Regeneron says its coronavirus antibody cocktail loses potency against omicron

Regeneron Pharmaceuticals, the maker of a popular monoclonal antibody cocktail used as a treatment for many coronavirus patients who have not been vaccinated, announced Thursday that its covid-19 therapy loses potency against the omicron variant.

The company, which warned earlier this month that its antibody treatment may not be as effective against the new variant, said data confirms it has “diminished potency” against omicron but remains useful against delta.

“While Regeneron’s currently authorized REGEN-COV antibodies have diminished potency against Omicron, they are active against Delta, which currently is the most prevalent variant in the U.S.,” the company said in a news release.

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The antibody treatment, a cocktail of the monoclonal antibodies casirivimab and imdevimab, is designed to prevent infected people from developing severe illness.

Leonard Schleifer, Regeneron’s CEO, told CNBC that the company’s next-generation drugs being developed were more likely to work against omicron — and could be available next year.

“We’ve got new antibodies now that we’ve tested, and they work against both delta and omicron,” he said, describing omicron as “a pretty scary mutation.” “We hope to get in the clinic very early next year with those. We’re going to work with the FDA.”

Regeneron’s announcement comes as omicron, which is thought to be much more contagious if potentially less severe than its predecessors, is surging around the world. In the United States, where the overall death toll from the pandemic surpassed 800,000 this week, federal health officials warned there could be a massive wave of infections by January.

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Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, stressed Wednesday that an omicron-specific vaccine is not needed right now, as early data indicates that existing booster shots bolster disease-fighting antibodies.

But there is concern for those who remain unvaccinated and have leaned on Regeneron or other similar cocktails as a coronavirus preventive or treatment if they are infected.

“I am hopeful that maybe this will nudge people who haven’t gotten the vaccine to get vaccinated,” Rupali J. Limaye, a behavioral and social scientist at Johns Hopkins University who specializes in vaccination issues, told The Washington Post. “At the same time, I’m a little worried about what we’re going to see in terms of hospital beds in January.”

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There have been more than 120,000 new coronavirus cases a day over the last week in the United States, according to data tracked by The Washington Post. More than 69,000 people are currently hospitalized for the virus, a figure that has increased since last week.

As the variant is spreading in South Africa and European countries, recent laboratory studies indicate that these coronavirus cases will severely diminish monoclonal antibodies. More evidence has suggested that monoclonal antibodies, which block the virus by recognizing the distinctive spikes on its surface, will struggle to recognize and stop omicron’s heavily mutated spikes.

Regeneron, whose monoclonal antibody cocktail has found conservative support from the likes of former president Donald Trump and Florida Gov. Ron DeSantis (R), acknowledged last month that its treatment could be less effective against the new variant. A preprint study published last week showed how omicron could evade the cocktails from Regeneron, Eli Lilly and AstraZeneca, which recently received authorization for a monoclonal treatment to prevent covid-19 in people whose immune systems do not respond to vaccines.

Monoclonal antibody treatments are effective and free to high-risk coronavirus patients, but experts say the treatment alone cannot prevent the next surge. (Julie Yoon/The Washington Post)

With Regeneron’s treatment not being as potent against omicron, there is added pressure, and urgency, on Pfizer and Merck to develop anti-viral pills to help combat the virus’s ability to make copies of itself. While the drugs show promise, both might have limitations.

On Thursday, Schleifer stressed to CNBC that everyone should get vaccinated, and people might need “more than one preventive” against the virus. The Regeneron CEO described the difference in multiple mutations from delta to omicron as “a giant leap.”

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He reiterated that Regeneron planned to conduct trials on the new antibodies during the first quarter of 2022.

“I think we need to figure out a way that we can get this to patients on a large scale before the next variant shows up,” he said in the TV interview. “We just don’t want to be chasing our tail here.”

Limaye told The Post that she wonders what the upcoming holiday could look like for unvaccinated Americans spending Christmas together in indoor, maskless groups now that Regeneron has said that its cocktail is not as potent against omicron.

“This is going to be a real challenge because there is a gap in antibody products,” she said. “If that cocktail’s effectiveness is taken away, how does that change people’s perspectives on the vaccine?”

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Schleifer, who called for “a whole new regulatory schema” to address rapidly-mutating infectious diseases, emphasized that antibody treatments, such as Regeneron’s, that show effectiveness against omicron could help reduce hospitalizations in the coming months.

“It’s possible that delta will surge, the flu surge, and so will omicron,” Schleifer said to CNBC. “So we’re going to need a full tool kit here.”

He also called for people to keep practicing preventive measures, such as masking and social distancing, while Regeneron tests its next-generation drugs to combat omicron.

“There are measures that we can take right now that can help us,” he said. “But we do have to go faster and figure this out.”

Carolyn Y. Johnson contributed to this report.