REFILE-US FDA warns of liver injury cases tied to Amgen's rare disease drug

March 31 (Reuters) - The U.S. Food and Drug Administration said on Tuesday it had identified cases of liver injury in patients taking Amgen's AMGN.O drug for a group of rare autoimmune diseases and urged healthcare providers to closely monitor patients and discontinue the treatment promptly if liver damage is suspected.

The agency said it had identified 76 cases of drug-induced liver injury with evidence suggesting a causal link to Tavneos, including seven cases of vanishing bile duct syndrome, a rare condition that can cause permanent liver damage. Eight deaths were reported among those cases.

The safety warning adds to mounting regulatory scrutiny of Tavneos, which is approved to treat anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis, a group of rare autoimmune diseases that cause inflammation in small- to medium-sized blood vessels.

In January, Amgen said the FDA had asked the company to voluntarily withdraw the drug after concerns emerged during a re-evaluation of primary endpoint data for nine of the 331 patients enrolled in the late-stage trial supporting its approval.

Amgen declined to withdraw the drug, saying at the time it was not aware of any issues with the underlying patient data, remained confident in Tavneos' benefit-risk profile and was working with the FDA on next steps.

The FDA said the median time to onset of drug-induced liver injury was 46 days after starting treatment.

While Tavneos labels in Europe and Australia mention post-marketing cases of vanishing bile duct syndrome, the U.S. prescribing information does not currently warn of it, according to the FDA's website.

In January, the European Medicines Agency said it started a review of Tavneos, "following emerging information that raises questions regarding the data integrity (of its study)."

The FDA approved Tavneos in 2021.

Amgen did not immediately respond to a Reuters request for comment.