TL;DR
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A multicenter Italian registry study reported remission, improved kidney-function measures and lower corticosteroid use among patients with ANCA-associated vasculitis treated with avacopan. The findings add real-world evidence but cannot settle questions raised by the reanalysis of the drug’s pivotal trial or concerns about liver toxicity.
A multicenter Italian registry study found that most patients with antineutrophil cytoplasmic antibody-associated vasculitis treated with avacopan reached clinical remission, with kidney-function measures improving and corticosteroid doses falling. The findings offer real-world evidence amid questions about the drug’s pivotal trial, but the study was small and uncontrolled and does not resolve concerns about safety.
The study, reported in ACR Open Rheumatology by Luca Quartuccio of the University of Udine and colleagues, identified 46 patients in Italy who started avacopan between 2022 and 2024. Of those, 32 had received treatment for at least a year. In that group, all but one achieved clinical remission, defined as a Birmingham Vasculitis Activity Score of zero. The researchers reported that 55% stopped corticosteroids entirely.
Across the cohort, mean daily corticosteroid use fell from 23 milligrams to 5 milligrams in prednisone equivalents by week 12, a reduction of nearly 80%. Among patients followed to week 52, median estimated glomerular filtration rate rose from 30.5 to 53.5 milliliters per minute per 1.73 square meters. That measure indicates improved kidney function, though the reported median remained below the study’s cited threshold of 60 for normal kidney function.
Patients were followed for a mean of 61 weeks, with some followed for as long as 130 weeks. Nine of the 46 stopped avacopan: three because symptoms worsened, four because of infections, and two for other reasons. Three patients relapsed; each had a history of relapses before starting treatment. One patient died from a fungal infection after receiving rituximab to control returning symptoms. The report does not establish that avacopan caused the infections or death.
Real-World Findings and Their Limits
The results matter because avacopan is intended to help control a disease that can damage organs, particularly the kidneys, while reducing reliance on corticosteroids. Long-term steroid use carries its own risks, so the reported drop in steroid exposure is clinically relevant if it can be reproduced in larger, rigorous studies.
But these results do not prove that avacopan caused the observed improvements. The registry had no control group, included only 46 patients, and participants also received other immune-suppressing treatment, usually rituximab, sometimes with cyclophosphamide. The favorable outcomes may inform treatment decisions and future research, but they cannot by themselves answer questions about comparative effectiveness or safety.
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Trial Scrutiny and Regulatory Actions
Avacopan, sold as Tavneos, was approved by the U.S. Food and Drug Administration in 2021 for ANCA-associated vasculitis. The drug blocks complement receptor signaling, a pathway involved in inflammation. The disease causes blood-vessel inflammation and can affect the kidneys, lungs and other organs; treatment has commonly relied on corticosteroids alongside other immune-suppressing medicines.
Confidence in the drug’s efficacy came under scrutiny after findings from its main registration trial were re-adjudicated following unblinding, changing a missed endpoint to a successful one. The New England Journal of Medicine later retracted the paper reporting those findings. According to the source report, the FDA asked current manufacturer Amgen to withdraw avacopan, citing new liver-toxicity information as well as the re-adjudication. Amgen had not agreed, and the FDA had not formally ordered withdrawal at the time of that report. European regulators revoked the drug’s authorization in August 2026.
The Italian researchers said independent prospective real-world studies are particularly important when trial findings are in question. Their registry contributes observational evidence, but it does not replace a randomized trial or resolve the integrity concerns surrounding the pivotal study.
“Evidence from independent prospective real-world studies is particularly important to assess the effectiveness and safety of avacopan and its mechanism of action.”
— Luca Quartuccio and colleagues, as quoted in the study report
Efficacy and Liver Safety Questions
The registry cannot determine how much of the improvement was due to avacopan rather than other treatments, patient selection or the course of the disease. Its small size and lack of a comparison group also limit conclusions about outcomes across different patient groups. The report notes that two patients had grade 1 liver-enzyme elevations that did not interrupt treatment, but provides limited detail on liver outcomes overall.
That limited safety information is important because the source report says the pivotal trial recorded treatment discontinuation for adverse liver effects in 4.2% of avacopan recipients and serious hepatic reactions in 5.4%. It remains unclear whether the registry can meaningfully assess uncommon or delayed harms. The regulatory status in the United States could also change; the source report said the FDA had requested withdrawal but had not formally ordered it.
Further Evidence and FDA Decisions
Further follow-up and larger independent studies would be needed to test whether the remission, kidney-function and steroid-reduction findings persist across a broader group of patients, and to characterize liver risks more fully. The registry report alone does not establish what treatment approach is best for an individual patient.
In the United States, the next regulatory development depends on whether Amgen changes its position or the FDA takes formal action. The source report did not specify a deadline or an announced next agency step. Clinicians and patients may also need to track any updated regulator communications and published evidence as they emerge.
Key Questions
What did the Italian study find about avacopan?
The researchers reported that all but one of 32 patients treated for at least a year achieved clinical remission. They also reported lower corticosteroid use and improved median kidney-function measures, but the study was small and uncontrolled.
Does this study prove avacopan is effective?
No. A registry study without a control group can describe outcomes but cannot establish that avacopan caused them or determine how it compares with other treatment.
Why has avacopan’s efficacy been questioned?
Findings from its main registration trial were re-adjudicated after unblinding, changing a missed endpoint to a success. The journal that published the trial paper later retracted it, prompting renewed scrutiny of the evidence.
What safety concerns remain?
Liver toxicity remains a concern. The Italian report described two mild liver-enzyme elevations, but its size and limited liver-outcome information cannot settle the drug’s hepatic safety profile.
What is avacopan’s U.S. regulatory status?
According to the source report, the FDA had asked Amgen to withdraw avacopan, but had not formally ordered a withdrawal at the time of publication. The situation may change as the company or agency takes further action.
Source: rss
