ENTA 10-K & 10-Q changes, risk factors and insider trading

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

Accordingly, we will need to obtain additional funding to support our operations. In October 2025, we completed a public offering of our common stock, resulting in gross proceeds of approximately $74.8 million. 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.

In recent years, federal and state governments have proposed or implemented Most Favored Nation, or MFN, pricing models that tie reimbursement rates for certain drugs to the lowest prices paid by other countries. 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.

There are several prophylaxis options on the market or in development. AstraZeneca/Sanofi (BEYFORTUS®) and Merck (Clesrovimab – Phase 3 completeENFLONSIA™) arehave developingapproved long-acting monoclonal antibodies for prophylaxis use in infants, and Pfizer has an approved maternal vaccine (ABRYSVO®), all of which provide passive immunity to infants. Sanofi is also evaluating a vaccine in infants and toddlers (RSVt vaccine – Phase 3). There are also two approved RSV vaccines for high-risk adults overage 18 – 59 years and for all adults age 60 years ofand ageabove (Pfizer/ABRYSVO® and Moderna/MresviamRESVIA®) and one approved RSV vaccine for high-risk adults overage 5050-59 years ofand in adults age 60 years and older (GSK/AREXVY®).

For CSU, there are a number of different mechanisms being explored, including inhibitors of IL-4R, IgE, BTK, SIGLEC-6, and MRGPRX2. Specifically for KIT inhibitors, there are companies with antibodies in development, including Celldex (barzolvolimab - Phase 3) and Jasper (briquilimab - Phase 1b/2a), as well as companies with oral, small molecules in early clinical or preclinical development, including Third Harmonic, Blueprint, Arcus, and Alivexis.Sanofi/Blueprint.

For AD, the moderate-severe atopic dermatitis treatment landscape is dominated by biologics targeting the IL-4 and/or IL-13 pathway (e.g., DUPIXENT® (dupilumab) and, ADBRY® (tralokinumab-ldrm), and EBGLYSS™ (lebrikizumab-lbkz)), with JAK inhibitors (e.g., RINVOQ® (upadacitinib) and CIBINQO® (abrocitinib)) as the only oral option. Multiple oral mechanisms are in development, including inhibitors of MRGPRX2, IRAK4, ITK, STAT6, RASP and PKM2. The latest stage oral assets being evaluated in moderate-severe AD patients are in Ph2Phase 2b (IncyteEvommune MRGPRX2) –and Ph2aPhase 1 (Corvus ITKl; Sanofi/Kymera IRAK4 – Ph2STAT6)). For STAT6 inhibitors specifically, companies with oral assets in preclinical development include KymeraSanofi/Recludix, (KT-621J&J/Katen, –Gilead/LEO, Phase 1)DeepCure and Sanofi/RecludixJW (preclinical).Pharma.

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.

For COVID, there are two oral antiviral treatments for non-hospitalized, high-risk patients with SARS-CoV-2 infection: PAXLOVID™, a 3CL protease inhibitor (nirmatrelvir) boosted with ritonavir (full approval), and LAGEVRIO™ (molnupiravir), a polymerase inhibitor (Emergency Use Authorization). ThereThe aremost no oraladvanced direct acting antiviralsoral antiviral for the treatment of high-risk patients with SARS-CoV-2 is in latePhase stage3 global clinical trials.(ibuzatrelvir).

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 RSVclinical-stage programs, we will need to successfully:

If we are not successful in developing zelicapavir or EDP-323, or discovering and developing KIT and STAT6 inhibitors, or in obtaining aone partneror more partners to advance zelicapavir, EDP-323, EDP-235 or EDP-514, or in discovering further product candidates, our ability to expand our business and achieve our strategic objectives will be impaired.

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, Tara Kieffer, our Chief Product Strategy Officer, and Scott T. Rottinghaus, M.D., our Senior Vice President and Chief Medical Officer, as well as other employees and consultants. Although none of Drs. Luly, Or, Kieffer 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.

To date we have only tested our product candidates through initial Phase 2 clinical 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.

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 latestmost recent 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 selected in August 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.

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. For example, in recent years, federal and state governments have proposed or implemented MFN pricing models that tie reimbursement rates for certain drugs to the lowest prices paid by other countries. 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.

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, our continued development of EDP-235 and EDP-514 are dependent on establishing collaborations. We are also evaluating potential partnership opportunities to advance our RSV programs to the next stage of clinical development. 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.

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 partythird-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, pandemic or other cause, 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. In addition, our contract manufacturers and researchers in China may be subject to U.S. legislation, sanctions, tariffs, trade restrictions and other foreign regulatory requirements, which could increase the cost or reduce the supply of material available to us or delay or prevent the procurement or supply of such material. Any of these matters could materially and adversely affect our business and results of operations despite our ongoing efforts to mitigate these risks. For example, the recently proposed BIOSECURE ActAct, thatcurrently wasunder passedconsideration by the U.S. House of Representatives in September 2024, as well as a substantially similar bill in the U.S. Senate,Congress, target U.S. government contracts, grants, and loans for entities that use equipment and services from certain named Chinese biotech companies, and authorize the U.S. government to name additional Chinese biotechnology companies of concern. If these bills become law, or similar laws are passed, they would have the potential to severely restrict the ability of companies to work with certain Chinese biotechnology companies of concern without losing the ability to contract with, or otherwise receive funding from, the U.S. government.

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, as has been asserted by Pfizer in our patent infringement suit in the United States regarding Paxlovid, Pfizer’s antiviral treatment for COVID-19. In patent litigation in the United StatesStates, Europe 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, which does not cover EDP-235, 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, as has been and may continue to be the case with the Pfizer suit,litigation, and may divert the efforts of our scientific and management personnel.

We are increasingly dependent upon information technology systems, infrastructure, and data to operate our business. We also rely on third partythird-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.

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

We discovered glecaprevir, the second of two antiviral protease inhibitors discovered and 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 2017.2017 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,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 suggestingsuggest thata on average each yearsignificant RSV leads to three million hospitalizations globally in children under 5 years old and 177,000 hospitalizationsburden in the U.S.U.S., inwith adultsup overto the6.5 agemillion ofoutpatient 65.visits, 350,000 hospitalizations and 23,000 deaths annually.

In immunology, we are designing and developing highly potent and selective,selective oral small molecule inhibitors for the treatment of type 2 inflammatory disease by targeting key mechanisms of the immune response. Our initial focus has been on mechanisms involved in an overactive type 2 immune response, which is the reaction of the body's immune system when the body detects infections or allergens and sends out immune cells to fight them. An overactive response is a primary driver of a number of inflammatory diseases.

The receptor tyrosine kinase, known as KIT, which is critical for regulating mast cell activitysurvival 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-4interleukin-4, or (IL-4)/interleukin-13interleukin-13, or (IL-13) cell signaling, thewhich factorsdrives thata playtype important2 rolesdominant in regulating the responses of lymphocytes, myeloid cells,phenotype and non-hematopoieticdownstream cells within the immune system.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 1.75-3.51.75 - 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, 2024,2025, we had $248.2$188.9 million in cash, cash equivalents and short-term marketable securities. WeBased on our operating plan, we believe that our existing cash, cash equivalents and short-term marketable securities as of September 30, 2024,2025, 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 2027.2029.

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 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.

We are currently funding all research and development for our wholly-owned programs, which are targeted toward the discovery and development of novel compounds. AsWe of the date of this report, we are conductingcompleted two Phase 2b studies of zelicapavir and have recently completed 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 .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 willhave notcompleted conductour anyPhase further2 developmentstudies of EDP-235zelicapavir intoand Phase 3 studiesEDP-323 and we madeare importantevaluating adjustmentspartnering toopportunities reducefor ourthe spendingRSV significantly in 2024.programs.

ToThrough date,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. WeBased on our operating plan, we believe that our existing cash, cash equivalents and short-term marketable securities as of September 30, 2024,2025, as well as the cash flows from our retained portion of future HCV royalties,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 2027.2029.

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.

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 willhave notcompleted conductour anyPhase further2 developmentstudies of EDP-235zelicapavir intoand Phase 3 studiesEDP-323 and we madeare importantevaluating adjustmentspartnering toopportunities reducefor ourthe spendingRSV significantly in 2024.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.

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 suit.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, but we anticipate inflation may impact future periods.expenses.

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 andregimen, the number of patients treated.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.

The costs in our immunologyvirology programsprogram increaseddecreased by $24.5$30.8 million asprimarily thisdue isto athe new therapeutic areatiming of focusclinical fortrials thein company.our RSV programs.

Other program costs increaseddecreased by $3.3$4.1 million asdue weto focusedthe oncompletion early-stageof drugthe discoverydiscovery-stage programs,activities offsetrelated by a decrease in costs forto our NASH program as we continued to wind down thisSTAT6 program.

General and administrative expenses increaseddecreased by $5.0$13.9 million for the year ended September 30, 2024,2025, compared to the same period in 2023,2024, primarily due to ana increasedecrease in legal expenses related to our patent infringement suit against Pfizer.Pfizer and a decrease in stock-based compensation expenses.

Interest expense increaseddecreased by $5.8$3.3 million for the year ended September 30, 2024,2025, as compared to the same period in 2023,2024, due to the timingpaydown of theour obligation associated with our royalty sale agreement entered into during April 2023 with an affiliate of OMERS.

Interest and investment income, net, increaseddecreased by $3.4$5.3 million for the year ended September 30, 2024,2025, as compared to the same period in 2023.2024. The increasedecrease was due to an increase in average investedlower cash dueand toinvestment receipt of $200.0 million from OMERS in April 2023 as well as changes in interest ratesbalances year over year.

Cash used in operating activities was $78.8$19.3 million for the year ended September 30, 20242025 as compared to cash used in operating activities of $103.2$78.8 million for the same period in 2023.2024. The decrease in cash used in operating activities of $59.5 million was primarily driven by lower researchoperating expenses and developmentreceipt payments,of a $33.8 million income tax refund in April 2025, partially offset by lower cash receipts associated with our AbbVie agreement as we now only retain 45.5% of cash royalties following the royalty sale agreement with OMERS.agreement.

Cash provided by investing activities was $58.2$40.3 million for the year ended September 30, 20242025 as compared to cash usedprovided inby investing activities of $53.6$58.2 million for the same period in 2023.2024. Our cash provided by investing activities increaseddecreased $111.8$17.9 million, driven by timing of purchases, sales and maturities of marketable securities in 20242025 compared to 2023.2024. This increasedecrease was partially offset by increaseda reduction in capital expenditures in fiscal 20242025 foras we completed the buildout of our new office and laboratory space at 4 Kingsbury Avenue.Avenue in 2025.

There have been no material changes to such risk factors during the three months ended MarchJune 31,30, 2026. 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.

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® wasand MAVIRET were also approved as the first and only treatmenttreatments for acute HCV infection in the United States and the European Union in June 2025.2025 and June 2026, respectively.

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 childrenchildren, 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 suggestfrom athe significantUnited States 2024-2025 RSV burdenseason inindicate thethat U.S.,RSV withled to up to 6.56.8 million outpatient visits, 350,000approximately hospitalizations370,000 hospitalizations, and 23,000up deathsto annually.24,000 deaths. We estimate a global market opportunity of over $2 billion for an oral RSV antiviral for children and all high-risk adults, with a potential total addressable population of greater than 3 million patients in the United States. Additionally, we believe that the recent FDA approval of at-home combination self-tests capable of detecting RSV, influenza A & B, and COVID-19 will further drive RSV diagnosis and potentially enable a test-to-treat model for zelicapavir.

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,urticaria, asthma, prurigo nodularis, or PN, chronic rhinosinusitis with nasal polyps, or CRSwNP, as well as some forms of chronic obstructive pulmonary disease, or COPD, eosinophilic esophagitis, or EoE, allergic rhinoconjunctivitis, or ARC, and other conditions. Based on industry reports, by 20302032 the market is projected to be approximately $5$40 billion for urticaria, $30 billion for ADurticaria and $35AD, approximately $40 billion for the combined market of asthma, COPD, CRSwNP, EoE, ARC and PN.PN and could include an additional $40 billion or greater taking into account potential expansion into gastrointestinal and neurology indications thought to be associated with mast cells.

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

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-ReceptorG-Protein-Coupled-Receptor, (GPCR)or 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.diseases, and potentially implicated in migraine.

As of MarchJune 31,30, 2026, we had $227.0$211.5 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 MarchJune 31,30, 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.

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

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.

STAT6 Inhibitors. We have a pre-clinicalpreclinical 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 cellular assays and is highly selective for STAT6 versus other STATs. EPS-3903 results in a rapid, continuous and complete (>90%) inhibition of phosphorylated STAT6 after oral dosing in mice. Importantly, EPS-3903 shows in vivo efficacy comparable to dupilumab, or an anti-mouse IL-4/IL-13 antibody, in multiple disease models of asthma (ovalbumin, house dust mite) and AD (MC903). EPS-3903 displays favorable in vitro and in vivo ADME properties, supportive of once-daily dosing potential. We are currently performing scale-up and Investigational New Drug application, or IND, enabling activities and are on track to file an IND in the second half of 2026.

MRGPRX2 Inhibitors. In January 2026, we announced a pre-clinicalpreclinical program targeting MRGPRX2, a non-canonical G protein-coupled receptor, or GPCR, expressed predominantly on mast cells, for the treatment of type 2 immune driven diseases. MRGPRX2 inhibitors act through non-depleting mast cell modulation, including IgE-independent pathways, and may have the potential to address multiple chronic inflammatory diseases, including urticaria,atopic asthma,dermatitis, prurigo nodularisasthma and others, with strong efficacy and a best-in-disease safety profile.profile as well as potential in migraine. Currently, our prototype inhibitors demonstrate MRGPRX2 inhibition with nanomolar potency (EC50 of 1-2nM) in cellular assays and prevent skin mast cell activation in humanized MRGPRX2 mouse models. Further, our prototype inhibitors show potent activity across multiple MRGPRX2 agonists, with high selectivity for MRGPRX2 versus other GPCRs. These prototypes also demonstrate favorable in vitro and in vivo ADME properties, supportive of once-daily dosing potential. We are continuing to evaluate multiple compounds in pre-clinicalpreclinical studies and expect to select a development candidate in the second half of 2026.

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. InThis June 2025 itproduct was also approved by the FDA and European Commission as the first and only treatment for acute HCV infection.infection in June 2025 and June 2026, respectively. 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.

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 are currentlyadvancing zelicapavir into the RESOLVE study, a registrational Phase 2b/3 clinical trial in adults at high risk of severe outcomes from RSV infection. In addition, we are conducting enablingthe activitiesLOTUS forstudy, a pivotalPhase study2b clinical trial of zelicapavir in high-riskpediatric patients with RSV.RSV, In addition, we initiatedand a Phase 1 clinical trial of EDP-978, our lead immunology program. We are also continuing to conduct pre-clinicalpreclinical discovery research efforts in immunology.

As a result of the timing of our clinical and pre-clinicalpreclinical development programs, we expect our research and development expenses will fluctuate from period to period. In the next 12 months, we expect aan reductionincrease in our external research and development expenses, primarily driven by the timing of clinical trials in our RSV programs.

The following table is a summary of revenue recognized for the three and sixnine months ended MarchJune 31,30, 2026 and 2025:

As our internal product candidates are currently in pre-clinicalpreclinical or 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.

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 pre-clinicalpreclinical 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, pre-clinicalpreclinical study, and clinical trial activities;

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 aan reductionincrease in our external research and development expenses, primarily driven by the timing of clinical trials in our 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 pre-clinicalpreclinical and clinical success and prospects of each product candidate, as well as ongoing assessments of the commercial potential of each product candidate.

Comparison of the Three Months Ended MarchJune 31,30, 2026 and 2025

We recognized revenue of $17.2$14.4 million during the three months ended MarchJune 31,30, 2026 as compared to $14.9$18.3 million during the three months ended MarchJune 31,30, 2025. The $2.2$4.0 million increasedecrease in revenue was primarily due to AbbVie’s higherlower reported HCV sales as compared to the same period in 2025.

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/MAVIRET for the treatment of patients with acute HCV.HCV infection. 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 for the three months ended MarchJune 31,30, 2026 decreased by $8.6$5.1 million compared to the same period in 2025.

General and administrative expenses decreased by $1.8$0.5 million for the three months ended MarchJune 31,30, 2026 compared to the same period in 2025. The decrease was primarily due to lower stock-based compensation expenses during the three months ended MarchJune 31,30, 2026.

Interest expense increased by $1.6$2.5 million for the three months ended MarchJune 31,30, 2026, as compared to the same period in 2025, due to an increase in forecasted royalties arising from AbbVie’s product sales under the AbbVie Agreement and corresponding royalty payment to OMERS arising from such sales pursuant to our OMERS royalty sales agreement.

Interest and investment income, net, decreased by $0.2$0.4 million for the three months ended MarchJune 31,30, 2026, as compared to the same period in 2025. The decrease was due to lower interest rates year over year.

On July 4, 2025, the U.S. government enacted the One Big Beautiful Bill Act, 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, such as 100% bonus depreciation and immediate expensing of domestic research and development costs. The new legislation has multiple effective dates, with certain provisions effective in 2025 and others in the future. We determined that the legislation does not have a material impact on our condensed consolidated financial statements for the three and sixnine months ended MarchJune 31,30, 2026.

Comparison of the SixNine Months Ended MarchJune 31,30, 2026 and 2025

We recognized revenue of $35.8$50.1 million during the sixnine months ended MarchJune 31,30, 2026 as compared to $31.9$50.2 million during the sixnine months ended MarchJune 31,30, 2025. The $3.9$0.1 million increasedecrease in revenue was primarily due to a slight decrease in AbbVie’s higher reported HCV sales as compared to the same period in 2025.

Research and development expenses for the sixnine months ended MarchJune 31,30, 2026 decreased by $15.4$20.5 million compared to the same period in 2025.

General and administrative expenses decreased by $5.7$6.2 million for the sixnine months ended MarchJune 31,30, 2026 compared to the same period in 2025. The decrease was primarily due to lower stock-based compensation expenses during the sixnine months ended MarchJune 31,30, 2026 and a decrease in legal expenses related to our patent infringement suit against Pfizer for the ’953 Patent.

Interest expense increased by $2.7$5.2 million for the sixnine months ended MarchJune 31,30, 2026, as compared to the same period in 2025 due to an increase in forecasted royalties arising from AbbVie’s product sales under the AbbVie Agreement and corresponding royalty payment to OMERS arising from such sales pursuant to our OMERS royalty sales agreement.

Interest and investment income, net, decreased by $0.6$1.0 million for the sixnine months ended MarchJune 31,30, 2026, as compared to the same period in 2025. The decrease was due to lower interest rates year over year.

The income tax expense of less than $0.1 million during the sixnine months ended MarchJune 31,30, 2026 was primarily due to state income taxes. The income tax benefit of $1.7 million during the sixnine months ended MarchJune 31,30, 2025 was primarily due to an additional federal income tax refund from a net operating loss carryback of $0.9 million. We received the federal income tax refund of $33.8 million, inclusive of interest, in April 2025.

We fund our operations with cash flows from our retained portion of our royalty revenue and our existing financial resources. At MarchJune 31,30, 2026, our principal sources of liquidity were cash and cash equivalents and short-term and long-term marketable securities of $227.0$211.5 million.

Cash used in operating activities was $18.9$28.8 million for the sixnine months ended MarchJune 31,30, 2026 as compared to cash used in operating activities of $30.3$12.8 million for the same period in 2025. Our cash used in operating activities decreasedwas bylower $11.4in million2025 primarily due to receipt of a $33.8 million income tax refund in April 2025, partially offset by lower research and development payments.payments in 2026.

Cash used in investing activities was $35.4$21.4 million for the sixnine months ended MarchJune 31,30, 2026 as compared to cash provided by investing activities of $64.5$38.1 million for the same period in 2025. Our cash used in investing activities increased by $99.9$59.4 million, driven by the timing of purchases and maturities of marketable securities in 2026 compared to 2025.

Cash provided by financing activities was $56.8$51.3 million for the sixnine months ended MarchJune 31,30, 2026 as compared to cash used in financing activities of $11.9$18.3 million for the same period in 2025. Our cash provided by financing activities increased by $68.7$69.6 million, driven primarily by proceeds received from our public offering which closed in October 2025.

As of MarchJune 31,30, 2026, we had $227.0$211.5 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 MarchJune 31,30, 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. 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.

As of MarchJune 31,30, 2026, 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 MarchJune 31,30, 2026. 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.

Our condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America. The preparation of our condensed consolidated financial statements and related disclosures requires us to make estimates and assumptions that affect the reported amount of assets, liabilities, revenue, costs and expenses, and related disclosures. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions and conditions. See our 2025 Form 10-K for information about our critical accounting policies as well as a description of our other significant accounting policies. There have been no significantmaterial changes to our critical accounting policies since the beginning of this fiscal year.