Regulatory tensions escalated after the FDA asked Amgen to withdraw Tavneos (avacopan) from the market; Amgen declined. The agency questioned processes used by the originator, Chemocentryx, to re‑adjudicate primary endpoint results for nine patients in the pivotal trial and raised hepatotoxicity concerns. Amgen, which acquired the asset via its 2022 Chemocentryx purchase, said it is unaware of data issues and will not remove the drug while the company and regulators resolve disputes over benefit‑risk and trial conduct.