Regeneron's COVID-19 antibody cocktail reduced the risk of COVID-19-associated hospitalization and death by 71 percent and lowered patients' viral loads faster than a placebo, according to results of a phase 3 clinical trial.
The findings were published Sept. 29 in The New England Journal of Medicine. From Sept. 24, 2020, to Jan. 17, 2021, Reneneron researchers randomly assigned 2,696 adult COVID-19 outpatients at high risk for severe illness to receive either the antibody treatment or a placebo through intravenous infusion.
Of the 1,355 patients who were given 2,400 milligrams of the antibody cocktail, 1.3 percent (18 people) were hospitalized or died from any cause after 28 days. Of the 1,341 patients who were given a placebo, 4.6 percent (62 people) were hospitalized or died.
Of the 736 patients who received 1,200 mg of the antibody treatment, 1 percent (7 people) were hospitalized or died. For the 748 patients in the placebo group, 3.2 percent (24 people) were hospitalized or died. The group that received the treatment was also less likely to require intensive care unit admission.
Symptoms among patients in the antibody group were resolved a median of four days faster than in the placebo group, regardless of dose. Additionally, both doses of the treatment lowered patients' viral load faster than a placebo.
Regeneron's antibody cocktail is a 1:1 combination of casirivimab and imdevimab. In November 2020, it received FDA emergency use authorization. The FDA revised its emergency use authorization July 30, allowing the treatment to be used as a post-exposure prophylaxis for COVID-19 in individuals who are at high risk for progression to severe COVID-19.