Regeneron Pharmaceuticals has announced changes to the Phase 3 trial assessing investigational REGEN-COV™ (casirivimab with imdevimab) in non-hospitalized patients (outpatients) with COVID-19, following recommendations from the Independent Data Monitoring Committee (IDMC). The IDMC found clear clinical efficacy on reducing the rate of hospitalization and death with both the 1,200 mg and 2,400 mg doses of REGEN-COV compared to placebo, and recommended stopping enrollment into the placebo group.
Regeneron is following the IDMC recommendation and will immediately stop enrolling patients in the placebo group. The trial will continue to enroll patients into both the 1,200 mg and 2,400 mg REGEN-COV treatment groups. The company has not yet had access to any of the unblinded data, including the relative treatment benefit of the 1,200 mg and 2,400 mg doses, and will share detailed results when available in March 2021.
"We appreciate the time and guidance of the IDMC and are extremely grateful to the thousands of patients and investigators who have participated in this more than 8,000-patient clinical trial," said David Weinreich, M.D., Executive Vice President and Head of Global Clinical Development at Regeneron. "REGEN-COV is now available in the U.S. to indicated high-risk non-hospitalized patients under an Emergency Use Authorization, and we hope to submit these results as part of a full Biologics License Application."
"In addition to the clear-cut efficacy that the IDMC has observed in this trial, it's reassuring that preclinical data from our labs and independent researchers show that REGEN-COV effectively neutralizes emerging strains of the virus, which are becoming increasingly common," said George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer at Regeneron. "Our cocktail approach using two functionally-independent antibodies safeguards against variants that may impact potency to a single antibody."
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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.
REGEN-COV (casirivimab with imdevimab) is a cocktail of two monoclonal antibodies (also known as REGN10933 and REGN10987) and was designed specifically to block infectivity of SARS-CoV-2, the virus that causes COVID-19. 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 Science.
In November 2020, REGEN-COV received Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA) for the treatment of mild to moderate COVID-19 in adults, as well as in pediatric patients at least 12 years of age and weighing at least 40 kg, who have received positive results of direct SARS-CoV-2 viral testing and are at high risk for progressing to severe COVID-19 and/or hospitalization. The clinical evidence from Regeneron's outpatient trial suggests that monoclonal antibodies such as casirivimab and imdevimab have the greatest benefit when given early after diagnosis and in patients who are seronegative and/or who have high viral load. The criteria for 'high-risk' patients are described in the Fact Sheet for Healthcare Providers. In the U.S., REGEN-COV is not authorized 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 (casirivimab with imdevimab) is an investigational combination therapy and has been authorized by FDA for the emergency use described above. REGEN-COV is not FDA approved for any use and its safety and effectiveness has not yet been established for the treatment of COVID-19.