No more monoclonal antibody treatments for Covid are available in the United States: The Food and Drug Administration on Wednesday canceled its authorization of bebtelovimab, a drug previously given to patients who faced a high risk of serious illness.
Over the past two years, the FDA has cleared six monoclonal antibody treatments for Covid, but omicron’s many subvariants have made the drugs less effective, so the FDA has been gradually revoking each of those clearances. Bebtelovimab, made by Eli Lilly, was the last one standing.
According to the FDA announcement, the drug was “not intended to neutralize Omicron subvariants BQ.1 and BQ.1.1.”, which together now account for the majority of new infections recorded in the United States – approximately 62%, according to Centers for Spectacle disease control and prevention data.
“The big problem is that the monoclonal antibodies bind to a very small piece of the virus. As the virus changes, we are now in a position where we have lost them all because they no longer bind to the virus. virus,” said Dr. Arturo Casadevall, professor of medicine at Johns Hopkins School of Medicine.
Paxlovid has become the go-to treatment for most people at high risk of severe Covid, given that it continues to be effective against newer variants and is easy to administer (it’s a series of three pills taken twice a day for five days). Bebtelovimab, on the other hand, was an IV infusion that took about an hour.
But doctors often recommended the monoclonal antibody to people taking certain immunosuppressive drugs, such as cancer patients or transplant recipients, because Paxlovid can interact negatively with many of these drugs.
Dr. Rodney Rohde, chair of the clinical laboratory science program at Texas State University, said he was concerned about how immunocompromised patients would fare with fewer treatment options.
“There are still segments of the population that probably have very little protection,” he said. “You worry about this last surge of this virus this winter and going into the spring, if we see higher mortality or full hospital beds.”
In the spring, when the BA.2 omicron subvariant was dominant, research by Raymund Razonable, an infectious disease specialist at the Mayo Clinic in Minnesota, showed that bebtelovimab was as effective as Paxlovid in preventing serious illness in patients. High risk covid. But Razonable said his hospital switched to Paxlovid as the main treatment over the summer as new sub-variants began to spread.
About two months ago, he said, doctors started asking patients on bebtelovimab to report whether their symptoms hadn’t improved within a day or two. By the time the FDA revoked the treatment’s authorization, the Mayo Clinic had already stopped administering it, Razonable said, because doctors assumed it was no longer effective against BQ.1 and BQ.1.1.
Razonable said Mayo Clinic patients who are at high risk for severe Covid but cannot take Paxlovid are now being offered the antiviral drug remdesivir at the infusion center where the hospital previously gave monoclonal antibodies. But remdesivir infusions are given over three days, so patients need multiple appointments.
Another option for immunocompromised people is convalescent plasma, which is derived from donated blood from people who have already recovered from Covid. Casadevall said convalescent plasma is an effective alternative to monoclonal antibodies, but is more complicated to administer and monitor.
“It contains thousands of different antibodies, so convalescent plasma has a large magnitude that is not found in monoclonals,” he said.
However, pharmaceutical companies have not given up on the promise of new drugs based on monoclonal antibodies.
“We remain convinced that [monoclonal antibodies] play a vital role in the current fight against Covid-19, especially in those at high risk,” said a spokesperson for Vir Biotechnology, the company behind a monoclonal antibody called sotrovimab that was previously FDA cleared.
A spokesperson for Eli Lilly said the company is researching and evaluating candidate monoclonal antibodies. AstraZeneca, meanwhile, is developing a new antibody cocktail that it hopes to make available by the end of next year, a company spokesperson said.
The FDA cleared AstraZeneca’s monoclonal antibody drug Evusheld in December 2021 not as a treatment for Covid, but as a way to prevent infection in immunocompromised people who may not mount a strong antibody response to vaccines. But in October, the FDA announced that Evusheld might not be effective against circulating variants, and Razonable said his hospital was preparing for the upcoming revocation of its approval.
“Looking at the distribution of variants right now, Evusheld is efficient maybe about 30% of the time,” he said.
Casadevall said new monoclonal antibody drugs are always worth pursuing because they have been shown to be safe and effective against Covid.
“I wouldn’t give up on something like that,” he said. “I think it’s possible to find antibodies that will be active with the other variants.”