Bemnifosbuvir (AT-527) Program Update for COVID-19
SUNRISE-3: Global Phase 3 Registrational Study of Bemnifosbuvir in High-Risk Non-Hospitalized Patients with COVID-19: Before year-end 2022, Atea expects to begin enrollment of a randomized, double-blind, placebo-controlled, global Phase 3 study evaluating bemnifosbuvir or placebo administered concurrently with locally available standard of care (SOC). The study is designed to enroll at least 1,500 high-risk, non-hospitalized patients with mild or moderate COVID-19, with a 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 (BID) plus locally available SOC or placebo BID plus locally available SOC for five days.
This trial will be comprised of two populations derived from the type of SOC received. These are 1) “Supportive care population” (the patient does not qualify for an authorized oral antiviral treatment or is in a region where oral antivirals are not locally available) which will assess bemnifosbuvir given as monotherapy (primary analysis) and 2) “Combination antiviral population” which will assess combination therapy being bemnifosbuvir plus SOC if the SOC includes treatment with other compatible COVID-19 antivirals (secondary analysis).
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 patient population 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 ≥ 80 years old, patients ≥ 65 years old with ≥ one major risk factor, and immunocompromised patients ≥ 18 years old, all regardless of COVID-19 vaccination status.
Bemnifosbuvir Retains Antiviral Activity Against Omicron Subvariants BA.4 and BA.5 In Vitro: AT-511, the free base of bemnifosbuvir, has been shown to be a potent inhibitor of SARS-CoV-2 in vitro. New results demonstrated that AT-511 retained potent antiviral activity against the SARS-CoV-2 Omicron subvariants BA.4 and BA.5. AT-511 has previously demonstrated in vitro potent antiviral activity against other variants of concern and/or of interest, including Alpha, Beta, Gamma, Epsilon, Delta and Omicron subvariants BA.1 and BA.2.
Advancing Multipronged Approach for COVID-19 for Future Preparedness
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 booster (e.g., ritonavir). The lead optimization of compounds is ongoing for selection of a candidate that will next enter preclinical toxicology studies.
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.
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