Regeneron’s Antibody Cocktail Reduces Hospitalization or Death by 70% in COVID-19 Patients

Regeneron Pharmaceuticals, Inc.’s (Tarrytown, NY, USA) investigational antibody cocktail of casirivimab and imdevimab reduced hospitalization or death by 70% in non-hospitalized patients with COVID-19 in Phase 3 trial.

Regeneron’s antibody cocktail REGEN-COV also significantly shortened the duration of symptoms by four days in the largest trial to date assessing a COVID-19 treatment in infected non-hospitalized patients. The definitive Phase 3 outcomes trial in high-risk non-hospitalized COVID-19 patients ("outpatients") met its primary endpoint, showing the investigational REGEN-COV significantly reduced the risk of hospitalization or death by 70% (1,200 mg intravenous and 71% (2,400 mg) compared to placebo. REGEN-COV also met all secondary endpoints in the Phase 3 outcomes trial, including the ability to reduce symptom duration. In addition, a companion Phase 2 trial showed that even the lowest doses tested (IV: 300 mg; subcutaneous: 600 mg) had significant viral load reductions over the first seven study days, comparable to the 2,400 mg and 1,200 mg IV doses.


A safety assessment was conducted on all available patient data up to day 169, and identified no new safety signals. Serious adverse events (SAEs) were largely related to COVID-19 and occurred in 1.1% of patients in the 1,200 mg group, 1.3% in the 2,400 mg group and 4.0% in the placebo group. There was one death in the 1,200 mg group, one death in the 2,400 mg group and five deaths in the placebo groups. All patients in this analysis had at least one risk factor, including obesity (58%), age 50 years (51%) and cardiovascular disease, including hypertension (36%). Approximately 35% of patients were Latino/Hispanic, 5% were Black/African American and the median age was 50 years (range: 18-96 years).

"This is a landmark moment in the fight against COVID-19 as this large well-controlled trial provides conclusive results demonstrating that REGEN-COV can dramatically reduce the risk of hospitalization and death in the outpatient setting," said Suraj Saggar, D.O., trial investigator and Chief of Infectious Disease at Holy Name Medical Center in Teaneck, New Jersey. "With so many people still getting infected, as well as recent data showing that REGEN-COV addresses emerging variants, these data underscore the need to rapidly adopt REGEN-COV as standard-of-care to offer high-risk patients their best chance to reduce serious consequences like hospitalization or death."

"With approximately 60,000 newly diagnosed individuals in the US every day and 40,000 still in the hospital because of COVID-19, we are committed to working with the government, healthcare providers and others to support rapid and widespread adoption of REGEN-COV in appropriate patients," said George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer at Regeneron. "We will discuss the new data with regulatory authorities and request that the 1,200 mg dose be rapidly added to the U.S. Emergency Use Authorization, in order for the anticipated REGEN-COV supply to be available to treat even more patients. These Phase 3 data will also form the basis of a full Biologics License Application."

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