HealthDay News — Among patients hospitalized with COVID-19, the efficacy and safety of the SARS-CoV-2 neutralizing monoclonal antibody bamlanivimab varies according to whether endogenous neutralizing antibodies (nAbs) are present, according to a study published online December 21 in the Annals of Internal Medicine.

Jens D. Lundgren, MD, from the University of Copenhagen in Denmark, and colleagues recruited 314 hospitalized patients with COVID-19 without end-organ failure and randomly assigned them to receive either bamlanivimab or placebo (163 and 151, respectively). At entry, 50% had evidence of production of anti-spike nAbs; 50% had SARS-CoV-2 nucleocapsid plasma antigen levels 1000 ng/L or greater. This trial was stopped prematurely because of futility, and the results of an a priori-defined subgroup analysis are reported here.

The researchers found that the median time to sustained recovery was 19 days and was similar in the bamlanivimab and placebo groups (subhazard ratio [sHR], 0.99; 95% CI, 0.79 to 1.22; sHR over 1 favors bamlanivimab). Among those without nAbs at entry, the sHR was 1.24 (95% CI, 0.90 to 1.70), while among those with nAbs, the sHR was 0.74 (95% CI, 0.54 to 1.00; nominal P for interaction, 0.018). Those with plasma antigen or nasal viral RNA levels above median at entry had an sHR greater than 1; sHR was greatest among those without antibodies and with elevated levels of antigen (sHR, 1.48 [95% CI, 0.99 to 2.23]) or viral RNA (sHR, 1.89 [95% CI, 1.23 to 2.91]). For the composite safety outcome, hazard ratios (less than 1 favored bamlanivimab) also varied by serostatus at entry (0.67 [95% CI, 0.37 to 1.20] and 1.79 [95% CI, 0.92 to 3.48] for those without and with nAbs, respectively).

“Treatment benefit and harm from bamlanivimab compared with placebo differed according to the presence of nAbs at study entry, with possible benefit in patients who were seronegative with high levels of plasma antigen or nasal viral RNA,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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