FDA Authorizes Casirivimab and Imdevimab for COVID-19

An original version of this article was published to sister publication Contagion.

The US Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for Regeneron’s monoclonal antibodies, casirivimab and imdevimab, for the combined treatment of mild to moderate coronavirus 2019 (COVID-19).

This marks the third EUA for an investigational COVID-19 therapy, after remdesivir and baricitinib—another pair of therapies which have been observed to provide greater efficacy when combined for COVID-19.

The emergency authorization, granted on Saturday evening, allows for the intravenous (IV) cocktail to be used on adults and pediatric patients—at least 12 years old and at least 88 pounds—with positive SARS-CoV-2 viral testing results deemed to be at high risk for progression to severe COVID-19.

This patient population can include the those ≥65 years old or those who have chronic medical conditions, the FDA stressed in its EUA statement.

In supporting trial data included in the Regeneron application, casirivimab and imdevimab was observed in a double-blind, placebo-controlled assessment of 799 non-hopsitalized adults with mild to moderate COVID-19 symptoms. Investigators administered a single, equal-parts 2400mg IV infusion of the therapy to 266 patients, an equal-parts 8000 mg IV infusion to 267 patients, and a placebo to 266 patients.

Patients had been treated within 3 days of obtaining a positive SARS-CoV-2 viral test—a vital factor in the suggested efficacy of monoclonal antibodies in preventing severe COVID-19 progression.

Investigators observed for a primary endpoint of time-weighted mean viral load change from baseline. Viral load reduction in patients treated with casirivimab and imdevimab was greater in patients treated versus placebo at day 7. Additionally, just 3% of patients treated with the combined therapy visited a hospital or emergency department for COVID-19 progression within 28 days, versus 9% of placebo-treated patients.

That said, its safety and efficacy continues to be evaluated for COVID-19.

In a statement accompanying the indication, FDA commissioner Stephen M. Hahn, MD, emphasized the benefit of casirivimab and imdevimab in reducing COVID-19 severity—a comment which comes at a time when new daily cases are nearing 200,00 in the US, and hospital resources are becoming exhausted in concentrated areas.

“The FDA remains committed to advancing the nation’s public health during this unprecedented pandemic,” Hahn said. “Authorizing these monoclonal antibody therapies may help outpatients avoid hospitalization and alleviate the burden on our health care system.”