Bond.az reports that Amgen Inc (NASDAQ:AMGN) shares fell 2.1% on Friday following developments related to Tavneos, a drug for rare kidney diseases acquired through its $16.6 billion purchase of Horizon Therapeutics in 2023.
Kissei Pharmaceutical Co., Ltd., which holds exclusive rights to develop and commercialize Tavneos in Japan, announced Friday it is urging healthcare professionals to refrain from prescribing the drug to new patients and to carefully assess treatment continuation for existing patients due to severe liver injury concerns.
The Japanese company reported 20 fatal cases associated with the drug in Japan, including 13 deaths linked to Vanishing Bile Duct Syndrome. As of April 27, 2026, 22 severe cases of the syndrome have been reported among an estimated 8,503 patients treated in Japan during the post-marketing period.
The FDA issued a warning on March 31, 2026, about severe drug-induced liver injury in patients taking Tavneos. On April 27, 2026, the FDA proposed withdrawing U.S. approval. The European Medicines Agency initiated a review on January 30, 2026, due to concerns regarding data integrity from the Phase III clinical trial.
Kissei reported sales revenue of 11.524 billion yen for Tavneos in the fiscal year ending March 2026. The drug's approval in Japan remains in effect.
