Atea Pharmaceuticals (NASDAQ:AVIR) outlined progress in its hepatitis C (HCV) late-stage development program and provided an update on its newly expanded hepatitis E virus (HEV) pipeline during its fourth quarter and full-year 2025 financial results conference call. Management also discussed commercial launch preparations for HCV and reviewed the company’s year-end cash position and spending outlook.
Phase 3 HCV program on track for 2026 readouts
Founder and CEO Dr. Jean-Pierre Sommadossi said the company made “substantial clinical progress” over the past year advancing its global Phase 3 program evaluating bemnifosbuvir plus ruzasvir for HCV. Atea expects top-line readouts in 2026 from both pivotal trials, C-BEYOND and C-FORWARD, which are comparing the company’s regimen against sofosbuvir/velpatasvir (Epclusa).
In patients without cirrhosis, treatment is eight weeks with bemnifosbuvir/ruzasvir versus 12 weeks with standard of care; patients with compensated cirrhosis receive 12 weeks on either regimen. The primary endpoint in both studies is sustained virologic response (SVR) 24 weeks after treatment initiation.
- C-BEYOND: Enrollment completed in December; top-line results expected mid-year 2026.
- C-FORWARD: Enrollment expected to complete by mid-year 2026; top-line results expected by year-end 2026.
Horga also detailed differences in primary analysis populations: C-BEYOND will analyze the primary endpoint in a modified intent-to-treat (mITT) population as preferred by the U.S. FDA, while C-FORWARD will use a per-protocol primary analysis as preferred by the EMA, with each study including the other population as a key secondary endpoint. The trials are powered at 90% with a 5% non-inferiority margin, with expected rates approximating 95% in an mITT population, she said.
During Q&A, Horga said enrollment of cirrhotic patients “has not been an issue” and stated the company expects to achieve enrollment targets across both trials.
Management highlights Phase 2 profile and differentiation goals
Chief Development Officer Dr. Janet Hammond framed the HCV opportunity around increasing infection rates and persistent gaps between diagnosis and treatment. Hammond said that, in the U.S., out of 160,000 reported new chronic infections, about 85,000 patients are treated annually. She added that the estimated number of infected people in the U.S. has increased from about 2.5 million in 2015 to roughly 4 million today, and that most countries are not on track to meet the World Health Organization’s HCV elimination goals.
Hammond also cited Phase 2 results presented at the EASL Congress 2025 and AASLD’s The Liver Meeting 2025. In a Phase 2 study in 275 patients, the eight-week bemnifosbuvir/ruzasvir regimen achieved 98% SVR12 in a protocol treatment-adherent population and 95% SVR12 in the efficacy-evaluable population, she said. Hammond added that the regimen demonstrated a high barrier to resistance and a low risk for drug-drug interactions, including with proton pump inhibitors (PPIs), H2 blockers, and standard HIV therapy. She also said there is no need for dose adjustment of bemnifosbuvir in patients with hepatic or renal impairment, and the regimen can be taken with or without food.
Hammond noted “recently generated data” suggesting bemnifosbuvir inhibits HCV not only by chain termination of RNA replication but also by inhibiting assembly and secretion of new virions, which she said helps explain its antiviral potency.
Commercial strategy centered on “test and treat” and focused salesforce
Chief Commercial Officer John Vavricka said Atea has heard consistently from healthcare providers about the potential benefits of a “test and treat” model of care that enables testing, diagnosis, and treatment at the point of care. He said the model has support from the CDC and is gaining momentum through bipartisan efforts tied to HCV elimination.
Vavricka described U.S. HCV prescribing as concentrated, with about 6,000 prescribers writing 80% of direct-acting antiviral prescriptions, which he said supports an efficient commercial approach. The company anticipates a U.S. commercial salesforce of around 75 people, including sales and medical science liaisons, and plans a blister-card packaging format with a “simple 4-week dosing package” intended to support convenience and adherence.
On pricing and contracting, Vavricka said the specialty distribution market is organized into commercial, Medicare, and Medicaid segments, describing the pathways as “known” and “fully utilized.” He said Atea’s preliminary payer research indicated interest in the regimen’s profile and willingness to include it on formularies. Vavricka also said pricing has been “relatively stable,” adding that list pricing has increased slightly year over year while net pricing declined, and that net pricing has been relatively stable over the past two to three years. He also said market shares are nearing “a 50/50 with the favoring Epclusa.”
Vavricka also referenced an IQVIA quantitative market research study with 153 high-prescribing U.S. physicians using Phase 2 results. He said physicians indicated they would likely prescribe bemnifosbuvir/ruzasvir to about half of their patients, and that results were similar regardless of cirrhosis status.
HEV expansion: AT-587 selected as lead candidate
Sommadossi said Atea expanded its antiviral hepatitis pipeline to target chronic HEV infections in immunocompromised patients, describing the condition as having no approved therapy and the potential to progress rapidly to cirrhosis within three to five years if untreated. He discussed data presented at CROI 2026 and at the JPMorgan Healthcare Conference supporting AT-587 as a potential first-in-class inhibitor against HEV.
Management described HEV epidemiology, noting that in developed countries genotype 3 is predominantly transmitted through contaminated food (such as undercooked meat) and can cause chronic hepatitis in immunocompromised patients. Sommadossi said the current standard of care includes reducing immunosuppression and/or ribavirin, which he said presents challenges.
Atea estimated that about 3%—or approximately 450,000—at-risk patients in the U.S. and Europe with underlying immunocompromising conditions could develop chronic HEV each year, and management estimated a market opportunity of $750 million to $1 billion annually, noting this would “follow on orphan designation.”
Sommadossi said Atea selected AT-587 as the lead candidate based on more potent in vitro activity versus bemnifosbuvir and positive pharmacokinetic (PK) data. He cited nanomolar antiviral activity against HEV genotype 3 and activity against clinical ribavirin resistance-associated substitutions. He also said single-dose PK studies in rats and monkeys showed high plasma concentrations of an active triphosphate metabolite surrogate comparable to bemnifosbuvir, and that AT-587 efficiently converted to its active triphosphate in human hepatocytes. Management said AT-587 has shown a “clean preclinical safety profile” to date.
The company has initiated IND/CTA-enabling studies and anticipates starting a first-in-human study mid-year 2026, with management citing a goal of proof of concept by year-end and the possibility of advancing to a Phase 2/3 trial in the second half of 2027.
Cash position, spending focus, and Merck license obligations
Chief Financial Officer Andrea Corcoran said Atea ended 2025 with $301.8 million in cash, cash equivalents, and marketable securities. She said 2025 spending was principally directed to advancing the Phase 3 HCV program and discovery efforts that led to the January 2026 nomination of AT-587 as the lead HEV candidate. Corcoran also noted the company returned $25 million to stockholders through a share repurchase program in 2025.
Corcoran said R&D expenses increased in 2025 versus 2024, driven primarily by higher external spending for the HCV Phase 3 program, partially offset by lower COVID-19 clinical development spending and lower internal expenses, including reduced stock-based compensation and lower payroll-related costs. G&A expenses decreased, primarily due to lower stock-based compensation, partially offset by increased professional fees.
Looking to 2026, Corcoran said Atea intends to maintain financial discipline, with the “substantial majority” of spending focused on advancing the HCV program as it completes Phase 3 trials, prepares regulatory submissions, and conducts pre-launch activities including manufacturing commercial launch supply. Management reiterated its expectation that the company’s cash runway extends through 2027.
In response to a question about a Merck license agreement, Corcoran said Atea in-licensed ruzasvir and will pay milestones and royalties to Merck upon successful commercialization. She said the next milestone is due upon NDA submission and approval, which the company believes is in 2027.
About Atea Pharmaceuticals (NASDAQ:AVIR)
Atea Pharmaceuticals, Inc is a clinical-stage biopharmaceutical company focused on the discovery and development of oral antiviral therapeutics targeting RNA viruses. The company’s lead program, AT-527, is a direct-acting nucleotide prodrug licensed from Roche and is being evaluated as a potential treatment for coronavirus disease 2019 (COVID-19). In addition to its COVID-19 efforts, Atea’s pipeline includes other small-molecule candidates for hepatitis C virus and emerging RNA pathogens, leveraging its proprietary nucleotide chemistry platform to address significant unmet medical needs in infectious diseases.
Founded in 2014 and headquartered in Cambridge, Massachusetts, Atea operates research laboratories in the Greater Boston area and conducts clinical studies across North America, Europe and parts of Asia.
