Amgen is asking for an independent review as the FDA weighs whether to withdraw the approval of Tavneos (avacopan), according to the company’s response strategy. The dispute stems from FDA concerns tied to alleged safety risks and claims of manipulation in clinical trial evidence tied to the drug’s originating developer, ChemoCentryx. The situation underscores how rare-disease approvals can be vulnerable to re-litigation of trial integrity allegations—especially when misconduct claims intersect with regulatory endpoints and ongoing patient access. For Amgen, the immediate objective is to preserve the label while the review process evaluates the underlying evidentiary record. The case also highlights a broader operational risk for sponsors that rely on legacy datasets or third-party development histories when responding to FDA enforcement actions.