The Food and Drug Administration has proposed withdrawing Tavneos (avacopan), a costly treatment for a rare autoimmune vasculitis, after concluding that the California biotech that developed it manipulated pivotal-trial results and that the drug now lacks substantial evidence of effectiveness, Ars Technica reported, reprinting an Undark investigation¹.

The agency approved the drug on Oct. 7, 2021, after an independent advisory committee voted narrowly in favor despite FDA briefing documents that questioned whether ChemoCentryx's study showed a meaningful benefit over existing care¹. Tavneos was intended to reduce long-term steroid use in ANCA-associated vasculitis, a condition that can damage kidneys and lungs¹. Amgen bought ChemoCentryx for nearly $4 billion a year after approval; list price is about $220,000 a year, and fiscal 2025 sales approached $500 million, the report said¹.

A shareholder lawsuit later produced a report that, according to the FDA as described by Undark, showed ChemoCentryx's original analysis did not find better one-year remission on the drug¹. After unblinding, employees selected some patients for re-adjudication of remission status, which the agency says violated the protocol and cherry-picked outcomes needed for approval, and the company did not disclose the original results or the reassessment¹.

In April, FDA sent Amgen a letter proposing withdrawal, citing serious, sometimes fatal liver injury and arguing the drug lacks substantial evidence that it works¹. Acting CDER director Tracy Beth Høeg told Undark the company "swindled billions of dollars" by gaining approval through manipulated data and that the product has been linked to eight deaths and dozens of hospitalizations¹. The New England Journal of Medicine later retracted the trial paper at the request of two academic authors; the European Union took Tavneos off the market and the United Kingdom announced it would do the same¹. A Zoom hearing on a proposed $69 million investor settlement was expected Oct. 29¹.

Amgen has submitted a 104-page response saying the totality of evidence supports keeping Tavneos available¹. The company said ChemoCentryx's 2019 re-adjudication "followed a prespecified procedure" and that "No clinical data were altered," and that it had not known of the undisclosed steps¹. It cites a Duke Clinical Research Institute re-adjudication that did not meet FDA's one-year remission bar but found patients on the drug fared no worse, plus unpublished real-world data on steroid reduction¹.

Some clinicians and patients still want access¹. UCSF epidemiologist Eric Roberts, co-author of an independent registry study, said the medicine appears efficacious and that U.S. liver-injury rates were low with monitoring¹. A patient quoted in the piece credited the drug with helping her taper steroids¹. Yale rheumatology fellow Joshua Skydel said the product should not remain on the market given questioned trial data and unpublished supporting studies, and that Amgen has missed post-marketing study deadlines the FDA requested at approval¹.

Withdrawing an approved drug requires notice, a chance for a hearing if facts are disputed, and can be followed by a lawsuit, Ohio State law professor Patricia Zettler told Undark¹. Høeg said she doubts real-world data will meet FDA's bar, noting EU and UK findings¹. The April letter said withdrawal is needed to protect public health and the integrity of approvals¹. The U.S. outcome remains unresolved¹.

Not medical advice.

Sources

1. Ars TechnicaThe FDA wants to pull its approval of a drug. It’s not so easy.7:04 AM

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