US FDA grants EUA to monoclonal antibodies from Regeneron for COVID-19 treatment

The US Food and Drug Administration has issued an emergency use authorisation (EUA) for casirivimab and imdevimab to be administered together for the treatment of mild to moderate COVID-19 in adults and paediatric patients (12 years of age or older weighing at least 40 kilograms [about 88 pounds]) with positive results of direct SARS-CoV-2 viral  testing and who are at high risk for progressing to severe COVID-19. This includes those who are 65 years of age or older or who have certain chronic medical conditions.

In a clinical trial of patients with COVID-19, casirivimab and imdevimab, administered together, were shown to reduce COVID-19-related hospitalisation or emergency room visits in patients at high risk for disease progression within 28 days after treatment when compared to placebo. The safety and effectiveness of this investigational therapy for use in the treatment of COVID-19 continues to be evaluated.

Casirivimab and imdevimab must be administered together by intravenous (IV) infusion.

Casirivimab and imdevimab are not authorised for patients who are hospitalised due to COVID-19 or require oxygen therapy due to COVID-19. A benefit of casirivimab and imdevimab treatment has not been shown in patients hospitalised due to COVID-19. Monoclonal antibodies, such as casirivimab and imdevimab, may be associated with worse clinical outcomes when administered to hospitalised patients with COVID-19 requiring high flow oxygen or mechanical ventilation.

Casirivimab and imdevimab are monoclonal antibodies that are specifically directed against the spike protein of SARS-CoV-2, designed to block the virus’ attachment and entry into human cells.

The data supporting this EUA for casirivimab and imdevimab are based on a randomised, double-blind, placebo-controlled clinical trial in 799 non-hospitalised adults with mild to moderate COVID-19 symptoms. Of these patients, 266 received a single intravenous infusion of 2,400 milligrams casirivimab and imdevimab (1,200 mg of each), 267 received 8,000 mg casirivimab and imdevimab (4,000 mg of each), and 266 received a placebo, within three days of obtaining a positive SARS-CoV-2 viral test.

The prespecified primary endpoint for the trial was time-weighted average change in viral load from baseline. Viral load reduction in patients treated with casirivimab and imdevimab was larger than in patients treated with placebo at day seven. However, the most important evidence that casirivimab and imdevimab administered together may be effective came from the predefined secondary endpoint of medically attended visits related to COVID-19, particularly hospitalisations and emergency room visits within 28 days after treatment. For patients at high risk for disease progression, hospitalisations and emergency room visits occurred in three per cent of casirivimab and imdevimab-treated patients on average compared to nine per cent in placebo-treated patients. The effects on viral load, reduction in hospitalisations and ER visits were similar in patients receiving either of the two casirivimab and imdevimab doses.

The EUA was issued to Regeneron Pharmaceuticals.