A monoclonal antibody cocktail developed by Regeneron and Roche dropped the risk of symptomatic COVID-19 by up to 76% after three days for recently infected individuals not yet experiencing symptoms, according to a press release posted Monday. The drug, REGEN-COV, also significantly reduced duration of symptoms and lowered viral levels, Regeneron said.
REGEN-COV, comprised of casirivimab with imdevimab, has already received emergency use authorization from the FDA in the U.S. Under the current EUA, the combo therapy is approved to treat non-hospitalized adults and adolescents with mild to moderate symptoms of COVID-19 and who are at high risk for developing severe symptoms or the need for hospitalization.
The currently authorized dosage is 1,200 mg of casirivimab and 1,200 mg of imdevimab administered together as a single infusion within 10 days of symptom onset.
The results announced Monday drew from a Phase 3 study involving 204 individuals who were randomly assigned to receive the drug via 1,200 mg injection or placebo.
“COVID-19 transmission often occurs via infected people who do not yet have symptoms, so it is critical that we rapidly diagnose and treat these individuals for their own health and to prevent transmission,” Dr. Katharine Bar, co-principal investigator of the trial and assistant professor of Medicine, Infectious Diseases, Hospital of the University of Pennsylvania, said in part in the release.
More specifically, the company noted a 45% drop in the number of weeks patients felt symptoms, and the viral burden was cut by over 90%.
Regeneron also announced separate, positive findings on REGEN-COV on Monday, indicating the 1,200 mg injection helped to tamp down symptomatic COVID-19 infections within households by 81%. Findings drew from 1,505 trial participants who were not infected when they entered the study.
“These findings are very encouraging and suggest that REGEN-COV is highly effective at preventing symptomatic COVID-19 in household contacts of SARS-CoV-2 infected individuals,” said Dr. Dan Barouch, Ph.D., co-principal investigator of the trial and director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center and professor of medicine at Harvard Medical School.
“These antibodies may be particularly useful in individuals who are not yet vaccinated, and may also have potential in those who are immunosuppressed and may not respond well to vaccines,” Barouch said in part.
Almost 10% of people living with an infected individual experienced symptomatic infection if they did not take the drug, according to Dr. Myron Cohen, who leads the monoclonal antibody efforts for the NIH-sponsored COVID Prevention Network (CoVPN) and is director of the Institute for Global Health & Infectious Diseases at the University of North Carolina at Chapel Hill.
While participants on placebo cleared symptoms in three weeks, those taking REGEN-COV saw symptoms clear in one week, the company said.
Regeneron intends to share the findings with the U.S. Food and Drug Administration to expand the currently authorized use “to include COVID prevention for appropriate populations, using a 1,200 mg subcutaneous dose,” the company said.
Fox News’ Alexandria Hein contributed to this report.