The FDA has determined that the monoclonal antibody pemivibart (Pemgarda) is likely to be effective against currently circulating SARS-CoV-2 variants, including KP.3.1.1 and LB.1.
“Based on current CDC Nowcast estimates and variant spike receptor binding domain similarity to tested variants, FDA anticipates Pemgarda will retain activity against the currently circulating variants in the U.S.,” the agency said in a press release.
This is welcome news for patients at risk for severe COVID-19, such as those with immunocompromising conditions. Pemivibart remains the only available monoclonal antibody for the prevention of COVID-19 in this population.
In late August, the FDA had revised the emergency use authorization (EUA) for pemivibart, adding a limitation of authorized use over concerns that KP.3.1.1 may have had substantially reduced susceptibility to the drug. The FDA indicated that pemivibart should only be used for pre-exposure prophylaxis of COVID-19 in immunocompromised patients when the combined national frequency of SARS-CoV-2 variants with substantially reduced susceptibility to the drug is less than or equal to 90%.
However, in the several days following that EUA revision, drugmaker Invivyd announced that in vitro testing showed pemivibart has neutralization activity against the variants in question. The company submitted the data to the FDA.
On Thursday, the agency issued a revised fact sheet for healthcare providers that now includes updated pemivibart neutralization EC50 values for currently and recently circulating SARS-CoV-2 variants.
As of September 14, the most frequently reported SARS-CoV-2 variant in the U.S. is KP.3.1.1, followed by KP.2.3, LB.1, and KP.3. The latest CDC Nowcast estimates that KP.3.1.1 comprises about 53% of circulating variants.
“KP.3.1.1 and LB.1 exhibit EC50 values that are 3.2- to 2.4-fold higher than that of JN.1, respectively, indicating that pemivibart is likely to retain adequate neutralization activity against KP.3.1.1 and LB.1,” the FDA wrote in a memo. “KP.2.3 and other untested variants are likely to exhibit similar susceptibilities to pemivibart.”
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