Avacopan for the Treatment of ANCA-Associated Vasculitis: The Primary Endpoints Readjudication

Background The phase 3 ADVOCATE trial evaluated the efficacy and safety of avacopan in patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA). Concerns raised regarding the 2019 primary endpoint adjudication process prompted a blinded, independent readjudication of all participants' primary outcomes, the results of which are described here. Methods Patients with GPA or MPA were randomized 1:1 to receive oral avacopan 30 mg twice daily or oral prednisone on a scheduled taper, each in combination with rituximab- or cyclophosphamide-based standard of care. In 2026, the Duke Clinical Research Institute Clinical Events Classification group conducted an independent, blinded committee re-adjudicated the Birmingham Vasculitis Activity Score (BVAS), relapse, and remission from weeks 26 through 52 using procedures aligned with the original adjudication charter. The primary endpoints were remission at week 26 and sustained remission at week 52. As per the original analysis plan, noninferiority and superiority were declared if the lower bounds of the 95% confidence interval (CI) for the difference in the primary outcome rates between avacopan and a prednisone taper were greater than -20.0 and 0.0 percentage points, respectively. Results Among 330 participants in the intent-to-treat population, remission at week 26 was achieved by 68.1% (113/166) and 67.1% (110/164) of participants in the avacopan and prednisone taper groups, respectively, in the 2026 readjudication (adjusted difference: 2.2%; 95% CI, -7.5, 11.9), compared with 72.3% (120/166) and 70.1% (115/164) in the 2019 primary outcome adjudication (adjusted difference: 3.4%; 95% CI, -6.0, 12.8). Sustained remission at week 52 was achieved by 61.4% (102/166) and 52.4% (86/164) of participants, respectively, in the 2026 readjudication (adjusted difference: 9.8%; 95% CI, -0.3, 19.9), compared with 65.7% (109/166) and 54.9% (90/164) in the 2019 readjudication (adjusted difference: 12.5%; 95% CI, 2.6, 22.3). Concordance between the 2019 and 2026 adjudications was 95.2% for remission and 93.6% for sustained remission. Conclusion The re-analysis of ADVOCATE based on the 2026 readjudication further supports the efficacy of avacopan for GPA/MPA. Non-inferiority of avacopan versus a prednisone taper was confirmed at weeks 26 and 52 despite a median 81% reduction in glucocorticoid exposure observed in the avacopan versus prednisone taper groups. While a consistent numerical difference favoring avacopan at week 52 was observed in the 2019 and 2026 analyses, this difference did not reach statistical superiority.