Regeneron’s Antibody Combination Therapy Reduces COVID-19 Mortality Risk

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RECOVERY trial results have shown that Regeneron’s investigational antibody combination therapy reduces the mortality risk for seronegative hospitalized patients with severe COVID-19.

Results of the Randomized Evaluation of COVID-19 Therapy (RECOVERY) trial have shown that Regeneron’s investigational antibody combination therapy reduces the mortality risk for hospitalized patients with severe COVID-19 whose immune response has not started naturally. The trial results were released in a June 16, 2021 press release.

Regeneron’s combination therapy comprises two monoclonal antibodies—casirivimab and imdevimab—which specifically bind to two different sites on the coronavirus spike protein. In previous studies on non-hospitalized patients, the therapy was shown to reduce viral load, shorten the time to resolution of symptoms, and significantly reduce the risk of hospitalization or death.

Preliminary results of a small trial of hospitalized patients suggested that the combination therapy would provide a clinical benefit to hospitalized patients who had not mounted a natural immune response (seronegative). The RECOVERY trial included 9785 patients who were hospitalized with COVID-19, which is a sufficiently large patient population to determine whether the treatment reduces mortality.

Of the patients included in the trial, approximately one-third were seronegative at baseline. For these patients, the combination therapy was found to significantly reduce the primary outcome of 28-day mortality. This result was not comparable with patients who were seropositive at baseline.


“These results are very exciting. The hope was that, by giving a combination of antibodies targeting the SARS-CoV-2 virus, we would be able to reduce the worst manifestations of COVID-19. There was, however, great uncertainty about the value of antiviral therapies in late-stage COVID-19 disease,” said Sir Peter Horby, professor of Emerging Infectious Diseases in the Nuffield Department of Medicine, University of Oxford, and joint chief investigator for the RECOVERY trial, in the press release. “It is wonderful to learn that even in advanced COVID-19 disease, targeting the virus can reduce mortality in patients who have failed to mount an antibody response of their own.”

“We now know that this antibody combination is not only bad for the virus, but it is also good for the sickest patients who have failed to mount a natural immune response of their own,” added Sir Martin Landray, professor of Medicine and Epidemiology at the Nuffield Department of Population Health, University of Oxford, and joint chief investigator, in the press release. “That is excellent news—it is the first time that any antiviral treatment has been shown to save lives in hospitalized COVID-19 patients. We are incredibly grateful to the many NHS staff and patients who have contributed to today’s discovery.”

Source: University of Oxford