Casirivimab, Imdevimab Combination Therapy Significantly Reduces Viral Load in Hospitalized Patients With COVID-19


Seronegative patients with COVID-19 who required low-flow or no supplemental oxygen receiving Ronapreve had significant reductions in viral load within 7 days of treatment.

Seronegative patients with COVID-19 who required low-flow or no supplemental oxygen receiving a combination therapy of casirivimab and imdevimab (Ronapreve, Roche) had significant reductions in viral load within 7 days of treatment, according to data from the phase 2/3 REGN-COV 2066 study. This study also reported clinical results that support those of the larger UK RECOVERY trial, which demonstrated that patients receiving Ronapreve in addition to standard-of-care treatment had quantifiable improvements across all assessed clinical endpoints.

“COVID-19 continues to devastate communities with over 4.7 million recorded deaths worldwide, the majority of which were in hospitalized patients. While vaccines are effective in preventing hospitalizations, a significant unmet need remains in many who still get infected, and whose disease requires hospital care,” said Levi Garraway, MD, PhD, chief medical officer and head of global product development at Roche, in a press release. “These data add to previous findings that support the potential of Ronapreve in hospitalized patients, which may also help to ease pressure on health care systems.”

Ronapreve, a combination of 2 monoclonal antibodies, is designed to block the infectivity of SARS-CoV-2. This combination therapy is believed to bind non-competitively to the critical receptor binding domain of the virus's spike protein, which the investigators hypothesized would diminish the ability of mutant viruses to escape treatment.

The REGN-COV 2066 study was a randomized, double-blind, placebo-controlled trial evaluating the use of Ronapreve in 1197 hospitalized adult patients with COVID-19. Among study participants, 530 were receiving no supplemental oxygen when entering the trial and 667 were receiving low-flow oxygen. Patients were randomized 1:1:1 to receive a 1-time infusion of either 8000 mg of Ronapreve, 2400 mg of Ronapreve, or placebo. No serious or dose-dependent safety signals were observed in patients treated with Ronapreve.

Patients in the efficacy analysis of the REGN-COV 2066 study had experienced symptoms for an average of 6 days prior to entering the trial, and 43% were seronegative. The average age of patients was 62 years, 54% were male and 46% were female. Approximately 30% of trial participants were Hispanic and 12% were African American.


Phase II/III trial shows Ronapreve™ (casirivimab and imdevimab) significantly reduces viral load within seven days of treatment in patients hospitalised with COVID-19 [news release]. Roche; September 30, 2021. Accessed September 30, 2021.

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