// ARS TECHNICA — SALUTE
The FDA wants to pull its approval of a drug. It’s not so easy.
The regulator says Tavneos was approved on the basis of manipulated study data. Should patients still have access to it?
In May 2021, the US Food and Drug Administration released a lengthy briefing document on an experimental medication for a rare autoimmune form of vasculitis that often damages the kidneys and lungs. The agency was on the fence about whether to approve the treatment, and it wanted an independent advisory committee to weigh in. Among the questions at hand: Was the drug meaningfully better than existing therapies?
Participants in the study, which had been conducted by the California biotechnology company ChemoCentryx, did appear to have slightly higher rates of symptom remission after one year. But according to the FDA, it was hard to interpret the results because the study’s design had been less than optimal. Some advisory committee members expressed a similar view. The effect of the drug, said one, “is just not well verified by this study.”
At the same time, many patients, and some physicians, saw in the data a potentially helpful medication, one that might lessen patients’ reliance on steroids, which are highly effective but often cause severe side effects.
The advisory committee ultimately voted narrowly to recommend approval, and the FDA followed that advice, greenlighting the drug on October 7, 2021. The drug, marketed as Tavneos, started making its way into clinics. A year after approval, ChemoCentryx was acquired by Amgen, one of the world’s largest pharmaceutical companies. The cost, even today, isn’t minor: $220,000 per year, according to Drugs.com. In fiscal year 2025, sales of Tavneos reached nearly half a billion dollars.
This financial windfall has unfolded despite a long-roiling investor lawsuit—one that incidentally uncovered what the FDA today believes is evidence that ChemoCentryx employees manipulated the data in the pivotal trial submitted to the agency. In April of this year, the FDA issued a letter proposing that Tavneos be withdrawn from the US market, citing reports of serious, sometimes fatal, liver injury, and arguing that the drug now lacks “substantial evidence” that it works.
These revelations have triggered a dramatic cascade of events. This summer, the New England Journal of Medicine retracted a paper describing the clinical trial and Tavneos was taken off the market in the European Union. The United Kingdom has announced that it, too, will remove the product from the market. And on October 29, a court hearing is expected to proceed over Zoom to consider a proposed $69 million settlement for the lawsuit.
But the fate of Tavneos, at least in the United States, is far from sealed. Amgen has pushed back against its critics, insisting that—whatever the details of ChemoCentryx’s data handling—its drug works as advertised and should stay on the market. In July, the company submitted a 104-page document to the FDA stating that “the totality of the evidence supports the continued availability of TAVNEOS.”
Some patients and academic experts also believe the drug is an important treatment option. “This appears to be an efficacious medication,” said Eric Roberts, an epidemiologist at the University of California, San Francisco, who co-authored an independent registry study of Tavneos.
The dispute is emblematic of the FDA’s longstanding struggle to regulate drugs of uncertain efficacy, said Reshma Ramachandran, a physician and co-director of the Yale Collaboration for Regulatory Rigor, Integrity, and Transparency. Absent more rigorous studies, either before or after a drug goes on the market, Ramachandran worries, “we’re just going to be living in uncertainty in terms of whether or not these drugs actually work.”