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 In April of this year, the FDA issued a letter proposing that Tavneos be withdrawn from the US market, citing reports of serious, sometimes fatal, liver injury, and arguing that the drug now lacks “substantial evidence” that it works.
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