Clinical and Virological Response to a Neutralizing Monoclonal Antibody for Hospitalized Patients with COVID-19

Abstract

BACKGROUND Bamlanivimab, a neutralizing monoclonal antibody given in combination with remdesivir, did not improve outcomes among hospitalized COVID-19 patients based on an early futility assessment. In this final study report, we evaluate an a priori hypothesis that greater benefit of bamlanivimab would be identified in those without detectable endogenous neutralizing antibody levels at study entry, especially if viral levels were high. METHODS Hospitalized COVID-19 patients were randomized to receive bamlanivimab (7000mg) or placebo and followed for 90 days for sustained recovery (home for 14 consecutive days); recovery rate ratios (RRRs) are cited. RESULTS Among 314 participants (163 on bamlanivimab and 151 on placebo), the median time to sustained recovery was 19 days and RRR=0.99 (95% CI: 0.79-1.22; p=0.89). At entry, 50% evidenced production of anti-spike neutralizing antibodies; 50% had SARS-CoV-2 nucleocapsid plasma antigen levels [≥] 1,000 ng/L. Among those without and with antibodies at study entry, the RRRs were 1.24 (95% CI: 0.90-1.70) and 0.74 (95% CI: 0.54-1.00) (p=0.02 for interaction). The RRRs were elevated for those with plasma antigen or nasal viral RNA levels above versus below median at entry, and was greatest for those without antibodies and with elevated antigen or viral RNA levels: 1.48 (95% CI: 0.99-2.23), 1.94 (1.25-3.00), respectively (p<0.05 for all interactions). Hazard ratios for safety outcomes also differed by serostatus at entry. CONCLUSIONS Sustained recovery after administration of bamlanivimab versus placebo differed by presence of neutralizing antibodies at study entry, especially if participants had markers of elevated viral replication. ClinicalTrials.gov number, NCT04501978.