Atea Pharmaceuticals Presents New Drug-Drug Interaction Results Supporting Potential Best-in-Class Profile of the Regimen of Bemnifosbuvir and Ruzasvir for the Treatment of Hepatitis C Virus at EASL Congress 2026

Atea Pharmaceuticals, Inc. (Nasdaq: AVIR) (Atea or Company), a late-stage clinical biopharmaceutical company engaged in the discovery and development of oral antiviral therapeutics for serious viral diseases, today announced Phase 1 results which further demonstrate that the fixed-dose combination regimen of bemnifosbuvir and ruzasvir (BEM/RZR) for the treatment of hepatitis C virus (HCV) has a low risk of drug-drug interaction. These results support the use of BEM/RZR with commonly used medications, including the proton pump inhibitor (PPI) omeprazole and the cholesterol-lowering drug rosuvastatin. The Company is also presenting data demonstrating high in vitro antiviral potency and in vivo efficacy for AT-587, its potential first-in-class direct-acting antiviral (DAA) for the treatment of hepatitis E virus (HEV). These data are being presented at the European Association for the Study of the Liver (EASL) Congress 2026, taking place May 27-30th in Barcelona, Spain.

“These Phase 1 results reinforce the potential of the regimen of BEM/RZR to simplify treatment for patients and healthcare providers and address the evolving needs of today’s patients living with HCV,” said Jean-Pierre Sommadossi, PhD, Chief Executive Officer and Founder of Atea Pharmaceuticals. “Our market research has shown that most HCV patients in the US manage multiple medications concurrently, which can complicate care. The results being presented demonstrate that the regimen of BEM/RZR can be co-administered with PPIs and other commonly used medications without requiring dose adjustments. As we move toward topline Phase 3 results from C-BEYOND and C-FORWARD, these data give us continued confidence in the regimen’s potential to deliver a best-in-class profile for today’s patients living with HCV.”

HCV continues to be a significant global health burden despite the availability of DAAs. According to US healthcare providers who treat patients with HCV, approximately 80 percent of patients take multiple medications to manage comorbidities and drug-drug interactions are a significant concern in HCV treatment. As a result, a new treatment option offering a low risk of drug-drug interactions together with high efficacy and short treatment duration could meaningfully address patient needs and further the goal of HCV eradication.

“The data being presented for AT-587 demonstrate high in vitro antiviral potency and in vivo efficacy against HEV, underscoring its potential,” Dr. Sommadossi added. “There is a critical gap in the care of patients with chronic HEV with no approved therapies, leaving vulnerable populations including transplant recipients and other immunocompromised patients at risk for rapid disease progression to cirrhosis. Following the encouraging preclinical data, we look forward to advancing our potential first-in-class product candidate, AT-587, into a first-in-human study mid-year.”
In recent years, chronic HEV genotype 3 and 4 infections have been increasingly recognized as a potentially life-threatening viral infection in immunocompromised individuals — a population that includes solid organ and hematopoietic stem-cell transplant recipients, and patients with hematologic malignancies. In these vulnerable populations, chronic HEV can result in rapid progression to cirrhosis within three to five years. There is no approved antiviral therapy for HEV, and current off-label treatments have limited efficacy and tolerability, underscoring a clear and urgent unmet medical need.

 

Phase 1 Results for the Regimen of BEM/RZR Highlight Favorable Drug-Drug Interaction Profile for Treatment of HCV  

Poster ID: FRI-635
Title: Proton-pump inhibitor omeprazole did not affect the plasma pharmacokinetics of bemnifosbuvir and ruzasvir fixed-dose combination in healthy participants
Presenting Author: Xiao-Jian Zhou
Date and Time: Friday, May 29, 8:30 a.m.–5:00 p.m. CEST
A Phase 1 study in healthy adults (n=20) showed the regimen of BEM/RZR was generally safe and well-tolerated when administered alone or concomitantly with omeprazole, a commonly used medication among HCV-infected patients to treat stomach acid conditions. These results support co-administration of BEM/RZR with PPIs, which often reduce the solubility of DAAs, decreasing their absorption/bioavailability and negatively impacting DAA efficacy. Omeprazole dosed at 20 mg, a common dose for gastroesophageal reflux disease, did not affect plasma exposure to BEM/RZR. Omeprazole dosed at 40 mg administered two hours before BEM/RZR to allow maximal acid-suppressive effect only slightly reduced plasma exposure to BEM/RZR. Co-administered BEM/RZR did not meaningfully affect the pharmacokinetic (PK) profile of omeprazole.

Poster ID: FRI-636
Title: Bemnifosbuvir and ruzasvir administered as a fixed-dose combination have low potential to inhibit P-gp, BCRP or OATP1B1/3 mediated transport
Presenting Author: Xiao-Jian Zhou
Date and Time: Friday, May 29, 8:30 a.m.–5:00 p.m. CEST
A Phase 1 study in healthy adults evaluated interactions between the regimen of BEM/RZR and digoxin (n=18) or rosuvastatin (n=18), sensitive substrates of the drug transporters P-gp and BCRP/OATP1B1/1B3, respectively. These transporters are important for how drugs are absorbed, enter the liver and are cleared from the body. Results demonstrated that BEM/RZR administered with digoxin and rosuvastatin was well tolerated with all treatment-emergent adverse events mild in severity. A single dose of BEM/RZR slightly increased the plasma exposure of digoxin and rosuvastatin. With a geometric mean ratio of less than 2, BEM/RZR has low potential to exhibit clinically meaningful inhibition of these transporters. These results demonstrate that no dose adjustments are needed for drugs that are substrates of these transporters when co-administered with BEM/RZR.

 

AT-587 Results Demonstrate High In Vitro Antiviral Potency and In Vivo Efficacy Against HEV

Poster ID: TOP-631
Title: Discovery and preclinical profile of a first-in-class potent hepatitis E virus inhibitor AT-587
Presenting Author: Qi Huang
Date and Time: Thursday, May 28, 8:30 a.m.–5:00 p.m. CEST
Results presented support AT-587 as an oral nucleotide analog exhibiting promising preclinical antiviral potency against HEV. In vitro studies demonstrated that AT-587 is a potent inhibitor of HEV replication. Specifically, AT-587 was 30 to 150-fold more potent in vitro against HEV than sofosbuvir (SOF) and ribavirin, which is currently used off-label. AT-587 showed no toxicity in in vitro studies. AT-587 also demonstrated activity against flaviviruses, rubella and chikungunya.
In addition, new results showed that AT-587 inhibited HEV-3 activity in vivo. Using HEV-3-infected gerbil models, fecal samples from the treated groups had significantly lower HEV RNA levels than the control group. In addition, the viral loads in the liver and intestinal samples were significantly lower in the treated groups compared to control. Notably, AT-587 also retained high potency against ribavirin (G1634R) and SOF (A1343V) clinical resistance strains in vitro, further differentiating its profile from existing off-label treatment options.