Regeneron Presents New Phase 3 Analyses Showing a Single Dose of REGEN-COV (casirivimab and imdevimab) Provides Long-term Protection Against COVID-19

Regeneron announced additional positive results from a Phase 3 trial which assessed use of a single dose of investigational REGEN-COV (1,200 mg administered via 4 subcutaneous injections) to prevent COVID-19 in uninfected individuals. REGEN-COV was able to reduce the risk for SARS-CoV-2 infection by 81.6% during the second to eighth month follow-up period and maintained the 81.4% risk reduction rate seen in in the first month. Initial data were published in The New England Journal of Medicine in September. 

REGEN-COV is composed of two monoclonal antibodies that block the infectivity of SARS-CoV-2 using the company’s VelociSuite and VelocImmune technologies. 

The double-blind, placebo-controlled trial enrolled people who lived in the same household as an individual who was diagnosed with SARS-CoV-2 within the prior 4 days. During the trial, participants were tested weekly for SARS-CoV-2 during the initial month (4 weeks), as part of the primary analyses. Following this, from months 2-8 (week 5 to week 32), participants were to be tested if they developed any COVID-19 symptoms.

Per the previously published data, the trial met its primary endpoint, reducing the risk of COVID-19 (i.e., laboratory-confirmed symptomatic SARS-CoV-2 infections) by 81.4% within 1 month of receiving REGEN-COV. The new results are from a pre-specified analysis for the following 7 months, throughout which an additional 45 symptomatic infections occurred. This includes results from 1,683 people who were not infected with SARS-CoV-2 and did not have antibodies for SARS-CoV-2 (seronegative) at baseline. During this time period, REGEN-COV continued to prevent infection, without requiring additional doses. In addition to the 81.6% risk reduction, data showed an 81.5% reduced risk of developing COVID-19 at any time during the 8 months after receiving REGEN-COV. In addition, during the 8-month assessment period, 0 subjects in the REGEN-COV group were hospitalized due to COVID-19, compared to 6 in the placebo group. 

The FDA has granted Emergency Use Authorization to REGN-COV for the treatment and post-exposure prophylaxis in certain high risk individuals.

In October the FDA accepted a BLA for REGN-COV for Priority Review and assigned a target action date of April 13, 2022. 

About the REGEN-COV Antibody Cocktail

REGEN-COV (casirivimab and imdevimab) is a cocktail of two monoclonal antibodies that was designed specifically to block infectivity of SARS-CoV-2, the virus that causes COVID-19, using Regeneron’s proprietary VelocImmune® and VelociSuite® technologies. The two potent, virus-neutralizing antibodies that form the cocktail bind non-competitively to the critical receptor binding domain of the virus’s spike protein, which diminishes the ability of mutant viruses to escape treatment and protects against spike variants that have arisen in the human population.