Atea Pharmaceuticals (NASDAQ:AVIR) reported positive top-line results from its Phase III C-BEYOND trial of bemnifosbuvir/ruzasvir for chronic hepatitis C virus, saying the study met its primary and secondary endpoints against the standard-of-care regimen sofosbuvir/velpatasvir, marketed as Epclusa.
The company also said its second Phase III hepatitis C trial, C-FORWARD, has completed enrollment and is expected to report top-line results in early 2027. Atea ended the second quarter with $219.5 million in cash and marketable securities and said it expects its cash runway to extend through 2027.
Phase III C-BEYOND Results
Patients without cirrhosis received bemnifosbuvir/ruzasvir for eight weeks or sofosbuvir/velpatasvir for 12 weeks. Patients with compensated cirrhosis received 12 weeks of treatment in either arm.
In the modified intent-to-treat population, bemnifosbuvir/ruzasvir achieved a sustained virologic response rate of 93.9% at week 24, compared with 94.8% for sofosbuvir/velpatasvir. Atea said the result met the trial’s prespecified 5% non-inferiority margin. The modified intent-to-treat population included patients who received at least one dose, including those who discontinued treatment, did not adhere to the protocol or were lost to follow-up.
Among non-cirrhotic patients, the eight-week bemnifosbuvir/ruzasvir regimen produced a 93.5% sustained virologic response rate, compared with 94.6% for 12 weeks of sofosbuvir/velpatasvir. In patients with compensated cirrhosis, both arms reported a 95.4% response rate. Atea noted that these subgroups were not powered for statistical analysis.
Chief Medical Officer Arantxa Horga said the trial enrolled a population reflecting current treatment challenges in North America. More than half of participants reported injection drug use as the route of hepatitis C transmission, about 89% were taking concomitant medications, and two-thirds had a psychiatric disorder, according to the company.
Horga said adverse events were comparable between the treatment arms, with most treatment-emergent events mild to moderate. There were no serious adverse events attributed to either study drug and no early discontinuations attributed to treatment. The sofosbuvir/velpatasvir arm had three deaths, none of which were considered related to the study drug, while there were no deaths in the bemnifosbuvir/ruzasvir arm.
Second Trial and Regulatory Plans
Atea’s C-FORWARD study, conducted outside North America, enrolled more than 880 patients and is designed to support a broad pan-genotypic regulatory package. The study includes greater representation of genotypes 1b, 3, 4, 5 and 6 than C-BEYOND, management said.
Chief Executive Officer Jean-Pierre Sommadossi said C-FORWARD is expected to provide top-line data in early first-quarter 2027. Pending positive results, Atea anticipates submitting a New Drug Application to the Food and Drug Administration in the second quarter of 2027.
During the question-and-answer session, Sommadossi clarified that the modified intent-to-treat analysis will serve as the primary endpoint for the FDA in C-FORWARD, while the per-protocol analysis is the primary endpoint for the European Medicines Agency.
Atea said it believes bemnifosbuvir/ruzasvir could offer an eight-week regimen for non-cirrhotic patients, without a protease inhibitor, with low potential for drug-drug interactions and no food effect. Chief Development Officer Janet Hammond said the company expects broad compatibility with several categories of concomitant medicines, including certain HIV treatments, statins, immunosuppressants, digoxin and acid-reducing therapies.
Commercial Outlook
Chief Commercial Officer John Vavricka said the company sees an opportunity in the gap between newly diagnosed hepatitis C infections and the number of patients treated. According to Atea, about half of newly infected patients were treated in 2025, and the U.S. hepatitis C-infected population is approaching 4 million people.
Vavricka said Atea expects its regimen could be suited to a “test-and-treat” model, in which patients are diagnosed and begin treatment during the same visit. The company plans to offer both bottles and four-week blister packs, although Vavricka said payer requirements governing whether patients can receive the full course without a refill will vary by program and state.
Atea’s market research among high-volume direct-acting antiviral prescribers found that 76% said they would be extremely likely to prescribe bemnifosbuvir, according to the company. Management projected potential peak annual U.S. net revenue exceeding $700 million and said it expects pricing to be in line with existing branded hepatitis C regimens. The company also said it expects a focused commercial organization of roughly 75 to 100 personnel could reach most of the U.S. prescriber base.
Hepatitis E Program and Financial Position
In July, Atea initiated a first-in-human Phase I trial of AT-587, a potential direct-acting antiviral for chronic hepatitis E. The randomized, double-blind, placebo-controlled trial is being conducted in healthy volunteers and will assess safety, tolerability and pharmacokinetics through single-ascending-dose and multiple-ascending-dose phases, as well as a food-effect assessment.
Hammond said the company had completed the first cohort and was proceeding to the next cohort. Atea said there is currently no approved therapy for hepatitis E and that it is targeting proof of concept for AT-587 in 2027.
Chief Financial Officer Andrea Corcoran said research and development expense increased in the first six months of 2026 from a year earlier, driven primarily by external spending on the hepatitis C Phase III program and hepatitis E preclinical and clinical startup work. General and administrative expense declined, primarily due to lower salaries, wages and stock-based compensation.
The company said most spending in the second half of 2026 will remain directed toward completing C-FORWARD, preparing regulatory filings and conducting pre-launch activities for its hepatitis C 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.
