted to key employees and non-employees;

support of business development activities; and

increased professional fees and other costs associated with the regulatory requirements and increased compliance associated with being a publicly traded
company.

Other Income (Expense)

Other  income  (expense)  consists  primarily  of  funds  received  from  the  NIH  grant,  interest  income  earned  on  cash  balances  and  short-term  investments  and
interest  expense  on  the  Company’s  notes  payable.  For  the  year  ended  December  31,  2022,  and  2021,  total  other  income  (expense)  was  approximately  $1.4
million of expense and $0.4 million of income, respectively. The $1.7 million decrease in other income (expense) for the year ended December 31, 2022 was
primarily attributable to increased interest expense of $3.3 million partially offset by $1.3 million of grant income and increased interest income of $0.3 million.

We expect interest expense to remain higher so long as the Term Loan is outstanding. The amount of our interest expense may increase if interest rates continue
to increase because the Term Loan has a variable rate of interest.

Liquidity and Capital Resources

The Company has incurred substantial operating losses and expects to continue to incur significant operating losses for the foreseeable future and may never
become profitable. As of December 31, 2022, the Company had an accumulated deficit of $329.4 million.

The Company has funded its operations to date primarily through the sale of equity and its Term Loan. The Company expects to continue to use the proceeds
from previous financing transactions primarily for general corporate purposes, including financing the Company’s growth, developing new or existing product
candidates, and funding capital expenditures, acquisitions and investments.

The Company will be required to expend significant funds in order to advance the development of its product candidates. The continuation of our business as a
going concern is dependent upon raising additional capital and eventually attaining and maintaining profitable operations. As of December 31, 2022, there is
substantial doubt about the Company’s ability to continue as a going concern for the next 12 months from the date of issuance of these financial statements. The
financial statements included in this Annual Report on Form 10-K do not include any adjustments that might be necessary should operations discontinue.

As of the date of this Annual Report on Form 10-K, our public float was less than $75 million. As a result, we will be limited by the baby shelf rules until such
time as our public float exceeds $75 million, which means we only have the capacity to sell shares up to one-third of our public float under shelf registration
statements in any twelve-month period. If our public float decreases, the amount of securities we may sell under our Form S-3 shelf registration statements will
also decrease. We will remain constrained by the baby shelf rules under our Form S-3 registration statements until such time as our public float exceeds $75
million, at which time the amount of securities we may sell under a Form S-3 registration statement will no longer be limited by the baby shelf rules.

Contractual Obligations

We  enter  into  contracts  in  the  normal  course  of  business  with  licensors,  CROs,  contract  manufacturing  organizations  (CMOs)  and  other  third  parties  for  the
procurement  of  various  products  and  services,  including  without  limitation  biopharmaceutical  development,  biologic  assay  development,  commercialization,
clinical  and  preclinical  development,  clinical  trials  management,  pharmacovigilance  and  manufacturing  and  supply.  These  contracts  typically  do  not  contain
minimum  purchase  commitments  (although  they  may)  and  are  generally  terminable  by  us  upon  written  notice.  Payments  due  upon  termination  or
cancelation/delay consist of payments for services provided or expenses incurred, including non-cancelable obligations of our service providers, up to the date of
cancellation; in certain cases, our contractual arrangements with CROs and CMOs include cancelation and/or delay fees and penalties.

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Cash Flows for the Years Ended December 31, 2022 and 2021

($ in thousands)
Statement of cash flows data:
Total cash (used in) provided by:

Operating activities
Investing activities
Financing activities

Net change in cash, cash equivalents and restricted cash

Operating Activities

For the year ended December 31, 

2022

2021

$

$

 (65,066)
 (2,952)
 34,056
 (33,962)

$

$

 (53,667)
 (5,366)
 70,847
 11,814

Net  cash  used  in  operating  activities  was  $65.1  million  for  the  year  ended  December  31,  2022,  compared  to  $53.7  million  for  the  year  ended  December  31,
2021. Net cash used in operating activities for the year ended December 31, 2022, was primarily due to approximately $77.5 million in net loss, partially offset
by  $4.0  million  change  in  operating  assets  and  liabilities,  $2.7  million  of  depreciation  expense,  $2.3  million  of  non-cash  stock  compensation  expenses,  $1.1
million of common shares issuable for the Founders Agreement, $0.7 million equity fee to Fortress related to the Term Loan, $0.5 million of amortization of
debt discount, $0.4 million of research and development-licenses acquired, $0.2 million loss on disposal of property and equipment, $0.3 million of amortization
of operating lease right-of-use assets, and $0.2 million of equity fee on issuance of common shares to Fortress.

Net  cash  used  in  operating  activities  was  $53.7  million  for  the  year  ended  December  31,  2021,  compared  to  $37.3  million  for  the  year  ended  December  31,
2020. Net cash used in operating activities for the year ended December 31, 2021, was primarily due to approximately $66.4 million in net loss, partially offset
by $4.2 million of common shares issuable for Founders shares, $3.3 million of non-cash stock compensation expenses, $2.2 million of depreciation expense,
$1.9 million of equity fee on issuance of common shares to Fortress and $1.6 million of research and development-licenses acquired.

Investing Activities

Net cash used in investing activities was $3.0 million for the year ended December 31, 2022, representing $2.7 million in purchases of fixed assets and $0.4
million in purchases of research and development licenses, offset by $0.1 million of proceeds from the sale of fixed assets.

Net cash used in investing activities was $5.4 million for the year ended December 31, 2021, representing $4.0 million in purchases of fixed assets and $1.4
million in purchases of research and development licenses.

Financing Activities

Net cash provided by financing activities was $34.1 million during the year ended December 31,  2022, driven  by  (i)  proceeds  from  the  issuance  of  the  Term
Loan of $30.0 million, net of financing costs of $2.7 million; (ii) gross proceeds of $6.6 million, net of offering costs of $0.1 million, from the Mustang ATM;
and (iii) $0.2 million raised from the issuance of the Company’s common shares in connection with the Employee Stock Purchase Plan (“ESPP”).

Net  cash  provided  by  financing  activities  was  $70.8  million  during  the  year  ended  December  31,  2021,  representing  gross  proceeds  of  $71.9  million,  net  of
offering costs of $1.4 million, from the Mustang ATM and $0.3 million raised from the issuance of the Company’s common shares in connection with the ESPP.

Item 7A.     Quantitative and Qualitative Disclosures About Market Risks

We are exposed to fluctuations in interest rates, subject to a designated floor and cap, on our Term Loan. A change in interest rates could have a material impact
on our cash flow. For example, at December 31, 2022, a 100 basis point change in assumed interest rates for our Term Loan would have an annual impact of
approximately $0.3 million on interest expense.

Item 8.       Financial Statements and Supplementary Data.

The information required by this Item is set forth in the financial statements and notes thereto beginning at page F-1 of this Annual Report on Form 10-K.

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Item 9.      Changes in and Disagreements with Accountants on Accounting and Financial Disclosure.

Not applicable.

Item 9A.      Controls and Procedures.

Disclosure Controls and Procedures

Controls and Procedures

Disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) are designed only to provide reasonable assurance that they will
meet  their  objectives.  Under  the  supervision  and  with  the  participation  of  our  management,  including  our  principal  executive  officer  and  principal  financial
officer, we conducted an evaluation of the effectiveness, as of December 31, 2022, of the design and operation of our disclosure controls and procedures, as such
term is defined in Exchange Act Rules 13a-15(e) and 15d-15(e). Based on this evaluation, our principal executive officer and principal financial officer have
concluded that, as of such date, our disclosure controls and procedures are effective to ensure that information required to be disclosed by us in our Exchange
Act  reports  is  recorded,  processed,  summarized,  and  reported  within  the  time  periods  specified  in  the  SEC’s  rules  and  forms,  and  that  such  information  is
accumulated  and  communicated  to  our  management,  including  our  principal  executive  officer  and  principal  financial  officer,  as  appropriate  to  allow  timely
decisions regarding required disclosure.

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  financial  reporting,  as  such  term  is  defined  in  Exchange Act
Rules 13a-15(f) and 15d-15(f). Internal control over financial reporting refers to the process designed by, or under the supervision of, our principal executive
officer and principal financial officer, 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 generally accepted accounting principles,
and includes those policies and procedures that:

(1) pertain to the maintenance of records that in reasonable detail accurately and fairly reflect the transactions and dispositions of our assets;

(2) provide  reasonable  assurance  that  transactions  are  recorded  as  necessary  to  permit  preparation  of  financial  statements  in  accordance  with  generally
accepted  accounting  principles  (“GAAP”),  and  that  our  receipts  and  expenditures  are  being  made  only  in  accordance  with  authorization  of  our
management and directors; and

(3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisitions, use or disposition of our assets that could have a

material effect on the financial statements.

Internal  control  over  financial  reporting  has  inherent  limitations.  Internal  control  over  financial  reporting  is  a  process  that  involves  human  diligence  and
compliance  and  is  subject  to  lapses  in  judgment  and  breakdowns  resulting  from  human  failures.  Internal  control  over  financial  reporting  also  can  be
circumvented by collusion or improper management override. Because of such limitations, there is a risk that material misstatements may not be prevented or
detected on a timely basis by internal control over financial reporting. However, these inherent limitations are known features of the financial reporting process.
Therefore, it is possible to design into the process safeguards to reduce, though not eliminate, this risk.

Our management assessed the effectiveness of our internal control over financial reporting as of December 31, 2022. In making the assessment, management
used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission (“COSO”) in Internal Control - Integrated Framework
(2013).

Based  on  our  assessment,  our  management  has  concluded  that,  as  of  December  31,  2022,  our  internal  controls  over  financial  reporting  were  effective  based
upon those criteria.

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Changes in Internal Controls over Financial Reporting.

There were no changes in our internal control over financial reporting during our most recent fiscal quarter that have materially affected, or are reasonably likely
to materially affect, our internal control over financial reporting.

Item 9B.     Other Information

None.

Item 9C.     Disclosure Regarding Foreign Jurisdiction that Prevents Inspections.

None.

PART III

Item 10.     Directors, Executive Officers and Corporate Governance

The information required by this Item is incorporated herein by reference from our Proxy Statement for our 2023 Annual Meeting of Stockholders.

Item 11.     Executive Compensation

The information required by this Item is incorporated herein by reference from our Proxy Statement for our 2023 Annual Meeting of Stockholders.

Item 12.     Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

The information required by this Item is incorporated herein by reference from our Proxy Statement for our 2023 Annual Meeting of Stockholders.

Item 13.      Certain Relationships and Related Transactions, and Director Independence.

The information required by this Item is incorporated herein by reference from our Proxy Statement for our 2023 Annual Meeting of Stockholders.

Item 14.     Principal Accounting Fees and Services.

The information required by this Item is incorporated herein by reference from our Proxy Statement for our 2023 Annual Meeting of Stockholders.

Item 15.     Exhibits, Financial Statement Schedules.

(a) Financial Statements.

The following financial statements are filed as part of this Form 10-K:

PART IV

Report of Independent Registered Public Accounting Firm (KPMG LLP, New York, NY; PCAOB ID: 185)

Financial Statements:
Balance Sheets as of December 31, 2022 and 2021
Statements of Operations for the Years Ended December 31, 2022 and 2021
Statements of Changes in Stockholders’ Equity for the Years Ended December 31, 2022 and 2021
Statements of Cash Flows for the Years Ended December 31, 2022 and 2021
Notes to Financial Statements

77

F-2

F-4
F-5
F-6
F-7
F-8 - F-28

 
 
 
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(b) Exhibits.

Exhibit No.
3.1

3.2

3.3

3.4

3.5

3.6

3.7

4.1

4.2

4.3

10.1

10.2

10.3

10.4

Amended and Restated Certificate of Incorporation of Mustang Bio, Inc. (formerly Mustang Therapeutics, Inc.), dated July 26, 2016
(incorporated by reference to the Exhibit 3.1 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Description

Certificate of Amendment of the Amended and Restated Certificate of Incorporation of Mustang Bio, Inc., dated June 14, 2018 (incorporated
by reference to the Exhibit 3.1 of the Registrant’s Quarterly Report on Form 10-Q (file No. 001-38191) filed with the SEC on June 14, 2018).

Certificate of Amendment of the Amended and Restated Certificate of Incorporation of Mustang Bio, Inc., dated September 30, 2019
(incorporated by reference to the Exhibit 3.1 of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on
September 30, 2019).

Certificate of Amendment of the Amended and Restated Certificate of Incorporation of Mustang Bio, Inc., dated December 4, 2020
(incorporated by reference to the Exhibit 3.1 of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on
December 4, 2020).

Certificate of Amendment of the Amended and Restated Certificate of Incorporation of Mustang Bio, Inc., dated June 17,
2021 (incorporated by reference to the Exhibit 3.1 of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on
June 22, 2021).

Certificate of Amendment of the Amended and Restated Certificate of Incorporation of Mustang Bio, Inc., dated July 5, 2022 (incorporated by
reference to the Exhibit 3.1 of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on July 5, 2022).

Bylaws of Mustang Bio, Inc. (incorporated by reference to the Exhibit 3.2 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the
SEC on July 28, 2016).

Specimen certificates evidencing shares of common stock, Class A common stock and Class A preferred stock (incorporated by reference to
the Exhibit 4.1 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Form of warrant agreement (incorporated by reference to the Exhibit 4.2 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the
SEC on July 28, 2016).

  Description of Securities of Mustang Bio, Inc. **

Second Amended and Restated Founders Agreement between Fortress Biotech, Inc. and Mustang Bio, Inc., dated July 26, 2016 (incorporated
by reference to the Exhibit 10.1 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Management Services Agreement between Fortress Biotech, Inc. and Mustang Bio, Inc., dated March 13, 2015 (incorporated by reference to
the Exhibit 10.2 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Future Advance Promissory Note to Fortress Biotech, Inc., dated May 5, 2016 (incorporated by reference to the Exhibit 10.3 of the
Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Promissory Note to NSC Biotech Venture Fund I, LLC, dated July 5, 2016 (incorporated by reference to the Exhibit 10.4 of the Registrant’s
Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

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Exhibit No.
10.5

Description
Common Stock Warrant issued by Mustang Bio, Inc. to NSC Biotech Venture Fund I, LLC, dated July 5, 2016 (incorporated by reference to
the Exhibit 10.5 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

10.6

10.7

10.8

10.9

10.10

10.11

10.12

License Agreement by and between Mustang Bio, Inc. and City of Hope, dated March 17, 2015 (incorporated by reference to the Exhibit 10.6
of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016). #

Sponsored Research Agreement by and between Mustang Bio, Inc. and City of Hope, dated March 17, 2015 (incorporated by reference to the
Exhibit 10.7 of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Mustang Bio, Inc. 2016 Incentive Plan (incorporated by reference to the Exhibit 10.8 of the Registrant’s Form 10-12G (file No. 000-55668)
filed with the SEC on July 28, 2016). †

Mustang Bio, Inc. Non-Employee Directors Compensation Plan (incorporated by reference to the Exhibit 10.9 of the Registrant’s Form 10-
12G (file No. 000-55668) filed with the SEC on July 28, 2016). †

Agreement by and between Mustang Bio, Inc. and Chord Advisors, LLC, dated April 8, 2016 (incorporated by reference to the Exhibit 10.10
of the Registrant’s Form 10-12G (file No. 000-55668) filed with the SEC on July 28, 2016).

Board Advisory Services Agreement by and between Mustang Bio, Inc. and Caribe BioAdvisors, LLC, dated January 1, 2017 (incorporated by
reference to the Exhibit 10.11 of the Registrant’s Annual Report on Form 10-K (file No. 000-55668) filed with the SEC on March 31, 2017).

Exclusive License Agreement by and between Mustang Bio, Inc. and The Regents of the University of California, dated March 17, 2017
(incorporated by reference to the Exhibit 10.4 of the Registrant’s Quarterly Report on Form 10-Q (file No. 000-55668) filed with the SEC on
August 14, 2017). #

10.13

  Exclusive License Agreement (IV/ICV) by and between Mustang Bio, Inc. and City of Hope, dated February 17, 2017.

Filed as Exhibit 10.5 on the Company’s Form 10-Q filed on August 14, 2017 (incorporated by reference to the Exhibit 10.5 of the Registrant’s
Quarterly Report on Form 10-Q (file No. 000-55668) filed with the SEC on August 14, 2017). #

10.14

  Amended and Restated Exclusive License Agreement (CD123) by and between Mustang Bio, Inc. and City of Hope, dated February 17, 2017
(incorporated by reference to the Exhibit 10.14 of the Registrant’s Annual Report on Form 10-K (file No. 000-55668) filed with the SEC on
March 31, 2017). #

10.15

  Amended and Restated Exclusive License Agreement (IL13Ra2) by and between Mustang Bio, Inc. and City of Hope, dated February 17,

2017 (incorporated by reference to the Exhibit 10.15 of the Registrant’s Annual Report on Form 10-K (file No. 000-55668) filed with the SEC
on March 31, 2017). #

10.16

  Amended and Restated Exclusive License Agreement (Spacer) by and between Mustang Bio, Inc. and City of Hope, dated February 17, 2017
(incorporated by reference to the Exhibit 10.16 of the Registrant’s Annual Report on Form 10-K (file No. 000-55668) filed with the SEC on
March 31, 2017). #

10.17

  Employment Agreement between Manuel Litchman and Mustang Bio, Inc., effective as of April 24, 2017 (incorporated by reference to the

Exhibit 10.1 of the Registrant’s Current Report on Form 8-K (file No. 000-55668) filed with the SEC on April 24, 2017). †

10.18

  License Agreement (CSI) by and between Mustang Bio, Inc. and City of Hope, dated May 31, 2017  (incorporated by reference to the Exhibit 

10.1 of the Registrant’s Quarterly Report on Form 10-Q/A (file No. 001-38191) filed with the SEC on November 14, 2017). #

10.19

  License Agreement (PSCA)by and between Mustang Bio, Inc. and City of Hope, dated May 31, 2017 (incorporated by reference to the Exhibit

10.2 of the Registrant’s Quarterly Report on Form 10-Q/A (file No. 001-38191) filed with the SEC on November 14, 2017). #

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Exhibit No.

10.20

  License Agreement (HER2) by and between Mustang Bio, Inc. and City of Hope, dated May 31, 2017  (incorporated by reference to the 
Exhibit 10.3 of the Registrant’s Quarterly Report on Form 10-Q/A (file No. 001-38191) filed with the SEC on November 14, 2017). #

Description

10.21

  Lease Agreement by and between Mustang Bio, Inc.  and WCS - 377 Plantation Street, Inc., dated October 27, 2017 (incorporated by 

reference to the Exhibit 10.1 of the Registrant’s Quarterly Report on Form 10-Q (file No. 001-38191) filed with the SEC on November 14, 
2017).

10.22

10.23

  Sublease Agreement by and between Mustang Bio, Inc., and The Paul Reverse Life Insurance Company, dated June 14, 2022. **

First Amendment to Sublease Agreement by and between Mustang Bio, Inc. and The Paul Revere Life Insurance Company, dated October 25,
2022. **

10.24

  Mustang Bio, Inc. 2019 Employee Stock Purchase Plan (incorporated by reference to the Exhibit 10.1 of the Registrant’s Quarterly Report on

Form 10-Q (file No. 001-38191) filed with the SEC on August 9, 2019).†

10.25

10.26

10.27

10.28

10.29

10.30

16.1

23.1

24.1

31.1

31.2

Second Amendment to the Mustang Bio, Inc. 2016 Equity Incentive Plan, dated June 17, 2021 (incorporated by reference to the Exhibit 10.1
of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on June 22, 2021). †

Third Amendment to Mustang Bio, Inc. 2016 Equity Incentive Plan, dated June 21,2022 (incorporated by reference to the Exhibit 10.1 of the
Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on June 24, 2022). †

Amendment to the Mustang Bio, Inc. 2019 Employee Stock Purchase Plan, dated June 17, 2021 (incorporated by reference to the Exhibit 10.2
of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on June 22, 2021). †

Warrant to Purchase Common Stock issued to Runway Growth Finance Corp., dated March 4, 2022 (incorporated by reference to the Exhibit
4.1 of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed with the SEC on March 8, 2022).

Loan and Security Agreement by and between Mustang Bio, Inc., the Borrower, the Lenders, and Runway Growth Finance Corp. (as agent),
dated March 4, 2022 (incorporated by reference to the Exhibit 99.1 of the Registrant’s Current Report on Form 8-K (file No. 001-38191) filed
with the SEC on March 8, 2022).

First Amendment to Loan and Security Agreement by and between Mustang Bio, Inc., the Borrower, the Lenders and Runway Growth Finance
Corp. (as agent), dated December 7, 2022 (incorporated by reference to the Exhibit 10.1 of the Registrant’s Current Report on Form 8-K (file
No. 001-38191) filed with the SEC on December 13, 2022).

Letter from BDO USA, LLP to the Securities and Exchange Commission dated September 22, 2021, incorporated by
reference to the Form 8-K filed on September 24, 2021. *

Consent of Independent Registered Public Accounting Firm, KPMG, LLP, Hartford, Connecticut.

  Power of Attorney (included on signature page).

Certification of President and Chief Executive Officer, pursuant to Rule 13a-14(a) of the Exchange Act, as adopted pursuant to Section 302 of
the Sarbanes-Oxley Act of 2002.

Certification of Principal Financial Officer, pursuant to Rule 13a-14(a) of the Exchange Act, as adopted pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002.

80

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Exhibit No.
32.1

32.2

101

Certification of President and Chief Executive Officer, pursuant to Rule 13a-14(b) of the Exchange Act and 18 U.S.C. Section 1350, as
adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Description

Certification of Principal Financial Officer, pursuant to Rule 13a-14(b) of the Exchange Act and 18 U.S.C. Section 1350, as adopted pursuant
to Section 906 of the Sarbanes-Oxley Act of 2002.

The following financial information from Mustang Bio, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2022, formatted
in Inline Extensible Business Reporting Language (iXBRL): (i) the Balance Sheets, (ii) the Statements of Operations, (iii) the Statement of
Stockholders’ Equity, (iv) the Statements of Cash Flows, and (v) Notes to the Financial Statements (filed herewith).

104

Cover Page Interactive Data File (formatted as Inline XBRL and contained in exhibit 101)

#     Confidential treatment has been granted with respect to omitted portions of this exhibit.

†     Indicates management contract or compensatory plan or arrangement.

**   Filed herewith.

Item 16.      Form 10-K Summary.

None.

81

 
 
 
 
 
 
 
 
 
 
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INDEX TO FINANCIAL STATEMENTS

Report of Independent Registered Public Accounting Firm (KPMG LLP, New York, NY; PCAOB ID: 185)
Balance Sheets as of December 31, 2022 and 2021
Statements of Operations for the Years Ended December 31, 2022 and 2021
Statements of Changes in Stockholders’ Equity for the Years Ended December 31, 2022 and 2021
Statements of Cash Flows for the Years Ended December 31, 2022 and 2021
Notes to Financial Statements

F-2
F-4
F-5
F-6
F-7
F-8 – F-28

F-1

Table of Contents

Report of Independent Registered Public Accounting Firm

To the Stockholders and Board of Directors
Mustang Bio, Inc.:

Opinion on the Financial Statements

We have audited the accompanying balance sheets of Mustang Bio, Inc. (the Company) as of December 31, 2022 and 2021, the related statements of operations,
stockholders’  equity,  and  cash  flows  for  the  years  then  ended,  and  the  related  notes  (collectively,  the  financial  statements).  In  our  opinion,  the  financial
statements present fairly, in all material respects, the financial position of the Company as of December 31, 2022 and 2021, and the results of its operations and
its cash flows for each of the years then ended, in conformity with U.S. generally accepted accounting principles.

Going Concern

The accompanying financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the financial
statements, the Company’s expectation to generate operating losses and negative operating cash flows in the future, projections of future inability to meet certain
financial debt covenants, and the need for additional funding to support its planned operations raises substantial doubt about its ability to continue as a going
concern. Management’s plans in regard to these matters are also described in Note 1. The financial statements and supplemental information do not include any
adjustments that might result from the outcome of this uncertainty.

Basis for Opinion

These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these 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.

/s/ KPMG LLP

We have served as the Company’s auditor since 2021.

Hartford, Connecticut
March 29, 2023

F-2

 
 
Table of Contents

MUSTANG BIO, INC.
BALANCE SHEETS
(in thousands, except for share and per share amounts)

December 31, 
2022

December 31, 
2021

ASSETS
Current Assets:

Cash and cash equivalents
Other receivables - related party
Prepaid expenses and other current assets

Total current assets

Property, plant and equipment, net
Fixed assets - construction in process
Restricted cash
Other assets
Operating lease right-of-use asset, net
Total Assets

LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Liabilities:

Accounts payable and accrued expenses
Payables and accrued expenses - related party
Operating lease liabilities - short-term

Total current liabilities

Deferred income
Note payable, long-term, net
Operating lease liabilities - long-term
Total Liabilities

Commitments and Contingencies (Note 7)

Stockholders’ Equity
Preferred stock ($0.0001 par value), 2,000,000 shares authorized, 250,000 shares of Class A preferred
stock issued and outstanding as of December 31, 2022 and 2021, respectively
Common stock ($0.0001 par value), 200,000,000 and 150,000,000 shares authorized as of
December 31, 2022 and 2021, respectively

Class A common shares, 845,385 shares issued and outstanding as of December 31, 2022 and 2021,
respectively
Common shares, 106,501,663 and 93,582,991 shares issued and outstanding as of December 31, 2022
and 2021, respectively

Common stock issuable, 2,807,008 and 2,536,607 shares as of December 31, 2022 and 2021,
respectively
Additional paid-in capital
Accumulated deficit
Total Stockholders’ Equity
Total Liabilities and Stockholders’ Equity

See accompanying notes to financial statements.

F-4

$

$

$

$

$

$

$

75,656
36
3,160
78,852

8,440
951
1,000
261
2,918
92,422

13,731
766
612
15,109

270
27,436
3,334
46,149

—

—

11

109,618
50
2,038
111,706

9,025
2,027
1,000
362
1,050
125,170

9,744
723
348
10,815

270
—
1,685
12,770

—

—

9

1,109
374,522
(329,369)
46,273
92,422

$

4,329
359,906
(251,844)
112,400
125,170

    
    
 
   
  
 
   
  
 
 
 
 
 
 
 
  
 
  
 
 
 
 
 
 
 
 
 
  
 
  
 
  
 
  
 
  
 
  
 
 
 
  
 
  
 
 
 
 
 
 
 
 
  
 
  
 
  
 
  
 
  
 
  
 
  
 
 
 
  
 
  
 
 
 
 
 
 
 
 
 
 
 
 
Table of Contents

MUSTANG BIO, INC.
STATEMENTS OF OPERATIONS
(in thousands, except for share and per share amounts)

Operating expenses:

Research and development
Research and development – licenses acquired
General and administrative

Total operating expenses
Loss from operations

Other income (expense)

Grant income
Interest income
Interest expense

Total other income (expense)
Net Loss

Net loss per common share outstanding, basic and diluted

For the year ended December 31, 

2022

2021

$

$

$

$

62,475
1,474
12,210
76,159
(76,159)

1,304
689
(3,359)
(1,366)
(77,525) $

49,864
5,842
11,017
66,723
(66,723)

—
368
(15)
353
(66,370)

(0.75) $

(0.76)

Weighted average number of common shares outstanding, basic and diluted

103,432,603

87,885,235

See accompanying notes to financial statements.

F-5

    
    
 
    
  
 
 
 
 
 
 
 
 
 
  
 
  
 
  
 
  
 
 
 
 
 
 
 
 
  
 
  
 
  
 
 
Table of Contents

MUSTANG BIO, INC.
STATEMENTS OF STOCKHOLDERS’ EQUITY
(in thousands, except share amounts)

Class A Preferred Stock
     Amount

     Shares

     Shares

     Amount

Class A Common Shares

Common Shares

Shares
70,920,693

$
—  

     Amount
$
7
—  
—  

2,001,490

Common
Stock
Issuable
7,939
4,212
(7,577)

Additional
Paid-in
     Capital

$ 275,963

Accumulated
Deficit
(185,474)

$
—  

7,577

$
—  
—  

Total
Stockholders’
Equity 

Balances at December 31, 2020
Common stock issuable - Founders Agreement
Issuance of common shares - Founders Agreement  
Issuance of common shares, net of offering costs -
At-the-Market Offering
Issuance of common shares - Equity fee on At-the-
Market Offering
Issuance of common shares under ESPP
Correction to previously issued shares
Stock-based compensation expenses
Exercise of warrants
Net loss
Balances at December 31, 2021
Common stock issuable - Founders Agreement
Issuance of common shares - Founders Agreement  
Issuance of common shares, net of offering costs -
At-the-Market Offering
Issuance of common shares - Equity fee on At-the-
Market Offering
Issuance of common shares under ESPP
Issuance of common shares - Equity fee on RWG
Debt
Issuance of warrants for RWG Debt
Stock-based compensation expenses
Net loss
Balances at December 31, 2022

250,000

$
—  
—  

—

—
—
—
—  
—  
—  
$
—  
—  

250,000

—

—
—

—
—
—  
—  
$

250,000

—  
—  
—  

—

—
—
—
—  
—  
—  
—  
—  
—  

—

—
—

—
—
—  
—  
—  

845,385

$
—  
—  

—

—
—
—
—  
—  
—  
$
—  
—  

845,385

—

—
—

—
—
—  
—  
$

845,385

—  
—  
—  

—

—
—
—
—  
—  
—  
—  
—  
—  

—

—
—

—
—
—  
—  
—  

19,419,944

2

—

70,620

—  
—  
$
—  

$ 359,906

576,157
114,321
60,999
489,249
138

93,582,991

—  
$
—  

2,536,607

7,878,095

248,247
330,833

954,927
—
969,963

106,501,663

—  
$

—
—
—
—  
—  
—  
9
$
—  
—  

2

—
—

—
—
—  
—  
$
11

(245)
—
—
—  
—  
—  

4,329
1,109
(4,212)

—

(117)
—

—
—
—  
—  

2,129
309
—
3,308

4,212

6,498

283
206

750
384
2,283

1,109

$ 374,522

—  
$

—

—
—
—
—  
—  

(66,370)
(251,844)

$
—  
—  

—

—
—

—
—
—  

(77,525)
(329,369)

$

98,435
4,212
—

70,622

1,884
309
—
3,308
—
(66,370)
112,400
1,109
—

6,500

166
206

750
384
2,283
(77,525)
46,273

See accompanying notes to financial statements.

F-6

    
    
    
    
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table of Contents

MUSTANG BIO, INC.
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:
Issuance of common shares - Equity fee on At-the-Market Offering to Fortress
Common shares issuable for Founders Agreement
Research and development - licenses acquired
Issuance of common shares - Equity fee to Fortress on note payable
Stock-based compensation expenses
Depreciation expense
Amortization of debt discount
Amortization of operating lease right-of-use assets
Loss on disposal of property and equipment
Changes in operating assets and liabilities:

Prepaid expenses and other assets
Other receivables - related party
Accounts payable and accrued expenses
Payable and accrued expenses - related party
Deferred income
Lease liabilities

Net cash used in operating activities

Cash Flows from Investing Activities:

Purchase of research and development licenses

Proceeds from the sale of fixed assets
Purchase of fixed assets

Net cash used in investing activities

Cash Flows from Financing Activities:

Proceeds from issuance of common shares - At-the-Market Offering
Offering costs for the issuance of common shares - At-the-Market Offering
Proceeds from debt issuance
Fees paid on the issuance of debt
Proceeds from issuance of common shares under ESPP

Net cash provided by financing activities

Net change in cash, cash equivalents and restricted cash
Cash, cash equivalents and restricted cash, beginning of the period
Cash, cash equivalents and restricted cash, end of the period

Supplemental disclosure of cash flow information:
Cash paid for interest

Supplemental disclosure of noncash activities:
Fixed assets (acquired but not paid)
Issuance of common shares - Founders Agreement
Research and development licenses included in accounts payable and accrued expenses
Note payable final payment fee (incurred but not paid)
Issuance of warrants - note payable

Lease liabilities arising from obtaining right-of-use assets

For the year ended December 31, 

2022

2021

$

(77,525)

$

(66,370)

166
1,109
365
750
2,283
2,723
470
308
255

(1,021)
14
5,257
43
—
(263)
(65,066)

(365)
127
(2,714)
(2,952)

6,623
(123)
30,000
(2,650)
206
34,056

(33,962)
110,618
76,656

2,710

—
4,212
—
1,050

384
2,176

$

$

$
$
$
$

$
$

1,884
4,212
1,630
—
3,308
2,167
—
139
—

(401)
(35)
(408)
233
270
(296)
(53,667)

(1,380)
—
(3,986)
(5,366)

71,919
(1,381)
—
—
309
70,847

11,814
98,804
110,618

—

1,270
7,577
250
—

—
101

$

$

$
$
$
$

$
$

See accompanying notes to financial statements.

F-7

    
    
 
    
  
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
  
 
  
 
  
 
  
 
 
 
 
 
 
 
  
 
  
 
  
 
  
 
 
 
  
 
  
 
 
 
 
 
  
 
  
 
  
 
  
 
  
 
  
 
  
 
  
Table of Contents

Notes to Financial Statements

Note 1 - Organization and Description of Business

Mustang  Bio,  Inc.  (the  “Company”  or  “Mustang”)  was  incorporated  in  Delaware  on  March  13,  2015.  Mustang  is  as  a  clinical-stage
biopharmaceutical  company  focused  on  translating  today’s  medical  breakthroughs  in  cell  and  gene  therapy  into  potential  cures  for
hematologic cancers, solid tumors and rare genetic diseases. The Company may acquire rights to these technologies by licensing the rights
or otherwise acquiring an ownership interest in the technologies, funding their research and development and eventually either out-licensing
or bringing the technologies to market.

The Company is a majority-controlled subsidiary of Fortress Biotech, Inc. (“Fortress” or “Parent”).

Liquidity and Capital Resources

The  Company  has  incurred  substantial  operating  losses  and  expects  to  continue  to  incur  significant  operating  losses  for  the  foreseeable
future and may never become profitable. As of December 31, 2022, the Company had an accumulated deficit of $329.4 million.

The Company has funded its operations to date primarily through the sale of equity and via debt raises, including its loan and financing
agreement  with  Runaway  Growth  Finance  Corporation  (the  "Lender"),  herein  referred  to  as  the  "Term  Loan."  The  Company  expects  to
continue  to  use  the  proceeds  from  previous  financing  transactions  primarily  for  general  corporate  purposes,  including  financing  the
Company’s growth, developing new or existing product candidates, and funding capital expenditures, acquisitions and investments.

The Company will be required to expend significant funds in order to advance the development of its product candidates. The Company
will  require  additional  financings  through  equity  and  debt  offerings,  collaborations  and  licensing  arrangements  or  other  sources  to  fully
develop,  prepare  regulatory  filings,  obtain  regulatory  approvals  and  commercialize  its  existing  and  any  new  product  candidates.  The
continuation  of  our  business  as  a  going  concern  is  dependent  upon  raising  additional  capital  and  eventually  attaining  and  maintaining
profitable operations.

In  accordance  with  Accounting  Standards  Codification  (“ASC”)  205-40,  Going  Concern,  the  Company  evaluated  whether  there  are
conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one
year  after  the  date  that  these  consolidated  financial  statements  are  issued.  This  evaluation  initially  does  not  take  into  consideration  the
potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued.
When  substantial  doubt  exists  under  this  methodology,  management  evaluates  whether  the  mitigating  effect  of  its  plans  sufficiently
alleviates  substantial  doubt  about  the  Company’s  ability  to  continue  as  a  going  concern.  The  mitigating  effect  of  management’s  plans,
however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the
financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that
raise  substantial  doubt  about  the  entity’s  ability  to  continue  as  a  going  concern  within  one  year  after  the  date  that  these  consolidated
financial  statements  are  issued.  In  performing  its  evaluation,  management  excluded  certain  elements  of  its  operating  plan  that  cannot  be
considered probable. Under ASC 205-40, the future receipt of potential funding from future equity or debt issuances, and the potential sale
of priority review vouchers cannot be considered probable at this time because these plans are not entirely within the Company’s control
nor have been approved by the Board of Directors as of the date of these financial statements.

The Company's expectation to generate operating losses and negative operating cash flows in the future, as well as projections of future
inability to meet certain financial debt covenants, and the need for additional funding to support its planned operations raise substantial
doubt regarding the Company’s ability to continue as a going concern for a period of one year after the date that these consolidated financial
statements are issued. The Company continues to monitor its spending by reducing 2023 expenses, which may include projected savings
through delaying the development timelines of certain programs, or termination of such programs and the pursuit of additional cash
resources through public or private equity or debt financings. The Company has concluded that substantial doubt exists about the
Company’s ability to continue as a going concern for a period of at least 12 months from the date of issuance of these consolidated financial
statements.

F-8

Table of Contents

The  accompanying  financial  statements  have  been  prepared  on  a  going  concern  basis,  which  contemplates  the  realization  of  assets  and
satisfaction  of  liabilities  in  the  ordinary  course  of  business.  The  financial  statements  do  not  include  any  adjustments  relating  to  the
recoverability  and  classification  of  recorded  asset  amounts  or  the  amounts  and  classification  of  liabilities  that  may  be  necessary  if  the
Company is unable to continue as a going concern.

Note 2 - Significant Accounting Policies

Basis of Presentation

The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of
America (“GAAP”). The Company has no subsidiaries.

All inter-company transactions between Fortress and Mustang are classified as due from or due to related party in the financial statements.
The Company believes that the assumptions underlying the financial statements are reasonable.

Segments

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  in  assessing  performance.  The
Company views its operations and manages its business in one operating and reporting segment.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the
reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the
reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and
cash  equivalents  at  December  31,  2022  and  2021,  consisted  of  cash  and  certificates  of  deposit  in  institutions  in  the  United  States.  The
Company maintains its cash and cash equivalent balances with high-quality financial institutions and, consequently, the Company believes
that such funds are currently adequately protected against credit risk. At times, portions of the Company’s cash and cash equivalents may be
uninsured or in deposit accounts that exceed Federal Deposit Insurance Corporation (FDIC) limits, though the Company customarily invests
a significant portion of its cash in CDARS accounts to maximize FDIC insurance coverage across its holdings. As of December 31, 2022,
the Company had not experienced losses on these accounts, and management believes the Company is not exposed to significant risk on
such accounts. 

Other Receivables – Related Party

Other  receivables  include  amounts  due  to  the  Company  from  Fortress  and  Journey  Medical  Corporation,  both  related  parties,  and  is
recorded at the invoiced amount.

Restricted Cash

The Company records cash held in an escrow account as a security deposit for the manufacturing facility in Worcester, Massachusetts, as
restricted cash. The Company had $1.0 million in restricted cash as of December 31, 2022 and 2021, respectively. The Facility initiated cell
processing operations for personalized CAR T and gene therapies in 2018.

F-9

Table of Contents

Property, plant and equipment, net

Property and equipment, net, which consists mainly of laboratory equipment, are carried at cost less accumulated depreciation. Depreciation
is computed over the estimated useful lives of the respective assets, generally five years, using the straight-line method.

Property and equipment - Construction in Process

In connection with the Company’s cell processing facility, the Company incurred costs for the design and construction of the facility and the
purchase  of  equipment;  $1.0  million  and  $2.0  million  are  recorded  in  fixed  assets  -  construction  in  process  on  the  balance  sheet  at
December 31, 2022 and 2021, respectively. Upon completion of the facility’s construction, all costs associated with the buildout will be
recorded as leasehold improvements and amortized over the shorter of the estimated useful lives or the term of the respective leases, upon
the improvement being placed in service.

Research and Development Costs

Research and development costs are expensed as incurred. Advance payments for goods and services that will be used in future research
and development activities are expensed when the activity has been performed or when the goods have been received rather than when the
payment is made. Upfront and milestone payments due to third parties that perform research and development services on the Company’s
behalf will be expensed as services are rendered or when the milestone is achieved.

Research  and  development  costs  primarily  consist  of  personnel  related  expenses,  including  salaries,  benefits,  travel,  and  other  related
expenses,  stock-based  compensation,  payments  made  to  third  parties  for  license  and  milestone  costs  related  to  in-licensed  products  and
technology, payments made to third party contract research organizations for preclinical and clinical studies, investigative sites for clinical
trials, consultants, the cost of acquiring and manufacturing clinical trial materials, costs associated with regulatory filings, laboratory costs
and other supplies.

In  accordance  with  Accounting  Standards  Codification  (“ASC”)  730-10-25-1, Research  and  Development, costs  incurred  in  obtaining
technology licenses are charged to research and development expense if the technology licensed has not reached commercial feasibility and
has  no  alternative  future  use.  The  licenses  purchased  by  the  Company  require  substantial  completion  of  research  and  development,
regulatory and marketing approval efforts to reach commercial feasibility and has no alternative future use. Accordingly, the total purchase
price for the licenses acquired is reflected as research and development - licenses acquired in the Company’s Statements of Operations.

Annual Stock Dividend

In  July  2016,  in  connection  with  the Amended  and  Restated Articles  of  Incorporation,  the  Company  issued 250,000  Class A  preferred
shares to Fortress. The Class A preferred shares entitle the holder to a stock dividend equal to 2.5% of the fully diluted outstanding equity of
the  Company  (the  “Annual  Stock  Dividend”).  The Annual  Stock  Dividend  was  part  of  the  consideration  payable  for  formation  of  the
Company and the identification of certain assets, including the license contributed to Mustang by Fortress (see Note 4).

In June 2018, in connection with the Amended and Restated Articles of Incorporation, the Company amended the Annual Stock Dividend
 due date from March 13th to January 1st.

Pursuant to the Amended and Restated Articles of Incorporation, the Company issued 2,807,008 shares of common stock to Fortress for the
Annual Stock Dividend, representing 2.5% of the fully-diluted outstanding equity of Mustang on January 1, 2023. This was shown in the
Statement of Stockholders’ Equity at December 31, 2022, as Common stock issuable – Founders Agreement. The Company recorded an
expense  of  approximately  $1.1  million  in  research  and  development  -  licenses  acquired  related  to  these  issuable  shares  during  the  year
ended December 31, 2022.

Pursuant to the Amended and Restated Articles of Incorporation, the Company issued 2,536,607 shares of common stock to Fortress for the
Annual Stock Dividend, representing 2.5% of the fully-diluted outstanding equity of Mustang on January 1, 2022. This was shown in the
Statement of Stockholders’ Equity at December 31, 2021, as Common stock issuable –

F-10

Table of Contents

Founders Agreement. The Company recorded an expense of approximately $4.2 million in research and development - licenses acquired
related to these issuable shares during the year ended December 31, 2021.

Fair Value Measurement

The  Company  follows  accounting  guidance  on  fair  value  measurements  for  financial  assets  and  liabilities  measured  at  fair  value  on  a
recurring basis. Under the accounting guidance, fair value is defined as an exit price, representing the amount that would be received to sell
an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. As such, fair value is a
market-based  measurement  that  should  be  determined  based  on  assumptions  that  market  participants  would  use  in  pricing  an  asset  or  a
liability.

The accounting guidance requires fair value measurements be classified and disclosed in one of the following three categories:

Level 1:    Quoted prices in active markets for identical assets or liabilities.

Level  2:        Observable  inputs  other  than  Level  1  prices,  for  similar  assets  or  liabilities  that  are  directly  or  indirectly  observable  in  the

marketplace.

Level  3:        Unobservable  inputs  which  are  supported  by  little  or  no  market  activity  and  that  are  financial  instruments  whose  values  are
determined  using  pricing  models,  discounted  cash  flow  methodologies,  or  similar  techniques,  as  well  as  instruments  for  which  the
determination of fair value requires significant judgment or estimation.

The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when
measuring fair value. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is
significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement
in its entirety requires management to make judgments and consider factors specific to the asset or liability.

Leases

Arrangements meeting the definition of a lease are classified as operating or financing leases and are recorded on the balance sheet as both a
right of use asset and lease liability, calculated by discounting fixed lease payments over the lease term at the rate implicit in the lease or the
Company's incremental borrowing rate. Lease liabilities are increased by interest and reduced by payments each period, and the right of use
asset is amortized over the lease term. For operating leases, interest on the lease liability and the amortization of the right of use asset result
in straight-line rent expense over the lease term. Variable lease expenses are recorded when incurred. In calculating the right of use asset
and lease liability, the Company elects to combine lease and non-lease components. The Company excludes short-term leases having initial
terms of 12 months or less from the new guidance as an accounting policy election and recognizes rent expense on a straight-line basis over
the lease term.

Stock-Based Compensation

The  Company  expenses  stock-based  compensation  to  employees  over  the  requisite  service  period  based  on  the  estimated  grant-date  fair
value of the awards and forfeiture rates.

The  Company  estimates  the  fair  value  of  stock  option  grants  using  the  Black-Scholes  option  pricing  model  or  409a  valuations,  as
applicable. The assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve
inherent uncertainties and the application of management’s judgment.

Income Taxes

The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the
future tax effects attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities
and their respective income tax bases, and operating loss and tax credit carryforwards. The Company establishes a valuation allowance if
management believes it is more likely than not that the deferred tax assets

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will  not  be  recovered  based  on  an  evaluation  of  objective  verifiable  evidence.  For  tax  positions  that  are  more  likely  than  not  of  being
sustained upon audit, the Company recognizes the largest amount of the benefit that is greater than 50% likely of being realized. For tax
positions that are not more likely than not of being sustained upon audit, the Company does not recognize any portion of the benefit.

Net Loss per Share

Net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding during the period less
unvested  restricted  stock.  Since  dividends  are  declared,  paid  and  set  aside  among  the  holders  of  shares  of  common  stock  and  Class A
common shares pro-rata on an as-if-converted basis, the two-class method of computing net loss per share is not required. Diluted net loss
per share does not reflect the effect of shares of common stock to be issued upon the exercise of warrants or outstanding Class A preferred
shares, as their inclusion would be anti-dilutive.

The table below summarizes potentially dilutive securities that were not considered in the computation of diluted net loss per share because
they would be anti-dilutive.

Warrants
Options
Class A Preferred Shares
Unvested restricted stock awards
Unvested restricted stock units
Total

Comprehensive Loss

For the year ended December 31, 

2022
1,052,920  
1,141,675  
250,000  
510,245  
2,488,687  
5,443,527  

2021
3,308,654
1,141,675
250,000
280,983
2,335,557
7,316,869

The Company has no components of other comprehensive loss, and therefore, comprehensive loss equals net loss.

Recent Accounting Pronouncements

In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2020-06, “Debt-
Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-
40):  Accounting  for  Convertible  Instruments  and  Contracts  in  an  Entity’s  Own  Equity,”   which  simplifies  accounting  for  convertible
instruments by removing major separation models required under current GAAP. The ASU removes certain settlement conditions that are
required for equity contracts to qualify for the derivative scope exception, and it also simplifies the diluted earnings per share calculation in
certain areas. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2023,
including interim periods within those fiscal years. Early adoption will be permitted. The Company is currently evaluating the impact of this
standard on its financial statements.

In  June  2016,  FASB  issued  ASU  2016-13, “Financial  Instruments  -  Credit  Losses  (Topic  326):  Measurement  of  Credit  Losses  on
Financial Instruments”. ASU 2016-13 requires that expected credit losses relating to financial assets are measured on an amortized cost
basis and available-for-sale debt securities be recorded through an allowance for credit losses. ASU 2016-13 limits the amount of credit
losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and also requires the
reversal of previously recognized credit losses if fair value increases. Recently, the FASB issued the final ASU to delay adoption for smaller
reporting  companies  to  calendar  year  2023.  The  Company  is  currently  assessing  the  impact  of  the  adoption  of  this ASU  on  its  financial
statements.

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Note 3 - License, Clinical Trial and Sponsored Research Agreements

Research and Development Expenses – All Licenses

For the years ended December 31, 2022 and 2021, the Company recorded the following expense in research and development for licenses
acquired:

($ in thousands)
City of Hope National Medical Center

CD123
IV/ICV
PSCA
HER2

CSL Behring (Calimmune)
Leiden University  Medical Centre
Mayo Clinic
Fortress PIK Dividend
Total

License Agreements

City of Hope

CD123 License (MB-102)

For the year ended December 31, 

2022

2021

$

$

— $

125
—
200
40
—
—
1,109
1,474

$

250
—
250
—
30
350
750
4,212
5,842

In  February  2017,  the  Company  entered  into  an Amended  and  Restated  Exclusive  License Agreement  with  the  City  of  Hope  National
Medical  Center  (“COH”)  to  acquire  intellectual  property  rights  pertaining  to  CD123  specific  CAR  T  technology.  Pursuant  to  this
agreement, the Company and COH acknowledged that an upfront fee was previously paid. In addition, COH is eligible to receive an annual
maintenance fee of $25,000 and milestone payments totaling $14.5 million upon the achievement of certain milestones. Royalty payments
in the mid-single digits are due on net sales of licensed products.

For  the  year  ended  December  31,  2021,  the  Company  recorded  a  non-refundable  milestone  payment  of  $0.3  million  for  the  24th  patient
treated in connection with the CD123 study. There were no such expenses for the year ended December 31, 2022.

IV/ICV

In  February  2017,  the  Company  entered  into  an  exclusive  license  agreement  (the  “IV/ICV  License”)  with  COH  to  acquire  intellectual
property rights in patent applications related to the intraventricular and intracerebroventricular methods of delivering T cells that express
CARs. Pursuant to the IV/ICV License, in March 2017, the Company paid COH an upfront fee of $0.1 million. COH is eligible to receive a
milestone payment totaling approximately $0.1 million, upon and subject to the achievement of a milestone, and an annual maintenance fee
of $25,000. Royalty payments in the low single digits are due on net sales of licensed products. The Company is obligated to pay COH
a percentage of certain revenues received in connection with a sublicense in the mid-thirties, but no such payments are due in connection
with sublicenses that are granted in conjunction with the sublicense of other CAR T programs that are licensed from COH to the Company.

For the year ended December 31, 2022, the Company expensed a non-refundable milestone payment of $0.1 million in connection with the
first patent within the Patent Rights issued. There were no such expenses for the year ended December 31, 2021.

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PSCA License (MB-105)

In May 2017, the Company entered into an exclusive license agreement with COH for the use of prostate stem cell antigen (“PSCA”) CAR
T  technology  to  be  used  in  the  treatment  of  prostate  cancer,  pancreatic  cancer  and  other  solid  tumors.  Pursuant  to  this  agreement,  the
Company  paid  an  upfront  fee  of  $0.3  million  and  pays  an  annual  maintenance  fee  of  $50,000.  Additional  payments  are  due  for  the
achievement  of ten development milestones totaling $14.9 million, and royalty payments in the mid-single digits are due on net sales of
licensed products.

For the year ended December 31, 2021, the Company expensed a non-refundable milestone payment of $0.3 million for the twelfth patient
treated in the Phase 1 clinical study of MB-105 at COH. There were no such expenses for the year ended December 31, 2022.

HER2 License (MB-103)

On May 31, 2017, the Company entered into an exclusive license agreement with the COH for the use of human epidermal growth factor
receptor  2  (“HER2”)  CAR  T  technology,  which  will  initially  be  applied  in  the  treatment  of  glioblastoma  multiforme.  Pursuant  to  this
agreement,  the  Company  paid  an  upfront  fee  of  $0.6  million  and  pays  an  annual  maintenance  fee  of  $50,000  (which  began  in  2019).
Additional payments are due for the achievement of ten development milestones totaling $14.9 million, and royalty payments in the mid-
single digits are due on net sales of licensed products.

For the year ended, December 31, 2022, the Company expensed a non-refundable milestone payment of $0.2 million in connection with the
first patent within the Patent Rights issued. There were no such expenses for the year ended December 31, 2021.

CSL Behring (Calimmune) License

On August  23,  2019,  the  Company  entered  into  a  non-exclusive  license  agreement  with  CSL  Behring  (Calimmune,  Inc.)  (“Calimmune
License”) for the rights to the CytegrityTM stable producer cell line for the production of viral vector for our lentiviral gene therapy program
for the treatment of XSCID (MB-107 and MB-207). We previously licensed the XSCID gene therapy program from St. Jude Children’s
Research Hospital, Inc. (“St. Jude”) in August 2018. Pursuant to the terms of the Calimmune License, the Company paid an upfront fee of
$0.2 million. CSL Behring is eligible to receive additional payments totaling $1.2 million upon the achievement of three development and
commercialization milestones. Royalty payments in the low-single digits are due on net sales of licensed products.

For the year ended December 31, 2022 and 2021, the Company expensed a non-refundable milestone payments of $40,000  and  $30,000,
respectively, in connection with the Calimmune license.

LUMC License (MB-110)

On September 8, 2021, the Company entered into an exclusive, worldwide licensing agreement with LUMC for the use of a gene therapy
under  development  for  the  treatment  of  severe  immunodeficiency  caused  by  RAG1  deficiency  (the  “LUMC  License”).  Pursuant  to  the
LUMC  License,  the  Company  expensed  an  upfront  fee  of  $0.4  million.  Additional  payments  are  due  for  the  achievement
of  certain  development  milestones  totaling  up  to  $31  million  and  royalty  payments  in  the  low  to  mid-single  digits  as  a  percentage  of
revenue are due on net sales of licensed products.

For the year ended December 31, 2021, the Company expensed an upfront payment of $0.4 million in connection with the LUMC License.
There were no such expenses for the year ended December 31, 2022.

Mayo Clinic - CAR T Technology License

On April 1, 2021, the Company entered into an exclusive license agreement with Mayo Clinic for a novel technology that may be able to
transform the administration of CAR T therapies and has the potential to be used as an off-the shelf therapy. Pursuant to this agreement, the
Company paid an upfront fee of $0.8 million and will pay an annual maintenance fee of $25,000. Additional payments are due for each of
two licensed products for the achievement of eleven development and

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commercial milestones totaling up to $92.6 million per product, and royalty payments in the mid-single digits as a percentage of revenue
are due on net sales of licensed products.

For  the  year  ended  December  31,  2021,  the  Company  expensed  an  upfront  payment  of  $0.8  million  pursuant  to  the  terms  of  the  license
agreement. There were no such expenses for the year ended December 31, 2022.

Research and Development Expenses - Sponsored Research and Clinical Trial Agreements

For the year ended December 31, 2022 and 2021, the Company recorded the following expense in research and development for sponsored
research and clinical trial agreements:

($ in thousands)
City of Hope National Medical Center

CD123
IL13Rα2
CS1
HER2
PSCA

Fred Hutchinson Cancer Center - CD20
St. Jude Children's Research Hospital - XSCID
LUMC - RAG1 SCID
Mayo Clinic
Total

City of Hope

CD123 (MB-102) Clinical Research Support Agreement

For the year ended December 31, 
2021
2022

— $

166
1,486
482
784
103
1,987
508
505
968
6,989

$

—
301
1,169
608
697
107
1,979
865
170
695
6,591

$

$

In February 2017, the Company entered into a Clinical Research Support Agreement for CD123 (the “CD123 CRA”). Pursuant to the terms
of  the  CD123  CRA  the  Company  made  an  upfront  payment  of  $19,450  and  will  contribute  an  additional  $0.1  million  per  patient  in
connection with the on-going investigator-initiated study. Further, the Company agreed to fund approximately $ 0.2 million over three years
pertaining to the clinical development of CD123. For the years ended December 31, 2022 and 2021, the Company recorded $0.2 million
and  $0.3  million,  respectively,  in  research  and  development  expenses  in  the  Statements  of  Operations  pursuant  to  the  terms  of  this
agreement.

IL13Rα2 (MB-101) Clinical Research Support Agreements

In February 2017, the Company entered into a Clinical Research Support Agreement for IL13Rα2 (the “IL13Rα2 CRA”). Pursuant to the
terms of the IL13Rα2 CRA the Company made an upfront payment of approximately $9,300 and will contribute an additional $0.1 million
related  to  patient  costs  in  connection  with  the  on-going  investigator-initiated  study.  Further,  the  Company  agreed  to  fund  approximately
$0.2  million  over three years  pertaining  to  the  clinical  development  of  IL13Rα2.  For  the  years  ended  December  31,  2022  and  2021,  the
Company  recorded  $1.5  million  and  $1.2  million,  respectively,  in  research  and  development  expenses  under  the  IL13Rα2  CRA  in  the
Statements of Operations pursuant to the terms of this agreement.

In October 2020, the Company entered into a Clinical Research Support Agreement for the IL13Rα2-directed CAR T program for adult
patients with leptomeningeal glioblastoma, ependymoma or medulloblastoma (the “IL13Rα2 Leptomeningeal CRA”). Pursuant to the terms
of the IL13Rα2 Leptomeningeal CRA, the Company made an upfront payment of approximately $29,000 and will contribute an additional
$0.1 million per patient in connection with the on-going investigator-initiated study. Further, the Company agreed to fund approximately
$0.2 million annually pertaining to the clinical development of the IL13Rα2-directed CAR T therapy.

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In  October  2020,  the  Company  entered  into  a  Sponsored  Research Agreement  (“SRA”)  with  COH  to  conduct  combination  studies  of  a
potential  IL13Rα2  CAR  and  C134  oncolytic  virus  therapy.  Pursuant  to  the  SRA,  the  Company  funded  research  in  the  amount  of  $0.3
million for the program. In November 2022, the SRA was amended to include additional funding of $0.6 million.

In March 2021, the Company entered into a clinical research support agreement for an Institutional Review Board-approved, investigator-
initiated protocol entitled: “Single Patient Treatment with Intraventricular Infusions of IL13Rα2-targeting and HER2-targeting CAR T cells
for a Single Patient (UPN 181) with Recurrent Multifocal Malignant Glioma.” Pursuant to the terms of this agreement, the Company will
contribute up to $0.2 million in connection with the ongoing investigator-initiated study.

CS1 (MB-104) Clinical Research Support Agreement

In  June  2020,  the  Company  entered  into  a  clinical  research  support  agreement  with  COH  in  connection  with  an  Investigator-sponsored
study conducted under an Institutional Review Board-approved, investigator-initiated protocol entitled: “Phase I Study to Evaluate Cellular
Immunotherapy  Using  Memory-Enriched  T  Cells  Lentivirally  Transduced  to  Express  a  CS1-Targeting,  Hinge-Optimized,  41BB-
Costimulatory Chimeric Antigen Receptor and a Truncated EGFR Following Lymphodepleting Chemotherapy in Adult Patients with CS1+
Multiple Myeloma.” The CAR T being studied under this protocol has been designated as MB-104. Under the terms of the agreement the
Company will reimburse COH for costs associated with this trial not to exceed $2.4 million. The agreement will expire upon the delivery of
a  final  study  report  or  earlier.  For  the  years  ended  December  31,  2022  and  2021,  the  Company  recorded  $0.5  million  and  $0.6  million,
respectively,  in  research  and  development  expenses  in  the  Statements  of  Operations  pursuant  to  the  terms  of  this  agreement.  Since
inception, the Company has reimbursed COH $1.8 million.

HER2 (MB-103) Clinical Research Support Agreement

In  September  2020,  the  Company  entered  into  a  clinical  research  support  agreement  with  COH  in  connection  with  an  Investigator-
sponsored  study  conducted  under  an  Institutional  Review  Board-approved,  investigator-initiated  protocol  entitled:  “Phase  I  Study  of
Cellular Immunotherapy using Memory-Enriched T Cells Lentivirally Transduced to Express a HER2-Specific, Hinge-Optimized, 41BB-
Costimulatory  Chimeric  Receptor  and  a  Truncated  CD19  for  Patients  with  Recurrent/Refractory  Malignant  Glioma.”  The  CAR  T  being
studied under this protocol has been designated as MB-103. Under the terms of the agreement the Company will pay COH $29,375 upon
execution  and  will  reimburse  COH  for  costs  associated  with  this  trial  not  to  exceed  $3.0  million.  The  agreement  will  expire  upon  the
delivery of a final study report or earlier. For the year ended December 31, 2022 and 2021, the Company recorded $ 0.8 million and $0.7
million, respectively, in research and development expenses in the Statements of Operations pursuant to the terms of this agreement. Since
inception, the Company has reimbursed $3.0 million.

PSCA (MB-105) Clinical Research Support Agreement

In October 2020, the Company entered into a clinical research support agreement with COH in connection with an Investigator-sponsored
study  conducted  under  an  Institutional  Review  Board-approved,  investigator-initiated  protocol  entitled:  “A  Phase  1b  study  to  evaluate
PSCA-specific chimeric antigen receptor (CAR)-T cells for patients with metastatic castration resistant prostate cancer.” The CAR T being
studied under this protocol has been designated as MB-105. Under the terms of the agreement the Company will pay COH $33,000 upon
execution  and  will  reimburse  COH  for  costs  associated  with  this  trial  not  to  exceed  $2.3  million.    The  agreement  will  expire  upon  the
delivery of a final study report or earlier. For the years ended December 31, 2022 and 2021, the Company recorded $0.1 million and $0.1
million, respectively, in research and development expenses in the Statements of Operations pursuant to the terms of this agreement. Since
inception, the Company has reimbursed $0.4 million.

Fred Hutch

CD20 Clinical Trial Agreement

On July 3, 2017, in conjunction with the CD20 Technology License from Fred Hutch, we entered into an investigator-initiated clinical trial
agreement (“CD20 CTA”) to provide partial funding for a Phase 1/2 clinical trial at Fred Hutch

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evaluating  the  safety  and  efficacy  of  the  CD20  Technology  in  patients  with  relapsed  or  refractory  B-cell  non-Hodgkin  lymphomas.  In
connection with the CD20 CTA, the Company agreed to fund up to $5.3 million of costs associated with the clinical trial, which commenced
during the fourth quarter of 2017. In November 2020, the CD20 CTA was amended to include additional funding of approximately $ 1.8
million for the treatment of five patients with chronic lymphocytic leukemia and other research costs. In January 2022, the CD20 CTA was
amended to include additional funding of $2.2 million increasing the total payment obligation of the Company in connection with the CD20
CTA not to exceed $9.3 million.

For  the  years  ended  December  31,  2022  and  2021,  the  Company  recorded  $2.0  million  and  $2.0  million,  respectively,  in  research  and
development  expenses  in  the  Statements  of  Operations  pursuant  to  the  terms  of  this  agreement.  Since  inception,  the  Company  has
reimbursed Fred Hutch $7.2 million.

XSCID (MB-107) Data Transfer Agreement with St. Jude

In  June  2020,  the  Company  entered  into  a  Data  Transfer Agreement  with  St.  Jude  under  which  we  will  reimburse  St.  Jude  for  costs
associated with St. Jude’s clinical trial for the treatment of infants with XSCID.  Pursuant to the terms of this agreement the Company paid
an upfront fee of $1.1 million in July 2020, and will continue to reimburse St. Jude for costs incurred in connection with this clinical trial.
For  the  years  ended  December  31,  2022  and  2021,  the  Company  recorded  $0.5  million  and  $0.9  million,  respectively,  in  research  and
development  expenses  in  the  Statements  of  Operations  pursuant  to  the  terms  of  this  agreement.  Since  inception,  the  Company  has
reimbursed St. Jude $3.0 million.

RAG1-SCID (MB-110) Sponsored Research Support Agreement with LUMC

On September 8, 2021, in connection with the LUMC License, the Company entered into an SRA with LUMC under which the Company
will fund research in the amount of approximately $0.5 million annually over a period of 5 years. The research performed pursuant to this
agreement  will  support  technology  the  Company  has  licensed  from  LUMC  for  the  use  of  a  gene  therapy  under  development  for  the
treatment  of  severe  immunodeficiency  caused  by  RAG1.  For  the  year  ended  December  31,  2022  and  2021,  the  Company  recorded  $0.5
million and $0.2 million, respectively, in research and development expenses in the Statements of Operations pursuant to the terms of this
agreement.

Sponsored Research Support Agreement with Mayo Clinic  

In  June  2021,  the  Company  entered  into  an  SRA  with  Mayo  Clinic  under  which  the  Company  will  fund  research  in  the  amount  of
$2.1  million  over  a  period  of two years.  The  research  performed  pursuant  to  this  agreement  will  support  technology  the  Company  has
licensed  from  Mayo  Clinic  for  a  novel  technology  that  may  be  able  to  transform  the  administration  of  CAR  T  therapies  and  has  the
potential to be used as an off-the-shelf therapy. In October 2022, the SRA was amended to include additional funding of approximately $0.1
million. For the year ended December 31, 2022 and 2021, the Company recorded $1.0 million and $0.7 million, respectively, in research
and development expenses in the Statements of Operations pursuant to the terms of this agreement.

Note 4 - Related Party Agreements

Founders Agreement and Management Services Agreement with Fortress

Effective March 13, 2015, the Company entered a Founders Agreement with Fortress, which was amended and restated on May 17, 2016,
and again on July 26, 2016 (the “Mustang Founders Agreement”). The Mustang Founders Agreement provides that, in exchange for the time
and capital expended in the formation of Mustang and the identification of specific assets the acquisition of which result in the formation of
a  viable  emerging  growth  life  science  company,  Fortress  loaned  $2.0  million,  representing  the  up-front  fee  required  to  acquire  the
Company’s license agreement with COH. The Mustang Founders Agreement has a term of  15 years, which upon expiration automatically
renews for successive one-year periods unless terminated by Fortress and the Company or a Change in Control (as defined in the Mustang
Founders Agreement) occurs. Concurrently with the second amendment on July 26, 2016, to the Mustang Founders Agreement, Fortress
entered into an Exchange Agreement whereby Fortress exchanged its 7.25 million Class B Common shares for 7.0 million common shares
and 250,000 Class A Preferred shares. Class A Preferred Stock is identical to common stock other than as to voting

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rights,  conversion  rights  and  the  PIK  Dividend  right  (as  described  below).  Each  share  of  Class A  Preferred  Stock  is  entitled  to  vote  the
number of votes that is equal to one and one-tenth (1.1) times a fraction, the numerator of which is the sum of (A) the shares of outstanding
Mustang common stock and (B) the whole shares of Mustang common stock into which the shares of outstanding Class A Common Stock
and Class A Preferred Stock are convertible and the denominator of which is the number of shares of outstanding Class A Preferred Stock.
Thus, the Class A Preferred Stock will at all times constitute a voting majority. Each share of Class A Preferred Stock is convertible, at
Fortress’  option,  into  one  fully  paid  and  nonassessable  share  of  Mustang  common  stock,  subject  to  certain  adjustments. As  holders  of
Class A  Preferred  Stock,  Fortress  will  receive  on  each  January  1  (each  a  “PIK  Dividend  Payment  Date”)  until  the  date  all  outstanding
Class A Preferred Stock is converted into common stock, pro rata per share dividends paid in additional fully paid and nonassessable shares
of common stock (“PIK Dividends”) such that the aggregate number of shares of common stock issued pursuant to such PIK Dividend is
equal to two and one-half percent (2.5%) of Mustang’s fully-diluted outstanding capitalization on the date that is one (1) business day prior
to any PIK Dividend Payment Date.

As additional consideration under the Mustang Founders Agreement, Mustang will also: (i) pay an equity fee in shares of common stock,
payable within five (5) business days of the closing of any equity or debt financing for Mustang that occurs after the effective date of the
Mustang Founders Agreement and ending on the date when Fortress no longer has majority voting control in the Company’s voting equity,
equal to two and one-half (2.5%) of the gross amount of any such equity or debt financing; and (ii) pay a cash fee equal to four and one-
half percent (4.5%) of the Company’s annual net sales, payable on an annual basis, within ninety (90) days of the end of each calendar year.
In the event of a Change in Control, the Company will pay a one-time change in control fee equal to five (5x) times the product of (A) net
sales for the twelve (12) months immediately preceding the change in control and (B) four and one-half percent (4.5%) (see Note 9).

Effective  as  of  March  13,  2015,  the  Company  entered  into  a  Management  Services Agreement  (the  “MSA”)  with  Fortress,  pursuant  to
which Fortress renders advisory and consulting services to the Company. The MSA has an initial term of  five years  and  is  automatically
renewed for successive five-year terms unless terminated in accordance with its provisions. Services provided under the MSA may include,
without limitation, (i) advice and assistance concerning any and all aspects of the Company’s operations, clinical trials, financial planning
and  strategic  transactions  and  financings  and  (ii)  conducting  relations  on  behalf  of  the  Company  with  accountants,  attorneys,  financial
advisors  and  other  professionals  (collectively,  the  “Services”).  The  Company  is  obligated  to  utilize  clinical  research  services,  medical
education, communication and marketing services and investor relations/public relation services of companies or individuals designated by
Fortress,  provided  those  services  are  offered  at  market  prices.  However,  the  Company  is  not  obligated  to  take  or  act  upon  any  advice
rendered from Fortress and Fortress shall not be liable for any of its actions or inactions based upon their advice. Pursuant to the MSA and
the Company’s Certificate of Incorporation,  Fortress  and  its  affiliates,  including  all  members  of  the  Company’s  Board  of  Directors,  will
have  no  fiduciary  or  other  duty  to  communicate  or  present  any  corporate  opportunities  to  the  Company  or  to  refrain  from  engaging  in
business that is similar to that of the Company. In consideration for the Services, the Company will pay Fortress an annual consulting fee of
$0.5 million (the “Annual Consulting Fee”), payable in advance in equal quarterly installments on the first business day of each calendar
quarter in each year, provided, however, that such Annual Consulting Fee shall be increased to $ 1.0 million for each calendar year in which
the  Company  has  net  assets  in  excess  of  $100  million  at  the  beginning  of  the  calendar  year.  The  Company  records fifty  percent  of  the
Annual Consulting Fee in research and development expense and fifty percent in general and administrative expense in the Statement of
Operations.  For  the  years  ended  December  31,  2022  and  2021,  the  Company  recorded  expense  of  $1.0  million  and  $0.5  million,
respectively, related to this agreement.

For  the  year  ended  December  31,  2022,  the  Company  issued 196,952  shares  of  common  stock  and  recorded  zero  shares  issuable  to
Fortress,  which  equaled 2.5%  of  the  gross  proceeds  of  $6.6  million  from  the  sale  of  shares  of  common  stock  under  Mustang’s At-the-
Market Offering. The Company recorded an expense of approximately $0.2 million in general and administrative expenses related to these
shares for the year ended December 31, 2022.

For  the  year  ended  December  31,  2021,  the  Company  issued 576,157  shares  of  common  stock  and  recorded 51,295  shares  issuable  to
Fortress,  which  equaled 2.5%  of  the  gross  proceeds  of  $71.9  million  from  the  sale  of  shares  of  common  stock  under  Mustang’s At-the-
Market Offering. The Company recorded an expense of approximately $1.9 million in general and administrative expenses related to these
shares for the year ended December 31, 2021.

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Payables and Accrued Expenses Related Party

In the normal course of business Fortress pays for certain expenses on behalf of the Company. Such expenses are recorded as Payables and
accrued expenses - related party and are reimbursed to Fortress in the normal course of business.

Director Compensation

Dr. Rosenwald

Pursuant to the terms of the Director Compensation Plan, Dr. Rosenwald will receive a cash fee of $50,000 per year paid quarterly and an
annual stock award of the greater of (i) a number of shares of common stock having a fair market value on the grant date of $50,000  or
(ii) 10,000 shares of common stock, which shares shall vest and become non-forfeitable on the third anniversary of the grant date, subject to
continued service on the Board on such date.

For the year ended December 31, 2022, the Company recognized $100,000 in expense in its Statements of Operations related to the director
compensation, including approximately $50,000 in expense related to equity incentive grants. For the year ended December 31, 2021, the
Company recognized $106,000  in  expense  in  its  Statements  of  Operations  related  to  the  director  compensation,  including  approximately
$56,000 in expense related to equity incentive grants. The Company issued Dr. Rosenwald 71,664  and 13,774 restricted stock awards for
the years ended December 31, 2022 and 2021, respectively.

Mr. Weiss - Advisory Agreement with Caribe BioAdvisors, LLC

The Board of the Company by unanimous written consent approved and authorized the execution of an advisory agreement dated January 1,
2017 (the “Advisory Agreement”), with Caribe BioAdvisors, LLC (the “Advisor”), owned by Michael S. Weiss, the Chairman of the Board,
to provide the board advisory services of Mr. Weiss as Chairman of the Board. Pursuant to the Advisory Agreement, the Advisor will be
paid an annual cash fee of $60,000, paid quarterly and an annual stock award of the greater of (i) a number of shares of common stock
having a fair market value on the grant date of $50,000  or  (ii) 10,000 shares of common stock, which shares shall vest and become non-
forfeitable on the third anniversary of the grant date, subject to continued service on the Board on such date.

For  the  year  ended  December  31,  2022,  the  Company  recognized  $110,000  in  expense  in  its  Statements  of  Operations  related  to  the
advisory agreement, including approximately $50,000 in expense related to equity incentive grants. For the year ended December 31, 2021,
the Company recognized $116,000 in expense in its Statements of Operations related to the advisory agreement, including approximately
$56,000  in  expense  related  to  equity  incentive  grants.  The  Company  issued  Mr.  Weiss 71,664  and 13,774  restricted  stock  awards  for
the years ended December 31, 2022 and 2021, respectively.

Note 5 - Property and Equipment

Mustang’s property and equipment consisted of the following:

($ in thousands)
Computer equipment
Furniture and fixtures
Machinery and equipment
Leasehold improvements
Construction in process
Total property, plant and equipment
Less: accumulated depreciation
Property, plant and equipment, net

     Estimated Useful

Life (in years)
3
5
5
9
N/A

December 31, 
2022

December 31, 
2021

145
370
8,632
7,694
951
17,792
(8,401)
9,391

$

$

145
370
6,550
7,694
2,027
16,786
(5,734)
11,052

$

$

Mustang’s  depreciation  expense  for  the  years  ended  December  2022  and  2021  was  approximately  $2.7  million  and  $2.2  million,
respectively, and was recorded in research and development expense in the Statements of Operations.

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Note 6 - Accounts Payable and Accrued Expenses

At December 31, 2022 and 2021, accounts payable and accrued expenses consisted of the following:

($ in thousands)
Accounts payable
Research and development
Accrued compensation
Other
Total accounts payable and accrued expenses

Note 7 - Commitments and Contingencies

Leases

December 31, 
2022

December 31, 
2021

$

$

6,833
2,782
3,468
648
13,731

$

$

3,512
3,083
2,595
554
9,744

On June 14, 2022, the Company entered into a sublease agreement with The Paul Revere Life Insurance Company. Pursuant to the terms of
the  sublease  lease  agreement,  the  Company  agreed  to  lease 26,503  square  feet,  located  at  1  Mercantile  Street,  Worcester,  MA  (the
“Mercantile  Street  Facility”),  through  January  2030.  The  Company  recorded  a  right  of  use asset  and  related  operating  lease  liability  of
$2.2 million on the Balance Sheet at the lease inception.

On  October  27,  2017,  the  Company  entered  into  a  lease  agreement  with  WCS  -  377  Plantation  Street,  Inc.,  a  Massachusetts  nonprofit
corporation. Pursuant to the terms of the lease agreement, the Company agreed to lease 27,043 square feet from the landlord, located at 377
Plantation  Street  in  Worcester,  MA  (the  “Plantation  Street  Facility”),  through  November  2026,  subject  to  additional  extensions  at  the
Company’s option. Base rent, net of abatements of $0.6 million over the lease term, totals approximately $3.6 million, on a triple-net basis.

The terms of the lease also require that the Company post an initial security deposit of $0.8 million, in the form of $0.5  million  letter  of
credit and $0.3 million in cash, which increased to $1.3 million ($1.0 million letter of credit, $0.3 million in cash) on November 1, 2019.
After the fifth lease year, the letter of credit obligation is subject to reduction.

The Plantation Street Facility began operations for the production of personalized CAR T and gene therapies in 2018.

The Company leases office space and copiers under agreements classified as operating leases that expire on various dates through 2030.
The Company’s lease liabilities result from the lease of its facilities in Massachusetts, which expire in 2030 and 2026, for the Mercantile
Street Facility and Plantation Street Facility, respectively, and its copiers, which expire in 2024. Such leases do not require any contingent
rental  payments,  impose  any  financial  restrictions,  or  contain  any  residual  value  guarantees.  Certain  of  the  Company’s  leases  include
renewal options and escalation clauses; renewal options have not been included in the calculation of the lease liabilities and right of use
assets as the Company is not reasonably certain to exercise the options. The Company does not act as a lessor or have any leases classified
as  financing  leases. At  December  31,  2022,  the  Company  had  operating  lease  liabilities  of  $3.9  million  and  right  of  use  assets  of  $2.9
million, which were included in the Balance Sheet. At December 31, 2021, the Company had operating lease liabilities of $2.0 million and
right of use assets of $1.1 million, which were included in the Balance Sheet.

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The following summarizes quantitative information about the Company’s operating leases:

($ in thousands)
Lease cost

Operating lease cost
Variable lease cost

Total

($ in thousands)
Operating cash flows from operating leases
Weighted-average remaining lease term – operating leases
Weighted-average discount rate – operating leases

Maturities of our operating leases, excluding short-term leases, are as follows:

($ in thousands)
Year ended December 31, 2023
Year ended December 31, 2024
Year ended December 31, 2025
Year ended December 31, 2026
Year ended December 31, 2027
Thereafter
Total
Less present value discount
Operating lease liabilities

Note 8 – Notes Payable

For the Year Ended

December 31, 
2022

December 31, 
2021

565   $
488

1,053   $

315
599
914

For the Year Ended

December 31, 
2022

December 31, 
2021

  $

485
5.9
9.1 %

484
4.8
9.0 %

  $

  $

  $

$

$

529
614
1,139
1,076
650
1,381
5,389
(1,443)
3,946

On March 4, 2022 (the “Closing Date”), the Company entered into a $75.0 million long-term debt facility with Runway Growth Finance
Corp.  (the  “Term  Loan”).  Under  the  Term  Loan,  $ 30.0  million  of  the  $75.0  million  loan  was  funded  on  the  Closing  Date,  with  the
remaining $45.0 million fundable if the Company achieves certain predetermined milestones.

The Term Loan matures on April 15, 2027 (the “Maturity Date”).  As of March 15, 2022, the Company began making monthly payments of
interest  only  until April  1,  2024  (the  “Amortization  Date”).  The Amortization  Date  may  be  extended  to April  1,  2025,  if  the  Company
achieves certain predetermined milestones based on equity raises and the initiation of certain clinical trials. After that, the Company will
make  monthly  payments  of  interest  and  principal.  If  the Amortization  Date  is  extended  to April  1,  2025,  the  monthly  payments  will  be
recalculated  in  equal  amounts  according  to  the  remaining  number  of  payment  dates  through  the  Maturity  Date. All  unpaid  outstanding
principal and accrued and unpaid interest will be due and payable in full on the Maturity Date.

The Term Loan accrues interest at a variable annual rate equal to 8.75% plus the greater of (i) 0.50% and (ii) the three month LIBOR Rate
for U.S. dollar deposits or the rate otherwise reasonably determined by the Lender to be the rate at which U.S. dollar deposits with a term of
three  months  would  be  offered  by  banks  in  London,  England  to  major  banks  in  the  London  or  other  offshore  interbank  market    (the
“Applicable Rate”); provided that the Applicable Rate will not be less than  9.25%. The Applicable Rate at December 31, 2022 was 13.40%.
On December 7, 2022, the Company entered into the First Amendment (the “First Amendment”) to the Loan Agreement by and between
the  Company  and  Runway.  The  First Amendment  amended  certain  definitions  and  other  provisions  of  the  Loan Agreement  to  replace
LIBOR-based benchmark rates applicable to loans outstanding under the Loan Agreement with SOFR-based rates, subject to adjustments as
specified in the First Amendment. For the year ended December 31, 2022, the Company made interest payments of

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$2.7 million, recorded in interest expense in the Statements of Operations. The Company had no interest expense related to debt in 2021.

Pursuant  to  the  terms  of  the  Term  Loan  on  the  Closing  Date  the  Company  paid  the  Lender  upfront  fees  out  of  proceeds  of  $0.4  million
consisting  of  a 1%  commitment  fee  and  a  deposit  of  $75,000.    In  addition,  the  Company  paid  other  cash  fees  directly  to  third  parties
comprising of an advisory fee and legal fees totaling $2.3 million.

Also, in connection with the Term Loan, on March 4, 2022, the Company issued a warrant to the Lender to purchase 748,036 shares of the
Company’s  common  stock  with  an  exercise  price  of  $0.8021  (the  “Warrant”)  via  a  warrant  agreement  (the  “Warrant Agreement”).  The
Warrant is exercisable for ten years from the date of issuance. The Lender may exercise the Warrant with cash or through a net issuance
conversion. The shares of the Company’s common stock will be registered at the Company’s first opportunity after the date of the exercise
of the Warrant. In addition, the provisions of the Warrant Agreement provide for additional warrants to be issued upon funding of the term
loan  tranches.  The  fair  value  of  the  warrant  at  the  grant  date  was  determined  utilizing  a  Black  Scholes  Model  with  the  following
assumptions: risk free rate of return 1.74%, volatility of 57.3%, 10-year life yielding a value of approximately $0.4 million as of March 4,
2022.  The fair value of the warrant was also recorded in debt discount and will be amortized over the life of the Term Loan.

($ in thousands)
Note payable
Discount on note payable
Long-term note payable

December 31,       December 31, 

2022

2021

     Applicable Rate      Maturity

  $

  $

31,050   $
(3,614)
27,436   $

—
—
—

13.40 % April - 2027

Amortization of the debt discount associated with the Term Loan was approximately $0.5 million for the year ended December 31, 2022,
respectively, and was recorded in interest expense in the Statements of Operations. The Company had no expense related to debt discount
amortization in 2021.

The  Company  has  the  option  to  prepay  all  of  the  outstanding  Term  Loan  but  not  less.  Prepayment  would  include  outstanding  principal,
accrued  interest,  prepayment  fee  and  final  payment  which  is  equal  to  the  original  principal  amount  of  the  Term  Loan  times 3.5%  or
$1.1 million and is accreted over the life of the Term Loan.

In addition, the Term Loan is secured by a lien on substantially all of our assets other than certain intellectual property assets and certain
other excluded collateral, and it contains a minimum liquidity covenant and other covenants that include among other items: (i) limits on
indebtedness, repurchase of stock from employees, officers and directors. The Company was in compliance with all applicable covenants as
of December 31, 2022.

The Term Loan contains customary events of default, in certain circumstances subject to customary cure periods. Following an event of
default and any cure period, if applicable, Runway will have the right upon notice to accelerate all amounts outstanding under the Term
Loan, in addition to other remedies available to the lenders as secured creditors of the Company.

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Note 9 - Stockholders’ Equity

Common Stock

The Company, in accordance with its certificate of incorporation, as amended in November 2020 and June 2021, which was retroactively
applied, and July 2022, is authorized to issue (i) 200,000,000 common shares with a par value of $0.0001  per  share,  of  which 1,000,000
shares are designated as Class A Common Stock and the remainder are undesignated Common Stock, and (ii)  2,000,000 shares of Preferred
Stock, 250,000 of which are designated as Class A Preferred Stock and the remainder are undesignated Preferred Stock (see below Stock
Issuances to Fortress and Note 4).

In connection with the Company’s formation, Fortress subscribed for 7,000,000 shares of the Class B Common Stock and 2,000,000 shares
of the Company’s Common Stock, pursuant to the Founders Agreement. Fortress paid the par value of $ 900 in 2016. The fair value of the
Company’s common shares approximated par value as no licenses had been transferred at that time. Dividends, if and when declared, are to
be distributed pro-rata to the Class A, B and Common Stockholders.

The  holders  of  Common  Stock  are  entitled  to one  vote  per  share  of  Common  Stock  held.  The  holders  of  Class A  Common  Stock  are
entitled to the number of votes equal to the number of whole shares of Common Stock into which the shares of Class A Common Stock
held by such holder are convertible and for a period of ten years from its issuance, the holders of the Class A Common Stock have the right
to appoint one member of the board of directors of Mustang; to date, the holders of Class A Common Stock have not yet appointed such
director.

The Class B Common Stockholders are entitled, for each share of Class B Common Stock held, to a number of votes equal to 1.1 times a
fraction, the numerator of which is the sum of (A) the shares of outstanding Common Stock and (B) the whole shares of Common Stock
into which the shares of outstanding Class A Common Stock and the Class B Common Stock are convertible and the denominator of which
is  the  number  of  shares  of  outstanding  Class  B  common  shares.  There  was  no  Class  B  Common  Stock  outstanding  as  of
December 31, 2022.

On November 11, 2020, the Company’s Board adopted resolutions of the Board to ratify, approve and recommend stockholder approval of
an amendment to the Company’s Amended and Restated Certificate of Incorporation, as amended, to revise Article IV, Section A thereof in
order  to  effect  an  increase  in  the  authorized  number  of  shares  of  the  Company’s  common  stock,  par  value  $0.0001,  from 85,000,000  to
125,000,000 (the “Amendment”). On November 11, 2020, the Company received approval of the Amendment by written consent in lieu of
a meeting from the holders of a majority of issued and outstanding shares of the Company’s common and preferred stock. The increase in
authorized shares to 125,000,000 became effective on December 4, 2020.

On June 17, 2021, the stockholders of the Company voted at the 2021 Annual Meeting to approve an amendment to Mustang’s Amended
and Restated Certificate of Incorporation to increase the number of shares of common stock authorized for issuance by 25,000,000 shares,
bringing the total number of authorized shares of common stock to 150,000,000 shares. The increase in authorized shares to 150,000,000
became effective on June 17, 2021.

On June 21, 2022, the stockholders of the Company voted at the 2022 Annual Meeting to approve an amendment to Mustang’s Amended
and Restated Certificate of Incorporation to increase the number of shares of common stock authorized for issuance by 50,000,000 shares,
bringing the total number of authorized shares of common stock to 200,000,000 shares.

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At-the-Market Offering of Common Stock

In July 2018, the Company entered into an At-the-Market Issuance Sales Agreement (the “Mustang ATM”) with B. Riley Securities, Inc.
(formerly B. Riley FBR, Inc.), Cantor Fitzgerald & Co., National Securities Corporation, (now B. Riley FBR, Inc.),  and  Oppenheimer  &
Co. Inc. (each an “Agent” and collectively, the “Agents”), relating to the sale of shares of common stock pursuant to the 2020 S-3. Under
the Mustang ATM, the Company pays the Agents a commission rate of up to  3.0% of the gross proceeds from the sale of any shares of
common stock. On December 31, 2020, the Mustang ATM was amended to add H.C. Wainwright & Co., LLC as an Agent.

During the year ended December 31, 2022, the Company issued approximately 7.9 million shares of common stock at an average price of
$0.84 per share for gross proceeds of $6.6 million under the ATM Agreement. In connection with these sales, the Company paid aggregate
fees of approximately $0.1 million for net proceeds of approximately $6.5 million.

During the year ended December 31, 2021, the Company issued approximately 19.4 million shares of common stock at an average price of
$3.70  per  share  for  gross  proceeds  of  $71.9  million  under  the  ATM  Agreement.  In  connection  with  these  sales,  the  Company  paid
aggregate fees of approximately $1.3 million for net proceeds of approximately $70.6 million.

Pursuant to the Founders Agreement, the Company issued 196,952 shares of common stock to Fortress at a weighted average price of $0.84
per share for the year ended December 31, 2022, and recorded zero shares issuable to Fortress in connection with the shares issued under
the  Mustang  ATM.  Pursuant  to  the  Founders  Agreement,  Mustang  issued  576,157  shares  of  common  stock  to  Fortress  at  a  weighted
average price of $3.70 per share for the year ended December 31, 2021, in connection with the shares issued under the Mustang ATM.

Registration Statements

On October 23, 2020, the Company filed a shelf registration statement No. 333-249657 on Form S-3 (the “2020 S-3”), which was declared
effective on December 4, 2020. Under the 2020 S-3, the Company may sell up to a total of $100.0 million of its securities. As of December
31, 2022, approximately $8.0 million of the 2020 S-3 remains available for sales of securities.

On April 23, 2021, the Company filed a shelf registration statement No. 333-255476 on Form S-3 (the “2021 S-3”), which was declared
effective on May 24, 2021. Under the 2021 S-3, the Company may sell up to a total of $200.0 million of its securities. As of December 31,
2022, there have been no sales of securities under the 2021 S-3.

Stock Issuances to Fortress

Under the terms of the Second Amended and Restated Founders Agreement, which became effective July 22, 2016, Fortress will receive a
grant of shares of our common stock equal to two and one-half percent (2.5%) of the gross amount of any equity or debt financing.

For the year ended December 31, 2022, the Company issued 196,952 shares of common stock, which equaled 2.5% of the gross proceeds
of $6.6 million from the sale of shares of common stock under Mustang’s At-the-Market Offering.

For  the  year  ended  December  31,  2021,  the  Company  issued 576,157  shares  of  common  stock  and  recorded 51,295  shares  issuable  to
Fortress,  which  equaled 2.5%  of  the  gross  proceeds  of  $71.9  million  from  the  sale  of  shares  of  common  stock  under  Mustang’s At-the-
Market Offering.

Equity Incentive Plan

The Company has in effect the 2016 Incentive Plan (the “Incentive Plan”). The Incentive Plan was adopted in 2016 by our stockholders and
the  compensation  committee  of  the  Company’s  board  of  directors  and  is  authorized  to  grant  stock-based  awards  to  directors,  officers,
employees and consultants. The plan initially authorized grants to issue up to 2,000,000 shares of authorized but unissued common stock
and expires 10 years from adoption and limits the term of each option to no more than 10 years from the date of grant.

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In  June  2018,  the  Company’s  stockholders  approved  an  amendment  to  the  Incentive  Plan  to  increase  the  number  of  authorized  shares
issuable  by 3,000,000  shares,  for  a  total  of 5,000,000  shares.  In  June  2021,  the  Company’s  stockholders  approved  an  amendment  to  the
Incentive Plan to increase the number of authorized shares issuable by 3,000,000 shares, for a total of 8,000,000 shares. In June 2022, the
Company’s stockholders approved an amendment to the Incentive Plan to increase the number of authorized shares issuable by 3,000,000
shares, for a total of 11,000,000 shares As of December 31, 2022, 4,462,870 shares are available for issuance of stock-based awards under
the Incentive Plan.

Stock Options

The following table summarizes stock option activities for the year ended December 31, 2022 and 2021:

Outstanding at December 31, 2020
Outstanding at December 31, 2021
Outstanding at December 31, 2022
Options vested and exercisable at December 31, 2022

Weighted Average
Exercise Price

     Weighted Average

Remaining
Contractual Life (in
years)

$
$

$

5.73  
5.73  
5.73  
5.73  

6.31
5.31
4.31
4.31

Stock Options
1,141,675
1,141,675
1,141,675
713,547

As  of  December  31,  2022,  the  Company  had no  unrecognized  stock-based  compensation  expense  related  to  options.  The  Company
accounts for forfeited awards as they occur as permitted.

Restricted Stock Awards

Certain  employees  and  directors  have  been  awarded  restricted  stock.  The  restricted  stock  vesting  consists  of  milestone  and  time-based
vesting. The following table summarizes restricted stock award activities for the year ended December 31, 2022 and 2021:

Nonvested at December 31, 2020
Granted
Vested
Nonvested at December 31, 2021
Granted
Vested
Nonvested at December 31, 2022

Number of Shares
302,114
68,870
(90,001)
280,983
358,320
(129,058)
510,245

     Weighted Average
Grant Date Fair
Value

$

$

$

4.93
3.63
6.69
4.05
0.70
4.89
1.48

As  of  December  31,  2022,  the  Company  had  unrecognized  stock-based  compensation  expense  related  to  restricted  stock  of  $0.4  million,
which is expected to be recognized over a weighted average period of approximately 2.3 years.

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Restricted Stock Units

The following table summarizes restricted stock units’ activities for the year ended December 31, 2022 and 2020:

Nonvested at December 31, 2020
Granted
Forfeited
Vested
Nonvested at December 31, 2021
Granted
Forfeited
Vested
Nonvested at December 31, 2022

Number of Units
1,468,559
1,660,250
(372,873)
(420,379)
2,335,557
1,484,647
(514,999)
(816,518)
2,488,687

     Weighted Average
Grant Date Fair
Value

$

$

$

3.87
3.07
3.60
4.27
3.27
0.76
2.53
2.98
1.84

As  of  December  31,  2022,  the  Company  had  unrecognized  stock-based  compensation  expense  related  to  restricted  stock  units  of
approximately $2.0 million, which is expected to be recognized over a weighted average period of approximately 2.7 years.

The following table summarizes stock-based compensation expense for the years ended December 31, 2022 and 2021 (in thousands).

General and administrative
Research and development
Total stock-based compensation expense

Stock Warrants

For the year ended December 31, 

2022

2021

$

$

700
1,583
2,283

$

$

1,030
2,278
3,308

In connection with the Company’s offering of shares of common stock in a private placement, each investor received a warrant equal to
25% of the common shares purchased in connection with the offering. Further, National Securities Corporation received Placement Agent
Warrants. In connection with the Term Loan on March 4, 2022, the Company issued a warrant to the Lender to purchase  748,036 shares of
the Company's common stock with an exercise price of $0.8021, see Note 8.

A summary of warrant activities for years ended December 31, 2022 and 2021, is presented below:

Outstanding as of December 31, 2020
Expired
Cashless exercised
Outstanding as of December 31, 2021
Expired
Granted
Outstanding as of December 31, 2022

Weighted Average
Exercise Price

     Weighted Average

Remaining
Contractual Life (in
years)

8.21  
8.50

—  
8.02  
8.50  
0.80  
1.52  

1.39
—
—
0.73
—
9.18
8.29

Warrants

5,402,670
(2,093,878)
(138)
3,308,654
(3,003,770)
748,036
1,052,920

$

$

$

Upon the exercise of warrants, the Company will issue new shares of Common Stock.

F-26

    
 
 
 
 
 
 
 
 
 
    
    
    
 
 
    
    
 
 
 
 
 
 
 
 
 
Table of Contents

Employee Stock Purchase Plan

In connection with our Employee Stock Purchase Plan (“ESPP”), eligible employees of Mustang and Fortress can purchase the Company’s
Common Stock at the end of a predetermined offering period at 85% of the lower of the fair market value at the beginning or end of the
offering period.

As of December 31, 2022, 586,010 shares have been purchased and 413,990 shares are available for future sale under the Company’s ESPP.

Note 10 - Income Taxes

The Company has accumulated net losses since inception and has not recorded an income tax provision or benefit during the years ended
December 31, 2022 and 2021.

A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows:

Statutory federal income tax rate
State taxes, net of federal tax benefit
Non-deductible items
Credits
Federal tax rate change
State tax rate change
Other
Change in valuation allowance
Income taxes provision (benefit)

For the year ended December 31,

2022

2021

21 %  
16 %  
(1)%  
5 %  
— %  
— %  
1 %  
(42)%  
—  

21 %
16 %
(1)%
5 %
— %
— %
— %
(41)%
—

The components of the net deferred tax asset as of December 31, 2022 and 2021 are the following ($ in thousands):

Deferred tax assets:

Net operating loss carryovers
Stock compensation and other
Change in fair value of warrant liabilities
Amortization of license
Lease liability
Accruals and reserves
Startup costs
Tax credits
174 Capitalization

Total deferred tax assets

Less: valuation allowance

Net deferred tax assets

Deferred tax liabilities:
Right of use asset

Total deferred tax assets, net

For the year ended December 31, 

2022

2021

$

$

$

75,011
2,399
59
13,375
1,466
1,434
6
15,649
19,787
129,186
(128,101)
1,085

$

$

66,879
2,702
59
13,977
755
1,035
6
9,728
—
95,141
(94,751)
390

(1,085)

— $

(390)
—

The  Company  has  determined,  based  upon  available  evidence,  that  it  is  more  likely  than  not  that  the  net  deferred  tax  asset  will  not  be
realized and, accordingly, has provided a full valuation allowance against its net deferred tax assets as of December 31, 2022 and 2021. A
valuation allowance of approximately $128.1 million and $94.8 million, respectively, was recorded for the years ended December 31, 2022
and 2021.

F-27

 
    
    
 
 
 
 
 
 
 
 
 
 
    
    
 
    
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table of Contents

As of December 31, 2022, the Company had federal and state net operating loss carryforwards of approximately $214.0 million and $463.1
million, respectively. Approximately $190.4 million and $0.2 million of the federal and state net operating loss carryforwards, respectively,
can  be  carried  forward  indefinitely. As  of  December  31,  2022,  the  Company  had  federal  and  state  income  tax  credits  of  approximately
$12.5  million  and  $4.0  million,  respectively,  which  will  begin  to  expire  in 2033.  Under  the  provisions  of  Section  382  of  the  Internal
Revenue Code, a corporation that undergoes an “ownership change”, as defined therein, is subject to limitations on its use of pre-change
NOLs and income tax credits carryforwards to offset future tax liabilities. Certain tax attributes may be subject to an annual limitation as a
result of the Company’s January 2017 capital raise, as it appears to constitute an ownership change under Section 382. Additionally, under
Section 382, annual use of the Company’s net operating loss carryforwards to offset taxable income may be limited based on cumulative
changes in ownership. The Company has not completed an analysis to determine whether any such limitations have been triggered as of
December 31, 2022. The Company has no income tax effect due to the recognition of a full valuation allowance on all of its deferred tax
assets  as  it  believes  that  it  is  more  likely  than  not  that  the  deferred  tax  assets  will  not  be  realized  regardless  of  whether  an  “ownership
change” has occurred.

There are no significant items determined to be unrecognized tax benefits taken or expected to be taken in a tax return, in accordance with
ASC  740  “Income  Taxes”  (“ASC  740”),  which  clarifies  the  accounting  for  uncertainty  in  income  taxes  recognized  in  the  financial
statements,  that  have  been  recorded  on  the  Company’s  financial  statements  for  the  periods  ended  December  31,  2022  and  2021.  The
Company does not anticipate a material change to unrecognized tax benefits in the next twelve months.

Additionally, ASC  740  provides  guidance  on  the  recognition  of  interest  and  penalties  related  to  income  taxes.  There  were no  interest  or
penalties related to income taxes that have been accrued or recognized as of and for the periods ended December 31, 2022 and 2021.

The  Company  is  subject  to  U.S.  federal  and  various  state  taxes. As  of  December  31,  2022,  the  earliest  federal  tax  year  open  for  the
assessment of income taxes under the applicable statutes of limitations is its 2019 tax year.

Beginning with the 2022 tax year, the Company is required to capitalize research and development expenses for tax purposes as defined
under Internal Revenue Code Section 174. For expenses that are incurred for research and development in the U.S., the amounts will be
amortized over 5 years, and for expenses that are incurred for research and development outside the U.S., the amounts will be amortized
over 15 years.  As a result of Section 174 capitalization, the Company recognized a deferred tax asset of $19.8 million.

In response to the COVID-19 pandemic, the Coronavirus Aid, Relief and Economic Security Act ("CARES Act") was signed into law on
March  27,  2020.  The  CARES Act,  among  other  things,  includes  tax  provisions  relating  to  refundable  payroll  tax  credits,  deferment  of
employer's  social  security  payments,  net  operating  loss  utilization  and  carryback  periods  and  modifications  to  the  net  interest  deduction
limitations. The CARES Act did not have a material impact on the Company’s income tax provision for 2022 and 2021. The Company will
continue to evaluate the impact of the CARES Act on its financial position, results of operations and cash flows.

On  December  27,  2020,  the  President  of  the  United  States  signed  the  Consolidated  Appropriations  Act,  2021  (“Consolidated
Appropriations Act”) into law. The Consolidated Appropriations Act is intended to enhance and expand certain provisions of the CARES
Act, allows for the deductions of expenses related to the Payroll Protection Program funds received by companies, and provides an update
to  meals  and  entertainment  expensing  for  2021.  The  Consolidated Appropriations Act  did  not  have  a  material  impact  to  the  Company’s
income tax provision for 2022 and 2021.

Note 11 – Subsequent Events

Our Board of Directors approved, and our stockholders subsequently approved, a reverse stock split of our Common Stock. On March 15,
2023, the Board of Directors set the reverse stock split ratio at 15-for-1. We have filed a Definitive Information Statement on Schedule 14C
in connection with the reverse stock split, and once the applicable waiting periods under SEC and Nasdaq rules have expired we plan to file
a Certificate of Amendment to our Amended and Restated Certificate of Incorporation, as amended, in order to give effect to the reverse
stock split. The ex-dividend date is expected to be determined in April 2023.

F-28

Table of Contents

F-29

Table of Contents

Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrant has duly caused this Form 10-K to be
signed on its behalf by the undersigned, thereunto duly authorized.

SIGNATURES

Mustang Bio, Inc.

By: /s/ Manuel Litchman

Name: Manuel Litchman
Title: President and Chief Executive Officer
(Duly Authorized Signatory and Principal Executive Officer)

  March 29, 2023

Pursuant to the requirements of the Securities Exchange Act of 1934, this Form 10-K has been signed below by the following persons on
behalf of the registrant and in the capacities and on the dates indicated.

Signature

Title

Date

/s/ Michael S. Weiss
Michael S. Weiss

/s/ Manuel Litchman
Manuel Litchman, M.D.

/s/ Lindsay A. Rosenwald
Lindsay A. Rosenwald, M.D.

/s/ Neil Herskowitz
Neil Herskowitz

/s/ Adam Chill
Adam Chill

/s/ Michael Zelefsky
Michael Zelefsky, M.D.

/s/ Eliot Lurier
Eliot Lurier

Executive Chairman of the Board

March 29, 2023

President and Chief Executive Officer

March 29, 2023

Director

Director

Director

Director

Interim Chief Financial Officer
(Principal Financial and Accounting Officer)

82

March 29, 2023

March 29, 2023

March 29, 2023

March 29, 2023

March 29, 2023

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DESCRIPTION OF THE REGISTRANT’S SECURITIES
REGISTERED PURSUANT TO SECTION 12 OF THE 
SECURITIES EXCHANGE ACT OF 1934

DESCRIPTION OF CAPITAL STOCK

EXHIBIT 4.3

When used herein, the terms “Company,” “we,” “our,” and “us” refer to Mustang Bio, Inc.

Capital Stock

The  Company  is  authorized  to  issue  200,000,000  shares  of  common  stock  with  a  par  value  of  $0.0001  per  share,  of  which
1,000,000 shares are designated as Class A common stock and 2,000,000 of preferred stock at $0.0001 par value of which 250,000 are
designated as Class A preferred stock.

The holders of common stock are entitled to one vote per share of common stock held.

The undesignated preferred stock may be issued from time to time in one or more series. The Board of Directors is authorized
to  determine  or  alter  the  dividend  rights,  dividend  rate,  conversion  rights,  voting  rights,  rights  and  terms  of  redemption  (including
sinking fund provisions, if any), the redemption price or prices, the liquidation preferences and other designations, powers, preferences
and  relative,  participating,  optional  or  other  special  rights,  if  any,  and  the  qualifications,  limitations  and  restrictions  granted  to  or
imposed upon any wholly unissued series of preferred stock, and to fix the number of shares of any series of preferred stock (but not
below the number of shares of any such series then outstanding).

Class A Common Stock

The holders of Class A common stock are entitled to the number of votes equal to the number of whole shares of common
stock into which the shares of Class A common shares held by such holder are convertible. For a period of ten years from issuance, the
holders of the Class A common stock have the right to appoint one member of the board of directors of Mustang. To date, the holders
of Class A common stock have not yet appointed such director.

Class A Preferred Stock

The Class A Preferred Stock is identical to undesignated common stock other than as to voting rights, conversion rights, and

the PIK dividend right.

The holders of the outstanding shares of Class A Preferred Stock receive on each January 1 (each a “PIK Dividend Payment
Date”)  after  the  original  issuance  date  of  the  Class  A  Preferred  Stock  until  the  date  all  outstanding  Class  A  Preferred  Stock  is
converted into common stock or redeemed (and the purchase price is paid in full), pro rata per share dividends paid in additional fully
paid and non-assessable shares of common stock such that the aggregate number of shares of common stock issued pursuant to such
PIK dividend is equal to 2.5% of the Corporation’s fully-diluted outstanding capitalization on the date that is one business day prior to
any  PIK  Dividend  Payment  Date  (“PIK  Record  Date”).  In  the  event  the  Class A  Preferred  Stock  converts  into  common  stock,  the
holders shall receive all PIK dividends accrued through the date of such conversion. No dividend or other distribution shall be paid, or
declared and set apart for payment (other than dividends payable solely in capital stock on the capital stock) on the shares of common
stock until all PIK dividends on the Class A Preferred Stock shall have been paid or declared and set apart for payment. All dividends
are non-cumulative.

On  any  matter  presented  to  the  stockholders  for  their  action  or  consideration  at  any  meeting  of  stockholders  (or  by  written
consent of stockholders in lieu of meeting), each holder of outstanding shares of Class A Preferred Stock shall be entitled to cast for
each share of Class A Preferred Stock held by such holder as of the record date for determining stockholders entitled to vote on such
matter,  the  number  of  votes  that  is  equal  to  one  and  one-tenth  (1.1)  times  a  fraction,  the  numerator  of  which  is  the  sum  of  (A)  the
number of shares of outstanding common stock and (B) the whole shares of common stock in to which the shares of outstanding Class
A Common Stock and the Class A Preferred Stock are convertible,

1

and the denominator of which is number of shares of outstanding Class A Preferred Stock. Thus, the Class A Preferred Stock will at all
times constitute a voting majority.

Each share of Class A Preferred Stock is convertible, at the option of the holder, into one fully paid and nonassessable share of
common  stock,  subject  to  certain  adjustments.  If  the  Company,  at  any  time  effects  a  subdivision  or  combination  of  the  outstanding
common stock (by any stock split, stock dividend, recapitalization, reverse stock split or otherwise), the applicable conversion ratio in
effect  immediately  before  that  subdivision  is  proportionately  decreased  or  increased,  as  applicable,  so  that  the  number  of  shares  of
common  stock  issuable  on  conversion  of  each  share  of  Class A  Preferred  Stock  shall  be  increased  or  decreased,  as  applicable,  in
proportion  to  such  increase  or  decrease  in  the  aggregate  number  of  shares  of  common  stock  outstanding.  Additionally,  if  any
reorganization, recapitalization, reclassification, consolidation or merger involving the Company occurs in which the common stock
(but not the Class A Preferred Stock) is converted into or exchanged for securities, cash or other property, then each share of Class A
Preferred Stock becomes convertible into the kind and amount of securities, cash or other property which a holder of the number of
shares of common stock of the Company issuable upon conversion of one share of the Class A Preferred Stock immediately prior to
such  reorganization,  recapitalization,  reclassification,  consolidation  or  merger  would  have  been  entitled  to  receive  pursuant  to  such
transaction.

Additional Features

Other features of our capital stock include:

●

●

●

●

●

Dividend Rights. The holders of outstanding shares of our common stock, including Class A common stock, are entitled
to  receive  dividends  out  of  funds  legally  available  at  the  times  and  in  the  amounts  that  our  board  of  directors  may
determine. All dividends are non-cumulative.

Voting Rights . The holders of our common stock are entitled to one vote for each share of common stock held on all
matters submitted to a vote of the stockholders, including the election of directors. Our certificate of incorporation and
bylaws do not provide for cumulative voting rights.

No  Preemptive  or  Similar  Rights .  The  holders  of  our  common  stock  have  no  preemptive,  conversion,  or  subscription
rights, and there are no redemption or sinking fund provisions applicable to our common stock.

Right to Receive Liquidation Distributions. Upon our liquidation, dissolution, or winding-up, the assets legally available
for distribution to our stockholders would be distributable ratably among the holders of our common stock, including
Class A common stock, outstanding at that time after payment of other claims of creditors, if any.

Fully Paid and Non-Assessable. All of the outstanding shares of our common stock, including Class A common stock,
and the Class A Preferred Stock are duly issued, fully paid and non-assessable.

2

SUBLEASE

Exhibit 10.22

This sublease (this “Sublease”) is made as of June 14, 2022 (the “Effective Date”), by and between THE PAUL

REVERE LIFE INSURANCE COMPANY, a Massachusetts corporation (the “Sublessor”), having a notice address of c/o
Unum Group, 1 Fountain Square, Suite 120, Chattanooga, Tennessee 37402, Attn: Corporate Real Estate Department, and
MUSTANG BIO, INC., a Delaware corporation (the “Sublessee”), having a notice address of 377 Plantation Street,
Worcester, Massachusetts 01605.

RECITALS:

WHEREAS, Sublessor is the Tenant under that certain Lease dated June 17, 2010, by and between CitySquare II
Development Co. LLC (“CitySquare II”) and Sublessor, as affected by that certain Assignment and Assumption of Lease dated
October 4, 2010 by and between CitySquare II and One Mercantile Place LLC (“One Mercantile”), as amended by that certain
Letter Agreement by and between One Mercantile and Sublessor dated November 11, 2011, as further amended by that certain
Second Amendment to Lease dated as of July 5, 2012, by and between One Mercantile and Sublessor, as further amended by
that certain Third Amendment to Lease dated as of December 19, 2012, by and between One Mercantile and Sublessor, as
further affected by that certain Assignment and Assumption of Lease and Guaranty dated December 21, 2012, by and between
One Mercantile and ONEMERC, LLC (the “Master Lessor”), as further amended by that certain Letter Agreement dated May
2, 2013, by and between Master Lessor and Sublessor, and as further amended by that certain Fourth Amendment to Lease
dated as of September 16, 2015, by and between Master Lessor and Sublessor (as amended, the “Master Lease”), a redacted
copy of which is attached hereto as Exhibit B;

WHEREAS, pursuant to the Master Lease, Sublessor currently leases approximately 198,560 rentable square feet of
space in the building known as One Mercantile Place located at One Mercantile Street in Worcester, Massachusetts together
with approximately 851 parking spaces in the adjoining garage known as the Foster Street Garage (collectively, the “Master
Premises”); and

WHEREAS, Sublessee desires to sublease a portion of the Master Premises from Sublessor, and Sublessor desires to

sublease a portion of the Master Premises to Sublessee on the terms and conditions set forth herein.

NOW, THEREFORE, in consideration of the mutual covenants contained herein and for other good and valuable

consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereby agree as follows.

1.

DEFINED TERMS. All capitalized terms not otherwise defined herein shall have the same meanings as set

forth in the Master Lease.

1.1.

Building: An eight (8) story office building containing approximately one hundred ninety-eight thousand five

hundred sixty (198,560) square feet of rentable area and
located on approximately 2.312 acres of land (the “Real Property” as described in Exhibit B to the Master Lease) at 1
Mercantile Street, Worcester, Massachusetts.

1

1.2.

Sublease Premises: Approximately 26,503 square feet of rentable area located on the fourth (4th) floor of the

Building as outlined on Exhibit A attached hereto.

1.3.

Commencement Date: July 1,
2022.

1.4.

Rent Commencement Date: The earlier of (i) the date that Tenant occupies the Sublease Premises, or (ii) the
date on which Sublessee’s Work is Substantially Complete (as such term is defined in Exhibit C hereunder), but in no event
later than November 1, 2022.

1.5.

Termination Date: January 31,
2030.

1.6.

Sublease Term: Approximately seven (7) years and seven (7) months, commencing on the Commencement

Date and expiring on the Termination Date unless earlier terminated pursuant to the terms of this Sublease.

1.7.

Extension Terms:
None.

1.1.

Sublease Year: A twelve-month period from January 1 through December 31 during the Sublease Term.

However, the first Sublease Year shall run from the Commencement Date through the 31st day of December immediately
following; and the last Sublease Year shall run from the last January 1 through the date of the expiration or earlier termination
of the Term of this Sublease.

1.8.

Base Year for Operating Charges: Calendar Year 2022 (i.e. January 1,
2022-
December 31, 2022).

1.9.

Proportionate Share:
13.35%.

1.10. Permitted Use: Class A administrative office functions and ancillary uses specifically related thereto.

1.11. Building Hours: Monday through Friday, 7 a.m. to 6 p.m. and Saturday 8 a.m.

to

1 p.m.

1.12. Building Holidays: New Year’s Day, Memorial Day, Independence Day,

Labor

Day, Thanksgiving Day, the day after Thanksgiving Day, Christmas Eve and Christmas Day.

1.13. Security Deposit:
$48,588.83

1.14. Sublessor Address for

Notices:

The Paul Revere Life Insurance Company 
c/o Unum Group
1 Fountain Square
Chattanooga, TN 37402 
Attention: Corporate Real Estate

With a copy to:

2

Unum Law Department 
2211 Congress Street– B268 
Portland, ME 04122
Attn: Marybeth Fougere, Esq.

1.15. Sublessee Address For

Notices:

Mustang Bio, Inc.
377 Plantation Street
Worcester, MA 01605 
Atten: Knut Niss

With copy to:

Mustang Bio, Inc. 
377 Plantation Street
Worcester, MA 01605 
Attention: General Counsel 
mwein@mustangbio.com

1.16. Business Day: Means all days except Saturdays, Sundays, Building Holidays and other days when federal or

state banks in the Commonwealth of Massachusetts are not open for business.

2.

SUBLEASE
PREMISES.

2.1.

Sublessor hereby subleases to Sublessee, and Sublessee hereby subleases from Sublessor, the Sublease

Premises. Sublessee has been given the opportunity to inspect the Sublease Premises and accepts the Sublease Premises in
their “AS IS” and “WHERE IS,” broom clean condition on the Commencement Date. Sublessee acknowledges that Sublessor
has made no representations or warranties concerning the Sublease Premises or its fitness for Sublessee’s intended use.

2.2.

Sublessor reserves all air rights over the Sublease Premises, the use of the exterior walls, the plenum, and the

right to install, maintain, use, repair and replace pipes, ducts, conduits and wires leading through the Sublease Premises in
locations behind, above and beneath walls, dropped ceilings and flooring, respectively, which will not interfere with
Sublessee’s use thereof to serve other parts of the Building.

2.3.

Sublessor reserves the right at any time to make alterations or additions to the Building, provided that such
alterations or additions do not have a material adverse effect upon Sublessee’s access to or use of the Sublease Premises.

3.

TERM.

3

3.1.

The term of this Sublease (the “Sublease Term”) shall commence on the Commencement Date and terminate on

the Termination Date unless earlier terminated pursuant to the terms of this Sublease.

4.

MASTER
LEASE

4.1.

Sublessee hereby acknowledges and agrees that the interest and estate of the Sublessor in the Sublease

Premises is that of a lessee of a leasehold and that this Sublease is subject and subordinate to the Master Lease. Except as
otherwise provided herein or to the extent inconsistent with other specific provisions of this Sublease, Sublessee agrees to
comply with all provisions of the Master Lease as if it were the named Tenant thereunder and the Sublease Premises were the
premises leased thereunder, and not to do anything or fail to do anything to cause a breach or default under the Master Lease or
the termination thereof.

4.2.

The terms, covenants and conditions of the Master Lease insofar as they relate to the Sublease Premises are
incorporated herein by reference so that, except to the extent that they are modified by the provisions of this Sublease, each
and every term, covenant and condition of the Master Lease applicable to the Sublease Premises binding or inuring to the
benefit of the Master Lessor thereunder shall, in respect of this Sublease, bind or inure to the benefit of Sublessor, and each and
every term, covenant and condition of the Master Lease applicable to the Sublease Premises binding or inuring to the benefit
of the Sublessor as Tenant thereunder shall, in respect of this Sublease, bind or inure to the benefit of Sublessee, with the same
force and effect as if such terms, covenants and conditions were completely set forth in this Sublease. As applied to this
Sublease, the terms “Landlord,” “Tenant,” “Lease,” and “Premises” shall be deemed to refer to the Sublessor, Sublessee,
Sublease and Sublease Premises, respectively. As between the Sublessor and the Sublessee only, to the extent that the terms of
the Sublease conflict with the terms of the Master Lease, the Sublease shall control. Except as otherwise provided herein, the
Master Lease is incorporated herein by this reference, but by so doing, (i) the Sublessee shall not have derived any rights as
Tenant thereunder but rather shall derive its rights only from Sublessor as Sublessee hereunder and (ii) Sublessor shall not be
deemed to have agreed to perform any obligations of Master Lessor but rather only to use reasonable efforts to cause Master
Lessor to comply with its obligations under the Master Lease. Notwithstanding anything to the contrary contained herein the
following portions of the Master Lease are not incorporated in this Sublease: Articles 1 through 7, Section 8.1(a), the fourth
(4th) and fifth (5th) paragraphs of Section 8.1(b), Section 8.1(c), Section 9.5, Section 10.1 through 10.9, Section 10.10(a), (c)
and (d), Section 10.11 , Section 10.12, Section 11.1(a)(v), Section 11.2, Sections
11.4 through 11.8, Section 11.10, Sections 12.1 , 12.2, 12.4 through 12.7, Section 13.1(a), (b), (d), (e), (f) and (g), Section
13.3 through 13.8, Section 14.2, Section 14.3, Section 15.1(e), Article 24, Section 26.2, Section 26.3, Section 26.5, Section
26.13, Section 26.19, Section 26.20,
Section 26.21, Articles 27 through 30, Articles 32 through 34 and all Exhibits (except to the extent referenced in this Sublease
or required for interpretation of a provision of this Sublease or those provisions of the Master Lease incorporated herein),
Letter Agreement by and between One Mercantile and Sublessor dated November 11 , 2011, and Second Amendment to Lease
dated as of July 5, 2012, by and between One Mercantile and Sublessor. All Tenant indemnification obligations set forth in the
Master Lease shall, for the purposes of this Sublease, be deemed to be for the benefit of Master Lessor and Sublessor.
Sublessee shall be deemed a Transferee for purposes of Section 13.1(c) of the Master Lease.

4

4.3.

If the Master Lease shall terminate during the Sublease Term for any reason whatsoever, this Sublease shall

terminate upon such termination with the same force and effect as if such termination date had been named herein as the date
of expiration hereof.

5.

SECURITY
DEPOSIT

Sublessee  shall  deliver  the  Security  Deposit  to  Sublessor  upon  execution  of  this  Sublease.  Sublessor  shall  not  be
required to pay interest on the Security Deposit or to maintain the Security Deposit in a separate account. Within three (3) days
after  notice  of  Sublessor’s  application  of  all  or  a  portion  of  the  Security  Deposit  in  satisfaction  of  Sublessee’s  obligations
under this Sublease, Sublessee shall restore the Security Deposit to the full amount. Within approximately ninety
(90) days after the expiration or earlier termination of the Sublease Term, Sublessor shall return the Security Deposit less such
portion thereof as Sublessor may have used to satisfy Sublessee’s obligations. If Sublessor transfers the Security Deposit to a
transferee of Sublessor’s interest in the Master Lease, then such transferee (and not Sublessor) shall be liable for its return.

6.

FIXED
RENT

Sublessee shall pay “Fixed Rent” as follows:

Period

1st Sublease Year

2nd Sublease Year
3rd Sublease Year
4th Sublease Year
5th Sublease Year
6th Sublease Year
7th Sublease Year
8th Sublease Year

Yearly

$583,066.00

$596,317.50
$609,569.00
$622,820.50
$636,072.00
$649,323.50
$662,575.00
$675,826.50

Monthly

$48,588.83

$49,693.13
$50,797.42
$51,901.71
$53,006.00
$54,110.29
$55,214.58
$56,318.88

Notwithstanding the foregoing, and provided that Sublessee is not then in default under this Sublease commencing on
the Commencement Date and continuing through 11:59 P.M. EST on the last day of the twenty fourth (24th) month following
the Rent Commencement Date (the “Rent Abatement Period”), Fixed Rent shall abate with respect to the entire Sublease
Premises (the “Rent Abatement”),. During the Rent Abatement Period, however, Sublessee shall pay all Additional Rent (as
hereinafter defined), including, without limitation, electricity charges for the entire Sublease Premises and any charges for
additional parking permits. Sublessee shall make payment of Fixed Rent and Additional Rent for any fraction of a month at
the Rent Commencement Date or expiration of the Sublease Term.

7.

7.1.

ADDITIONAL
RENT

OPERATING
CHARGES

a)

If in any Sublease Year Operating Charges (as hereinafter defined) paid or incurred shall exceed

Operating Charges paid or incurred in the Base Year for Operating

5

Charges, Sublessee shall pay, as Additional Rent for such Sublease Year, Sublessee’s Proportionate Share of such excess (the
“Operating Charge Excess”).

b)

Operating Charges mean the following expenses incurred by Sublessor in its tenancy of the Building

and the Real Property: (1) electricity, water, sewer and other utility charges for service provided to the common or public
areas of the Building (the “Common Areas”), or which is not separately metered; (2) insurance premiums; (3) management
fees; (4) costs of service and maintenance contracts; (5) maintenance, repair and replacement expenses;
(6) amortization (on a straight-line basis over the useful life (not to exceed ten (10) years) of capital expenditures made by
Sublessor to improve, repair or replace the Common Areas; (7) reasonable reserves for replacements, repairs and
contingencies; (8) Sublessor’s administrative costs and overhead; and (9) any other expense incurred by Sublessor in
maintaining, repairing or operating the Building and the Real Property. Operating Charges do not include: (i) costs of initial
improvements to, or alterations of the Sublease Premises; (ii) costs to correct defects in the original design or construction of
the Building; (iii) overhead or profit, or costs in excess of competitive third-party rates, paid to affiliates of Sublessor for
services rendered to the Building;
(iv) any expenses for which Sublessor is compensated through proceeds of insurance or for which Sublessor would have been
so compensated had Sublessor maintained insurance in an amount and type required in this Sublease; (v) costs of repairs,
alterations or replacements caused by the exercise of the rights of eminent domain; (vi) the cost of any special services
rendered or costs reimbursed to another subtenant which are not generally reimbursed or rendered to other subtenants in the
Building; (vii) allowances to other subtenants for construction of tenant improvements, space planner fees, real estate brokers’
commissions; (viii) legal fees and other costs incurred in the negotiation of other subleases in the Building (including this
Sublease) or the enforcement of subleases in the Building; (ix) salaries and employment expenses of personnel above the level
of the on-site Building manager; (x) debt service payments, ground lease payments, depreciation, amortization or other similar
noncash accounting charges; (xi) any cost or expense for which Sublessor is paid or reimbursed by or is legally entitled to
payment or reimbursement from any subtenant of the Building (other than from subtenants paying their share of Operating
Charges) or any other party; (xii) any expenses for repairs or maintenance which are covered by warranties; (xiii) costs
incurred due to the violation by the Master Lessor or Sublessor of any law, code, regulation, ordinance or the like, which cost
would not have been incurred but for such violation; (xiv) the cost of acquiring or leasing paintings or other objects of art for
the Building; and (xv) real estate taxes, which are deemed included in Fixed Rent.

c)

At the commencement of the Sublease Term and each Sublease Year thereafter, Sublessor shall submit

a written statement indicating the amount of Operating Charges and Operating Charge Excess that Sublessor reasonably
expects to be incurred during such Sublease Year. Sublessee shall pay to Sublessor on the first day of each month after receipt
of such statement, until Sublessee’s receipt of a succeeding statement, an amount equal to one- twelfth (1/12th) of such
Operating Charge Excess. Sublessor reserves the right to submit a revised statement if Sublessor expects Operating Charges to
differ from the prior estimation. If a statement is submitted after the beginning of a Sublease Year, then the first payment
thereafter shall be adjusted to account for any underpayment or overpayment based on the prior statement and subsequent
payments shall be based on the latest statement. If during all or any portion of any calendar year during the Sublease Term, the
Building is not one hundred percent (100%) occupied by tenants, Sublessor may elect to make an appropriate adjustment of
Operating

6

Charges for such calendar year, to determine the Operating Charges that would have been paid or incurred by Sublessor had
the Building been one hundred percent (100%) occupied by tenants for the entire year and the amount so determined shall be
deemed to be the Operating Charges for such year.

d)

Within approximately one hundred twenty (120) days after each Sublease Year, Sublessor shall submit a

statement indicating (1) Sublessee’s Operating Charge Excess
incurred during such Sublease Year, and (2) the sum of Sublessee’s estimated payments for such Sublease Year. If such
statement indicates that such sum exceeds Sublessee’s actual obligation, then Sublessee shall deduct the overpayment from its
next payment(s) pursuant to this Section. If such statement indicates that Sublessee’s actual obligation exceeds such sum, then
Sublessee shall pay the excess. If Sublessee does not notify Sublessor in writing of any objection to such statement within
thirty (30) days after receipt, then Sublessee shall be deemed to have waived such objection.

e)

If the Sublease Term commences or expires on a day other than January 1 or December 31,

respectively, then Sublessee’s liability for Operating Charges incurred during the applicable Sublease Year shall be
proportionately reduced based on the number of days in the Sublease Term falling within such Sublease Year.

f)

Within sixty (60) days after Sublessor furnishes to Sublessee the statement of Operating Charges

referenced in subsection (d) above (the “Audit Election Period”), Sublessee shall have the right, at its sole cost and expense,
during Sublessor’s normal business hours, to audit Sublessor’s Operating Charges for the previous calendar year and the Base
Year only, subject to the following conditions: (1) there is no uncured Event of Default under this Sublease; (2) the audit shall
be prepared by an independent certified public accounting firm of recognized national standing; (3) in no event shall any audit
be performed by a firm retained on a “contingency fee” basis; (4) the audit shall commence within thirty (30) days after
Sublessor makes Sublessor’s books and records available to Sublessee’s auditor and shall conclude within sixty (60) days after
commencement; (5) the audit shall be conducted where Sublessor maintains its books and records and shall not unreasonably
interfere with the conduct of Sublessor’s business; and (6) Sublessee and its accounting firm shall treat any audit in a
confidential manner and shall each execute Sublessor’s confidentiality agreement for Sublessor’s benefit before commencing
the audit. Sublessee shall deliver a copy of such audit to Sublessor within five (5) Business Days of receipt by Sublessee. This
subsection shall not be construed to limit, suspend, or abate Sublessee’s obligation to pay Rent when due, including the
estimated Operating Charge Excess. After verification, Sublessor shall credit any overpayment determined by the audit report
against the next Rent due and owing by Sublessee or, if no further Rent is due, refund such overpayment directly to Sublessee
within thirty (30) days of determination. Sublessee shall pay Sublessor any underpayment determined by the audit report
within thirty (30) days of determination. The foregoing obligations shall survive the expiration or earlier termination of the
Sublease. If Sublessee does not give written notice of its election to audit during the Audit
Election Period, Sublessor’s statement of Operating Charges for the applicable calendar year shall be deemed approved for all
purposes, and Sublessee shall have no further right to review or contest the same.

7.2.

All sums other than Fixed Rent, including, without limitation, the amounts due under Sections 7 and 8 of this

Sublease, late charges, damages and interest and other costs

7

relating to Sublessee’s failure to perform any of its obligations under the Sublease shall be
deemed “Additional Rent”. Fixed Rent and Additional Rent are collectively referred to herein as “Rent”.

8.

UTILITIES AND
SECURITY

8.1.

Sublessor shall supply water, sewer, electricity, heating and air conditioning service to the Sublease Premises.
Electricity to the Sublease Premises (lights and plugs) will be submetered and Sublessee will pay to Sublessor, as Additional
Rent, its share of electricity charges as shown on the submeter within fifteen (15) days of receipt of Sublessor’s invoice
therefor; provided, Sublessee’s share of charges for electricity supplied to the Sublease Premises during normal business hours
shall not exceed $1.75 per rentable square foot of the Sublease Premises. If Sublessee desires heating or air-conditioning
service at a time other than during the Building’s normal business hours, which are 7:00 a.m. to 6:00 p.m. on Business Days
and 8:00
a.m. to 1:00 p.m. on Saturdays, then Sublessee shall pay to Sublessor the cost of such services on a floor-by-floor basis as
Additional Rent within fifteen (15) days after receipt of Sublessor’s
invoice therefor. The rate for heating and air conditioning if used outside of the Building’s normal business hours is currently
$100.00 per hour, subject to reasonable increases by Sublessor from time to time.

8.2.

Sublessee shall at all times comply with the rules and regulations of the utility company supplying electricity to
the Building. Sublessee shall not install any electrical equipment which would exceed the capacity of the Building’s electrical
equipment.

8.3.

Sublessee shall cooperate fully in Sublessor’s efforts to maintain access control to the Building and shall follow
all regulations promulgated by Sublessor with respect thereto. Sublessor shall permit Sublessee to utilize the Building security
systems to control access to the Sublease Premises to provide access to the Sublease Premises from the Building and the
exterior solely for Sublessee’s permitted employees, agents, officers, directors, contractors and escorted guests and Invitees
(hereinafter defined); provided, however, that Sublessee shall pay the cost of all key cards issued to Sublessee at the then-
current rate charged by Sublessor.

9.

USE OF SUBLEASE
PREMISES

9.1.
purpose or purposes.

Sublessee shall have the right to use and occupy the Sublease Premises for the Permitted Use and for no other

9.2.

Sublessee shall not permit any use of the Sublease Premises which shall make voidable any insurance upon the
Sublease Premises or upon the property of which the Sublease Premises are a part. The Sublessee shall on demand reimburse
the Sublessor for all extra
insurance premiums incurred by Sublessor solely and directly caused by Sublessee’s specialized use of the Sublease Premises.
The Sublessee shall secure all necessary permits and licenses for the lawful operation of said business and shall provide copies
of such licenses and permits to Sublessor.

9.3.

Sublessee shall at all times protect and save harmless the Master Lessor and the Sublessor from the imposition

of any liens, taxes or other charges that may be imposed upon the Sublease Premises or upon other property of which the
Sublease Premises are a part, by reason of the occupancy and use by Sublessee of the Sublease Premises.

8

9.4.

Subject to applicable Requirements (as defined below), Sublessee shall have access to and the right to the use of

the Sublease Premises on a 24 hour per day, 7 day per week, 365 day per year basis.

9.5.

Sublessee shall not use the Sublease Premises in a manner that would (a) violate the terms of any occupancy or

use permit, (b) impair or interfere with any Building system or facility, or (c) adversely affect the Building’s appearance,
character or reputation. Sublessee shall not use the Sublease Premises in any manner that will cause the Building, the Real
Property or any part thereof not to comply with Sublessor’s sustainability practices and its Silver
certification from the United States Green Building Council’s Leadership in Energy and Environmental Design (“LEED”)
rating system.

9.6.

Subject to Section 12 of this Sublease, Sublessee shall be responsible for the cost of any alterations, additions,

or changes to the Building or the Garage required pursuant to the Americans With Disabilities Act of 1990, and any
amendments thereto (the “ADA”) as a result of the Permitted Use, Sublessee’s Work or any Alterations made by Sublessee to
the Sublease Premises.

9.7.

Sublessee shall require any truck or other vehicle serving Sublessee to use the service area designated by

Sublessor. Sublessee shall cause any such vehicle promptly to be loaded or unloaded and removed from such area.
Immediately after using such service area, Sublessee shall remove any debris and clean such area to its prior condition.
Sublessee’s use of such area shall comply with all rules and regulations governing such use as may be provided to Sublessee.
Sublessee’s use of such area shall not unreasonably impede the use thereof by others including Sublessor.

9.8.

Sublessor shall provide Sublessee with non-exclusive access to the fitness center located in the Building for
Sublessee’s employees at no additional cost; provided, however, that such access shall be contingent upon such employees
signing the standard waiver and any other documents requested by Sublessor for use of the fitness center. In the event that the
fitness center is renovated during the Sublease Term, Sublessee shall, upon completion of such renovation, commence paying
to Sublessor each month in advance as Additional Rent Sublessor’s then-current per-person charge applied to all tenants of the
Building for use of the fitness center.

9.9.

Sublessee shall pay timely any business, rent or other tax or governmental fee that is now or hereafter assessed
or imposed upon Sublessee’s use or occupancy of the Sublease Premises, the conduct of Sublessee’s business in the Sublease
Premises or Sublessee’s fixtures, furnishings, inventory or personal property. If any such tax or fee is imposed upon Sublessor
or Sublessor is responsible for collection or payment thereof, then Sublessee shall pay to Sublessor the amount of such tax or
fee on demand.

9.10. Sublessee’s use of the Sublease Premises and the Common Areas shall comply in all respects with the rules and
regulations set forth in Exhibit D attached hereto, as such rules and regulations may be modified or restated by Sublessor from
time to time (collectively, the “Requirements”).

9

9.11. Sublessee shall, at its expense, comply and cause the Sublease Premises to comply with all applicable

Requirements, subject to the provisions of Section 9.6 of this Sublease.

10.

SUBLESSEE’S
INSURANCE

Throughout the Sublease Term, Sublessee shall maintain with respect to the Sublease Premises commercial general

liability insurance, workers’ compensation insurance and “all-risk” property insurance in the amounts and on the terms stated
in the following sections of the Master Lease: Article 11, subsection 11.1(a), subsections (i), (ii), (iii), (iv) (substituting the
Sublease Premises for the Real Property), and (vi). Such insurance shall name Master Lessor and Sublessor as additional
insureds. In addition, Sublessee agrees to comply with the remaining provisions of Article 11 of the Master Lease in the same
manner as if it was the Tenant thereunder and shall provide both the Master Lessor and the Sublessor with evidence of such
compliance in the form and manner set forth therein. Sublessee shall provide the waiver of subrogation set forth in Section
11.3 of the Master Lease to both Sublessor and Master Lessor."

11. MAINTENANCE AND

REPAIRS

11.1. Sublessor shall make repairs which Sublessor deems necessary to the structure and exterior (including access

doors and windows but excluding interior doors and glass) of the Sublease Premises; provided Sublessor has actual knowledge
of the necessity for such repair in accordance with its obligations under the Master Lease. In addition, Sublessor shall provide
cleaning service and trash removal for the Sublease Premises Monday through Friday, excluding Building Holidays.

11.2. Except as otherwise provided in Section 11.1, Sublessee shall maintain the Sublease Premises and all fixtures
and equipment located therein or exclusively serving the Sublease Premises in clean, safe and sanitary condition, take good
care thereof, make all repairs and replacements thereto and suffer no waste or injury thereto, and Sublessee shall promptly
make all repairs, perform all maintenance, and make all replacements in and to the Sublease Premises that are necessary or
desirable to keep the Sublease Premises in first class condition and repair, in a safe and tenantable condition, and otherwise in
accordance with the requirements of this Sublease. Without limitation of the generality of the foregoing, Sublessee shall
promptly make all repairs and replacements to (a) any pipes, lines, ducts, wires or conduits exclusively serving the Sublease
Premises, (b) Sublessee’s signs, (c) any non-building system heating, air conditioning, ventilating, electrical or plumbing
equipment installed in or exclusively serving the Sublease Premises, (d) all interior glass and doors, and (e) any other
mechanical system exclusively serving the Sublease Premises. Sublessee shall give to Sublessor prompt written notice of any
damage to the Sublease Premises, the Building or any part thereof. Sublessee shall maintain a maintenance contract on the
heating, ventilation and air conditioning equipment and systems exclusively serving the Sublease Premises with a contractor
approved by Sublessor, and shall provide a copy of such contract to Sublessor upon request. Sublessor reserves the right to
establish a regular inspection and maintenance program for all heating, ventilation and air conditioning equipment maintained
by Sublessee and to provide all necessary or appropriate
maintenance and repairs at Sublessee’s expense. Sublessee shall install and maintain fire extinguishers and other fire
protection devices (other than sprinklers) as may be required or recommended by Master Lessor or any governmental
authority or insurance underwriter.

10

Sublessee shall operate its heating and air conditioning systems servicing the Sublease Premises so as to adequately heat or
cool the Sublease Premises. All damage to the Sublease Premises or to any other part of the Building or the Real Property
caused by any act or omission of any invitee, agent, employee, subtenant, assignee, contractor, client, family member,
licensee, concessionaire, customer or guest of Sublessee (collectively “Invitees”) or Sublessee shall be repaired by Sublessee,
except that Sublessor shall have the right to make any such repair at Sublessee’s expense.

Notwithstanding anything to the contrary contained in this Article 11, Sublessor may, at Sublessor’s election, perform
any of Sublessee’s maintenance, repair and/or replacement obligations set forth in this Section 11 with respect to any fixtures
or equipment located outside of the Sublease Premises on Sublessee’s behalf, and Sublessee shall reimburse Sublessor for the
cost of any such maintenance, repair or replacement within thirty (30) days of Sublessor’s written demand therefor.

11.3. Sublessee shall cause its operation and maintenance of the Sublease Premises to comply with the standards,

requirements, guidelines and energy conservation measures set forth in Exhibit E attached hereto.

12.

ALTERATIONS AND
ADDITIONS

12.1. The original improvement of the Sublease Premises shall be accomplished in accordance with the Work Letter
attached hereto as Exhibit C. Sublessor will deliver the Sublease Premises to Sublessee in As-Is, Where-Is condition, with all
base building systems in working condition. Sublessor is under no obligation to make any alterations, decorations, additions,
improvements or other changes (collectively “Alterations”) in or to the Sublease Premises.

12.2. Sublessee shall not make or permit anyone to make any Alteration in or to the Sublease Premises or the
Building without Sublessor’s prior written consent, which consent shall not be unreasonably withheld, conditioned or delayed.
Any Alteration made by Sublessee shall be made: (a) in a good, workmanlike, first-class and prompt manner; (b) using new
materials only; (c) by a contractor, on days and at times and under the supervision of an architect approved in writing by
Sublessor; (d) in accordance with plans and specifications prepared by an engineer or architect approved by Sublessor and
reviewed (at Sublessor’s standard charge) by Sublessor;
(e) in accordance with the Requirements, the requirements of any firm insuring the Building and the Building standards; (f)
after  obtaining  a  worker’s  compensation  insurance  policy  approved  in  writing  by  Sublessor  and  any  bonds  required  by
Sublessor; (g) after delivering to Sublessor
written, unconditional waivers of mechanics’ and materialmen’s liens against the Sublease Premises and the Building from all
proposed contractors, subcontractors, laborers and material suppliers; and (h) with respect to electrical and mechanical work,
by a contractor designated by Sublessor. Subsections (c), (d), (f), and (g) of the immediately foregoing sentence shall only be
applicable in the event that an Alteration requires a building permit. If a lien (or a petition to establish a lien) is filed in
connection with any Alteration, then such lien (or petition) shall be discharged by Sublessee at Sublessee’s expense within ten
(10) days thereafter by the payment
thereof or filing of a bond acceptable to Sublessor. Sublessor’s consent to an Alteration shall be deemed not to constitute
Sublessor’s consent to subjecting its interest in the Sublease Premises or the Building to liens which may be filed in
connection therewith. Promptly after the completion

11

of an Alteration, Sublessee at its expense shall deliver to Sublessor three (3) sets of accurate as- built drawings showing such
Alteration.

12.3.

If an Alteration is made without Sublessor’s prior written consent, then Sublessor shall have the right at

Sublessee’s expense to remove such Alteration and restore the Sublease Premises and the Building to their condition
immediately prior thereto or to require Sublessee to do the same. All Alterations to the Sublease Premises or the Building
made by either party shall immediately become Sublessor’s property and shall be surrendered with the Sublease Premises at
the expiration or earlier termination of the Sublease Term, except that (a) Sublessee shall have the right to remove, prior to the
expiration or earlier termination of the Sublease Term, movable furniture, movable furnishings and movable trade fixtures
installed in the Sublease Premises by Sublessee solely at Sublessee’s expense, and (b) Sublessee shall be required to remove
all Alterations to the Sublease Premises or the Building which Sublessor designates in writing for removal. Movable furniture,
furnishings and trade fixtures shall be deemed to exclude without limitation any item the removal of which might cause
damage to the Sublease Premises or the Building or which would normally be removed from the Sublease Premises with the
assistance of any tool or machinery other than a dolly. Sublessor shall have the right to repair at Sublessee’s expense any
damage to the Sublease Premises or the Building caused by such removal or to require Sublessee to do the same. If any such
item is not removed prior to the expiration or earlier termination of the Sublease Term, then such item shall become
Sublessor’s property and shall be surrendered with the Sublease Premises as a part thereof; provided, however, that Sublessor
shall have the right to remove such item from the Sublease Premises at Sublessee’s expense.

12.4. Sublessee shall not employ, or permit the employment of, any contractor, mechanic or laborer, or permit any

materials to be delivered to or used in the Sublease Premises or the Building if, in Sublessee’s reasonable judgment, such
employment, delivery or use will interfere with or obstruct or cause any conflict with other contractors, mechanics or laborers
engaged in the construction, maintenance or operation of the Real Property by Sublessor, Master Lessor or others. If such
interference or conflict occurs, then upon Sublessor’s request, Sublessee shall immediately cause all contractors, mechanics or
laborers causing such interference or conflict to leave the Real Property.

12.5. The approval of plans, or consent by Sublessor to the making of any Alterations, shall not constitute Sublessor’s

representation that such plans or Alterations comply with any Requirements. Sublessor shall not be liable to Sublessee or any
other party in connection with Sublessor’s approval of any plans, or Sublessor’s consent to Sublessee performing any
Alterations. If any Alterations made by or on behalf of Sublessee require Sublessor to make any alterations or improvements to
any part of the Real Property in order to comply with any Requirements, Sublessee shall pay, within thirty (30) days following
completion of such alterations or improvements and delivery of an itemized statement or invoice from Sublessor, as Additional
Rent, all reasonable, out-of-pocket costs and expenses incurred by Sublessor in connection with such alterations or
improvements.

12.6.

In the case of any Alteration requiring Master Lessor approval under the Master Lease, in addition to

Sublessor’s prior written consent, Sublessee may not commence such Alteration until Master Lessor has approved the same in
writing.

12

13.

SIGNS

13.1. Notwithstanding anything to the contrary contained the Master Lease, as incorporated herein, Sublessee shall

not have the right to erect any signs on the Sublease Premises, the property of which the Sublease Premises are a part, or in the
windows of the Sublease Premises without Sublessor’s prior written consent, which shall not be unreasonably withheld,
delayed or conditioned (provided that it shall not be unreasonable for Sublessor to withhold consent to the installation of any
sign the removal of which will, in Sublessor’s sole judgment, unduly damage the Sublease Premises or the Building). All signs
shall be in compliance with all applicable Requirements. Sublessee shall install a professionally lettered name sign on each
service door. Sublessee shall insure, maintain in first class order, good condition and repair each sign and lettering used by
Sublessee. Upon the expiration or earlier termination of the Sublease Term, Sublessee shall remove any sign and repair any
damage attributable to such sign or its removal. Notwithstanding the foregoing, Sublessor may elect, in Sublessor’s sole
discretion, to install and/or remove any of Sublessee’s approved signage at Sublessee’s sole cost and expense.

13.2. Sublessor shall provide, at Sublessor’s sole cost and expense, Sublessee with Building standard signage (a) in
the main lobby Building directory, and (b) at the entry way of the Sublease Premises, as well as Building standard directional
signage on the floor on which the Sublease Premises are located. Any logo or detail approved by Sublessor for the entry way
signage shall be at Sublessee’s sole cost and expense.

14.

ASSIGNMENT AND
SUBLEASING

14.1. Sublessee shall not assign or sub-sublease the whole or any part of the Sublease Premises without (a)
Sublessor’s prior written consent, which shall not be unreasonably withheld, conditioned or delayed, and (b) Master Lessor’s
consent which shall be governed by the Master Lease. Notwithstanding such consent, Sublessee shall remain liable to
Sublessor for the payment of all Rent and for the full performance of the covenants and conditions of this Sublease.

14.2.

In addition to Sublessor’s right to approve of any sub-sublessee or assignee, Sublessor shall have the option, in

its sole discretion, in the event of a proposed sub-subleasing or assignment, to terminate this Sublease, or in the case of a
proposed sub-subleasing of less than the entire Sublease Premises, to recapture the portion of the Sublease Premises to be sub-
sublet, as of the date the sub-sublease or assignment is to be effective. The option shall be exercised, if at all, by Sublessor
giving Sublessee written notice within thirty (30) days following Sublessor’s receipt of Sublessee’s written request for consent
pursuant to Section 14.1. If this Sublease shall be terminated with respect to the entire Sublease Premises pursuant to this
Section, the Sublease Term shall end on the date stated in Sublessee’s notice as the effective date of the sub-sublease or
assignment as if that date had been originally fixed in this Sublease for the expiration of the Sublease Term. If Sublessor
recaptures under this Section only a portion of the Sublease Premises, the Rent to be paid from time to time during the
unexpired Sublease Term shall abate proportionately based on the proportion by which the approximate square footage of the
remaining portion of the Sublease Premises shall be less than that of the Sublease Premises as of the date immediately prior to
such recapture. Sublessee shall, at Sublessee’s own cost and expense, discharge in full any outstanding commission obligation
which may be due and owing

13

as a result of any proposed assignment or sub-subletting, whether or not the Sublease Premises are recaptured pursuant to this
Section 14.2 and rented by Sublessor to the proposed sub- sublessee or any other sublessee.

14.3.

In the event that Sublessee sells, sublets, assigns or transfers this Sublease, Sublessee shall pay to Sublessor as

Additional Rent an amount equal to fifty percent (50%) of any Increased Rent (as hereinafter defined), less the Costs
Component (as hereinafter defined), when and as such Increased Rent is received by Sublessee. As used in this Section,
“Increased Rent” shall mean the excess of (i) all rent and other consideration which Sublessee is entitled to receive by reason
of any sale, sub-sublease, assignment or other transfer of this Sublease, over
(ii) the rent otherwise payable by Sublessee under this Sublease at such time. For purposes of the foregoing, any consideration
received by Sublessee in form other than cash shall be valued at its fair market value as determined by Sublessor in good faith.
The “Costs Component” is the reasonable costs incurred by Sublessee in entering into the transaction, including without
limitation, costs for leasing commissions, attorneys’ fees, marketing and advertising expenses, tenant improvements, free rent
and other tenant concessions in connection with such sub- sublease, assignment or other transfer, all of which may be deducted
prior to paying any Increased Rent hereunder.

15.

SUBORDINATION

This Sublease shall be subject and subordinate to any and all mortgages, deeds of trust and other instruments in the
nature of a mortgage, now or at any time hereafter, which are or shall be a lien or liens on the Sublease Premises or on the
property of which the Sublease Premises are a part, whether granted by Sublessor or Master Lessor as mortgagor, and the
Sublessee shall, when requested, promptly execute and deliver such written instruments as shall be necessary to show the
subordination of this Sublease to said mortgage, deeds of trust or other such instruments in the nature of a mortgage.

16.

SUBLESSOR’S
ACCESS

The Sublessor or agents of the Sublessor may, at reasonable times and upon not less than twenty-four (24) hours prior
notice, enter to view the Sublease Premises and make repairs and alterations that Sublessor is obligated to perform under this
Sublease or the Master Lease and may show the Sublease Premises to others in the presence of Sublessee or its agent.
Sublessor shall use commercially reasonable efforts to minimize disruption to Sublessee’s business caused by such access.

17. MASTER LESSOR’S

ACCESS

The Sublessee shall provide Master Lessor with access to the Sublease Premises as provided in Article 14 of the Master

Lease, as incorporated herein.

18.

INDEMNIFICATION OF MASTER LESSOR AND
SUBLESSOR

18.1. The provisions of Section 25.1, 25.2 and 25.3 of the Master Lease are incorporated herein; provided, however,

that the references to “Landlord” in the definition of Indemnitees shall be deemed to include both Master Lessor and
Sublessor, and references to the Premises shall be deemed to refer to the Sublease Premises, further provided, however, that
the

14

indemnities set forth in Section 25.1 shall not include any claims arising from the gross negligence or willful misconduct of
Sublessor and the indemnities set forth in Section 25.2 shall not include any claims arising from the gross negligence or
willful misconduct of Sublessee.
The provisions of this Section 18.1 shall survive the expiration or earlier termination of this Sublease.

18.2.

Intentionally
Omitted.

18.3. Sublessor, its officers, directors, employees and agents shall not be liable to Sublessee or any other person or

entity for any damage (including indirect and consequential damage), injury, loss or claim (including claims for the
interruption of or loss to business) based on or arising out of any cause whatsoever, including without limitation: repair to any
portion of the Sublease Premises or the Building; interruption in the use of the Sublease Premises or any equipment therein;
accident or damage resulting from any use or operation (by Sublessor, Sublessee or any other person or entity) of elevators or
heating, cooling, electrical, sewerage or plumbing equipment; termination of this Sublease by reason of damage to or
condemnation of the Sublease Premises or the Building; fire, robbery, theft, vandalism, mysterious disappearance or any other
casualty; actions of any other tenant of the Building or other person or entity; failure or inability to furnish or interruption in
any utility or service specified in this Sublease; and leakage in any part of the Sublease Premises or the Building. If a condition
exists which may be the basis of a claim of constructive eviction, then Sublessee shall give Sublessor written notice thereof
and a reasonable opportunity to correct such condition, and in the interim Sublessee shall not claim that it has been
constructively evicted or is entitled to any abatement of Rent. Any property placed by Sublessee in or about the Sublessee
Premises or the Building shall be at the sole risk of Sublessee, and Sublessor shall not in any manner be responsible therefor.
For purposes of this Section, the term “Building” shall be deemed to include the Real Property. Notwithstanding the
foregoing, nothing in this Section 18 shall limit the Sublessor’s obligations under Sections 8.1 and 11 hereof.

18.4. The provisions of this Section 18 shall survive the expiration or earlier termination of this Sublease.

19.

FIRE, CASUALTY AND EMINENT
DOMAIN

19.1.

If the Sublease Premises are rendered totally or partially inaccessible or unusable by fire or other casualty, then
Sublessor shall diligently restore the Sublease Premises and the Building to substantially the same condition they were in prior
to such casualty in accordance with Section 11.4 of the Master Lease; provided, however that if in Sublessor’s judgment such
restoration cannot be completed within ninety (90) days after the occurrence of such casualty (taking into account the time
needed for effecting a settlement with any insurance company, removal of debris, preparation of plans and issuance of all
required governmental permits), then Sublessor shall have the right to terminate the Sublease Term as of the sixtieth (60th)
day after such casualty by giving written notice to Sublessee. If this Sublease is not terminated pursuant to this Section, then
until such restoration of the Sublease Premises are substantially complete Sublessee shall be required to pay the Rent for only
the portion of the Sublease Premises that in Sublessee’s judgment is usable while such restoration is being made, except that if
such casualty was caused by the act or omission of Sublessee or an employee, guest, agent or Invitee of Sublessee, then
Sublessee shall not be entitled to any Rent reduction. After receipt of the

15

insurance proceeds (including proceeds of any insurance maintained by Sublessee), Sublessor shall restore the Sublease
Premises and the Building, except that (a) if such casualty was caused by the act or omission of Sublessee or an employee,
guest, agent or Invitee of Sublessee, then Sublessee shall pay the amount by which such expenses exceed any property
insurance proceeds actually received by Sublessor on account of such casualty, and (b) Sublessor shall not be required to repair
or restore any Alteration made by Sublessee or any of Sublessee’s trade fixtures, furnishings, equipment or personal property.
Anything herein to the contrary notwithstanding, Sublessor shall have the right to terminate this Sublease if (1) insurance
proceeds are insufficient to pay the full cost of such restoration, (2) any mortgage holder does not make such proceeds
available for such restoration, (3) zoning or other laws do not permit such restoration, or (4) restoration costs exceed twenty-
five percent (25%) of the Building’s replacement value.

19.2.

If one-third or more of the Sublease Premises or occupancy thereof is condemned or sold under threat of

condemnation (collectively “condemned”), then this Sublease shall
terminate on the day prior to the date title vests in the condemnor (the “Vesting Date”). If less than such one-third is
condemned, then this Sublease shall continue in full force and effect as to the part of the Sublease Premises not condemned,
except that Rent shall be reduced proportionately as of the Vesting Date.

19.3. All awards, damages and compensation paid on account of such condemnation shall belong to Master Lessor in

accordance with Section 12.3 of the Master Lease. Sublessee assigns to Sublessor and Master Lessor all rights thereto.
Sublessee shall not make any claim against Master Lessor or Sublessor or the condemnor for any portion thereof attributable
to damage to the Sublease Premises, value of the unexpired portion of the Sublease Term, loss of profits or goodwill,
leasehold improvements or severance damages. The foregoing shall not prevent Sublessee from pursuing a separate claim
against the condemnor for the value of movable furnishings and movable trade fixtures installed in the Sublease Premises
solely at Sublessee’s expense and relocation expenses, provided that such claim in no way diminishes any award, damages or
compensation payable to Sublessor or Master Lessor.

20.

DEFAULT

20.1. Any Event of Default by Sublessee pursuant to Article 15 of the Master Lease, as incorporated herein, shall be
an Event of Default by Sublessee hereunder except that all references to “Tenant Obligations Guarantor” shall have no force
and effect. Further, in incorporating Article 15 of the Master Lease as aforesaid, the provisions of Section 15.1(a) of the
Master Lease are hereby modified such that the phrase “Fixed Rent, the TIF Payments or Tenant’s Tax Payments” shall be
deleted and the word “Rent” substituted therefor.

20.2. Sublessor shall in no event be in default under this Sublease unless Sublessor shall neglect or fail to perform any

of its obligations hereunder and shall fail to remedy the same within thirty (30) days after notice to Sublessor specifying such
neglect or failure, or if such failure is of such a nature that Sublessor cannot reasonably remedy the same within such thirty
(30) day period, Sublessor shall fail to commence promptly (and in any event within such thirty
(30) day period) to remedy the same and to prosecute such remedy to completion with diligence and continuity. In the event of
a default by Sublessor hereunder which continues uncured

16

beyond the period described in the preceding sentence, Sublessee shall be entitled to pursue any available legal remedy.

21.

SUBLESSOR’S
REMEDIES

In the event of any Event of Default of this Sublease by Sublessee, Sublessor may exercise any of the rights and

remedies set forth in Article 15 of the Master Lease, as incorporated herein, in accordance with the terms thereof.

In addition to Sublessor’s remedies set forth above, Sublessor’s obligation to pay the Allowance and Sublessee’s right

to the Rent Abatement shall be deemed conditioned upon Sublessee’s full and faithful performance of all of the terms,
covenants and conditions of this Sublease to be performed by Sublessee during the Sublease Term. Upon the occurrence of an
Event of Default, Sublessor’s obligation to pay the Allowance and Sublessee’s right to the Rent Abatement shall automatically
be deemed void and of no further force or effect, and the
unamortized portion of (a) the Rent Abatement, and (b) the Allowance paid by Sublessor shall be immediately due and
payable by Sublessee to Sublessor, and recoverable by Sublessor as
Additional Rent due under this Sublease. The “unamortized portion” shall be calculated to equal the amount of principal which
would remain unpaid as of the date of the Event of Default with respect to a loan in an original principal amount equal to the
Rent Abatement and the Allowance and which is repaid in equal monthly installments of principal and interest on a direct
reduction over the Sublease Term with interest at the rate described in Section 22.

22.

SUBLESSOR’S RIGHT TO REMEDY SUBLESSEE’S
DEFAULT

If Sublessee fails to observe or perform any of the Sublessee’s covenants, agreements, or obligations required of
Sublessee under this Sublease, and such failure shall not be cured within the applicable grace period as provided in Section 20
hereof, the Sublessor, without being under any obligation to do so and without thereby waiving such default, may remedy such
default for the account and at the expense of the Sublessee. If the Sublessor makes any expenditures or incurs any obligations
for the payment of money in connection therewith, including but not
limited to, reasonable attorneys’ fees in instituting, prosecuting or defending any action or proceeding, such sums paid or the
cost of such obligations performed, with interest at the rate of five percent (5%) per annum over the base rate in effect from
time to time at Bank of America shall be paid to the Sublessor by the Sublessee as Additional Rent.

23.

SURRENDER;
HOLDOVER

The Sublessee shall at the expiration or earlier termination of this Sublease surrender the Sublease Premises broom

clean and in a condition equal to or better than their condition on the Commencement Date, except for ordinary wear and tear.
Sublessee shall remove all Sublessee’s goods and effects from the Sublease Premises (including, without hereby limiting the
generality of the foregoing, all signs and lettering affixed or painted by the Sublessee, either inside or outside the Sublease
Premises). Sublessee shall deliver to the Sublessor the Sublease Premises and all keys, locks thereto, and all fixtures connected
therewith and, to the extent restoration is not required by Sublessor as provided herein, all alterations and additions made to or
upon the Sublease Premises, in good condition, damage by fire or other casualty only excepted. In the event of the Sublessee’s
failure to remove any of Sublessee’s property from the Sublease

17

Premises, Sublessor is hereby authorized, without liability to Sublessee for loss or damage thereto, and at the sole risk of
Sublessee, to remove and store any of the property at Sublessee’s expense, or to retain same under Sublessor’s control or to
sell at public or private sale, without notice, any or all of the property not so removed and to apply the net proceeds of such
sale to the payment of any sum due hereunder, or to destroy such property.

Any holding over by Sublessee after the expiration of the Sublease Term shall be treated as a tenancy at sufferance in

accordance with the terms of Section 18.2 of the Master Lease.
Sublessee shall also pay to Sublessor (i) all damages, direct and indirect, sustained by reason of any such holding over,
including, without limitation, loss of a sublessee, and (ii) all charges payable by Sublessor to Master Lessor as a result of such
holding over.

24.

LATE CHARGE AND
INTEREST

If any sums due by Sublessee to Sublessor hereunder are not paid within ten (10) Business Days after the due date,

Sublessee shall pay to Sublessor, in addition to any charges in Section 22, a late charge equal to five percent (5%) of the
overdue amount for each such late payment.

25.

FORCE
MAJEURE

In the event that the Sublessor or Sublessee is prevented from performing any covenant hereunder by reason of any

cause reasonably beyond the control of such party, the party prevented from performing shall not be liable to the other party
therefor nor shall the other party be entitled to any abatement or reduction of any payment due or owing by reason thereof.

26.

RELATION TO MASTER
LEASE

All obligations of Sublessor hereunder are predicated upon Sublessor’s rights under the Master Lease. Should the

Master Lease be terminated for any reason or Sublessor’s rights
thereunder be abrogated, delayed or restricted in a manner which adversely affects Sublessee’s rights hereunder, Sublessor
shall have no liability to Sublessee therefor.

27.

LIABILITY OF
PARTIES

27.1. The obligations of the Sublessor shall be binding upon the Sublessor’s interest in the Master Lease, but not

upon other assets of the Sublessor, and no individual officer, director, employee or agent of the Sublessor shall be personally
liable for performance of the Sublessor’s obligations hereunder. Sublessor shall bear no liability for any loss of personal
property or injury to the person or property of Sublessee, its employees, invitees, agents or any other person coming on to the
Sublease Premises or the property of which the Sublease Premises are a part due in whole or in part to the presence of
Sublessee therein.

27.2. No individual, officer, member, director, employee or agent of the Sublessee shall be personally liable for the

performance of the Sublessee’s obligations hereunder.

28.

NOTICE

18

All notices or other communications hereunder shall be in writing and delivered in the manner provided in Article 22 of

the Master Lease, except that the addresses for the Sublessor and the Sublessee shall be as follows:

(a)

If to Sublessor,
to

The Paul Revere Life Insurance Company 
c/o Unum Group
1 Fountain Square
Chattanooga, TN 37402 
Attention: Corporate Real Estate.

With a copy to:

Unum Law Department 
2211 Congress Street– B268 
Portland, ME 04122
Attn: Marybeth Fougere, Esq.

(b)

If to Sublessee,
to

Mustang Bio, Inc. 
377 Plantation Street
Worcester, MA 01605 
Atten: Knut Niss

With copy to (as of the Commencement Date):

Mustang Bio, Inc.
Atten: General Counsel
1 Mercantile Street, Suite 400
Worcester, MA 01608

29.

HAZARDOUS
MATERIALS

Sublessee shall comply with the provisions of Section 8.1(b) of the Master Lease in the same manner as if it were
Tenant thereunder and further agrees to indemnify, defend upon demand with counsel reasonably acceptable to Master Lessor
and Sublessor, and hold Master Lessor and Sublessor harmless from and against, any liabilities, losses, claims, damages,
interest, penalties, fines, attorneys’ fees, experts’ fees, court costs, remediation costs, and other expenses which result from the
use, storage, handling, treatment, transportation, release, threat of release or disposal of Hazardous Materials (as defined in the
Master Lease) in, on under or about the Sublease Premises, the Sublessor’s premises or the property as a whole, by Sublessee
or Sublessee’s agents, employees or contractors.

30.

PARKING

30.1. Sublessee and its employees shall have the right to eighty (80) unreserved monthly parking permits for the

parking of standard-sized automobiles in the Garage at no

19

additional charge. Subject to availability, Sublessee shall have the right to use additional unreserved monthly parking permits
for the parking of standard-sized automobiles in the Garage by providing at least thirty (30) days prior written notice to
Sublessor of its desire to use such additional permits. The charge for such additional permits shall be the prevailing rate
charged from time to time by Sublessor or the Garage operator (currently $165.00 per permit, per month).

30.2. Throughout the Sublease Term and, Sublessor shall provide access to the Garage through the Building for

Sublessee’s employees.

30.3. Sublessor may establish rules and regulations regarding Sublessee’s use of the Garage.

31.

BROKERAGE

Sublessee and Sublessor represent and warrant to each other that only Kelleher & Sadowsky Associates, Inc.

(“Broker”) had any part, or was instrumental in any way, in bringing about this Sublease. Sublessor agrees to pay any
brokerage fee due to Broker pursuant to a separate agreement with Broker. Each party agrees to indemnify, defend and hold
the other party harmless from and against any claims made by any other broker or other person alleging
that such broker, or person is owed a brokerage commission, finder’s fee or similar compensation, by reason of or in
connection with this Sublease and relating to communications with such indemnifying party, and any loss, liability, damage,
cost and expense (including, without limitation, reasonable attorneys’ fees) in connection with such claims. All fees owed to
Broker shall be satisfied by Sublessor.

32.

APPLICABLE LAW, HEADINGS, INTEGRATION AND
SIGNATURES

This Sublease shall be construed and enforced in accordance with the laws of The Commonwealth of Massachusetts.

Section and section headings are not a part hereof and shall not be used to interpret the meaning of this Sublease. This
Sublease forms the complete and entire understanding with respect hereto between the parties, and merges all prior and
contemporaneous negotiations and understandings. This Sublease may not be modified or amended except by a written
instrument. The parties hereto rely on no representations other than those set forth herein. If any provision of this Sublease or
portion of such provision or the application thereof to any person or circumstances is held invalid, the remainder of the
Sublease or of such provision and application thereof to other persons and circumstances shall not be affected thereby

This Sublease may be executed in counterparts, each of which shall be deemed an original, but all of which, taken

together, shall constitute one and the same instrument.
Signatures to this Sublease transmitted by telecopy or email shall be valid and effective to bind the party so signing. Each
party agrees to promptly deliver an execution original to this Sublease with its actual signature to the other party, but a failure
to do so shall not affect the enforceability of this Sublease, it being expressly agreed that each party to this Sublease shall be
bound by its own telecopied or emailed signature and shall accept the telecopied or emailed signature of the other party to this
Sublease.

20

[SIGNATURES ON FOLLOWING PAGE]

21

IN WITNESS WHEREOF, the said parties hereunto set their hands and seals this 14th day of June, 2022.

SUBLESSOR:

     SUBLESSEE:

THE PAUL REVERE LIFE INSURANCE COMPANY

MUSTANG BIO, INC.

By:  Devin Bloss (Jun 15, 2022 09:32 EDT)
Name: Devin Bloss
Its: AVP, Strategic Sourcing

By:  Manuel B Litchman (Jun 14, 2022 11:48 EDT)
Name: Manuel Litchman
Its: President and Chief Executive Officer

22

FLOOR PLAN(S) SHOWING SUBLEASE PREMISES ATTACHED TO AND MADE PART OF
THE SUBLEASE BETWEEN THE PAUL REVERE LIFE INSURANCE COMPANY AND MUSTANG BIO, INC.

EXHIBIT A

[See attached.]

A-1

2

REDACTED COPY OF MASTER LEASE ATTACHED TO AND MADE PART OF
THE SUBLEASE BETWEEN THE PAUL REVERE LIFE INSURANCE COMPANY AND MUSTANG BIO, INC.

EXHIBIT B

[Note: To be attached.]

B-1

EXHIBIT C

WORK LETTER 
ATTACHED TO AND MADE PART OF
THE SUBLEASE BETWEEN THE PAUL REVERE LIFE INSURANCE COMPANY 
AND MUSTANG BIO, INC.

Sublease: Defined Terms. The Sublease is hereby incorporated by reference to the extent that the provisions of this

1.
Work Letter apply thereto. Terms not otherwise defined in this Work Letter shall have the meanings given to them in the
Sublease.

Sublessee’s Work. Sublessee shall, at Sublessee’s sole cost and expense (subject to application of the Allowance as

2.
provided below) provide all labor, materials, and equipment necessary for Sublessee’s initial tenant improvements (the
“Sublessee’s Work”). The Sublessee’s Work constitutes an Alteration under the Master Lease and, in addition, Sublessee’s
Work shall be treated as constituting a portion of the Tenant’s Work and shall comply with the requirements of Section 1.9 of
Exhibit FF to the Master Lease and Article 5 of the Master Lease. Sublessee’s Work shall comply with Sublessor’s
sustainability practices and must be in conformance with the United States Green Building Council Leadership in Energy and
Environmental Design (“LEED”) 2009 criteria for Certified Silver status.

3.

Plans and
Specifications.

(a)

Promptly following the execution of the Sublease, Sublessee, shall cause to be prepared architectural drawings
and specifications for Sublessee’s Work (the “Preliminary Plans”). MEP/PP plans and specifications shall be performed on a
design/build basis by qualified subcontractors and submitted for approval with the Final Plans. The Preliminary Plans shall
provide for improvements that (i) satisfy all Requirements (including the Americans with Disabilities Act); (ii) are consistent
in quality to the improvements made by Sublessor in the Building; (iii) do not adversely affect the Building or any Building
system; and (iv) comply with the Tenant LEED Requirements as set forth in Exhibit E. The Preliminary Plans shall be
submitted to Sublessor as soon as available, but not later than thirty (30) days following the Commencement Date (the “Plan
Submission Date”) and shall be subject to Sublessor’s and Master Lessor’s written approval. The Preliminary Plans must
reflect all of the work to be performed as part of Sublessee’s Work. Sublessor shall use commercially reasonable efforts to
provide Sublessee with any comments or objections to the Preliminary Plans promptly. Sublessor shall either approve such
plans and specifications or provide Sublessee with the reasons that Sublessor or Master Lessor is withholding such approval. If
Sublessor or Master Lessor does not approve the Preliminary Plans when submitted, Sublessee shall promptly cause its
architect to revise the Preliminary Plans in a manner reasonably acceptable to Sublessor and Master Lessor and consistent with
such comments, and then resubmit to Sublessor and Master Lessor for approval.

(b)

Once Sublessor and Master Lessor have approved the Preliminary Plans, Sublessee shall promptly cause its

architect to prepare (and deliver to Sublessor and Master Lessor) complete, detailed working plans and specifications
(consistent with the Sublessor and Master Lessor approved Preliminary Plans) sufficient to obtain the necessary building
permits

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and to then build-out the Sublessee’s Work (the “Final Plans”). Such Final Plans must be submitted to Sublessor and Master
Lessor for approval by no later than fourteen (14) days after Sublessor’s and Master Lessor’s approval of the Preliminary
Plans. The Final Plans, once approved by Sublessor, will be the plans which Sublessee shall use to complete the Sublessee’s
Work.

4.

Construction.

(a)

Upon approval of the Final Plans, Sublessee shall select a general contractor to construct Sublessee’s Work.
Such selection shall be submitted for approval to Sublessor and Master Lessor in writing (along with information regarding
such general contractor’s experience and financial capability and the fees which such general contractor has agreed to charge
for the Sublessee’s Work) by no later than ten (10) days following Sublessor’s approval of the Final Plans. Once submitted to
Sublessor and Master Lessor, Sublessor shall approve or disapprove such selection (such approval not to unreasonably be
withheld) and use commercially reasonable efforts to obtain Master Lessor’s approval. If disapproved, Sublessor shall provide
the reasons for disapproval in writing to Sublessee whereupon Sublessee shall promptly submit an
alternative general contractor for approval, and such process will continue until the Sublessee’s contractor has been approved
by Master Lessor and Sublessor.

(b)

Sublessee’s contractor will not be permitted to start construction until: (i) Sublessee has obtained all permits

and approvals from applicable governmental authorities and
(ii) Sublessee’s contractor has submitted evidence of insurance to Sublessor and Master Lessor in accordance with the
requirements of Schedule 1 attached hereto. The Sublessee’s Work shall be completed by the selected contractor in a first class
and workmanlike manner in accordance with the Final Plans and in compliance with all applicable Requirements. During the
performance of the Sublessee’s Work, Sublessee will have weekly progress meetings with Sublessor and Master Lessor and
their construction representatives to review and inspect the progress of Sublessee’s Work. Sublessee shall use commercially
reasonable efforts to prosecute the Sublessee’s Work such that same is Substantially Completed (as defined below) on or
before the Anticipated Commencement Date. The Premises shall be deemed substantially completed (“Substantially
Completed” or “Substantially Complete”) when Sublessee is in receipt of a Certificate of Occupancy or Temporary Certificate
of Occupancy (punchlist items excepted) for the Sublease Premises. Sublessee further agrees to indemnify, defend, and save
and hold Sublessor harmless for claims for injuries to persons or damage to the property of others arising from Sublessee's
Work except to the extent caused by the gross negligence or willful misconduct of Sublessor, its agents, employees or
contractors. Sublessor, in Sublessor's reasonable discretion, may from time to time establish such reasonable rules and
regulations for protection of property and the general safety of occupants and invitees of the Building during the
construction of the Sublessee’s Work. Such rules and regulations shall apply to Sublessee and Sublessee's contractor as though
established upon the execution of the Sublease.

(c)

Changes in the Sublessee’s Work may be accomplished only by a Change Order (defined below) approved by

Master Lessor after Sublessor’s written request. As used in this Work Letter, a “Change Order” shall mean a written
instrument prepared by Sublessee and signed by Master Lessor, Sublessor and Sublessee stating their agreement upon all of
the following: (i) the change in the Sublessee’s Work; (ii) the extent of the adjustment in the cost of

C-2

such Sublessee’s Work; and (iii) the extent of the adjustment in the Anticipated Commencement Date, if any.

(d)

Approximately three (3) Business Days prior to the date when
Sublessee

anticipates the Sublessee’s Work will be Substantially Completed, Sublessor and Sublessee shall inspect the Sublease
Premises. Upon completion of the inspection, unless Sublessor shall notify Sublessee in writing regarding any observed
deficiencies in the Sublessee’s Work that go beyond punch list items, which notice shall be delivered to Sublessee, if at all,
within three (3) Business Days next following Sublessor’s inspection, it shall be presumed that the Sublessee’s Work is
Substantially Completed, except for punch list items. Within three (3) Business Days after the Sublessee’s Work is
Substantially Completed, Sublessor and Sublessee shall inspect the Sublease Premises, and Sublessor and Sublessee shall
agree on a punch list of minor finishing and adjustment which Sublessee has not completed materially in accordance with the
Final Plans or which needs to be repaired. Sublessee agrees to complete the items set forth on the punch list within sixty (60)
days of receipt of such list. Failure to include an item on the punch list will not diminish the responsibility of Sublessee to
complete such Sublessee’s Work in accordance with
the Final Plans. Sublessee shall provide to Sublessor, or cause Sublessee’s contractor to provide to Sublessor, copies of all as
built and shop plans, specifications, warranties, operating and
maintenance manuals, shop drawings and other documents provided by the Sublessee’s contractor concerning the Sublessee’s
Work within sixty (60) days after the punch-list for the Sublessee’s Work is submitted to Sublessor.

5.

Allowance and Supervision
Fee.

(a)

Sublessor shall pay to Sublessee an amount not to exceed Two Hundred Sixty- Five Thousand Thirty and

00/100 Dollars ($265,030.00) (the “Allowance”) toward the cost of Sublessee’s Work to the extent permitted by the terms of
this Section and provided that as of the date on which Sublessor is required to make such payment: (i) this Sublease is in full
force and effect, and (ii) no Event of Default then exists. Sublessee shall pay all costs of Sublessee’s Work in excess of the
Allowance. Sublessor shall pay the Allowance solely on account of plans, designs and specifications commissioned by
Sublessee with respect to the completion of the Sublessee Work and hard construction costs and labor directly related to the
Sublessee’s Work and materials, furniture and equipment approved by Sublessor and delivered to the Sublease Premises in
connection with the Sublessee’s Work. Any amount of the Allowance which has not been requisitioned by sixty (60) days
following the Commencement Date, shall be retained by Sublessor and Sublessee shall have no further right to claim thereto.

(b)

Sublessor shall make progress payments on account of the Allowance to Sublessee on a monthly basis, for the
Sublessee’s Work performed during the previous month, less a retainage (“Retainage”) equal to five percent (5%) of the total
contract price. Sublessor’s
progress payments shall be equal to 100% of the amounts owed by Sublessee under the contract less Retainage. Such progress
payments shall be made payable directly to Sublessee or contractor (at Sublessor’s election) within thirty (30) days following
the delivery to Sublessor of requisitions therefor. Each such requisition shall be executed by a duly authorized officer of
Sublessee, and shall be accompanied by (i) with the exception of the first requisition, copies of partial waivers of lien from all
contractors, subcontractors, and material suppliers covering all work and materials which were the subject of previous
progress payments by Sublessor, (ii) a

C-3

certification from Sublessee’s architect and contractor on completed AIA Forms G702 and G703, (iii) a requisition certificate
substantially in the form of the Requisition Certification attached hereto as Schedule 2 and incorporated herein by this
reference and (iv) such additional information as may be reasonably required by Sublessor in accordance with commercially
reasonable construction lending requirements. Sublessor shall hold such Retainage and disburse the Retainage, or portions
thereof as requisitioned by Sublessee from time to time on account of subcontractors who have completed their respective
portions of the job, upon submission by Sublessee to Sublessor of Sublessee’s requisition therefor accompanied by all
documentation required under the foregoing provisions of this Section, together with (A) proof of the satisfactory completion
of all required inspections and issuance of any required approvals, permits and sign offs for the work of such subcontractor, or
with respect to the work of the Sublessee’s general contractor, the Sublessee’s Work, by governmental authorities having
jurisdiction thereover (including issuance of the Certificate of Occupancy), and (B) issuance of final lien waivers by all
contractors, subcontractors and material suppliers covering all of the Sublessee’s Work or the portion thereof as applicable
(which final lien waivers may be conditioned upon, or delivered concurrent with, payment of such Retainage). In addition,
concurrent with the final requisition for the Retainage, Sublessee shall submit “as-built” plans and specifications for the
Sublessee’s Work. The right to receive the Allowance is for the exclusive benefit of Sublessee, and in no event shall such right
be assigned to or be enforceable by or for the benefit of any third party, including any contractor, subcontractor, materialman,
laborer, architect, engineer, attorney or other person or entity (excepting only a permitted assignee of Sublease).

(c)

Sublessee shall pay on demand to Sublessor a construction supervision fee in the amount of four percent (4%)

of the total cost of constructing Sublessee’s Work.

Sublessee Work Standards. Sublessee shall cause the Sublessee Work to be done in a good and workmanlike manner in

6.
conformity with all applicable Requirements and insurance underwriters. Sublessee shall secure and pay for all permits and
fees, licenses, and inspections necessary for the proper execution and completion of the Sublessee Work. Sublessee shall
comply with and give all notices required by all applicable federal, state and local laws, ordinances and building codes, and
requirements of public authorities and insurance underwriters. Sublessee shall be responsible for initiating, maintaining, and
supervising all safety precautions and programs in connection with performance of the Sublessee Work. Sublessee shall
procure insurance of the types and coverage amounts required pursuant to the Sublease or as otherwise may be appropriate
given the nature and extent of Sublessee Work. Sublessee shall be responsible for the removal of all debris within and adjacent
to the Sublease Premises created by Sublessee Work. All Sublessee Work shall be performed in a manner and by contractors
who shall not interfere with the use of the Building by other tenants or disturb harmonious labor relations with Sublessor’s
employees, agents, contractors or subcontractors. In the event that Sublessee, its employees, agents, contractors or
subcontractors conflict with or interfere with labor employed by Sublessor, its contractors or subcontractors, or in the event
that any work stoppages, jurisdictional labor dispute or other interference with Sublessor, or Sublessor’s employees, agents,
contractors or subcontractors occurs, of which Sublessor shall be the sole and absolute judge, Sublessor shall have the right to
require Sublessee, upon written demand, to remove or cause the removal forthwith of all Sublessee’s contractors and

C-4

subcontractors from the Premises, and Sublessee agrees to comply with such demand immediately.

C-5

Schedule 1

Contractor Insurance Requirements

The following must be named as additional insureds:

THE PAUL REVERE LIFE INSURANCE COMPANY ONEMERC LLC

Each contractor and subcontractor must provide coverage in an amount equal to or greater than those provided below:

Comprehensive General Liability:

$1,000,000 Each Occurrence
$2,000,000 General Aggregate

Automobile Liability Policy

$1,000,000 Owned, Non-owned & Hired Vehicles:
Bodily Injury and Property Damage 
Combined Single Limit

Umbrella Liability

$5,000,000

Worker’s Compensation:
Coverage A (Worker’s Compensation)

$500,000.00 Coverage B (Employer’s Liability)

$500,000.00

In addition to the above, Sublessor requires notification, in writing, TEN (10) days prior to policy cancellation for any reason.

C-6

Schedule 2

Form of Requisition Certification

In connection with that certain Sublease dated 

, 2022 (the “Sublease”), by and between The Paul

Revere Life Insurance Company (the “Sublessor”), and Mustang Bio, Inc. (the “Sublessee”) with respect to the improvement
of the Sublease Premises located within the Building at One Mercantile Place in Worcester, Massachusetts (the “Project”)
(capitalized terms appearing but not defined herein shall have the meanings ascribed to such terms in the Sublease), Sublessee
​ ​
hereby certifies as follows with respect to Draw Request #

:

a.

To the knowledge of the undersigned, at the date hereof no suit or proceeding at law or in equity, and no

notice has been received that any investigation or proceeding of any governmental body has been instituted or is threatened
against Sublessee for matters directly relating to the Sublease Premises except for the following: none.

b.

The labor, materials, equipment, work, services and  supplies  described  herein  have  been  performed  upon  or

furnished to the Sublease Premises in full accordance with the Final Plans for Sublessee’s Work.

c.

All bills for labor, materials, equipment, work, services and supplies furnished in connection with the Project,

which could give rise to a mechanic’s lien if unpaid, have been paid, will be paid out of the requested advance or are not yet
due and payable.

d.

All claims for mechanic’s liens to the extent of sums billed and paid for labor, materials, equipment, work,

services or supplies furnished in connection with the Project through the last day of the period covered by the requested
advance have been effectively waived in writing, or will be effectively waived in writing when payment is made, and such
written waivers from the contractor shall be delivered prior to the next advance or final advance for the Project.

e.

All funds advanced under the Allowance to date have been utilized as specified in the Draw Requests pursuant

to which the same were advanced, exclusively to pay costs incurred for or in connection with the Sublessee’s Work at the
Project, and no portion of the Allowance that has been paid to Sublessee has been paid for labor, materials, equipment, work,
services or supplies incorporated into or employed in connection with any project other than the Project. The undersigned
further represents that all funds covered by this Draw Request are for payment for labor, materials, equipment, work, services
or supplies furnished solely in connection with the Project.

The advances and disbursements on the attached sheets are hereby approved and authorized.

Date: 

MUSTANG BIO, INC.

By: Its:

C-7

 
 
   
 
 
EXHIBIT D

RULES AND REGULATIONS 
ATTACHED TO AND MADE PART OF
THE SUBLEASE BETWEEN THE PAUL REVERE LIFE INSURANCE COMPANY 
AND MUSTANG BIO, INC.

1. Tenant shall not make any room-to-room canvas to solicit business from other tenants in the Building and shall not
exhibit, sell or offer to sell, use, rent or exchange any item or services in or from the Leased Premises unless ordinarily
included within Tenant’s use of the Leased Premises.

2. Tenant shall not make any use of the Leased Premises which may be dangerous to person or property or which shall

increase the cost of insurance or require additional insurance coverage.

3. Tenant shall not paint, display, inscribe or affix any sign, picture, advertisement, notice, lettering or direction or install
any lights on any part of the outside or inside of the Building, other than the Leased Premises, and then not on any
part of the inside of the Leased Premises which can be seen from outside the Leased Premises, except as approved by
Landlord in writing.

4. Tenant shall not use the name of the Building in advertising or other publicity, except as the address of its business,

and shall not use pictures of the Building in advertising or publicity.

5. Tenant shall not obstruct or place objects on or in sidewalks, entrances, passages, courts, corridors, vestibules, halls,
elevators and stairways in and about the Building. Tenant shall not place objects against glass partitions or doors or
windows or adjacent to any open common space which would be unsightly from the Building corridors or from the
exterior of the Building.

6. Bicycles  shall  not  be  permitted 

in 

the

Building.

7. Tenant shall not allow any animals, other than Seeing Eye dogs and service animals, in the Leased Premises or the

Building.

8. Tenant shall not disturb other tenants or make excessive noises, cause disturbances, create excessive vibrations, odors
or noxious fumes or use or operate any devices that play loud or offensive music or emit excessive sound waves or are
dangerous to other tenants of the Building or that would interfere with the operation of any device or equipment or
radio or television broadcasting or reception from or within the Building or elsewhere, and shall not place or install
any projections, antennae, aerials or similar devices outside of the Building or the Leased Premises.

9. Tenant  shall  not  waste  electricity  or  water  and  shall  cooperate  fully  with  Landlord  to  assure  the  most  effective
operation  of  the  Building’s  heating  and  air  conditioning  systems,  and  shall  refrain  from  attempting  to  adjust  any
controls  except  for  the  thermostats  within  the  Leased  Premises.  Tenant  shall  keep  all  doors  to  the  Leased  Premises
closed when not in use.

10. Landlord shall furnish an access card for the main entrance and Common Areas to the Building for each of Tenant’s
employees at the then-current rate charged by Landlord. Tenant and Tenant’s employees shall not give their building
access cards to any other individual. Tenant and Tenant’s employees shall not piggyback or allow other individuals to
piggyback through access-controlled building entrances. When a Tenant’s employee

D-1

ceases to work at the Leased Premises, Tenant shall require such employee to return the access card, and Tenant shall
notify  Landlord  of  such  in  order  to  allow  Landlord  to  deactivate  such  access  card.  When  the  Lease  is  terminated,
Tenant shall deliver all access cards to Landlord, will deactivate the access key or other security system for the doors to
the Leased Premises, and will provide to Landlord the means of opening any safes, cabinets or vaults left in the Leased
Premises.

11. Tenant shall not install any signal, communication, alarm or other utility or service system or equipment without the

prior written consent of Landlord.

12. Tenant  shall  not  use  any  draperies  or  other  window  coverings  instead  of  or  in  addition  to  the  Building  standard

window coverings designated and approved by Landlord for exclusive use throughout each Building.

13. Landlord  may  require  that  all  persons  who  enter  or  leave  the  Building  identify  themselves  to  building
management/Landlord  personnel  by  registration  or  otherwise.  Landlord,  however,  shall  have  no  responsibility  or
liability for any theft, robbery or other crime in the Building. Tenant shall assume full responsibility for protecting the
Leased Premises, including keeping all doors to the Leased Premises locked after the close of business. Tenant shall
comply with any and all written security procedures promulgated by Landlord from time to time.

14. Tenant shall not overload floors; and Tenant shall obtain Landlord’s prior written approval, which approval shall not
be  unreasonably  withheld,  conditioned  or  delayed  (provided  that  Tenant  shall  be  responsible  for  the  cost  of  any
changes  to  the  Building  or  Leased  Premises  required  because  of  the  installation  of  any  such  objects),  as  to  size,
maximum  weight,  routing  and  location  of  business  machines,  safes,  and  heavy  objects.  Tenant  shall  not  install  or
operate machinery or any mechanical devices of a nature not directly related to Tenant’s ordinary use of the Leased
Premises.

15. In  no  event  shall  Tenant  bring  into  the  Building  flammables  such  as  gasoline,  kerosene,  naphtha  and  benzene,  or

explosives or firearms or any other articles of an intrinsically dangerous nature.

16. Furniture,  equipment  and  other  large  articles  may  be  brought  into  the  Building  only  at  the  time  and  in  the  manner
designated  by  Landlord. At  no  time,  furniture  equipment  and  other  large  articles  shall  not  be  brought  through  the
revolving doors at the building entrances. Tenant shall furnish Landlord with a list of furniture, equipment and other
large articles which are to be removed from the Building. Movements of Tenant’s property into or out of the Building
and within the Building are entirely at the risk and responsibility of Tenant. Tenant shall be responsible for damage to
the Building arising from such movement activity.

17. No person or contractor, unless approved in advance by Landlord, shall be employed to do janitorial work, interior

window washing, cleaning, decorating or similar services in the Leased Premises.

18. Tenant shall not use the Leased Premises for lodging, cooking (except for microwave reheating and coffee makers) or

manufacturing or selling any alcoholic beverages or for any illegal purposes.

19. Tenant  shall  cooperate  and  participate  in  all  security  health,  safety  and  well-being  programs  affecting  the

Building.

20. Tenant shall not loiter, eat, drink, sit or lie in the lobby or other public areas in the Building. Tenant shall not go onto

the roof of the Building or any other non-public areas

D-2

of  the  Building  (except  the  Leased  Premises),  and  Landlord  reserves  all  rights  to  control  the  public  and  non-public
areas of the Building. In no event shall Tenant have access to any electrical, telephone, plumbing or other mechanical
closets without Landlord’s prior written consent.

21. Tenant  shall  not  use  the  freight  or  passenger  elevators,  loading  docks  or  receiving  areas  of  the  Building  except  in

accordance with regulations for their use established by Landlord.

22. Tenant shall not dispose of any foreign substances in the toilets, urinals, sinks or other washroom facilities, nor shall
Tenant permit such items to be used other than for their intended purposes; and Tenant shall be liable for all damage
as a result of a violation of this rule.

23. Tenant  acknowledges  that  the  Real  Property  is  a  non-smoking

campus.

24. Tenant and Tenant’s employees may park in the spaces identified as Tenant parking. Tenant’s guests and invitees may
park in the spaces identified as “Visitor Parking”. Landlord shall have no liability for theft or damage of/from/to any
Vehicles parked on the Real Property. Tenant’s employees shall not park in spaces identified as “Visitor Parking”.

25. Consumption  of  alcohol  is  strictly  forbidden  in  all  Common  Areas  and  the  parking

garage.

26. Tenant  and  Tenant’s  employees  shall  not  wear  any  clothing  that  contains  offensive  language  or  is  considered
inappropriate at all times while in Common Areas. Examples of inappropriate clothing includes, but not limited to,
clothing  that  is  too  tight,  short  or  revealing,  clothing  that  is  frayed  or  torn,  clothing  that  is  not  cleaned,  t-shirts  or
clothing that contains logos or slogans that would be deemed offensive to other building occupants or tenants.

27. Tenant and Tenant’s employees shall follow all posted speed limits in parking lots, access roads and parking garages.
Tenant  and  Tenant’s  employees  shall  obey  all  directional  signage  posted  in  parking  lots,  access  roads  and  parking
garages.

28. Tenant and Tenant’s employees shall not bring any illegal or illicit drugs, or drug paraphernalia onto the Landlord’s

property.

D-3

EXHIBIT E

OPERATION AND MAINTENANCE GUIDELINES 
ATTACHED TO AND MADE PART OF
THE SUBLEASE BETWEEN THE PAUL REVERE LIFE INSURANCE COMPANY 
AND MUSTANG BIO, INC.

OPERATION AND MAINTENANCE GUIDELINES

1.
Sublessee shall comply with all applicable provisions of (i) the LEED CS Matrix for Base Building attached as Exhibit
P-1 to the Master Lease and (ii) the LEED CI Matrix for Tenant’s Work attached as Exhibit P-2 to the Master Lease (copies of
which are attached hereto), as the same may be amended from time to time.

Sublessee shall comply with the following “Tenant LEED Requirements”, as the same may be amended from time to

2.
time:

Minimum Program Requirement:
Tenants shall share any energy and water usage data which it may have for a period of at least five years.

EAp3: Fundamental Refrigerant Management
All Tenant installed mechanical cooling equipment will comply with the requirements of EAp3. There will be zero use
of CFC-based refrigerants in all tenant-installed new mechanical cooling equipment.

IEQp1: Minimum IAQ Performance
All HVAC systems designed and installed by the Tenant shall meet the minimum requirements of sections 4 through 7
of ASHRAE Standard 62.1-2007. In the event any base building system provided by the Landlord that needs
modification to meet the minimum requirements of sections 4 through 7 of ASHRAE 62.1-2007 shall be the
responsibility of the Tenant. Tenant shall provide ventilation calculations for all base building systems serving Tenant
areas as well as Tenant systems serving Tenant areas. Tenant shall utilize the “62MZCalc” spreadsheet for calculations
provided to the Landlord for review and acceptance.

IEQc1: Outdoor Air Delivery Monitoring
Tenant shall provide CO2 monitoring control within all densely occupied spaces. Densely occupied space would apply
to space with a density equal to or greater than 25 people per 1000 square feet. Tenant shall install CO2 monitors
between 3 and 6 feet above finished floor. In the event a Tenant installs additional air handling systems such system
shall be provided with a direct outdoor air monitoring device measuring the minimum outdoor air intake flow with an
accuracy of +/- 15 percent of the design outdoor air rate minimum as defined by ASHRAE 62.1-2007 (with errata but
without addenda) for each mechanical ventilation system where 20 percent or more of the design supply airflow serves
non densely occupied spaces. All tenant installed CO2 control

F-1

systems shall be of permanent type to ensure that all minimum ventilation requirements are maintained. Monitoring
equipment shall alarm to a building operator through the building automation control system in the event airflow values
or CO2 levels vary by 10 percent or more from the designed value.

IEQc5: Indoor Chemical & Pollutant Source Control
Employ permanent entryway systems at least 10 feet long in the primary direction of travel to capture dirt and
particulates entering the building at regularly used exterior entrances. Acceptable entryway systems include
permanently installed grates, grills and slotted systems that allow for cleaning underneath. Roll-out mats are acceptable
only when maintained on a weekly basis by a contracted service organization.

IDc1.1: Innovation in Design: Fundamental & enhanced commissioning required for all tenant spaces
Implement fundamental and enhanced commissioning process activities in accordance with the requirements listed
under EA Prerequisite 1 and EA Credit 3 in the LEED Reference Guide for Green Building Design and Construction,
2009 Edition.

IDc1.4: Innovation in Design: Green Housekeeping
Tenants will implement a Green Cleaning Policy that complies with LEED 2009 for Existing Buildings: Operations
and Maintenance, IEQ pre-requisite 3.

IDc1.5: Innovation in Design: IAQ Plan for 100% of Tenants
Develop and implement a construction indoor air quality management plan for the construction and preoccupancy
phase of the tenant space as follows and as per IEQ Credit 3:
During construction, meet or exceed the recommended control measures of the Sheet Metal and Air
·
Conditioning National Contractors Associations (SMACNA) IAQ Guidelines for Occupied Buildings under
Construction, 2nd Edition 2007, ANSI/SMACNA 008-2008 (Chapter 3).
·
handlers are used during construction, filtration media with a minimum efficiency reporting value (MERV) of 8 must
be used at each return air grille, as determined by ASHRAE Standard 52.2-1999 (with errata but without addenda).
Replace all filtration media immediately prior to occupancy.

Protect stored on-site and installed absorptive materials from moisture damage. If permanently installed air

Sublessee shall comply with the following “Green Cleaning Requirements”, as the same may be amended from time to

3.
time:

Green Cleaning Program Overview

To demonstrate its commitment to sustainable greening of the Building, Sublessor has made efforts to
implement a green cleaning program. Sublessee shall perform green cleaning of the Sublease Premises. The program
listed in the remainder of this section is a fully comprehensive green cleaning program that is consistent with USGBC’s
LEED rating system.

E-2

Purpose of Green Cleaning

Many janitorial cleaning products have been shown to degrade indoor air quality, pollute the water and
negatively impact the health of sensitive occupants. In an effort to maintain a clean Building, janitors often use harsh
solutions that, while disinfecting the Building, contaminate the indoor air. It is Sublessor’s desire to maintain both a
clean Building and a healthy environment for its occupants and Sublessor is therefore committed to the Green Cleaning
Practices in this policy.

Sublessee Participation

The  following  elements  will  be  incorporated  into  the  cleaning  process:  green  product  specification,  staff
training, solution storage, dilution and safe handling and equipment specifications. Sublessee agrees to comply with the
cleaning program.

Low Environmental Impact Cleaning Policy:

Hand Hygiene

Sublessee shall promote healthy hand hygiene by providing soap and soap dispensers in restrooms, break rooms

and other areas in the Sublease Premises.

Chemical Storage Guidelines
Sublessee  must  comply  with  Sublessor’s  program  to  reduce  the  exposure  of  the  Building  occupants  to  potentially
dangerous  chemical,  biological  and  particle  contaminants  which  adversely  impact  air  quality,  health  and  the
environment.

1. Any chemical stored in Sublease Premises must be in a locked container which encloses the liquid cleaning

products and delivers out proper specified measurement for dilution.

2. The solutions used by Sublessee must be stored in a janitor’s closet(s), and the janitorial staff must follow

these guidelines:

a. Material Safety Data Sheets (MSDS) for all chemicals and cleaning products must be available to
all employees and stored on site with the chemicals (Sublessee Personnel are trained on MSDS and
chemical handling annually);

b. All  containers  must  be  properly 

labeled 

to  be  easily

identifiable;

c. All cleaning products must be properly and safely stored, and no liquids will be placed on shelves

above eye level;

d. Sublessee Personnel must use appropriate personal protective equipment when required

(e.g. gloves, proper footwear, etc.);

e. Chemical dilution systems must be adhered to;

and

E-3

f. Unnecessary  amounts  of  chemicals  should  not  be  stored  in  the  janitor’s

closet(s).

Special Treatment of Carpets

Carpet can be a source of biopollutants, dust and volatile organic compounds (VOCs). Pesticides and cleaning
products (such as stain removers) that remain on the carpet after initial application can volatilize (rise up into the air)
over time and contaminate the indoor air. The following carpet treatment guidelines will mitigate the need for carpet
cleaning solutions through both preventive and prescriptive treatment:

1. Prevent
stains.

a. Clean  up  spills  promptly  using  cold  water  and  one  or  more  blotting

cloths
b. Make  a 
occupants

spill  kit  available 

to

2. Promptly  clean  and  thoroughly  dry  carpets  if  they  should  become  saturated  with  water;  quick  action
following a leak or other water damage may prevent carpet loss and the growth of mold and/or mildew.
(Do not attempt to clean a moldy carpet without proper protective equipment, clothing, respirators and air
filters. Special training may be required to adequately deal with a water- soaked carpet.)

Reducing Microbial Growth through Proper Cleaning

The following are basic guidelines to minimize the need for antimicrobial products at the Building:

1. Clean 

first 

and 

then 

apply

disinfectant

a. Most  disinfectants  are  not  cleaners  and  are  usually  only  effective  on  a  clean

surface

b. Wait the recommended time before rinsing the antimicrobial solution from the surface (usually at

least 10 minutes)

2. Use disinfectants only when and where required; ordinary detergents should remove more microbes than

disinfectants

3. Change  mop  heads  and  sponges  daily  and  properly

dispose

4. Change cleaning water frequently (water used in mop buckets, etc.); do not waste water by overfilling mop

5.

buckets, etc.
Intentionally clean areas where water collects and condenses; areas such as refrigerator and air conditioner
pans as well as air cleaner/humidifier machines

E-4

6. Use  a  drain  maintainer  (containing  enzymes)  if  drains  clog  or  have  an

odor

Janitorial Training Requirements

Sublessee  will  provide  training  of  Sublessee  Personnel  in  the  hazards,  use,  maintenance  and  disposal  of  cleaning
chemicals, dispensing equipment and packaging. Documentation of the training sessions, attendees and topics covered
shall be submitted to Sublessor upon request by Sublessor.

1. Basic 

Janitorial

Training
a.

Janitorial  workers  should  receive  basic  training,  including  the  Green  Cleaning  specifications
delineated in Sublessor’s Green Cleaning Policy

b. An  average  of  8  hours  of  training  per  custodian  per  year  is

required

2. Training

Specifications

a. Material safety data sheets

(MSDS)

b. Compliance with the Green Seal standard of GS –

37

c. Use and wear of Personal Protective

Equipment

d. Custodians should be informed of Sublessor’s product reporting requirements; all cleaning products

which are not on the GS-37 list must be approved by Sublessor Personnel
3. Provide  Sublessor  with  monthly  training  logs  indicating  the  attendees  and  the  training

topic

Green Cleaning Materials Policy
Sublessee  will  implement  a  sustainable  program  for  the  purchase  of  cleaning  materials  and  products  that  reduce  the
environmental impact of its janitorial activities.

To the extent practical, no cleaning or disinfecting products should contain ingredients that are carcinogens,
mutagens or teratogens. These include chemicals listed by the U.S. EPA or the National Institute for Occupational
Safety and Health on the Toxics Release Inventory (40 CFR, Section 372, Subpart D). If such products containing
these toxic chemicals must be used (cleaning solutions for specific equipment, etc.), only the minimum amounts should
be used, and the product must be disposed of properly. A complete list of toxic chemicals is maintained by the U.S.
EPA and can be found at the Toxic Release Inventory at www.epa.gov/tri/chemical. It is recommended that the
cleaning products used by Sublessee at the Building must meet the Green Seal standard of GS-37. The Green Seal
Organization offers extensive information regarding the GS- 37 standard on their website
www.greenseal.org/certification/environmental.cfm. A complete listing of Green Seal certified products is maintained
by the Green Seal organization and can be found at www.greenseal.org/findaproduct/index.cfm.

Low Environmental Impact Cleaning Equipment Policy

E-5

Sublessee  must  implement  an  equipment  program  to  reduce  building  contaminants  with  minimum  environmental
impact. Sublessee should purchase cleaning equipment that meets the following requirements:

· Vacuum cleaners meet the requirements of the Carpet & Rug Institute “Green Label” Testing Program –
Vacuum Cleaner Criteria and are capable of capturing 96% of particulates 0.3 microns in size and operates
with a sound level less than 70dBA.

·

· Hot water extraction equipment for deep cleaning carpets is capable of removing sufficient moisture such
that  the  carpets  can  dry  in  less  than  twenty-  four  (24)  hours  (not  applicable  –  restorative  carpet  care  is
provided by Sublessee).
Powered  maintenance  equipment  including  floor  buffers,  floor  burnishers  and  automatic  scrubbers  are
equipped with vacuums, guards and/or other devices for capturing fine particulates and shall operate with a
sound level less than 70dBA. Provide cut sheets on the vacuum equipment used on the Building to confirm
compliance with this requirement.
Propane-powered  floor  equipment  has  high-efficiency, 
engines.

low-emission

·

· Automated  scrubbing  machines  are  equipped  with  variable-speed  feed  pumps  to  optimize  the  use  of

cleaning fluids.

· Battery-powered  equipment  is  equipped  with  environmentally  preferable  gel

batteries.

· Where  appropriate,  active  micro  fiber  technology  is  used  to  reduce  cleaning  chemical  consumption  and

·

·

prolong life of disposable scrubbing pads.
Powered  equipment  is  ergonomically  designed  to  minimize  vibration,  noise  and  user
fatigue.
Equipment  has  rubber  bumpers  to  reduce  potential  damage  to  building
surfaces.

· A  log  will  be  kept  on-site  for all  powered  housekeeping  equipment  to  document  the  date  of  equipment
purchase  and  all  repair  and  maintenance  activities  and  include  subcontractor  cut  sheets  for  each  type  of
equipment  in  use  in  the  logbook. All  equipment  shall  be  in  new  condition  and  meet  the  green  cleaning
requirements.

· No  equipment  may  be  brought  on  site  unless  it  has  been  approved  by

Sublessor

Reporting
Sublessee  must  provide  documentation  of  its  comprehensive  green  cleaning  program  and  must  also  provide  written
updates, including a monthly record of supply purchases (indicating compliance with the GS-37 Standard), equipment
purchases and training on at least a quarterly basis.

Sublessee  should  keep  an  ongoing  log  book  that  documents  Sublessee’s  compliance  with  all  green  cleaning
requirements (supplies purchased, current equipment, MSDS sheets, equipment repairs, equipment taken out of service,
new equipment brought on site during

E-6

the  term  of  the  Sublease,  training  topics/dates/sign-off  sheets,  entryway  cleaning  log  and  any  other  green  cleaning
requirements stated in this Sublease).

Applying Green Cleaning to the Specifications
The  Low  Environmental  Impact  Cleaning  requirements,  the  Green  Cleaning  Materials  requirements  and  the  Low
Environmental  Impact  Cleaning  Equipment  requirements  are  to  be  applied  by  Sublessee  in  addition  to  any  Standard
(Base) Cleaning Specification required by Sublessor.

For example, the task “clean door glass and other adjacent glass areas” must be performed using a chemical that meets
the  Green  Seal  GS-37  Standard  and  microfiber  technology  in  lieu  of  paper  products  when  possible.  The  task  “fully
vacuum  all  carpeted  areas  from  wall  to  wall  including  walk-off  mats  and  edges”  must  be  performed  with  a  vacuum
cleaner that captures 96% of particulates 0.3 microns in size and operates with a sound level less than 70dBA.

Quality Control Measures
Sublessor is committed to maintaining the Building in an environmentally preferable way that will benefit the health of
the occupants, visitors, maintenance personnel and the natural environment. To this end, Sublessor routinely evaluates
the successes and shortcomings of all employed practices and makes immediate alterations accordingly. Building and
site  walk-throughs  are  completed  routinely  by  Sublessor  Personnel  to  ensure  adoption  and  proper  application.  A
cleaning audit is conducted routinely to assess the quality of the custodial services. Occupants are highly encouraged to
report any outstanding custodial issues to the Sublessee. New technologies for environmentally sensitive cleaning will
be  continuously  monitored  and  assessed  as  they  become  available  and  adopted  when  they  are  applicable.  Similarly,
this policy will be updated as needed to ensure that current and successful procedures are being carried out. As such,
this  policy  is  applicable  as  of  the  Effective  Date  of  the  Sublease  until  an  updated  version  is  drafted  when  deemed
necessary.

E-7

E-8

E-9

F-1

E-2

E-3

E-4

E-5

E-6

E-7

5534031.1
5534031.2
5534031.4

F-1

FIRST AMENDMENT TO SUBLEASE

Exhibit 10.23

THIS FIRST AMENDMENT TO SUBLEASE (this “Amendment”) is entered into as of the 25thday of October  , 2022
(the “Effective Date”), by and between THE PAUL REVERE LIFE INSURANCE COMPANY, a Massachusetts
corporation (the “Sublessor”), having a notice address of c/o Unum Group, 1 Fountain Square, Suite 120, Chattanooga,
Tennessee 37402, Attn: Corporate Real Estate Department, and MUSTANG BIO, Inc., a Delaware corporation (the
“Sublessee”), having a notice address of 377 Plantation Street, Worcester, Massachusetts 01605.

Recitals

A.

B.

C.

D.

E.

Sublessor is the tenant under that certain Lease dated June 17, 2010, by and between CitySquare II Development Co.
LLC (“CitySquare II”), as landlord, and Sublessor, as
tenant, as affected by that certain (i) Assignment and Assumption of Lease dated October 4, 2010, by and between
CitySquare II and One Mercantile Place LLC (“One Mercantile”), (ii) Letter Agreement dated November 11, 2011, by
and between One Mercantile and Sublessor, (iii) Second Amendment to Lease dated as of July 5, 2012, by and between
One Mercantile and Sublessor, (iv) Third Amendment to Lease dated as of December 19, 2012, by and between One
Mercantile and Sublessor, (v) Assignment and Assumption of Lease and Guaranty dated December 21, 2012, by and
between One Mercantile and ONEMERC, LLC (the “Master Lessor”), (vi) Letter Agreement dated May 2, 2013, by
and between Master Lessor and Sublessor, and (vii) Fourth Amendment to Lease dated as of September 16, 2015, by
and between Master Lessor and Sublessor (collectively, the “Master Lease”);

Pursuant to the Master Lease, Sublessor leases approximately 198,560 rentable square feet of space in the building
known as One Mercantile Place located at One Mercantile Street in Worcester, Massachusetts (the "Building")
together with approximately 851 parking spaces in the adjoining garage known as the Foster Street Garage
(collectively, the “Master Premises”);

Pursuant to the Sublease dated as of June 14, 2022, with a Commencement Date of July 1, 2022, by and between
Sublessor, as sublessor, and Sublessee, as sublessee (the "Sublease"), Sublessor has subleased to Sublessee
approximately 26,503 rentable square feet of space of the Master Premises located on the fourth (4th) floor of the
Building as more particularly described in the Sublease (the "Sublease Premises");

Sublessor is the current holder of the tenant's interest under the Master Lease and the sublessor's interest under the
Sublease, and Sublessee is the current holder of the sublessee's interest under the Sublease; and

Sublessor and Sublessee desire to amend the Sublease in order to extend the time to use the Allowance toward the cost
of Sublessee’s Work as described in Section 5 (a) of Exhibit C, the Work Letter.

NOW, THEREFORE, for valuable consideration, the receipt and sufficiency of which is hereby mutually

acknowledged, Sublessor and Sublessee hereby agree as follows:

1.

2.

3.

4.

5.

6.

Agreements

Capitalized Terms. Each capitalized term appearing but not defined herein shall have the meaning, if any,
ascribed to such term in the Sublease.

Recitals. The recitals above set forth are true and complete and are incorporated herein by
reference.

Extension of Time to Use Allowance. The last sentence of Section 5 (a) of Exhibit C to the Sublease is hereby
amended by replacing “Any amount of Allowance which has not been requisitioned by sixty (60) days
following the Commencement Date, shall be retained by Sublessor and Sublessee shall have no further right to
claim thereto” with “Any amount of Allowance which has not been requisitioned by July 31, 2023, shall be
retained by Sublessor and Sublessee shall have no further right to claim thereto.”

Effective Date. The parties agree that this First Amendment shall be effective from and after the Effective
Date and not during any period of time prior thereto. To the extent this First Amendment contains language
which purports to amend the Sublease with respect to periods of time prior to the Effective Date, such
language is for clarification purposes only and shall not be deemed to change the obligations of the parties
with respect thereto. In no event shall this First Amendment be construed to impose any liability on Sublessor
for any period of time preceding its leasing of the Master Premises from Master Lessor.

Ratification of Sublease Provisions. Except as otherwise expressly amended, modified and provided for in this
Amendment, Sublessee hereby ratifies all of the provisions, covenants and conditions of the Sublease, and
such provisions, covenants and conditions shall be deemed to be incorporated herein and made a part hereof
and shall continue in full force and effect.

Brokerage. Sublessor and Sublessee each represents to the other party that it has not authorized, retained or
employed, or acted by implication to authorize, retain or employ, any real estate broker or salesmen to act for it
or on its behalf in connection with this Amendment so as to cause the other party to be responsible for the
payment of a brokerage commission. Sublessor and Sublessee each agrees to indemnify, defend and hold the
other (and such other party’s employees and representatives) harmless from and against any claims, damages,
costs, expenses, attorneys’ fees or liability for compensation or charges which may be claimed by any such
unnamed broker, finder or similar party whom the indemnified party authorized, retained or employed, or
acted by implication to authorize, retain or employ, to act for the indemnifying party in connection with this
Amendment.

7.

Entire Amendment. This Amendment contains all of the agreements of the parties with respect to the subject
matter hereof and supersedes all prior dealings between the parties with respect to such subject matter.

First Amendment to Sublease

2

8.

9.

10.

11.

12.

13.

Authority. Sublessor and Sublessee each warrant to the other that the person or persons executing this
Amendment on its behalf has or have authority to do so and that such execution has fully obligated and bound
such party to all of the terms and provisions of this Amendment.

Binding Amendment. This Amendment shall be binding upon, and shall inure to the benefit of the parties
hereto, and their respective successors and assigns.

Governing Law. This Amendment shall be governed by the laws of The Commonwealth of
Massachusetts.

Severability. If any clause or provision of this Amendment is or should ever be held to be illegal, invalid or
unenforceable under any present or future law applicable to the terms hereof, then and in that event, it is the
intention of the parties hereto that the remainder of this Amendment shall not be affected thereby, and that in
lieu of each such clause or provision of this Amendment that is illegal, invalid or unenforceable, such clause or
provision shall be judicially construed and interpreted to be as similar in substance and content to such illegal,
invalid or unenforceable clause or provision, as the context thereof would reasonably suggest, so as to
thereafter be legal, valid and enforceable.

No Reservation. Submission of this Amendment for examination or signature is without prejudice and does not
constitute a reservation, option or offer, and this Amendment shall not be effective until execution and delivery
by all parties.

Counterparts. This Amendment may be executed simultaneously in two or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute one and the same instrument.
Additionally, telecopied of pdf signatures may be used in place of original signatures on this Amendment.
Sublessor and Sublessee intend to be bound by the signatures on the telecopied or pdf document, are aware
that the other party will rely on the telecopied or pdf signatures, and hereby waive any defenses to the
enforcement of the terms of this Amendment based on the form of signature.

[SIGNATURES ON FOLLOWING PAGE]

First Amendment to Sublease

3

IN WITNESS WHEREOF, the said parties hereunto set their hands and seals as of the Effective Date.

SUBLESSOR:

     SUBLESSEE:

THE PAUL REVERE LIFE INSURANCE COMPANY

MUSTANG BIO, INC.

By:  Devin Bloss (Oct 25, 2022 08:25 EDT)
Name: Devin Bloss
Its: AVP, Strategic Sourcing

First Amendment to Sublease

By:  

Name: Knut Niss
Its:       CTO

4

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the registration statements ( Nos. 333-255476 and 333-249657) on Form  S-3 and in the
registration statements (Nos. 333-266176, 333-258310, 333-258311, 333-225007, and 333-221819) on Form S-8 of our report dated
 March 29, 2023, with respect to the financial statements of Mustang Bio, Inc.

/s/ KPMG LLP
Hartford, Connecticut 
March 29, 2023

 
CERTIFICATION PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

EXHIBIT 31.1

I, Manuel Litchman, M.D., President and Chief Executive Officer (Principal Executive Officer), certify that:

(1)

I have reviewed this Annual Report on Form 10-K for the year ended December 31, 2022 of Mustang Bio, Inc. (the registrant);

(2) Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered
by this report;

(3) Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects,

the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

(4) The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined
in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and
15d-15(f)) for the registrant and have:

(a) designed  such  disclosure  controls  and  procedures,  or  caused  such  disclosure  controls  and  procedures  to  be  designed  under  our
supervision,  to  ensure  that  material  information  relating  to  the  registrant  is  made  known  to  us  by  others  within  those  entities,
particularly during the period in which this report is being prepared;

(b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under
our  supervision,  to  provide  reasonable  assurance  regarding  the  reliability  of  financial  reporting  and  the  preparation  of  financial
statements for external purposes in accordance with generally accepted accounting principles;

(c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about
the  effectiveness  of  the  disclosure  controls  and  procedures,  as  of  the  end  of  the  period  covered  by  this  report  based  on  such
evaluation; and

(d) disclosed  in  the  report  any  change  in  the  registrant’s  internal  control  over  financial  reporting  that  occurred  during  the  registrant’s
most  recent  fiscal  quarter  (the  registrant’s  fourth  fiscal  quarter  in  the  case  of  an  annual  report)  that  has  materially  affected,  or  is
reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

(5) The  registrant’s  other  certifying  officer(s)  and  I  have  disclosed,  based  on  our  most  recent  evaluation  of  internal  control  over  financial
reporting,  to  the  registrant’s  auditors  and  the  audit  committee  of  the  registrant’s  board  of  directors  (or  persons  performing  the  equivalent
functions):

(a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) any  fraud,  whether  or  not  material,  that  involves  management  or  other  employees  who  have  a  significant  role  in  the  registrant’s

internal control over financial reporting.

222
Dated: March 29, 2023

By: /s/ Manuel Litchman
  Manuel Litchman, M.D.

President and Chief Executive Officer
(Principal Executive Officer)

 
 
 
 
 
CERTIFICATION PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002 

EXHIBIT 31.2

I, Eliot Lurier, Interim Chief Financial Officer (Principal Financial Officer), certify that:

(1)

I have reviewed this Annual Report on Form 10-K for the year ended December 31, 2022 of Mustang Bio, Inc. (the registrant);

(2) Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered
by this report;

(3) Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects,

the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

(4) The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined
in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and
15d-15(f)) for the registrant and have:

(a) designed  such  disclosure  controls  and  procedures,  or  caused  such  disclosure  controls  and  procedures  to  be  designed  under  our
supervision,  to  ensure  that  material  information  relating  to  the  registrant  is  made  known  to  us  by  others  within  those  entities,
particularly during the period in which this report is being prepared;

(b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under
our  supervision,  to  provide  reasonable  assurance  regarding  the  reliability  of  financial  reporting  and  the  preparation  of  financial
statements for external purposes in accordance with generally accepted accounting principles;

(c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about
the  effectiveness  of  the  disclosure  controls  and  procedures,  as  of  the  end  of  the  period  covered  by  this  report  based  on  such
evaluation; and

(d) disclosed  in  the  report  any  change  in  the  registrant’s  internal  control  over  financial  reporting  that  occurred  during  the  registrant’s
most  recent  fiscal  quarter  (the  registrant’s  fourth  fiscal  quarter  in  the  case  of  an  annual  report)  that  has  materially  affected,  or  is
reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

(5) The  registrant’s  other  certifying  officer(s)  and  I  have  disclosed,  based  on  our  most  recent  evaluation  of  internal  control  over  financial
reporting,  to  the  registrant’s  auditors  and  the  audit  committee  of  the  registrant’s  board  of  directors  (or  persons  performing  the  equivalent
functions):

(a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) any  fraud,  whether  or  not  material,  that  involves  management  or  other  employees  who  have  a  significant  role  in  the  registrant’s

internal control over financial reporting.

22
Dated: March 29, 2023

By: /s/ Eliot Lurier
Eliot Lurier
Interim Chief Financial Officer
(Principal Financial Officer)  

 
 
 
 
 
 
CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 

EXHIBIT 32.1

In connection with the Annual Report on Form 10-K of Mustang Bio, Inc. (the “Company”) for the period ended December 31, 2022, as filed
with  the  Securities  and  Exchange  Commission  on  the  date  hereof  (the  “Report”),  I,  Manuel  Litchman,  M.D.,  President  and  Chief  Executive
Officer, hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my
knowledge:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)  The  information  contained  in  the  Report  fairly  presents,  in  all  material  respects,  the  financial  condition  and  results  of  operations  of  the
Company as of, and for, the periods presented in the Report.

Dated: March 29, 2023

By: /s/ Manuel Litchman
  Manuel Litchman, M.D.,

President and Chief Executive Officer
(Principal Executive Officer)

 
 
 
 
 
 
CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

EXHIBIT 32.2

In connection with the Annual Report on Form 10-K of Mustang Bio, Inc. (the “Company”) for the period ended December 31, 2022, as filed
with the Securities and Exchange Commission on the date hereof (the “Report”), I, Eliot Lurier, Interim Chief Financial Officer, hereby certify,
pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)  The  information  contained  in  the  Report  fairly  presents,  in  all  material  respects,  the  financial  condition  and  results  of  operations  of  the
Company, as of, and for, the periods presented in the Report.

Dated: March 29, 2023

By: /s/ Eliot Lurier
Eliot Lurier
Interim Chief Financial Officer
(Principal Financial Officer)