Twenty Tavneos patients have died in Japan since the drug’s 2022 launch, Amgen’s Japanese distributor Kissei Pharmaceutical disclosed Friday. Most deaths were linked to vanishing bile duct syndrome (VBS), a complication of drug-induced liver injury. Kissei urged doctors to stop prescribing Tavneos to new patients and recommended informing those already on treatment of the liver risks.
Amgen pushed back, noting the 20 deaths came from over 8,500 Japanese patients and that causal links weren’t confirmed in all cases. The FDA had already flagged 76 VBS cases and 8 U.S. deaths in Tavneos patients in March, saying the liver toxicities had “reasonable evidence of causal association” with the drug. Amgen says no U.S. deaths from serious liver injury have been confirmed as Tavneos-linked.
The Japan deaths land on top of a deeper fight over whether Tavneos should exist at all. In January, the FDA asked Amgen to pull the drug from the market, citing problems with how ChemoCentryx re-adjudicated the primary endpoint in the pivotal approval study. Amgen refused. Last month, the FDA alleged that unblinded study personnel manipulated the trial results to make Tavneos look effective when the original analysis didn’t support that conclusion. The agency now says it “can no longer conclude that there is, or has ever been, a valid demonstration that Tavneos is effective.”
Amgen paid $3.7 billion for ChemoCentryx, and Tavneos by extension, in 2022.
— Sarah Chen