Investigational HCV Therapy Demonstrates 98% Sustained Virologic Response at Week 4


Atea Pharmaceuticals announced topline data from their phase 2 trial showing a higher than expected efficacy for the study.

Boston-based Atea Pharmaceuticals recently announced results from its ongoing phase 2 trial, which showed its combination investigational antiviral, bemnifosbuvir (BEM, AT-527) and ruzasvir (RZR) for the treatment of hepatitis C (HCV) reached a 98% sustained virologic response at week 4 (SVR4). These topline data are part of the company’s phase 2 open label study of the 2 therapies.

Participants were administered 550 mg of bemnifosbuvir in combination with 180 mg of RZR once-daily for 8 weeks. According to Atea, preliminary data are being presented as they become available. SVR4 data was available from 52 of the 60 lead-in participants.

In addition to SVR4 as a clinical endpoint, the study's design is intended to substantially shorten the anticipated timeline for the completion of the phase 2 trial. Clinical trials of other direct acting antiviral therapy combinations have demonstrated that the SVR4 result is highly correlated with SVR12.

According to the company, the study is designed to enroll approximately 280 HCV-infected, direct-acting antiviral naive patients across all genotypes, including a 60 patient lead-in cohort.

“We are excited to share that the initial data from the phase 2 combination 8-week study showed a 98% SVR4, which exceeds our efficacy criterion of >90% for continuing the study,” Atea CEO Jean-Pierre Sommadossi, PhD, said in a statement. “While direct acting antivirals have transformed HCV treatment, substantial unmet needs still exist, and the rate of new and reinfection currently exceeds cure rates in the US where 2.4 million individuals are estimated to be infected. The key unmet needs identified by healthcare providers in market research recently conducted by Atea include shorter length of treatment with fewer contraindications, particularly drug-drug interactions.”

Atea is a clinical-stage biopharmaceutical company engaged in the development of oral antiviral therapeutics for viral diseases.

What You Should Know

Atea Pharmaceuticals revealed promising results from its ongoing phase 2 trial for the treatment of HCV.

The phase 2 trial is designed to enroll approximately 280 HCV-infected patients, including a 60-patient lead-in cohort.

Atea Pharmaceuticals provided an enrollment update for its COVID-19 trial, SUNRISE-3.

In a previous interview with Contagion, Atea said the combination of bemnifosbuvir and ruzasvir demonstrated potent in vitro synergistic antiviral activity and in vivo preclinical safety without adverse interactions.

Sommadossi expects to report further results this year. “Based on these data, we plan to imminently reinitiate enrollment to complete the phase 2 study and topline results are anticipated in the third quarter of 2024.”

COVID-19 Trial Update

In addition to its work with its HCV therapy, the company is also studying bemnifosbuvir for its COVID-19 programs. Atea also reported an enrollment update for it COVID-19 trial, and stated its phase 3 study, SUNRISE-3. Specifically, Atea announced they had enrolled 650 participants for SUNRISE-3, which is a global, multicenter, randomized, double-blind, placebo-controlled trial, designed to evaluate bemnifosbuvir or placebo administered concurrently with locally available standard of care (SOC).

The study has a large global footprint targeting approximately 300 clinical trial sites in the US, Europe, Japan and rest of the world. Patients are randomized 1:1 to receive either bemnifosbuvir 550 mg twice-daily (BID) or placebo BID for five days. SUNRISE-3 is the only Phase 3 program in high-risk COVID-19 patients with hospitalization as a primary endpoint.

This trial is comprised of 2 study populations based on the type of SOC received:

A.bemnifosbuvir as monotherapy (primary analysis), and

B.The “combination antiviral population,” assessing combination therapy if the SOC includes other compatible antiviral drugs against COVID-19 (secondary analysis).

The primary endpoint of the trial is all-cause hospitalization or death through Day 29 post-treatment in the monotherapy arm in 2200 patients. The trial includes 2 interim analyses by the DSMB to assess safety and futility, to be conducted after approximately 650 and 1350 evaluable patients, respectively, after completion of Day 29 post treatment in the monotherapy arm. Atea expects the interim analysis to be completed in March.


Atea Pharmaceuticals Announces Positive Initial Data from Phase 2 Study for Hepatitis C Virus (HCV) and Significant Enrollment Milestone for Phase 3 SUNRISE-3 Trial for COVID-19. Atea Pharmaceuticals press release. January 8, 2024. Accessed January 21, 2024.

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