In an April letter to Amgen, which owns the drug, the agency cited reports of serious, sometimes fatal liver injury and argued that Tavneos no longer has "substantial evidence" that it works.
The FDA alleges that employees of ChemoCentryx, the company that ran the pivotal trial before Amgen acquired it, manipulated the data.
According to the agency, they reassessed the remission status of a handpicked group of patients after unblinding the trial, and they did not tell the FDA about the original results or the reassessment.
Tavneos was approved in October 2021 after a narrow advisory committee vote, despite reservations about the trial's design, and sales reached nearly half a billion dollars in fiscal year 2025.
Amgen bought ChemoCentryx for nearly $4 billion a year after approval.
The FDA says the drug has been linked to eight deaths and dozens of hospitalizations.
It also says that without a firm response, other companies would have an incentive to act deceptively.
Tracy Beth Høeg, acting director of the FDA's drug center, said the drug was approved only because the data were manipulated.
Walter Kraft, a committee member who voted for approval, said the trial system rests on trust.
Outside the US, the New England Journal of Medicine retracted the trial paper, and the European Union has taken Tavneos off the market.
The United Kingdom has announced it will do the same.
Withdrawal in the US is not automatic. The law requires the FDA to give notice and offer the manufacturer a chance at a public hearing, which is held only if the company shows a genuine factual dispute. Amgen could sue if the agency then withdraws approval. In a 104-page submission, Amgen said the reassessment did not match its own approach and that ChemoCentryx should have disclosed it. It maintained that no underlying data were changed and that the review corrected a small number of errors. The company cites an independent Duke Clinical Research Institute reanalysis, in which Tavneos recipients fared no worse on remission, and real-world data suggesting it reduces steroid use. Some patients, including Chloe Cusano, who credits it with helping her taper off steroids, want it to stay available. Eric Roberts of the University of California, San Francisco, says his registry study found low rates of liver injury. Joshua Skydel of Yale argues that several of Amgen's cited studies are unpublished and that the company has fallen behind on required post-marketing studies. A court hearing on a proposed $69 million settlement of the related investor lawsuit is expected on October 29.
