Regeneron Pharmaceuticals announced results from a Phase 3 trial, which assessed the ability of REGEN-COV (casirivimab with imdevimab) to reduce the risk and burden of COVID-19 infection among household contacts of SARS-CoV-2 infected individuals, according to a news release.
The trial of the monoclonal antibody cocktail met its primary and key secondary endpoints, showing that REGEN-COV 1,200 mg administered subcutaneously reduced the risk of symptomatic infections by 81% in those who were not infected when they entered the trial.
The company also announced data from as separate Phase 3 trial (2069B) of recently infected asymptomatic COVID-19 patients, finding that REGEN-COV reduced the overall risk of progressing to symptomatic COVID-19 by 31% (primary endpoint), and by 76% after the third day. The trial also demonstrated that REGEN-COV shortened symptom duration and markedly reduced viral levels.
Both trials were run jointly with the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH).
The first trial focused on uninfected individuals without anti-SARS-CoV-2 antibodies or any COVID-19 symptoms, who lived in the same household as an individual who tested positive for SARS-CoV-2 within the prior 4 days. The trial enrolled 1,505 people who were not infected with SARS-CoV-2 at baseline and randomized to receive either 1 dose of REGEN-COV (1,200 mg) or placebo, administered as SC injections.
The second trial enrolled 204 individuals without any COVID-19 symptoms who tested positive for SARS-CoV-2 but did not have anti-virus antibodies at baseline and were randomized to receive either one dose of REGEN-COV (1,200 mg) or placebo.
The trial met all primary and key secondary endpoints. In addition to reducing the risk of symptomatic infections, the total number of weeks patients experienced symptoms was nearly cut in half (45%) with REGEN-COV, and the viral burden was reduced by more than 90%. While not included in the initial analysis plan, researchers also found that 0 REGEN-COV patients and 6 placebo patients were either hospitalized or visited the emergency room because of COVID-19 during the 29-day efficacy assessment period.
