FDA Halts Use of Most Monoclonal Antibodies for COVID Treatment

The monoclonal antibody combinations bamlanivimab/etesevimab and casirivimab/imdevimab (REGEN-COV) should only be used for COVID-19 patients exposed to variants other than Omicron, the FDA said on Monday.

The agency revised the emergency use authorization (EUA) for the two antibody cocktails for use “only when the patient is likely to have been infected with or exposed to a variant that is susceptible to these treatments,” Patrizia Cavazzoni, MD, director of the FDA’s Center for Drug Evaluation and Research, said in the statement.

FDA cited “markedly reduced activity against the Omicron variant” as the reason for this revision. In addition, because CDC data indicate that over 99% of U.S. COVID cases are from Omicron, “it’s highly unlikely that COVID-19 patients … are infected with a variant other than Omicron, and these treatments are not authorized to be used at this time,” Cavazzoni added.

This action by the agency formalizes the recommendation made at the end of December by the NIH COVID Treatment Guidelines panel, which advised against the use of any monoclonal antibody treatment, with the exception of sotrovimab for high-risk COVID patients, as it was the only one with in vitro efficacy against Omicron.

FDA recommended sotrovimab and other non-monoclonal antibody therapies for outpatients at high risk of progressing to severe COVID, such as oral antiviral nirmatrelvir-ritonavir (Paxlovid), intravenous antiviral remdesivir (Veklury), and oral antiviral molnupiravir, which are “expected to work” against Omicron and are authorized for this high-risk patient population with mild to moderate COVID-19, according to Cavazzoni.

The agency noted that this action avoids exposing patients to side effects, some potentially serious, such as injection site reactions or allergic reactions from a treatment that “is not expected to provide benefit” against Omicron.