Regeneron Halts Antibody Cocktail Treatment Trials in Seriously Ill COVID-19 Patients

Regeneron Pharmaceuticals, Inc. (Tarrytown, NY, USA) has paused the clinical study of its antibody cocktail drug to treat seriously-ill COVID-19 patients due to a potential safety concern.

The decision was based on a recommendation from the independent data monitoring committee (IDMC) for the REGN-COV2 antibody cocktail treatment trials for COVID-19 that the current hospitalized patient trial be modified. REGN-COV2 is a combination of two monoclonal antibodies (REGN10933 and REGN10987) and was designed specifically to block infectivity of SARS-CoV-2, the virus that causes COVID-19.


Based on a potential safety signal and an unfavorable risk/benefit profile at this time, the IDMC has recommended that further enrollment of patients requiring high-flow oxygen or mechanical ventilation should be placed on hold pending collection and analysis of further data on patients already enrolled. The IDMC has also recommended continuing enrollment of hospitalized patients requiring either no or low-flow oxygen as the risk/benefit remains acceptable in these cohorts. Finally, the IDMC has recommended continuation of the outpatient trial without modification.

Regeneron remains blinded to the data and has implemented the IDMC’s recommendations. The company has also informed the US Food and Drug Administration, which is currently evaluating REGN-COV2 for a potential Emergency Use Authorization in mild-to-moderate outpatients at high risk for poor outcomes. Regeneron has also shared the recommendation with the independent committee monitoring the RECOVERY trial in the UK, which is evaluating REGN-COV2 in hospitalized patients.

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