Virologic Response and Safety of Ibuzatrelvir, A Novel Severe Acute Respiratory Syndrome Coronavirus 2 Antiviral, in Adults With Coronavirus Disease 2019

Abstract

Background Despite effective vaccines and treatments for COVID-19, clinical burden persists. An unmet need exists for additional effective agents with safety profiles allowing use across a broad population. Ibuzatrelvir is an orally bioavailable SARS-CoV-2 Mpro inhibitor that has demonstrated in vitro antiviral activity and low potential for safety concerns, including drug-drug interactions. Methods This phase 2b, double-blind, randomized clinical trial enrolled US adults aged 18‒<65 years with symptomatic COVID-19 and no risk factors for severe disease. Participants were randomized 1:1:2:2 to receive 100, 300, or 600 mg ibuzatrelvir or placebo orally twice daily for 5 days. Nasopharyngeal specimens were collected on Days 1 (baseline), 3, 5, 10, 14, and 21; adverse events (AEs) were recorded through Day 33. The primary endpoint was change in SARS-CoV-2 RNA level (viral load [VL]) from baseline to Day 5 among participants with baseline VL ≥4 log10 copies/mL. Results Of 240 enrollees, 237 received ≥1 dose and 199 were included in the primary analysis. Placebo-adjusted least squares mean (80% CI) change from baseline in VL at Day 5 was significant across all doses: 100 mg, ‒0.7 (‒1.1, ‒0.3) log10 copies/mL, P=0.02; 300 mg, ‒0.8 (‒1.3, ‒0.3) log10 copies/mL, P=0.01; and 600 mg, ‒1.2 (‒1.5, ‒0.8) log10 copies/mL, P<0.0001. AEs occurred in similar percentages of participants across groups. No deaths from any cause or treatment-related serious AEs occurred through Day 33, and no participants reported dysgeusia. Conclusions All 3 ibuzatrelvir doses were associated with robust antiviral activity and an acceptable safety profile, supporting continued clinical development. Trial Registration Clinicaltrials.gov identifier: NCT05799495