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# Study Finds Severe Liver Injury in Small Number of Avacopan Patients
- URL: https://www.fdaweb.com/study-finds-severe-liver-injury-in-small-number-of-avacopan-patients/
- Published: 2026-08-24T12:00:00.000Z
- Updated: 2026-09-14T12:05:54.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5161671

As Amgen continues its bid to prevent the withdrawal of Tavneos (avacopan) in the U.S., a new study using a U.S. rheumatology registry has found that while liver enzyme elevations were uncommon among patients treated with avacopan, it identified two cases of drug-induced liver injury (DILI), including one case of severe, histologically confirmed hepatocellular injury.

Published in the 8/24 *Arthritis & Rheumatology*, the study evaluated real-world incidence of hepatic enzyme abnormalities and confirmed DILI among U.S. patients receiving avacopan, an oral C5a receptor inhibitor approved in 2021 for the treatment of ANCA-associated vasculitis (AAV).

The[ study ](https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.70304?ref=fdaweb.com)comes as FDA reportedly continues to reassess the drug's liver safety profile. The researchers noted that FDA has received reports of 76 worldwide cases of drug-induced liver injury associated with avacopan, including 66 in Japan and five in the U.S. The researchers said the U.S. risk of liver injury had not previously been quantified using real-world data.

Researchers used data from the Rheumatology Informatics System for Effectiveness Registry and identified 238 patients with AAV who received at least one avacopan prescription between 10/2021 and 3/2025\. Hepatic enzyme elevations were defined using FDA guidance as AST or ALT levels greater than three times the upper limit of normal, alkaline phosphatase greater than twice the upper limit of normal, or total bilirubin greater than 2 mg/dL.

Among the 238 patients, five experienced elevated AST, three had elevated ALT, four had elevated alkaline phosphatase and two had elevated total bilirubin during treatment, according to researchers. The corresponding incidence rates per 100 person-years were 4.24 for AST elevations, 2.67 for ALT elevations, 3.56 for alkaline phosphatase elevations and 1.80 for total bilirubin elevations.

Two patients, representing 0.8% of the study population, were determined to have DILI. Despite the identification of severe DILI, the researchers found that overall hepatic enzyme elevations were infrequent in the U.S. cohort.

The findings, they said, support continued vigilance, particularly early in treatment, as regulators continue to reassess avacopan's safety profile.

Last month, Amgen submitted to FDA new scientific data and analyses as part of its formal request for an FDA hearing, contending that the available evidence satisfies the statutory standard for substantial evidence of effectiveness ([see earlier story](https://fdaweb.com/login.php?sa=v&aid=D5161514&cate=&stid=%241%24gV3.ps1.%244vlB5lwuot8YZrufdm.JJ.&ref=fdaweb.com)).

Amgen has argued that the treatment continues to demonstrate a favorable benefit-risk profile for patients with severe active ANCA-associated vasculitis (AAV), a rare and potentially life-threatening autoimmune disease.