The Food and Drug Administration (FDA) has extended the review period by 3 months for the Biologics License Application (BLA) for REGEN-COV® (casirivimab and imdevimab) for treatment of COVID-19 in nonhospitalized patients and as prophylaxis in certain individuals. 

The new Prescription Drug User Fee Act (PDUFA) target date is now July 13, 2022. The FDA extended the review period due to ongoing discussions associated with pre-exposure prophylactic use of REGEN-COV, for which the Company has submitted additional data from its completed prophylaxis trial. According to the Company, the FDA considered this a major amendment to the application.

REGEN-COV consists of 2 potent, virus-neutralizing antibodies that bind noncompetitively to the receptor binding domain of the SARS-CoV-2 spike protein, thereby blocking its interaction with the host cell. 

The FDA accepted for Priority Review the BLA for REGEN-COV in October 2021. The application is supported by data from two phase 3 trials ( Identifier: NCT04425629, NCT04452318), which included more than 6000 patients. The efficacy and safety of REGEN-COV was evaluated as a treatment for nonhospitalized patients with COVID-19, and to prevent symptomatic infections in asymptomatic household contacts of SARS-CoV-2 infected individuals.

Results from both trials showed that treatment with REGEN-COV reduced the risk of hospitalization or death and reduced the risk of symptomatic SARS-CoV-2 infection development compared with placebo.

In January 2022, the FDA revised the authorization for REGEN-COV to limit its use only to patients who are likely infected with or exposed to variants susceptible to these treatments. According to recent data, the treatment was found to be “highly unlikely to be active against the Omicron variant” and is not currently authorized for use in any US states, territories, and jurisdictions at this time.


US FDA extends review of Biologics License Application for REGEN-COV® (casirivimab and imdevimab) for treatment and prophylaxis of COVID-19. News release. Regeneron Pharmaceuticals, Inc. Accessed April 14, 2022.