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 offer real-world evidence but do not resolve questions raised by problems in the drug’s pivotal trial or concerns about liver toxicity.
A multicenter Italian registry study found that most of the patients treated with avacopan for ANCA-associated vasculitis achieved clinical remission, while average corticosteroid doses fell and kidney-function measures improved. The results offer real-world evidence for a drug whose efficacy has come under renewed scrutiny, but the study was small and uncontrolled and does not settle questions about its effectiveness or safety.
The study team, led by Luca Quartuccio of the University of Udine, identified 46 patients who began avacopan in Italy between 2022 and 2024. The report said that 32 patients had received the drug for at least a year; among them, all but one achieved clinical remission. Remission was defined as a Birmingham Vasculitis Activity Score of zero.
Across the cohort, mean daily corticosteroid doses fell from 23 milligrams to 5 milligrams in prednisone equivalents by week 12, an average reduction of nearly 80%. At week 52, 55% of the longer-treated group had stopped corticosteroids. Kidney measures also improved: median estimated glomerular filtration rate rose from 30.5 to 53.5 milliliters per minute per 1.73 square meters between treatment baseline and week 52. The latter figure remained below the study’s stated threshold for normal kidney function of 60.
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. Seven additional patients temporarily paused treatment. The researchers reported three relapses; all three patients had a history of relapse before starting the drug.
Evidence Beyond the Pivotal Trial
The results matter because avacopan’s clinical record is being reconsidered after concerns about the integrity and analysis of its pivotal registration trial. The New England Journal of Medicine retracted the trial paper after findings were re-adjudicated following unblinding; the revised analysis changed a missed endpoint into a success. The registry study is independent real-world evidence, but it cannot replace a controlled trial or by itself verify the drug’s benefit.
The reported steroid reduction may also matter to patients because long-term corticosteroid use can bring serious adverse effects. At the same time, kidney involvement can cause major organ damage in ANCA-associated vasculitis, making the rise in kidney-function measures relevant. The study does not establish that avacopan alone caused these outcomes: patients also received other immune-suppressing treatments, including rituximab, and there was no comparison group.
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Trial Scrutiny and Regulatory Actions
ANCA-associated vasculitis is an autoimmune disease that inflames blood vessels and can damage organs, particularly the kidneys. Steroids have long been a core treatment. Avacopan blocks a complement pathway involved in inflammation and received U.S. approval in 2021.
Questions about the pivotal trial have coincided with safety concerns. The source report says the U.S. Food and Drug Administration asked manufacturer Amgen to withdraw avacopan, citing new information about liver toxicity as well as the trial re-adjudication. Amgen has not agreed, and the FDA had not formally ordered withdrawal at the time of the report. European regulators revoked the drug’s authorization in August 2026.
The Italian study included newly diagnosed and relapsing patients, most of whom received rituximab, either alone or with cyclophosphamide. That treatment context is important: the reported outcomes reflect care involving multiple therapies, not a clean test of avacopan as a standalone treatment.
“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
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Safety and Causal Questions Remain
The registry cannot establish whether avacopan produced the improvements because it had no control group, involved only 46 patients and included other treatments. The report also provides limited information about liver outcomes. Two patients had grade 1 liver-enzyme elevations that did not lead to stopping treatment, but that small observation cannot rule out more serious risks.
The source report notes that in avacopan’s phase III trial, 4.2% of patients discontinued because of adverse liver effects and 5.4% had serious hepatic reactions. The Italian study’s small size makes it poorly suited to detect uncommon harms. The regulatory status and the FDA’s next steps also remain unsettled in the account provided: the FDA had requested withdrawal, but had not formally ordered it.
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Regulatory Review and Further Evidence
Further follow-up and larger, independent studies would help clarify whether the remission and kidney-function patterns persist, how outcomes differ between newly diagnosed and relapsing patients, and how frequently liver or other serious adverse events occur. The study report describes follow-up extending to 130 weeks for some participants, but the results summarized here do not provide a complete long-term safety picture.
Readers should also watch for any formal FDA action and developments in the drug’s market status. Until stronger comparative evidence is available, the Italian findings are best read as encouraging observations from routine care—not as proof that concerns about avacopan’s efficacy or safety have been resolved.
ANCA-associated vasculitis management
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Key Questions
What did the Italian study find?
Among 32 patients treated for at least a year, all but one achieved clinical remission. The study also reported lower corticosteroid doses and improved median kidney-function measures, while noting that the design cannot establish cause and effect.
Does the study prove that avacopan works?
No. It was a small, uncontrolled registry study, and patients received other immune-suppressing treatments. Its results provide real-world observations but do not prove that avacopan caused the outcomes.
Why is avacopan’s evidence under scrutiny?
The pivotal trial’s findings were re-adjudicated after data were unblinded, changing a missed endpoint into a success. The New England Journal of Medicine later retracted the paper reporting the findings.
What safety concern remains?
Liver toxicity remains a concern. The Italian report described two mild liver-enzyme elevations, but its small sample cannot rule out uncommon or serious harms. The source report also cites liver-related discontinuations and serious reactions in the phase III trial.
What is the drug’s regulatory status?
According to the source report, the FDA had asked Amgen to withdraw avacopan but had not formally ordered a withdrawal; Amgen had not agreed. European regulators revoked its authorization in August 2026.
Source: rss
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