Glecaprevir/Pibrentasvir

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.

Atea Pharmaceuticals said Tuesday that its experimental hepatitis C virus (HCV) treatment went toe-to-toe against Gilead Sciences' established therapy Epclusa (sofosbuvir/velpatasvir) in a Phase III trial — and held its own. According to the company, its once-daily combination of bemnifosbuvir, a nucleotide analogue polymerase inhibitor, plus NS5A inhibitor ruzasvir (BEM/RZR) met the primary endpoint of statistical non-inferiority versus Epclusa in the C-BEYOND trial, and could allow for a shorter treatment alternative for many patients.In the 905-patient modified intent-to-treat population, BEM/RZR produced a sustained virologic response (SVR) rate of 93.9% at week 24, compared to 94.8% for Epclusa.Among patients without cirrhosis (n=721) who received an eight-week course of BEM/RZR, the regimen achieved a 93.5% SVR rate versus 94.6% for the 12-week Epclusa regimen. In patients with cirrhosis (n=184), both treatments produced a 95.4% SVR rate after 12 weeks. Atea said safety was comparable between treatment arms, with no drug-related serious adverse events or early treatment discontinuations.The study was conducted in the US and Canada; Atea said its drug showed robust SVR rates across HCV genotypes that predominate in North America.Antiviral market dynamicsStill, Morgan Stanley analysts suggested the commercial prospects for BEM/RZR could be dampened by competition from established HCV therapies. Atea's shares ticked down about 6% on Tuesday. "While comparable efficacy and potential advantages of a shorter treatment duration for most patients, low risk of drug-drug interactions and no food effect reinforce BEM/RZR's profile, we continue to expect focus on antiviral market dynamics for HCV, including Gilead's Epclusa and Abbvie's Mavyret (glecaprevir/pibrentasvir)," they said in a note to clients.That next data point will come from Atea's second Phase III trial, called C-FORWARD, evaluating BEM/RZR outside North America. That study, which has enrolled more than 880 patients across 17 countries, is expected to report topline results in early 2027."Looking ahead, we believe C-FORWARD will provide important additional insight into the regimen's efficacy across HCV genotypes which are less common in the US and Canada," said Janet Hammond, Atea's chief development officer.