Amgen (Nasdaq: AMGN) submitted data and analyses to the US FDA on July 23, 2026, in support of its request for a formal hearing on Tavneos (avacopan), the company's oral complement C5a receptor inhibitor approved for severe active ANCA-associated vasculitis. The submission directly contests the FDA's April 2026 proposal to withdraw Tavneos from the US market, which alleged that the original approval application contained untrue statements of material fact and that the drug had not been shown to be effective for its approved use.
Tavneos generated USD 119 million in US sales in Q1 2026, a 32% year-over-year increase, making the withdrawal proposal a commercially material threat. More broadly, Tavneos is one of very few approved treatment options for adults with granulomatosis with polyangiitis and microscopic polyangiitis — the two principal forms of ANCA-associated vasculitis — a rare, potentially life-threatening disease in which immune-mediated destruction of small blood vessels can cause irreversible kidney damage, pulmonary hemorrhage, and organ failure. Approximately 80–90% of patients present with kidney- or organ-threatening manifestations, and many are left with significant chronic kidney disease.
The FDA's withdrawal proposal, published in April 2026, cited new information indicating that unblinded study personnel manipulated results of the pivotal Phase III ADVOCATE trial so the drug appeared effective when the original analysis did not support that conclusion. Amgen acquired ChemoCentryx, the original developer and NDA holder, in 2022. The same data integrity concerns prompted the EMA's Committee for Medicinal Products for Human Use to recommend revoking Tavneos' EU marketing authorization in June 2026 following an Article 20 procedure.
The core of Amgen's FDA submission rests on a 2026 independent, fully blinded re-adjudication of the ADVOCATE primary outcomes, conducted by Duke Clinical Research Institute. The re-adjudication confirmed noninferiority of Tavneos versus a prednisone taper for remission at Week 26 (68.1% vs 67.1%; difference 2.2%; 95% CI, −7.5 to 11.9) and for sustained remission at Week 52 (61.4% vs 52.4%; difference 9.8%; 95% CI, −0.3 to 19.9). Superiority at Week 52 was not demonstrated in the re-adjudication — in contrast to the original ADVOCATE analysis, which reported a 12.5% difference (95% CI, 2.6% to 22.3%) favoring Tavneos. Amgen argues the directional consistency between the two analyses supports the drug's efficacy.
Amgen's submission also draws on a systematic literature review and meta-analysis of 71 real-world studies involving more than 2,200 patients, which reported 87% remission at six months, 93% remission at 12 months, and a 7% relapse rate at 12 months. Only 36% of patients remained on glucocorticoids at both six and 12 months. A separate large comparative effectiveness study found lower steroid exposure at six months and fewer relapses at 12 months in patients treated with Tavneos plus standard of care versus standard of care alone.