Interim findings suggest antibody cocktail reduces viral load in patients with COVID-19
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Regeneron’s antibody cocktail reduced viral load in patients with COVID-19, according to preliminary findings from a small study published recently in The New England Journal of Medicine.
The REGN-COV2 cocktail displayed “a greater effect in patients whose immune response had not yet been initiated or who had a high viral load at baseline,” the authors wrote.
“Our analysis suggests that an antibody cocktail against SARS-CoV-2 can also be an effective antiviral therapy enhancing viral clearance and thus leading to improved outcomes, particularly in patients whose own immune response to the virus is slow to initiate,” Daniel M. Weinreich, PhD, professor of ecology and evolutionary biology at Brown University, and colleagues wrote. “Further studies, including the continuing phase 3 portion of this trial, are needed to confirm these effects.”
In November, the FDA issued an emergency use authorization (EUA) for REGN-COV2, which consists of the monoclonal antibodies casirivimab and imdevimab, for use in patients aged 12 years or older with a positive SARS-CoV-2 test who are at risk for progression to severe COVID-19.
The Infectious Diseases Society of America recommends against the routine use of another investigational monoclonal antibody regimen, bamlanivimab (Eli Lilly), which also received an EUA from the FDA in November, but it does not have a specific recommendation for the Regeneron products.
Weinreich and colleagues reported preliminary data from an ongoing double-blind, phase 1-3 trial being conducted among non-hospitalized adult patients with COVID-19. The study is supported by Regeneron and HHS’s Biomedical and Advanced Research and Development Authority (BARDA).
The analysis included results from 275 patients randomly assigned to receive either a placebo, 2.4g of REGN-COV2 or 8g of REGN-COV2. Weinreich and colleagues analyzed safety, time-weighted average changes in viral load from the baseline from day 1 to day 7, and the number of patients with one or more COVID-19-related medical visits through day 29.
Overall, the average difference in time-weighted change in viral load between both groups given REGN-COV2 vs. the placebo group on days 1 to 7 was -0.56 log10 copies/mL (95% CI, -1.02 to -0.11) among patients who had no antibodies at baseline, and -0.41log10 copies/mL (95% CI, -0.71 to -0.10) in the overall trial population, Weinreich and colleagues reported.
A total of 6% of patients given placebo and 3% of patients given REGN-COV2 reported at least one medically attended visit. In a subgroup of participants who were serum antibody-negative at baseline, the difference was larger: 15% in the placebo arm and 6% in the treatment arms reported a medically attended visit.
“An important limitation of this interim portion of our trial is that, although the analyses
according to antibody status were prespecified, no formal hypothesis testing was performed to control type I error; in addition, the analyses according to baseline viral load were post hoc,” the authors wrote. “These results should therefore be rigorously tested in the next analysis in this ongoing trial.”
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