FDA Links Tavneos to Dozens of Liver Injuries, Eight Deaths

The warning signs of serious liver failure from Tavneos can emerge in fewer than seven weeks. That is the median window, 46 days, that patients had been taking avacopan before developing drug-induced liver injury in the cases the Food and Drug Administration cataloged through October 9, 2024, and disclosed publicly on March 31.

The FDA identified 76 cases of drug-induced liver injury with a reasonable causal link to avacopan use through October 9, 2024. Of those, 74 produced serious outcomes, and eight patients died. Seven patients developed biopsy-confirmed vanishing bile duct syndrome, a condition involving progressive destruction of bile ducts that can impair bile flow and cause permanent liver damage. All seven required hospitalization, and three died. The FDA said the cases carried "reasonable evidence of a causal association" between avacopan and these outcomes, language regulators deploy with deliberate care.

The timing of this public communication matters precisely because Amgen is already contesting a separate FDA demand to pull the drug. On January 16, 2026, the FDA asked ChemoCentryx, the drug's original developer and now an Amgen subsidiary, to voluntarily withdraw Tavneos from the U.S. market. The company declined, saying it would continue engaging with regulators while maintaining that the drug's benefit-risk profile remained positive. By publishing the Drug Safety Communication, the agency escalated public pressure without invoking the compulsory withdrawal authority it holds but rarely uses.

Tavneos is one of Amgen's fastest-growing drugs, with sales growing 62 percent last year to reach $459 million. Amgen added the drug to its portfolio in 2022 when it acquired ChemoCentryx in a $3.7 billion deal, a year after the FDA approved Tavneos in October 2021 as an adjunctive treatment for adults with severe ANCA-associated vasculitis, a rare autoimmune disease in which the immune system attacks small blood vessels and can cause catastrophic organ damage including kidney failure.

While hepatotoxicity was previously documented in premarket studies and included in product labeling, the FDA said reports of VBDS and fatal cases represent newly identified risks. The geographic distribution of those reports also illuminates where post-market surveillance succeeded and where gaps remain: of the 76 cases, 66 were reported from Japan, followed by the United States with five, Europe with four, and Canada with one. Had international reporting pipelines not fed those cases into the FDA's review, the signal might have taken far longer to surface in U.S. data alone.

For patients currently taking Tavneos, the FDA specified a set of symptoms that should prompt immediate medical contact: unusual fatigue, nausea, vomiting, itching, light-colored stools, yellowing of the skin or eyes, dark urine, abdominal swelling, and pain in the upper right abdomen. Critically, the agency did not advise patients to stop the drug unilaterally. Discontinuing Tavneos without physician guidance could leave ANCA-associated vasculitis uncontrolled, a disease state that carries its own risk of fatal organ damage.

Robert Steinbrook, health research group director at the nonprofit watchdog Public Citizen, said the FDA's Drug Safety Communication was "important, but insufficient," arguing that if the agency had already requested a voluntary withdrawal in January 2026, the March safety alert raised the question of why the drug remained on the market at all. The European Medicines Agency's Committee for Medicinal Products for Human Use also initiated a review of avacopan around the same period, citing serious questions about amendments to data from the pivotal ADVOCATE study.

The Tavneos case is a case study in the structural limits of drug regulation: the fatal and irreversible injuries emerged from postmarketing reports filed years after approval, fed largely by clinicians in Japan, and accumulated quietly in adverse-event databases while the drug generated nearly half a billion dollars in annual revenue. The FDA can publish, warn, and request. When a company declines, the next step requires a legal fight the agency has shown historic reluctance to start.