REGEN-COV Phase 3 Trial Meets Primary Outcome

Regeneron Pharmaceuticals, Inc. achieved positive results from the largest trial assessing any monoclonal antibody treatment in patients hospitalized with severe COVID-19. The UK RECOVERY trial found that adding investigational REGEN-COV (casirivimab and imdevimab) to usual care reduced the risk of death by 20% in patients who had not mounted a natural antibody response against SARS-CoV-2.

RECOVERY is the first trial large enough to definitively determine whether REGEN-COV reduces mortality in patients hospitalized with severe COVID-19. Previous Phase 3 trials in non-hospitalized COVID-19 patients have shown that REGEN-COV reduced viral levels, shortened the time to resolution of symptoms and significantly reduced the risk of hospitalization or death.

In a Phase 1/2 trial in hospitalized patients, REGEN-COV also rapidly reduced viral levels, with preliminary evidence suggesting that it lowered the risk of death or receiving mechanical ventilation, with the benefit driven by patients who entered the trial without having mounted a natural antibody response of their own (seronegative); and in the absence of REGEN-COV treatment, seronegative patients had higher mortality rates than patients who had already mounted their own immune response (seropositive).

The primary outcome of RECOVERY showed that adding REGEN-COV 8,000 mg to usual care reduced all-cause mortality by 20% in seronegative patients, compared to usual care alone (24% of patients in the REGEN-COV group died versus 30% in the usual care group by day 28).