Kissei Urges Caution on Tavneos After 20 Deaths Reported in Japan
Japanese partner Kissei has warned doctors not to prescribe Tavneos to new patients following reports of 20 fatalities and serious liver injuries linked to the drug. The move adds to regulatory scrutiny of the therapy that treats rare autoimmune vasculitis and follows recent actions by international regulators. (medicalxpress.com)
Kissei issues safety notice citing 20 fatal cases
Kissei Pharmaceutical sent a notice to healthcare professionals on May 15, 2026, saying that 20 fatal cases have been reported among patients treated with Tavneos since its launch in Japan in June 2022. The notice warned of a risk of “severe liver dysfunction” and advised clinicians to refrain from initiating the treatment in new patients while reviewing ongoing therapy for current recipients. (medicalxpress.com)
Kissei said Tavneos has been prescribed to roughly 8,500 patients in Japan since approval, and the company is collecting more safety data to better characterise the reported events. The advisory has prompted hospitals and physicians to reassess monitoring schedules and risk–benefit judgments for patients with ANCA-associated vasculitis. (ad-hoc-news.de)
Amgen responds, says no confirmed US deaths
Amgen, which holds rights to Tavneos in the United States, issued a statement saying media reports about the fatalities were based on a regulatory notification and lacked broader context. Amgen noted that in the U.S. more than 8,000 patients have been treated with Tavneos and that there have been no known deaths in the country linked to severe liver injury. (amgen.com)
The company reiterated its view that Tavneos provides an important treatment option for patients with severe ANCA-associated vasculitis and said it continues to engage with regulators and clinicians while reviewing global safety data. Amgen also pointed to existing product labelling that includes hepatotoxicity warnings and liver-monitoring guidance. (amgen.com)
Regulators have opened formal reviews amid data concerns
Regulatory agencies have already been scrutinising Tavneos for two separate but related reasons: safety signals involving liver injury and questions over the integrity of clinical trial data. In March and April 2026 the U.S. Food and Drug Administration signalled concerns about data handling in the pivotal ADVOCATE study and sought further information that culminated in a proposal to withdraw approval. The FDA’s review cites alleged post‑unblinding readjudication of key endpoints that affected the trial’s reported results. (fda.gov)
In the European Union the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) initiated a referral review at the end of January 2026 after new information raised questions about the conduct and integrity of the ADVOCATE study. The EMA said it will assess whether the benefit–risk balance for Tavneos remains acceptable based on the full body of evidence. (ema.europa.eu)
Clinical signal focuses on vanishing bile duct syndrome and early onset
Japanese reports and company communications indicate that several of the most severe cases involved vanishing bile duct syndrome (VBDS), a rare hepatobiliary condition that can lead to liver failure. Local reporting has cited figures showing multiple VBDS cases, some of which resulted in death, and noted that many serious liver events occurred within about three months of starting treatment. (bernama.com)
Clinicians in Japan and elsewhere are being urged to intensify liver function monitoring for patients on Tavneos and to discontinue therapy promptly if significant abnormalities appear. Medical product information already recommends periodic liver tests, but health authorities and companies may issue updated or more prescriptive guidance as investigations proceed. (amgen.com)
Implications for patients, prescribers and rare‑disease care
Tavneos is indicated as part of combination regimens for adults with severe, active granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), conditions that can be life‑threatening without effective treatment. For patients with limited options, removing or restricting use of a therapy can be clinically consequential, which is why regulators weigh safety signals against demonstrated benefits in severe disease. (amgen.com)
Physicians treating ANCA‑associated vasculitis are being advised to discuss the emerging information with patients, review recent liver tests, and consider alternative regimens where appropriate. Patient groups and specialist centres will likely play a central role in relaying information and coordinating care while regulators and manufacturers complete their assessments. (amgen.com)
Market and corporate fallout under scrutiny
The safety advisory and pending regulatory decisions have already drawn investor attention, with partner companies and their commercial prospects now under closer observation. Kissei’s pause on new prescriptions in Japan could materially affect local sales of Tavneos, and any regulatory action by the FDA or EMA would have wider commercial repercussions. Analysts are monitoring potential label changes, restricted indications, or even withdrawal scenarios as investigations continue. (ad-hoc-news.de)
Amgen has emphasised that it continues to believe in the drug’s favourable benefit–risk profile based on available data and real‑world experience, while also saying it will keep collaborating with regulators. Any final regulatory outcome will depend on thorough reviews of both the safety reports and the questions raised about the pivotal trial’s data handling. (amgen.com)
The immediate priority for clinicians and patients is careful review and monitoring: clinicians should follow the latest safety notices, perform recommended liver function testing, and discuss alternatives with patients when appropriate. Meanwhile, regulators, Kissei and Amgen continue to gather and analyse data as part of ongoing safety and integrity reviews, and further updates are expected as investigations progress.