New England Journal of Medicine Publishes Positive Phase 3 Trial Results for REGEN-COV (casirivimab and imdevimab) to Prevent SARS-CoV-2 Infection

Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) today announced that the New England Journal of Medicine(NEJM) published positive detailed results from a Phase 3 trial that assessed the ability of REGEN-COV™ (casirivimab and imdevimab) to prevent COVID-19 infection among household contacts of SARS-CoV-2 infected individuals. The trial met its primary endpoint, reducing the risk of symptomatic infections by 81% (p<0.001), with a 93% reduction of symptomatic infections after the first week, and no dose-limiting toxicities observed.

"This peer-reviewed NEJM publication demonstrates that REGEN-COV provides rapid and robust protection to prevent SARS-CoV-2 infection, and follows data showing that REGEN-COV maintains effectiveness against all variants of concern," said George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer at Regeneron. "Despite the increased uptake of vaccines, SARS-CoV-2 has not been eradicated. In addition, growing evidence suggests that a substantial number of individuals, such as the immunocompromised, will not respond satisfactorily to vaccines. Thus, we believe there is a significant need for complementary medicines such as REGEN-COV to help prevent the spread of SARS-CoV-2 infection, particularly in these immunocompromised patients."

Regeneron previously announced initial results from the Phase 3 trial, which was jointly run with the COVID-19 Prevention Trials Network (CoVPN) National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH).

The robust REGEN-COV development program has reported positive Phase 3 trial results across the spectrum of COVID-19 infection, from prevention to hospitalization:

• Prevention of symptomatic infection in asymptomatic household contacts of SARS-CoV-2 infected individuals (both uninfected contacts as detailed in today's publication, and infected contacts)

• Treatment of non-hospitalized patients already infected with SARS-CoV-2

• Treatment of certain patients hospitalized due to COVID-19 infection, including the RECOVERY trial

In the U.S., REGEN-COV is currently authorized 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. Post-exposure prophylaxis with REGEN-COV is not a substitute for vaccination against COVID-19. REGEN-COV is not authorized 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.

REGEN-COV use is increasing across the U.S. following the latest surge, with recent weekly orders surpassing 50,000 doses. In addition to the increasing proportion of patients who now receive REGEN-COV, Regeneron continues to work to ensure all medical supply providers and people who may benefit from this important therapy are aware of its availability.

Multiple analyses, including a recent publication in Cell, have shown that REGEN-COV retains potency against the main variants of concern circulating within the U.S., including Delta (B.1.617.2; first identified in India), Gamma (P.1; first identified in Brazil) and Beta (B.1.351; first identified in South Africa). Consequently, REGEN-COV remains available for use across the U.S., and Regeneron will continue actively monitoring the potency of REGEN-COV against emerging variants.

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 Trial

The Phase 3 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. All participants were tested for SARS-CoV-2 at baseline using a RT-qPCR test from nasopharyngeal swabs and for the presence of antibodies using serum antibody testing. Participants were randomized (1:1) to receive either 1 dose of REGEN-COV (1,200 mg) or placebo, administered via 4 subcutaneous injections.

Among the 1,505 people included in the primary analysis, as they were not infected with SARS-CoV-2 and did not have antibodies for SARS-CoV-2 (seronegative) at baseline, 41% identified as Hispanic/Latino and 9% identified as Black/African American. In total, approximately 75% of participants had at least one known factor that put them at high risk of suffering severe consequences from COVID-19, as defined in the EUA fact sheet. In addition, 34% were obese and 38% were aged ≥50 years (median age: 34 years; range: 12-92 years).

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 is currently available via emergency or temporary pandemic use authorizations in more than 20 countries, including in the U.S., European Union, India, Switzerland and Canada, and is also fully approved in Japan.