Enanta Pharmaceuticals, Inc. Annual Report 2023

FY2023 Annual Report · Enanta Pharmaceuticals, Inc.

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Annual Report 2023

TO OUR SHAREHOLDERS,

January 16, 2024

At Enanta, we are
always working toward
our mission to discover,
develop and deliver
groundbreaking small
for
molecule drugs
diseases with significant unmet need, and 2023
was an important year that advanced that
mission. Reflecting on all that we accomplished
this year, we made headway to achieve our
goal by expanding our focus beyond virology,
positioning Enanta for a transformative 2024
and beyond.

At the center of our mission is our wholly-
owned, clinical-stage pipeline, which is built
upon years of drug discovery experience
and
includes one of the most advanced
respiratory syncytial virus (RSV) treatment
portfolios in development today. We believe
there is a significant unmet need for RSV
treatments, despite the availability of vaccines
and prophylactic monoclonal antibodies that
reduce the risk of infection for some high-
risk populations. As such, we are progressing
multiple clinical studies to address this unmet
need, and are evaluating zelicapavir (EDP-938),
an N-protein inhibitor, with two ongoing Phase
2 trials, RSVPEDs and RSVHR, and EDP-323,
an L-protein inhibitor, with a Phase 2a human
challenge study. For RSVPEDs, our Phase 2
study in pediatric RSV patients, and RSVHR,
our Phase 2 study in adults at high risk for
complications from RSV, we focused our efforts
to expand the global footprint of our clinical
trial sites. If we continue to have a normal RSV
season in the Northern Hemisphere this winter,
we expect to enroll one or both of these trials
of zelicapavir and to report data in the third
quarter of 2024.

Also in our RSV portfolio, this spring we
announced positive results from our Phase 1

study of EDP-323, which was found to be
generally safe and well-tolerated in healthy
subjects with dosing up to 800mg and
pharmacokinetics supportive of once-daily
dosing. Based on these results, in November
we initiated a Phase 2a human challenge
study of EDP-323, designed to evaluate
safety, changes in viral load measurements
and changes in baseline symptoms compared
to placebo. We believe either zelicapavir or
EDP-323 would be effective as a monotherapy,
and because the mechanism of action
is
different for each, we may also be able to use
them in combination to broaden the treatment
window or addressable patient population.

This year we made important adjustments
to our business to significantly reduce our
2024 spending and extend our cash runway
through fiscal 2027. We made the decision
to stop RSVTx, our Phase 2 study in adult
hematopoietic stem cell transplant recipients
with RSV infection. We felt it prudent to
concentrate our efforts and resources on our
pediatric and high-risk adult studies, which
comprise the largest patient populations with
unmet need and represent the faster paths to
market. We also paused our hMPV/RSV dual-
inhibitor program. While the dual-inhibitor has
shown significant promise preclinically, we do
not plan to move a third RSV compound into the
clinic as long as our other two more advanced
RSV candidates continue to progress.

In our COVID-19 program, we were pleased
by the positive Phase 2 SPRINT (SARS-Cov-2
PRotease INhibitor Treatment) study results for
EDP-235, our oral 3CL protease inhibitor with
FDA Fast Track designation. In SPRINT, 400mg
of EDP-235 demonstrated an improvement
in total symptom score, achieving statistical
significance at multiple time points, as well as
a virologic effect in the subset of patients who

sales of MAVYRET®/MAVIRET®, which remains
a leading treatment for hepatitis C virus (HCV).
MAVYRET®/MAVIRET® has been remarkably
impactful for many, curing over a million
people afflicted with the virus. We expect this
important drug will continue to play a critical
role in treating millions still infected with HCV.

As we look ahead to 2024, we are pleased
to be in a strong position for growth, with
multiple milestones expected across our new
and ongoing programs. I would like to thank
our employees for their continued dedication to
Enanta. Their diligence and dedication are what
propels us, allowing for continued progress.
And importantly, to our shareholders, to whom
we owe our sincere gratitude. We thank you
for the opportunity to execute our mission
of developing transformative medicines and
appreciate your support to do so.

Sincerely,

Jay R. Luly, Ph.D.
President and Chief Executive Officer

had not been recently infected. As part of our
business and cash prioritization plans, we made
the decision to pursue any future COVID-19
efforts only in the context of a collaboration.

Regarding our hepatitis B virus (HBV) program,
we believe we need an additional mechanism
to develop in combination with EDP-514, our
potent core inhibitor with FDA Fast Track
designation. We think a core inhibitor such
as EDP-514 could ultimately be an important
component of a successful combination regimen
and potentially help address the high level of
unmet need in chronic HBV. As such, advancing
this program is dependent upon accessing an
additional mechanism through licensing or a
collaboration to bring a cure to market.

Beyond virology, this month we announced
plans to
leverage our small molecule
development expertise to diversify our pipeline
and expand into new non-virologic indications,
starting with
immune-mediated chronic
diseases. Our first program is investigating
prototype KIT inhibitors as a potential
treatment for chronic spontaneous urticaria
(CSU), a severely debilitating inflammatory skin
disease. We are currently optimizing leads and
plan to announce a development candidate
in 2024.

This year we also took steps to strengthen
our balance sheet. In April 2023, we sold
54.5% of our ongoing MAVYRET®/MAVIRET®
(glecaprevir/pibrentasvir) royalties from AbbVie
for an upfront payment of $200 million from
OMERS, one of Canada’s largest defined benefit
pension plans. We retain 45.5% of all royalties
until 1.42x cap is hit, at which point 100% of all
further royalties revert to Enanta.

Enanta had $370 million in cash and marketable
securities as of September 30, 2023, our fiscal
year-end. In our 2023 fiscal year, we earned
$78.2 million in royalty revenue from AbbVie’s

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 September 30, 2023
OR

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

EXCHANGE ACT OF 1934

Commission File Number 001-35839

ENANTA PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

DELAWARE
(State or other jurisdiction of
incorporation or organization)

2834
(Primary Standard Industrial
Classification Code Number)

04-3205099
(I.R.S. Employer
Identification Number)

500 Arsenal Street
Watertown, Massachusetts 02472
(617) 607-0800
(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)
Securities registered pursuant to Section 12(b) of the Act:
Trading Symbol(s)
ENTA
Securities registered pursuant to Section 12(g) of the Act: None

Name of each exchange on which registered
NASDAQ

Title of each class
Common Stock, par value $0.01 per share

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

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐ No ☒
Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that 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 registrant’s 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, March 31, 2023, based on the last reported sale price of the registrant’s common stock of $40.44 per share
was $799,700,757. The number of shares of the registrant’s Common Stock, $0.01 par value, outstanding as of November 1, 2023 was 21,058,925 shares.
DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s Definitive Proxy Statement for its 2024 Annual Meeting of Stockholders scheduled to be held on March 6, 2024, which

Definitive Proxy will be filed with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of September 30,
2023 are incorporated by reference into Part III of this Form 10-K.

As used in this Form 10-K, “Enanta,” “the Company,” “we,” “our,” and “us” refer to Enanta Pharmaceuticals, Inc.,
and “MAVYRET/MAVIRET” refers to AbbVie’s HCV regimen consisting of tablets of glecaprevir/pibrentasvir,
except where the context otherwise requires or as otherwise indicated. MAVYRET®, MAVIRET®, VIEKIRA
PAK®, VIEKIRAX® and EXVIERA® are trademarks of AbbVie, Inc.

NOTE REGARDING FORWARD LOOKING STATEMENTS

This Annual Report on Form 10-K contains forward-looking statements concerning our business, operations and
financial performance and condition, as well as our plans, objectives and expectations for our business operations
and financial performance and condition. Any statements contained herein that are not statements of historical facts
may be deemed to be forward-looking statements. In some cases, you can identify forward-looking statements by
terminology such as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “due,”
“estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “predict,” “potential,” “positioned,” “seek,”
“should,” “target,” “will,” “would,” and other similar expressions that are predictions of or indicate future events
and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements
include, but are not limited to, statements about overall trends, royalty revenue trends, research and clinical
development plans, liquidity and capital needs and other statements of expectations, beliefs, future plans and
strategies, anticipated events or trends and similar expressions. These forward-looking statements are based on our
management’s current expectations, estimates, forecasts and projections about our business and the industry in
which we operate and our management’s beliefs and assumptions. These forward-looking statements are not
guarantees of future performance or development and involve known and unknown risks, uncertainties and other
factors that are in some cases beyond our control. As a result, any or all of our forward-looking statements in this
Annual Report on Form 10-K may turn out to be inaccurate. Factors that may cause actual results to differ materially
from current expectations include, among other things, those listed under “Risk Factors” and discussed elsewhere in
this Annual Report on Form 10-K. These forward-looking statements speak only as of the date of this Annual Report
on Form 10-K. Except as required by law, we assume no obligation to update or revise these forward-looking
statements for any reason, even if new information becomes available in the future. You should, however, review
the factors and risks we describe in the reports we will file from time to time with the SEC after the date of this
Annual Report on Form 10-K.

ENANTA PHARMACEUTICALS, INC.

ANNUAL REPORT ON FORM 10-K

For the year ended September 30, 2023

INDEX

Item No.

Page

Summary of Principal Risk Factors ..........................................................................................................

1.
1A.
1B.
2.
3.
4.

6.
7.
7A.
8.
9.
9A.
9B.
9C.

10.
11.
12.
13.
14.

15.
16.

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

PART II

Market for the Company’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...................................................................
Consolidated Financial Statements and Supplementary Data ..................................................................
Changes in and Disagreements with Accountants on Accounting and Financial Disclosure ..................
Controls and Procedures ...........................................................................................................................
Other Information .....................................................................................................................................
Disclosure Regarding Foreign Jurisdictions that Prevent Inspections .....................................................

PART III
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 Accounting Fees and Services...................................................................................................

PART IV
Exhibits and Financial Statement Schedules ............................................................................................
Form 10-K Summary ................................................................................................................................
Signatures .................................................................................................................................................

3
26
48
48
48
48

49
50
51
60
60
60
60
61
61

62
62
62
63
63

64
66
67

[THIS PAGE INTENTIONALLY LEFT BLANK]

SUMMARY OF PRINCIPAL RISK FACTORS

This summary briefly states the principal risks and uncertainties facing our business that could affect our common stock, which are
only a select portion of those risks. A more complete statement of those risks and uncertainties is set forth in the Section 1A “Risk
Factors” of this report. This summary is qualified in its entirety by that more complete statement. You should carefully read the entire
statement and “Risk Factors” when considering the risks and uncertainties as part of your evaluation of an investment in our common
stock.

• We will require substantial additional funding to achieve our goals. If we do not generate sufficient funding from our

existing collaboration and any future collaborations, we will need to obtain additional funding to support our operations.
A failure to obtain funding when needed could force us to delay, limit, reduce or terminate some or all of our product
development efforts.

•

Our revenues for the next several years are substantially dependent upon AbbVie’s success selling
MAVYRET/MAVIRET, which includes our protease inhibitor, glecaprevir, for the treatment of HCV.

•

AbbVie may continue to experience lower sales volume in future quarters, primarily due to a reduction in diagnoses and
treatment rates of HCV.

AbbVie’s MAVYRET/MAVIRET regimen will have to continue to compete successfully against other products and
therapies for HCV, including competition for exclusive arrangements with third-party payors and governmental entities as
well as price competition, both in the U.S. and in other markets worldwide.

After June 30, 2023, 54.5% of our reported revenues will represent payments that go directly to OMERS following our
April 2023 sale of that portion of our MAVYRET/MAVIRET royalties through June 30, 2032, subject to a cap on
aggregate payments to OMERS equal to 1.42 times the purchase price.

There are many companies developing potential therapies for RSV, SARS-CoV-2, and HBV, which may result in others
discovering, developing or commercializing products before we do or doing so more successfully than we do.

•

In most of the disease areas currently the subject of our research and development efforts, there are other companies with
product candidates that are more advanced than ours.

If we are not “first to market” with one of our product candidates in one or more of our targeted disease indications, such
as COVID-19, our competitive position could be compromised because it may be more difficult for us to obtain marketing
approval for that product candidate and/or market acceptance of that product candidate as a follow-on competitor.

Continued changes in royalty revenue earned under our AbbVie agreement or in the level of expenses associated with
our clinical development programs, or both, will cause our results of operations to fluctuate from period to period. Given
the reduction in our retained royalty revenue following our royalty sale, combined with increasing research and
development expenses in support of our advancing programs, we expect to have continuing operating losses for the
foreseeable future.

•

Many of the preclinical and clinical development activities required for our product candidates must be contracted out to
contract research organizations, or CROs, at significant expense. We expect these expenses to increase substantially in the
coming years if we are able to advance any of our compounds into registrational clinical studies, as well as any impact of
inflation, the combination of which will likely result in continuing operating losses.

Clinical drug development for viral infections involves a lengthy and expensive process with uncertain timelines,
uncertain outcomes and evolving clinical endpoints for regulatory approvals. If clinical trials of any of our proprietary
product candidates are prolonged or delayed, we may be unable to commercialize our product candidates on a timely
basis.

•

None of our product candidates in our clinical development pipeline has yet to advance beyond Phase 2 clinical trials.

Some of our RSV clinical trials may be delayed if future incidence of RSV does not return to pre-pandemic patterns.

Changes in regulatory requirements, policies and guidelines, including guidelines specifically addressing requirements for
the development of treatments for RSV, SARS-CoV-2 or HBV could also delay the time required to reach approval of one
or more of our product candidates.

•

The results of clinical trials are inherently uncertain. The results of preclinical studies and early clinical trials of our
product candidates may not be predictive of the results of later-stage clinical trials, if any, including sufficient efficacy
and an acceptable safety and tolerability profile.

•

Several companies in the disease areas we are seeking to address have suffered significant setbacks in advanced clinical
trials due to adverse safety profiles or lack of efficacy, notwithstanding promising results in earlier studies.

Clinical trials involving our product candidates may be suspended or terminated at any time for a number of safety-related
reasons. For example, administering any product candidate to humans may produce undesirable side effects not identified
in preclinical studies.

We may choose to test any of our clinical candidates preclinically and/or clinically in combination with other compounds
with different mechanisms of action. Any adverse results from such testing may have adverse consequences for the further
development potential of not only the combination but also the clinical candidate itself as a monotherapy or in
combination with other mechanisms of action.

• We may delay or terminate the development of a product candidate at any time if we believe the perceived market or

commercial opportunity does not justify further investment.

• We could be unsuccessful in obtaining or maintaining adequate patent protection for one or more of our product

candidates.

•

We are competing to develop intellectual property in areas of small-molecule drug development that are highly
competitive.

We cannot be certain that patents will be issued or granted with respect to our patent applications that are currently
pending, or that issued or granted patents will not later be found to be invalid and/or unenforceable, be interpreted in a
manner that does not adequately protect our products, or otherwise fail to provide us with any competitive advantage.

• We rely on third parties to manufacture our clinical drug supplies, monitor, support, conduct and/or oversee clinical

trials of our product candidates that we develop independently.

ITEM 1.

BUSINESS

Overview

PART I

BUSINESS

We are a biotechnology company that uses our robust, chemistry-driven approach and drug discovery capabilities to become a leader
in the discovery and development of small molecule drugs with an emphasis on treatments for viral infections. We discovered
glecaprevir, the second of two protease inhibitors discovered and developed through our collaboration with AbbVie for the treatment
of chronic infection with hepatitis C virus, or HCV. Glecaprevir is co-formulated as part of AbbVie’s leading brand of direct-acting
antiviral, or DAA, combination treatment for HCV, which is marketed under the tradenames MAVYRET® (U.S.) and MAVIRET®
(ex-U.S.) (glecaprevir/pibrentasvir). Our ongoing royalties from our AbbVie collaboration, combined with the proceeds from our
April 2023 royalty sale transaction, have provided us funding to support our wholly-owned research and development programs,
which are primarily focused on the following disease targets:

•

Respiratory syncytial virus, or RSV, the most common cause of bronchiolitis and pneumonia in young children and a
significant cause of respiratory illness in older adults, with estimates suggesting that on average each year RSV leads to 3
million hospitalizations globally in children under 5 years old and 60,000-160,000 adults over the age of 65 in the U.S. are
hospitalized and 6,000-10,000 die due to RSV infections;

SARS-CoV-2, the virus that causes COVID-19, with estimates suggesting that COVID-19 continues to have a disease
burden greater than influenza, including persistent cases of infection often referred to as long COVID and hospitalization
and death among the elderly and those with comorbidities, while new variants continue to emerge on a regular basis; and

Hepatitis B virus, or HBV, the most prevalent chronic hepatitis, which is estimated by the World Health Organization to
affect close to 300 million individuals worldwide.

Since fiscal 2020, we have reported net losses. We generated revenue of $79.2 million and $86.2 million for the years ended
September 30, 2023 and 2022, respectively, and incurred net losses of $133.8 million and $121.8 million for those same periods.
Going forward, we will receive only 45.5% of ongoing royalty payments from AbbVie following our April 2023 royalty sale
transaction that provided us a payment of $200.0 million. We expect to continue to incur net losses for the foreseeable future. As a
result, we expect to need additional funding for expenses related to our ongoing operations.

As of September 30, 2023, we had $369.9 million in cash, cash equivalents and short-term marketable securities. We expect that our
existing cash, cash equivalents, short-term marketable securities and our continuing portion of HCV royalties, will enable us to fund
our operating expenses and capital expenditure requirements through fiscal 2027. We have based this estimate on assumptions that
may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. See “Liquidity and Capital
Resources.”

Because of the numerous risks and uncertainties associated with clinical development and commercialization, we are unable to
accurately predict the timing or amount of increased expenses or when, or if, we will be able to achieve or maintain profitability. Until
such time, if ever, as we can generate substantial revenue sufficient to achieve profitability, we expect to finance our operations
through a combination of equity offerings, non-dilutive financings, collaborations, strategic alliances or licensing agreements. We may
be unable to raise additional funds or enter into such other agreements or arrangements, when needed, on favorable terms, or at all. If
we are unable to raise capital or enter into such agreements as, and when, needed, we may have to significantly delay, scale back or
discontinue the further development and commercialization efforts of one or more of our products, or may be forced to reduce or
terminate our operations.

Our Wholly-Owned Programs

Our primary wholly-owned research and development programs are in virology, namely RSV, SARS-CoV-2 and HBV:

•

RSV: We have a clinical stage program for RSV, with two compounds in clinical trials – EDP-938 and EDP-323. EDP-
938, which has Fast Track designation from the U.S. Food and Drug Administration, or FDA, is a potent inhibitor of N-
protein activity for both major subgroups of RSV, referred to as RSV-A and RSV-B. It is currently in two ongoing Phase
2 studies, each in a different patient population. We completed a Phase 1 clinical study of EDP-323, an inhibitor of the
RSV L-protein with Fast Track designation from the FDA, with positive topline results reported in June 2023. We
initiated a Phase 2 challenge study of EDP-323 in the fourth quarter of calendar 2023.



EDP-938 - N-protein Inhibitor Candidate: We have studied EDP-938 in two Phase 2 studies that were designed to
be proof-of-concept and exploratory studies to understand better the viral response in the context of RSV infection.

These studies were conducted in otherwise healthy adults (not at high-risk for serious outcomes with RSV) infected
with RSV. The first study was a challenge study, in which healthy adults were infected with RSV in a clinical
setting. The second study, known as RSVP, was in an otherwise healthy adult outpatient population with
community-acquired RSV infection. With these studies, EDP-938 has demonstrated a favorable safety profile,
consistent with that observed in over 500 subjects exposed to EDP-938 to date. We believe that EDP-938 has the
greatest potential to show optimal efficacy in high-risk populations since these patients have reduced RSV
immunity, which manifests in a higher and longer duration of viral load and greater disease severity, allowing a
bigger window to realize the full potential of EDP-938. Based on the efficacy and growing safety profile of EDP-
938, we are continuing to evaluate EDP-938 in high-risk populations in the following ongoing clinical studies,
including pediatric patients and high-risk adults, all of which have significant unmet need:

▪

RSVPEDs: RSVPEDs is a Phase 2 study in pediatric patients. This dose-ranging, randomized, double-blind,
placebo-controlled study, is evaluating multiple ascending doses for five days in two age cohorts to determine
safety, tolerability, and pharmacokinetics, as well as a second part evaluating antiviral activity at the selected
dose.

RSVHR: RSVHR is a Phase 2b study in high-risk adults, including those who are older than 65 years of age
and those who have asthma, chronic obstructive pulmonary disease, or COPD, or congestive heart failure.
Approximately 180 patients will be treated with EDP-938 or placebo for five days with a primary endpoint of
time to resolution of RSV lower respiratory tract disease symptoms.

Next steps: We expect to complete enrollment in one or both of our ongoing Phase 2 studies of EDP-938 in
the 2023-2024 Northern Hemisphere RSV season and to report data in the third quarter of calendar 2024,
assuming there is a normal, pre-pandemic type of RSV season in the Northern Hemisphere.

EDP-323 - L-protein Inhibitor Candidate: Our second clinical RSV candidate, EDP-323, is a novel oral, direct-
acting antiviral selectively targeting the RSV L-protein, a viral RNA-dependent RNA polymerase enzyme that
contains multiple enzymatic activities required for RSV replication. EDP-323 has sub-nanomolar potency against
RSV-A and RSV-B in vitro and protected mice in a dose-dependent manner from RSV infection as demonstrated by
both virological and pathological endpoints. EDP-323 is not expected to have cross-resistance to other classes of
inhibitors and has the potential to be used alone, or in combination with other RSV mechanisms, to broaden the
treatment window or addressable patient populations. In June 2023, we completed a Phase 1 clinical study and
reported positive topline results, which demonstrated that EDP-323 was safe and well-tolerated with
pharmacokinetics supportive of once-daily dosing with target exposures achieved and no food effect. Based on
these positive data, we initiated a Phase 2 challenge study of EDP-323 in the fourth quarter of calendar 2023 and
expect topline data in the third quarter of calendar 2024.

RSV/hMPV Dual-Inhibitor: We have a research program targeting development of single agents with broader
spectrum antiviral activity against both RSV and human metapneumovirus, or hMPV, a virus that is a significant
cause of respiratory tract infections similar to those caused by RSV. These target compounds, which we refer to as
dual-inhibitors, maintained activity against multiple genotypes and strains of RSV and hMPV in a range of cell
types in preclinical studies, and blocked replication in a dose-dependent manner in respective mouse models of each
virus. We have paused this research program as we do not plan to advance a third RSV candidate into the clinic as
long as EDP-938 and EDP-323 continue to progress into further clinical development.



•

COVID-19: We have leveraged our expertise in developing protease inhibitors to discover compounds specifically
designed to target the SARS-CoV-2 virus and potentially other coronaviruses.



EDP-235 – Protease Inhibitor Candidate: EDP-235 is an oral inhibitor of the coronavirus 3CL protease, also
referred to as 3CLpro or the main coronavirus protease, or Mpro, which has been granted Fast Track designation by
the FDA. In addition to nanomolar activity against all SARS-CoV-2 variants tested to date, EDP-235 has potent
antiviral activity against other human coronaviruses, enabling the potential for a pan-coronavirus treatment,
including possibly coronaviruses that may infect human populations in the future. Furthermore, EDP-235 has good
tissue distribution, and is projected to have four times higher drug levels in lung tissue compared to plasma and has
demonstrated high cell penetration rates in many cell types studied to date in vitro. A robust treatment effect and
prevention of transmission was observed in a ferret model.

▪

and well-tolerated in doses up to 400 mg for seven days and adverse events were infrequent and mild.
Pharmacokinetics were supportive of once-daily dosing without ritonavir and without regard to food and
achieved target exposure levels of up to 13-fold over the plasma protein-adjusted EC90.

Phase 2 Study: In May 2023, we reported topline results from SPRINT (SARS-CoV-2 Protease Inhibitor
Treatment), a Phase 2 clinical trial of EDP-235. This randomized, double-blind, placebo-controlled study
evaluated the safety, tolerability, antiviral activity and clinical symptoms of EDP-235 compared to placebo in
approximately 230 non-hospitalized, symptomatic patients with mild to moderate COVID-19 who were not at
increased risk for developing severe disease. Patients were eligible to participate if they had symptoms for
five days or less and had not received a SARS-CoV-2 vaccine or been infected with SARS-CoV-2 within 90
days of enrollment. Patients received either 200 mg or 400 mg EDP-235 or placebo orally with food once
daily for five days. EDP-235 met the primary endpoint of the trial and was generally safe and well-tolerated.
A dose-dependent improvement in total symptom score was observed with EDP-235 treatment compared to
placebo, which achieved statistical significance (p<0.05) in the 400 mg treatment group at multiple time
points, starting as early as one day after the first dose. While no difference was observed in time to
improvement in the overall group of 14 measured COVID-19 symptoms, an analysis of a subset of six
symptoms showed a two-day shorter time to improvement in patients receiving EDP-235 400 mg who were
enrolled within three days of symptom onset (p<0.01). No effect on virologic endpoints as measured in the
nose was detected due to the rapid viral decline in the placebo arm of this highly immunologically-
experienced, standard risk population. However, in the subset of patients who were nucleocapsid seronegative
(indicating no recent natural infection with SARS-CoV-2), a viral load decline was observed at day five in the
400 mg group of 0.8 log overall and 1 log in the patients with symptom onset within three days before
treatment with EDP-235.

▪

Next Steps: Going forward, we will continue to focus on potential collaborations to progress EDP-235, as we
will not advance this candidate further on our own.

•

HBV: Our lead clinical candidate for the treatment of chronic infection with hepatitis B virus, or HBV, is EDP-514, a core
inhibitor that displays potent anti-HBV activity in vitro at multiple points in the HBV lifecycle. Our goal is to develop a
combination therapy approach, including existing approved treatments such as a nucleoside reverse transcriptase inhibitor,
or NUC, with EDP-514 and one or more other mechanisms, which could lead to a functional cure for patients with chronic
HBV infection. Advancement of this program is dependent upon our accessing another compound that could be developed
with EDP-514 for such a treatment regimen.



EDP-514 - Core Inhibitor Candidate: Final data from two Phase 1b studies of EDP-514 demonstrate the compound
is safe with strong antiviral activity in two different chronic HBV patient populations – those who have a high viral
load and those who are on a treatment with a nucleoside reverse transcriptase inhibitor. Based on these data, we
remain convinced that EDP-514, which has Fast Track designation, has the potential to be a best-in-class core
inhibitor for HBV.

We have utilized our internal chemistry and drug discovery capabilities to generate all of our development-stage programs. We
continue to invest substantial resources in research programs to discover compounds targeting new disease areas.

Our Out-Licensed Products

HCV: Two protease inhibitors developed through our Collaborative Development and License Agreement with AbbVie have been
clinically tested, manufactured, and commercialized by AbbVie as part of its combination regimens for HCV. We have received the
full $330.0 million of contractual milestone payments under the agreement related to clinical development and commercialization
regulatory approvals of these regimens in major markets, and we continue to earn royalties on sales of those regimens.

Glecaprevir is the HCV protease inhibitor we discovered that was developed by AbbVie in a fixed-dose combination with its NS5A
inhibitor, pibrentasvir, for the treatment of chronic HCV. This patented combination, currently marketed under the brand names
MAVYRET® (U.S.) and MAVIRET® (ex-U.S.), is referred to in this report as MAVYRET/MAVIRET. This regimen is a once-daily,
all-oral, fixed-dose, ribavirin-free treatment for HCV genotypes 1-6, or GT1-6, which is referred to as being pan-genotypic. In the
U.S., EU and Japan it is approved as an 8-week treatment for patients with and without compensated cirrhosis and new to treatment.
Today, these patients are estimated to represent the majority of HCV patients in over 50 countries where MAVYRET/MAVIRET is
sold by AbbVie and where MAVYRET/MAVIRET remains the only 8-week pan-genotypic HCV treatment. The first protease
inhibitor developed through this collaboration, paritaprevir, is part of Abbvie’s initial HCV regimens, which have been almost entirely
replaced by MAVYRET/MAVIRET. Since August 2017, substantially all of our royalty revenue has been derived from AbbVie’s net
sales of MAVYRET/MAVIRET. Our ongoing royalty revenues from this regimen consist of annually tiered, double-digit, per-product
royalties on 50% of the calendar year net sales of the 2-DAA glecaprevir/pibrentasvir combination in MAVYRET/MAVIRET. The
annual royalty tiers return to the lowest tier for sales on and after each January 1. In April 2023, we sold 54.5% of our future

MAVYRET/MAVIRET royalties for a $200.0 million cash payment, subject to a cap of total royalties sold equal to 1.42 times the
cash payment.

Our Strategy

Our primary objective is to become a leader in the discovery and development of small molecule drugs with an emphasis on
treatments for viral infections and to provide new therapies for patients with unmet medical needs. Our focus has primarily been on
antiviral targets for viruses such as RSV, SARS-CoV-2, and HBV, which in most cases are therapeutic areas that have attracted
research and development efforts of many competitors. Our strategy includes the following key elements:

•

Advance clinical development of novel virology product candidates for RSV. We have ongoing clinical studies of two
compounds discovered in our research program in RSV, a viral infection for which there is currently no available effective
treatment and as such there exists a substantial unmet medical need.

Invest in research and development of compounds in new disease areas. We are continuing to invest resources in our
research programs in our efforts to identify and advance additional novel compounds that have the potential to address
significant unmet medical needs in new disease areas. We may also explore clinically other diseases where our assets
could play a role. In addition, we may seek to augment our product candidate pipeline through the acquisition or in-
licensing of external assets and/or technologies in one or more of our disease areas of focus.

Collaborate or out-license, where and when appropriate, with pharmaceutical partners to create combination therapies
and/or accelerate the development and commercialization of our proprietary compounds. We are prepared to join forces,
where and when appropriate, with collaborators with compounds targeting other mechanisms of action in diseases such as
HBV, where there is the potential for better treatments with combination therapies. We may also choose to collaborate
with other companies to accelerate the global clinical development of our product candidates. Our decisions regarding our
proprietary programs will be based on the results of our early phase clinical studies and the potential for collaborations,
including combinations with one or more drugs targeting other mechanisms of action in these diseases.

Continue to use our existing resources and future cash flow from our AbbVie collaboration to fund our research and
development activities. We expect our existing financial resources and our retained portion of future royalty payments
from our AbbVie collaboration will provide us resources to fund our research and development programs through fiscal
2027. These resources will allow us to continue to advance compounds in clinical development and to progress the most
promising candidates at least through proof-of-concept trials. Further development of any compound as a monotherapy or
in combinations with other therapeutic agents when we believe such combinations will provide the most promising
opportunities will require additional financial resources.

Our Research and Development Pipeline

The following table summarizes our product development pipeline in our virology programs:

Our RSV Program

Background and Overview of RSV

Respiratory syncytial virus, or RSV, is a virus that infects the lungs and is the most common cause of bronchiolitis and pneumonia in
young children and a significant cause of respiratory illness in older adults. Almost all children are infected at least once before they
are 2 years old, and about a half are infected twice, resulting in over 2 million outpatient visits in young children. According to the
most recent data from the Centers for Disease Control and Prevention (CDC), two to three out of every 100 infants with an RSV
infection may need to be hospitalized. Hospitalization rates due to RSV are approximately 16 times higher than for influenza among
children aged less than 1 year. The CDC currently estimates that each year 60,000-160,000 older adults in the United States are
hospitalized due to RSV infections. RSV is estimated to cause 100–500 deaths annually in children under 5 years old and 6,000-
10,000 deaths annually in adults over 65 years old in the U.S. There are currently no safe and effective therapies for RSV infection.

Synagis, a prophylactic, monoclonal antibody-based treatment is approved for infants considered at high risk for RSV infection;
however, studies have found that most young children with RSV infection were previously healthy, and thus would not normally be
prescribed this prophylactic treatment. AstraZeneca and Sanofi (Beyfortus/nirsevimab – approved in U.S./EU) have long-acting
monoclonal antibody products recently approved for prophylaxis use in all infants and for those at risk up to 24 months of age and
Merck (clesrovimab) has a similar antibody in Phase 3 development. A maternal vaccine has been approved for injection in women at
32-36 weeks (U.S.) & 24-36 weeks (EU) of pregnancy during September through January (ABRYSVO/Pfizer). In addition, two RSV
vaccines have been approved in adults older than 60 years old (ABRYSVO/Pfizer and AREXVY/GSK) and another vaccine is in
Phase 3 development (Moderna/mRNA-1345).

While prophylaxis options have recently become available, there is still significant unmet need for safe and effective antiviral
treatments in patients at high-risk for serious outcomes of RSV. The adoption of vaccines in the elderly population is likely to be sub-
optimal, especially as recommended with shared clinical decision-making. For perspective, universally recommended vaccines in this
population have peak adoption rates from ~35% (shingles) to ~55% (flu). However, even with adoption, breakthrough infections will
still occur, as efficacy is not complete. In the pediatric population, both the maternal vaccine and the prophylactic antibody approaches
provide only passive immunity, and will just shift the time of first RSV infection to the next season. Similarly, uptake of these options
will not be optimal and breakthrough infections will still occur in the population that does receive them. Finally, the antibody
approach has a low barrier to the development of viral resistance. Thus, despite these options for prophylaxis, antiviral treatments are
urgently needed.

Scientific Background

RSV is a single-stranded, negative-sense RNA virus. There are two major subgroups of RSV, designated RSV-A and RSV-B, each of
which contains numerous genotypes. Both groups are viewed as capable of causing RSV infections that can result in hospitalization.
The RSV genome consists of ten genes that encode for 11 proteins, namely NS1, NS2, N, P, M, SH, G, F, M2-1, M2-2, and L. The F
and G proteins are the predominant target proteins for RSV vaccines. Similarly, small molecule therapeutics have focused primarily
on the F (or fusion) protein, while some efforts have targeted the N (nucleocapsid) and L (contains viral RNA polymerase) proteins.
Fusion inhibitors work by blocking viral entry, a mechanism that may be less ideal when treatment begins at a time when massive
amounts of viral replication is already ongoing. Additionally, fusion inhibitors have been generally shown to have a lower barrier to
the development of viral resistance when in clinical use. Replication inhibitors (e.g., N and L inhibitors) work by blocking viral
replication at its source, stopping the production on new virions. They have demonstrated a higher bar to the emergence of viral
resistance. While most companies are developing potential approaches geared toward the F-protein (or fusion protein, responsible for
mediating viral entry of RSV into host cells), we are focused on mechanisms, such as the N-protein and L-protein inhibitors, that
target the replication process of RSV directly.

Competitive Landscape

Several companies are seeking to develop antiviral treatments for RSV infection in adult and pediatric patients. Ark Biosciences
(Ziresovir) and Pfizer (sinsunatovir) both have fusion inhibitors in later stage clinical development. Additional companies (eg;
Shionogi) have compounds in Phase 1/2a clinical studies.

EDP-938, Our N-Protein Inhibitor

Through our internal chemistry efforts, we identified our lead clinical candidate, EDP-938. During preclinical studies, EDP-938
demonstrated a greater than 4-log reduction in viral load in an animal model challenged with RSV. Further, EDP-938 maintained
nanomolar antiviral potency across all clinical isolates tested in vitro, as well as virus that was resistant to fusion inhibitors. The
compound inhibited RSV at a post-entry replication step and maintained its activity in vitro when given 24 hours post infection. It was
also shown to have a high barrier to viral resistance. In addition, combination studies of EDP-938 with other types of RSV inhibitors,
such as fusion inhibitors, showed synergistic antiviral effects.

We have studied EDP-938 in two Phase 2 studies that were designed to be proof-of-concept and exploratory studies to understand the
viral response better in the context of RSV infection. These studies were conducted in otherwise healthy adults (not at high-risk for
serious outcomes with RSV) infected with RSV.

•

The first study was a challenge study, in which healthy adults were infected with RSV in a clinical setting. This study was
a randomized, double-blind, placebo-controlled, human challenge study of 115 healthy adult subjects. Data from this
study demonstrated that EDP-938 was safe and well-tolerated and achieved highly statistically significant reductions
(p=<0.001) in RSV viral load and symptoms compared to placebo.

The second study, known as RSVP, was in an otherwise healthy adult outpatient population with community-acquired
RSV infection. In this healthy population, EDP-938 did not meet the primary endpoint of reduction in total symptom score
compared to placebo, or the secondary antiviral endpoints. However, a statistically significant difference in the number of
subjects achieving undetectable RSV RNA at the end of treatment at Day 5 was observed with EDP-938 compared to
placebo (p=0.033). Although patients were treated within 48 hours of symptom onset, the viral load and symptoms had
already peaked and were declining, indicating RSV infection resolves quickly in this otherwise healthy adult population.

EDP-938 has demonstrated a favorable safety profile, consistent with that observed in over 500 subjects exposed to date.
Based on the growing safety profile of EDP-938 and differences in the range of the course of RSV infection in higher risk
populations, which have always been our target populations, we are progressing development of EDP-938 in patients at
high-risk for developing severe infection leading to hospitalization or death. EDP-938 has the greatest potential to show
optimal efficacy in these high-risk populations with significant unmet need, since these patients have reduced RSV
immunity, which manifests in a higher and longer duration of viral replication and greater disease severity, allowing a
bigger window to realize the full potential of EDP-938.

We are now studying EDP-938 in two additional RSV studies in high-risk patient populations:

•

RSVPEDs is a Phase 2 dose-ranging, randomized, double-blind, placebo-controlled study in pediatric patients. We plan to
enroll approximately 90 infants and children aged 28 days to 36 months with RSV-associated respiratory tract infection,
who will be dosed in up to two age cohorts and will receive EDP-938 or a placebo for five days. The study will be
conducted in two parts. Part 1 will evaluate multiple ascending doses in each age cohort, with a primary endpoint of
safety, tolerability, and pharmacokinetics. Part 2 will evaluate the selected dose from Part 1 across the age cohorts, with a
primary endpoint of antiviral activity.

•

RSVHR is a Phase 2b study in high-risk adults, including those who are older than 65 years of age, have asthma, chronic
obstructive pulmonary disease, or COPD, or congestive heart failure. Approximately 180 patients will be treated with 800
mg of EDP-938 or placebo for five days and evaluated for 28 days thereafter. The study will include non-hospitalized
adult subjects with up to 72 hours of respiratory tract infection symptoms who test positive for RSV and negative for
influenza virus and SARS-CoV-2. The primary endpoint of the study is time to resolution of RSV lower respiratory tract
disease symptoms as assessed by the Respiratory Infection Intensity and Impact Questionnaire, or RiiQ™, symptom scale
through Day 33. Secondary endpoints include additional clinical efficacy measures and antiviral activity compared to
placebo, pharmacokinetics, and safety of EDP-938.

EDP-323, Our RSV L-Protein Inhibitor:

In addition to our N-protein inhibitor, EDP-938, our newest clinical candidate for RSV is EDP-323, a novel oral, direct-acting
antiviral selectively targeting the RSV L-protein, a viral RNA-dependent RNA polymerase enzyme that contains multiple enzymatic
activities required for RSV replication. EDP-323 has sub-nanomolar potency against RSV-A and RSV-B in vitro and protected mice
in a dose-dependent manner from RSV infection as demonstrated by both virological and pathological endpoints. EDP-323 is not
expected to have cross-resistance to other classes of inhibitors and has the potential to be used alone, or in combination with other
RSV mechanisms, to broaden the treatment window or addressable patient populations.

We completed a Phase 1 clinical study of EDP-323 in June 2023. This randomized, double-blind, placebo-controlled, first-in-human
Phase 1 study enrolled healthy volunteers to evaluate the safely, tolerability and pharmacokinetics of oral EDP-323 over a range of
single ascending dose (SAD ranging from 50 to 800 mg, n=50) and multiple ascending doses (MAD ranging from 200 to 800 mg for
seven days, n=32) in fasted and fed states.

Overall, EDP-323 was generally safe and well-tolerated up to 800 mg for up to seven days, where most adverse events (AEs) were
mild, and there were no serious or severe AEs. There was one study discontinuation due to syncope, in the SAD/FE group, which was
deemed unlikely to be related to EDP-323. In the MAD phase, three AEs deemed possibly related to EDP-323 were mild, with two
headaches and one gastrointestinal event. There were no discontinuations due to AEs in the MAD phase. EDP-323 displayed
pharmacokinetics supportive of once daily dosing without regard to food.

EDP-323 doses ranging from 200 to 800 mg once-daily resulted in strong EC90 multiples against both RSV-A and RSV-B strains.
Specifically, EDP-323 administered once daily for seven days resulted in C24 (Ctrough) concentrations at steady state of 11- to 44-
fold over the protein adjusted EC90 (0.3 nM) against both RSV-A and RSV-B strains. Based on these positive data, a human challenge
study evaluating EDP-323 was initiated in the fourth quarter of calendar 2023.

Our SARS-CoV-2 Program

Background and Overview of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2, is the virus that causes COVID-19 (coronavirus disease 2019), the
respiratory illness responsible for the COVID-19 pandemic. SARS-CoV-2 is the seventh known coronavirus to infect people, after
229E, NL63, OC43, HKU1, MERS-CoV, and the original SARS-CoV. Patients at higher risk for developing severe complications
from COVID-19 include the elderly and those with underlying medical conditions like cardiovascular disease, diabetes, chronic
respiratory disease, or cancer. As of October 2023, the World Health Organization estimated nearly 7 million deaths have been caused
by COVID-19. There are also many patients who experience continuing effects of COVID-19, often referred to as “long COVID”.
While vaccines that reduce the severity of COVID-19 are available, uptake has not been optimal. In addition, breakthrough infection
occurs in many cases because the vaccines are not completely effective or their effect diminishes over time, especially against
emerging variants. Thus, there remains an urgent need for effective, safe and well-tolerated, conveniently-dosed, once-daily oral
antiviral treatments.

Scientific Background

All coronaviruses have a single-stranded, positive-sense RNA (+ssRNA) genome, which is the largest known genome for an RNA
virus. The overall structure of the SARS-CoV-2 genome is shared with other betacoronaviruses, namely MERS-CoV and SARS-CoV.
The 3C-like protease, or 3CL protease (also known as 3CLpro or the main protease, or Mpro), is essential for viral replication, and is a
highly attractive target for the development of direct-acting antiviral agents.

Competitive Landscape

There have been two Emergency Use Authorizations of oral antiviral treatments for non-hospitalized, high-risk patients with SARS-
CoV-2 infection: PAXLOVID™, a 3CL protease inhibitor (nirmatrelvir) boosted with ritonavir, and LAGEVRIO™ (molnupiravir), a
polymerase inhibitor. Furthermore, PAXLOVID received full FDA approval for commercial sale in May 2023. PAXLOVID is dosed
twice daily in combination with a low dose of ritonavir, which has significant drug-drug interactions with numerous other
medications, known as DDIs, and is not well tolerated by many patients. Thus, there is a significant need for an efficacious, safe, well-

tolerated and conveniently dosed (oral, once-daily) antiviral treatment for COVID-19 with an improved DDI profile. The companies
developing oral direct acting antivirals for SARS-CoV-2 that are currently in global Phase 3 studies include Shionogi, Atea, and
Gilead (an oral formulation of remdesivir).

EDP-235, Our Lead, Oral, 3CL Protease Inhibitor

Our lead clinical candidate for COVID-19 is EDP-235, an oral, selective inhibitor of coronavirus 3CL pro, which has been granted
Fast Track designation from the FDA. In addition to nanomolar activity against all SARS-CoV-2 variants tested to date, EDP-235 has
potent antiviral activity against other human coronaviruses, enabling the potential for a pan-coronavirus treatment, including possibly
coronaviruses that may infect human populations in the future. Furthermore, EDP-235 has good target tissue distribution and is
projected to have four times higher drug levels in lung tissue compared to plasma. EDP-235 demonstrated a robust treatment effect
and prevention of transmission in a ferret model.

Clinical studies of EDP-235 consist of the following:

•

Phase 1 Study: In July 2022, we completed a Phase 1 study of EDP-235 and reported positive topline results. This first-
in-human, randomized, double-blind, placebo-controlled study enrolled healthy volunteers to evaluate the safety,
tolerability, and pharmacokinetics of oral EDP-235 in single ascending doses and multiple ascending doses for seven
days, and the effect of food. Data from the Phase 1 study demonstrated EDP-235 was generally safe and well-tolerated up
to 400 mg for seven days with infrequent adverse events, the majority of which were mild. Results demonstrated strong
exposure multiples over the EC90, which is a measure of potency, specifically the concentration of drug that results in 90%
inhibition of viral replication in vitro. EDP-235 200 mg taken once daily with food resulted in mean trough plasma levels
at steady state that were 3-fold and 7-fold over the plasma-protein-adjusted EC90 for the tested Alpha variant and Omicron
variant, respectively, while 400 mg resulted in levels that were 6-fold and 13-fold over the plasma-protein-adjusted EC90
for the respective variants. These target exposure multiples were achieved without the need for ritonavir boosting and its
associated drug-drug interactions.

Phase 2 Study: In May 2023, we reported topline results from SPRINT (SARS-CoV-2 Protease Inhibitor Treatment), a
Phase 2 clinical trial of EDP-235. This randomized, double-blind, placebo-controlled study evaluated the safety,
tolerability, antiviral activity and clinical symptoms of EDP-235 compared to placebo in approximately 230 non-
hospitalized, symptomatic patients with mild to moderate COVID-19 who were not at increased risk for developing severe
disease. Patients were eligible to participate if they had symptoms for five days or less and had not received a SARS-CoV-
2 vaccine or been infected with SARS-CoV-2 within 90 days of enrollment. Patients received either 200 mg or 400 mg or
EDP-235 or placebo orally with food once daily for five days. EDP-235 met the primary endpoint of the trial and was
generally safe and well-tolerated. A dose-dependent improvement in total symptom score was observed with EDP-235
treatment compared to placebo, which achieved statistical significance (p<0.05) in the 400 mg treatment group at multiple
time points, starting as early as one day after the first dose. In a prespecified population consisting of patients enrolled
within three days of symptom onset, a statistically significant improvement was observed with EDP-235 at 400 mg at all
time points. While no difference was observed in time to improvement of 14 targeted COVID-19 symptoms, an analysis
of a subset of six symptoms showed a two-day shorter time to improvement in patients receiving EDP-235 400 mg who
were enrolled within three days of symptom onset (p<0.01). No effect on virologic endpoints as measured in the nose was
detected due to the rapid viral decline in the placebo arm of this highly immunologically-experienced, standard risk
population. However, in the subset of patients who were nucleocapsid seronegative (indicating no recent natural infection
with SARS-CoV-2), a viral load decline was observed at day five in the 400 mg group of 0.8 log overall and 1 log in the
patients with symptom onset within three days before treatment with EDP-235. An additional analysis of patients with a
baseline viral load greater than 5 logs showed a decline of 0.4 log at day three in both EDP-235 treatment arms compared
to placebo.

•

Next Steps: Going forward, we will continue to focus on potential partnerships or collaborations to progress EDP-235 as
we will not advance EDP-235 on our own without a commercial partner.

Our HBV Program

Background and Overview of HBV

Hepatitis B virus, or HBV, is a potentially life-threatening liver infection. It is estimated that close to 300 million people worldwide
are chronically infected, and 15-40% of patients with chronic HBV infection develop chronic liver disease, including cirrhosis, liver
cancer, or liver decompensation. HBV is a leading cause of chronic liver disease and liver transplantation.

Current approaches to treatment include interferon therapy and/or inhibitors of HBV nucleoside reverse transcriptase, which suppress
the virus but require lifelong therapy and rarely result in full eradication of the virus from the liver. Treatment with interferon offers

modest cure rates, and is accompanied by serious side effects, including flu-like symptoms, fatigue, headache and nausea. New
treatments that can provide functional cures to chronically-infected patients are urgently needed.

Scientific Background

HBV is a partially double-stranded DNA virus with a complex life cycle. There are multiple mechanisms associated with HBV
replication that could potentially be targeted with new drugs. Mechanisms under study for HBV include entry inhibitors, core
inhibitors or capsid assembly modulators (CAMs), siRNA/ASO targeting the HBV S antigen, and immune modulators (eg; TLRs, PD-
L1s, therapeutic vaccines, etc). These new HBV mechanisms are being studied with nucleoside inhibitors and in combination with
each other, with the goal of achieving a functional cure for a significant number of HBV patients.

We believe that HBV, like HIV and HCV, will be optimally treated with multiple agents that have different mechanisms, and
therefore seek to develop a combination regimen. We initially focused on inhibitors of the HBV core protein, as it plays a critical role
in viral replication, intracellular trafficking, and maintenance of chronic infections. Core inhibitors are replication inhibitors that have
been shown to act at multiple steps in the HBV lifecycle; preventing proper uncoating, nuclear import, assembly, and recycling as well
as potentially impacting other viral processes. This approach is supported by clinical validation, demonstrating reduction of viral RNA
and DNA in chronic HBV patients in Phase 2 clinical studies.

Competitive Landscape

Many companies are seeking to develop new HBV drugs, with a goal to identify a combination of mechanisms for a treatment
regimen including Vir, GSK, Arbutus, and Roche who have multiple combination regimens under investigation in later stage clinical
studies. In addition, several companies have Phase 1 or earlier stage HBV programs.

EDP-514

EDP-514, our most advanced novel core inhibitor, displays potent anti-HBV activity in vitro at multiple points in the HBV lifecycle
and has been studied in two Phase 1b studies in patients with chronic HBV.

•

In the first study, which evaluated EDP-514 in NUC-suppressed chronic HBV patients, EDP-514 was generally safe and
well-tolerated at 200, 400 and 800 mg doses for 28 days and exhibited pharmacokinetics suitable for once daily oral
dosing. EDP-514 led to a maximum HBV RNA reduction of 2.3 log in HBeAg-negative and 2.8 log in HBeAg-positive
subjects in the EDP-514 arms compared to 1.2 log in placebo.

A separate Phase 1b study was conducted in patients with chronic HBV infection who were not previously on HBV
therapy and had high levels of virus in their blood, whom we refer to as viremic HBV patients. Results demonstrated that
EDP-514 was safe and well-tolerated through 28 days of treatment, and displayed pharmacokinetics supportive of once-
daily dosing. Mean HBV DNA reductions of 2.9, 3.3, and 3.5 logs were observed at 28 days for the 200 mg, 400 mg, and
800 mg cohorts, respectively, compared to 0.2 log in the placebo cohort. Mean HBV RNA reductions in the three viremic
treatment cohorts were at least 2 logs compared to a 0.02 log reduction in the placebo group.

Our goal is to develop a combination therapy approach, including existing approved treatments such as a NUC, with EDP-514 and one
or more other mechanisms, which could lead to a functional cure for patients with chronic HBV infection. Opportunities for internal or
external development of this approach are dependent upon our finding a new mechanism of action to use in such a combination.

Our Out-Licensed HCV Protease Inhibitor Products

Background and Overview of HCV Market

HCV is a virus that is a common cause of viral hepatitis, an inflammation of the liver. HCV is typically contracted by contact with the
blood or other body fluids of another individual infected with HCV. HCV is a leading cause of chronic liver disease, including
cirrhosis, liver failure and cancer, and the leading cause of death from liver disease in the United States. HCV disease progression
occurs over a period of 20 to 30 years, with the majority of HCV-infected individuals generally exhibiting no major symptoms in the
early stages of the disease. Therefore, until a major symptom is diagnosed, many individuals are unaware they are infected and live
undiagnosed without seeking treatment. For that reason, combined with the new availability of effective treatments for HCV, the
United States Centers for Disease Control and Prevention, or CDC, issued new guidelines in 2013 recommending screening for all
Americans born between the years 1945 and 1965 so that HCV-infected individuals will be aware of their condition and can consider
treatment options.

An estimated 58 million people worldwide are chronically infected with HCV and have an increased risk of eventually developing
liver cirrhosis or liver cancer. Approximately 290,000 people die every year from HCV-related liver diseases. According to the CDC,
the incidence rate of acute HCV has increased 15% since 2019, with an estimated 66,700 new infections in 2020, the most recent year
for which the CDC has published data. During 2020, 41 states reported a total of 107,300 newly identified chronic HCV cases in 2020,
corresponding to 40.7 chronic HCV cases per 100,000. HCV-associated deaths during 2020 increased 4% (3.45 deaths per 100,000

people), compared to 2019 (3.33 deaths per 100,000 people). We believe that the chronically infected population remains significantly
untreated, even with the introduction of several new treatment regimens beginning in 2013.

The approved treatments for HCV have provided significant benefit to HCV patients. To date, these treatments have cure rates
approaching 100% in several subpopulations. Medical practice defines a “cure” as the point at which there is no quantifiable virus in a
patient’s blood for a sustained period of time after cessation of therapy, which is often referred to as a sustained virologic response, or
SVR. For AbbVie’s MAVYRET/MAVIRET regimen, the majority of chronic HCV patients only require 8 weeks of treatment
compared to 12 weeks with other HCV regimens, including Gilead’s EPCLUSA® and HARVONI® in almost all HCV genotypes.

Since the introduction of Gilead’s Harvoni® and AbbVie’s VIEKIRA PAK® in late 2014, the reported worldwide sales of the leading
HCV therapies have declined from $23 billion in 2015 to $3.4 billion in 2022. Through the first nine months of calendar 2023,
reported worldwide net sales were $2.5 billion. HCV sales have declined since their peak in 2015 due to payers obtaining additional
discounts, competitive market dynamics and a decline in the number of patients treated annually after the initial wave of diagnosed
chronic HCV patients who had urgency for treatment. Despite the high numbers of HCV patients that have been successfully treated,
there remains a large population of chronic HCV-infected patients who have yet to be treated with one of the newer “high cure”
regimens. In addition, and as noted above, new HCV infections (principally in association with IV drug use) are an ongoing target
population for treatment.

COVID-19 has also impacted new HCV patient volumes, HCV diagnoses, HCV prescriptions and sales of MAVYRET/MAVIRET
worldwide. While new HCV infections are continuing, at this time it is uncertain when and the extent to which treatment of new HCV
patients and revenues will return to pre-COVID-19 levels.

Our Out-Licensed Products in AbbVie’s Marketed Therapies

Glecaprevir - Our protease inhibitor, glecaprevir, which is part of the latest HCV regimen from AbbVie, was developed by AbbVie in
combination with pibrentasvir, AbbVie’s second NS5A inhibitor. This co-formulated combination, marketed under the tradenames
MAVYRET® (U.S.) and MAVIRET® (ex-U.S.), contains two novel DAAs that target and inhibit proteins essential for the replication
of HCV. MAVYRET/MAVIRET is approved in the U.S., EU, Japan and numerous other countries globally as an 8-week, pan-
genotypic, fixed-dose combination treatment, dosed once-daily as three oral tablets, taken with food, for chronic HCV patients without
cirrhosis and new to treatment. MAVYRET/MAVIRET is also approved as a treatment for patients with specific treatment challenges,
including those GT-1 patients not cured by prior treatment experience with either a protease inhibitor or an NS5A inhibitor (but not
both), and in patients with limited treatment options, such as those with severe chronic kidney disease, or CKD, or those with
genotype 3 chronic HCV. MAVYRET/MAVIRET is approved for use in patients across all stages of CKD with any of the major HCV
genotypes (GT1-6). The approvals of MAVYRET/MAVIRET are supported by data from nine registrational studies in AbbVie’s
clinical development program, which evaluated more than 2,300 patients in 27 countries across all major HCV genotypes (GT1-6) and
special populations:

•

8 weeks for treatment-naïve, non-cirrhotic patients: In November 2016, results from several Phase 3 studies of this
combination demonstrated 97.5% of chronic HCV infected patients without cirrhosis and new to treatment across all
major genotypes (GT1-6) achieved sustained virologic response at 12 weeks post-treatment, referred to as SVR12, with
just 8 weeks of MAVYRET/MAVIRET treatment.

8 weeks for GT-3: Data from AbbVie’s ENDURANCE-3 study were presented at the 2017 ILC, demonstrating that 95%
of patients with challenging-to-treat, genotype 3, or GT3, chronic HCV infection, without cirrhosis and new to treatment,
achieved SVR12 after 8 weeks of treatment with MAVYRET/MAVIRET.

8 weeks for compensated cirrhosis: Based on data from AbbVie’s EXPEDITION-8 study, which demonstrated that with
8 weeks of MAVYRET treatment, 100 percent (n=273/273) of genotype 1, 2, 4, 5 and 6 patients achieved a sustained
virologic response 8 weeks after treatment (SVR8) per protocol analysis. Based on this data and a second cohort of the
study in GT3 chronic HCV-infected patients, MAVYRET is now approved for all genotypes with compensated cirrhosis
in the U.S.

12 weeks with chronic kidney disease: Results were also presented from AbbVie’s EXPEDITION-4 study in chronic
HCV patients with chronic kidney disease, or CKD, in which 98% of patients (n=102/104) across all major genotypes
(GT1-6) achieved SVR12 with 12 weeks of treatment with MAVYRET/MAVIRET.

Paritaprevir - The first protease inhibitor developed through our collaboration with AbbVie, paritaprevir, is part of AbbVie’s 3-DAA
regimen approved for the treatment of genotype 1 and 4 HCV patients. This 3-DAA combination was sold as VIEKIRA PAK®
(paritaprevir/ritonavir/ombitasvir/dasabuvir) in the U.S. from December 2014 to December 2018, and as VIEKIRAX®+EXVIERA® in
most other jurisdictions, for non-cirrhotic patients and those with early stage, or compensated, cirrhosis. These regimens have been
almost entirely replaced by MAVYRET/MAVIRET.

Collaboration and License Agreement with AbbVie

We entered into a Collaborative Development and License Agreement with Abbott Laboratories in November 2006 to develop and
commercialize HCV NS3 and NS3/4A protease inhibitors. The agreement, which was amended in January and December 2009, was
then assigned to AbbVie Inc. on January 1, 2013 in connection with Abbott’s transfer of its research-based pharmaceuticals business
to AbbVie. Under the agreement, we have granted AbbVie an exclusive, worldwide, royalty-bearing license, including a right to grant
sublicenses, to specified intellectual property, including several issued U.S. patents, relating to protease inhibitors. We also granted
AbbVie access to our drug discovery capabilities in the HCV NS3 and NS3/4A protease inhibitor field. AbbVie granted us a co-
exclusive (together with AbbVie), royalty-free, fully paid license, without the right to grant sublicenses, to certain of AbbVie’s
intellectual property, AbbVie’s interest in joint intellectual property and improvements discovered by AbbVie, for the purpose of
allowing us to conduct certain development and commercialization activities in the United States relating to protease inhibitors.
AbbVie is responsible for and has funded all costs associated with the development, manufacturing and commercialization of
paritaprevir, glecaprevir and any other compounds under this agreement. Under the agreement, we are eligible to receive milestone
payments and royalties with respect to these compounds. So long as a product candidate is being developed or commercialized under
the agreement, we undertake not to conduct any activity, or grant licenses to a third party, relating to protease inhibitors.

A joint steering committee was established under the agreement with review and oversight responsibilities for all research,
development and commercialization activities. The joint steering committee is comprised of three of our senior personnel and three
senior personnel from AbbVie; however, AbbVie has final authority to make all decisions regarding development and
commercialization activities.

The research program and the evaluation period, which was performed by both parties, ended in June 2011. The first commercialized
compound was paritaprevir with the second commercialized compound, glecaprevir, approved in 2017 and marketed under the
tradenames MAVYRET® (U.S.) or MAVIRET™ (ex-U.S.). Under this collaboration we have received $396 million in payments from
AbbVie for license payments, proceeds from a sale of preferred stock, research funding payments and milestone payments.

We also receive annually tiered, double-digit royalties per protease inhibitor product developed under the agreement, which range
from ten percent up to twenty percent, or on a blended basis from the low double digits up to the high teens. However, if a product is
determined to be a combination product, as is the case for both glecaprevir and paritaprevir, the net sales of the combination product
are adjusted on a country-by-country and product-by-product basis to reflect a good faith determination of the relative value of each
pharmaceutically active ingredient, based on the estimated fair market value. This means that a portion of AbbVie’s worldwide annual
net sales of a combination product or regimen is first allocated to one of our protease inhibitors and then that royalty-bearing portion is
multiplied by the annually tiered royalty rates to determine our actual royalty for the protease product in that regimen in a given
period. Under the terms of our agreement, as amended in October 2014, 50% of AbbVie’s net sales of MAVYRET/MAVIRET are
allocated to glecaprevir. Beginning with each January 1, the cumulative net sales of a given royalty-bearing protease inhibitor product
start at zero for purposes of calculating the tiered royalties on a product-by-product basis. Under this collaboration, we have received
royalty payments from AbbVie totaling $891 million through September 30, 2023. Further details of these tiered royalties are set
forth in Note 7 in Notes to Consolidated Financial Statements included in this report, which are incorporated herein by this reference.

Royalties owed to us under the agreement can be reduced by AbbVie in certain circumstances, including (i) if AbbVie exercises its
right to license or otherwise acquire rights to intellectual property controlled by a third party where a product could not be legally
developed or commercialized in a country without the third-party intellectual property right, (ii) where a product developed under the
collaboration agreement is sold in a country and not covered by a valid patent claim in such country, or (iii) where sales of a generic
product are equal to at least a specified percentage of AbbVie’s market share of a product in a country.

AbbVie’s obligation to pay royalties on products developed under the agreement expires on a country-by-country and product-by-
product basis upon the later of (i) the date of expiration of the last of the licensed patents with a valid claim covering the product in the
applicable country, and (ii) ten years after the first commercial sale of the product in the applicable country.

Our intellectual property existing as of the effective date of the agreement remains our property. Any intellectual property jointly
developed is jointly owned. We will have the unilateral right to enforce our patent rights on any covered product following the first
commercial sale of such product, as will AbbVie. In the event of infringement related to any of our patents, we will have the first right
and option to initiate legal proceedings or take other actions. In the event of infringement related to any AbbVie patents, AbbVie will
have the first right and option to initiate legal proceedings or take other actions. In the event of infringement of a joint patent right, we
will discuss with AbbVie whether to initiate legal proceedings or take other actions. AbbVie will have the obligation to defend at its
sole expense any actions brought against either party alleging infringement of third-party rights by reason of the activities conducted
under the agreement and we will have the right to obtain separate counsel at our own expense. Additionally, AbbVie, at its sole
expense, will be responsible for all trademark prosecution.

Subject to the exceptions described above, a party’s rights and obligations under the agreement continue until: (i) such time as AbbVie
is no longer developing a product candidate or (ii) if, as of the time AbbVie is no longer developing any product candidates, AbbVie is
commercializing any other protease inhibitor product, such time as all royalty terms for all covered products and all co-development
terms for all co-developed products have ended. Accordingly, the final expiration date of the agreement is currently indeterminable.

Either party may terminate the agreement for cause in the event of a material breach, subject to prior notice and the opportunity to
cure, or in the event of the other party’s bankruptcy. Additionally, AbbVie may terminate the agreement for any reason upon specified
prior notice.

If we terminate the agreement for cause or AbbVie terminates without cause, any licenses and other rights granted to AbbVie will
terminate and AbbVie will be deemed to have granted us (i) a non-exclusive, perpetual, fully paid, worldwide, royalty-free license,
with the right to sublicense, under AbbVie’s intellectual property used in any product candidate and (ii) an exclusive (even as to
AbbVie), perpetual, fully paid, worldwide, royalty-free license, with the right to sublicense, under AbbVie’s interest in joint
intellectual property rights to develop product candidates resulting from covered compounds and to commercialize any products
derived from such compounds. Upon our request, AbbVie will also transfer to us all right, title and interest in any related product
trademarks, regulatory filings and clinical trials.

If AbbVie terminates the agreement for our uncured breach, the royalty payments payable by AbbVie may be reduced, the licenses
granted to AbbVie will remain in place, we will be deemed to have granted AbbVie an exclusive license under our interest in joint
intellectual property, AbbVie will continue to have the right to commercialize any covered products, and all rights and licenses
granted to us by AbbVie will terminate.

Royalty Sale Agreement

In April 2023, we entered into a royalty sale agreement with an affiliate of OMERS, a Canadian public employee pension fund,
pursuant to which we were paid a $200.0 million cash purchase price in exchange for 54.5% of our future quarterly royalty payments
on net sales of MAVYRET/MAVIRET, after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments to
OMERS equal to 1.42 times the purchase price.

For accounting purposes, we will continue to record 100% of HCV royalties earned under the AbbVie agreement as royalty revenue in
our consolidated statements of operation. The $200.0 million received in April 2023 was recognized on our consolidated balance
sheets as a liability which will be reduced by the payments made to OMERS over the term of the Agreement. We will recognize
imputed interest expense over the life of the royalty sale agreement based on our estimated future MAVYRET/MAVIRET royalties.

Drug Discovery

We have internally discovered all of the compounds in our research and development programs. Our scientists have expertise in the
areas of medicinal chemistry, molecular virology, pharmacology, and toxicology with highly developed sets of skills in compound
generation, target selection, screening and pharmacology, preclinical development and lead optimization. We are utilizing these skills
and capabilities in our discovery and development of virology and liver disease product candidates.

We focus on virology and other disease indications representing large and growing market opportunities with significant unmet
medical needs. Our selection of a particular therapeutic target within those disease indications takes into consideration the experience
and expertise of our scientific team and includes our ability to generate robust medicinal chemistry structure-activity relationships to
assist lead optimization and secure relevant intellectual property rights. Once we have identified lead compounds, they are tested using
in vitro and in vivo pharmacology studies and in vivo research models of antiviral or antibacterial efficacy.

Business Development

We also regularly examine opportunities to in-license compounds and technologies to complement our existing internal discovery
programs. In addition, we engage from time to time in discussions with third parties to out-license intellectual property that no longer
fits in our strategic priorities for our internal research and development programs. For example, in December 2022 we out-licensed
one of our antibiotic compounds in exchange for a $1.0 million up-front fee and future milestone payments and royalties.

Competition

We are engaged in segments of the pharmaceutical industry that are highly competitive and rapidly changing. Many large
pharmaceutical and biotechnology companies, academic institutions, governmental agencies and other public and private research
organizations are commercializing or pursuing the development of products that target HCV, RSV, SARS-CoV-2, HBV and other
indications that we may target now or in the future.

Many of our competitors have substantially greater commercial infrastructures and financial, technical and personnel resources than
we have, as well as drug candidates in late-stage clinical development. We will not be able to compete successfully unless we are able
to:

•

design and develop products that are superior to other products in the market;

attract qualified scientific, medical, regulatory, sales and marketing and commercial personnel;

obtain patent and/or other proprietary protection for our processes and product candidates;

•

obtain required regulatory approvals; or

collaborate with others in the development and commercialization of new products.

Established competitors may invest heavily to quickly discover and develop novel compounds that could make our product candidates
obsolete. In addition, any new product that competes with an approved product must demonstrate compelling advantages in efficacy,
convenience, tolerability and safety, or some combination of these factors, to overcome competition and to be commercially
successful.

RSV, COVID-19 and HBV represent competitive therapeutic areas. For RSV, there are currently no safe and effective treatments.
Several companies are seeking to develop new antiviral treatments for RSV infection in adult and pediatric patients. Ark Biosciences
and Pfizer/ReViral (acquired in June 2022) have fusion inhibitors in later stage clinical development. Synagis, a prophylactic,
monoclonal-antibody-based treatment from AstraZeneca, which is commercialized by AbbVie outside the U.S., is approved for
infants considered at high risk for RSV infection; however, studies have found that most young children with RSV infection were
previously healthy, and thus would not normally be prescribed prophylactic treatment. A newer monoclonal antibody, nirsevimab, was
recently approved in the U.S./EU for newborns and infants in their first RSV season and children at high-risk up to 24 months of age.
Additionally, a maternal vaccine was also approved. Furthermore, two vaccines have been approved for adults older than 60 years of
age.

For SARS-CoV-2, there is one approval (Paxlovid, a 3CL protease inhibitor) and two Emergency Use Authorizations (Molnupiravir, a
polymerase inhibitor, and Paxlovid) for oral antiviral treatments for non-hospitalized, high-risk patients with SARS-CoV-2 infection.
Additionally, there are companies developing oral direct acting antivirals for SARS-CoV-2 that are currently in global Phase 3 studies
including Shionogi, Atea, and Gilead as well as additional compounds in Phase 1 or 2 studies.

We expect AbbVie’s MAVYRET/MAVIRET to continue to face intense competition due to existing approved products in the HCV
market. AbbVie’s MAVYRET/MAVIRET regimen currently faces competition in various world markets and subpopulations of HCV
from Gilead’s Epclusa® (a fixed dose combination of sofosbuvir and velpatasvir), Vosevi® (a triple combination therapy of
sofosbuvir, velpatasvir and voxilaprevir approved by the FDA for specified sofosbuvir -treatment failures and NS5A-inhibitor
treatment failures) and Harvoni® (a fixed-dose combination of sofosbuvir and ledipasvir); and to a lesser extent - Merck’s Zepatier®
(a fixed-dose combination of grazoprevir and elbasvir). Gilead launched authorized generic versions of Epclusa and Harvoni through
its subsidiary, Asegua Therapeutics, LLC, which have had an impact on the competitive landscape. For example, the state of
Louisiana selected Asegua as their HCV subscription model pharmaceutical partner to provide the state with unrestricted access to its
direct-acting antiviral medication.

Other competitive products in the form of other treatment methods or a vaccine for HCV may render MAVYRET/MAVIRET obsolete
or noncompetitive. MAVYRET/MAVIRET will face competition based on its safety and effectiveness, reimbursement coverage,
price, patent position, AbbVie’s marketing and sales capabilities, and other factors. If MAVYRET/MAVIRET faces competition from
generic products other than authorized generic versions by the manufacturer of the branded product (i.e. Gilead and Asegua
Therapeutics), our collaboration agreement provides that the royalty rate applicable to our protease product contained in the regimen is
reduced significantly by a specified percentage on a product-by-product, country-by-country basis. If AbbVie is not able to compete
effectively against its competitors in HCV, our business will not grow and our financial condition, operations and stock price will
suffer.

If we are not able to develop new products that can compete effectively against our current and future competitors, our business will
not grow and our financial condition, operations and stock price will suffer.

Intellectual Property

As part of our business strategy, we actively seek patent protection for our product candidates in the United States and certain major
foreign jurisdictions and file additional patent applications, when appropriate, to cover improvements to our compounds. We also rely
on trade secrets, internal know-how, technological innovations and agreements with third parties to develop, maintain and protect our
competitive position. Our ability to be competitive will depend on the success of this strategy.

Each of our major research and development programs, including RSV, SARS-CoV-2 as well as HBV and our out-licensed products
for HCV and our FXR agonist assets, typically has several pending patent claims and issued patents in the program area containing
claims to compounds, methods of use and processes for synthesis. However, only a few of the issued patents and/or pending patent
applications cover the lead product candidate in a given program.

RSV, SARS-CoV-2, HBV. Our patent portfolio directed to N-and L-protein inhibitors for RSV, protease inhibitors for SARS-CoV-2
and core inhibitors for HBV, includes issued U.S. patents or pending U.S. patent applications, or both, as well as numerous foreign

patent applications. We expect that our existing patents and patent applications (assuming patents are ultimately issued), will provide
patent coverage in the U.S., if and when a compound is approved by the FDA, until at least 2038 for each of our compounds currently
in clinical development.

HCV NS3 Protease Inhibitor Program. The patent portfolio directed to the HCV protease inhibitor program with AbbVie includes
U.S. patents and foreign patents, as well as non-provisional applications. The issued U.S. composition-of-matter patent covering
paritaprevir is expected to expire in 2031. The issued U.S. composition-of-matter patent covering glecaprevir is expected to expire in
2032. AbbVie is a joint owner of a number of the non-provisional patent applications. AbbVie also has rights to some or all of these
patents and patent applications pursuant to its collaboration agreement with us.

We may obtain patents for certain compounds many years before we obtain marketing approval for products containing such
compounds. Because patents have a limited life, which usually begins to run well before the first commercial sale of the related
product, the commercial value of the patent may be limited. However, we may be able to apply for patent term extensions in the
United States and in a number of European countries, compensating in part for delays in obtaining marketing approval, but we cannot
be certain we will obtain such extensions.

It is also very important that we do not infringe patents or other proprietary rights of others. If we do infringe such patents or other
proprietary rights, we could be prevented from developing or selling products or from using the processes covered by those patents,
could be required to pay substantial damages, or could be required to obtain a license from the third party to allow us to use their
technology, which may not be available on commercially reasonable terms or at all. If we were not able to obtain a required license or
develop alternative technologies, we may be unable to develop or commercialize some or all of our products, and our business could
be adversely affected.

In addition, we jointly own patent applications, together with AbbVie, that claim paritaprevir and glecaprevir as a chemical entity.
However, there is no guarantee that such applications will issue. Further, the existence of issued patents does not guarantee our right to
practice the patented technology or commercialize the patented product. Third parties may have already or could obtain rights to
patents that could be used to prevent or attempt to prevent us from commercializing our product candidates. If these other parties are
successful in obtaining valid and enforceable patents, and establishing our infringement of those patents, we could be prevented from
commercializing our product candidates unless we were able to obtain a license under such patents, which may not be available on
commercially reasonable terms or at all.

Much of our scientific capabilities depend upon the knowledge, experience and skills of key scientific and technical personnel. To
protect our rights to our proprietary know-how and technology, we endeavor to require all employees, as well as our consultants and
advisors, when feasible, to enter into confidentiality agreements that require disclosure and assignment to us of ideas, developments,
discoveries and inventions made by these employees, consultants and advisors in the course of their service to us.

We may be unable to obtain, maintain and protect the intellectual property rights necessary to conduct our business, and we may be
subject to claims that we infringe or otherwise violate the intellectual property rights of others, which could materially harm our
business. For more information, see “Risk Factors—Risks Related to Our Intellectual Property Rights.”

Government Regulation

Government authorities in the United States, at the federal, state and local level, and in other countries extensively regulate, among
other things, the research, development, testing, manufacture, quality control, approval, labeling, packaging, storage, record-keeping,
promotion, advertising, distribution, post-approval monitoring and reporting, marketing and export and import of products such as
those we develop. Any pharmaceutical candidate that we develop must be approved by the FDA before it may be legally marketed in
the United States and by the appropriate foreign regulatory agency before it may be legally marketed in foreign countries.

United States Drug Development Process

In the United States, the FDA regulates drugs under the Federal Food, Drug and Cosmetic Act, or FDCA, and implementing
regulations. Drugs are also subject to other federal, state and local statutes and regulations. The process of obtaining regulatory
approvals and the subsequent compliance with appropriate federal, state, local and foreign statutes and regulations require the
expenditure of substantial time and financial resources. Failure to comply with the applicable United States requirements at any time
during the product development process, approval process or after approval, may subject an applicant to administrative or judicial
sanctions. FDA and other governmental sanctions could include refusal to approve pending applications, withdrawal of an approval, a
clinical hold, enforcement letters, product recalls, product seizures, total or partial suspension of production or distribution,
injunctions, fines, refusals of government contracts, restitution, disgorgement or civil or criminal penalties. Any agency or judicial
enforcement action could have a material adverse effect on us.

The process required by the FDA before a drug may be marketed in the United States generally involves the following:

•

Completion of preclinical laboratory tests, animal studies and formulation studies according to Good Laboratory Practice,
or GLPs, or other applicable regulations;

Submission to the FDA of an Investigational New Drug Application, or an IND, which must become effective before
human clinical trials may begin;

Performance of adequate and well-controlled human clinical trials according to the FDA’s current Good Clinical Practice,
or GCPs, to establish the safety and efficacy of the proposed drug for its intended use;

Submission to the FDA of a New Drug Application, or an NDA, for a new drug product;

Satisfactory completion of an FDA inspection of the manufacturing facility or facilities where the drug is to be produced
to assess compliance with the FDA’s current Good Manufacturing Practice standards, or cGMP, to assure that the
facilities, methods and controls are adequate to preserve the drug’s identity, strength, quality and purity;

Potential FDA audit of the nonclinical and clinical trial sites that generated the data in support of the NDA; and

FDA review and approval of the NDA.

The lengthy process of seeking required approvals, which can often take anywhere from six months from the time the NDA is filed if
there is a priority review for a breakthrough therapy to at least ten months for a standard review, and the continuing need for
compliance with applicable statutes and regulations, require the expenditure of substantial resources. There can be no certainty that
approvals will be granted.

Before testing any compounds with potential therapeutic value in humans, the product candidate enters the preclinical testing stage.
Preclinical tests include laboratory evaluations of product chemistry, toxicity and formulation, as well as animal studies to assess the
potential safety and activity of the product candidate. The conduct of the preclinical tests must comply with GLP and other federal
regulations and requirements. The sponsor must submit the results of the preclinical tests, together with manufacturing information,
analytical data, any available clinical data or literature and a proposed clinical protocol, to the FDA as part of the IND. The IND
automatically becomes effective 30 days after receipt by the FDA, unless the FDA places the clinical trial on a clinical hold within
that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial
can begin. The FDA may also impose clinical holds on a drug at any time before or during clinical trials due to safety concerns or non-
compliance. Accordingly, we cannot assure that submission of an IND will result in the FDA allowing clinical trials to begin, or that,
once begun, issues will not arise that result in suspension or termination of such trial.

Clinical trials involve the administration of the product candidate to healthy volunteers or patients having the disease being studied
under the supervision of qualified investigators, generally physicians not employed by or under the trial sponsor’s control. Clinical
trials are conducted under protocols detailing, among other things, the objectives of the clinical trial, dosing procedures, subject
selection and exclusion criteria, and the parameters to be used to monitor subject safety. Each protocol must be submitted to the FDA
as part of the IND. Clinical trials must be conducted in accordance with the FDA’s GCP requirements. Further, each clinical trial must
be reviewed and approved by an independent institutional review board, or IRB, at or servicing each institution at which the clinical
trial will be conducted. An IRB is charged with protecting the welfare and rights of trial participants and considers such items as
whether the risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits.
The IRB also approves the informed consent form that must be provided to each clinical trial subject or his or her legal representative
and must monitor the clinical trial until it is completed.

Human clinical trials prior to approval are typically conducted in three sequential phases that may overlap or be combined:

•

Phase 1. The drug is initially introduced into healthy humans and tested for safety, dosage tolerance, absorption,
metabolism, distribution and excretion. In the case of some products for severe or life-threatening diseases, especially
when the product may be too inherently toxic to ethically administer to healthy volunteers, the initial human testing is
often conducted only in patients having the specific disease.

Phase 2. The drug is evaluated in a limited patient population to identify possible adverse effects and safety risks, to
preliminarily evaluate the efficacy of the product for specific targeted diseases and to determine dosage tolerance, optimal
dosage and dosing schedule for patients having the specific disease.

Phase 3. Clinical trials are undertaken to further evaluate dosage, clinical efficacy and safety in an expanded patient
population at geographically dispersed clinical trial sites. These clinical trials, which usually involve more patients than
earlier trials, are intended to establish the overall risk/benefit ratio of the product and provide an adequate basis for
product labeling. Generally, at least two adequate and well-controlled Phase 3 clinical trials are required by the FDA for
approval of an NDA.

Post-approval studies, or Phase 4 clinical trials, may be conducted after initial marketing approval. These studies are used to gain
additional experience from the treatment of patients in the intended therapeutic indication and may be required by the FDA as part of
the approval process.

Progress reports detailing the results of the clinical trials must be submitted at least annually to the FDA and written IND safety
reports must be submitted to the FDA by the investigators for serious and unexpected adverse events or any finding from tests in
laboratory animals that suggests a significant risk for human patients. Phase 1, Phase 2 and Phase 3 clinical trials may not be
completed successfully within any specified period, if at all. The FDA, or the sponsor or its data safety monitoring board, may
suspend a clinical trial at any time on various grounds, including a finding that the research patients are being exposed to an
unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution if the clinical trial is
not being conducted in accordance with the IRB’s requirements or if the drug has been associated with unexpected serious harm to
patients.

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

U.S. Review and Approval Processes

The results of product development, preclinical studies and clinical trials, along with descriptions of the manufacturing process,
analytical tests conducted on the chemistry of the drug, proposed labeling and other relevant information are submitted to the FDA as
part of an NDA requesting approval to market the product. The submission of an NDA is subject to the payment of substantial user
fees by the applicant; a waiver of such fees may be obtained under certain limited circumstances.

In addition, under the Pediatric Research Equity Act, or PREA, an NDA or supplement to an NDA must contain data to assess the
safety and effectiveness of the drug for the claimed indications in all relevant pediatric subpopulations and to support dosing and
administration for each pediatric subpopulation for which the product is safe and effective. The FDA may grant deferrals for
submission of pediatric data or full or partial waivers.

The FDA reviews all NDAs submitted before it accepts them for filing and may request additional information rather than accepting
an NDA for filing. Once the submission is accepted for filing, the FDA begins an in-depth review of the NDA. Under the goals and
policies agreed to by the FDA under the Prescription Drug User Fee Act, or PDUFA, the FDA has ten months in which to complete its
initial review of a standard NDA and respond to the applicant, and six months for a priority NDA. The review clock for an NDA may
be extended if a major amendment is submitted during the review cycle. In addition, the FDA does not always meet its PDUFA goal
dates for standard and priority NDAs.

After the NDA submission is accepted for filing, the FDA reviews the NDA to determine, among other things, whether the proposed
product is safe and effective for its intended use and whether the product is being manufactured in accordance with cGMP to assure
and preserve the product’s identity, strength, quality and purity. In addition to its own review, the FDA may refer applications for
novel drug products or drug products that present difficult questions of safety or efficacy to an advisory committee, typically a panel
that includes clinicians and other experts, for review, evaluation and a recommendation as to whether the application should be
approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such
recommendations carefully when making decisions. During the approval process, the FDA also will determine whether a Risk
Evaluation and Mitigation Strategy, or REMS, is necessary to assure the safe use of the drug. If the FDA concludes that a REMS is
needed, the sponsor of the NDA must submit a proposed REMS; the FDA will not approve the NDA without a REMS, if required.

Before approving an NDA, the FDA will inspect the facilities at which the product is to be manufactured. The FDA will not approve
the product unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and are
adequate to assure consistent production of the product within required specifications. Additionally, before approving an NDA, the
FDA will typically inspect one or more clinical sites to assure compliance with GCP. If the FDA determines that the application,
manufacturing process or manufacturing facilities are not acceptable, it will outline the deficiencies in the submission and often will
request additional testing or information.

The NDA review and approval process is lengthy and difficult, and the FDA may refuse to approve an NDA if the applicable
regulatory criteria are not satisfied or may require additional clinical data or other data and information. Even if such data and
information is submitted, the FDA may ultimately decide that the NDA does not satisfy the criteria for approval. Data obtained from
clinical trials are not always conclusive and may be susceptible to varying interpretations, which could delay, limit or prevent
regulatory approval. The FDA will issue a “complete response” letter if the agency decides not to approve the NDA. The complete
response letter usually describes all of the specific deficiencies in the NDA identified by the FDA. The deficiencies identified may be
minor, for example, requiring labeling changes, or major, for example, requiring additional clinical trials. Additionally, the complete

response letter may include recommended actions that the applicant might take to place the application in a condition for approval. If a
complete response letter is issued, the applicant may either resubmit the NDA, addressing all of the deficiencies identified in the letter,
or withdraw the application.

If a product receives regulatory approval, the approval may be limited to specific diseases and dosages or the indications for use may
otherwise be limited, which could restrict the commercial value of the product. Further, the FDA may require that certain
contraindications, warnings or precautions be included in the product labeling. In addition, the FDA may require Phase 4 testing,
which involves clinical trials designed to further assess a product’s safety and effectiveness and may require testing and surveillance
programs to monitor the safety of approved products that have been commercialized.

Expedited Development and Review Programs

The FDA has four programs intended to expedite the development and review of new drugs addressing unmet medical needs or
treating serious or life-threatening conditions: fast track, breakthrough therapy, priority review, and accelerated approval, in addition
to emergency use authorization, or EUA, in situations such as the COVID-19 pandemic.

The FDA “fast track” program is intended to expedite or facilitate the process for reviewing new products to treat serious or life-
threatening conditions and address unmet medical needs. Fast track designation applies to the combination of the product and the
specific indication for which it is being studied. Under the fast track program, the sponsor will have more frequent interactions with
the FDA during drug development, and may also submit sections of the NDA on a rolling basis to the FDA for review before
submitting the complete application. Fast track does not guarantee that a product will be reviewed more quickly or receive FDA
approval.

The FDA “breakthrough therapy” program is intended to expedite the development and review of drugs for serious or life-threatening
conditions. Preliminary clinical evidence must show that the drug may have substantial improvement over existing therapies on one or
more clinically significant endpoints. Although the drug does not have to address an unmet medical need, designation of breakthrough
therapy status carries all the “fast track” program features. Additionally, the breakthrough therapy program entitles the sponsor to
earlier and more frequent interaction with the FDA review team regarding development of nonclinical and clinical data, and allows the
FDA to offer product development and regulatory advice necessary to shorten the time for product approval. The breakthrough
therapy status does not guarantee a quicker development or review of the product, and does not ensure FDA approval.

The FDA also has a “priority review” program for products offering significant improvement in the treatment, diagnosis or prevention
of a disease. The goal of the priority review program is to shorten the review period to six months from the ten months required for
standard review. Any drug with breakthrough therapy, accelerated approval designation, or fast track can be granted priority review if
it meets the necessary criteria.

The FDA “accelerated approval” program is intended to expedite the development and review of products with the potential to treat
serious or life-threatening illnesses and provide meaningful therapeutic benefit over existing treatments. The program allows approval
of a product on the basis of adequate and well-controlled clinical studies establishing that the product has an effect on a surrogate
endpoint that is reasonably likely to predict a clinical benefit, or on the basis of an effect on a clinical endpoint that can be measured
earlier than survival or irreversible morbidity. As a condition of approval, the FDA generally requires that a sponsor of the product
perform adequate and well-controlled post-marketing clinical studies to establish safety and efficacy for the approved indication.
Failure to conduct such studies or failure of the studies to establish required safety and efficacy may result in revocation of approval.
The FDA also requires, as a condition for accelerated approval, pre-approval of promotional materials, which could adversely impact
the timing of the commercial launch or subsequent marketing of the product.

The FDA may also allow the use of unapproved medical products, or unapproved uses of approved medical products, under an
emergency use authorization, or EUA, to diagnose, treat, or prevent serious or life-threatening diseases or conditions when certain
statutory criteria have been met, including that there are no adequate, approved, and available alternatives. An EUA is a mechanism to
facilitate the availability and use of medical countermeasures during public health emergencies, such as the COVID-19
pandemic. Once submitted, the FDA will evaluate an EUA request and determine whether the relevant statutory criteria are met,
taking into account the totality of the scientific evidence about the drug that is available to FDA. EUAs can be terminated, revoked or
reissued, depending on the state of the public health emergency and new data about the drug.

Post-Approval Requirements

Any drug products for which we receive FDA approvals are subject to continuing regulation by the FDA. Certain requirements
include, among other things, record-keeping requirements, reporting of adverse experiences with the product, providing the FDA with
updated safety and efficacy information on an annual basis or more frequently for specific events, drug supply chain requirements,
product sampling and distribution requirements, complying with certain electronic records and signature requirements and complying
with FDA prescription drug promotion and advertising requirements. These promotion and advertising requirements include, among
others, standards for direct-to-consumer advertising, prohibitions against promoting drugs for uses or in patient populations that are
not described in the drug’s approved labeling (known as “off-label use”), rules for conducting industry-sponsored scientific and
educational activities and promotional activities involving the internet. Failure to comply with FDA requirements can have negative

consequences, including the immediate discontinuation of noncomplying materials, adverse publicity, enforcement letters from the
FDA, mandated corrective advertising or communications with doctors, and civil or criminal penalties. Although physicians may
prescribe legally available drugs for off-label uses, manufacturers may not market or promote such off-label uses.

We rely, and expect to continue to rely, on third parties for the production of clinical and commercial quantities of our product
candidates. Manufacturers of our product candidates are required to comply with applicable FDA manufacturing requirements
contained in the FDA’s cGMP regulations. These regulations require, among other things, quality control and quality assurance as
well as the corresponding maintenance of comprehensive records and documentation. Drug manufacturers and other entities involved
in the manufacture and distribution of approved drugs are also required to register their establishments and list any products they make
with the FDA and to comply with related requirements in certain states. These entities are further subject to periodic unannounced
inspections by the FDA and certain state agencies for compliance with cGMP and other laws. Accordingly, manufacturers must
continue to expend time, money and effort in the area of production and quality control to maintain cGMP compliance. Discovery of
problems with a product after approval may result in serious and extensive restrictions on a product, manufacturer or holder of an
approved NDA. These restrictions may include suspension of a product until the FDA is assured that quality standards can be met,
continuing oversight of manufacturing by the FDA under a “consent decree,” which frequently includes the imposition of costs and
continuing inspections over a period of many years, as well as possible withdrawal of the product from the market. In addition,
changes to the manufacturing process generally require prior FDA approval before being implemented. Other types of changes to the
approved product, such as adding new indications and additional labeling claims, are also subject to further FDA review and approval.

The FDA also may require post-marketing testing, known as Phase 4 testing, as well as risk minimization action plans and
surveillance to monitor the effects of an approved product or place conditions on an approval that could otherwise restrict the
distribution or use of the product.

U.S. Patent Term Restoration and Marketing Exclusivity

Drug Price Competition and Patent Term Restoration Act of 1984

Depending upon the timing, duration and specifics of the FDA approval of the use of our product candidates, some of our United
States patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of
1984, commonly referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent restoration term
of up to five years as compensation for patent term lost during federal regulatory review preceding the FDA regulatory review
process. However, patent term restoration cannot extend the remaining term of a patent beyond a total of 14 years from the product’s
approval date. The patent term restoration period is generally one-half the time between the effective date of an IND and the
submission date of an NDA plus the time between the submission date of an NDA and the approval of that application. Only one
patent applicable to an approved drug is eligible for the extension and the application for the extension must be submitted within 60
days of approval, prior to the expiration of the patent. The United States Patent and Trademark Office, in consultation with the FDA,
reviews and approves the application for any patent term extension or restoration. In the future, we may apply for restoration of patent
term for one of our currently owned or licensed patents to add patent life beyond its current expiration date, depending on the expected
length of the clinical trials and other factors involved in the filing of the relevant NDA. However, there is no guarantee that any such
application will be approved.

Federal Food, Drug and Cosmetic Act, or FDCA

Market exclusivity provisions under the FDCA, which are independent of patent status and any patent related extensions, can also
delay the submission or the approval of certain applications of other companies seeking to reference another company’s NDA. If the
new drug is a new chemical entity subject to an NDA, the FDCA provides a five-year period of non-patent marketing exclusivity
within the United States to the first applicant to obtain approval of an NDA for a new chemical entity. A drug is a new chemical entity
if the FDA has not previously approved any other new drug containing the same active moiety, which is the molecule or functional
group of a molecule responsible for the action of the drug substance. During the exclusivity period, the FDA may not accept for
review an abbreviated new drug application, or ANDA, or a so-called Section 505(b)(2) NDA, submitted by another company for
another version of such drug where the applicant does not own or have a legal right of reference to all the data required for approval.
However, such an application may be submitted after four years if it contains a certification of patent invalidity or non-infringement to
one of the patents listed with the FDA by the innovator NDA holder. The FDCA also provides three years of marketing exclusivity for
an NDA, or supplement to an existing NDA if new clinical investigations, other than bioavailability studies, that were conducted or
sponsored by the applicant are deemed by the FDA to be essential to the approval of the application, for example, new indications,
dosages or strengths of an existing drug. This three-year exclusivity covers only the conditions associated with the new clinical
investigations and does not prohibit the FDA from approving ANDAs for drugs containing the original active agent. Five-year and
three-year exclusivity will not delay the submission or approval of a full NDA. However, an applicant submitting a full NDA would
be required to conduct or obtain a right of reference to all of the preclinical studies and adequate and well-controlled clinical trials
necessary to demonstrate safety and effectiveness.

Other U.S. Healthcare Laws and Compliance Requirements

In the United States, 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, state attorney generals and state and local
governments.
At such time as we market, sell and distribute any products for which we obtain marketing approval, it is possible that our business
activities could be subject to scrutiny and enforcement under one or more federal or state health care fraud and abuse laws and
regulations. These fraud and abuse laws include:

•

The federal Anti-Kickback Law, which prohibits, among other things, knowingly or willingly offering, paying, soliciting
or receiving remuneration, directly or indirectly, in cash or in kind, to induce or reward the purchasing, leasing, ordering
or arranging for or recommending the purchase, lease or order of any health care items or service for which payment may
be made, in whole or in part, by federal health care programs such as Medicare and Medicaid;

The federal civil False Claims Act, which prohibits, among other things, individuals or entities from knowingly
presenting, or causing to be presented, a false or fraudulent claim for payment of government funds or knowingly making,
using or causing to be made or used, a false record or statement material to an obligation to pay money to the government
or knowingly concealing or knowingly and improperly avoiding, decreasing or concealing an obligation to pay money to
the federal government;

The federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, which imposes criminal liability for
knowingly and willfully executing a scheme to defraud any healthcare benefit program, knowingly and willfully
embezzling or stealing from a health care benefit program, willfully obstructing a criminal investigation of a health care
offense, or knowingly and willfully making false statements relating to healthcare matters;

The federal Physician Payment Sunshine Act, being implemented as the Open Payments Program, requires certain
pharmaceutical manufacturers to engage in extensive tracking of payments and other transfers of value to physicians and
teaching hospitals, and to submit such data to the Centers for Medicare and Medicaid Studies, or CMS, which will then
make all of this data publicly available on the CMS website; and

Analogous state laws and regulations, including state anti-kickback and false claims laws, which may apply to items or
services reimbursed under Medicaid and other state programs or, in several states, apply regardless of the payer, as well as
other state laws that require pharmaceutical companies to report expenses related to the marketing and promotion of
pharmaceutical products, prohibit certain gifts or payments to health care providers in the state, and/or require
pharmaceutical companies to implement compliance programs or marketing codes of conduct.

Violations of fraud and abuse laws may be punishable by significant criminal and/or civil sanctions, including fines and civil monetary
penalties, the possibility of exclusion from federal health care programs (including Medicare and Medicaid) and corporate integrity
agreements, which impose, among other things, rigorous operational and monitoring requirements on companies. Similar sanctions
and penalties also may be imposed upon executive officers and employees, including criminal sanctions against executive officers
under the so-called “responsible corporate officer” doctrine, even in situations where the executive officer did not intend to violate the
law and was unaware of any wrongdoing. Given the penalties that may be imposed on companies and individuals if convicted,
allegations of such violations often result in settlements even if the company or individual being investigated admits no wrongdoing.
Settlements often include significant civil sanctions, including fines and civil monetary penalties, and corporate integrity agreements.
If the government was to allege or convict us or our executive officers, employees or consultants of violating these laws, our business
could be harmed. In addition, private individuals have the ability to bring similar actions under some of the fraud and abuse laws
described above. Our activities could be subject to challenge for the reasons discussed above and due to the broad scope of these laws
and extensive enforcement of them by law enforcement authorities. Further, federal and state laws that require manufacturers to make
reports on pricing and marketing information could subject us to penalty provisions.

In addition, pricing and rebate programs must comply with the Medicaid rebate requirements of the Omnibus Budget Reconciliation
Act of 1990 and the Veterans Health Care Act of 1992, each as amended. If products are made available to authorized users of the
Federal Supply Schedule of the General Services Administration, additional laws and requirements apply. Under the Veterans Health
Care Act, or VHCA, drug companies are required to offer certain pharmaceutical products at a reduced price to a number of federal
agencies including the United States Department of Veterans Affairs and United States Department of Defense, the Public Health
Service and certain private Public Health Service—designated entities in order to participate in other federal funding programs
including Medicare and Medicaid. Recent legislative changes purport to require that discounted prices be offered for certain United
States Department of Defense purchases for its TRICARE program via a rebate system. Participation under the VHCA requires
submission of pricing data and calculation of discounts and rebates pursuant to complex statutory formulas, as well as the entry into
government procurement contracts governed by the Federal Acquisition Regulations.

In order to distribute products commercially, we must comply with state laws that require the registration of manufacturers and
wholesale distributors of pharmaceutical products in a state, including, in certain states, manufacturers and distributors who ship
products into the state even if such manufacturers or distributors have no place of business within the state. Some states also impose
requirements on manufacturers and distributors to establish the pedigree of product in the chain of distribution, including some states
that require manufacturers and others to adopt new technology capable of tracking and tracing product as it moves through the
distribution chain. Several states have enacted legislation requiring pharmaceutical companies to establish marketing compliance
programs, file periodic reports with the state, make periodic public disclosures on sales, marketing, pricing, clinical trials and other
activities, and/or register their sales representatives, as well as to prohibit pharmacies and other healthcare entities from providing
certain physician prescribing data to pharmaceutical companies for use in sales and marketing, and to prohibit certain other sales and
marketing practices. All of our activities are potentially subject to federal and state consumer protection and unfair competition laws.

Europe / Rest of World Government Regulation

In addition to regulations in the United States, we will be subject to a variety of regulations in other jurisdictions governing, among
other things, clinical trials and any commercial sales and distribution of our products.

Whether or not we obtain FDA approval for a product, we must obtain the requisite approvals from regulatory authorities in foreign
countries prior to the commencement of clinical trials or marketing of the product in those countries. Certain countries outside of the
United States have a similar process that requires the submission of a clinical trial application much like the IND prior to the
commencement of human clinical trials. In the European Union, for example, a clinical trial application, or CTA, must be submitted to
each country’s national health authority and an independent ethics committee, much like the FDA and IRB, respectively. Once the
CTA is approved in accordance with a country’s requirements, clinical trials may proceed.

The requirements and process governing the conduct of clinical trials, product licensing, pricing and reimbursement vary from country
to country. In all cases, the clinical trials are conducted in accordance with International Conference on Harmonisation (ICH) / WHO
Good Clinical Practice standards and the applicable regulatory requirements and the ethical principles that have their origin in the
Declaration of Helsinki.

To obtain regulatory approval of an investigational drug under European Union regulatory systems, we must submit a marketing
authorization application to the European Medicines Agency, or the EMA. The application used to file an NDA in the United States is
similar to that required in the European Union, with the exception of, among other things, country-specific document requirements.

For other countries outside of the European Union, such as countries in Eastern Europe, Latin America or Asia, the requirements
governing the conduct of clinical trials, product licensing, pricing and reimbursement vary from country to country. In all cases, again,
the clinical trials are conducted in accordance with GCPs and the applicable regulatory requirements and the ethical principles that
have their origin in the Declaration of Helsinki.

If we fail to comply with applicable foreign regulatory requirements, we may be subject to, among other things, fines, suspension or
withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

Pharmaceutical Coverage, Pricing and Reimbursement

Significant uncertainty exists as to the coverage and reimbursement status of any product candidates for which we obtain regulatory
approval. In the United States 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. Third-party payors include
government health administrative authorities, managed care providers, private health insurers and other organizations. The process for
determining whether a payor will provide coverage for a drug product may be separate from the process for setting the price or
reimbursement rate that the payor will pay for the drug product. Third-party payors may limit coverage to specific drug products on an
approved list, or formulary, which might not include all of the FDA-approved drug products for a particular indication. Third-party
payors are increasingly challenging the price and examining the medical necessity and cost-effectiveness of medical products and
services, in addition to their safety and efficacy. In recent years, both the Federal and State governments are increasingly considering
and adopting laws that exert greater influence over the price of prescription drugs. For example, a number of states are increasingly
using more aggressive price control tools such as Prescription Drug Affordability Boards that have the authority to conduct
affordability reviews and establish upper payment limits. The Inflation Reduction Act passed by Congress in 2022 (discussed below),
authorized the Centers for Medicare and Medicaid Services, or CMS, to begin negotiating the prices on certain drugs based on factors
such as research & developments costs and the health economic impact of a particular therapy. We may need to conduct expensive
pharmaco-economic studies to demonstrate the medical necessity and cost-effectiveness of our products, in addition to the costs
required to obtain the FDA approvals. Our product candidates may not be considered medically necessary or cost-effective. A payor’s
decision to provide coverage for a drug product does not imply that an adequate reimbursement rate will be approved. Adequate third-
party reimbursement may not be available to enable us to maintain price levels sufficient to realize an appropriate return on our
investment in product development. In certain circumstances, we may need to negotiate discounts on a drug product in order to ensure
adequate formulary access for patients.

In 2003, the United States government enacted legislation providing a partial prescription drug benefit for Medicare recipients, which
became effective at the beginning of 2006. Government payment for some of the costs of prescription drugs may increase demand for
any products for which we receive marketing approval. However, to obtain payments under this program, we would be required to sell
products to Medicare recipients through private prescription drug plans that contract with the federal government and adhere to certain
minimum requirements.

The Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act, collectively known
as the Affordable Care Act, or ACA, substantially changed the way healthcare is financed by both governmental and private insurers,
and significantly impacted the pharmaceutical industry.

Since its adoption, the ACA contains a number of provisions, including those governing enrollment in federal healthcare programs,
reimbursement changes and fraud and abuse, which have affected existing government healthcare programs and have resulted in the
development of new programs, including Medicare payment tied to performance. Additionally, the Affordable Care Act:

•

increased the minimum level of Medicaid rebates payable by manufacturers of brand-name drugs from 15.1% to 23.1%;

required collection of rebates for drugs paid by Medicaid managed care organizations;

required manufacturers to participate in a coverage gap discount program, under which they must agree to offer 50%
point-of-sale discounts off negotiated prices of applicable brand drugs to eligible beneficiaries during their coverage gap
period, as a condition for the manufacturer’s outpatient drugs to be covered under Medicare Part D, beginning January
2011; and

imposed a non-deductible annual fee on pharmaceutical manufacturers or importers who sell “branded prescription drugs”
to specified federal government programs.

Several states have not implemented the provisions of the ACA that involve the expansion of Medicaid eligibility to low-income
adults. While the United States Supreme Court recently rejected the latest challenge to the constitutionality of the ACA, it is possible
that other legislative efforts may seek to modify it. In addition, other legislative changes have been proposed since the Affordable Care
Act was enacted.

There has been increasing legislative and enforcement interest in the United States with respect to drug pricing practices. For example,
the Inflation Reduction Act of 2022, or IRA, introduces some of the most significant changes to Medicare payment for prescription
drugs since the ACA. Among its many provisions, the IRA authorizes the Medicare program to negotiate pricing for certain high-cost
and/or high-volume drugs, including physician-administered and self-administered drugs, that have been on the market for a minimum
amount of time without generic competition. Each year, beginning with calendar year 2026, the Secretary of the Department of Health
and Human Services will implement a negotiated price, known as the “Maximum Fair Price”, or MFP, that will be made public and
apply to the drug’s Medicare utilization if the drug is among the top 10 drugs with the highest Medicare spending. Manufacturers who
fail to offer the MFP, or fail to come to the table to negotiate after the Secretary has determined their drug is eligible for negotiation,
will incur an excise tax of up to 95% for each sale of the drug in the United States. Depending on the share of Medicare spending each
year that is attributed to MAVYRET or any other drug we may develop or out-license, and whether or not those drugs become eligible
for Medicare negotiation, those drugs and our revenue may be adversely impacted by this provision.

The IRA also will require manufacturers, beginning in 2023, to rebate the Medicare program for Medicare utilization of Part B and
Part D drugs that have price increases faster than the rate of inflation. The benchmark to which price increases are compared will vary
depending on the drug. Although manufacturers are generally familiar with inflation rebates under the Medicaid program, where they
have existed for decades, the IRA represents the first time that the Centers for Medicare and Medicaid Services, or CMS, has extended
inflation rebates to the Medicare program.

The IRA also redesigns the Medicare prescription drug benefit in several important ways, beginning in calendar year 2024. First, the
IRA places an annual out-of-pocket cap on Medicare beneficiary cost sharing amounts, which will take effect in calendar year 2024
before the full benefit redesign. Previously, beneficiaries’ out-of-pocket costs were uncapped, even if heavily subsidized. Second, the
IRA requires that manufacturers share in the cost of prescription drugs throughout the prescription drug benefit, beginning in calendar
year 2025. Previously manufacturers only needed to offer discounted pricing for a single phase of the prescription drug benefit. Also
in calendar year 2025, the IRA introduces a new $2,000 out-of-pocket maximum in the Part D program for beneficiaries. Finally, the
IRA shifts the majority of liability in the “catastrophic phase”—the phase of the prescription drug benefit that only the costliest of
Medicare beneficiaries enter—to the private Part D plans, thereby encouraging them to better manage costs. Previously, the Federal
government incurred the vast majority of liability during the catastrophic phase. Together, these changes to the Medicare prescription
drug benefit will create new pricing dynamics for payers and manufacturers.

As noted above, state legislatures are also increasingly considering and adopting laws that exert greater influence over the price of
prescription drugs. In recent years, many states have passed cost transparency and pharmaceutical pricing laws. These laws often
require manufacturers to report certain product information or other financial data to the state. State are expected to continue their

focus on pharmaceutical pricing and will increasingly move to more aggressive price control tools such as Prescription Drug
Affordability Boards that have the authority to conduct affordability reviews and establish upper payment limits.

Different pricing and reimbursement schemes exist in other countries. In the European Union, governments influence the price of
pharmaceutical products through their pricing and reimbursement rules and control of national healthcare systems that fund a large
part of the cost of those products to consumers. Some jurisdictions operate positive and negative list systems under which products
may only be marketed once a reimbursement price has been agreed. To obtain reimbursement or pricing approval, some of these
countries may require the completion of clinical trials that compare the cost-effectiveness of a particular product candidate to currently
available therapies. Other member states allow companies to fix their own prices for medicines but monitor and control company
profits. The downward pressure on healthcare costs in general, particularly prescription drugs, has become very intense. As a result,
increasingly high barriers are being erected to the entry of new products. In addition, in some countries, cross-border imports from
low-priced markets exert a commercial pressure on pricing within a country.

The marketability of any drug candidates for which we receive regulatory approval for commercial sale may suffer if the government
and third-party payers fail to provide adequate coverage and reimbursement. In addition, emphasis on managed care in the United
States has increased and we expect will continue to increase the pressure on pharmaceutical drug pricing. Coverage policies and third-
party reimbursement rates may change at any time. Even if favorable coverage and reimbursement status is attained for one or more
products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in
the future.

Research and Development

Our research and development expenses were $163.5 million, $164.5 million and $174.1 million for the fiscal years ended September
30, 2023, 2022, and 2021, respectively.

Manufacturing

We do not have our own manufacturing capabilities, except with respect to limited amounts of active pharmaceutical ingredients
needed for preclinical development. To date, we have relied on third-party manufacturers, including manufacturers in China, for
supply of active pharmaceutical ingredients and ingredients for use in clinical trials of our product candidates. We also expect that in
the future we will rely on such manufacturers to produce commercial quantities of any product candidates that we commercialize
ourselves. Manufacturing for glecaprevir is conducted by AbbVie. Wherever possible, we seek to identify multiple suppliers for raw
materials and key intermediaries to be used in our manufacturing process.

Sales and Marketing

We currently do not have any commercialization or sales and marketing capabilities, and currently have no fixed plans to invest in or
build such capabilities internally. We have partnered our protease inhibitor compounds for HCV with AbbVie. We may also partner or
collaborate with, or license commercial rights to, other larger pharmaceutical or biopharmaceutical companies to support the
development of one or more of our wholly-owned product candidates through late-stage clinical development and, if successful,
commercialization. However, we still retain all commercial rights to our independent programs and we will continue to evaluate our
alternatives for commercializing them once they are more advanced in their clinical development.

Our Corporate Information

We are a Delaware corporation, incorporated in 1995. Our principal executive offices are located at 500 Arsenal Street, Watertown,
Massachusetts 02472, and our telephone number is (617) 607-0800. Our web site address is http://www.enanta.com.

Segment Information

We provide segment information in Note 2 to our Consolidated Financial Statements included in Item 8 of this report. We are
incorporating that information into this section by this reference.

Human Capital Resources

As of September 30, 2023, we had 145 full-time employees, 70 of whom hold Ph.D. or M.D. degrees and an additional 35 of whom
hold a master's degree or other post-graduate degree. We consider the intellectual capital of our employees to be an essential driver of
our business and key to our future prospects. Historically we have had relatively low turnover of employees, but as the number of
biotechnology and pharmaceutical companies in the Boston area has increased dramatically, we have experienced an increase in the
number of employees leaving for other opportunities. Given our financial resources and our track record, we continue to be able to fill
the vacated positions. We also monitor our compensation programs closely and provide what we consider to be a very competitive
mix of compensation and insurance benefits for all our employees, as well as participation in our equity programs. None of our

employees is subject to a collective bargaining agreement or represented by a trade or labor union. We consider our relations with our
employees to be good.

Available Information

Our Internet website address is http://www.enanta.com. Through our website, we make available, free of charge, our annual report on
Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and any amendments to those reports, as well as proxy
statements, and, from time to time, other documents as soon as reasonably practicable after we electronically file such material with,
or furnish it to, the Securities and Exchange Commission, or SEC. These SEC reports can be accessed through the “Investors” section
of our website. The information found on our website is not part of this or any other report we file with or furnish to the SEC.

In addition, the SEC maintains an Internet website that contains reports, proxy and information statements, and other information
regarding Enanta Pharmaceuticals, Inc. and other issuers that file electronically with the SEC. The SEC’s Internet website address is
http://www.sec.gov.

ITEM 1A. RISK FACTORS

RISK FACTORS

Our business faces significant risks and uncertainties. Certain factors may have a material adverse effect on our business prospects,
financial condition and results of operations, and you should carefully consider them. Accordingly, in evaluating our business, we
encourage you to consider the following discussion of risk factors, in its entirety, in addition to other information contained in or
incorporated by reference into this Annual Report on Form 10-K and our other public filings with the SEC. Other events that we do
not currently anticipate or that we currently deem immaterial may also affect our business, prospects, financial condition and results of
operations.

Risks Related to Our Business

We will require substantial additional funding to achieve our goals. A failure to obtain this funding when needed could force us to
delay, limit, reduce or terminate some or all of our product development efforts.

We will continue to expend substantial resources discovering and developing our proprietary product candidates. These expenditures
will exceed our royalty revenues from our AbbVie collaboration and will include costs associated with research and development,
preclinical manufacturing of product candidates, conducting preclinical experiments and clinical trials and obtaining regulatory
approvals, as well as commercializing any products later approved for sale. Our future capital requirements depend on many factors,
including:

•

the number and characteristics of our research and development programs;

the scope, progress, results and costs of researching and developing our product candidates on our own, including
conducting advanced clinical trials;

our ability to establish new collaborations, licensing or other arrangements, if any, and the financial terms of such
arrangements;

the amount of our retained portion of royalties generated from MAVYRET/MAVIRET sales under our existing
collaboration with AbbVie;

delays and additional expenses in our clinical trials;

the cost of manufacturing our product candidates for clinical development and any products we successfully
commercialize independently;

opportunities to in-license or otherwise acquire new technologies and therapeutic candidates;

costs associated with prosecuting our patent infringement suit regarding use of a coronavirus 3CL protease inhibitor in
Paxlovid, Pfizer’s antiviral treatment for COVID-19;

the timing of, and the costs involved in, obtaining regulatory approvals for any product candidates we develop
independently;

the cost of commercialization activities, if any, of any product candidates we develop independently that are approved for
sale, including marketing, sales and distribution costs;

the timing and amount of any sales of our product candidates, if any, or royalties thereon;

the costs involved in preparing, filing, prosecuting, maintaining, defending and enforcing patents, including any litigation
costs and the outcomes of any such litigation; and

potential fluctuations in foreign currency exchange rates.

Accordingly, if we do not generate sufficient funding from our existing collaboration and any future collaborations, we will need to
obtain additional funding to support our operations. Additional funds may not be available if and when we need them, on terms that
are acceptable to us, or at all. Our ability to raise funds will depend on financial, economic and market conditions and other factors,
many of which are beyond our control. If adequate funds are not available to us on a timely basis, we may be required to delay, limit,
reduce or terminate preclinical studies, clinical trials or other research and development activities for one or more of our product
candidates.

Our revenues are dependent upon royalty revenues derived from AbbVie’s net sales of its MAVYRET/MAVIRET regimen for
HCV, which includes our protease inhibitor, glecaprevir. If AbbVie is unable to maintain sales of this regimen at or above current
levels of sales, our royalty revenues will be adversely affected.

AbbVie’s MAVYRET/MAVIRET regimen continues to be a leading HCV treatment in the U.S. and several market geographies in
developed countries where it is approved. While commercialization of this regimen is exclusively in AbbVie’s control without any
required input from us, we believe it is possible that prices will decline further due to payors obtaining additional discounts or
competitive market dynamics. For example, the states of Louisiana and Washington have negotiated a blanket price for one of the
HCV drug companies to treat all patients in one or more state programs (e.g. Medicaid). Gilead has been awarded the contract in
Louisiana and other states and AbbVie has been awarded the contract in Washington and other states. In addition, Gilead has been
able to access the Medicaid market at a lower price point to build its market share by using an authorized generic version of its HCV
regimen branded as Epclusa®. It is unknown whether these programs or other programs that states may adopt could have any further
impact on MAVYRET/MAVIRET sales. There may also be fluctuations in AbbVie’s market share over time due to these and other
competitive actions by Gilead.

In addition, in light of continued fiscal crises experienced by several countries in the European Union and Japan, governments have
announced or implemented measures to manage and reduce healthcare expenditures. AbbVie may experience global pricing pressure
for its MAVYRET/MAVIRET regimen from such measures, which may be reflected in larger discounts or rebates on its regimens or
delayed reimbursement. Also, private and public payors may choose to exclude AbbVie’s MAVYRET/MAVIRET regimen from their
formulary coverage lists or limit the types of patients for whom coverage will be provided. Any such change in formulary coverage,
discounts or rebates or reimbursement for MAVYRET/MAVIRET would negatively affect the demand for this regimen and our
royalty revenue derived from its sales.

In addition, AbbVie has the right to make decisions regarding the commercialization of licensed products without consulting us. For
example, in 2018 AbbVie entered into a royalty-free licensing agreement with the Medicines Patent Pool to accelerate access to
generic versions of MAVYRET/MAVIRET in 99 low- and middle-income countries and territories. AbbVie may also make decisions
with which we do not agree. If AbbVie acts in a manner that is not in our best interest, then it could adversely affect our royalty
revenues.

We and AbbVie face substantial competition in the markets for HCV drugs, and there are many companies developing potential
therapies for RSV, SARS-CoV-2, and HBV which may result in others discovering, developing or commercializing products before
we do or doing so more successfully than we do.

The pharmaceutical and biotechnology industries are intensely competitive and rapidly changing. Many large pharmaceutical and
biotechnology companies, academic institutions, governmental agencies and other public and private research organizations are
commercializing or pursuing the development of products that target HCV, RSV, SARS-CoV-2 and HBV and other viral infections or
diseases that we may target in the future. Many of our competitors have substantially greater commercial infrastructure and greater
financial, technical and personnel resources than we have, as well as drug candidates in late-stage clinical development.

In all the disease areas currently in the focus of our research and development efforts, there are other companies with product
candidates that are more advanced than ours. Our competitors may succeed in developing these product candidates or others and
obtaining regulatory approval before we can do so with any of our product candidates. If we are not “first to market” with one of our
product candidates in one or more of these disease indications, our competitive position could be compromised because it may be
more difficult for us to obtain marketing approval for that product candidate and market acceptance of that product candidate as a
follow-on competitor. In addition, any new product that competes with an approved product typically must demonstrate compelling
advantages in efficacy, convenience, tolerability or safety, or some combination of these factors, to gain regulatory approvals,
overcome price competition and be commercially successful.

RSV, COVID-19 and HBV represent competitive therapeutic areas.

For RSV, there are currently no safe and effective therapies for already established RSV infection. Several companies are seeking to
develop antiviral treatments for RSV infection in adult and pediatric patients. Ark Biosciences, Pfizer/ReViral (acquired in June 2022)
and Merck all have compounds in clinical development. Synagis, a prophylactic, monoclonal-antibody-based treatment from
AstraZeneca, which is commercialized by AbbVie outside the U.S., is approved for infants considered at high risk for RSV infection;
however, studies have found that most young children with RSV infection were previously healthy, and thus would not normally be
prescribed prophylactic treatment. AstraZeneca/Sanofi and Merck are developing long-acting versions of the monoclonal antibody for
prophylaxis use in infants. In addition, a number of companies have RSV vaccines in development, primarily directed at prevention of
RSV infection, and some companies are also evaluating vaccines in a therapeutic mode for treatment of established RSV infection.

Currently, there are two Emergency Use Authorizations of oral antiviral treatments for non-hospitalized, high-risk patients with
SARS-CoV-2 infection: PAXLOVID™, a 3CL protease inhibitor (nirmatrelvir) boosted with ritonavir, and LAGEVRIO™
(molnupiravir), a polymerase inhibitor. Additionally, there are companies developing oral direct acting antivirals for SARS-CoV-2

that are currently in global Phase 3 studies include Shionogi, Atea, and Gilead (an oral formulation of remdesivir), as well as
additional compounds in Phase 1 studies.

While there are antiviral medications prescribed for HBV that can suppress HBV DNA, they generally have low cure rates, resulting
in the need for lifelong treatment. Many companies are seeking to develop new HBV drugs that alone or in combination with other
mechanisms could lead to a functional cure for HBV. Vir, GSK, Arbutus, and Roche have multiple combination regimens under
investigation in later stage clinical studies. In addition, a number of companies have Phase 1 or earlier stage HBV programs.

In the chronic HCV market, we expect AbbVie’s MAVYRET/MAVIRET to continue to face intense competition due to existing
approved HCV products. AbbVie’s MAVYRET/MAVIRET regimen currently faces competition in various world markets and
subpopulations of HCV from Gilead’s Epclusa® (a fixed dose combination of sofosbuvir and velpatasvir), Vosevi® (a triple
combination therapy of sofosbuvir, velpatasvir and voxilaprevir approved by the FDA for specified sofosbuvir -treatment failures and
NS5A-inhibitor treatment failures) and Harvoni® (a fixed-dose combination of sofosbuvir and ledipasvir); and to a lesser extent -
Merck’s Zepatier® (a fixed-dose combination of grazoprevir and elbasvir). Gilead launched authorized generic versions of Epclusa
and Harvoni through its subsidiary, Asegua Therapeutics, LLC, which have had an impact on the competitive landscape. For example,
the state of Louisiana selected Asegua as their HCV subscription model pharmaceutical partner to provide the state with unrestricted
access to its direct-acting antiviral medication.

We have not developed independently any approved products and we have limited clinical development experience, which makes it
difficult to assess our ability to develop and commercialize our product candidates.

AbbVie has been responsible for all of the clinical development of our HCV protease inhibitor products. We have not yet
demonstrated an ability to address successfully many of the risks and uncertainties associated with late-stage clinical development,
regulatory approval and commercialization of therapeutic products such as the ones we plan to develop independently. For example, to
execute our business plan for the development of our independent RSV and HBV programs, we will need to successfully:

•

execute clinical development of our product candidates and demonstrate acceptable safety and efficacy for them alone or
in combination with other drugs or drug candidates;

obtain required regulatory approvals for the development and commercialization of our product candidates;

develop and maintain any future collaborations we may enter into for any of these programs;

obtain and maintain patent protection for our product candidates and freedom from infringement of intellectual property of
others;

establish acceptable commercial manufacturing arrangements with third-party manufacturers;

build and maintain robust sales, distribution and marketing capabilities, either independently or in collaboration with
future collaborators;

gain market acceptance for our product candidates among physicians, payors and patients; and

manage our spending as costs and expenses increase due to clinical trials, regulatory approvals and commercialization.

If we are unsuccessful in accomplishing these objectives, we may not be able to successfully develop and commercialize our product
candidates and expand our business or continue our operations.

If we are not successful in developing EDP-938, EDP-323, or in obtaining a partner to advance EDP-235, or in discovering
further product candidates, our ability to expand our business and achieve our strategic objectives will be impaired.

Much of our internal research is at preclinical stages. Research programs designed to identify product candidates require substantial
technical, financial and human resources, whether or not any product candidates are ultimately identified. Our research programs may

initially show promise in identifying additional potential product candidates, yet fail to yield product candidates for clinical
development or commercialization for many reasons, including the following:

•

the research methodology used may not be successful in identifying additional potential product candidates;

competitors may develop alternatives that render our product candidates less commercially viable or obsolete;

competitors may obtain intellectual property protection that effectively prevents us from developing a product candidate;

a product candidate may, on further study, be shown not to be an effective treatment in humans or to have harmful side
effects or other characteristics that indicate it is unlikely to be effective or otherwise does not meet applicable regulatory
criteria; and

a product candidate may not be capable of being produced in commercial quantities at an acceptable cost, or at all.

Additional drug candidates that we may develop will require significant research, preclinical and clinical studies, regulatory approvals
and commitments of resources before they can be commercialized. We cannot give assurance that our research will lead to the
discovery of any additional drug candidates that will generate additional revenue for us. If we are unable to identify additional
compounds suitable for preclinical and clinical development, we may not be able to obtain sufficient product revenue in future
periods, which likely would result in significant harm to our financial position and adversely impact our stock price.

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

Our success depends in part on our continued ability to attract, retain and motivate highly qualified management, clinical and
scientific personnel. We are highly dependent upon our senior management, particularly Jay R. Luly, Ph.D., our Chief Executive
Officer and President, Yat Sun Or, Ph.D., our Senior Vice President, Research and Development and Chief Scientific Officer, and
Scott T. Rottinghaus, M.D., our Senior Vice President and Chief Medical Officer whom we hired in August 2022, as well as other
employees and consultants. Although none of Drs. Luly, Or, or Rottinghaus has informed us to date that he expects to retire or resign
in the near future, the loss of the services of any of these individuals or one or more of our other members of senior management could
delay or prevent the successful development of our product candidates.

While we have not historically experienced unique difficulties attracting and retaining qualified employees, we could experience such
problems in the future. For example, competition for qualified personnel in the biotechnology and pharmaceutical fields is intense. In
addition, we will need to hire additional personnel as we expand our clinical development and ultimately seek regulatory approvals
and prepare for commercial activities. We may not be able to attract and retain quality personnel on acceptable terms.

We may encounter difficulties expanding our operations successfully to advance our product candidates.

As we seek to advance our product candidates through clinical trials, we will need to expand our development, regulatory,
manufacturing, marketing and sales capabilities or contract with third parties to obtain these capabilities. As our pipeline expands, we
expect that we will need to manage additional relationships with various strategic partners, suppliers and other third parties. Future
growth will impose significant added responsibilities on members of management. Our future financial performance and our ability to
commercialize our product candidates and to compete effectively will depend, in part, on our ability to manage any future growth
effectively. To that end, we must be able to manage our development efforts and clinical trials effectively and hire, train and integrate
additional management, administrative and sales and marketing personnel. We may not be able to accomplish these tasks, and our
failure to accomplish any of them could prevent us from successfully growing our company.

Risks Related to Development, Clinical Testing and Regulatory Approval of Our Product Candidates

Clinical drug development involves a lengthy and expensive process with uncertain timelines and uncertain outcomes. Any
ongoing or future clinical trials of our product candidates may fail to demonstrate sufficient safety and efficacy. If clinical trials of
any of our proprietary product candidates are prolonged or delayed or fail, we may be unable to commercialize our product
candidates on a timely basis or ever.

Clinical testing is expensive and, depending on the stage of development, can take a substantial time period to complete. Its outcome
is inherently uncertain, and failure can occur at any time during clinical development. None of our product candidates in our pipeline
other than glecaprevir, which was clinically developed by AbbVie, has yet to advance beyond Phase 2 clinical trials. Any ongoing or
future clinical trials of our product candidates may fail to demonstrate sufficient safety and efficacy. Moreover, regulatory and
administrative delays, including those caused by the COVID-19 pandemic, for any product candidate in our pipeline may adversely
affect our or any future collaborator’s clinical development plans and jeopardize our or any future collaborator’s ability to attain
product approval, commence product sales and compete successfully against other therapies.

Clinical trials can be delayed for a variety of reasons, including delays related to:

•

reaching an agreement on acceptable terms with prospective contract research organizations, or CROs, and clinical trial
sites, the terms of which can be subject to extensive negotiation and may vary significantly among different CROs and
trial sites;

failure of third-party contractors, such as CROs, or investigators to comply with regulatory requirements;

failure to obtain on a timely basis, or at all, the necessary approvals from regulators or institutional review boards, or
IRBs, to commence a clinical trial at a prospective trial site, or their suspension or termination of a clinical trial once
commenced;

difficulty in recruiting suitable patients to participate in a trial;

the broader impact of COVID-19 on the incidence of other viruses (e.g., RSV), and the political and socio-economic
stability affecting our clinical trial sites generally;

seasonality and variations in the incidence of infection year to year (e.g. RSV) affecting enrollment in clinical trials;

difficulty in having patients complete a trial or return for post-treatment follow-up;

clinical sites deviating from trial protocol or dropping out of a trial;

problems with drug product or drug substance storage and distribution;

having to add new clinical trial sites;

our inability to manufacture, or obtain from third parties, adequate supply of drug product sufficient to complete our
preclinical studies and clinical trials;

changes in governmental or regulatory administration;

lack of clear guidance or changes in regulatory requirements, policy and guidelines, including guidelines specifically
addressing requirements for the development of treatments for RSV, COVID-19 or HBV infection;

difficulty in obtaining and maintaining adequate insurance coverage;

program discontinuations or clinical holds for a program of a competitor, which could increase the level of regulatory
scrutiny or delay data review or other response times by regulators with respect to one of our programs in the same class
as the competitor’s program; or

varying interpretations of data by the FDA, the EMA and similar foreign regulatory agencies.

We could also encounter delays if a clinical trial is suspended or terminated by us, by the IRBs of the institutions in which such trial is
being conducted, by any Data Safety Monitoring Board, or DSMB, for such trial, or by the FDA, the EMA or other regulatory
authorities. Such authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the
clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site
by the FDA or other regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side
effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions or lack of
adequate funding to continue the clinical trial. In addition, delays can occur due to safety concerns arising from trials or other clinical
data regarding another company’s product candidate in the same compound class as one of ours. If we or any future collaborators
experience delays in the completion of, or termination of, any clinical trial of one of our product candidates, the commercial prospects
of the product candidate will be harmed, and our ability to commence product sales and generate product revenues from the product
candidate will be delayed. In addition, any delays in completing our clinical trials will increase our costs in the long term and slow
down our product candidate development and approval process. Any of these occurrences may harm our business, financial condition
and prospects significantly. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of
clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates.

EDP-938 or EDP-323, or any other product candidate emerging from our current research programs, may have undesirable side
effects which may delay or prevent marketing approval, or, if approval is received, require our product candidate to be taken off
the market, require us to include safety warnings or otherwise limit sales.

In our RSV program, we are developing inhibitors of the N-protein and L-protein. No inhibitor of the RSV N- or L-protein has
progressed beyond a Phase 2 clinical trial, so we are not yet able to assess the potential liabilities of an N-protein or L-protein inhibitor

in large scale studies or in the general population. In addition, the principal target populations in RSV, namely infants, the elderly, and
the immunocompromised, represent sensitive patient populations that could be more prone to adverse effects of therapy.

If any of our product candidates receives marketing approval and we or others later identify undesirable or unacceptable side effects
caused by such products:

•

regulatory authorities may require the addition of labeling statements, specific warnings, a contraindication or field alerts
to physicians and pharmacies;

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

we may be subject to limitations on how we may promote the product;

the product may be subject to additional distribution restrictions under a REMS, if required by the FDA;

sales of the product may decrease significantly;

regulatory authorities may require us to take our approved product off the market;

we may be subject to litigation or product liability claims; and

our reputation and our stock price may suffer.

Any of these events could prevent us from achieving or maintaining market acceptance of the affected product or could substantially
increase commercialization costs and expenses, which in turn could delay or prevent us from generating significant revenue from the
sale of any product we develop.

If we are required to suspend or discontinue clinical trials due to side effects or other safety risks associated with our product
candidates, or if we are required to conduct studies on the long-term effects associated with the use of any of those product
candidates, then commercialization any of those product candidates could be delayed or halted.

Clinical trials involving our product candidates may be suspended or terminated at any time for a number of safety-related reasons.
For example, we may voluntarily suspend or terminate clinical trials if at any time one of our product candidates, or a combination
therapy including any of them, presents an unacceptable safety risk to the clinical trial patients. In addition, IRBs or regulatory
agencies may order the temporary discontinuation or termination of clinical trials at any time if they believe that the clinical trials are
not being conducted in accordance with applicable regulatory requirements, including if they present an unacceptable safety risk to
patients. Administering any product candidate to humans may produce undesirable side effects. The existence of undesirable side
effects resulting from any of our product candidates, or a combination therapy including any of them, could cause us or regulatory
authorities, such as the FDA or EMA, to interrupt, delay or halt clinical trials of our product candidates and could result in the FDA or
EMA or other regulatory agencies denying further development or approval of our product candidates for any or all targeted
indications. This, in turn, could prevent us from commercializing our product candidates.

Results of earlier clinical trials may not be predictive of the results of later-stage clinical trials.

To date we have only tested our product candidates through initial Phase 2 studies. The results of preclinical studies and these early
clinical trials of our product candidates may not be predictive of the results of later-stage clinical trials, if any. In addition, results of
Phase 3 clinical trials in one or more ethnic groups are not necessarily indicative of results in other ethnic groups. Product candidates
in later stages of clinical trials may fail to show the desired safety and efficacy results despite having progressed through preclinical
studies and initial clinical trials. For example, several companies engaged in clinical development in the disease areas we are also
engaged in have suffered significant setbacks in advanced clinical trials due to adverse safety profiles or lack of efficacy,
notwithstanding promising results in earlier studies. Similarly, future clinical trial results may not be successful for these or other
reasons.

Product candidate development risk is heightened by any changes in the planned clinical trials compared to the completed clinical
trials. As product candidates are developed through preclinical studies and early-stage and late-stage clinical trials towards approval
and commercialization, it is customary that various aspects of the development program, such as manufacturing and formulation, are
altered along the way in an effort to optimize processes and results. Such changes carry the risk that they will not achieve these
intended objectives. Any of these changes could make the results of planned clinical trials or other future clinical trials we may initiate
less predictable and could cause our product candidates to perform differently, which could delay completion of clinical trials, delay
approval of our product candidates and/or jeopardize our ability to commence product sales and generate revenues.

The regulatory approval processes of the FDA, the EMA and other comparable foreign authorities are lengthy, time-consuming
and inherently unpredictable, and if we are ultimately unable to obtain timely regulatory approval for our product candidates, our
business will be substantially harmed.

The regulatory approval process is expensive and, while the time required to gain FDA and foreign regulatory approval is uncertain, it
may take years. Regulatory approvals are unpredictable and depend upon numerous factors, including the substantial discretion of the
regulatory authorities. In addition, approval policies, regulations, or the type and amount of preclinical and clinical data necessary to
gain approval may change during the course of a product candidate’s clinical development and may vary among jurisdictions. We may
be required to undertake and complete certain additional preclinical studies to generate toxicity and other data required to support the
submission of a New Drug Application, or NDA, to the FDA or comparable application to other regulatory authorities. AbbVie
obtained all regulatory approvals for its paritaprevir-containing regimens and for MAVYRET/MAVIRET, which contains glecaprevir.
We have not obtained regulatory approval by ourselves for any of our wholly-owned product candidates and it is possible that none of
our existing product candidates or any of our future product candidates will ever obtain regulatory approval. Furthermore, approval in
the United States by the FDA does not ensure approval by regulatory authorities in other countries or jurisdictions, and approval by
one foreign regulatory authority does not ensure approval by regulatory authorities in other foreign countries or by the FDA.
Our product candidates could fail to receive regulatory approval for many reasons, including the following:

•

the FDA, the EMA or other comparable foreign regulatory authorities may disagree with the design or implementation of
our clinical trials;

we may be unable to demonstrate to the satisfaction of the FDA, the EMA or other comparable foreign regulatory
authorities that a product candidate is safe and effective for its proposed indication;

the results of clinical trials may not meet the level of statistical significance required by the FDA, the EMA or other
comparable foreign regulatory authorities for approval;

we may be unable to demonstrate that a product candidate’s clinical and other benefits outweigh its safety risks;

the FDA, the EMA or other comparable foreign regulatory authorities may disagree with our interpretation of data from
preclinical studies or clinical trials;

the data collected from clinical trials of our product candidates may not be sufficient to support the submission of an NDA
or other submissions or to obtain regulatory approval in the United States or elsewhere;

the FDA or comparable foreign regulatory authorities may fail to approve the manufacturing processes or facilities of
third-party manufacturers with which we contract for clinical and commercial supplies of any of our product candidates;
and

the approval policies or regulations of the FDA, the EMA or other comparable foreign regulatory authorities may
significantly change in a manner rendering our clinical data insufficient for approval.

We cannot be assured that after spending substantial time and resources, we will obtain regulatory approvals in any desired
jurisdiction. Even if we were to obtain approval, regulatory authorities 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. Significant clinical trial delays could allow our competitors
to obtain marketing approval before we do or could in effect shorten the patent protection period during which we may have the
exclusive right to commercialize our product candidates. In addition, it may ultimately not be possible to achieve the prices intended
for our products. In many foreign countries, including those in the European Union, a product candidate must be approved for
reimbursement before it can be approved for sale in that country. Any of the foregoing scenarios could materially harm the
commercial prospects for our product candidates and our business.

The regulatory pathway for approval of a therapeutic treatment for COVID-19 such as EDP-235 is continually evolving and may
result in unexpected or unforeseen challenges and longer timelines than seen for earlier COVID-19 vaccines and therapeutics.

Initial COVID-19 vaccines, therapeutic antibodies and other therapeutics that demonstrated positive results in clinical trials have
moved rapidly through the FDA regulatory review and emergency use authorization, or EUA, process, as well as the review and
authorization process in a number of other jurisdictions, including the EU when there were no adequate, approved, and available
alternatives. The speed at which all parties acted to create and test many therapeutics for COVID-19 was unusual. The end of the
pandemic, however, may have changed those dynamics. Evolving priorities within the FDA or the regulatory authorities in other
jurisdictions, including changes based on new data regarding potential therapeutics of others, and new variants of the virus, may
significantly affect the regulatory timeline for further authorizations or approvals for therapeutics such as EDP-235. Accordingly, it is

still uncertain what will be the timelines or regulatory processes required for the authorization or approval of new treatments for
COVID-19, including EDP-235.

Even if we receive regulatory approval for any of our product candidates we develop independently, we will be subject to ongoing
FDA obligations and continued regulatory review in other jurisdictions, which may result in significant additional expense.
Additionally, our product candidates, if approved, could be subject to labeling and other restrictions and market withdrawal and we
may be subject to penalties if we or our collaborators fail to comply with regulatory requirements or experience unanticipated
problems with our products.

Any regulatory approvals that we receive for our product candidates we develop independently may be subject to limitations on the
approved indicated uses for which the product may be marketed or subject to certain conditions of approval, or may contain
requirements for potentially costly post-marketing testing, including Phase 4 clinical trials, and surveillance to monitor the safety and
efficacy of the product candidate.

In addition, if the FDA approves any of our product candidates, the manufacturing processes, labeling, packaging, distribution,
adverse event reporting, storage, advertising, promotion and recordkeeping for the product will be subject to extensive and ongoing
regulatory requirements. These requirements include submissions of safety and other post-marketing information and reports, as well
as continued compliance with current good manufacturing practices, or cGMP, and good clinical practices, or GCP, for any clinical
trials that we or our collaborators conduct post-approval. Later discovery of previously unknown problems with a product, including
adverse events of unanticipated severity or frequency, or with third-party manufacturers or manufacturing processes, or failure to
comply with regulatory requirements, may result in, among other things:

•

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

fines, warning letters or holds on any post-approval clinical trials;

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

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

injunctions or the imposition of civil or criminal penalties.

We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative
action, either in the United States or abroad. If we, or AbbVie in the case of any licensed HCV product, are slow or unable to adapt to
changes in existing requirements or the adoption of new requirements or policies, or if we or AbbVie are not able to maintain
regulatory compliance, our product candidates or AbbVie’s licensed HCV products may lose any marketing approval that may have
been obtained and we may not achieve or sustain profitability, which would adversely affect our business.

We may delay or terminate the development of a product candidate at any time if we believe the perceived market or commercial
opportunity does not justify further investment, which could materially harm our business and adversely affect our stock price.

Even though the results of preclinical studies and clinical trials that we have conducted or may conduct in the future may support
further development of one or more of our product candidates, we may delay, suspend or terminate the future development of a
product candidate at any time for strategic, business, financial or other reasons, including the determination or belief that the emerging
profile of the product candidate is such that it may not receive regulatory approvals in key markets, gain meaningful market
acceptance, otherwise provide any competitive advantages in its intended indication or market or generate a significant return to
stockholders. Such a delay, suspension or termination could materially harm our business, results of operations or financial condition.

Risks Related to Commercialization of Our Product Candidates

Unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives in the United States could
harm our business.

The regulations that govern marketing approvals, pricing and reimbursement for new drug products vary widely from country to
country. In the United States, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education
Affordability Reconciliation Act of 2010, collectively referred to as the ACA, has significantly changed the way healthcare is financed
by both governmental and private insurers. While we cannot predict what impact on federal reimbursement policies this law or any
amendment to it will continue to have in general or specifically on MAVYRET/MAVIRET or any product or regimen that we may
commercialize, the ACA or any such amendment may result in downward pressure on pharmaceutical reimbursement, which could
negatively affect market acceptance of new products. In addition, several states have not implemented the provisions of the ACA that

involve the expansion of Medicaid-eligibility for low-income adults. While the United States Supreme Court recently rejected the
latest challenge to the constitutionality of the ACA, it is possible that other legislative efforts may seek to modify it. We cannot predict
what effect any legislation may have on us or on AbbVie’s sales of MAVYRET/MAVIRET. In addition, other legislative changes
have been proposed since the Affordable Care Act was enacted. There has been increasing legislative and enforcement interest in the
United States with respect to drug pricing practices. Most recently, the Inflation Reduction Act of 2022, or IRA, which, among other
provisions, included several measures intended to lower the cost of prescription drugs and related healthcare reforms. Specifically, the
Act authorizes and directs the Department of Health and Human Services, or DHHS, to set drug price caps for certain high-cost
Medicare Part B and Part D qualified drugs, with the initial list of drugs to be selected by September 1, 2023, and the first year of
maximum price applicability to begin in calendar year 2026. The Act further authorizes the DHHS to penalize pharmaceutical
manufacturers that increase the price of certain Medicare Part B and Part D drugs faster than the rate of inflation. Finally, the Act
creates significant changes to the Medicare Part D benefit design by capping Part D beneficiaries’ annual out-of-pocket spending
beginning in calendar year 2025. We cannot be sure whether additional or related legislation or rulemaking will be issued or enacted,
or what impact, if any, such changes will have on the royalty revenue we receive from MAVYRET/MAVIRET or revenue from any
of our drug candidates, if approved for commercial use, in the future. If any further healthcare reform measures adopted in the future
result in additional downward pressure on the price that AbbVie receives for MAVYRET/MAVIRET, this would adversely affect our
future revenues, and the price of our common stock could be materially adversely affected.

Our ability to commercialize any product candidate successfully, as well as AbbVie’s continued commercialization of
MAVYRET/MAVIRET, will also depend in part on the extent to which reimbursement for these products and related treatments will
be available from government health administration authorities, private health insurers and other organizations. Government
authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which medications
they will pay for and establish reimbursement levels. A primary trend in the U.S. healthcare industry is cost containment. Government
authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular
medications. In the case of HCV, limitations of coverage have recently been used to limit access to HCV treatments for only those
patients with more advanced fibrosis. Increasingly, third-party payors are requiring that drug companies provide them with
predetermined discounts from list prices and, in many cases involving HCV drugs, seeking discounts in exchange for greater patient
access to a particular HCV drug. In addition, there are private and public payors challenging the prices charged for medical products.
We cannot be sure that reimbursement will be available for any product that we may commercialize and, if reimbursement is
available, the level of reimbursement. In addition, reimbursement may impact the demand for, or the price of, MAVYRET/MAVIRET
or any product candidate for which we may obtain marketing approval. If reimbursement is not available or is available only to limited
levels, we may not be able to successfully commercialize any product candidate for which we may seek marketing approval.

There may be significant delays in obtaining reimbursement for newly approved drugs, and coverage may be more limited than the
purposes for which the drug is approved by the FDA or comparable authorities in other jurisdictions. Moreover, eligibility for
reimbursement does not imply that any drug will be paid for in all cases or at a rate that covers our costs, including research,
development, manufacture, sale and distribution. Interim reimbursement levels for new drugs, if applicable, may also be insufficient to
cover our and any collaborator’s costs and may not be made permanent. Reimbursement rates may vary according to the use of the
drug and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost drugs and may be
incorporated into existing payments for other services. Net prices for drugs may be reduced by mandatory discounts or rebates
required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of
drugs from countries where they may be sold at lower prices than in the United States. Third-party payors often rely upon Medicare
coverage policy and payment limitations in setting their own reimbursement policies. AbbVie’s inability to continue to obtain
coverage and profitable payment rates from both government-funded and private payors for MAVYRET/MAVIRET, or our inability
to obtain the same for any product candidate that we develop, could have a material adverse effect on our operating results, our ability
to raise capital needed to commercialize products and our overall financial condition.

In general, the United States and several other jurisdictions are considering a number of legislative and regulatory proposals to change
the healthcare system in ways that could affect our ability to sell our products profitably. Among policy makers and payors in the
United States and elsewhere, there is significant interest in promoting changes in healthcare systems with the stated goals of
containing healthcare costs, improving quality and/or expanding access to healthcare. In the United States, the pharmaceutical industry
has been a particular focus of these efforts and has been significantly affected by major legislative initiatives. We expect to experience
pricing pressures in connection with the sale of any products that we develop or that are being commercialized under our collaboration
with AbbVie. The implementation of cost containment measures or other healthcare reforms may limit our ability to generate revenue,
maintain profitability or commercialize our product candidates.

Foreign governments tend to impose strict price controls, which may adversely affect our future profitability.

In most foreign countries, particularly in the European Union and Japan, prescription drug pricing and/or reimbursement is subject to
governmental control. In those countries that impose price controls, pricing negotiations with governmental authorities can take
considerable time after the receipt of marketing approval for a product. To obtain reimbursement or pricing approval in some
countries, we may be required to conduct a clinical trial that compares the cost-effectiveness of our product candidate to other
available therapies.

Some countries require approval of the sale price of a drug before it can be marketed. In many countries, the pricing review period
begins after marketing or product licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains
subject to continuing governmental control even after initial approval is granted. As a result, we (or AbbVie in the case of
MAVYRET/MAVIRET) might obtain marketing approval for a product in a particular country, but then be subject to price
regulations that delay the commercial launch of the product, possibly for lengthy time periods, and negatively impact the revenues that
are generated from the sale of the product in that country. If reimbursement of MAVYRET/MAVIRET or of any of our product
candidates is unavailable or limited in scope or amount, or if pricing is set at unsatisfactory levels, or if there is competition from
lower priced cross-border sales, our results of operations will be negatively affected.

If, in the future, we are unable to establish our own sales, marketing and distribution capabilities or enter into licensing or
collaboration agreements for these purposes, we may not be successful in commercializing any product candidates.

We do not have a sales or marketing infrastructure and have no sales, marketing or distribution experience. We will seek to either
build our own commercial infrastructure to commercialize any products if and when they are approved, or enter into licensing or
collaboration agreements where our collaborator is responsible for commercialization, as in the case of our collaboration with AbbVie,
or where we have the right to assist in the future development and commercialization of such products.

To develop internal sales, distribution and marketing capabilities, we will have to invest significant amounts of financial and
management resources, some of which will be committed prior to any confirmation that any of our proprietary product candidates will
be approved. For product candidates for which we decide to perform sales, marketing and distribution functions ourselves, we could
face a number of additional risks, including:

•

our inability to recruit 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
products;

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

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

Where and when appropriate, we may elect to utilize contract sales forces or distribution partners to assist in the commercialization of
our product candidates. If we enter into arrangements with third parties to perform sales, marketing and distribution services for our
products, the resulting revenues or the profitability from these revenues to us are likely to be lower than if we had sold, marketed and
distributed our products ourselves. In addition, we may not be successful in entering into arrangements with third parties to sell,
market and distribute our product candidates or may be unable to do so on terms that are favorable to us. We likely will have little
control over such third parties, and any of these third parties may fail to devote the necessary resources and attention to sell, market
and distribute our products effectively.

If we do not establish sales, marketing and distribution capabilities successfully, either on our own or in collaboration with third
parties, we will not be successful in commercializing our product candidates.

Commercial success of our product candidates depends upon significant market acceptance among physicians, patients and
healthcare payors of any resulting approved drug.

EDP-938 and EDP-323 and any other product candidate that we may develop in the future, whether as part of a combination therapy
or as a monotherapy, are subject to market acceptance among physicians, healthcare payors, patients and the medical community. The
degree of market acceptance of any product candidate for which we obtain approval for commercial sale, will depend on a number of
factors, including:

•

the efficacy and safety of treatment regimens containing one of our product candidates, as demonstrated in clinical trials,
and the degree to which these regimens represent a clinically meaningful improvement in care as compared with other
available therapies;

the clinical indications for which any treatment regimen containing one of our product candidates become approved;

acceptance among physicians, major operators of clinics, payors and patients of any treatment regimen containing one of
our product candidates;

the willingness of the target patient population to try new therapies and of physicians to prescribe these therapies;

the potential and perceived advantages of treatment regimens containing one of our product candidates over alternative
treatments;

•

the cost of treatment of regimens containing one of our product candidates in relation to the cost of alternative treatments;

the availability of adequate reimbursement and pricing by third parties and government authorities and successful
negotiation of favorable agreements with payors by us or any collaborator of ours, as well as the impact of any agreements
among any of the foregoing and one or more of our competitors limiting access to our product in favor of one or more
competitive products;

the continued longevity of any market for which we develop a drug;

the levels of funding provided by government-funded healthcare for treatment of any disease for which we develop a
drug;

the relative convenience and ease of administration of any treatment regimen containing one of our product candidates
compared to competitive regimens;

the prevalence and severity of adverse side effects, whether involving the use of treatment regimens containing one of our
products candidates or similar, competitive treatment regimens; and

the effectiveness of our sales and marketing efforts.

If treatment regimens containing one of our product candidates are approved and then fail to achieve market acceptance, we may not
be able to generate significant additional revenue. Further, if new, more favorably received therapies are introduced after any such
regimen achieves market acceptance, then we may not be able to maintain that market acceptance over time.

Risks Related to Our Dependence on Third Parties

We may not be successful in establishing new product collaborations, which could adversely affect our ability to develop and
commercialize one or more of our product candidates. If we are unsuccessful in maintaining or forming alliances on favorable
terms, our business may not succeed.

We may seek to enter into additional product collaborations in the future, including alliances with other biotechnology or
pharmaceutical companies, to enhance and accelerate the development and commercialization of one or more of our product
candidates. For example, we plan to out-license our FXR agonist candidates for combination therapy for NASH and are seeking
potential partners for this program. We face significant competition in seeking appropriate collaborators and the negotiation process is
time-consuming and complex. Moreover, we may not be successful in our efforts to establish other product collaborations or other
alternative arrangements for any product candidates and programs because our research and development pipeline may be insufficient,
our product candidates and programs may be deemed to be at too early of a stage of development for collaborative effort and/or third
parties may not view our product candidates and programs as having the requisite potential to demonstrate safety and efficacy. Even if
we are successful in our efforts to establish product collaborations, the terms that we agree upon may not be favorable to us and we
may not be able to maintain such product collaborations if, for example, development or approval of a product candidate is delayed or
sales of an approved product are disappointing.

If our existing collaboration agreement with AbbVie is terminated, or if we determine that entering into other product collaborations is
in our best interest but we either fail to enter into, experience a delay in entering into, or fail to maintain, such collaborations:

•

the development of certain of our product candidates may be terminated or delayed;

our cash expenditures related to the development of certain of our product candidates would increase significantly and we
may need to seek additional financing;

we may be required to hire additional employees or otherwise develop expertise, such as clinical, regulatory, sales and
marketing expertise, which we do not currently have;

we will bear all of the risk related to the development of any such product candidates; and

the competitiveness of any product candidate that is commercialized could be reduced.

We intend to rely on third-party manufacturers to produce our development-stage product candidate supplies and any commercial
supplies of any approved product candidates. Any failure by a third-party manufacturer to produce acceptable supplies for us may
delay or impair our ability to initiate or complete our clinical trials or sell any resulting product.

We do not currently own or operate any manufacturing facilities. We plan to continue to work with third-party contract manufacturers
to produce sufficient quantities of any product candidates for preclinical testing, clinical trials and commercialization. If we are unable
to arrange for such a third-party manufacturing source for any of our product candidates, or fail to do so on commercially reasonable

terms, we may not be able to successfully produce, develop and market one or more of our product candidates, or we may be delayed
in doing so.

Reliance on third-party manufacturers entails risks to which we would not be subject if we manufactured product candidates
ourselves, including reliance on the third party for regulatory compliance and quality control and assurance, volume production, the
possibility of breach of the manufacturing agreement by the third party because of factors beyond our control (including a failure to
synthesize and manufacture our product candidates in accordance with our product specifications), shutdowns of manufacturing sites
or other supply chain constraints, and the possibility of termination or nonrenewal of the agreement by the third party at a time that is
costly or damaging to us. In addition, the FDA and other regulatory authorities require that our product candidates be manufactured
according to cGMP and similar foreign standards. Pharmaceutical manufacturers and their subcontractors are required to register their
facilities and/or products manufactured at the time of submission of the marketing application and then annually thereafter with the
FDA and certain state and foreign agencies. They are also subject to periodic unannounced inspections by the FDA, state and other
foreign authorities. Any subsequent discovery of problems with a product, or a manufacturing or laboratory facility used by us or our
collaborators, may result in restrictions on the product or on the manufacturing or laboratory facility, including marketed product
recall, suspension of manufacturing, product seizure, or a voluntary withdrawal of the drug from the market. Any failure by our third-
party manufacturers to comply with cGMP or failure to scale up manufacturing processes, including any failure to deliver sufficient
quantities of product candidates in a timely manner, could lead to a delay in, or failure to obtain, regulatory approval of any of our
product candidates.

We plan to rely on third-party manufacturers to purchase from third-party suppliers the materials necessary to produce our product
candidates for our clinical studies. There are a small number of suppliers for certain capital equipment and materials that we plan to
use to manufacture our drugs. Such suppliers may not sell these materials to our manufacturers at the times we need them or on
commercially reasonable terms. Moreover, we currently do not have any agreements for the production of these materials. Although
we do not intend to begin a clinical trial unless we believe we have a sufficient supply of a product candidate to complete the clinical
trial, any significant delay in the supply of a product candidate or the material components thereof for an ongoing clinical trial due to
the need to replace a third-party manufacturer could considerably delay completion of our clinical studies, product testing and
potential regulatory approval of our product candidates. If our manufacturers or we are unable to purchase these materials 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 revenue from the sale of our product candidates.

Contract manufacturers may not be able to manufacture our product candidates at a cost or in quantities or in a timely manner
necessary to develop and commercialize them. If we successfully commercialize any of our product candidates, to meet our projected
needs we may need to find third parties that will increase their scale of production, or we may have to establish or access large-scale
commercial manufacturing capabilities. We may require additional funds, personnel and other resources to build, lease or operate any
manufacturing facility.

A portion of our research and a portion of our manufacturing of certain key intermediates used in the manufacture of the active
pharmaceutical ingredients for our product candidates takes place in China through third-party researchers and manufacturers. A
significant disruption in the operation of those researchers or manufacturers, or a trade war, geopolitical unrest or an epidemic in
China, such as the COVID-19 pandemic, could materially adversely affect our business, financial condition and results of
operations.

Although manufacturing for MAVYRET/MAVIRET is being conducted by AbbVie, we have relied on third parties located in China
to manufacture and supply certain key intermediates used in the manufacture of our active pharmaceutical ingredients, or API, for our
current product candidates, and we expect to continue to use such third party manufacturers for such intermediates for any product
candidates we develop independently. Any disruption in production or inability of our manufacturers in China to produce adequate
quantities to meet our needs, whether as a result of a natural disaster, pandemics or other causes, could impair our ability to operate
our business on a day-to-day basis and to continue our research and development of our product candidates. We also use contract
researchers in China to conduct a portion of our research for our early-stage programs. Any disruption in the team conducting that
research could cause delays in one or more of our research programs and could require us to curtail one or more programs, at least
until we could contract for that research to be done elsewhere. For example, either of these risks could be triggered by an epidemic
such as the outbreak of COVID-19 in the Wuhan region of China or the series of so-called “lock-downs” in China when strict
quarantine requirements were imposed on large population areas in response to new incidents of COVID infection. Our contract
manufacturers in China, which are not located in the Wuhan region, managed to avoid any material delays in their ability to deliver
API and other services through extraordinary efforts, including temporarily housing staff in the manufacturing facility. Furthermore,
since these researchers and manufacturers are located in China, we are exposed to the possibility of product supply disruption and
increased costs in the event of changes in the policies of the United States or Chinese governments, geopolitical unrest or unstable
economic conditions in China. For example, a trade war could lead to tariffs on the chemical intermediates we use that are
manufactured in China. Any of these matters could materially and adversely affect our business and results of operations. Any recall
of the manufacturing lots or similar action regarding our API used in clinical trials could delay the trials or detract from the integrity

of the trial data and its potential use in future regulatory filings. In addition, manufacturing interruptions or failure to comply with
regulatory requirements by any of these manufacturers could significantly delay clinical development of potential products and reduce
third-party or clinical researcher interest and support of proposed trials. These interruptions or failures could also impede
commercialization of our product candidates and impair our competitive position. Further, we may be exposed to fluctuations in the
value of the local currency in China. Future appreciation of the local currency could increase our costs. In addition, our labor costs
could continue to rise as wage rates increase due to increased demand for skilled laborers and the availability of skilled labor declines
in China.

We will rely on third parties to monitor, support, conduct and/or oversee clinical trials of our product candidates that we develop
independently and, in some cases, to maintain regulatory files for those product candidates. If we are not able to maintain or
secure agreements with such third parties on acceptable terms, if these third parties do not perform their services as required, if
geopolitical unrest disrupts activity at a number of our clinical trial sites, or if these third parties fail to timely transfer any
regulatory information held by them to us, we may not be able to conduct our clinical trials in a timely manner, obtain regulatory
approval for, or commercialize, our product candidates.

We will rely on CROs, hospitals, clinics, academic institutions and other third-party collaborators who are outside our control to
monitor, support, conduct and/or oversee preclinical and clinical studies of our product candidates. We will also rely on third parties to
perform clinical trials of our product candidates when they reach that stage. As a result, we have less control over the timing and cost
of these studies and the ability to recruit trial subjects than if we conducted these trials wholly by ourselves. If we are unable to
maintain or enter into agreements with these third parties on acceptable terms or engagement is terminated, we may be unable to enroll
patients on a timely basis or otherwise conduct our trials in the manner we anticipate. Additionally, although no situations to date have
caused a significant disruption in our clinical trial operations, geopolitical unrest or a pandemic, could disrupt a number of our clinical
trial sites and cause one or more of our clinical trials to be delayed. In the case of EDP-938, we paused recruitment and dosing as a
result of the COVID-19 pandemic in March 2020, but we were able to resume the studies in July 2020. The pause in these studies, as
well as the absence of RSV in the population generally, delayed enrollment of these studies, and it is uncertain whether any of our
other ongoing studies may be subject to further disruptions. In addition, there is no guarantee that these third parties will devote
adequate time and resources to our studies or perform as required by a contract or in accordance with regulatory requirements,
including maintenance of clinical trial information regarding our product candidates. If these third parties fail to meet expected
deadlines, fail to timely transfer to us any regulatory information, fail to adhere to protocols or fail to act in accordance with regulatory
requirements or our agreements with them, or if they otherwise perform in a substandard manner or in a way that compromises the
quality or accuracy of their activities or the data they obtain, then clinical trials of our product candidates may be extended, delayed or
terminated, or our data may be rejected by the FDA or regulatory agencies.

To the extent we elect to enter into additional licensing or collaboration agreements to partner our product candidates, our
dependence on such relationships may adversely affect our business.

Our commercialization strategy for some of our product candidates may depend on our ability to enter into collaboration agreements
with other companies to obtain access to other compounds for use in combination with any of our product candidates or for assistance
and funding for the development and potential commercialization of any of these product candidates, similar to what we have done
with AbbVie. Supporting diligence activities conducted by potential collaborators and negotiating the financial and other terms of a
collaboration agreement are long and complex processes with uncertain results. Even if we are successful in entering into one or more
additional collaboration agreements, collaborations can involve greater uncertainty for us, as we may have limited or no control over
certain aspects of our collaborative programs. We may determine that continuing a collaboration under the terms provided is not in our
best interest, and we may terminate the collaboration. Our collaborators could delay or terminate their agreements with us, and our
product candidates subject to collaborative arrangements may never be successfully commercialized.

Further, our collaborators may develop alternative products or pursue alternative technologies either on their own or in collaboration
with others, including our competitors, and the priorities or focus of our collaborators may shift such that our programs receive less
attention or resources than we would like, or they may be terminated altogether. Any such actions by our collaborators may adversely
affect our business prospects and ability to earn revenue. In addition, we could have disputes with our collaborators, such as the
interpretation of terms in our agreements. Any such disagreements could lead to delays in the development or commercialization of
any potential products or could result in time-consuming and expensive litigation or arbitration, which may not be resolved in our
favor.

Even with respect to programs that we intend to commercialize ourselves, we may enter into agreements with collaborators to share in
the burden of conducting clinical trials, manufacturing and marketing our product candidates or products. In addition, our ability to
apply our proprietary technologies to develop proprietary compounds will depend on our ability to establish and maintain licensing
arrangements or other collaborative arrangements with the holders of proprietary rights to such compounds. We may not be able to
establish such arrangements on favorable terms or at all, and our collaborative arrangements may not be successful.

Risks Related to Our Intellectual Property Rights

We are competing to develop intellectual property in areas of small-molecule drug development that are highly competitive. We
could be unsuccessful in obtaining or maintaining adequate patent protection for one or more of our product candidates.

Our commercial success will depend, in large part, on our ability to obtain and maintain patent and other intellectual property
protection with respect to our product candidates. We cannot be certain that patents will be issued or granted with respect to our patent
applications that are currently pending, or that issued or granted patents will not later be found to be invalid and/or unenforceable, be
interpreted in a manner that does not adequately protect our products, or otherwise provide us with any competitive advantage. The
patent position of biotechnology and pharmaceutical companies is generally uncertain because it involves complex legal and factual
considerations. The standards applied by the United States Patent and Trademark Office and foreign patent offices in granting patents
are not always applied uniformly or predictably. For example, there is no uniform worldwide policy regarding patentable subject
matter or the scope of claims allowable in biotechnology and pharmaceutical patents. Consequently, patents may not issue from our
pending patent applications. As such, we do not know the degree of future protection that we will have on our proprietary products
and technology, if any, and a failure to obtain adequate intellectual property protection with respect to our product candidates and
proprietary technology could have a material adverse impact on our business.

In addition, certain of our activities in the past have been funded, and others may in the future be funded, by the United States federal
government. For example, the preclinical and early clinical development of the lead antibiotic product candidate in our former
antibiotic program, which we are no longer developing, was funded under a contract with NIAID, an entity of the United States
federal government. When new technologies are developed with United States federal government funding, the government obtains
certain rights in any resulting patents, including a nonexclusive license authorizing the government to use the invention for non-
commercial purposes. These rights may permit the government to disclose our confidential information to third parties and to exercise
“march-in” rights to use or allow third parties to use our patented technology. The government can exercise its march-in rights if it
determines that action is necessary because we fail to achieve practical application of the United States government-funded
technology, or because action is necessary to alleviate health or safety needs, to meet requirements of federal regulations or to give
preference to United States industry. In addition, United States government-funded inventions must be reported to the government and
United States government funding must be disclosed in any resulting patent applications. In addition, our rights in such inventions are
subject to certain requirements to manufacture products in the United States.

Claims that our product candidates or the sale or use of our products infringe the patent or other intellectual property rights of
third parties could result in costly litigation or could require substantial time and money to resolve, even if litigation is avoided.

Our commercial success depends upon our ability to develop, manufacture, market and sell our product candidates and use our
proprietary technology without infringing the intellectual property rights of others. We cannot guarantee that our product candidates or
any uses of our product candidates do not and will not in the future infringe third-party patents or other intellectual property rights.
Third parties might allege that we or our collaborators are infringing their patent rights or that we have misappropriated their trade
secrets, or that we are otherwise violating their intellectual property rights, whether with respect to the manner in which we have
conducted our research or to the composition, use or manufacture of the compounds we have developed or are developing with our
collaborators. Such third parties might resort to litigation against us or other parties we have agreed to indemnify, which litigation
could be based on either existing intellectual property or intellectual property that arises in the future.

It is also possible that we failed to identify, or may in the future fail to identify, relevant patents or patent applications held by third
parties that cover our product candidates. For example, applications filed before November 29, 2000 and certain applications filed
after that date that will not be filed outside the United States remain confidential until patents issue. Other patent applications in
the United States and several other jurisdictions are published approximately 18 months after the earliest filing for which priority is
claimed, with such earliest filing date being commonly referred to as the priority date. Furthermore, publication of discoveries in the
scientific or patent literature often lags behind actual discoveries. Therefore, we cannot be certain that we or our collaborators were the
first to invent, or the first to file patent applications on, our product candidates or for their uses, or that our product candidates will not
infringe patents that are currently issued or that are issued in the future. In the event that a third party has also filed a patent application
covering one of our product candidates or a similar invention, we may have to participate in an adversarial proceeding, known as an
interference, declared by the U.S. Patent and Trademark Office or its foreign counterpart to determine priority of invention.
Additionally, pending patent applications which have been published can, subject to certain limitations, be later amended in a manner
that could cover our products or their use.

In order to avoid or settle potential claims with respect to any patent or other intellectual property rights of third parties, we may
choose or be required to seek a license from a third party and be required to pay license fees or royalties or both, which could be
substantial. These licenses may not be available on acceptable terms, or at all. Even if we were able to obtain a license, the rights may
be nonexclusive, which could result in our competitors gaining access to the same intellectual property. Ultimately, we could be
prevented from commercializing a product, or be forced, by court order or otherwise, to cease some or all aspects of our business
operations, if, as a result of actual or threatened patent or other intellectual property claims, we are unable to enter into licenses on

acceptable terms. Further, we could be found liable for significant monetary damages as a result of claims of intellectual property
infringement. For example, we have received, and may in the future receive, offers to license and demands to license from third
parties claiming that we are infringing their intellectual property or owe license fees and, even if such claims are without merit, there
can be no assurance that we will successfully avoid or settle such claims.

In addition, if AbbVie licenses or otherwise acquires rights to intellectual property controlled by a third party in various
circumstances, for example, where a product could not be legally developed or commercialized in a country without the third-party
intellectual property right, it is entitled under our collaboration agreement to decrease payments payable to us on a product-by-product
basis and, in certain cases, on a country-by-country basis. Any of the foregoing events could harm our business significantly.
Defending against claims of patent infringement, misappropriation of trade secrets or other violations of intellectual property rights
could be costly and time consuming, regardless of the outcome. Thus, even if we were to ultimately prevail, or to settle at an early
stage, such litigation could burden us with substantial unanticipated costs. In addition, litigation or threatened litigation could result in
significant demands on the time and attention of our management team, distracting them from the pursuit of other company business.
Claims that our product candidates or the sale or use of our future products infringe, misappropriate or otherwise violate third-party
intellectual property rights could therefore have a material adverse impact on our business.

Issued patents covering one or more of our product candidates could be found invalid or unenforceable if challenged in court.

Despite measures we take to obtain patent and other intellectual property protection with respect to our product candidates and
proprietary technology, any of our intellectual property rights could be challenged or invalidated. For example, if we were to initiate
legal proceedings against a third party to enforce a patent covering one of our product candidates, the defendant could counterclaim
that our patent is invalid and/or unenforceable. The same could occur in our patent infringement suit recently brought against Pfizer
regarding Paxlovid, its antiviral treatment for COVID-19, even though our ‘953 patent at issue does not cover EDP-235. In patent
litigation in the United States and in some other jurisdictions, defendant counterclaims alleging invalidity and/or unenforceability are
commonplace. Grounds for a validity challenge could be an alleged failure to meet any of several statutory requirements, for example,
lack of novelty, obviousness or non-enablement. Grounds for an unenforceability assertion could be an allegation that someone
connected with prosecution of the patent withheld relevant information from the United States Patent and Trademark Office, or the
applicable foreign counterpart, or made a misleading statement, during prosecution. Although we believe that we have conducted our
patent prosecution in accordance with the duty of candor and in good faith, the outcome following legal assertions of invalidity and
unenforceability during patent litigation is unpredictable. With respect to the validity question, for example, we cannot be certain that
there is no invalidating prior art, of which we and the patent examiner were unaware during prosecution. If a defendant were to prevail
on a legal assertion of invalidity and/or unenforceability, we would lose at least part, and perhaps all, of the patent protection on a
product candidate. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, other than in litigation like
the Pfizer case, we would lose at least part, and perhaps all, of the patent protection on a product candidate. Even if a defendant does
not prevail on a legal assertion of invalidity and/or unenforceability, our patent claims may be construed in a manner that would limit
our ability to enforce such claims against the defendant and others. Any loss of patent protection could have a material adverse impact
on one or more of our product candidates and our business.

Enforcing our intellectual property rights against third parties may also cause such third parties to file other counterclaims against us,
which could be costly to defend and could require us to pay substantial damages, cease the sale of certain products or enter into a
license agreement and pay royalties (which may not be possible on commercially reasonable terms or at all). Any efforts to enforce
our intellectual property rights are also likely to be costly and may divert the efforts of our scientific and management personnel. Any
efforts to enforce our intellectual property rights are also likely to be costly, as may well be the case with the Pfizer suit, and may
divert the efforts of our scientific and management personnel.

Intellectual property litigation may lead to unfavorable publicity that harms our reputation and causes the market price of our
common stock to decline.

During the course of any intellectual property litigation, there could be public announcements of the results of hearings, rulings on
motions, and other interim proceedings in the litigation. If securities analysts or investors regard these announcements as negative, the
perceived value of our products, programs or intellectual property could be diminished. Accordingly, the market price of our common
stock may decline. Such announcements could also harm our reputation or the market for our future products, which could have a
material adverse effect on our business.

Intellectual property rights do not necessarily protect us from all potential threats to our competitive advantage.

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

•

others may be able to make compounds that are similar to our product candidates but that are not covered by the claims of
the patents that we own or have exclusively licensed;

we might not have been the first to make the inventions covered by the issued patents or pending patent applications that
we own or may in the future exclusively license, which could result in the patent applications not issuing or being
invalidated after issuing;

we might not have been the first to file patent applications covering certain of our inventions, which could result in the
patent applications not issuing or being invalidated after issuing;

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

it is possible that our pending patent applications will not lead to issued patents;

issued patents that we own may not provide us with any competitive advantages, or may be held invalid or unenforceable,
as a result of legal challenges by our competitors; we may obtain patents for certain compounds many years before we
obtain marketing approval for products containing such compounds, and because patents have a limited life, which may
begin to run prior to the commercial sale of the related product, the commercial value of our patents may be limited;

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

we may fail to develop additional proprietary technologies that are patentable;

the laws of certain foreign countries may not protect our intellectual property rights to the same extent as the laws of
the United States, or we may fail to apply for or obtain adequate intellectual property protection in all the jurisdictions in
which we operate; and

the patents of others may have an adverse effect on our business, for example, by preventing us from marketing one or
more of our product candidates for one or more indications.

Any of the aforementioned threats to our competitive advantage could have a material adverse effect on our business.

Unfavorable outcomes in intellectual property litigation could limit our research and development activities and/or our ability to
commercialize certain products.

If third parties successfully assert their intellectual property rights against us, we might be barred from using certain aspects of our
technology or barred from developing and commercializing certain products. Prohibitions against using certain technologies, or
prohibitions against commercializing certain products, could be imposed by a court or by a settlement agreement between us and a
plaintiff. In addition, if we are unsuccessful in defending against allegations that we have infringed, misappropriated or otherwise
violated patent or other intellectual property rights of others, we may be forced to pay substantial damage awards to the plaintiff.
There is inevitable uncertainty in any litigation, including intellectual property litigation. There can be no assurance that we would
prevail in any intellectual property litigation, even if the case against us is weak or flawed. If litigation leads to an outcome
unfavorable to us, we may be required to obtain a license from the intellectual property owner to continue our research and
development programs or to market any resulting product. It is possible that the necessary license will not be available to us on
commercially acceptable terms, or at all. Alternatively, we may be required to modify or redesign our products to avoid infringing or
otherwise violating third-party intellectual property rights. This may not be technically or commercially feasible, may render our
products less competitive, or may delay or prevent the entry of our products to the market. Any of the foregoing could limit our
research and development activities, our ability to commercialize one or more product candidates, or both.

Most of our competitors are larger than we are and have substantially greater resources. They are, therefore, likely to be able to sustain
the costs of complex intellectual property litigation longer than we could. In addition, the uncertainties associated with litigation could
have a material adverse effect on our ability to raise the funds necessary to conduct our clinical trials, continue our internal research
programs, in-license needed technology, or enter into strategic partnerships that would help us bring our product candidates to market.
In addition, any future intellectual property litigation, interference or other administrative proceedings will result in additional expense
and distraction of our personnel. An adverse outcome in such litigation or proceedings may expose us or any future strategic partners
to loss of our proprietary position, expose us to significant liabilities, or require us to seek licenses that may not be available on
commercially acceptable terms, if at all, each of which could have a material adverse effect on our business.

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

In addition to patents, we rely on trade secrets, technical know-how and proprietary information concerning our business strategy and
product candidates to protect our competitive position in the field of each of our antiviral product candidates and our NASH
compounds. In the course of our research and development activities and our business activities, we often rely on confidentiality
agreements to protect our proprietary information. Such confidentiality agreements are used, for example, when we talk to vendors of
laboratory or clinical development services or potential strategic partners. In addition, each of our employees is required to sign a
confidentiality agreement and invention assignment agreement upon joining our company. We take steps to protect our proprietary
information, and our confidentiality agreements and invention assignment agreements are carefully drafted to protect our proprietary
interests. Nevertheless, there can be no guarantee that an employee or an outside party will not make an unauthorized disclosure of our
proprietary confidential information. This might happen intentionally or inadvertently. It is possible that a competitor will make use of
such information, and that our competitive position will be compromised, in spite of any legal action we might take against persons
making such unauthorized disclosures. In addition, to the extent that our employees, consultants or contractors use intellectual
property owned by others in their work for us, disputes may arise as to the rights in related or resulting know-how and inventions.
Trade secrets are difficult to protect. Although we use reasonable efforts to protect our trade secrets, our employees, consultants,
contractors, business partners or outside scientific collaborators might intentionally or inadvertently disclose our trade secret
information to competitors or our trade secrets may otherwise be misappropriated. Enforcing a claim that a third party illegally
obtained and is using any of our trade secrets is expensive and time consuming, and the outcome is unpredictable. In addition, courts
outside the United States sometimes are less willing than United States courts to protect trade secrets. Moreover, our competitors may
independently develop equivalent knowledge, methods and know-how.

Our collaborators may have rights to publish data and other information to which we have rights. In addition, we sometimes engage
individuals or entities to conduct research relevant to our business. The ability of these individuals or entities to publish or otherwise
publicly disclose data and other information generated during the course of their research is subject to certain contractual limitations.
These contractual provisions may be insufficient or inadequate to protect our confidential information. If we do not apply for patent
protection prior to such publication, or if we cannot otherwise maintain the confidentiality of our proprietary technology and other
confidential information, then our ability to obtain patent protection or to protect our trade secret information may be jeopardized,
which could adversely affect our business.

Changes in patent law could diminish the value of patents in general, thereby impairing our ability to protect our products.

As is the case with many other biopharmaceutical companies, our success is heavily dependent on intellectual property, particularly
patents. Obtaining, maintaining and enforcing patents in the biopharmaceutical industry involves both technological complexity and
legal complexity. Therefore, the process of obtaining, maintaining and enforcing biopharmaceutical patents is costly, time-consuming
and inherently uncertain. In addition, recent legislative and judicial developments in the United States and elsewhere have in some
cases narrowed the protection afforded to patent owners, made patents more difficult to obtain, or increased the uncertainty regarding
the ability to obtain, maintain and enforce patents. For example, Congress recently passed patent reform legislation, and may pass
patent reform legislation in the future. The United States Supreme Court has ruled on several patent cases in recent years, and in
certain circumstances has narrowed the scope of patent protection available or otherwise weakened the rights of patent owners. In
addition to increasing uncertainty with regard to our ability to obtain patents in the future, this combination of events has created
uncertainty with respect to the value of patents, once obtained. Depending on decisions and actions by the United States Congress, the
federal courts, the United States Patent and Trademark Office, and their respective foreign counterparts, the laws and regulations
governing patents could change in unpredictable ways that could weaken our ability to obtain new patents or to maintain and enforce
our existing patents and patents that we might obtain in the future.

Risks Related to Our Industry

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

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

Regardless of the merits or eventual outcome, liability claims may result in:

•

decreased demand for our product candidates or any resulting products;

injury to our reputation;

withdrawal of clinical trial participants;

costs to defend the related litigation;

a diversion of management’s time and our resources;

substantial monetary awards to trial participants or patients;

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

loss of revenue;

the inability to commercialize our product candidates; and

a decline in our stock price.

Our inability to obtain and retain sufficient product liability insurance at an acceptable cost to protect against potential product liability
claims could prevent or inhibit the commercialization of products we develop. We currently carry product liability insurance covering
our clinical studies in the amount of $15.0 million in the aggregate. Although we maintain such insurance, any claim that may be
brought against us could result in a court judgment or settlement in an amount that is not covered, in whole or in part, by our insurance
or that is in excess of the limits of our insurance coverage. Our insurance policies also have various exclusions, and we may be subject
to a product liability claim for which we have no coverage. We will have to pay any amounts awarded by a court or negotiated in a
settlement that exceed our coverage limitations or that are not covered by our insurance, and we may not have, or be able to obtain,
sufficient capital to pay such amounts.

Our internal computer systems, or those of our collaborator, CROs or other contractors or consultants, may fail or suffer security
breaches, which could result in a material disruption of development programs for our product candidates.

Despite the implementation of security measures, our internal computer systems and those of our collaborators, CROs, and other
contractors and consultants are vulnerable to damage from computer viruses, unauthorized access, natural disasters, pandemics,
terrorism, war and telecommunication and electrical failures. Information security risks have significantly increased in recent years
and during the COVID-19 pandemic in part due to the proliferation of new technologies, the increased sophistication and activities of
organized crime, hackers, terrorists and other external parties, including foreign state actors as well as remote working for many
businesses. As cyber threats continue to evolve, we may be required to expend significant additional resources to continue to modify
or enhance our protective measures or to investigate and remediate any information security breaches.

While we have not experienced any such system failure, accident or security breach to date, if such an event were to occur and cause
interruptions in our operations, it could result in a material disruption of our independent drug development programs. For example,
the loss of clinical trial data from ongoing or future clinical trials for any of our product candidates could result in delays in regulatory
approval efforts and significantly increase costs to recover or reproduce the data. Our information security systems are also subject to
laws and regulations requiring that we take measures to protect the privacy and security of certain information we gather and use in
our business. For example, HIPAA and its implementing regulations impose, among other requirements, certain regulatory and
contractual requirements regarding the privacy and security of personal health information. In the European Union, the General Data
Protection Regulation, or GDPR, is even more restrictive with respect to all personal information, including information masked by a
coding system. In addition to HIPAA and GDPR, numerous other federal and state laws, including, without limitation, state security
breach notification laws, state health information privacy laws and federal and state consumer protection laws, govern the collection,
use, disclosure and storage of personal information. To the extent that any disruption or security breach were to result in a loss of or
damage to data or applications, or inappropriate disclosure of confidential or proprietary information or personal health information,
we could incur substantial liability, our reputation would be damaged, and the further development of our product candidates could be
delayed.

Our relationships with customers and third-party payors in the United States and elsewhere will be subject to applicable anti-
kickback, fraud and abuse and other healthcare laws and regulations, which could expose us to criminal sanctions, civil penalties,
contractual damages, reputational harm and diminished profits and future earnings.

Healthcare providers, physicians and third-party payors in the United States and elsewhere 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 that may constrain the

business or financial arrangements and relationships through which we market, sell and distribute our products for which we obtain
marketing approval. Restrictions under applicable federal, state and foreign healthcare laws and regulations include the following:

•

the federal healthcare anti-kickback statute 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 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;

the federal False Claims Act imposes 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, 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, as amended by the Health Information
Technology for Economic and Clinical Health Act, imposes criminal and civil liability for executing a scheme to defraud
any healthcare benefit program and also imposes obligations, including mandatory contractual terms, with respect to
safeguarding the privacy, security and transmission of individually identifiable health information;

the federal false statements statute prohibits knowingly and willfully falsifying, concealing or covering up a material fact
or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or
services;

the federal transparency requirements under the Patient Protection and Affordable Care Act of 2010 require manufacturers
of drugs, devices, biologics and medical supplies to report to the Department of Health and Human Services information
related to physician payments and other transfers of value and physician ownership and investment interests;

analogous state laws and regulations, such as state anti-kickback and false claims laws, may apply to sales or marketing
arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payors,
including private insurers, and some state laws require pharmaceutical companies to comply with the pharmaceutical
industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government
in addition to requiring drug manufacturers to report information related to payments to physicians and other healthcare
providers or marketing expenditures; and

•

analogous anti-kickback, fraud and abuse and healthcare laws and regulations in foreign countries.

Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations will
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, damages, fines, exclusion from government funded 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 providers or entities with whom we expect to do business, including our
collaborators, are found not to be in compliance with applicable laws, they may be subject to criminal, civil or administrative
sanctions, including exclusions from government funded healthcare programs, which could also materially affect our business.

Risks Related to Our Common Stock

Our stock price has been, and is likely to continue to be, volatile, and thus our stockholders could incur substantial losses.

Our stock price has been volatile and could be subject to wide fluctuations in response to various factors, many of which are beyond
our control. From October 1, 2018 through September 30, 2023, the daily closing price of our common stock on the NASDAQ Global
Select Market has ranged from $11.09 to $105.66. The stock market in general and the market for biopharmaceutical companies, and
for those developing potential therapies for viral infections in particular, have experienced extreme volatility that has often been
unrelated to the operating performance of particular companies. As a result of this volatility, you may not be able to sell your holdings
of our common stock at or above your purchase price, if at all. The market price for our common stock may be influenced by many
factors, including:

•

results from or delays of clinical trials of our product candidates, as well as results of regulatory reviews relating to the
approval of our product candidates;

the results of our efforts to discover or develop additional product candidates;

new products, product candidates or new uses for existing products or technologies introduced or announced by our
competitors and the timing of these introductions or announcements;

•

market expectations about and response to the levels of sales or scripts achieved by, or the announced prices or discounts
for, AbbVie’s MAVYRET/MAVIRET regimen or competitive HCV drugs;

failure of AbbVie’s MAVYRET/MAVIRET regimen to maintain its sales levels;

our dependence on third parties, including our collaborators, CROs, manufacturers, clinical trial sponsors and clinical
investigators;

regulatory, political or legal developments in the United States or other countries;

developments or disputes concerning patent applications, issued patents or other proprietary rights;

the recruitment or departure of key scientific or management personnel;

our ability to commercialize our product candidates we develop independently, if approved;

the level of expenses related to any of our product candidates or clinical development programs;

actual or anticipated changes in estimates as to financial results, development timelines or recommendations by securities
analysts;

period-to-period variations in our financial results or those of companies that are perceived to be similar to us;

market conditions in the pharmaceutical and biotechnology sectors;

sales of common stock by us or our stockholders in the future, as well as the overall trading volume of our common stock;

changes in the structure of healthcare payment systems or other actions that affect the effective reimbursement rates for
treatment regimens containing our products or for competitive regimens;

general economic, industry and market conditions and other factors that may be unrelated to our operating performance or
the operating performance of our competitors, including changes in market valuations of similar companies; and

the other factors described in this “Risk Factors” section.

A sale of a substantial number of shares of our common stock in the public market could cause the market price of our common
stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. These sales, or the
perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our
common stock. As of September 30, 2023 we had 21.1 million shares of common stock outstanding. In addition, as of September 30,
2023, we had 4.4 million and 0.6 million shares of common stock that are subject to outstanding options and restricted stock unit
awards, respectively, under our outstanding equity plans eligible for sale in the public market to the extent permitted by the provisions
of various vesting schedules, and Rule 144 under the Securities Act. If these additional shares of common stock are sold, or it is
perceived that they will be sold, in the public market, the trading price of our common stock could decline.

If securities or industry analysts do not publish research, or publish inaccurate or unfavorable research about our business, our
stock price and trading volume would likely decline.

The trading market for our common stock will depend in part on the research and reports that securities or industry analysts publish
about us or our business. For example, when those analysts are unable to predict accurately the demand and net sales of AbbVie’s
HCV regimens, our reported revenues have often been lower than the so-called “market consensus” of our projected revenues, which
has at times negatively affected our stock price. When one or more of the analysts who cover us downgrades our stock or publishes
inaccurate or unfavorable research about our business, our stock price has declined. If one or more of these analysts cease coverage of
our company or fail to publish reports on us regularly, demand for our stock could decrease, which might cause our stock price and
trading volume to decline. In addition, if too few securities or industry analysts cover our company, the trading price for our stock
would likely be negatively impacted.

Provisions in our corporate charter documents and under Delaware law could make an acquisition of us, which may be beneficial
to our stockholders, more difficult and may prevent attempts by our stockholders to replace or remove our current management.

Provisions in our corporate charter and our bylaws may discourage, delay or prevent a merger, acquisition or other change in control
of us that stockholders may consider favorable, including transactions in which they might otherwise receive a premium for their
shares.

These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby
depressing the market price of our common stock. In addition, because our board of directors is responsible for appointing the
members of our management team, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove
our current management by making it more difficult for stockholders to replace members of our board of directors. Among other
things, these provisions:

•

establish a classified or staggered board of directors such that not all members of the board are elected at one time;

allow the authorized number of our directors to be changed only by resolution of our board of directors;

limit the manner in which stockholders can remove directors from the board;

establish advance notice requirements for stockholder proposals that can be acted on at stockholder meetings and
nominations to our board of directors;

require that stockholder actions must be effected at a duly called stockholder meeting and prohibit actions by our
stockholders by written consent;

limit who may call stockholder meetings;

provide that the state courts or, in certain circumstances, the federal courts, in Delaware shall be the sole and exclusive
forum for certain actions involving us, our directors, officers, employees and stockholders;

provide our board of directors with the authority to designate the terms of and issue a new series of preferred stock
without stockholder approval, which could be used to institute a “poison pill” that would work to dilute the stock
ownership of a potential hostile acquirer, effectively preventing acquisitions that have not been approved by our board of
directors; and

require the approval of the holders of at least 66 2/3% of the votes that all our stockholders would be entitled to cast to
amend or repeal certain provisions of our charter or bylaws.

Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General
Corporation Law, which prohibit a person who owns 15% or more of our outstanding voting stock from merging or combining with us
for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting
stock, unless the merger or combination is approved in a prescribed manner. Any provision in our corporate charter or our bylaws or
Delaware law that has the effect of delaying or deterring a change in control could limit the opportunity for our stockholders to receive
a premium for their shares of our common stock and could also affect the price that some investors are willing to pay for our common
stock.

Our employment agreements with our executive officers may require us to pay severance benefits to any of those persons who are
terminated in connection with a change of control of us, which could harm our financial condition or results.

Our executive officers are parties to employment agreements that provide for aggregate cash payments of up to approximately $6.2
million for severance and other non-equity-based benefits in the event of a termination of employment in connection with a change of
control of our company. The payment of these severance benefits could harm our company’s financial condition and results. In
addition, these potential severance payments may discourage or prevent third parties from seeking a business combination with us.

Because we do not anticipate paying cash dividends on our common stock for the foreseeable future, investors in our common
stock may never receive a return on their investment.

You should not rely on an investment in our common stock to provide dividend income. We do not anticipate that we will pay any
cash dividends to holders of our common stock for the foreseeable future. Instead, we plan to retain any earnings to maintain and
expand our existing operations.

Accordingly, investors must rely on sales of their common stock after price appreciation, which may never occur, as the only way to
realize any return on their investment. As a result, investors seeking cash dividends should not invest in our common stock.

Our ability to use future net operating loss carryforwards, research and development tax credit carryforwards, and certain other
tax attributes may be limited.

Our ability to utilize future net operating loss carryforwards ("NOLs") generated as well as research and development tax credit
carryforwards may be limited under Section 382 of the Internal Revenue Code ("IRC") or applicable state tax law. The Section 382
limitations apply if an “ownership change” occurs. Generally, an ownership change results from transactions that increase the
ownership of 5% stockholders in the stock of a corporation by more than 50% in the aggregate over a three-year period. We have

evaluated whether one or more ownership changes under Section 382 have occurred since our inception and have determined that
there have been such changes through September 30, 2022. Although we believe that these ownership changes have not resulted in
material limitations on our ability to utilize existing NOL carryforwards and research and development tax credit carryforwards, our
ability to utilize future NOLs and research and development tax credit carryforwards may be limited due to future ownership changes
or for other reasons. As a result, we may not be able to take full advantage of NOL carryforwards and research and development tax
credit carryforwards for U.S. federal and state income tax purposes.

General Risk Factors

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 have a material adverse effect on the success of 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. 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. In the event of contamination or injury resulting from our use of hazardous materials or our or third parties’ disposal 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.

We may incur substantial costs 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. Failure to comply with these laws and
regulations also may result in substantial fines, penalties or other sanctions.

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 hazardous or radioactive materials.

Our insurance policies are expensive and only protect us from specified business risks, which will leave us exposed to significant
uninsured liabilities.

We do not carry insurance for all categories of risk that our business may encounter. Some of the policies we currently maintain
include general liability, employment practices liability, property, auto, workers’ compensation, cybersecurity, products liability and
directors’ and officers’ insurance. We do not know, however, if we have adequate levels of coverage for any liability we may incur, or
whether we will always be able to continue to maintain such insurance. Any significant uninsured liability may require us to make
substantial payments, which would adversely affect our financial position and results of operations. Furthermore, any increase in the
volatility of our stock price, or changes in the insurance market generally, may result in us being required to pay substantially higher
premiums for our directors’ and officers’ liability insurance than those to which we were previously subject and may even cause one
or more of our underwriters to be unwilling to insure us.

If we fail to maintain an effective system of internal control over financial reporting, we may not be able to accurately report our
financial results or prevent fraud. As a result, stockholders could lose confidence in our financial and other public reporting,
which would harm our business and the trading price of our common stock.

Effective internal controls over financial reporting are necessary for us to provide reliable financial reports and, together with adequate
disclosure controls and procedures, are designed to prevent fraud. Any failure to implement newly required or improved controls, or
difficulties encountered in their implementation, could cause us to fail to meet our reporting obligations. In addition, any failure to
maintain effective internal control as a result of shutdowns during the global COVID-19 pandemic could result in deficiencies in
internal control. In addition, any testing by us conducted in connection with Section 404 of the Sarbanes-Oxley Act of 2002, or any
subsequent testing by our independent registered public accounting firm, may reveal deficiencies in our internal controls over financial
reporting that are deemed to be material weaknesses or that may require prospective or retroactive changes to our financial statements
or identify other areas for further attention or improvement. 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 common stock.

Our information technology systems, or those used by our CROs or other contractors or consultants, may fail or suffer other
breakdowns, cyber-attacks, or information security breaches, which could adversely affect our business.

We are increasingly dependent upon information technology systems, infrastructure, and data to operate our business. We also rely on
third party vendors and their information technology systems. Despite the implementation of security measures, our recovery systems,
security protocols, network protection mechanisms, and other security measures and those of our current or future CROs or other
contractors and consultants are vulnerable to system failure, interruption, compromise, or damage from data corruption, breakdown,

computer hacking, malicious code (such as computer viruses or worms), fraudulent activity, employee misconduct, theft, or error,
denial-of-service attacks, telecommunication, and electrical failures, natural disasters, public health epidemics, such as the COVID-19
pandemic, cyber-attacks by sophisticated nation-state and nation-state supported actors, or other system attacks, disruption, or
accidents. We receive, generate and store significant and increasing volumes of personal health data and other confidential and
proprietary information. There can be no assurance that we, or our collaborators, CROs, third-party vendors, contractors and
consultants, will be successful in efforts to detect, prevent, protect against or fully recover systems or data from all breakdowns,
service interruptions, attacks or breaches.

The costs to respond to a security breach and/or to mitigate any security vulnerabilities that may be identified could be significant, our
efforts to address these problems may not be successful, and these problems could result in unexpected interruptions, delays, cessation
of service, negative publicity, and other harm to our business and our competitive position. Remediation of any potential security
breach may involve significant time, resources, and expenses. Despite our best efforts, our network security and data recovery
measures and those of our vendors may still not be adequate to protect against such security breaches and disruptions, which could
cause harm to our business, financial condition and results of operations.

Any cybersecurity incident could adversely affect our business, by leading to, for example, the loss of confidential information or
other intellectual property, demands for ransom or other forms of blackmail or the unauthorized disclosure of personal, confidential or
proprietary information of our employees, clinical trial participants, customers and others. We could be subject to regulatory actions
taken by governmental authorities, litigation under laws that protect the privacy and security of personal information, or other forms of
legal proceedings, which could result in significant investigations, liabilities or penalties.

We may not have adequate insurance coverage for security incidents or breaches. The successful assertion of one or more large claims
against us that exceeds our available insurance coverage, or results in changes to our insurance policies (including premium increases
or the imposition of large deductible or co-insurance requirements), could have an adverse effect on our business. In addition, we
cannot be sure that our existing insurance coverage and coverage for errors and omissions will continue to be available on acceptable
terms or that our insurers will not deny coverage as to any future claim.

Use of social media could give rise to liability or reputational harm.

We and our employees use social media to communicate externally. There is risk that the use of social media by us or our employees
to communicate about our product candidates or business may give rise to liability, lead to the loss of trade secrets or other intellectual
property or result in public exposure of personal information of our employees, clinical trial patients, customers, and others.
Furthermore, negative posts or comments about us or our product candidates in social media could seriously damage our reputation,
brand image, and goodwill. Any of these events could have a material adverse effect on our business, prospects, operating results, and
financial condition and could adversely affect the price of our common stock.

ITEM 1B. UNRESOLVED STAFF COMMENTS

None.

ITEM 2.

PROPERTIES

Our corporate headquarters is located in Watertown, Massachusetts, where we lease approximately 49,000 square feet of office and
laboratory space under the 500 Arsenal Street lease agreement that expires on September 1, 2027. In May 2022, we entered into a new
lease agreement for approximately 73,000 square feet of laboratory and office space in Watertown, Massachusetts, at a to-be-
constructed facility located at Arsenal on the Charles. We expect to gain access to the facility in December 2023 to construct tenant
improvements. In conjunction with the new lease agreement at Arsenal on the Charles, we amended the 500 Arsenal Street lease
agreement to shorten the term of the lease from September 2027 to the date when the Arsenal on the Charles facility is completed and
ready for our occupancy. We also lease approximately 38,000 square feet of additional office space located in Watertown,
Massachusetts. The terms of this lease and the new lease expire on June 1, 2034.

ITEM 3.

LEGAL PROCEEDINGS

Information with respect to legal proceedings is included in Note 13 of the Notes to Consolidated Financial Statements contained in
Part II, Item 8 of this Annual Report on Form 10-K, which is incorporated herein by reference.

ITEM 4. MINE SAFETY DISCLOSURES

Not applicable.

PART II

ITEM 5. MARKET FOR THE COMPANY'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND

ISSUER PURCHASES OF EQUITY SECURITIES

Market and Stockholder Information

Our common stock has been listed on The NASDAQ Global Select Market under the symbol “ENTA” since March 21, 2013 and we
had 17 stockholders of record as of November 10, 2023. The following table shows the high and low sales price for our common stock
as reported by The NASDAQ Global Select Market for the quarterly periods in the fiscal years ended September 30, 2023 and 2022:

Fiscal 2023

High

Low

First Quarter ............................................................................................................. $
Second Quarter ........................................................................................................ $
Third Quarter ........................................................................................................... $
Fourth Quarter.......................................................................................................... $

54.20
62.06
41.45
22.15

$
$
$
$

102.00
75.28
79.50
76.36

$
$
$
$

Fiscal 2022

High

Low

39.60
38.16
19.91
11.03

57.21
54.42
37.59
47.20

We have never declared or paid cash dividends on our common stock, and we do not expect to declare or pay any cash dividends for
the foreseeable future.

Performance Graph(1)

The following graph shows a comparison from September 30, 2018 through September 30, 2023 of cumulative total return on
assumed investments of $100.00 in cash in each of our common stock, the NASDAQ Composite Index and the NASDAQ
Biotechnology Index. Such returns are based on historical results and are not intended to suggest future performance. Data for the
NASDAQ Composite Index and the NASDAQ Biotechnology Index assume reinvestment of dividends.

COMPARISON OF FIVE YEARS CUMULATIVE TOTAL RETURN
Among Enanta Pharmaceuticals, Inc., the NASDAQ Composite Index,
and the NASDAQ Biotechnology Index

(1)

This performance graph shall not be deemed to be “soliciting material” or to be “filed” with the SEC for purposes of Section 18
of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities under that Section, and shall not
be deemed incorporated by reference into any filing of Enanta Pharmaceuticals, Inc. under the Securities Act of 1933, as
amended.

ITEM 6.

[RESERVED]

ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF

OPERATIONS

You should read the following discussion and analysis of financial condition and results of operations together with our consolidated
financial statements and related notes included elsewhere in this Annual Report on Form 10-K. This discussion and other parts of this
Annual Report on Form 10-K contain forward-looking statements that involve risks and uncertainties, such as statements regarding
our plans, objectives, expectations, intentions, and projections. Our actual results could differ materially from those discussed in these
forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed
in the “Risk Factors” section of this Annual Report on Form 10-K.

Overview

•

Hepatitis B virus, or HBV, the most prevalent chronic hepatitis, which is estimated by the World Health Organization to
affect close to 300 million individuals worldwide.

Our Wholly-Owned Programs

Our primary wholly-owned research and development programs are in virology, namely RSV, SARS-CoV-2 and HBV:

•



EDP-938 - N-protein Inhibitor Candidate: We have studied EDP-938 in two Phase 2 studies that were designed to
be proof-of-concept and exploratory studies to understand the viral response better in the context of RSV infection.
These studies were conducted in otherwise healthy adults (not at high-risk for serious outcomes with RSV) infected
with RSV. The first study was a challenge study, in which healthy adults were infected with RSV in a clinical
setting. The second study, known as RSVP, was in an otherwise healthy adult outpatient population with
community-acquired RSV infection. With these studies, EDP-938 has demonstrated a favorable safety profile,
consistent with that observed in over 500 subjects exposed to EDP-938 to date. We believe that EDP-938 has the
greatest potential to show optimal efficacy in high-risk populations since these patients have reduced RSV
immunity, which manifests in a higher and longer duration of viral load and greater disease severity, allowing a
bigger window to realize the full potential of EDP-938. Based on the efficacy and growing safety profile of EDP-
938, we are continuing to evaluate EDP-938 in high-risk populations in the following ongoing clinical studies,
including pediatric patients and high-risk adults, all of which have significant unmet need:

▪

safety, tolerability, and pharmacokinetics, as well as a second part evaluating antiviral activity at the selected
dose.



•

COVID-19: We have leveraged our expertise in developing protease inhibitors to discover compounds specifically
designed to target the SARS-CoV-2 virus and potentially other coronaviruses.



▪

Phase 1 Study: In July 2022, we completed a Phase 1 study and reported positive topline results. This first-in-
human, randomized, double-blind, placebo-controlled study enrolled healthy volunteers to evaluate the safety,
tolerability, and pharmacokinetics of oral EDP-235 in single ascending doses, and multiple ascending doses,
for seven days, and the effect of food. Data from the Phase 1 study demonstrated EDP-235 was generally safe
and well-tolerated in doses up to 400 mg for seven days and adverse events were infrequent and mild.
Pharmacokinetics were supportive of once-daily dosing without ritonavir and without regard to food and
achieved target exposure levels of up to 13-fold over the plasma protein-adjusted EC90.

points, starting as early as one day after the first dose. While no difference was observed in time to
improvement in the overall group of 14 measured COVID-19 symptoms, an analysis of a subset of six
symptoms showed a two-day shorter time to improvement in patients receiving EDP-235 400 mg who were
enrolled within three days of symptom onset (p<0.01). No effect on virologic endpoints as measured in the
nose was detected due to the rapid viral decline in the placebo arm of this highly immunologically-
experienced, standard risk population. However, in the subset of patients who were nucleocapsid seronegative
(indicating no recent natural infection with SARS-CoV-2), a viral load decline was observed at day five in the
400 mg group of 0.8 log overall and 1 log in the patients with symptom onset within three days before
treatment with EDP-235.

▪

Next Steps: Going forward, we will continue to focus on potential collaborations to progress EDP-235, as we
will not advance this candidate further on our own.

•



Our Royalty Revenue Collaboration and Royalty Sale Agreement

Our royalty revenue is generated through our Collaborative Development and License Agreement with AbbVie, under which we have
discovered and out-licensed to AbbVie two protease inhibitor compounds that have been clinically tested, manufactured, and
commercialized by AbbVie as part of its combination regimens for HCV.

For accounting purposes, we continue to record 100% of HCV royalties earned under the AbbVie agreement as royalty revenue in our
consolidated statements of operation. The $200.0 million received in April 2023 was recognized on our consolidated balance sheets as
a liability, which will be reduced by the payments made to OMERS over the term of the Agreement. We recognize imputed interest
expense over the life of the royalty sale agreement based on our estimated future MAVYRET/MAVIRET royalties.

Financial Operations Overview

We are currently funding all research and development for our wholly-owned programs, which are targeted toward the discovery and
development of novel compounds. As of the date of this report, we are conducting two Phase 2 studies for EDP-938 and a Phase 2
challenge study of EDP-323. We are also conducting preclinical discovery research efforts in other disease areas.

As a result of the timing of our clinical and preclinical development programs, we expect our research and development expenses will
fluctuate from period to period. However, in the next 12 months, we expect our external research and development expenses generally

to decrease since we will not conduct any further development of EDP-235 on our own and we have made important adjustments to
reduce our spending significantly in 2024.

To date, we have funded our operations primarily through royalty payments received under our collaboration agreement with AbbVie,
a $200.0 million payment from our royalty sale agreement, and our existing cash, cash equivalents, and short-term and long-term
marketable securities. We believe that our existing cash, cash equivalents and short-term marketable securities, as well as our
continuing portion of HCV royalties, will enable us to fund our operating expenses and capital expenditure requirements through
fiscal 2027.

Revenue

Our revenue is primarily derived from our collaboration agreement with AbbVie and AbbVie’s sales of MAVYRET/MAVIRET, an 8-
week treatment regimen for chronic HCV. During the year ended September 30, 2023, we also generated $1.0 million of license
revenue from an upfront payment related to a license agreement for one of the antibacterial compounds we are no longer developing.

The following table is a summary of revenue recognized for the years ended September 30, 2023, 2022, and 2021:

Revenue

Royalty revenue................................................................... $
License revenue ...................................................................
Total revenue ........................................................................... $

78,204
1,000
79,204

86,160
—
86,160

97,074
—
97,074

2023

Years Ended September 30,
2022
(in thousands)

2021

AbbVie Agreement

To date, we have received annually tiered, double-digit royalties on our protease inhibitor product glecaprevir included in AbbVie’s
net sales of MAVYRET/MAVIRET. Under the terms of our AbbVie Agreement, 50% of AbbVie’s net sales of
MAVYRET/MAVIRET are allocated to glecaprevir. Beginning with each January 1, the cumulative net sales of
MAVYRET/MAVIRET start at zero for purposes of calculating the tiered royalties. As disclosed above regarding the OMERS royalty
sale agreement, we will only retain 45.5% of the cash payments from royalties on net sales of MAVYRET/MAVIRET occurring after
June 30, 2023 through June 30, 2032, subject to a cap on aggregate payments to OMERS equal to 1.42 times OMERS’ purchase price.

Internal Programs

As our internal product candidates are currently in Phase 1 or Phase 2 clinical development, we have not generated any revenue from
our own product sales. We do not expect to generate any revenue from product sales derived from these product candidates for at least
the next several years.

Operating Expenses

Our operating expenses are comprised of research and development expenses and general and administrative expenses.

Research and Development Expenses

Research and development expenses consist of costs incurred to conduct basic research, such as the discovery and development of
novel small molecules as therapeutics, as well as any external expenses of preclinical and clinical development activities. We expense
all costs of research and development as incurred. These expenses consist primarily of:

•

third-party contract costs relating to research, formulation, manufacturing, preclinical study, and clinical trial activities;

personnel costs, including salaries, related benefits, and stock-based compensation for employees engaged in scientific
research and development functions;

allocated facility-related costs;

laboratory consumables; and

third-party license fees.

Project-specific expenses reflect costs directly attributable to our clinical development and preclinical candidates nominated and
selected for further development. Our remaining research and development expenses are reflected in research and drug discovery,
which represent early-stage drug discovery programs. At any given time, we typically have several active early-stage research and

drug discovery projects. Our internal resources, employees and infrastructure are not directly tied to any individual research or drug
discovery project and are typically deployed across multiple projects. As such, we do not report information regarding costs incurred
for our early-stage research and drug discovery programs on a project-specific basis. We expect that our research and development
expenses will fluctuate from period to period as we advance our research and development programs. However, in the next 12 months,
we expect our external research and development expenses generally to decrease since we will not advance EDP-235 further on our
own. To date, we have not identified any significant impact of inflation on spending in research and development, but it is uncertain
whether there will be inflationary impacts in future periods.

Our research and drug discovery and development programs are in early stages; therefore, the successful development of our product
candidates is highly uncertain and may not result in approved products. Completion dates and completion costs can vary significantly
for each product candidate and are difficult to predict. Given the uncertainty associated with clinical trial enrollments and the risks
inherent in the development process, we are unable to determine the duration and completion costs of the current or future clinical
trials of our product candidates or if, or to what extent, we will generate revenue from the commercialization and sale of any of our
product candidates. We anticipate that we will make determinations as to which development programs to pursue and how much
funding to direct to each program on an ongoing basis in response to the preclinical and clinical success and prospects of each product
candidate, as well as ongoing assessments of the commercial potential of each product candidate.

General and Administrative Expenses

General and administrative expenses consist primarily of personnel costs, which include salaries, related benefits and stock-
based compensation, of our executive, finance, business and corporate development and other administrative functions. General and
administrative expenses also include travel expenses, allocated facility-related costs not otherwise included in research and
development expenses, directors’ and officers’ liability insurance premiums, professional fees for auditing, tax, and legal services, and
patent expenses.

We expect that general and administrative expenses may increase in the long term. To date we have not experienced a significant
impact of inflation on general and administrative expenses, but we anticipate inflation may impact future periods.

Other Income (Expense)

Other income (expense) consists of interest expense, interest and investment income, net and the change in fair value of our
outstanding Series 1 nonconvertible preferred stock. Interest expense consists of the non-cash interest expense and amortization of
debt issuance costs associated with the royalty sale agreement with an affiliate of OMERS. Interest income consists of interest earned
on our cash equivalents and short-term and long-term marketable securities balances. Investment income consists of the amortization
or accretion of any purchased premium or discount, respectively, on our short-term and long-term marketable securities. The change
in fair value of our Series 1 nonconvertible preferred stock relates to the remeasurement of these financial instruments from period to
period as these instruments may require a transfer of assets because of the liquidation preference features of the underlying instrument.

Income Tax (Expense) Benefit

Income tax expense for the year ended September 30, 2023 was driven by the receipt of the $200.0 million from the royalty sale
agreement, the taxable gain on which was substantially offset by net operating loss and research and development tax credit
carryforwards, a deduction for foreign derived intangible income and interest due from expected refunds from tax authorities. Income
tax benefit for the year ended September 30, 2022 is the result of the release of a state tax reserve. Income tax benefit for the year
ended September 31, 2021 is the result of the carryback of net operating losses under the Coronavirus Aid, Relief and Economic
Security Act, or CARES Act.

Critical Accounting Policies

Our consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of
America. The preparation of our consolidated financial statements and related disclosures requires us to make estimates and
assumptions that affect the reported amount of assets, liabilities, equity, revenue, costs and expenses, and related disclosures. We
believe that the estimates and assumptions involved in the accounting policies described below may have the greatest potential impact
on our consolidated financial statements and, therefore, consider these to be our critical accounting policies. We evaluate our estimates
and assumptions on an ongoing basis. Actual results may differ from these estimates under different assumptions and conditions. See
also Note 2 to the consolidated financial statements included elsewhere in this Annual Report on Form 10-K for information about
these critical accounting policies as well as a description of our other significant accounting policies.

Research and Development and Pharmaceutical Drug Manufacturing Accruals

We have entered into various contracts with third parties to perform research and development and pharmaceutical drug
manufacturing. These include contracts with contract research organizations, or CROs, clinical manufacturing organizations, or
CMOs, testing laboratories, research hospitals and not-for-profit organizations and other entities to support our research and
development activities. We expense the cost of each contract as the work is performed. When billing terms under these contracts do
not coincide with the timing of when the work is performed, we are required to make estimates of our outstanding obligations to those
third parties as of period-end. Our accrual estimates are based on a number of factors, including our knowledge of the research and
development programs and pharmaceutical drug manufacturing activities and associated timelines, invoicing to date, and the
provisions in the contract. Significant judgments and estimates are made in determining the accrued balances at the end of any
reporting period. Actual results could differ from our estimates.

Liability Related to the Sale of Future Royalties

We accounted for the $200.0 million payment from OMERS as a liability on our consolidated balance sheets because (1) under the
royalty sale agreement, OMERS will receive a portion of our royalty payments up to a capped amount of 1.42 times the original
payment to us, and (2) we have significant continuing involvement in the generation of cash flows under the AbbVie Agreement.
Interest expense for the liability related to the sale of future royalties will be recognized using the effective interest rate method over
the term of the royalty sale agreement.

The liability related to the sale of future royalties and the related interest expense are based on our current estimates of future royalties,
which we determine by using third-party forecasts of MAVYRET/MAVIRET sales. Third-party forecasts are updated periodically
based on the latest pricing, market share, and patient data. Changes in the amount or timing of estimated royalties will affect the
interest rate utilized in calculating the liability related to the sale of future royalties.

Results of Operations

2023

Years Ended September 30,
2022
(in thousands)

2021

Revenue ................................................................................... $
Research and development ......................................................
General and administrative......................................................
Interest expense .......................................................................
Interest and investment income, net ........................................
Change in fair value of Series 1 nonconvertible

preferred stock ......................................................................
Income tax (expense) benefit...................................................
Net loss .................................................................................... $

79,204
163,524
52,887
(5,148)
11,360

—
(2,821)
(133,816) $

86,160
164,522
45,482
—
1,573

83
433
(121,755) $

97,074
174,111
32,536
—
2,021

(27)
28,583
(78,996)

Comparison of the Years Ended September 30, 2023 and 2022

Revenue

We recognized revenue of $79.2 million and $86.2 million during the years ended September 30, 2023 and 2022, respectively. The
decrease in revenue year-over-year was due to AbbVie’s lower reported HCV sales in 2023, as compared to 2022. Our weighted
average royalty rate on the portion of AbbVie’s sales allocable to our protease inhibitor products was approximately 11% in both
fiscal 2023 and 2022.

Beginning with the quarter ended September 30, 2023, 54.5% of our quarterly royalty payments on net sales of
MAVYRET/MAVIRET that are included in our total revenue are paid to OMERS through June 30, 2032, subject to a cap on
aggregate payments equal to 1.42 times the purchase price. The $200.0 million received in April 2023 was recognized on our
consolidated balance sheets as a liability which will be reduced by the payments made to OMERS over the term of the royalty sale
agreement. We will continue to record 100% of HCV royalties earned under the AbbVie Agreement as royalty revenue in our
consolidated statements of operations since the AbbVie Agreement has not been amended and is independent of our agreement with
OMERS.

Our royalty revenues eligible to be earned in the future will depend on AbbVie’s HCV market share, the pricing of the
MAVYRET/MAVIRET regimen and the number of patients treated. In addition, at the beginning of each calendar year (the second
quarter of our fiscal year), our royalty rate resets to the lowest tier for each of our royalty-bearing products licensed to AbbVie.

Research and development expenses

Years Ended September 30,

2023

2022

(in thousands)

R&D programs:

Virology .................................................................................................. $
Liver disease (non-viral) .........................................................................
Other .......................................................................................................
Total research and development expenses.............................................. $

151,176
4,095
8,253
163,524

144,344
17,658
2,520
164,522

Research and development expenses decreased by $1.0 million for the year ended September 30, 2023, as compared to the same
period in 2022. The increase in costs of $6.8 million in our virology program was primarily due to an increase in clinical trial costs
and an increase in headcount, partially offset by a decrease in preclinical and manufacturing costs due to the timing of our studies in
our virology programs and decrease in depreciation expense. The costs in our non-viral liver disease program decreased by $13.6
million as we wound down our non-alcoholic steatohepatitis, or NASH, program, which is now substantially complete. The costs in
our other discovery programs increased by $5.7 million due to an increase in headcount and lab material and supply purchases.

In the next 12 months, we expect our external research and development expenses generally to decrease since we will not advance
EDP-235 further on our own.

General and administrative expenses

General and administrative expenses increased to $52.9 million for the year ended September 30, 2023, compared to $45.5 million for
the same period in 2022. The increase was primarily due to an increase in legal fees related to our patent infringement suit against
Pfizer and to a lesser extent, an increase in stock-based compensation expense.

Other income (expense)

Changes in components of other income (expense) were as follows:

Interest expense. Interest expense increased $5.1 million for the year ended September 30, 2023. The non-cash interest expense is
associated with the royalty sale agreement entered into during April 2023 with an affiliate of OMERS.

Interest and investment income, net. Interest and investment income, net increased by $9.8 million for the year ended September 30,
2023, as compared to the same period in 2022. The increase was due to an increase in our cash balance due to receipt of the $200.0
million from OMERS and changes in interest rates year over year.

Income tax (expense) benefit

We recorded income tax expense of $2.8 million and an income tax benefit of $0.4 million for the years ended September 30, 2023
and 2022, respectively. The effective tax rates used to calculate our income tax (expense) benefit for the years ended September 30,
2023 and 2022 were (2.2)% and 0.4%, respectively. Despite recording a loss before taxes, we recorded income tax expense in 2023
due to the receipt of the $200.0 million from the royalty sale agreement which was substantially offset by net operating loss
carryforwards, research and development tax credit carryforwards and a deduction for foreign derived intangible income. We recorded
an income tax benefit in 2022 due to the release of a state tax reserve during the year.

As of September 30, 2023 and 2022, we continue to record a valuation allowance against our deferred tax assets because it is more
likely than not that we will not have sufficient taxable income in the future to allow us to realize the majority of our deferred tax
assets.

Comparison of the Years Ended September 30, 2022 and 2021

For a discussion of our results of operations for the year ended September 30, 2022, as compared to the year ended September 30,
2021, see Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Results of Operations—
Comparison of the Years Ended September 30, 2022 and 2021 included in our Annual Report on Form 10-K for the fiscal year ended
September 30, 2022.

Liquidity and Capital Resources

We fund our operations with cash flows from our retained portion of our royalty revenue and our existing financial resources. At
September 30, 2023, our principal sources of liquidity were cash and cash equivalents and short-term marketable securities of $369.9
million.

The following table shows a summary of our cash flows:

2023

Years Ended September 30,
2022
(in thousands)

2021

Cash provided by (used in):

Operating activities ............................................................ $
Investing activities .............................................................
Financing activities ............................................................
Net increase (decrease) in cash, cash equivalents and

(103,154)
(53,578)
198,126

restricted cash ................................................................. $

41,394

(84,782) $
54,897
20,033

(69,996)
36,991
3,080

(9,852) $

(29,925)

Net cash used in operating activities

Cash used in operating activities was $103.2 million for the year ended September 30, 2023 as compared to cash used in operating
activities of $84.8 million for the same period in 2022. The increase in cash used in operating activities was primarily driven by timing
of operating expense cash payments, a decrease in royalty payments received under our collaboration with AbbVie and the timing of
estimated tax payments made in fiscal 2023.

For the foreseeable future, we expect to continue to incur substantial costs associated with research and development for our internally
developed programs.

Net cash provided by (used in) investing activities

Cash used in investing activities was $53.6 million for the year ended September 30, 2023 as compared to cash provided by investing
activities of $54.9 million for the same period in 2022. Our cash used in investing activities increased $108.5 million, driven by timing
of purchases, sales and maturities of marketable securities in 2023 compared to 2022 as well as increased capital expenditures in fiscal
2023 for the buildout of our leased premises at 400 Talcott Avenue.

Net cash provided by financing activities

Cash provided by financing activities was $198.1 million for the year ended September 30, 2023 as compared to cash provided by
financing activities of $20.0 million for the same period in 2022. Our cash provided by financing activities increased $178.1 million,
driven by the net proceeds from the sale of future royalties offset by a decrease in proceeds from exercise of stock options and an
increase in payments for settlement of share-based awards.

Year Ended September 30, 2022

For a discussion of our cash flows for the year ended September 30, 2022, see Item 7. Management’s Discussion and Analysis of
Financial Condition and Results of Operations—Liquidity and Capital Resources—Cash Flows included in our Annual Report on
Form 10-K for the fiscal year ended September 30, 2022.

Funding Requirements

As of September 30, 2023, we had $369.9 million in cash, cash equivalents and short-term marketable securities. We believe that our
existing cash, cash equivalents and short-term marketable securities as of September 30, 2023, as well as the cash flows from our
continuing portion of HCV royalties will be sufficient to meet our anticipated cash requirements through fiscal 2027. However, our
projection of the period of time through which our financial resources will be adequate to support our operations is a forward-looking
statement that involves risks and uncertainties, and actual results could vary materially.

Our future capital requirements are difficult to forecast and will depend on many factors, including:

•

the number and characteristics of our research and development programs;

the scope, progress, results and costs of researching and developing our product candidates on our own, including
conducting advanced clinical trials;

•

our ability to establish new collaborations, licensing or other arrangements, if any, and the financial terms of such
arrangements;

the amount of our retained portion of royalties generated from MAVYRET/MAVIRET sales under our existing
collaboration with AbbVie;

delays and additional expenses in our clinical trials;

the cost of manufacturing our product candidates for clinical development and any products we successfully
commercialize independently;

opportunities to in-license or otherwise acquire new technologies and therapeutic candidates;

costs associated with prosecuting our patent infringement suit regarding use of a coronavirus 3CL protease inhibitor in
Paxlovid, Pfizer's antiviral treatment for COVID-19;

the timing of, and the costs involved in, obtaining regulatory approvals for any product candidates we develop
independently;

the cost of commercialization activities, if any, of any product candidates we develop independently that are approved for
sale, including marketing, sales and distribution costs;

the timing and amount of any sales of our product candidates, if any, or royalties thereon;

the costs involved in preparing, filing, prosecuting, maintaining, defending and enforcing patents, including any litigation
costs and the outcomes of any such litigation; and

potential fluctuations in foreign currency exchange rates.

Off-Balance Sheet Arrangements

We do not engage in any off-balance sheet financing activities. We do not have any interest in entities referred to as variable interest
entities, which include special purpose entities and other structured finance entities.

Recently Issued Accounting Pronouncements

A description of recently issued accounting pronouncements that may potentially impact our financial position and results of
operations is set forth in Note 2 to the consolidated financial statements included in this Annual Report on Form 10-K.

Contractual Obligations and Commitments

We currently lease space in Watertown, Massachusetts, under two separate lease agreements with one landlord. We have entered into
a third lease agreement with the same landlord to lease additional laboratory and office space at a to-be-constructed facility located at
Arsenal on the Charles in Watertown, Massachusetts.

Our first lease for office and laboratory space at 500 Arsenal Street expires on September 1, 2027. In May 2022, we entered into a new
ten-year lease for laboratory and office space in Watertown, Massachusetts, adjacent to our 400 Talcott Avenue premises at Arsenal
on the Charles, at a to-be-constructed facility. We currently anticipate we will gain access to construct tenant improvements in
December 2023. In connection with this lease, we amended our 500 Arsenal Street lease to shorten the expiration date from September
1, 2027, to the date the Arsenal on the Charles facility is ready for our occupancy.

The second lease for office space located at 400 Talcott Avenue, commenced on September 24, 2018 for a term of six years. In May
2022, we amended this lease to expand the rented space and extend the lease term through June 1, 2034. We spent approximately $6.3
million in capital expenditures for the additional space, which primarily relate to tenant improvements. We received a tenant
improvement allowance from the landlord of $2.5 million.

As of September 30, 2023, we had 1.9 million outstanding shares of Series 1 nonconvertible preferred stock, all of which we classified
as a long-term liability on our consolidated balance sheet and recorded at fair value of $1.4 million. The fair value of the preferred
stock was measured based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair
value hierarchy. The fair value of these instruments represents less than 10% of liabilities as of September 30, 2023. The Series 1
nonconvertible preferred stock issued would require the payment of $2.0 million in the event of a qualifying merger or sale of the
company.

In April 2023, we entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which we were paid a $200.0 million
cash purchase price in exchange for 54.5% of our future quarterly royalty payments on net sales of MAVYRET/MAVIRET after June
30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price.

The $200.0 million received in April 2023 was recognized on our consolidated balance sheets as a liability which will be reduced by
the payments made to OMERS over the term of the Agreement.

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Interest Rate Risk

We had cash, cash equivalents and short-term marketable securities of $369.9 million and $278.5 million at September 30, 2023 and
2022, respectively, which consisted of cash, money market funds, corporate bonds, commercial paper and treasury notes. Interest
income is sensitive to changes in the general level of interest rates; however, due to the nature of these investments, a change in
market interest rates of 1% would not be expected to have a material impact on our financial condition or results of operations for
either period.

Foreign Exchange Risk

As we continue to progress our wholly-owned programs into clinical development, we will conduct clinical trials and clinical
manufacturing outside of the U.S. and thus will face exposure to movements in foreign currency exchange rates, primarily the British
Pound and Euro, against the U.S. Dollar, arising from our accounts payable and accrued expenses. During fiscal 2023 and 2022, the
impact of foreign currency exposure was immaterial and thus did not have a significant impact on our consolidated financial
statements. Our operations may become subject to more significant fluctuations in foreign currency exchange rates in the future if we
continue to contract with vendors outside of the U.S.

ITEM 8.

CONSOLIDATED FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

Our consolidated financial statements, together with the report of our independent registered public accounting firm, appear on pages
F-1 through F-25 of this Annual Report on Form 10-K.

ITEM 9.

None.

CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL
DISCLOSURE

ITEM 9A. CONTROLS AND PROCEDURES

Disclosure Controls and Procedures and Internal Control over Financial Reporting

Evaluation of Disclosure Controls and Procedures

We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in the
Company’s reports under the Securities Exchange Act of 1934, as amended, or the Exchange Act, 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 management, including our Chief Executive Officer (CEO) and Chief Financial Officer (CFO), as appropriate, to
allow timely decisions regarding required disclosure. In designing and evaluating the disclosure controls and procedures, management
recognized that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of
achieving the desired control objectives, as the Companies are designed to do, and management necessarily was required to apply its
judgment in evaluating the risk related to controls and procedures.

In connection with the preparation of this Form 10-K, as of September 30, 2023, an evaluation was performed under the supervision
and with the participation of our management, including the CEO and CFO, of the effectiveness of the design and operation of our
disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act). Based on that evaluation,
our CEO and CFO concluded that our disclosure controls and procedures were effective at a reasonable assurance level as of
September 30, 2023. These conclusions were communicated to the Audit Committee.

Changes in Internal Control over Financial Reporting

There were no changes in our internal control over financial reporting that occurred during the quarter ended September 30, 2023 that
have materially affected, or are reasonably likely to materially affect, our 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 defined in Rule
13a-15(f) and Rule 15d-15(f) under the Exchange Act. Our internal control system is designed to provide reasonable assurance to the
Company’s management and Board of Directors regarding the preparation and fair presentation of published financial statements. All

internal control systems, no matter how well designed, have inherent limitations. Therefore, even those systems determined to be
effective can provide only reasonable assurance with respect to financial statement preparation and presentation.

Our management has assessed the effectiveness of our internal control over financial reporting as of September 30, 2023. In making
this assessment, management used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission
(COSO) in its 2013 Internal Control—Integrated Framework. Based on this assessment, our management has concluded that as of
September 30, 2023, our internal control over financial reporting is effective.

The effectiveness of the Company’s internal control over financial reporting as of September 30, 2023, has been audited by
PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their attestation report, which appears in
Item 8 above.

ITEM 9B. OTHER INFORMATION

None.

ITEM 9C. DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS

Not applicable.

PART III

ITEM 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

Portions of the response to this item are incorporated herein by reference from the discussion responsive thereto in the Company’s
Definitive Proxy Statement relating to the 2024 Annual Meeting of Stockholders, also referred to as the 2024 Proxy Statement, which
will be filed within 120 days after September 30, 2023.

We have adopted a Code of Business Conduct and Ethics (the code of ethics) that applies to all of our employees, officers and
directors. The code of ethics is available on our website at http://www.enanta.com. In addition, if we make any substantive
amendments to the code of ethics or grant any waiver, including any implicit waiver, from a provision of the code to any of our
executive officers or directors, we will disclose the nature of such amendment or waiver as required by applicable law on our website
or on a Form 8-K.

ITEM 11.

EXECUTIVE COMPENSATION

The response to this item is incorporated herein by reference from the discussion responsive thereto in the 2024 Proxy Statement,
which will be filed within 120 days after September 30, 2023.

ITEM 12.

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

The response to this item is incorporated herein by reference in part from the discussion responsive thereto in the 2024 Proxy
Statement, which will be filed within 120 days after September 30, 2023.

The following table provides information about the securities authorized for issuance under the Company’s equity compensation plans
as of September 30, 2023:

Equity Compensation Plan Information

(in thousands, except per share information)

Plan Category

Equity compensation plans approved by security
holders (1)...............................................................
Equity compensation plans not approved by
security holders .....................................................
Totals ................................................................

Number of securities
to be issued
upon exercise of
outstanding options,
warrants and rights
(a)

Weighted
average
exercise price of
outstanding
options,
warrants and
rights
(b)

Number of securities
remaining available for
future issuance under
equity compensation plan
s
(excluding securities
reflected in column (a))
(c)

4,938 (2) $

—
4,938

46.57

—

1,721 (3)

—
1,721

(1)

(2)

(3)

Consists of the Company’s 2019 Equity Incentive Plan, the Company’s 2012 Equity Incentive Plan, as amended, and the
Company’s Employee Stock Purchase Plan.
Consists of shares of the Company’s common stock issuable upon exercise of outstanding options issued under the Company’s
2019 Equity Incentive Plan and the Company’s Amended and Restated 2012 Equity Incentive Plan.
Consists of shares of the Company’s common stock reserved for future issuance under the Company’s 2019 Equity Incentive
Plan and the Company’s Employee Stock Purchase Plan.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

The response to this item is incorporated herein by reference from the discussion responsive thereto in the 2024 Proxy Statement,
which will be filed within 120 days after September 30, 2023.

ITEM 14.

PRINCIPAL ACCOUNTING FEES AND SERVICES

The response to this item is incorporated herein by reference from the discussion responsive thereto in the 2024 Proxy Statement,
which will be filed within 120 days after September 30, 2023.

ITEM 15.

EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

(a) 1. FINANCIAL STATEMENTS

The financial statements are included under Part II, Item 8 of this Report.

PART IV

2. FINANCIAL STATEMENTS SCHEDULE

Schedules are omitted because they are not applicable, or are not required, or because the information is included in the consolidated
financial statements and notes thereto.

3. EXHIBITS –

The exhibits are listed below under Part IV, Item 15(b) of this Report.

(b) EXHIBITS

Exhibit
Number

Exhibit Description

Form

Date

Exhibit
Number

File Number

Filed
Herewith

Incorporated by Reference

3.1

3.2

4.1

4.2

4.3

10.1#

10.2#

10.3#

10.4†

10.5†

10.6

10.7

10.8

Restated Certificate of Incorporation of Enanta Pharmaceuticals,
Inc.

Amended and Restated Bylaws of Enanta Pharmaceuticals, Inc.
(as amended and restated in August 2015).

8-K

03/28/2013

3.1

001-35839

8-K

08/18/2015

3.2

001-35839

Specimen certificate evidencing shares of common stock.

S-1/A 02/05/2013

Specimen certificate evidencing shares of Series 1 Non-
Convertible Preferred Stock

10-K 12/11/2017

4.1

4.3

333-184779

001-35839

Description of securities registered pursuant to Section 12 of the
Securities Exchange Act of 1934

10-K 11/27/2019

4.3

001-35839

Form of Indemnification Agreement for directors and officers.

S-1/A 02/05/2013

10.7

333-184779

Amended and Restated Employment Agreement between the
Company and Jay R. Luly, Ph.D., dated as of March 4, 2013.

Form of Amended and Restated Employment Agreement for
Executive Officers other than the Chief Executive Officer.

Collaborative Development and License Agreement between the
Company and Abbott Laboratories, dated November 27, 2006;
as amended by a First Amendment to Collaborative
Development and License Agreement dated January 27, 2009
and a Second Amendment to Collaborative Development and
License Agreement dated December 9, 2009 (assigned to
AbbVie Inc. as of January 1, 2013).

Third Amendment to Collaborative Development and License
Agreement between the Company and AbbVie dated October
20, 2014.

Fourth Amendment to Collaborative Development and License
Agreement between the Company and AbbVie dated as of
March 3, 2015.

Lease Agreement between Company and ARE-500 Arsenal
Street LLC, dated as of April 15, 2011.

S-1/A 03/05/2013

10.5

333-184779

S-1/A 03/05/2013

10.17

333-184779

8-K

02/05/2021

10.1

001-35839

8-K

02/05/2021

10.2

001-35839

10-Q 05/08/2015

10.1

001-35839

S-1

11/06/2012

10.6

333-184779

First Amendment to Lease Agreement made as of March 5,
2015 between the Company and ARE-500 Arsenal Street LLC.

10-Q 05/08/2015

10.2

001-35839

10.9

10.10

10.11

10.12

Royalty Purchase Agreement between Enanta Pharmaceuticals,
Inc. and OCM Life Sciences Portfolio LP dated as of April 25,
2023

Second Amendment to Lease made as of May 12, 2022 by and
between ARE-500 Arsenal Street, LLC and the Company.

Lease Agreement between Company and Athena Arsenal, LLC,
dated as of September 27, 2018.

First Amendment to Lease Agreement made as of May 12, 2022
by and between ARE-MA Region No. 75, LLC and the
Company.

8-K

04/27/2023

10.1

001-35839

8-K

05/17/2022

10.1

001-35839

10-K 11/29/2018

10.10

001-35839

8-K

05/17/2022

10.2

001-35839

10.13

Lease Agreement made as of May 12, 2022 by and between
ARE-MA Region No. 75, LLC and the Company.

8-K

05/17/2022

10.3

001-35839

10.14#

10.15#

10.16#

10.17#

10.18#

10.19#

2012 Equity Incentive Plan (As adjusted to reflect the
application of the 1-for-4.31 reverse stock split of the
Company’s common stock effected on March 1, 2013).

10-K/A 01/06/2017

10.14

001-35839

Form of Incentive Stock Option Agreement under 2012 Equity
Incentive Plan.

S-1/A 03/05/2013

10.13

333-184779

Form of Non-Statutory Stock Option Agreement under 2012
Equity Incentive Plan.

Form of Non-Statutory Stock Option Certificate for directors
under 2012 Equity Incentive Plan.

S-1/A 03/05/2013

10.14

333-184779

S-1/A 03/05/2013

10.15

333-184779

Form of Performance Share Unit Certificate under 2012 Equity
Incentive Plan.

10-K 12/11/2017

10.18

001-35839

Form of Relative Total Stockholder Return Unit Certificate
under 2012 Equity Incentive Plan.

10-K 12/11/2017

10.19

001-35839

10.20#

Employee Stock Purchase Plan.

S-1/A 02/05/2013

10.16

333-184779

10.21#

2019 Equity Incentive Plan (As amended March 2023)

8-K

03/07/2023

10.1

001-35839

10.22#

10.23#

10.24#

10.25#

10.26#

21.1

23.1

31.1

31.2

Form of Notice of Grant of Non-Statutory Stock Option under
2019 Equity Incentive Plan.

10-Q 05/10/2019

10.2

001-35839

Form of Notice of Grant of Non-Statutory Stock Option for
Directors under 2019 Equity Incentive Plan.

Form of Relative Total Stockholder Return Unit Certificate
under 2019 Equity Incentive Plan.

10-Q 05/10/2019

10.3

001-35839

10-Q 05/10/2019

10.4

001-35839

Form of Performance Share Unit Certificate under 2019 Equity
Incentive Plan.

10-Q 05/10/2019

10.5

001-35839

Form of Notice of Restricted Stock Unit Award under 2019
Equity Incentive Plan.

10-K 11/25/2020

10.27

001-35839

Subsidiaries of the Company.

Consent of PricewaterhouseCoopers LLP, Independent
Registered Public Accounting Firm.

Certification of the Chief Executive Officer pursuant to Rule
13a-14(a) or 15d-14(a) of the Securities Exchange Act of 1934.

Certification of Chief Financial Officer pursuant to Rule 13a-
14(a) or 15d-14(a) of the Securities Exchange Act of 1934.

32.1

101.INS

Certification of the Chief Executive Officer and Chief Financial
Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant
to Section 906 of the Sarbanes-Oxley Act of 2002.

Inline XBRL Instance Document – the instance document does
not appear in the Interactive Data File because XBRL tags are
embedded within the Inline XBRL document.

101.SCH Inline XBRL Taxonomy Extension Schema Document

101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase

Document

101.DEF

Inline XBRL Taxonomy Extension Definition Linkbase
Document

101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document

101.PRE

Inline XBRL Taxonomy Extension Presentation Linkbase
Document

104

#
†

††

Cover Page Interactive Data File (embedded within the Inline
XBRL document)

Management contract or compensatory plan, contract or agreement.
Confidential treatment granted as to portions of this Exhibit. The confidential portions of this Exhibit have been omitted and are
marked by asterisks.
This Exhibit has been filed separately with the commission pursuant to an application for confidentiality treatment. The
confidential portions of this Exhibit have been omitted and are marked by asterisks.

ITEM 16.

FORM 10-K SUMMARY

None.

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Company has duly caused this report
to be signed on its behalf by the undersigned, thereunto duly authorized, this 22nd day of November, 2023.

SIGNATURES

ENANTA PHARMACEUTICALS, INC.

By:

/s/ Jay R. Luly, Ph.D.
Jay R. Luly, Ph.D.
Chief Executive Officer

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on
behalf of the Company in the capacities and on the dates indicated.

Signature

/s/ Jay R. Luly, Ph.D.
Jay R. Luly, Ph.D.

/s/ Paul J. Mellett
Paul J. Mellett

/s/ Bruce L.A. Carter, Ph.D.

Bruce L.A. Carter, Ph.D.

/s/ Mark G. Foletta

Mark G. Foletta

/s/ Yujiro S. Hata

Yujiro S. Hata

/s/ Kristine Peterson

Kristine Peterson

/s/ Lesley Russell, MB. Ch.B., MRCP

Lesley Russell, MB. Ch.B., MRCP

/s/ Terry Vance

Terry Vance

Title

Date

President and Chief Executive
Officer and Director
(Principal Executive Officer)

Chief Financial Officer
(Principal Financial and
Accounting Officer)

November 22, 2023

Director

November 22, 2023

Director

November 22, 2023

ITEM 8.

CONSOLIDATED FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

ENANTA PHARMACEUTICALS, INC.

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Report of Independent Registered Public Accounting Firm (PCAOB ID 238)
Consolidated Balance Sheets
Consolidated Statements of Operations
Consolidated Statements of Comprehensive Loss
Consolidated Statements of Stockholders’ Equity
Consolidated Statements of Cash Flows
Notes to Consolidated Financial Statements

Page
F-2
F-4
F-5
F-6
F-7
F-8
F-9

F-1

Report of Independent Registered Public Accounting Firm

To the Board of Directors and Stockholders of Enanta Pharmaceuticals, Inc.

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of Enanta Pharmaceuticals, Inc. and its subsidiary (the “Company”)
as of September 30, 2023 and 2022, and the related consolidated statements of operations, of comprehensive loss, of stockholders’
equity and of cash flows for each of the three years in the period ended September 30, 2023, including the related notes (collectively
referred to as the “consolidated financial statements”). We also have audited the Company's internal control over financial reporting as
of September 30, 2023, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of
Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of
the Company as of September 30, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the
period ended September 30, 2023 in conformity with accounting principles generally accepted in the United States of America. Also
in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of September
30, 2023, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO.

Basis for Opinions

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over
financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s
Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the
Company’s consolidated financial statements and on the Company's internal control over financial reporting 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 audits
to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to
error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the
consolidated 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 consolidated 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 consolidated financial statements. Our audit of internal control over financial reporting
included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and
testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included
performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable
basis for our opinions.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed 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. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the
maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the
company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in
accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in
accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding
prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect
on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections
of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in
conditions, or that the degree of compliance with the policies or procedures may deteriorate.

F-2

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements
that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are
material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The
communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a
whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or
on the accounts or disclosures to which it relates.

Research and Development and Pharmaceutical Drug Manufacturing Accruals

As described in Notes 2 and 6 to the consolidated financial statements, the Company has entered into various contracts with third
parties to perform research and development and pharmaceutical drug manufacturing. When billing terms under these contracts do not
coincide with the timing of when the work is performed, management is required to make estimates of outstanding obligations to those
third parties as of period end. Within accrued expenses and other current liabilities, total accrued research and development expenses
and accrued pharmaceutical drug manufacturing amounted to $6.1 million and $3.1 million as of September 30, 2023, respectively.
The accrual estimates are based on a number of factors, including management’s knowledge of the research and development
programs and pharmaceutical drug manufacturing activities and associated timelines, invoicing to date, and the provisions in the
contract. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period.

The principal considerations for our determination that performing procedures relating to research and development and
pharmaceutical drug manufacturing accruals is a critical audit matter are the significant judgment by management in developing the
accrual estimates, as the estimates are based on a number of factors, including management’s knowledge of the research and
development programs and pharmaceutical drug manufacturing activities and associated timelines, invoicing to date, and the
provisions in the contracts, which in turn led to a high degree of auditor judgment, subjectivity and effort in performing procedures
and evaluating management’s significant assumptions related to progress towards completion of the research and development
programs and pharmaceutical drug manufacturing activities.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion
on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to accrued research
and development expenses and accrued pharmaceutical drug manufacturing, including controls over the review of contracts and
assessment of progress of the accrued research and development programs and accrued pharmaceutical drug manufacturing activities.
These procedures also included, among others (i) testing management’s process for developing estimates based upon the progress of
the research and development programs and pharmaceutical drug manufacturing activities; (ii) evaluating the appropriateness of the
method used by management to develop the estimates; (iii) reading research and development and pharmaceutical drug manufacturing
contracts on a test basis; (iv) evaluating the completeness and accuracy of data used by management; and (v) evaluating the
reasonableness of significant assumptions related to the progress towards completion. Evaluating management’s assumptions related
to progress towards completion of the research and development programs and pharmaceutical drug manufacturing activities included
evaluating whether the assumptions were reasonable considering the associated timelines, invoicing to date and the provisions in the
contracts.

/s/ PricewaterhouseCoopers LLP
Boston, Massachusetts
November 22, 2023

We have served as the Company’s auditor since 1999.

F-3

ENANTA PHARMACEUTICALS, INC.

CONSOLIDATED BALANCE SHEETS
(in thousands, except per share data)

Assets
Current assets:

Cash and cash equivalents................................................................................. $
Short-term marketable securities ......................................................................
Accounts receivable ..........................................................................................
Prepaid expenses and other current assets ........................................................
Income tax receivable .......................................................................................
Total current assets........................................................................................
Long-term marketable securities...........................................................................
Property and equipment, net .................................................................................
Operating lease, right-of-use assets ......................................................................
Restricted cash ......................................................................................................
Other long-term assets ..........................................................................................

Total assets .................................................................................................... $

Liabilities and Stockholders' Equity
Current liabilities:

Accounts payable .............................................................................................. $
Accrued expenses and other current liabilities..................................................
Liability related to the sale of future royalties ..................................................
Operating lease liabilities..................................................................................
Total current liabilities ..................................................................................
Liability related to the sale of future royalties, net of current portion ..................
Operating lease liabilities, net of current portion..................................................
Series 1 nonconvertible preferred stock................................................................
Other long-term liabilities .....................................................................................
Total liabilities ..............................................................................................

Commitments and contingencies (Note 13)
Stockholders' equity:

Common stock; $0.01 par value per share, 100,000 shares authorized;

21,059 and 20,791 shares issued and outstanding at September 30, 2023
and September 30, 2022, respectively ...........................................................
Additional paid-in capital..................................................................................
Accumulated other comprehensive loss............................................................
Accumulated deficit ..........................................................................................
Total stockholders' equity .............................................................................
Total liabilities and stockholders' equity....................................................... $

September 30,
2023

September 30,
2022

85,388
284,522
8,614
13,263
31,004
422,791
—
11,919
22,794
3,968
803
462,275

4,097
18,339
35,076
5,275
62,787
159,429
21,238
1,423
663
245,540

43,994
205,238
20,318
13,445
28,718
311,713
29,285
6,173
23,575
3,968
696
375,410

6,000
20,936
—
2,891
29,827
—
22,372
1,423
454
54,076

211
424,693
(1,174)
(206,995)
216,735
462,275

208
398,029
(3,724)
(73,179)
321,334
375,410

The accompanying notes are an integral part of these consolidated financial statements.

F-4

ENANTA PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS
(in thousands, except per share data)

2023

Years Ended September 30,
2022

2021

Revenue

Royalty revenue................................................................................. $
License revenue .................................................................................
Total revenue.................................................................................

78,204
1,000
79,204

86,160
—
86,160

97,074
—
97,074

Operating expenses:

Research and development ................................................................
General and administrative................................................................
Total operating expenses ...............................................................
Loss from operations .............................................................................
Other income (expense):

Interest expense .................................................................................
Interest and investment income, net ..................................................
Change in fair value of Series 1 nonconvertible preferred stock ......
Total other income, net..................................................................
Loss before income taxes ......................................................................
Income tax (expense) benefit ............................................................
Net loss .................................................................................................. $
Net loss per share, basic and diluted ..................................................... $
Weighted average common shares outstanding, basic and diluted .......

163,524
52,887
216,411
(137,207)

(5,148)
11,360
—
6,212
(130,995)
(2,821)
(133,816) $
(6.38) $

164,522
45,482
210,004
(123,844)

—
1,573
83
1,656
(122,188)
433
(121,755) $
(5.91) $

20,969

20,603

174,111
32,536
206,647
(109,573)

—
2,021
(27)
1,994
(107,579)
28,583
(78,996)
(3.92)
20,171

The accompanying notes are an integral part of these consolidated financial statements.

F-5

ENANTA PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
(in thousands)

Net loss....................................................................................................... $
Other comprehensive income (loss):
Net unrealized gains (losses) on marketable securities............................
Total other comprehensive income (loss) ..........................................
Comprehensive loss ................................................................................... $

Years Ended September 30,
2022
(121,755) $

2023
(133,816) $

2021
(78,996)

2,550
2,550
(131,266) $

(3,342)
(3,342)
(125,097) $

(1,226)
(1,226)
(80,222)

The accompanying notes are an integral part of these consolidated financial statements.

F-6

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7
-
F

ENANTA PHARMACEUTICALS, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS
(in thousands)

Cash flows from operating activities
Net loss .................................................................................................. $
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense...................................................
Depreciation and amortization expense .............................................
Non-cash interest expense associated with the sale of future royalties
Non-cash royalty revenue .................................................................
Deferred income taxes ......................................................................
Premium paid on marketable securities .............................................
Amortization (accretion) of premiums (discounts) on marketable

securities........................................................................................
Loss on disposal of property and equipment ......................................
Change in fair value of Series 1 nonconvertible preferred stock .........
Other non-cash items ........................................................................
Change in operating assets and liabilities:

Accounts receivable........................................................................
Prepaid expenses and other current assets........................................
Income tax receivable .....................................................................
Operating lease, right-of-use assets .................................................
Other long-term assets ....................................................................
Accounts payable............................................................................
Accrued expenses ...........................................................................
Operating lease liabilities................................................................
Other long-term liabilities ...............................................................
Net cash used in operating activities..................................................

Cash flows from investing activities
Purchase of marketable securities............................................................
Proceeds from maturities and sale of marketable securities ......................
Purchase of property and equipment........................................................
Net cash provided by (used in) investing activities ............................

Cash flows from financing activities
Proceeds from exercise of stock options ..................................................
Proceeds from the sale of future royalties ................................................
Payments for debt issuance costs.............................................................
Payments for settlement of share-based awards .......................................
Net cash provided by financing activities ..........................................
Net increase (decrease) in cash, cash equivalents and restricted cash .
Cash, cash equivalents and restricted cash at beginning of period ............
Cash, cash equivalents and restricted cash at end of period ...................... $
Supplemental cash flow information:

2023

Years Ended September 30,
2022

2021

(133,816) $

(121,755) $

(78,996)

28,216
2,371
5,148
(10,318)
—
(73)

(2,856)
150
—
—

11,704
182
(2,286)
4,598
(107)
(1,151)
(2,558)
(2,567)
209
(103,154)

(373,391)
328,871
(9,058)
(53,578)

2,208
200,000
(325)
(3,757)
198,126
41,394
47,962
89,356

26,969
2,973
—
—
—
(846)

1,171
—
(83)
—

3,258
743
8,537
4,776
(604)
(4,634)
(1,477)
(3,706)
(104)
(84,782)

(171,446)
228,468
(2,125)
54,897

21,262
—
—
(1,229)
20,033
(9,852)
57,814
47,962

20,991
3,334
—
—
345
(4,028)

2,116
—
27
(97)

(84)
(533)
(24,214)
5,418
—
3,774
8,350
(5,879)
(520)
(69,996)

(307,348)
345,089
(750)
36,991

3,614
—
—
(534)
3,080
(29,925)
87,739
57,814

— $

1,215
23,910

$
$

137
3,320

$
$

Cash paid for taxes ............................................................................. $

4,899

Supplemental disclosure of noncash information:

Purchases of fixed assets included in accounts payable and accrued

expenses .......................................................................................... $
Operating lease liabilities arising from obtaining right-of-use assets .... $

424
3,817

The accompanying notes are an integral part of these consolidated financial statements.

F-8

ENANTA PHARMACEUTICALS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
(Amounts in thousands, except per share data)

1. Nature of the Business

Enanta Pharmaceuticals, Inc. (collectively with its subsidiary, the “Company”), incorporated in Delaware in 1995, is a biotechnology
company that uses its robust, chemistry-driven approach and drug discovery capabilities to become a leader in the discovery and
development of small molecule drugs with an emphasis on treatments for viral infections. The Company discovered glecaprevir, the
second of two protease inhibitors discovered and developed through its collaboration with AbbVie for the treatment of chronic
infection with hepatitis C virus (“HCV”). Glecaprevir is co-formulated as part of AbbVie’s leading direct-acting antiviral (“DAA”)
combination treatment for HCV, which is marketed under the tradenames MAVYRET® (U.S.) and MAVIRET® (ex-U.S.)
(glecaprevir/pibrentasvir). Royalties from the Company’s AbbVie collaboration and its existing financial resources provide funding to
support the Company’s wholly-owned research and development programs, which are primarily focused on the following disease
targets: respiratory syncytial virus (“RSV”), SARS-CoV-2 and hepatitis B virus (“HBV”).

The Company is subject to many of the risks common to companies in the biotechnology industry, including but not limited to, the
uncertainties of research and development, competition from technological innovations of others, dependence on collaborative
arrangements, protection of proprietary technology, dependence on key personnel and compliance with government regulation.
Product candidates currently under development will require significant additional research and development efforts, including
extensive preclinical and clinical testing and regulatory approvals, prior to commercialization. These efforts require significant
amounts of capital, adequate personnel and infrastructure, and extensive compliance reporting capabilities.

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements include those of the Company and its subsidiary, Enanta Pharmaceuticals
Security Corporation, after elimination of all intercompany accounts and transactions. The accompanying consolidated financial
statements have been prepared in conformity with accounting principles generally accepted in the United States of America
(“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the
Accounting Standards Codification and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board
(“FASB”).

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the
consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant
estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, management’s
judgments with respect to its revenue arrangements; liability related to the sale of future royalties; valuation of stock-based awards and
the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and
experience.

Cash Equivalents and Marketable Securities

The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at acquisition date to
be cash equivalents. Marketable securities with original maturities of greater than ninety days and remaining maturities of less than
one year from the balance sheet date are classified as short-term marketable securities. Marketable securities with remaining maturities
of greater than one year from the balance sheet date are classified as long-term marketable securities.

The Company classifies all of its marketable securities as available-for-sale. The Company continually evaluates the credit ratings of
its investment portfolio and underlying securities. The Company invests in accordance with its investment policy and invests at the
date of purchase in securities with a rating of A3/A- or higher according to Moody’s or S&P or A- by Fitch. The Company reports
available-for-sale investments at fair value as of each balance sheet date and records any unrealized gains or losses as a component of
stockholders’ equity. The cost of securities sold is determined on a specific identification basis and realized gains and losses are
included in other income (expense) within the consolidated statements of operations. When the fair value is below the amortized cost
of a marketable security, an estimate of expected credit losses is made. The credit-related impairment amount is recognized in the
consolidated statements of operations. Credit losses are recognized through the use of an allowance for credit losses account in the
consolidated balance sheet and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the
allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to
sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the
amortized cost basis of the asset over its fair value is recorded in the consolidated statements of operations. There were no credit
losses recorded during the years ended September 30, 2023, 2022, and 2021.

F-9

Restricted Cash

As of September 30, 2023 and 2022, the Company had outstanding letters of credit collateralized by a money market account of
$3,968, to the benefit of the landlord of the Company’s building leases. This amount was classified as long-term restricted cash as of
September 30, 2023 and 2022.

Concentration of Credit Risk and of Significant Customers and Suppliers

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents,
short-term and long-term marketable securities and accounts receivable. The Company has all cash and investment balances at one
accredited financial institution, including cash in amounts that exceed federally insured limits. The Company does not believe it is
subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

The Company has historically generated the majority of its revenue from its collaborative research and license agreements. As of
September 30, 2023 and 2022, accounts receivable consisted of amounts due from the Company’s principal collaborator (see Note 7).

The Company is completely dependent on third-party manufacturers for product supply for preclinical and clinical research activities.
The Company relies and expects to continue to rely exclusively on several manufacturers to supply the Company with its drug supply
requirements related to these activities. These research programs would be adversely affected by a significant interruption in the
supply from these third-party manufacturers.

Fair Value Measurements

Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received
for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an
orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must
maximize the use of observable inputs and minimize the use of unobservable inputs. A fair value hierarchy is based on three levels of
inputs that are used to measure fair value, of which the first two levels are considered observable and the last is considered
unobservable:

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

Level 2—Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or
liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are
observable or can be corroborated by observable market data.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the
fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The Company’s instruments that are carried at fair value are cash equivalents, short-term and long-term marketable securities and the
Series 1 nonconvertible preferred stock. The carrying values of accounts receivable, prepaid and other assets, accounts payable and
accrued expenses approximate their fair value due to the short-term nature of these assets and liabilities.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line
method over the following estimated useful lives:

Laboratory and office equipment
Leasehold improvements
Purchased software
Computer equipment
Furniture

5 years
Shorter of life of lease or estimated useful life
3 years
3 years
7 years

Expenditures for repairs and maintenance of assets are charged to expense as incurred. Costs of major additions and betterments are
capitalized and depreciated on a straight-line basis over their useful lives. Upon retirement or sale, the cost and related accumulated
depreciation of assets disposed are removed from the accounts and any resulting gain or loss is included in income from operations in
the consolidated statements of operations.

Leases

The Company accounts for a contract as a lease when it has the right to control the asset for a period of time while obtaining
substantially all of the asset’s economic benefits. The Company determines if an arrangement is a lease or contains an embedded lease
at inception. For arrangements that meet the definition of a lease, the Company determines the initial classification and measurement
of its right-of-use asset and lease liability at the lease commencement date and thereafter if modified. The lease term includes any

F-10

renewal options that the Company is reasonably assured to exercise. The present value of lease payments is determined by using the
interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its estimated secured incremental
borrowing rate for that lease term. The Company’s policy is to not record leases with an original term of 12 months or less on its
consolidated balance sheets and recognizes those lease payments in the consolidated statements of operations on a straight-line basis
over the lease term.

In addition to rent, the leases may require the Company to pay additional costs, such as utilities, maintenance and other operating
costs, which are generally referred to as non-lease components. The Company has elected to not separate lease and non-lease
components. Only the fixed costs for lease components and their associated non-lease components are accounted for as a single lease
component and recognized as part of a right-of-use asset and lease liability. Rent expense for operating leases is recognized on a
straight-line basis over the reasonably assured lease term based on the total lease payments and is included in operating expense in the
consolidated statements of operations.

Impairment of Long-Lived Assets

The Company reviews long-lived assets, primarily property and equipment and right-of-use assets, for impairment whenever events or
changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the
Company considers in deciding when to perform an impairment review include significant underperformance of the business in
relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the
assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of
undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An
impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are
less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its
fair value, determined based on discounted cash flows. To date, the Company has not recorded any impairment losses on long-lived
assets.

Liability Related to the Sale of Future Royalties

In April 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was
paid a $200,000 cash purchase price in exchange for 54.5% of the Company’s future quarterly royalty payments on net sales of
MAVYRET/MAVIRET. The Company recognized the $200,000 received from OMERS as a liability on its consolidated balance
sheets because the $200,000 will be paid back to OMERS up to a 1.42 capped amount and the Company has significant continuing
involvement under the AbbVie Agreement. Interest expense for the liability related to the sale of future royalties is recognized using
the effective interest rate method over the term of the royalty sale agreement.

The liability related to the sale of future royalties and related interest expense are based on current estimates of future royalties, which
the Company determines by using third-party forecasts of MAVYRET/MAVIRET sales. The Company periodically assesses the
forecasted sales and to the extent the amount or timing of future estimated royalty payments is materially different than previous
estimates, the Company will account for any such change by adjusting the liability related to the sale of future royalties and
prospectively recognizing the related non-cash interest expense.

Revenue Recognition

The Company’s revenue has been generated primarily through collaborative research and license agreements. The terms of these
agreements contain multiple deliverables, which may include (i) licenses, (ii) research and development activities, and (iii)
participation in joint research and development steering committees. The terms of these agreements may include nonrefundable
upfront license fees, payments for research and development activities, payments based upon the achievement of certain milestones,
and royalty payments based on product sales derived from the collaboration.

The Company recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the
consideration to which the Company expects to be entitled in exchange for those goods or services. The Company receives sales-based
royalties for which the license is deemed to be the predominant item to which the royalties relate and thus the Company recognizes
sales-based royalties as the underlying sales are earned.

Research and Development Costs

Included in research and development costs are wages, stock-based compensation and benefits of employees performing research and
development, third-party license fees and other operational costs related to the Company’s research and development activities,
including facility-related expenses and external costs of outside contractors engaged to conduct both preclinical and clinical studies
and manufacture quantities of product for preclinical and clinical studies. The Company expenses the cost of each contract as the work
is performed.

F-11

Upfront payments and milestone payments made for the licensing of technology are expensed as research and development in the
period in which they are incurred. Advance payments for goods or services to be received in the future for use in research and
development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the
services are performed.

Research and Development and Pharmaceutical Drug Manufacturing Accruals

The Company has entered into various contracts with third parties to perform research and development and pharmaceutical drug
manufacturing. This includes contracts with contract research organizations (“CROs”), clinical manufacturing organizations
(“CMOs”), testing laboratories, research hospitals and not for profit organizations and other entities to support our research and
development activities. When billing terms under these contracts do not coincide with the timing of when the work is performed, the
Company is required to make estimates of outstanding obligations to those third parties as of period end. The accrual estimates are
based on a number of factors, including the Company’s knowledge of the research and development programs and pharmaceutical
drug manufacturing activities and associated timelines, invoicing to date, and the provisions in the contract. Significant judgments and
estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from our
estimates.

Patent Costs

All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and
administrative expenses as incurred.

Stock-Based Compensation

The Company measures all stock options and other stock-based awards granted to employees at fair value on the date of grant. The
Company uses the Black-Scholes option-pricing model in the valuation of its stock options. The fair value of restricted stock units
with service-based and performance-based vesting is based on the fair value of the stock on the date of grant. The Company uses the
Monte-Carlo model to calculate the fair value on the date of grant of market-based awards. The fair value of service-based awards is
recognized as stock-based compensation expense over the requisite service period, which is generally the vesting period of the
respective award. For awards with graded vesting, the straight-line method of expense recognition is applied to all awards with
service-only based conditions. The Company uses the graded-vesting method to record the expense of awards with both service-based
and performance-based vesting conditions, commencing once achievement of the performance condition becomes probable. The
Company classifies stock-based compensation expense in the consolidated statements of operations in the same manner in which the
award recipient’s payroll costs are classified. The Company accounts for stock-based compensation expense related to forfeitures as
the forfeitures occur.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and
liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s
tax returns. Deferred taxes are determined based on the difference between the financial reporting and tax basis of assets and liabilities
using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and
liabilities are recorded in income tax expense.

The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it
believes based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not
be realized, a valuation allowance is established through a charge to income tax expense. The realization of deferred tax assets is
dependent upon the Company’s ability to generate future taxable income during the periods in which those temporary differences
become deductible. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and
considering prudent and feasible tax planning strategies.

Uncertain tax positions represent tax positions for which reserves have been established. The Company accounts for uncertainty in
income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount to be
recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by
the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine
the amount of benefit to be recognized in the financial statements. The amount that may be recognized is the largest amount that has a
greater than 50% likelihood of being realized upon ultimate settlement. Income tax expense includes the effects of any resulting tax
reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Net Income (Loss) per Share

Basic net income (loss) per common share is computed by dividing the net income (loss) by the weighted average number of shares of
common stock outstanding for the period. Diluted net income (loss) per common share is computed by dividing net income (loss) by

F-12

the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the
dilutive effect of outstanding stock options and unvested restricted stock units. For periods in which the Company reported a net loss,
diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to
have been issued if their effect is anti-dilutive.

The Company reported net losses for each of the years ended September 30, 2023, 2022, and 2021. The Company excluded the
following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net
loss per share for the periods indicated because including them would have had an anti-dilutive effect:

Options to purchase common stock .......................................
Unvested rTSRUs ..................................................................
Unvested PSUs ......................................................................
Unvested restricted stock units ..............................................

Segment Data

Years Ended September 30,

2023

2022

2021

4,365
81
81
411

(in thousands)

3,993
101
101
219

3,852
111
111
117

The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions.
The Company is a biotechnology company focused on discovering and developing small molecule drugs, with an emphasis on
treatments for viral infections. Revenue is generated exclusively from transactions occurring with partners located in the United
States, and all assets are held in the United States.

Comprehensive Income (Loss)

Comprehensive income (loss) includes net income (loss) as well as other changes in stockholders’ equity that result from transactions
and economic events other than those with stockholders. The Company’s only element of other comprehensive income (loss) is
unrealized gains and losses on available-for-sale marketable securities.

Going Concern

In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40) (“ASU
2014-15”). The Company adopted this standard as of September 30, 2017. The standard requires the Company to assess its ability to
continue as a going concern one year beyond the date of filing and, in certain circumstances, provide additional footnote disclosures.
Based on a detailed cash forecast incorporating current research and development activities and related spending plans, the Company
believes that its current cash, cash equivalents and short-term marketable securities on hand at September 30, 2023 is sufficient to fund
operations for at least the next twelve months beyond the date of issuance of these consolidated financial statements. The amount of
capital available will depend on the Company’s management of its existing cash, cash equivalents and short-term marketable
securities, as well as the level of future royalties the Company earns under its agreement with AbbVie. If the Company should require
financing beyond these resources to fund its research and development efforts, it may not be able to obtain financing on acceptable
terms, or at all.

Recently Issued Accounting Pronouncements

Accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption
until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

F-13

3. Fair Value of Financial Assets and Liabilities

The following tables present information about the Company’s financial assets and liabilities that were subject to fair value
measurement on a recurring basis as of September 30, 2023 and 2022 and indicate the fair value hierarchy of the valuation inputs
utilized to determine such fair value:

Fair Value Measurements at September 30, 2023 Using:

Level 1

Level 2

Level 3

Total

(in thousands)

Assets:
Cash equivalents:
Money market funds................................... $
U.S. Treasury notes ....................................
Marketable securities:
U.S. Treasury notes ....................................
Corporate bonds..........................................
Commercial paper ......................................

55,357 $
29,755

— $
—

236,782
—
—
321,894

—
26,435
21,305
47,740

— $
—

—
—
—
—

Liabilities:
Series 1 nonconvertible preferred stock .....

—
— $

1,423
1,423 $

55,357
29,755

236,782
26,435
21,305
369,634

1,423
1,423

Assets:
Cash equivalents:
Money market funds................................... $
Marketable securities:
U.S. Treasury notes ....................................
Corporate bonds..........................................
Commercial paper ......................................

Fair Value Measurements at September 30, 2022 Using:

Level 1

Level 2

Level 3

Total

(in thousands)

13,905 $

— $

13,905

91,328
—
—
105,233

—
76,411
66,784
143,195

—
—
—
—

91,328
76,411
66,784
248,428

1,423
1,423

Liabilities:
Series 1 nonconvertible preferred stock .....

—
— $

1,423
1,423 $

Cash equivalents at September 30, 2023 and 2022 consist of money market funds and U.S. Treasury notes that are readily convertible
to cash and with less than 90 days until maturity.

During the years ended September 30, 2023, 2022, and 2021, there were no transfers between Level 1, Level 2 and Level 3.

The fair value of Level 2 instruments classified as marketable securities were determined through third-party pricing services. The
pricing services use many observable market inputs to determine value, including reportable trades, benchmark yields, credit spreads,
broker/dealer quotes, bids, offers, and current spot rates.

The outstanding shares of Series 1 nonconvertible preferred stock as of September 30, 2023 and 2022 are measured at fair value.
These outstanding shares are financial instruments that might require a transfer of assets because of the liquidation features in the
contract and are therefore recorded as liabilities and measured at fair value. The fair value of the outstanding shares is based on
significant inputs not observable in the market, which represent a Level 3 measurement within the fair value hierarchy. The Company
utilizes a probability-weighted valuation model, which takes into consideration various outcomes that may require the Company to
transfer assets upon liquidation. Changes in the fair values of the Series 1 nonconvertible preferred stock are recognized in other
income (expense) in the consolidated statements of operations.

F-14

The recurring Level 3 fair value measurements of the Company’s outstanding Series 1 nonconvertible preferred stock using
probability-weighted discounted cash flow include the following significant unobservable inputs:

Series 1 nonconvertible preferred stock

Unobservable Input

Probabilities of payout
Discount rate

Range
September 30,

2023
0%-65%
7.25%

2022
0%-65%
7.25%

The following table provides a rollforward of the aggregate fair value of the Company’s outstanding Series 1 nonconvertible preferred
stock for which fair value is determined by Level 3 inputs:

Balance, September 30, 2020.................................................................................
Change in fair value .............................................................................................
Balance, September 30, 2021.................................................................................
Change in fair value .............................................................................................
Balance, September 30, 2022.................................................................................
Change in fair value .............................................................................................
Balance, September 30, 2023.................................................................................

Series 1
Nonconvertible
Preferred
Stock
(in thousands)

1,479
27
1,506
(83)
1,423
—
1,423

In April 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was
paid a $200,000 cash purchase price in exchange for 54.5% of future quarterly royalty payments on net sales of
MAVYRET/MAVIRET, after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the
purchase price. The Company accounted for the upfront payment as a liability related to the sale of future royalties. The carrying value
of the liability related to the sale of future royalties approximates fair value as of September 30, 2023 and is based on current estimates
of future royalties expected to be paid to OMERS over the next 10 years, which are considered Level 3 inputs. See Note 8 for a
rollforward of the liability.

4. Marketable Securities

As of September 30, 2023 and 2022, the fair value of available-for-sale marketable securities, by type of security, was as follows:

Amortized
Cost

Gross
Unrealized
Gains

September 30, 2023
Gross
Unrealized
Losses
(in thousands)

Credit
Losses

Fair Value

Corporate bonds....................................................... $
Commercial paper....................................................
U.S. Treasury notes..................................................

27,127 $
21,305
236,880
$ 285,312 $

— $
—
12
12 $

(692) $
—
(110)
(802) $

26,435
— $
21,305
—
—
236,782
— $ 284,522

Amortized
Cost

Gross
Unrealized
Gains

September 30, 2022
Gross
Unrealized
Losses
(in thousands)

Credit
Losses

Fair Value

Corporate bonds ......................................................... $
Commercial paper ......................................................
U.S. Treasury notes ....................................................

78,663 $
66,784
92,416
$ 237,863 $

— $
—
—
— $

(2,252) $
—
(1,088)
(3,340) $

76,411
— $
66,784
—
—
91,328
— $ 234,523

As of September 30, 2023, marketable securities consisted of investments that mature within one year. As of September 30, 2022,
marketable securities consisted of investments that mature within one year, with the exception of certain corporate bonds and U.S.
treasury notes, which have maturities between one and three years and an aggregate fair value of $29,285.

F-15

5. Property and Equipment, Net

Property and equipment, net consisted of the following as of September 30, 2023 and 2022:

Laboratory and office equipment............................................................................. $
Leasehold improvements .........................................................................................
Purchased software ..................................................................................................
Furniture...................................................................................................................
Computer equipment................................................................................................
Construction in progress ..........................................................................................

Less: Accumulated depreciation and amortization ..................................................

September 30,

2023

2022

(in thousands)

15,891
13,804
1,444
2,290
962
1,273
35,664
(23,745)
11,919

14,780
7,276
1,412
1,354
653
2,556
28,031
(21,858)
6,173

As of September 30, 2023, construction in progress related primarily to leasehold improvements. Depreciation and amortization
expense for property and equipment, was $2,371, $2,973 and $3,334 for the years ended September 30, 2023, 2022, and 2021,
respectively.

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of September 30, 2023 and 2022:

Accrued pharmaceutical drug manufacturing............................................................ $
Accrued research and development expenses............................................................
Accrued payroll and related expenses .......................................................................
Accrued other.............................................................................................................

September 30,

2023

2022

(in thousands)
3,083 $
6,120
7,037
2,099
18,339 $

6,932
5,532
6,439
2,033
20,936

7. Collaboration Agreements

AbbVie Collaboration

The Company has a Collaborative Development and License Agreement (as amended, the “AbbVie Agreement”), with AbbVie to
identify, develop and commercialize HCV NS3 and NS3/4A protease inhibitor compounds, including paritaprevir and glecaprevir,
under which the Company has received license payments, proceeds from a sale of preferred stock, research funding payments,
milestone payments and royalties totaling approximately $1,287,000 through September 30, 2023. Since the Company satisfied all of
its performance obligations under the AbbVie Agreement by the end of fiscal 2011, all milestone payments received since then have
been recognized as revenue when the milestones were achieved by AbbVie.

The Company is receiving annually tiered royalties per Company protease product ranging from ten percent up to twenty percent, or
on a blended basis from ten percent up to the high teens, on the portion of AbbVie’s calendar year net sales of each HCV regimen that
is allocated to the protease inhibitor in the regimen. Beginning with each January 1, the cumulative net sales of a given royalty-bearing
protease inhibitor product start at zero for purposes of calculating the tiered royalties on a product-by-product basis. The following
table details the royalty tiers associated with cumulative calendar year net sales allocated to each royalty-bearing product as provided
in the AbbVie Agreement:

Calendar Year Net Sales
(in thousands)

up to $500,000
from $500,000 up to $750,000
from $750,000 up to $1,000,000
from $1,000,000 up to $2,500,000
greater than or equal to $2,500,000

Royalty Tier
(%)
10%
12%
14%
17%
20%

F-16

Royalties owed to the Company under the agreement can be reduced by AbbVie in certain circumstances, including (i) if AbbVie
exercises its right to license or otherwise acquire rights to intellectual property controlled by a third party where a product could not be
legally developed or commercialized in a country without the third-party intellectual property right, (ii) where a product developed
under the collaboration agreement is sold in a country and not covered by a valid patent claim in such country, and (iii) where sales of
a generic product are equal to at least a specified percentage of AbbVie’s market share of its product in a country.

AbbVie’s obligation to pay royalties on a product developed under the agreement expires on a country-by-country basis upon the later
of (i) the date of expiration of the last of the licensed patents with a valid claim covering the product in the applicable country, or (ii)
ten years after the first commercial sale of the product in the applicable country.

Subject to certain exceptions, a party’s rights and obligations under the agreement continue until (i) such time as AbbVie is no longer
developing a product candidate or (ii) if, as of the time AbbVie is no longer developing any product candidates, AbbVie is
commercializing any other protease inhibitor product, such time as all royalty terms for all covered products have ended. Accordingly,
the final expiration date of the agreement is currently indeterminable.

If the Company terminates the agreement for cause or AbbVie terminates without cause, any licenses and other rights granted to
AbbVie will terminate and AbbVie will be deemed to have granted the Company (i) a non-exclusive, perpetual, fully-paid, worldwide,
royalty-free license, with the right to sublicense, under AbbVie’s intellectual property used in any product candidate, and (ii) an
exclusive (even as to AbbVie), perpetual, fully-paid, worldwide, royalty-free license, with the right to sublicense, under AbbVie’s
interest in any joint intellectual property rights to develop product candidates resulting from covered compounds and to commercialize
any products derived from such compounds. Upon the Company’s request, AbbVie will also transfer to the Company all right, title
and interest in any related product trademarks, regulatory filings and clinical trials.

If AbbVie terminates the agreement for the Company’s uncured breach, the milestone and royalty payments payable by AbbVie may
be reduced, the licenses granted to AbbVie will remain in place, the Company will be deemed to have granted AbbVie an exclusive
license under the Company’s interest in joint intellectual property, AbbVie will continue to have the right to commercialize any
covered products, and all rights and licenses granted to the Company by AbbVie will terminate.

8. Liability Related to the Sale of Future Royalties

Because the royalty sale agreement will be paid back to OMERS up to a capped amount as well as the Company’s significant
continuing involvement in the generation of future cash flows under its AbbVie Agreement, the Company recorded the proceeds from
the transaction as a liability on its consolidated balance sheets which will be amortized as interest expense in the consolidated
statements of operations under the effective interest rate method over the life of the royalty sale agreement. The Company will
continue to record the full amount of royalties earned on MAVYRET/MAVIRET sales as royalty revenue in the consolidated
statements of operations.

The Company’s liability related to the sale of future royalties is estimated based on forecasted worldwide MAVYRET/MAVYRET
royalties to be paid to OMERS over the course of the royalty sale agreement. This estimate requires significant judgment, including
the amount and timing of royalty payments up until the end of the royalty sale agreement, which is estimated to be the stated term of
June 30, 2032. As royalties are earned by OMERS, the liability is reduced on the Company’s consolidated balance sheets.

At September 30, 2023, the estimated future cash flows resulted in an effective annual imputed interest rate of approximately 6.18%.
The following table summarizes the activity of the liability related to the sale of future royalties:

Balance - September 30, 2022 .................................................................................................... $
Proceeds from sale of future royalties ......................................................................................
Debt issuance cost.....................................................................................................................
Royalty payable to royalty purchaser .......................................................................................
Non-cash interest expense ........................................................................................................
Balance - September 30, 2023 .................................................................................................... $

—
200,000
(325)
(10,318)
5,148
194,505

Liability related to the sale of future
royalties
(in thousands)

F-17

9. Stockholders’ Equity

The Company is authorized to issue 100,000 shares of common stock at a par value of $0.01 per share. Each share of common stock
entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to
receive such dividends as may be declared by the board of directors, if any.

The Company also is authorized to issue 5,000 shares of preferred stock at a par value of $0.01 per share, of which 2,000 shares are
designated as Series 1 Nonconvertible preferred stock and 3,000 shares are undesignated and unissued.

10. Series 1 Nonconvertible Preferred Stock

The Company’s Certificate of Incorporation authorizes the issuance of up to 2,000 shares of Series 1 nonconvertible preferred stock at
a par value of $0.01 per share. Holders of Series 1 nonconvertible preferred stock are not entitled to receive dividends. In the event of
any liquidation, deemed liquidation, dissolution or winding up of the Company, the Series 1 nonconvertible preferred stockholders are
entitled to receive in preference to all other stockholders, an amount equal to $1.00 per share, adjusted for any stock dividends, stock
splits or reclassifications. Series 1 nonconvertible preferred stockholders will not be entitled to vote unless required by the Company
pursuant to the laws of the State of Delaware. The Company may redeem the Series 1 nonconvertible preferred stock with the
approval of the holders of a majority of the outstanding shares of Series 1 nonconvertible preferred stock at a redemption price of
$1.00 per share. The Company must redeem the stock within 60 days of such election. Shares that are redeemed will be retired or
canceled and not reissued by the Company. As these shares qualify as a derivative, they are classified as a liability on the Company’s
consolidated balance sheet.

As of September 30, 2023 and 2022, 1,930 shares of Series 1 nonconvertible preferred stock were issued and outstanding. For the
years ended September 30, 2023, 2022, and 2021, the remeasurement of the Series 1 nonconvertible preferred stock resulted in income
(expense) of $0, $83, and $(27), respectively, which was recorded in other income (expense) in the consolidated statements of
operations. The total fair value of the Series 1 nonconvertible preferred stock was $1,423 as of September 30, 2023 and 2022.

11. Stock-Based Awards

The Company grants stock-based awards, including stock options, restricted stock units and other unit awards under its 2019 Equity
Incentive Plan (the “2019 Plan”), which was approved by its stockholders on February 28, 2019 and amended in March 2021, March
2022, and March 2023. The Company also has outstanding stock option awards under its 2012 Equity Incentive Plan (the “2012
Plan”), but is no longer granting awards under this plan. The Company’s 2019 Plan permits the Company to sell or issue awards of
common stock or restricted common stock or to grant awards of incentive stock options or nonqualified stock options for the purchase
of common stock, restricted stock units, performance units, stock appreciation rights or other cash incentive awards, to employees,
members of the board of directors and consultants of the Company. The number of shares of common stock that may be issued under
the 2019 Plan is subject to increase by the number of shares forfeited under any options forfeited and not exercised under the 2019
Plan or any predecessor plans such as the 2012 Plan. As of September 30, 2023, 1,535 shares remained available for future awards
under the 2019 Plan.

Under the Company’s Employee Stock Purchase Plan (“ESPP”) a total of 186 shares of common stock are reserved for issuance. As of
September 30, 2023, the Company had not commenced any offering under the ESPP and no ESPP shares have been issued.

Options granted under the 2019 Plan to employees generally vest over four years and to non-employee directors over one year, and
expire after ten years. As required under the equity plans, the exercise price for awards granted is not to be less than the fair value of
common shares on the date of grant. Restricted stock units with service-based vesting conditions generally vest over four years.

Stock Option Valuation

The fair value of each stock option award is determined on the date of grant using the Black-Scholes option-pricing model. The
volatility has been determined using the Company’s traded stock price to estimate expected volatility. The expected term of the
Company’s options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-
free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods
approximately equal to the expected term of the award. The expected dividend yield is zero due to the fact that the Company has never
paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The relevant data used to determine the
value of the stock option awards are as follows, presented on a weighted average basis:

Risk-free interest rate..............................................................
Expected term (in years).........................................................
Expected volatility ..................................................................
Expected dividends.................................................................
Weighted average grant date fair value .................................. $

F-18

2023

Years Ended September 30,
2022

2021

3.88%
6.04

48%
0%

1.72%
6.04

47%
0%

22.71

33.22

0.61%
6.05

52%
0%

21.76

The following table summarizes stock option activity, including aggregate intrinsic value for the year ended September 30, 2023:

Shares
Issuable
Under
Options
(in thousands)

Weighted
Average
Exercise
Price

Weighted
Average
Remaining
Contractual
Term in years

Outstanding as of September 30, 2022 .................
Granted .................................................................
Exercised ..............................................................
Forfeited ...............................................................
Outstanding as of September 30, 2023 .................
Options vested and expected to vest as of

September 30, 2023..............................................
Options exercisable as of September 30, 2023 .....

3,993
765
(124)
(269)
4,365

4,365
3,086

$
$

53.57
44.47
17.83
58.64
52.68

52.68
52.20

6.2

5.9

5.9
4.9

Aggregate
Intrinsic
Value
(in thousands)
28,778
$

$
$

—

—
—

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of
the Company’s common stock. The following tables summarize additional exercise and grant date information:

2023

Years Ended September 30,
2022
(in thousands)

2021

Aggregate intrinsic value of stock options exercised ............. $
Proceeds to Company from stock options exercised .............. $

3,295
2,208

$
$

17,650
21,262

$
$

2,704
3,614

Market and Performance-Based Stock Unit Awards

The Company awards both performance share units (“PSUs”) and relative total stockholder return units (“rTSRUs”) to its executive
officers.

The PSUs vest and result in issuance, or settlement, of common shares for each recipient, based upon the recipient’s continued
employment with the Company through the settlement date of the award and the Company’s achievement of specified research and
development milestones. The requisite service period of the PSUs is generally two years. The fair value of PSUs is based on the fair
value of the stock on the date of grant, which is determined to be the closing price of the Company's common stock. Stock-based
compensation expense for PSUs is recorded in the statements of operations over the service period, commencing when it is probable
that the specified research and development milestone is achieved.

The rTSRUs vest and result in the issuance of common stock based upon the recipient’s continuing employment with the Company
through the settlement date of the award and the relative ranking of the total stockholder return, or TSR, of the Company’s common
stock in relation to the TSR of the component companies in the NASDAQ Biotech Index over two specified periods that are two years
apart, based on a comparison of average closing stock prices in specified periods noted in the award agreement. The number of
market-based rTSRUs awarded represents the target number of shares of common stock that may be earned; however, the actual
number of shares that may be earned ranges from 0% to 150% of the target number, depending on the award agreement and the year
of the award. The Company used a Monte Carlo model to estimate the grant-date fair value of the rTSRUs. Stock-based compensation
expense for rTSRUs is recorded in the statements of operations over the service period regardless of whether the market condition is
achieved.

Assumptions and estimates utilized in the calculation of the fair value of the rTSRUs include the risk-free interest rate, dividend yield,
expected volatility based on the historical volatility of publicly traded peer companies and the remaining performance period of the
award. The table below sets forth the weighted average grant date fair value assumptions used to value the rTSRUs:

Risk-free interest rate..............................................................
Dividend yield ........................................................................
Expected volatility ..................................................................
Performance period (years).....................................................

4.19%
0%
77%

2.03

0.94%
0%
80%

1.97

0.13%
0%
74%

1.97

2023

Years Ended September 30,
2022

2021

F-19

The following table summarizes PSU and rTSRU activity (at target) for the year ended September 30, 2023:

PSUs

rTSRUs

Unvested at September 30, 2022 ...........................
Granted ...................................................................
Vested.....................................................................
Cancelled ................................................................
Unvested at September 30, 2023 ...........................

101
50
(70)
—
81

Weighted
Average
Grant
Date Fair
Value per
Share

(in thousands, except per share data)
101
$
50
(70)
—
81

54.50
47.24
44.58
—
58.58

Weighted
Average
Grant
Date Fair
Value per
Share

36.14
40.32
27.88
—
45.82

The total fair value of PSUs and rTSRUs vested during the years ended September 30, 2023, 2022, and 2021 were $8,103, $1,414 and
$0, respectively.

Restricted Stock Units

The following table summarizes the restricted stock unit activity for the year ending September 30, 2023:

Unvested at September 30, 2022.............................................................
Granted.....................................................................................................
Vested ......................................................................................................
Cancelled .................................................................................................
Unvested at September 30, 2023.............................................................

Weighted
Average Grant
Date Fair
Value per
Share
(in thousands, except per share data)

Restricted
Stock
Units

219
280
(61)
(27)
411

64.03
44.63
61.94
53.98
51.78

The total fair value of restricted stock units vested during the years ended September 30, 2023, 2022, and 2021 were $2,590, $2,427
and $1,897, respectively.

Stock-Based Compensation Expense

The Company recorded the following stock-based compensation expense for the years ended September 30, 2023, 2022, and 2021:

Research and development ..................................................... $
General and administrative .....................................................

Stock options .......................................................................... $
rTSRUs ...................................................................................
PSUs .......................................................................................
Restricted stock units..............................................................

2023

Years Ended September 30,
2022
(in thousands)

2021

9,551
18,665
28,216

9,728
17,241
26,969

10,075
10,916
20,991

2023

Years Ended September 30,
2022
(in thousands)

2021

19,784
1,893
542
5,997
28,216

19,615
1,597
2,628
3,129
26,969

18,004
1,537
235
1,215
20,991

As of September 30, 2023, the Company had an aggregate of $61,333 of unrecognized stock-based compensation cost, which is
expected to be recognized over a weighted average period of 2.2 years.

F-20

12. Leases

The Company has two real estate leases for properties located in Watertown, Massachusetts. The first lease, for office and laboratory
space at 500 Arsenal Street and expires in September 2027. The second lease, for office space located at 400 Talcott Avenue and
expires in June 2034.

Lease payments for the Company's real estate leases include fixed lease payments that escalate over the terms of the leases and require
the Company to pay certain operating expenses based on actual costs incurred. Operating expenses that are not fixed in nature are
expensed in the period incurred and included in variable lease costs. The leases do not include any restrictions or covenants that had to
be accounted for under the lease guidance.

In May 2022, the Company entered into a new ten-year lease agreement with its existing landlord for laboratory and office space in
Watertown, Massachusetts, adjacent to its 400 Talcott Avenue premises to accommodate its growing headcount. The new lab and
office space will be located at Arsenal on the Charles in Watertown, Massachusetts, at a to-be-constructed facility. The Company
expects to gain access to the space to perform tenant improvements beginning in December 2023. The estimated minimum lease
payments as a result of the new lease total $76,470 over the ten-year term. The lease also contains a tenant improvement allowance of
$15,194. The Company will account for the lease as a right-of-use asset and lease liability upon the lease commencement date.

In conjunction with the new lease agreement at Arsenal on the Charles, the Company amended its 500 Arsenal Street lease to shorten
the term of the lease from September 2027 to the date when the Arsenal on the Charles facility is completed and ready for the
Company's occupancy. The construction of the Arsenal on the Charles facility is being conducted by the landlord and it is expected
that the facility will be ready for the Company's tenant improvement buildout in December 2023. As the construction of the facility
and the timing of completion is not in the control of the Company, the Company will remeasure the term for the 500 Arsenal Street
lease for financial accounting purposes at the time the contingency regarding occupancy lapses.

The Company leases units of equipment over eighteen-month lease periods commencing upon shipment of each unit. The lease
agreements contain options to terminate the leases early or to extend the leases for successive six-month periods, however these
options were not included in the right-of-use assets and lease liability as they were not reasonably certain of being exercised. The
equipment leases require the Company to pay for certain consumable and peripheral equipment supplies based on actual costs
incurred. As these costs are not fixed in nature, they are expensed in the period incurred and included in variable lease costs.

The components of lease expense for the Company’s real estate and equipment leases were as follows:

Operating lease cost................................................................................................... $
Variable lease cost .....................................................................................................

2023

Years Ended September 30,
2022
(in thousands)

2021

6,230
5,352
11,582

6,294
2,375
8,669

5,861
4,057
9,918

Supplemental disclosure of cash flow information related to the Company's operating leases included in cash flows used in operating
activities in the consolidated statements of cash flows were as follows:

2023

Years Ended September 30,
2022
(in thousands)

2021

Cash paid for amounts included in the measurement of operating lease liabilities .. $
Operating lease liabilities arising from obtaining right-of-use assets ....................... $

4,592
3,817

$
$

4,966
23,910

$
$

6,364
3,320

The weighted-average remaining lease term and discount rate were as follows:

Weighted-average remaining lease term - operating leases (in years) .......................................
Weighted-average discount rate - operating leases ....................................................................

6.51
7.18%

7.42
6.96%

As the Company’s leases do not provide an implicit rate, the Company utilized its incremental borrowing rate based on information
available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a
collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment.

September 30,

2023

2022

F-21

Future annual minimum lease payments relating to the Company's lease liabilities as of September 30, 2023 were as follows:

Years ended September 30,
2024 .......................................................................................................................................................
2025 .......................................................................................................................................................
2026 .......................................................................................................................................................
2027 .......................................................................................................................................................
2028 .......................................................................................................................................................
Thereafter...............................................................................................................................................
Total future minimum lease payments ..................................................................................................
Less: imputed interest ............................................................................................................................
Total operating lease liabilities .............................................................................................................. $

(in thousands)

6,734
5,314
5,373
5,196
1,640
10,273
34,530
(8,017)
26,513

Included in the balance sheet:

September 30,

2023

2022

(in thousands)

Current operating lease liabilities ................................................................................. $
Operating lease liabilities, net of current portion .........................................................
Total operating lease liabilities..................................................................................... $

5,275 $

21,238
26,513 $

2,891
22,372
25,263

The tables above do not include lease payments related to the Company’s Arsenal on the Charles facility because as of September 30,
2023, the lease commencement date had not occurred. Additionally, the tables above do not include the impact of shortening the term
for the 500 Arsenal Street Lease as the term date is contingent upon events not in the Company's control.

The Company is required to maintain security deposits of $652 in connection with various of its real estate leases, which amounts are
included in other long-term assets on the Company's consolidated balance sheets. In addition, the Company is required to maintain
letters of credit for certain of its leases, collateralized by money market accounts of $3,968, which amounts are classified as long-term
restricted cash on the consolidated balance sheets.

13. Commitments and Contingencies

Litigation and Contingencies Related to Use of Intellectual Property

From time to time, the Company may become subject to legal proceedings, claims and litigation arising in the ordinary course of
business. Except as described below, the Company currently is not a party to any threatened or pending litigation. However, third
parties might allege that the Company or its collaborators are infringing their patent rights or that the Company is otherwise violating
their intellectual property rights. Such third parties may resort to litigation against the Company or its collaborators, which the
Company has agreed to indemnify. With respect to some of these patents, the Company expects that it will be required to obtain
licenses and could be required to pay license fees or royalties, or both. These licenses may not be available on acceptable terms, or at
all. A costly license, or inability to obtain a necessary license, would have a material adverse effect on the Company’s financial
condition, results of operations or cash flows. The Company accrues contingent liabilities when it is probable that future expenditures
will be made and such expenditures can be reasonably estimated.

In June 2022, the Company announced that it filed suit in the United States District Court for the District of Massachusetts on June 21,
2022, against Pfizer, Inc. seeking damages for infringement of U.S. Patent No. 11,358,953 (the ’953 Patent) in the manufacture, use
and sale of Pfizer’s COVID-19 antiviral, Paxlovid™ (nirmatrelvir tablets; ritonavir tablets). The United States Patent and Trademark
Office awarded the '953 Patent to the Company in June 2022 based on the Company's July 2020 patent application describing
coronavirus protease inhibitors invented by the Company. The Company is seeking fair compensation for Pfizer’s use of a coronavirus
protease inhibitor claimed in the ‘953 patent. The Company records all legal expenses associated with the patent infringement suit as
incurred in the consolidated statements of operations.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to customers, vendors,
lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of
such agreements or from services to be provided to the Company, or from intellectual property infringement claims made by third
parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive
officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of
their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to
make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs
as a result of such indemnifications. In addition, the Company maintains directors’ and officers’ insurance coverage. The Company

F-22

does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial
position, results of operations or cash flows, and has not accrued any liabilities related to such obligations in its consolidated financial
statements as of September 30, 2023 and 2022.

14. Income Taxes

Income before income taxes for all periods presented is from domestic operations, which are the Company’s only operations. During
the years ended September 30, 2023, 2022, and 2021, the Company recorded income tax (expense) benefit as follows:

2023

Years Ended September 30,
2022
(in thousands)

2021

Current income tax (expense) benefit:

Federal ............................................................................................... $
State ...................................................................................................

(2,522) $
(299)

Deferred income tax (expense) benefit:

Federal ...............................................................................................
State ...................................................................................................
Income tax (expense) benefit ................................................................ $

—
—
(2,821) $

— $
449

(16)
—
433

28,721
205

(343)
—
28,583

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective tax rate is as follows:

Federal statutory income tax rate ......................................................
State taxes, net of federal benefit ..................................................
Change in valuation allowance .....................................................
Federal research and development tax credit ................................
Share-based compensation ............................................................
State research and development tax credit ....................................
Foreign derived intangible income ...............................................
Change in deferred tax rate ...........................................................
Other..............................................................................................
Effective income tax rate ..................................................................

2023

Years Ended September 30,
2022

2021

(21.0) %
(2.7)
36.6
(4.6)
2.2
(0.9)
(7.0)
(0.1)
(0.3)
2.2 %

(21.0) %
(2.9)
30.8
(4.6)
(0.8)
(1.5)
—
(0.1)
(0.3)
(0.4) %

(21.0) %
(2.3)
9.9
(5.3)
2.4
(0.8)
—
(9.5)
—
(26.6) %

The effective tax rates during the years ended September 30, 2023 and 2022 differ from the U.S. federal statutory rate primarily due to
the full valuation allowance maintained on the Company’s net deferred tax assets.

Changes in the valuation allowance for deferred tax assets during the years ended September 30, 2023, 2022, and 2021 are as follows:

Valuation allowance, beginning of year ............................................ $
Increase recorded to valuation allowance ...........................................
Valuation allowance, end of year ....................................................... $

(67,726) $
(47,394)
(115,120) $

(29,298) $
(38,428)
(67,726) $

(18,259)
(11,039)
(29,298)

2023

Years Ended September 30,
2022
(in thousands)

2021

F-23

Net deferred tax assets as of September 30, 2023 and 2022 consisted of the following:

September 30,

2023

2022

(in thousands)

Deferred tax assets:

Share-based compensation................................................................................... $
Tax credit carryforwards......................................................................................
Capitalized research and development.................................................................
Liability related to the sale of future royalties .....................................................
Operating lease liability .......................................................................................
Accrued compensation.........................................................................................
Net operating loss carryforward...........................................................................
Unrealized loss.....................................................................................................
Accrued expenses.................................................................................................
Other temporary differences ................................................................................
Total deferred tax assets...................................................................................
Valuation allowance.............................................................................................
Net deferred tax assets .........................................................................................

16,974
15,549
34,855
46,560
6,485
1,318
43
189
495
214
122,682
(115,120)
7,562

Deferred tax liabilities:

Operating lease, right-of-use assets .................................................................
Depreciation .....................................................................................................
Prepaid expenses ..............................................................................................
Total deferred tax liabilities .................................................................................
Net deferred income tax assets (liabilities) .............................................................. $

(1,525)
(5,456)
(581)
(7,562)

— $

14,983
20,663
—
—
6,007
1,362
29,105
794
541
245
73,700
(67,726)
5,974

(5,606)
(88)
(280)
(5,974)
—

As of September 30, 2023, the Company did not have federal net operating loss carryforwards. As of September 30, 2023, the
Company had state net operating loss carryforwards of $702, which may be available to offset future taxable income and expires in
2032. As of September 30, 2023, the Company also had federal and state research and development tax credit carryforwards of
$11,377 and $6,035, respectively, which may be available to reduce future tax liabilities and expire at various dates beginning in 2042
and 2035, respectively.

Utilization of the federal and state net operating loss carryforwards and research and development tax credit carryforwards may be
subject to a substantial annual limitation under Sections 382 and 383 of the Internal Revenue Code ("IRC") of 1986, and
corresponding provisions of state law, due to ownership changes that may have occurred previously or that could occur in the future.
These ownership changes may limit the amount of net operating loss and research and development tax credit carryforwards that can
be utilized annually to offset future tax liabilities. In general, an ownership change, as defined by Section 382, results from
transactions that increase the ownership of 5% stockholders in the stock of a corporation by more than 50% in the aggregate over a
three-year period. The Company completed a review of the changes in ownership through September 30, 2022 and determined that the
transactions have not resulted in an ownership change during the year ended September 30, 2022, as defined by Section 382. The
impact of the historical ownership changes have been reflected within our deferred tax assets shown in the table above. Although the
Company believes that these ownership changes have not resulted in material limitations on its ability to use these net operating losses
and credit carryforwards, its ability to utilize these and future net operating losses and credit carryforwards may be limited due to
future ownership changes or for other reasons. As a result, the Company may not be able to take full advantage of its carryforwards
for U.S. federal and state tax purposes.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets, which are
comprised primarily of net operating loss carryforwards, research and development tax credit carryforwards and stock compensation
expense. The Company considers it more likely that it will not have sufficient taxable income in the future that will allow it to realize
all of its existing deferred tax assets. This is due to the fact the Company continues to progress its wholly-owned research and
development programs and its declining royalty revenues from its Collaboration Agreement with AbbVie. As a result, the Company
continued to record a valuation allowance as of September 30, 2023 against its deferred tax assets to reduce a portion of the
Company’s deferred tax assets for which the Company does not believe it is more likely than not these will be realized.

The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business,
the Company is subject to examination by federal and state jurisdictions, where applicable. The Company’s tax years in the U.S. are
still open under statute from 2020 to the present. Earlier years may be examined to the extent that tax credit or net operating loss
carryforwards are used in future periods. The Company has not received notice of examination by any jurisdiction for any tax year
open under statute.

F-24

Beginning in October 1, 2022, the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) eliminated the Company’s option to deduct research
and development expenditures currently and requires taxpayers to amortize them over five years for domestic research expenditures
and over fifteen years for foreign research expenditures, pursuant to IRC 174. The most significant impact of this provision is an
increase to the current taxable income for the year ended September 30, 2023, the tax year in which the provision took effect for the
Company.

In response to the COVID-19 pandemic, the CARES Act was signed into law in March 2020. The CARES Act lifted certain deduction
limitations originally imposed by the Tax Act. Under the CARES Act, the Company was permitted to carryback net operating losses
for up to five years for losses generated in fiscal 2018 through fiscal 2021. Net operating loss carrybacks were previously prohibited
under the Tax Act. The CARES Act also eliminated the 80% of taxable income limitations by allowing corporate entities to fully
utilize net operating loss carryforwards to offset taxable income in fiscal years 2018, 2019 or 2020. In addition, the CARES Act made
qualified improvement property eligible for 15-year cost-recovery and 100% bonus depreciation. The enactment of the CARES Act
resulted in a $28,721 income tax benefit related to a federal net operating loss carryback at the previously enacted 35% rate in the
Company’s consolidated financial statements during the year ended September 30, 2021. As of September 30, 2023 and 2022, the
Company had an income tax receivable of $31,004 and $28,718, respectively, which includes interest receivable of $1,390 as of
September 30, 2023.

Uncertain tax positions represent tax positions for which reserves have been established. The Company’s policy is to record interest
and penalties related to uncertain tax positions as part of income tax expense. Total interest related to uncertain tax positions recorded
as a liability on the Company’s consolidated balance sheets were $3 and $44 as of September 30, 2023 and 2022, respectively. A
reconciliation of the beginning and ending amount of uncertain tax positions is summarized as follows:

September 30,

2023

2022

Beginning Balance...................................................................................................... $
Additions based on tax positions for the current period ..........................................
Reductions for tax positions due to lapse of statute of limitations ..........................
Additions (reductions) for tax positions of prior periods ........................................
Ending Balance .......................................................................................................... $

(in thousands)
226
882
(156)
104
1,056

622
10
(367)
(39)
226

The Company does not expect that its uncertain tax position will materially change within the next twelve months.

15. 401(k) Plan

The Company has a 401(k) plan. This plan covers substantially all employees who meet minimum age and service requirements.
During the years ended September 30, 2023, 2022, and 2021, the Company recognized $1,784, $1,596, and $1,353, respectively, of
expense related to its contributions to this plan.

F-25

Corporate Headquarters
Enanta Pharmaceuticals, Inc.
500 Arsenal Street
Watertown, MA 02472

Investor Inquiries
Investor Inquiries (including requests for a
copy of Enanta’s Annual Report on Form 10-K,
available free of charge) should be directed to:

Enanta Pharmaceuticals, Inc.
500 Arsenal Street
Watertown, MA 02472
Attention: Investor Relations
Phone: 617-607-0800
Email: ir@enanta.com

The 2023 Annual Report on Form 10-K and
other investor information are available in
the Investors section of Enanta’s website at
www.enanta.com.

Independent Registered Public
Accounting Firm
PricewaterhouseCoopers LLP
101 Seaport Boulevard, Suite 500
Boston, MA 02210

Corporate Counsel
Foley Hoag LLP
Seaport West
155 Seaport Boulevard
Boston, Massachusetts 02210

Transfer Agent
Computershare Investor Services
462 South 4th Street, Suite 1600
Louisville, KY 40202

Stock Listing
NASDAQ Global Select Market: ENTA

Web Site
www.enanta.com

MANAGEMENT TEAM

Jay R. Luly, Ph.D.

President, Director and Chief Executive Officer

Nathaniel S. Gardiner, J.D.

Chief Legal Officer and Corporate Secretary

Tara L. Kieffer, Ph.D.

Chief Product Strategy Officer

Brendan Luu

Chief Business Officer

Paul J. Mellett

Chief Financial and Administrative Officer

Yat Sun Or, Ph.D.

Chief Scientific Officer

Scott T. Rottinghaus, M.D.
Chief Medical Officer

BOARD OF DIRECTORS

Bruce L. A. Carter, Ph.D.

Non-Executive Chairman of the Board,
Enanta Pharmaceuticals, Inc.
Former President and Chief Executive Officer,
ZymoGenetics, Inc.

Mark G. Foletta

Former Chief Financial Officer,
Amylin Pharmaceuticals, Inc.,
and other companies

Yujiro S. Hata

Founder and Chief Executive Officer,
IDEAYA Biosciences, Inc.

Jay R. Luly, Ph.D.

President and Chief Executive Officer,
Enanta Pharmaceuticals, Inc.

Kristine Peterson

Former Chief Executive Officer, Valeritas, Inc.

Lesley Russell, MBChB, MRCP

Former Chief Medical Officer, Cephalon, Inc.,
and other companies

Terry C. Vance

Private consultant and former biotechnology
venture capital investor

Enanta Pharmaceuticals, Inc.
500 Arsenal Street
Watertown, MA 02472