ENANTA PHARMACEUTICALS INC (ENTA)

CIK: 0001177648. SIC: 2834 Pharmaceutical Preparations. Latest 10-K as of: 2025-11-19.

SIC breadcrumb: Manufacturing > Chemicals And Allied Products > SIC 2834 Pharmaceutical Preparations

SEC company page: https://www.sec.gov/edgar/browse/?CIK=1177648. Latest filing source: 0001193125-25-288121.

Selected Fundamentals

Financials

Annual standardized facts from SEC companyfacts as of latest extracted filing date 2025-11-19. Source: https://data.sec.gov/api/xbrl/companyfacts/CIK0001177648.json. Derived margins, ratios, and free cash flow are computed from the extracted annual SEC facts.

Flow metrics use full-year FY periods from 10-K/10-K/A filings; balance-sheet metrics use FY-end instants. Free cash flow = operating cash flow - capital expenditures. Missing metrics are omitted rather than fabricated.

Ratios

ROE and ROA use period-end equity/assets. Liabilities / equity uses total liabilities divided by stockholders' equity. Current ratio uses current assets divided by current liabilities when both are reported.

Financial Charts

Quarterly

Quarterly standardized facts from SEC companyfacts as of latest extracted filing date 2026-05-13. Source: https://data.sec.gov/api/xbrl/companyfacts/CIK0001177648.json.

Flow metrics use discrete quarter-length periods from 10-Q/10-Q/A filings. Q4 revenue and net income are derived only when annual FY and nine-month YTD facts exist for the same fiscal year; derived Q4 values are labeled. EPS Q4 is not derived.

Quarterly Charts

Macro Cross-References

• CPIAUCSL - Consumer Price Index for All Urban Consumers: All Items in U.S. City Average
• UNRATE - Unemployment Rate
• FEDFUNDS - Federal Funds Effective Rate
• CES0500000003 - Average Hourly Earnings of All Employees, Total Private
• DFEDTARU - Federal Funds Target Range - Upper Limit
• DFEDTARL - Federal Funds Target Range - Lower Limit
• DGS3MO - Market Yield on U.S. Treasury Securities at 3-Month Constant Maturity
• DGS2 - Market Yield on U.S. Treasury Securities at 2-Year Constant Maturity
• DGS10 - Market Yield on U.S. Treasury Securities at 10-Year Constant Maturity
• DGS30 - Market Yield on U.S. Treasury Securities at 30-Year Constant Maturity
• T10Y2Y - 10-Year Treasury Constant Maturity Minus 2-Year Treasury Constant Maturity
• CPILFESL - Consumer Price Index for All Urban Consumers: All Items Less Food and Energy
• CPIUFDSL - Consumer Price Index for All Urban Consumers: Food
• CPIENGSL - Consumer Price Index for All Urban Consumers: Energy
• CUSR0000SAH1 - Consumer Price Index for All Urban Consumers: Shelter
• PCEPI - Personal Consumption Expenditures: Chain-type Price Index
• PCEPILFE - Personal Consumption Expenditures Excluding Food and Energy: Chain-type Price Index
• PPIACO - Producer Price Index by Commodity: All Commodities
• T10YIE - 10-Year Breakeven Inflation Rate
• U6RATE - Total Unemployed, Plus All Marginally Attached Workers Plus Total Employed Part Time for Economic Reasons
• PAYEMS - All Employees, Total Nonfarm
• CIVPART - Labor Force Participation Rate
• EMRATIO - Employment-Population Ratio
• UNEMPLOY - Unemployed
• CE16OV - Employment Level
• ICSA - Initial Claims
• JTSJOL - Job Openings: Total Nonfarm
• JTSQUR - Quits: Total Nonfarm
• GDPC1 - Real Gross Domestic Product
• A191RL1Q225SBEA - Real Gross Domestic Product: Percent Change from Preceding Period
• INDPRO - Industrial Production: Total Index
• TCU - Capacity Utilization: Total Index
• HOUST - New Privately-Owned Housing Units Started: Total Units
• PERMIT - New Privately-Owned Housing Units Authorized in Permit-Issuing Places: Total Units
• RSAFS - Advance Retail Sales: Retail Trade
• PCE - Personal Consumption Expenditures
• DSPIC96 - Real Disposable Personal Income
• PSAVERT - Personal Saving Rate
• M2SL - M2
• BOPGSTB - U.S. International Trade in Goods and Services: Balance
• MSPUS - Median Sales Price of Houses Sold for the United States
• HSN1F - New One Family Houses Sold: United States
• RHORUSQ156N - Homeownership Rate in the United States
• TTLCONS - Total Construction Spending: Total Construction in the United States
• RRVRUSQ156N - Rental Vacancy Rate in the United States
• TOTALSL - Total Consumer Credit Owned and Securitized
• REVOLSL - Revolving Consumer Credit Owned and Securitized
• DRCCLACBS - Delinquency Rate on Credit Card Loans, All Commercial Banks
• GDP - Gross Domestic Product
• GPDI - Gross Private Domestic Investment
• GCE - Government Consumption Expenditures and Gross Investment
• PCEC - Personal Consumption Expenditures
• NETEXP - Net Exports of Goods and Services
• GFDEBTN - Federal Debt: Total Public Debt
• GFDEGDQ188S - Federal Debt: Total Public Debt as Percent of Gross Domestic Product
• FYFSD - Federal Surplus or Deficit
• FGRECPT - Federal Government Current Receipts
• FGEXPND - Federal Government: Current Expenditures
• MANEMP - All Employees, Manufacturing
• USCONS - All Employees, Construction
• USTRADE - All Employees, Retail Trade
• USFIRE - All Employees, Financial Activities
• USGOVT - All Employees, Government
• AWHAETP - Average Weekly Hours of All Employees, Total Private
• DGORDER - Manufacturers' New Orders: Durable Goods
• NEWORDER - Manufacturers' New Orders: Nondefense Capital Goods Excluding Aircraft
• BUSINV - Total Business Inventories
• EXPGS - Exports of Goods and Services
• IMPGS - Imports of Goods and Services
• IR - Import Price Index (End Use): All Commodities
• PPIFIS - Producer Price Index by Commodity: Final Demand

Latest quarter (10-Q)

Latest 10-Q source: 0001193125-26-220572.

Extracted structurally from real Item 2 body heading to real Item 3/4 boundary. Confidence: high. Filing date: 2026-05-13. Report date: 2026-03-31.

ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with the unaudited condensed consolidated financial statements and notes thereto included elsewhere in this Quarterly Report on Form 10-Q, or Form 10-Q, and the audited consolidated financial statements and notes thereto for our fiscal year ended September 30, 2025 included in our Annual Report on Form 10-K for that fiscal year, which is referred to as our 2025 Form 10-K. Please refer to our note regarding forward-looking statements on page 2 of this Form 10-Q, which is incorporated herein by this reference.

The Enanta name and logo are our trademarks. This Form 10-Q also includes trademarks, trade names and service marks of other persons. All other trademarks, trade names and service marks appearing in this Form 10-Q are the property of their respective owners.

Overview

We are a biotechnology company that uses our robust, chemistry-driven approach and drug discovery capabilities to discover and develop small molecule drugs for virology and immunology indications.

Virology:

We discovered glecaprevir, the second of two antiviral protease inhibitors developed through our collaboration with AbbVie for the treatment of acute or 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 has been marketed under the tradenames MAVYRET® (U.S.) and MAVIRET® (ex-U.S.) (glecaprevir/pibrentasvir) since 2017 for the treatment of chronic HCV. MAVYRET® was also approved as the first and only treatment for acute HCV infection in June 2025.

Our active development programs in virology are focused on 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. Populations at high risk for severe RSV infection include infants and young children, adults older than 65 years of age, and those with comorbidities such as chronic heart or lung disease. Recent CDC estimates suggest a significant RSV burden in the U.S., with up to 6.5 million outpatient visits, 350,000 hospitalizations and 23,000 deaths annually.

We also have clinical-stage programs in virology for SARS-CoV-2, the virus that causes COVID-19, and Hepatitis B virus, or HBV, the most prevalent chronic hepatitis.

Immunology:

In immunology, we are designing and developing highly potent and selective, oral small molecule inhibitors for the treatment of type 2 inflammatory disease by targeting key mechanisms of the immune response. An overactive immune response is a primary driver of a number of inflammatory diseases for which there is an enduring unmet need including atopic dermatitis, or AD, urticarias, asthma, prurigo nodularis, or PN, chronic rhinosinusitis with nasal polyps, or CRSwNP, as well as some forms of chronic obstructive pulmonary disease, or COPD, and other conditions. Based on industry reports, by 2030 the market is projected to be approximately $5 billion for urticaria, $30 billion for AD and $35 billion for the combined market of asthma, COPD, CRSwNP, and PN.

Our initial immunology targets involve the following mechanisms of immune response:

•
KIT, a receptor tyrosine kinase, critical for regulating mast cell survival and activation, including release of potent inflammatory mediators such as histamine, which is a primary driver of inflammation and implicated in multiple allergic diseases;

•
STAT6, a transcription factor uniquely responsible for interleukin-4, or IL-4, and interleukin-13, or IL-13, cell signaling, which drives a type 2 dominant phenotype and downstream inflammation; and

•
MRGPRX2, a non-canonical G-Protein-Coupled-Receptor (GPCR) expressed predominantly on mast cells, which upon activation triggers degranulation and release of inflammation mediating components, leading to an inflammatory response that is a driver in multiple allergic diseases.

These mechanisms are implicated, along with others, in several diseases, and it is not uncommon for an efficacious treatment for one disease to be tested and approved for other immunology indications. In addition, these mechanisms are orthogonal approaches that may provide additive or complementary benefit if used in combination. We currently plan to focus our initial immunology drug development, proof-of-concept efforts on the following disease indications:

•
Urticaria, including chronic spontaneous urticaria, or CSU, a severely debilitating, chronic inflammatory skin disease manifested by hives, angioedema, which is swelling of soft tissues, or both, but with no identified triggers, which has an estimated global prevalence of between 0.5% – 1% of the population, resulting in approximately 1.75–3.5 million people

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with this condition at any given time in the U.S. alone or chronic inducible urticaria (CIndU) of various forms with a variety of known triggers; and

•
Atopic dermatitis, or AD, a chronic dermatological disease characterized by dry, red, inflamed, irritated and itchy skin with significant quality of life impacts such as leading a limited lifestyle, avoidance of social interactions and a reduced range of activities, with AD affecting 7.3% of the U.S. adult population, of whom approximately 40% have moderate to severe disease.

As of March 31, 2026, we had $227.0 million in cash, cash equivalents and short-term and long-term marketable securities. Based on our operating plan, we believe that our existing cash, cash equivalents and short-term and long-term marketable securities as of March 31, 2026, as well as the cash flows from our retained portion of future HCV royalties, will enable us to fund our operating expenses and capital expenditure requirements into fiscal 2029.

Our Wholly-Owned Programs

All of our development programs are wholly-owned, including our RSV and immunology programs.

RSV. We have two clinical stage candidates for RSV – zelicapavir (formerly EDP-938) and EDP-323. Both candidates inhibit viral replication and the production of new virions. These clinical candidates differ from fusion inhibitors, which act only at viral entry. Zelicapavir, which has Fast Track designation from the U.S. Food and Drug Administration, or FDA, is a potent inhibitor of the RSV N-protein. EDP-323, which also has a Fast Track designation from the FDA, is an inhibitor of the RSV L-protein.

•
Zelicapavir - N-protein Inhibitor Candidate: Zelicapavir, a once-daily, oral, direct-acting antiviral selectively targeting the N-protein, has demonstrated statistically significant reductions in RSV viral load and symptoms in a Phase 2 human challenge model clinical study. We believe that zelicapavir has the greatest potential to show optimal efficacy in high-risk populations since these patients have reduced RSV immunity or other comorbidities, which manifest in a higher and longer duration of viral replication and greater disease severity, allowing a bigger window to realize the full potential of zelicapavir. Our development program is focused on evaluating zelicapavir in high-risk populations, including high-risk adults and pediatric patients, all of which have significant unmet need:

o
High-Risk Adults Study of Zelicapavir. In September 2025, we announced positive topline results from a Phase 2b randomized, double-blind, placebo-controlled study evaluating zelicapavir in high-risk adults with RSV, including those who are older than 65 years of age and those who have asthma, chronic obstructive pulmonary disease, or congestive heart failure.

o
Pediatric Study of Zelicapavir. In December 2024, we announced positive topline results from the first-in-pediatrics Phase 2 randomized, double-blind, placebo-controlled study evaluating zelicapavir in hospitalized and non-hospitalized children aged 28 days to 36 months with RSV.

In these Phase 2 clinical studies, zelicapavir has demonstrated a favorable safety profile, consistent with that observed in over 700 subjects exposed to zelicapavir to date, as well as antiviral activity and reductions in symptom duration. We are continuing to conduct enabling activities for a pivotal study of zelicapavir in high-risk patients with RSV, including engaging with the FDA on the registrational development path. We plan to provide an update on the study design and development path in the second quarter of 2026. In parallel, we are exploring potential business development opportunities related to our RSV programs.

•
EDP-323 - L-protein Inhibitor Candidate: Our second clinical RSV candidate, EDP-323, is an oral, once-daily, 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 in vitro and protected mice from RSV infection in a dose-dependent manner 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.

o
Phase 2a Study of EDP-323. In September 2024, we announced positive topline results for EDP-323 in a Phase 2a challenge study of healthy adults infected with RSV, which demonstrated statistically significant reductions in RSV viral load and symptoms. In addition, a post-exposure prophylaxis analysis was performed in subjects who were not infected by Day 5 after RSV exposure. The data showed the potential for EDP-323 to be effective in preventing RSV infection when initiated up to five days after RSV exposure.

Immunology. We are leveraging our expertise in developing small molecule inhibitors to design and develop highly potent and selective oral medicines targeting the following mechanisms of immune response:

•
KIT Inhibitors. We have a clinical-stage program to develop oral KIT inhibitors for the treatment of CSU and potentially other mast cell-associated indications by depleting mast cells, thereby addressing a primary driver of these diseases. We

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have selected EDP-978 as our clinical candidate. EDP-978 demonstrates potent nanomolar activity in both binding and cellular function assays, sub-nanomolar activity in vivo, and high selectivity for KIT versus other kinases. EDP-978 also demonstrates strong in vitro and in vivo absorption, distribution, metabolism and excretion, or ADME, properties, supporting once-daily dosing. In April 2026, we dosed our first participant in a randomized, double-blind, placebo-controlled, first-in-human Phase 1 clinical trial. The trial is expected to enroll approximately 98 healthy adult volunteers, ranging in age from 18 to 65 years old, to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics, including serum tryptase, of EDP-978. The trial includes a single ascending dose (SAD) phase, with a two-part food-effect cohort, and a multiple ascending dose (MAD) phase with a 14-day treatment period. We expect to report topline data from this trial in the fourth quarter of 2026.

•
STAT6 Inhibitors. We have a pre-clinical stage program to develop oral inhibitors of the signal transducer and activator of transcription 6 transcription factor, known as STAT6, for the treatment of type 2 immune-driven diseases. STAT6 is responsible for IL-4/IL-13 signaling, the pathway targeted by dupilumab, an IL-4 and IL-13 monoclonal antibody marketed as DUPIXENT®. We are initially focusing on AD for a proof-of-concept clinical study, and subsequently other indications where dupilumab is approved or has shown clinical activity. EPS-3903 is our lead development candidate, which has demonstrated nanomolar potency in both binding and cellul

[Excerpt truncated for page length; source filing is linked above.]

Latest 10-K MD&A

Extracted structurally from real Item 7 body heading to real Item 7A/8 boundary. Confidence: high. Filing date: 2025-11-19. Report date: 2025-09-30.

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

We are a biotechnology company that uses our robust, chemistry-driven approach and drug discovery capabilities to discover and develop small molecule drugs for virology and immunology indications.

Virology

We discovered glecaprevir, the second of two antiviral protease inhibitors developed through our collaboration with AbbVie for the treatment of acute or 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 has been marketed under the tradenames MAVYRET® (U.S.) and MAVIRET® (ex-U.S.) (glecaprevir/pibrentasvir) since 2017 for the treatment of chronic HCV. MAVYRET® was also approved as the first and only treatment for acute HCV infection in June 2025.

Our active development programs in virology are focused on respiratory syncytial virus, or RSV, the most common cause of bronchiolitis and pneumonia and a leading cause of U.S. hospitalization in young children and a significant cause of respiratory illness in older adults. Populations at high risk for severe RSV infection include infants and young children, adults older than 65 years of age, and those with comorbidities such as chronic heart or lung disease. Recent CDC estimates suggest a significant RSV burden in the U.S., with up to 6.5 million outpatient visits, 350,000 hospitalizations and 23,000 deaths annually.

We also have clinical stage programs in virology for SARS-CoV-2, the virus that causes COVID-19, and Hepatitis B virus, or HBV, the most prevalent chronic hepatitis.

Immunology

In immunology, we are designing and developing highly potent and selective oral small molecule inhibitors for the treatment of type 2 inflammatory disease by targeting key mechanisms of the immune response. An overactive response is a primary driver of a number of inflammatory diseases.

Our initial immunology targets involve the following mechanisms of immune response:

•
The receptor tyrosine kinase, known as KIT, which is critical for regulating mast cell survival and activation, including release of potent inflammatory mediators such as histamine, which is a primary driver of inflammation in the skin and implicated in multiple allergic diseases; and

•
STAT6, a transcription factor uniquely responsible for interleukin-4, or (IL-4)/interleukin-13, or (IL-13) cell signaling, which drives a type 2 dominant phenotype and downstream inflammation.

These mechanisms are implicated, along with others, in several diseases, and it is not uncommon for an efficacious treatment for one disease to be tested and approved for other immunology indications. We currently plan to focus our initial immunology drug development proof-of-concept efforts on the following disease indications:

•
Chronic spontaneous urticaria, or CSU, a severely debilitating, chronic inflammatory skin disease manifested by hives, angioedema, which is swelling of soft tissues, or both, but with no identified triggers, which has an estimated global prevalence of between 0.5% – 1% of the population, resulting in approximately 1.75 - 3.5 million people with this condition at any given time in the U.S. alone or chronic inducible urticaria (CIndU) of various forms with a variety of known triggers; and

•
Atopic dermatitis, or AD, a chronic dermatological disease characterized by dry, red, inflamed, irritated and itchy skin with significant quality of life impacts such as leading a limited lifestyle, avoidance of social interactions and a reduced range of activities, with AD affecting 7.3% of the US adult population, of whom ~40% have moderate to severe disease.

As of September 30, 2025, we had $188.9 million in cash, cash equivalents and short-term marketable securities. Based on our operating plan, we believe that our existing cash, cash equivalents and short-term marketable securities as of September

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30, 2025, as well as the cash flows from our retained portion of future HCV royalties and the proceeds from our public offering in October 2025, will enable us to fund our operating expenses and capital expenditure requirements into fiscal 2029.

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.

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. In June 2025 it was also approved by the FDA as the first and only treatment for acute HCV infection. 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. 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 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 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 continue to record 100% of HCV royalties earned under the AbbVie agreement as royalty revenue in our consolidated statements of operations. 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. We completed two Phase 2b studies of zelicapavir and a Phase 2a human challenge study of EDP-323, both of which are in our virology program. We also are conducting preclinical discovery research efforts in immunology.

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 have completed our Phase 2 studies of zelicapavir and EDP-323 and we are evaluating partnering opportunities for the RSV programs.

Through September 30, 2025, we have funded our operations primarily through royalty payments received under our collaboration agreement with AbbVie, a $200.0 million payment received in April 2023 from our royalty sale agreement, and our existing cash, cash equivalents, and short-term marketable securities. Based on our operating plan, we believe that our existing cash, cash equivalents and short-term marketable securities as of September 30, 2025, as well as the cash flows from our retained portion of future HCV royalties and the proceeds from our public offering in October 2025, will enable us to fund our operating expenses and capital expenditure requirements into fiscal 2029.

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 acute or 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.

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The following table is a summary of revenue recognized for the years ended September 30, 2025, 2024, and 2023:

Years Ended September 30,

2025

2024

2023

(in thousands)

Revenue

Royalty revenue

$

65,324

$

67,635

$

78,204

License revenue

—

—

1,000

Total revenue

$

65,324

$

67,635

$

79,204

As disclosed above regarding our OMERS royalty sale agreement, we 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.

At any given time, we have later stage programs in clinical development as well as several active early-stage research and drug discovery projects. Our internal resources, employees and infrastructure are utilized across multiple projects, including our early-stage discovery projects. As such, we report information regarding costs incurred based on our programs (i.e., disease area) rather than on a project specific basis. All indirect costs are allocated to programs based on headcount and square footage of our facilities. 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 have completed our Phase 2 studies of zelicapavir and EDP-323 and we are evaluating partnering opportunities for the RSV programs. 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.

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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 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, patent expenses and litigation expenses associated with prosecuting our patent infringement litigation.

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.

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 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 marketable securities balances. Investment income consists of the amortization or accretion of any purchased premium or discount, respectively, on our 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 Benefit (Expense)

Income tax benefit (expense) is based on our best estimate of taxable net income (loss), applicable income tax rates, net research and development tax credits and carryforwards, net operating loss carrybacks and interest earned on such refunds, changes in valuation allowance estimates and deferred income taxes.

On July 4, 2025, the U.S. government enacted the One Big Beautiful Bill Act ("OBBBA"), which includes several changes to U.S. federal income tax law, including the temporary and permanent extension of expiring provisions of the Tax Cuts and Jobs Act of 2017. We determined that the tax provisions of the legislation do not have a material impact on our 2025 consolidated financial statements and continue to assess the impact on future years.

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.

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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

Years Ended September 30,

2025

2024

2023

(in thousands)

Revenue

$

65,324

$

67,635

$

79,204

Research and development

106,740

131,476

163,524

General and administrative

43,933

57,850

52,887

Interest expense

(7,681

)

(10,940

)

(5,148

)

Interest and investment income, net

9,442

14,770

11,360

Change in fair value of Series 1 nonconvertible

   preferred stock

39

73

—

Income tax benefit (expense)

1,660

1,743

(2,821

)

Net loss

$

(81,889

)

$

(116,045

)

$

(133,816

)

Comparison of the Years Ended September 30, 2025 and 2024

Revenue

We recognized revenue of $65.3 million and $67.6 million during the years ended September 30, 2025 and 2024, respectively. The decrease in revenue year-over-year was primarily due to AbbVie’s lower reported HCV sales as compared to the comparable period in 2024.

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, the number of patients treated and the effect of the label expansion for MAVYRET in the United States for the treatment of patients with acute HCV. 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.

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.

64

Research and development expenses

Years Ended September 30,

2025

2024

2023

(in thousands)

R&D programs:

Virology

RSV

$

59,808

$

86,367

$

78,120

COVID-19

587

4,625

66,082

HBV

152

371

6,974

Total Virology

$

60,547

$

91,363

$

151,176

Immunology

KIT

18,052

19,822

—

STAT6

16,614

4,691

—

Total Immunology

$

34,666

$

24,513

$

—

Other Programs

Early discovery

11,328

14,995

8,253

Other programs for out-licensing

199

605

4,095

Total Other Programs

$

11,527

$

15,600

$

12,348

Total research and development expenses

$

106,740

$

131,476

$

163,524

Research and development expenses for the year ended September 30, 2025 decreased by $24.7 million compared to the same period in 2024.

Virology

The costs in our virology program decreased by $30.8 million primarily due to the timing of clinical trials in our RSV programs.

Immunology

The costs in our immunology programs increased by $10.2 million as we advance this new therapeutic area of focus for the company.

Other Programs

Other program costs decreased by $4.1 million due to the completion of the discovery-stage activities related to our STAT6 program.

General and administrative expenses

General and administrative expenses decreased by $13.9 million for the year ended September 30, 2025, compared to the same period in 2024, primarily due to a decrease in legal expenses related to our patent infringement suit against Pfizer and a decrease in stock-based compensation expenses.

Other income (expense)

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

Interest expense

Interest expense decreased by $3.3 million for the year ended September 30, 2025, as compared to the same period in 2024, due to the paydown of our obligation associated with our royalty sale agreement entered into during April 2023 with an affiliate of OMERS.

Interest and investment income, net

Interest and investment income, net, decreased by $5.3 million for the year ended September 30, 2025, as compared to the same period in 2024. The decrease was due to lower cash and investment balances year over year.

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Income tax benefit (expense)

During each of the years ended September 30, 2025 and 2024, we recorded an income tax benefit of $1.7 million, representing interest recorded on our $33.8 million federal tax refund, which we received in April 2025.

On July 4, 2025, the U.S. government enacted the One Big Beautiful Bill Act ("OBBBA"), which includes several changes to U.S. federal income tax law, including the temporary and permanent extension of expiring provisions of the Tax Cuts and Jobs Act of 2017. We determined that the tax provisions of the legislation do not have a material impact on our 2025 consolidated financial statements and continue to assess the impact on future years.

Comparison of the Years Ended September 30, 2024 and 2023

For a discussion of our results of operations for the year ended September 30, 2024, as compared to the year ended September 30, 2023, 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, 2024 and 2023 included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024.

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, 2025, our principal sources of liquidity were cash and cash equivalents and short-term marketable securities of $188.9 million.

The following table shows a summary of our cash flows:

Years Ended September 30,

2025

2024

2023

(in thousands)

Cash provided by (used in):

Operating activities

$

(19,272

)

$

(78,764

)

$

(103,154

)

Investing activities

40,347

58,235

(53,578

)

Financing activities

(26,618

)

(27,626

)

198,126

Net (decrease) increase in cash, cash equivalents and

   restricted cash

$

(5,543

)

$

(48,155

)

$

41,394

Net cash used in operating activities

Cash used in operating activities was $19.3 million for the year ended September 30, 2025 as compared to cash used in operating activities of $78.8 million for the same period in 2024. The decrease in cash used in operating activities of $59.5 million was primarily driven by lower operating expenses and receipt of a $33.8 million income tax refund in April 2025, partially offset by lower cash receipts associated with our AbbVie agreement.

Net cash provided by (used in) investing activities

Cash provided by investing activities was $40.3 million for the year ended September 30, 2025 as compared to cash provided by investing activities of $58.2 million for the same period in 2024. Our cash provided by investing activities decreased $17.9 million, driven by timing of purchases, sales and maturities of marketable securities in 2025 compared to 2024. This decrease was partially offset by a reduction in capital expenditures in fiscal 2025 as we completed the buildout of our new office and laboratory space at 4 Kingsbury Avenue in 2025.

Net cash (used in) provided by financing activities

Cash used in financing activities was $26.6 million for the year ended September 30, 2025 as compared to cash used in financing activities of $27.6 million for the same period in 2024. Our cash used in financing activities decreased $1.0 million, driven primarily by lower payments on our royalty sale agreement with OMERS.

Year Ended September 30, 2024

For a discussion of our cash flows for the year ended September 30, 2024, 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, 2024.

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Funding Requirements

As of September 30, 2025, we had $188.9 million in cash, cash equivalents and short-term marketable securities. Based on our operating plan, we believe that our existing cash, cash equivalents and short-term marketable securities as of September 30, 2025, as well as the cash flows from our retained portion of future HCV royalties and the proceeds from our public offering in October 2025, will enable us to fund our operating expenses and capital expenditure requirements into fiscal 2029. 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 litigation 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

Facility Leases

As of the date of this report, we lease space in Watertown, Massachusetts, under two separate lease agreements with one landlord.

In May 2022, we entered into a ten-year lease for new laboratory and office space in Watertown, Massachusetts, adjacent to our 400 Talcott Avenue premises at Arsenal on the Charles at 4 Kingsbury Avenue since our lease for office and laboratory space at 500 Arsenal Street was to expire on September 1, 2027. The construction of the facility shell was completed and we gained access to the building to construct tenant improvements during the three months ended March 31, 2024. Upon gaining access to the 4 Kingsbury Avenue building, we capitalized a right-of-use asset and lease liability of approximately $32 million on our consolidated balance sheets which reflects our fixed base rent payments, net of approximately $15 million of a

67

tenant improvement allowance provided by the landlord, over the 10-year term of the lease. The 4 Kingsbury Avenue lease ends September 30, 2034.

In conjunction with the commencement of our lease at 4 Kingsbury Avenue during the three months ended March 31, 2024, we adjusted our 500 Arsenal Street lease liability to shorten the expiration date from September 2027 to the date the 4 Kingsbury Avenue building became ready for our occupancy. This resulted in a decrease in the lease liability and right-of-use asset on our consolidated balance sheets by approximately $9.0 million. The rent commencement date for our 4 Kingsbury Avenue lease was September 12, 2024, and we moved into the space in November 2024 at which time our lease at 500 Arsenal Street expired.

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. In July 2024, we amended our lease agreement to confirm alignment with the lease end date of our 4 Kingsbury Avenue lease at September 30, 2034.

Total estimated minimum lease payments for the next 5 years and thereafter under our existing facility and leased equipment agreements are $8.5 million in 2026, $8.7 million in 2027, $9.0 million in 2028, $9.3 million in 2029, $9.5 million in 2030, and $41.1 million thereafter.

Preferred Stock

As of September 30, 2025, 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 $1.3 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, 2025. 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.

OMERS Agreement

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.