Single Dose of Regen-Cov Provides Long-Term Protection Against COVID-19

Single dose of REGEN-COV (1,200 mg subcutaneous) reduced the risk of COVID-19 by 81.6% during the pre-specified follow-up period (months 2-8), maintaining the 81.4% risk reduction previously reported during month 1

During the 8-month assessment period there were 0 hospitalizations for COVID-19 in the REGEN-COV group and 6 in the placebo group

The fully human antibodies in REGEN-COV were developed to provide long-lasting protective effects without any artificial mutations or sequences

Regeneron Pharmaceuticals, Inc. announced additional positive results from a Phase 3 trial jointly run with the National Institute of Allergy and Infectious Diseases (NIAID), 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. The new analyses show REGEN-COV reduced the risk of contracting COVID-19 (i.e., laboratory-confirmed symptomatic SARS-CoV-2 infections) by 81.6% during the pre-specified follow-up period (months 2-8), maintaining the 81.4% risk reduction during the first month after administration, which was previously reported in The New England Journal of Medicine.

“Today’s new data demonstrate how a single dose of REGEN-COV can help protect people from COVID-19 for many months after administration,” said Myron S. Cohen, M.D., 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. “These results demonstrate that REGEN-COV has the potential to provide long-lasting immunity from SARS-CoV-2 infection, a result particularly important to those who do not respond to COVID-19 vaccines including people who are immunocompromised.”

In results previously published, 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 (p<0.0001). The new results released today describe a pre-specified analysis for the following 7 months, throughout which an additional 45 symptomatic infections occurred. During this time period, REGEN-COV continued to prevent infection, without requiring additional doses. Compared to placebo (n=842), people who received a single dose of REGEN-COV (n=841) experienced:

81.6% reduced risk of developing COVID-19 during the pre-specified follow-up period, between months 2-8 (7 REGEN-COV, 38 placebo; 95% confidence interval [CI]: 59.8%, 91.6%; nominal p<0.0001).
81.5% reduced risk of developing COVID-19 at any time during the 8 months after receiving REGEN-COV (20 REGEN-COV, 108 placebo; 95% CI: 70.6%,88.4%; nominal p<0.0001).
During the 8-month assessment period, 0 individuals in the REGEN-COV group were hospitalized due to COVID-19, compared to 6 individuals in the placebo group (1 person in the first month; 5 people during months 2-8). There were no deaths due to COVID-19 in any treatment group during the 8-month assessment period, and there were no new safety signals identified for REGEN-COV.

The trial, which was fully enrolled in early 2021, allowed participants to become vaccinated if they wished once the primary efficacy treatment period (month 1) was complete. Vaccination rates during the months 2-8 assessment period were balanced, with 34.5% (n=290) of the REGEN-COV group and 35.2% (n=296) of the placebo group receiving at least 1 COVID-19 vaccine dose by the end of the 8-month assessment period.

Through an innovative trial design, researchers were able to demonstrate the impact of REGEN-COV in high-risk household transmission settings (month 1, both pre- and post-exposure prophylaxis), as well as after the immediate risk of household infection had subsided (months 2-8, pre-exposure prophylaxis), when most infections were presumably acquired in the broader community. During the initial high-risk period related to household transmission, the rate of COVID-19 (in the absence of protection with REGEN-COV) was 13-fold higher than during the subsequent period of ongoing transmission: during month 1, the rate of COVID-19 in the placebo group was 8.3% per month; and during months 2-8 it decreased to 0.6% per month on average.

“In this trial, a single dose of REGEN-COV provided long-term protection against COVID-19, including times of particularly high risk from household exposure, and in the longer-term during ongoing broader exposure,” said George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer at Regeneron. “These data add to the increasing body of evidence supporting use of REGEN-COV to prevent COVID-19 in uninfected individuals, which may be especially useful for the many immunocompromised people who do not respond adequately to vaccines and remain ‘prisoners of the pandemic.’ With infections still occurring despite widespread vaccination, the immunocompromised face an ongoing risk of encountering the virus during their daily lives. We intend to rapidly share these additional data with regulatory authorities to help those in most need of protection from COVID-19.”

REGEN-COV is currently authorized in the U.S. to treat people who are at high risk of serious consequences from COVID-19 infection who are either already infected (non-hospitalized) or in certain post-exposure prophylaxis settings. In the U.S., REGEN-COV is not authorized as a substitute for vaccination against COVID-19, or for pre-exposure prophylaxis for prevention of COVID-19, or for use in patients who are hospitalized due to COVID-19 or require oxygen therapy, or for people currently using chronic oxygen therapy because of an underlying comorbidity who require an increase in baseline oxygen flow rate due to COVID-19. REGEN-COV has not been approved by the Food and Drug Administration (FDA), but is currently authorized for the duration of the declaration that circumstances exist justifying the authorization of the emergency uses under section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner.

The development and manufacturing of REGEN-COV have been funded in part with federal funds from the Biomedical Advanced Research and Development Authority (BARDA), part of the U.S. Department of Health and Human Services’ Office of the Assistant Secretary for Preparedness and Response, under OT number: HHSO100201700020C.

Regeneron is collaborating with Roche to increase global supply of the antibody cocktail, with Roche primarily responsible for development and distribution outside the U.S. Regeneron and Roche share a commitment to making the antibody cocktail available to COVID-19 patients around the globe and will support access in low- and lower-middle-income countries through drug donations to be made in partnership with public health organizations.

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, as detailed in Cell and Science.

REGEN-COV has not been approved by the FDA, but is currently authorized in the U.S. for the treatment and post-exposure prophylaxis in certain high risk individuals. This authorization is for the duration of the declaration that circumstances exist justifying the authorization of the emergency uses under section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner. Additional information about REGEN-COV in the U.S. is below (authorized uses and important safety information).

In October, the U.S. FDA accepted for priority review the first of two Biologics License Applications (BLAs) for REGEN-COV to treat COVID-19 in non-hospitalized patients and as prophylaxis in certain individuals. The second BLA submission will focus on those hospitalized because of COVID-19, and is expected to be completed later this year.

Emergency or temporary pandemic use authorizations are currently in place in more than 40 countries, including the U.S., several European Union countries, India, Switzerland and Canada, and the antibody cocktail is fully approved in Japan and conditionally approved in the UK.