Positive data for COVID-19 antibody cocktail

Positive initial casirivimab and imdevimab results in non-hospitalized COVID-19 patients were published in NEJM

December 17, 2020
DDN Staff

TARRYTOWN, N.Y.—Regeneron Pharmaceuticals, Inc. reported today that the New England Journal of Medicine (NEJM) has published initial clinical data from an ongoing seamless Phase 1/2/3 trial of the antibody cocktail casirivimab and imdevimab in non-hospitalized patients with COVID-19. Casirivimab and imdevimab are monoclonal antibodies (also known as REGN10933 and REGN10987, respectively) specifically designed to block infectivity of SARS-CoV-2.

“The peer-reviewed NEJM publication of our first set of clinical data in recently infected COVID-19 patients showed that casirivimab and imdevimab effectively reduced viral load and the need for medically-attended visits, with the greatest benefit in patients who had not yet mounted their own effective immune response or had high viral load at baseline,” noted Dr. David Weinreich, senior vice president and head of Global Clinical Development at Regeneron, as well as lead author of the article. “The investigational cocktail is now available to indicated high-risk U.S. patients under an Emergency Use Authorization, and we also continue a robust clinical development program.”

Back in September, Regeneron previously noted the initial results featured in this NEJM publication. The data came from the Phase 1/2 portion of the trial that enrolled 275 patients randomized 1:1:1 to receive 8 grams casirivimab and imdevimab (high dose, n=90), 2.4 grams casirivimab and imdevimab (low dose, n=92), or placebo (n=93). Approximately 56 percent of patients were Latino/Hispanic, 13 percent were Black/African American, and 64 percent had one or more underlying risk factors for severe COVID-19, including obesity (over 40 percent). And in October, Regeneron subsequently reported more prospective results in a total of 799 patients from the trial. 

In both analyses, a greater effect was observed in patients treated with the antibody cocktail who either did not have SARS-CoV-2 antibodies at baseline (sero-antibody-negative), or who had high viral load at baseline. As expected, a much higher proportion of sero-antibody-negative patients had high viral loads when they entered the trial. 

A smaller proportion of antibody cocktail-treated patients required medically-attended visits due to COVID-19 (inclusive of hospitalizations, urgent care or emergency room visits, and in-person physician or telemedicine visits) through day 29, compared to placebo. There was an even greater benefit on this endpoint among sero-antibody-negative patients.

In the initial 275 patients, rates of adverse events (AEs) were similar among groups. Serious AEs occurred in 2 placebo patients, 1 low-dose patient and 0 high-dose patients. AEs included infusion-related reactions (1 placebo patient, 0 low-dose patients, 2 high-dose patients) and hypersensitivity reactions (2 placebo patients, 0 low-dose patients, 1 high-dose patient).

“Building on these initial findings, we were gratified to recently report follow-on data from the next-stage analysis of this ongoing trial, which prospectively replicated these results in a rigorous and statistically significant manner. These follow-on data provided the first definitive prospective evidence demonstrating anti-viral activity for a treatment regimen now available for COVID-19, and also further documented the ability of this treatment to decrease the need for further medical attention. We are continuing to evaluate our antibody cocktail in this outpatient setting, as well as in late-stage trials in hospitalized patients and for prevention of infection, and will continue to share our findings as quickly as possible,” added Dr. George D. Yancopoulos, president and chief scientific officer at Regeneron.

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