The U.S. Food and Drug Administration (FDA) has warned patients and healthcare providers about serious and sometimes fatal liver injuries tied to Amgen Inc.’s (NASDAQ:AMGN) Tavneos (avacopan), citing postmarketing data that point to new safety concerns beyond those identified in clinical trials.

Tavneos, approved in October 2021, is used in combination with glucocorticoids and other therapies to treat adults with severe active ANCA-associated vasculitis, a rare autoimmune condition affecting small- to medium-sized blood vessels.

New Safety Signal Emerges For Tavneos

The agency said cases of drug-induced liver injury (DILI), including a rare but severe condition known as vanishing bile duct syndrome (VBDS), have been reported in patients treated with Tavneos.

VBDS involves progressive destruction of bile ducts, potentially leading to impaired bile flow and permanent liver damage.

Symptoms may include jaundice, itching, and fatigue.

Postmarketing Data Highlights Serious Outcomes

While hepatotoxicity was previously documented in premarket studies and included in product labeling, the FDA said reports of VBDS and fatal DILI cases represent newly identified risks.

A review of postmarketing data, including submissions from the drug's global safety database, published literature, and the FDA Adverse Event Reporting System, identified 76 cases of DILI with a reasonable causal link to avacopan use through October 9, 2024.

Among these, 74 cases involved serious outcomes, including 54 hospitalizations and eight deaths.

Laboratory data from 60 cases showed that most patients experienced cholestatic or mixed patterns of liver injury, often marked by elevated alkaline phosphatase and bilirubin levels.

The median time to onset of liver injury was 46 days after starting treatment, with a range of 22 to 140 days.

Rare Cases Raise Additional Concerns

Of the total cases, seven involved biopsy-confirmed VBDS linked to avacopan. All seven patients required hospitalization, and three cases resulted in death.

Among these cases, four showed cholestatic or mixed liver injury patterns, while three were hepatocellular. The median time to onset was also 46 days, ranging from 33 to 59 days.

FDA Continues Monitoring

The FDA said it will continue monitoring postmarketing reports of liver injury associated with avacopan and will provide updates as new information becomes available.

AMGN Stock Price Activity: Amgen shares were up 0.51% at $350.68 at the time of publication on Tuesday, according to Benzinga Pro data.

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