Regeneron Pharmaceuticals has reported that its experimental antibody cocktail, REGEN-COV, met the primary goal of the Phase II/III clinical trial in hospitalised adult Covid-19 patients.
REGEN-COV is a combination of the two monoclonal antibodies casirivimab and imdevimab that can hinder SARS-CoV-2 infectivity.
Subjects in the randomised, double-blind, placebo-controlled Phase II/III trial were randomised into a 1:1:1 ratio to receive a one-time infusion of 8,000mg or 2,400mg of REGEN-COV or placebo.
According to the trial data, REGEN-COV substantially decreased the viral load within seven days in subjects who were enrolled without having mounted their antibody response (seronegative) and needed low-flow or no supplemental oxygen.
The trial results also support the large RECOVERY trial in the UK in hospitalised patients, with numeric improvements reported across all clinical goals evaluated.
A 36% reduced risk of mortality was observed within 29 days of receiving the REGEN-COV treatment in the overall population while the risk declined by 56% in subjects who were seronegative at baseline.
In November 2020, the US Food and Drug Administration (FDA) granted Emergency Use Authorization (EUA) to the antibody cocktail to treat patients with mild to moderate Covid-19.
Indicated to treat certain adults and paediatric patients aged 12 years or above, the therapeutic can also be used in some post-exposure prophylaxis settings.
The FDA is currently reviewing the company’s request to add REGEN-COV for use in hospital settings to the EUA.
Regeneron president and chief scientific officer George Yancopoulos said: “These new results, combined with the nearly 10,000-patient RECOVERY trial, further validate how REGEN-COV can change the course of illness for patients even after they are hospitalised with Covid-19.
“It’s important to remember that while results from this and the RECOVERY trial indicate that patients unable to develop their own antibodies against Covid-19 historically had the poorest prognosis – and hence the greatest benefit from REGEN-COV treatment – both were largely conducted before widespread vaccination or the emergence of variants such as Delta.”