Atea Pharmaceuticals Highlights Phase 3 HCV Timeline, Unveils New Hepatitis E Candidate AT-587 at JPMorgan Conference

Atea Pharmaceuticals (NASDAQ:AVIR) used its presentation at the 44th Annual JPMorgan Healthcare Conference to provide updates on its global Phase 3 program for hepatitis C (HCV) and to outline early progress in a new hepatitis E (HEV) antiviral program. CEO and founder J.P. Sommadossi was joined in the Q&A by Chief Development Officer Janet Hammond and Chief Commercial Officer John Vavricka.

Phase 3 hepatitis C program: enrollment progress and timelines

Sommadossi said the company’s global Phase 3 program evaluating bemnifosbuvir combined with ruzasvir has executed “flawlessly” and described 2026 as a pivotal year. He noted bemnifosbuvir was discovered about seven years ago and said the company is now “within six months” of data from the first Phase 3 trial.

The first Phase 3 study, CB-ARC, is a North American trial. Atea announced enrollment completion in December, with “more than 900” patients enrolled. Sommadossi said the company expects results in mid-2026, later characterizing the timing as Q3.

The second Phase 3 study, C-FORWARD, is being conducted outside North America across 17 countries and 120 clinical sites. Sommadossi said enrollment is on track and “probably also ahead of schedule,” with full enrollment expected by the end of next quarter and results anticipated by the end of the year. In his prepared remarks he said the company anticipates filing an NDA with the FDA in the first quarter of 2026, but in closing comments he referenced an NDA filing in Q1 2027.

Sommadossi also highlighted the pace of CB-ARC recruitment, stating the company screened more than 1,300 patients in less than eight months and enrolled 900 patients over the same period, which he said reflects continued need for new regimens in the U.S.

Regimen profile and trial design details

Atea described its HCV regimen as combining bemnifosbuvir, which Sommadossi called “the most potent nucleotide inhibitor,” and ruzasvir, an NS5A inhibitor licensed with global rights from Merck several years ago. Sommadossi said bemnifosbuvir is “about 10 to 50 times more potent than sofosbuvir,” which is part of the sofosbuvir/velpatasvir combination regimen Epclusa.

The company emphasized differentiation around pan-genotypic activity, shorter treatment duration, and low potential for drug-drug interactions, framing these attributes as important for an emerging “test-and-treat” model of care. Both executives cited proton pump inhibitor use as a practical issue in HCV prescribing; Hammond said Epclusa absorption can be reduced when taken with proton pump inhibitors, and noted an estimated 35% of HCV patients use them.

Atea’s Phase 3 program includes two pivotal head-to-head trials against sofosbuvir/velpatasvir. The company said the regimen is being tested as:

• Eight weeks vs. 12 weeks (Epclusa) in non-cirrhotic patients
• 12 weeks vs. 12 weeks in cirrhotic patients

Sommadossi said the studies are not blinded for physicians and patients, but the sponsor does not have access to treatment assignment. He said sustained virologic response (SVR) is assessed 24 weeks after treatment initiation, and discussed how Atea plans to report results using two analysis approaches reflecting differing regulatory preferences in the U.S. and Europe: a per-protocol primary endpoint aligned with EMA expectations and a modified intent-to-treat approach reflecting FDA preferences.

The company also referenced Phase 2 results showing a 98% SVR rate in the per-protocol population. During Q&A, Hammond added that in the Phase 2 study, 17% of patients did not fully adhere to therapy, and said Atea believes high potency could reduce the impact of imperfect adherence, particularly in the second month of treatment.

Market backdrop and commercialization plans

Management pushed back on a perception that HCV is declining in the U.S. Hammond attributed recent trends to the opioid crisis and said the U.S. now has a large and increasing population of younger patients. She cited estimates that about 90,000 patients per year are treated in the U.S., while about 160,000 are newly infected each year, adding that reinfection can occur and that injection drug use can amplify spread.

Vavricka said the global HCV market is around $3 billion in net sales, with the U.S. comprising roughly half. He said Atea believes adoption of test-and-treat, combined with what it views as a best-in-class profile—short duration, low drug-drug interactions, and dosing convenience—could support expanded diagnosis and treatment among the roughly four million people the company said are living with HCV in the U.S.

Sommadossi also discussed commercialization mechanics, saying U.S. prescribing is concentrated among roughly 6,000 prescribers who account for 80% of direct-acting antiviral prescriptions. He said Atea believes it could commercialize with a focused specialist sales force of about 75 to 100 representatives at an estimated fully loaded cost of $25 million to $30 million. He also described planned packaging as two tablets once daily in blister packs, with cartons designed for 30-day reimbursement cycles.

Hepatitis E: new candidate selection and early development plan

Atea also highlighted a new HEV program aimed at immunocompromised patients in developed markets, focusing on foodborne transmission. Sommadossi said there is no approved treatment for hepatitis E and pointed to risk in solid organ transplant recipients, hematopoietic stem cell transplant patients, and individuals with hematologic malignancies. He described current approaches as reducing immunosuppression—raising rejection risk—or off-label ribavirin, which he said has toxicity and roughly 60% cure rates.

The company announced it has selected AT-587 as a clinical candidate. Sommadossi said the selection was based on in vitro profile and described activity across genotypes, including against a ribavirin resistance-associated substitution. He also said the company has animal data in monkeys and rats showing activation to the active triphosphate and drug exposure higher than bemnifosbuvir, and cited a “very clean” in vitro safety profile. IND-enabling GLP toxicology studies are underway, and Sommadossi said the company anticipates filing an IND and a CTA in Europe in Q2, followed by a proof-of-concept study.

In Q&A, Sommadossi said the proof-of-concept primary endpoint will be cure—no detectable virus 12 weeks after stopping treatment—using a Phase Ib approach that begins with a 12-week treatment duration and multiple dose levels. He said the company expects to know quickly whether the drug is potent and suggested a small proof-of-concept sample size, with viral kinetics modeling used to help predict time to cure and inform whether future studies require 12 or 24 weeks of therapy.

Financial position

Sommadossi said Atea ended December with a balance sheet in excess of $300 million in cash and investments and projected a cash runway through 2027 and into early 2028, which he said should support completion of the Phase 3 HCV program and advancement of the HEV program.

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.