The US drugs regulator has rescinded its authorisation for the monoclonal antibody treatments made by Eli Lilly and Regeneron, which proved highly effective at fighting earlier strains of Covid-19 but do not work well against the Omicron variant.
The Food and Drug Administration announced on Monday it was removing its emergency authorisation for doctors to prescribe the treatments, which work by infusing patients with proteins that mimic the body’s immune response.
Patrizia Cavazzoni, director of the FDA’s Center for Drug Evaluation and Research, said in a statement: “Because data show these treatments are highly unlikely to be active against the Omicron variant, which is circulating at a very high frequency throughout the United States, these treatments are not authorised for use in any US states, territories, and jurisdictions at this time.”
The FDA said it could authorise the treatments again if they were proven to be effective against Covid-19 variants circulating in particular regions.
The treatment made by Regeneron was credited with helping then-president Donald Trump recover quickly from the virus when he was infected in 2020. But federal agencies have discouraged their use as Omicron has become the dominant strain in the US, saying it is not worth exposing patients to the potential side-effects.
That has triggered a dispute with Ron DeSantis, the Republican governor of Florida, who has accused Joe Biden’s administration of “playing games” with the therapies by restricting their supply.
Critics of the governor have recently questioned the practice of continuing to provide the treatments for Covid, which have lost their effectiveness against the Omicron variant, according to studies.
Christian Ramers, an infectious disease specialist at the Family Health Centers of San Diego, which previously offered Eli Lilly and Regeneron monoclonal antibodies, said it was not ethical to continue providing them.
“It’s really a shame that that’s happening in some places,” said Ramers. “It was pretty clear that the Regeneron and Eli Lilly product have almost no activity even at very high concentrations against Omicron. This was realised quite early with some . . . studies.”
Health experts said the declining effectiveness of the two most commonly used antibody treatments has led to shortages of a third monoclonal antibody treatment sotrovimab, which is made by GlaxoSmithKline and Vir Biotechnology and has shown activity against Omicron.
However, antiviral drugs developed by Pfizer and Merck are beginning to be provided by health clinics following their recent authorisation by the FDA.
Eli Lilly said it had agreed with the FDA that it was not medically appropriate at this time to treat patients suffering from mild to moderate Covid cases with its monoclonal antibody, as it was not effective at treating Omicron.
“Authorisation status will change as needed, depending on prevalence and trends of variants of concern,” it said.
Eli Lilly said it was working urgently with the FDA to demonstrate that a different antibody therapy was effective against all variants of concern, including Omicron.
Regeneron did not immediately respond to a request for comment.
