Committed to the discovery, development and commercialization of oral direct-acting antiviral therapies.



Originating from our nucleos(t)ide discovery capabilities, bemnifosbuvir (AT-527) is an oral direct-acting antiviral being evaluated in SUNRISE-3, a global Phase 3 registrational trial for the treatment of COVID-19. Bemnifosbuvir targets the SARS-CoV-2 RNA polymerase (nsp12), a highly conserved enzyme that is unlikely to change as the virus mutates and new variants continue to emerge. This enzyme is responsible for both transcription and replication of SARS-CoV-2. Bemnifosbuvir has a unique mechanism of action, with dual targets consisting of inhibition of RNA dependent RNA polymerase (RdRp) and nucleotityltransferase (NiRAN) inhibition, which has the potential to create a high barrier to resistance.


Bemnifosbuvir + ruzasvir

In addition to COVID-19, bemnifosbuvir is also being developed in a Phase 2 clinical trial in combination with ruzasvir, an NS5A inhibitor, for the treatment of hepatitis C virus (HCV). As single agents, both bemnifosbuvir and ruzasvir have demonstrated potent pan-genotypic antiviral activity against HCV.


Combining innovative discoveries with development expertise to advance antivirals with the potential to transform treatments for patients with serious viral diseases.

Atea is a clinical stage biopharmaceutical company working to address unmet medical needs with innovative oral antiviral therapies.

Advancing Oral Antiviral Therapies with Multibillion Dollar Market Opportunities


Long-term multibillion dollar market opportunity of approximately $8-10 billion annually

  • Continued demand for innovative oral treatments to address key limitations of current therapies

Hepatitis C (HCV)

Large and growing population suffering from chronic HCV — global market in 2022 was approximately $3.5 billion annually in net sales

  • 1.5 million new infections occurring globally per year
  • ~75% of diagnosed patients in the US are untreated

Innovative Therapies to Address Unmet Medical Needs


Executing global Phase 3 SUNRISE-3 trial evaluating bemnifosbuvir for treatment of COVID-19 in high-risk patients

  • Fast Track designation granted for development of bemnifosbuvir for COVID-19
  • SUNRISE-3 is targeting approximately 330 clinical sites in 30 countries
  • Q4’23-Q1’24: SUNRISE-3 first interim analysis expected

Hepatitis C (HCV)

Initiating Phase 2 combination trial for bemnifosbuvir + ruzasvir in HCV patients

  • Q2’23: First patient dosed
  • Q4’23: Initial results expected from lead-in cohort of 60 patients

Our science.

Leveraging our deep understanding of antiviral drug development, medicinal chemistry, biology, biochemistry and virology, we are discovering and developing novel product candidates to treat single stranded ribonucleic acid, or ssRNA, viruses, which are a prevalent cause of serious viral diseases. Currently, we are focused on the development of orally-available direct-acting antiviral agents for serious viral infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, and HCV.

A network of hubs and spokes is suspended, representing the idea of a modular platform.


Bemnifosbuvir has the potential to address unmet medical needs for COVID-19.

As the evolution of COVID-19 continues, oral direct-acting antivirals will continue to play an increasingly essential role worldwide. The value and global health impact of conveniently administered direct-acting antivirals is to rapidly inhibit viral replication in the early phase of infection, which has the effect of reducing disease progression.

COVID-19 remains a serious public health threat and there is an urgent need for new oral treatment options to address unmet medical needs and limitations of current therapies.

Bemnifosbuvir is an oral, direct-acting antiviral drug candidate that is being evaluated for COVID-19.

Unmet Medical Need

Limitations of Current Vaccines / Therapies


  • Waning immunity of vaccines / natural infection
  • Potential mismatch of vaccine booster to circulating variants
  • Failure to mount immune response to vaccines in some patients
  • No effective monoclonal antibodies for outpatient use
  • Limitations with authorized oral antivirals: drug-drug interactions, safety concerns


SUNRISE-3 Cohort for Registration

Bemnifosbuvir’s profile addresses key limitations of current therapies

  • Antiviral efficacy against all tested variants of concern
  • Low risk of drug-drug interactions
  • No mutagenicity or embryo-fetal toxicity (preclinical)
  • High barrier to resistance

Combination Therapy

SUNRISE-3 Combination Cohort to Inform Development Strategy

Developing combination therapy for specific COVID-19 patient populations unable to mount immune response

  • Additive benefit indicated in vitro with bemnifosbuvir + DAAs including protease inhibitors (PIs)
  • Advancing internal PI program for combination therapy with bemnifosbuvir


Follow our progress.

Updates on bemnifosbuvir, other Atea product candidates and company news.

Atea Pharmaceuticals Presents Promising Bemnifosbuvir and Ruzasvir Combination Data for the Treatment of Hepatitis C Virus at AASLD The Liver Meeting 2023

First Clinical Data for Coadministration of Bemnifosbuvir and Ruzasvir Show Combination Was Well Tolerated in a Phase 1 Study Plasma Pharmacokinetic (PK) Profiles of Bemnifosbuvir and Ruzasvir Were Not Affected by Food or Concomitant Dosing, Indicating Low Risk of Drug-Drug Interactions

Atea Pharmaceuticals Reports Third Quarter 2023 Financial Results and Provides Business Update

P atient enrollment continues in global Phase 3 SUNRISE-3 trial evaluating bemnifosbuvir for COVID-19; first interim analysis expected 1Q24 Phase 2 bemnifosbuvir and ruzasvir combination trial for hepatitis C (HCV) advances, initial results from 60-patient lead-in cohort expected 1Q24 Conference

Atea Pharmaceuticals Announces Participation at Upcoming Investor Conferences

BOSTON, Nov. 08, 2023 (GLOBE NEWSWIRE) -- Atea Pharmaceuticals, Inc. (Nasdaq: AVIR) (“Atea”), a clinical-stage biopharmaceutical company engaged in the discovery and development of oral antiviral therapeutics for serious viral diseases, today announced that members of the Atea management team will