Regeneron Pharmaceuticals, Inc. announced that a trial assessing investigational REGEN-COV™ (casirivimab and imdevimab) in patients hospitalized with COVID-19 met its primary endpoint. Trial results will be presented at IDWeek 2021, and show that REGEN-COV significantly reduced viral load in patients hospitalized with COVID-19 who entered the trial without having mounted their own antibody response (seronegative) and required low-flow or no supplemental oxygen (p=0.0172). The trial also had clinical results supportive of the much larger UK RECOVERY trial in hospitalized patients, with numeric improvements observed across all clinical endpoints assessed. REGEN-COV is an investigational medicine authorized by the U.S. Food and Drug Administration (FDA) under an emergency use authorization 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., it is not currently authorized in patients who are hospitalized due to COVID-19 infection. The trial, which was stopped due to slow enrollment after recruiting just over one third the patients originally planned, found that patients who received REGEN-COV (2,400 mg or 8,000 mg) in addition to standard-of-care (SOC) experienced numeric improvements across all clinical endpoints assessed, compared to SOC alone (placebo). Researchers did not observe any clinical difference between the two REGEN-COV doses (2,400 mg or 8,000 mg), or any serious or dose-dependent safety signals in REGEN-COV treated patients. In a safety analysis involving 2,007 patients (REGEN-COV=1,340, placebo=667) serious adverse events occurred in 21% REGEN-COV patients (n=285) and 26% placebo patients (n=174). Infusion-related reactions and hypersensitivity reactions that were grade =2 occurred more commonly among REGEN-COV patients (2% and 1% respectively) than placebo patients (1% and <0.5% respectively). The trial originally assessed a broader group of patients; however in late 2020 the trial was adjusted to exclude patients who were on mechanical ventilation or high-flow oxygen at baseline based on a potential safety signal identified by an Independent Data Monitoring Committee in 199 patients on mechanical ventilation or high flow-oxygen, a finding that was not replicated in the much larger RECOVERY trial that enrolled hospitalized patients with a broad range of severe COVID-19, including these patient groups. 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 both uninfected and infected asymptomatic household contacts of SARS-CoV-2 infected individuals; Treatment of non-hospitalized patients already infected with SARS-CoV-2; and to Treatment of certain patients hospitalized due to COVID-19 infection (as detailed in the IDWeek presentation), including the RECOVERY trial. Multiple analyses have shown that the antibody cocktail retains potency against the main variants of concern circulating within the U.S., including Delta (first identified in India), Gamma (first identified in Brazil), Beta (first identified in South Africa) and Mu (first identified in Colombia), with information available in the Fact Sheet for Healthcare Providers. 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. In the U.S., REGEN-COV is available for free to?eligible people, as part of a?U.S.?government funded program and earlier this month Regeneron announced a new agreement with the U.S. government to supply an additional 1.4 million 1,200 mg doses of REGEN-COV. Information on how to access REGEN-COV throughout the U.S. is available from the Department of Health and Human Services and the National Infusion Center Association. The development and manufacturing of REGEN-COV have been funded in part with federal funds from the Biomedical Advanced Research and Development Authority, part of the U.S. Department of Health and Human Services' Office of the Assistant Secretary for Preparedness and Response, under OT number: HHSO100201700020C.