Atea Pharmaceuticals announces 2023 strategic priorities

Atea Pharmaceuticals provided an update on the company’s clinical development programs for 2023, including its strategic priorities and expectations for achievement of a variety of milestones. Bemnifosbuvir for COVID-19: SUNRISE-3 Global Phase 3 Registrational Study of Bemnifosbuvir in High-Risk Non-Hospitalized Patients with COVID-19: Patient enrollment continues in the randomized, double-blind, placebo-controlled, global Phase 3 SUNRISE-3 study evaluating bemnifosbuvir or placebo administered concurrently with locally available standard of care. The study is designed to enroll at least 1,500 high-risk, non-hospitalized patients with mild or moderate COVID-19, with an expected global footprint of approximately 300 clinical trial sites in the United States, Europe, Japan and rest of the world. Patients will be randomized 1:1 to receive either bemnifosbuvir 550 mg twice-daily plus locally available SOC or placebo BID plus locally available SOC for five days. An interim analysis is expected to be conducted in the second half of 2023. This trial is comprised of two patient population cohorts derived from the type of SOC received. These are 1) "Supportive Care Population" and bemnifosbuvir is evaluated as monotherapy and 2) "Combination Antiviral Population" which will assess combination therapy being bemnifosbuvir plus SOC if the SOC includes treatment with other COVID-19 antivirals. The primary endpoint of the study is all-cause hospitalization or death through Day 29 in the supportive care population in at least 1,300 patients. Secondary endpoints in each cohort include: COVID-19 complications, medically attended visits, symptom rebound / relapse and viral load rebound. The patient population will consist of those at the highest risk for disease progression, including patients greater than or equal to 80 years old, patients greater than or equal to 65 years old with greater than or equal to one major risk factor, and immunocompromised patients greater than or equal to 18 years old, all regardless of COVID-19 vaccination status. COVID-19 Program for Second Generation Protease Inhibitors: As part of a multipronged approach against COVID-19, Atea is advancing an internal program focused on the discovery of second-generation protease inhibitors that have clinical profiles appropriate for combination with bemnifosbuvir for the treatment of COVID-19. Atea’s target profile for a protease inhibitor is a compound that is highly potent, has a favorable safety profile with limited drug-drug interactions and does not require a pharmacokinetic booster. The lead optimization of compounds is ongoing for the selection of a candidate that will next enter preclinical toxicology studies. Atea’s goal for this program is to file an investigational new drug application / clinical trial application for a lead compound at the end of 2023. The combination of bemnifosbuvir with the protease inhibitor nirmatrelvir was examined in vitro in an HCoV-229E surrogate model and results indicated an additive antiviral effect. These data support the potential benefit of the combination of bemnifosbuvir and a protease inhibitor for the treatment of SARS-CoV-2 infection. AT-752 Program Update for DengueGlobal Phase 2 Dengue Study and Human Challenge Trial: Patient enrollment has been completed for the first cohort in the global Phase 2 DEFEND-2 trial of AT-752 for the treatment of dengue. The randomized, double-blind, placebo-controlled study is designed to evaluate multiple doses of AT-752 in three distinct cohorts and may enroll up to 60 adult patients infected with dengue. The primary objective of the study is to assess antiviral activity, with change from baseline dengue virus viral load as the primary endpoint. In addition, patient enrollment has been completed for the dengue human challenge model. This trial is designed to evaluate the effect of AT-752 in healthy volunteers who were challenged with an attenuated DENV-1 virus strain after receiving AT-752 or placebo. Analysis of data from both studies is underway and proof-of-concept results are expected in the first quarter of 2023. Hepatitis C Virus Program Update: Phase 2 HCV Combination Program: Regulatory submissions for the Phase 2 combination study of bemnifosbuvir and ruzasvir are ongoing. Atea expects to initiate patient dosing of the Phase 2 study during the second quarter of 2023 with initial data anticipated in the fourth quarter of 2023. This study will enroll approximately 280 HCV-infected, direct-acting antiviral naive patients across all genotypes, including a lead-in cohort of approximately 60 patients.Patients will be administered 550 mg bemnifosbuvir in combination with180 mg ruzasvir once-daily for eight weeks. The primary endpoints of the study are safety and sustained virologic response at Week 12 post-treatment. Other virologic endpoints include virologic failure, SVR at Week 24 post-treatment and resistance. Studies conducted by Atea have shown in vitro synergy from the combination of bemnifosbuvir and RZR in inhibiting HCV replication. In January 2022, Atea announced that it had obtained exclusive worldwide rights to develop, manufacture and commercialize RZR, an oral NS5A inhibitor, through a license agreement with Merck.