FDA Proposes Pulling Amgen Rare Disease Drug from Market

Rare Daily Staff

The U.S. Food and Drug Administration has taken the unusual step of proposing to withdraw Amgen’s vasculitis drug Tavneos from the market, saying new evidence undercuts the medicine’s efficacy and reveals that key clinical data used to secure its 2021 approval were manipulated and not fully disclosed to the agency.

The FDA’s Center for Drug Evaluation and Research said it has proposed withdrawing Tavneos after determining that new information shows the drug has not been demonstrated to be effective for its approved use in adults with severe, active ANCA-associated vasculitis when used alongside glucocorticoids and other standard-of-care therapies.

Tavneos, first cleared on Oct. 7, 2021, was approved as an adjunctive treatment for granulomatosis with polyangiitis and microscopic polyangiitis, two rare, life-threatening forms of small- to medium-vessel vasculitis.

According to the agency, CDER’s proposal will be published in the Federal Register and accompanied by a public docket where supporting materials will be posted and public comments accepted as part of the formal process. For now, the drug remains available while regulators move through procedural steps and weigh the sponsor’s response.

In a notice of opportunity for a hearing sent to ChemoCentryx, now a wholly owned Amgen subsidiary, CDER said it learned—more than three years after approval—that unblinded study personnel had manipulated results from the pivotal Phase 3 trial so the drug appeared effective, even though the original analysis did not support that conclusion.

The agency further alleges that the applicant failed to share the original analysis with the FDA, in violation of regulatory requirements, and instead provided analyses based on manipulated data that formed the basis of approval.

These revelations led CDER to conclude it can no longer rely on the pivotal data package and “can no longer conclude that there is, or has ever been, a valid demonstration that Tavneos is effective” for the approved indication. On that basis, CDER is proposing withdrawal under statutory provisions that allow the agency to rescind approval when substantial evidence of effectiveness is lacking or when approval was based on untrue statements of material fact.

In addition to the integrity and efficacy concerns, CDER said it is “increasingly concerned” about Tavneos’ safety profile, pointing to postmarketing cases of serious drug-induced liver injury, including fatal events. In a March 31, 2026, drug safety communication, the agency highlighted reports of vanishing bile duct syndrome, a rare and severe form of cholestatic liver injury marked by progressive destruction and loss of intrahepatic bile ducts.

The FDA said it had identified 76 postmarketing cases of serious liver injury in patients taking avacopan, including seven biopsy-confirmed cases of vanishing bile duct syndrome, three of which were fatal. The median time from starting avacopan to DILI onset in those cases was 46 days, and all affected patients required hospitalization. While hepatotoxicity was already listed as a serious adverse reaction in Tavneos labeling based on premarket data, the identification of vanishing bile duct syndrome and fatal DILI has been framed as a new and more alarming safety signal.

Amgen can request a hearing before the FDA commissioner to contest CDER’s proposal and present its position on continued marketing of Tavneos. If the company requests a hearing, the commissioner will decide whether to grant it, preside over any public proceeding, and ultimately determine whether to formally withdraw the drug’s approval.

Tavneos will remain on the U.S. market unless Amgen voluntarily removes it or the commissioner orders withdrawal at the end of the process.

In the meantime, the agency is urging clinicians to reassess use of Tavneos in their patients with ANCA-associated vasculitis in light of both the efficacy questions and the evolving liver safety profile. The agency recommends that health care professionals discuss Tavneos and alternative treatment options with patients to decide whether to start or continue the drug while its marketing status is under review.