According to a safety notice issued Friday by partner Kissei Pharmaceutical, around 20 deaths associated with serious liver dysfunction have been reported in Japan among patients treated with Tavneos, the rare disease drug developed by Amgen.
Kissei Pharmaceutical has advised doctors to stop prescribing Tavneos to new patients and to review ongoing treatments due to concerns over potential liver damage.
The company also stated that some of the deaths reported as of April 27 were associated with a severe liver condition that destroys bile ducts, although a direct connection to Tavneos had not been confirmed in every case.
Tavneos, which is approved to treat ANCA-associated vasculitis a group of rare autoimmune disorders that cause inflammation in small- to medium-sized blood vessels is facing increasing regulatory attention.
Kissei Pharmaceutical stated that most severe liver injury cases were reported within the first three months after patients began treatment.
Kissei Pharmaceutical said that around 8,503 patients in Japan have been treated with Tavneos since its launch in 2022 and advised doctors to regularly monitor liver function and immediately discontinue the drug if abnormalities are found.
The development was first reported earlier Friday by The Wall Street Journal.
U.S. regulators have already raised concerns over serious liver injury cases linked to Tavneos and have started taking steps toward withdrawing the treatment, although Amgen continues to maintain that the drug has a favorable risk profile.
Tavneos received approval in the United States in 2021 and was launched in Japan the following year. Amgen acquired the drug through its $3.7 billion purchase of developer ChemoCentryx in 2022.
Earlier this year, the U.S. Food and Drug Administration asked Amgen to voluntarily remove Tavneos from the U.S. market, but the company refused.
The regulator has since initiated formal withdrawal proceedings after identifying dozens of liver injury cases worldwide, with many of the reports originating from Japan.
