- "Our cocktail, certainly one of the antibodies should take a hit, the other one, maybe less," Regeneron CEO Leonard Schleifer told CNBC's "Squawk Box" on Tuesday.
- Schleifer said the antibody cocktail remains very effective against delta, the predominant variant in the U.S.
- He said that Regeneron has started a clinical trial on an antibody that looks promising.
Regeneron Pharmaceuticals CEO Leonard Schleifer on Tuesday said the company's Covid-19 treatment may be less effective against the heavily mutated omicron variant of the virus.
Regeneron's Covid treatment is a cocktail of two monoclonal antibodies administered in a hospital or clinic intravenously to treat patients at risk of developing a severe case of the disease. The Food and Drug Administration approved it for emergency use last year.
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"Our cocktail, certainly one of the antibodies, should take a hit, the other one, maybe less," Schleifer told CNBC's "Squawk Box" on Tuesday. "We started with very potent antibodies, so we have to look at how much the hit is, but more importantly, we have to get ready for the next one," he said.
Regeneron, in a statement earlier Tuesday, said the mutations present in the omicron variant "indicate that there may be reduced neutralization activity of both vaccine-induced and monoclonal antibody-conveyed immunity," including the company's antibody cocktail.
The company pointed out, however, that there isn't yet any data directly testing the impact of omicron on vaccines and monoclonal antibodies.
Schleifer said the antibody cocktail remains very effective against delta, the predominant variant in the U.S. He said Regeneron has started a clinical trial on an antibody that looks promising.
"Just like vaccines are going to have to adapt, we're probably going to constantly have to adapt our monoclonals and we have a large repertoire of them, and then we're going to have to keep cycling them," Schleifer said.
The omicron variant of the virus that causes Covid-19 has more than 30 mutations to the spike protein, which is the mechanism the virus uses to bind to human cells. Some of the mutations are associated with higher transmission and lower antibody protection, according to the World Health Organization.
While omicron is believed to be more infectious than past variants, its exact impact on the strength of vaccines is unclear. Pfizer CEO Albert Bourla told CNBC on Monday that vaccines could be less effective against omicron, but more data is needed.
The WHO and scientists have also said it could take weeks to understand whether omicron is likely to cause severe illness or escape protection against immunity induced by vaccines.
Vaccine makers are already preparing for a situation where their current shots are less effective against the new variant, with several companies announcing Monday that they had begun work on vaccines tailored for omicron.
— Reuters contributed to this report.
Correction: Regeneron's statement was Tuesday. An earlier version misstated the day.