U.S. regulators revisited pivotal-trial adjudication issues and asked Amgen to withdraw Tavneos (avacopan), citing concerns tied to re-adjudicated endpoint data. Amgen publicly refused the request, saying it will contest the agency’s conclusions and maintain product availability for patients with ANCA-associated vasculitis. The dispute resurrects years-old trial questions and highlights regulatory leverage over approval integrity and post‑approval oversight. Amgen said it is engaging with FDA and stands by the underlying data and benefit-risk profile. The outcome matters to clinicians managing rare autoimmune disease and to companies holding post‑market commitments; a forced withdrawal would set a high bar for agency intervention based on historical trial adjudication.