The U.S. Food and Drug Administration has issued a stark new safety warning for Amgen’s rare disease drug Tavneos, linking it to 76 cases of serious liver injury, including a rare and often irreversible condition, and eight deaths. This action escalates a pre-existing regulatory conflict that began in January when the FDA first requested the drug’s voluntary withdrawal over data integrity concerns, a request Amgen refused. The development forces a urgent reckoning for patients with ANCA-associated vasculitis and highlights the high-stakes tension between drug access for rare diseases and post-market safety surveillance.
The U.S. Food and Drug Administration is urgently warning healthcare providers about severe liver injuries, including fatalities, connected to Amgen’s drug Tavneos, a treatment for a rare group of autoimmune diseases. The agency announced it has identified 76 cases of drug-induced liver injury with evidence suggesting a causal link to the medication. Among these, seven cases involved vanishing bile duct syndrome, a rare condition that can lead to permanent liver failure. Tragically, eight deaths were reported among the identified cases.
This safety alert represents a significant escalation in regulatory oversight for Tavneos (avacopan), which received FDA approval in 2021 for the treatment of anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis. This condition causes inflammation in small- to medium-sized blood vessels, primarily affecting the kidneys, lungs, and other organs. The FDA’s new guidance instructs physicians to closely monitor patients’ liver function and to discontinue Tavneos immediately if liver damage is suspected.
A Pre-Existing Crisis of Confidence: The January Data Integrity Challenge
This latest liver injury warning is not an isolated event but the second major regulatory blow for Tavneos in 2026. In January, the FDA formally requested that Amgen voluntarily withdraw the drug from the U.S. market. This extraordinary request stemmed from the agency’s re-evaluation of primary endpoint data for nine of the 331 patients enrolled in the pivotal late-stage clinical trial that supported the drug’s original approval. The FDA’s action signaled profound concerns about the foundational data underpinning the drug’s demonstrated efficacy and benefit-risk profile.
Amgen publicly declined the FDA’s withdrawal request at that time. The pharmaceutical giant stated it was not aware of any issues with the underlying patient data, maintained confidence in Tavneos’ overall benefit-risk profile, and confirmed it was engaged in ongoing discussions with the FDA regarding next steps. This standoff created a state of regulatory limbo, with the drug remaining on the market while its clinical trial data faced intense scrutiny.
Connecting the Dots: From Data Questions to Direct Patient Harm
The sequence of events reveals a two-front crisis for Tavneos. The first front, initiated in January, was a theoretical and procedural one concerning the integrity of the clinical trial data that proved the drug worked. The second front, now made public, is a concrete and tragic one involving direct, severe patient harm. The FDA’s identification of 76 liver injury cases, with a median time to onset of just 46 days after starting treatment, transforms the abstract concern about data into an immediate and tangible public health threat.
The agency’s statement that the U.S. prescribing information does not currently warn of vanishing bile duct syndrome, while labels in Europe and Australia do, further complicates the risk-benefit calculus for U.S. physicians and patients. This discrepancy suggests the full scope of the drug’s rare but serious toxicity profile may have been under-communicated in the United States prior to this latest analysis.
Global Regulatory Pressure Mounts
The FDA’s actions are part of a broader international reassessment of Tavneos. Following the FDA’s January concerns, the European Medicines Agency (EMA) initiated its own formal review of the drug. The EMA stated its review was launched “following emerging information that raises questions regarding the data integrity (of its study).” This synchronized scrutiny across the world’s two primary drug regulatory agencies underscores the seriousness of the issues surrounding Tavneos’ approval and post-market performance.
- January 2026: FDA requests Amgen voluntarily withdraw Tavneos over data integrity concerns in the pivotal trial; Amgen refuses.
- January 2026: European Medicines Agency opens a formal review of Tavneos citing data integrity questions.
- March 31, 2026: FDA issues a new safety warning detailing 76 cases of liver injury, 7 of vanishing bile duct syndrome, and 8 deaths linked to the drug.
The Stakes for Patients and the Future of a Drug Class
For the approximately 3,000 to 4,000 Americans diagnosed annually with ANCA-associated vasculitis, Tavneos represented a long-awaited oral alternative to lifelong, high-dose corticosteroid therapy. Its approval was hailed as a major advance. The current situation now forces patients and their doctors into an impossible position: weighing the known risks of a life-threatening liver injury against the known risks of their underlying autoimmune disease and the side effects of older treatments.
For Amgen, the implications are severe. Tavneos was a cornerstone of the company’s rare disease portfolio and a product with blockbuster potential. The dual crises of a challenged approval and a fatal safety signal threaten not only current revenue but also the company’s reputation for clinical trial rigor and its pipeline of future therapies. The company’s statement that it was not immediately available for comment on the FDA’s latest warning speaks to the gravity of the situation.
Why This Matters Beyond a Single Drug
The Tavneos situation is a critical case study in the modern drug safety ecosystem. It illustrates the intense pressure on regulatory agencies to rigorously police not just pre-approval trials but also the real-world data that emerges after a drug reaches patients, especially for drugs treating small populations where large-scale safety signals are harder to detect early. The timeline—from a data integrity query to a fatality-linked safety warning in under three months—shows how quickly a drug’s status can unravel.
It also highlights the profound ethical dilemma when a drug for a serious, rare condition shows both a potential efficacy signal and a serious, potentially fatal toxicity. The public and medical community will be watching to see if the FDA escalates its regulatory actions, potentially moving from a warning to mandatory label changes or even a suspension of sales. The outcome will set a precedent for how aggressively the agency acts when post-marketing evidence of harm converges with questions about the original proof of benefit.
For now, the message from the FDA is unequivocal: Tavneos carries a risk of severe, rapid-onset liver damage that can be fatal. Healthcare providers must be vigilant, and patients must be informed. The definitive source for the FDA’s safety communication and the underlying case data is the agency’s own announcement, which was first reported by Reuters.
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