Atea’s hepatitis C asset matches Gilead’s Epclusa in phase 3 trial

 Atea Pharmaceuticals’ hepatitis C prospect has matched Gilead’s Epclusa in a phase 3 trial, keeping the biotech barreling toward a second readout for its shorter, simpler treatment regimen. 

Boston-based Atea ran the pivotal C-Beyond study to compare its once-daily fixed-dose combination of bemnifosbuvir and ruzasvir (BEM/RZR) to Gilead’s incumbent hepatitis C drug. Gilead sells the product, a once-daily fixed-dose combination of sofosbuvir and velpatasvir, as Epclusa. The clinical trial enrolled 905 treatment-naive patients, including 184 people with cirrhosis. 

At Week 24, BEM/RZR achieved a 93.9% sustained virologic response (SVR) rate versus 94.8% for Epclusa, hitting the trial’s primary endpoint of statistical non-inferiority. An eight-week course of BEM/RZR matched the SVR achieved by a 12-week course of Epclusa in the 721 patients without cirrhosis. Patients with cirrhosis all received 12 weeks of treatment, with BEM/RZR again matching Epclusa in the subpopulation.

The pivotal readout achieved all the objectives that Atea management had previously outlined, William Blair analysts said in a note to investors. As well as showing non-inferiority to Epclusa in the modified intent-to-treat population favored by the FDA, BEM/RZR matched Gilead’s product in the per-protocol analysis preferred by the European Medicines Agency. 

Atea’s other phase 3 trial, C-Forward, is using the per-protocol population for its primary endpoint. Data from the second study, which enrolled patients outside North America, are due early next year and will complete the global regulatory submission package. 

An eight-week treatment period in non-cirrhotic patients is part of Atea’s positioning of BEM/RZR in a space served by AbbVie and Gilead. AbbVie’s hepatitis C drug Mavyret is given (PDF) for eight weeks in cirrhotic and non-cirrhotic patients but, unlike BEM/RZR and Epclusa, is only taken with food. Atea sees the favorable drug-drug interaction profile of BEM/RZR as another differentiator against the incumbents. 

Showing superiority over Epclusa would have further strengthened Atea’s hand, but that outcome was a long shot. In a note to investors back in April, William Blair analysts said they didn’t view superiority over Epclusa as the most likely scenario. 

Atea shares rose 2.3% to $4.93 in premarket trading Tuesday. With a market cap of $386 million before the phase 3 readout, Atea is only trading a little above the $256 million it had in the bank at the end of March. William Blair analysts pointed to the valuation to argue Atea is “a meaningfully underappreciated story” in a market that continues to support blockbuster sales. 

Sales of Gilead’s hepatitis C blockbusters Harvoni and Sovaldi peaked at $19.1 billion in 2015. Since then, the clearance of pent-up demand—which drove explosive sales growth—and intensifying competition have shrunk Gilead’s hepatitis C business. Even so, Gilead reported blockbuster hepatitis C sales last year. AbbVie’s rival hepatitis C drug Mavyret also delivered another year of blockbuster sales in 2025. 

https://www.fiercebiotech.com/biotech/ateas-hepatitis-c-asset-matches-gileads-epclusa-phase-3-trial