Amgen Defends Tavneos' FDA Approval with Duke Data Analysis

Amgen Enlists Duke to Defend Tavneos Against FDA Withdrawal

Amgen is challenging an FDA request to voluntarily withdraw its rare inflammatory disease drug, Tavneos, from the market. The FDA raised concerns regarding patient deaths and liver toxicities, including drug-induced liver injury (DILI) and vanishing bile duct syndrome (VBS), and questioned data integrity from the pivotal Phase 3 ADVOCATE trial. In response, Amgen has commissioned the Duke Clinical Research Institute for an independent re-adjudication of ADVOCATE data, with results expected by June 29, 2026, to support Tavneos' continued approval for ANCA-associated vasculitis. Amgen acquired ChemoCentryx, Tavneos' original developer, for $4 billion in 2022.

• The FDA first requested Tavneos' withdrawal in January 2026, citing issues with ChemoCentryx's primary endpoint evaluation process for nine of 331 patients in the ADVOCATE trial, alongside general liver toxicity concerns. Amgen refused this request, asserting the drug's efficacy and favorable benefit-risk profile, and has since requested a formal hearing with the agency.
• In late March 2026, the FDA escalated its pressure by issuing a safety alert, specifically flagging eight deaths and 76 cases of DILI with a reasonable causal link to Tavneos. Crucially, seven of these DILI cases involved biopsy-confirmed VBS, leading to hospitalization and contributing to three fatalities, which the FDA identified as new, potentially fatal safety concerns beyond those previously known.
• Tavneos is also under review by other regulatory bodies. Japan's Kissei Pharmaceutical, Amgen's partner for Japanese distribution, reported 20 patient deaths since the drug's 2022 launch in Japan, predominantly linked to DILI and VBS, though a direct causal link to Tavneos remains unconfirmed. Separately, the European Medicines Agency (EMA) initiated its own review, also questioning the data integrity of the ADVOCATE trial.
• To bolster its case, Amgen has engaged the Duke Clinical Research Institute to conduct an independent and fully blinded re-adjudication of the ADVOCATE trial data, which commenced in February 2026. The company plans to submit these results, along with data from over a dozen other ongoing or recently completed studies, to the FDA by June 29, 2026, aiming to comprehensively demonstrate Tavneos' overall benefit-risk profile.

Tavneos' Safety Profile Under FDA Scrutiny

Published safety data for Tavneos (avacopan) across ANCA-associated vasculitis studies demonstrates a generally favorable tolerability profile, particularly when compared to traditional glucocorticoid-based regimens. The pivotal ADVOCATE trial and emerging real-world evidence provide comprehensive insights into the drug's safety characteristics, though some population-specific variations have been identified.

• Serious adverse events in the ADVOCATE trial occurred at similar rates between treatment groups, with 37.3% of avacopan patients and 39.0% of prednisone patients experiencing events (excluding worsening vasculitis)

• Avacopan significantly reduced glucocorticoid-related adverse events (RR = 0.78; 95% CI: 0.70-0.87; p <0.0001), particularly decreasing incidence of diabetes, psychiatric complications, and general corticosteroid toxicity

• Real-world Japanese data revealed elevated liver enzyme levels as the most frequent complication, occurring in 38.1% of patients, with overall adverse events reported in 47.6% of patients

• FAERS database analysis identified 33 adverse event signals among 1,128 reports, with most classified as low-priority signals and no high-priority safety concerns detected

• Population-specific safety variations emerged, with Japanese patients showing significantly higher risk of liver dysfunction compared to American patients (p<0.001), while alopecia occurred exclusively in American populations

• Serious infection rates in real-world studies averaged 14% (95% CI: 0.10-0.18), with two infection-related serious adverse events reported in Japanese cohorts, including one fatal opportunistic infection

• The ongoing AvacoStar study is systematically evaluating long-term safety over 7 years, focusing on medical events of special interest including liver injury, cardiac safety, serious infections, and malignancy, with final results expected in 2031

Addressing Unmet Needs in ANCA-Associated Vasculitis

Current treatment approaches for ANCA-associated vasculitis face significant challenges that impact patient outcomes and quality of life. Despite therapeutic advances that have reduced mortality, conventional immunosuppressive treatments remain only partially effective and contribute to substantial morbidity. These limitations underscore the high unmet medical need in AAV management.

• High relapse rates persist despite modern therapies - 50% of patients experience relapse within 5 years, with 30-50% still relapsing despite significant advances in treatment, and 32.7% of patients who achieve remission subsequently experience disease recurrence

• Treatment-related toxicity significantly contributes to morbidity and mortality - Conventional immunosuppressive treatments cause progressive organ damage and disability in the majority of patients, with infection being the greatest cause of early mortality rather than uncontrolled vasculitis

• Glucocorticoid-associated complications remain problematic - Long-term glucocorticoid use is responsible for the majority of adverse effects, with patients treated for >12 weeks showing trends toward more serious infections (21% vs 7%) compared to shorter treatment durations

• Treatment resistance affects a substantial patient subset - 10.7% of AAV patients demonstrate treatment resistance, with persistent autoreactive B-cells and long-lived tissue-resident plasma cells contributing to refractory disease and relapse

• Disease monitoring and assessment present ongoing challenges - Existing remission definitions underestimate ongoing disease activity, interpretation of residual symptoms in the absence of overt inflammation is difficult, and the optimal duration of immunosuppressive therapy remains uncertain

• Economic burden concentrates in high-risk patient populations - Real-world cost analyses show 71% of costs attributable to patients experiencing infections and 60% to those with multi-comorbidity, both strongly associated with corticosteroid use

• Knowledge gaps limit personalized treatment approaches - Robust predictors of individual clinical course are lacking, preventing tailored treatment regimens, while incomplete understanding of genetic background and pathophysiology in conditions like granulomatosis with polyangiitis hampers therapeutic development

Re-evaluating ADVOCATE Data to Defend Tavneos

Recent landmark trials in ANCA-associated vasculitis have provided critical evidence for optimizing therapeutic approaches and patient outcomes. These studies encompass various treatment strategies including complement inhibition, anti-CD20 therapy, and glucocorticoid reduction protocols across diverse patient populations.

The Future of Tavneos: A Critical Test for Glucocorticoid-Sparing AAV Therapy

The landscape of ANCA-associated vasculitis (AAV) treatment has seen significant evolution, driven by the critical need to reduce the severe toxicities associated with long-term glucocorticoid use. Avacopan (Tavneos), an oral C5a receptor antagonist, emerged as a pivotal advancement, demonstrating in the ADVOCATE trial its ability to achieve noninferior remission induction and superior sustained remission compared to prednisone taper, while significantly reducing glucocorticoid exposure. This has translated into improved health-related quality of life for patients and better renal function recovery, particularly in those with acute kidney injury. Consequently, avacopan has been integrated into major clinical guidelines, including those from KDIGO and EULAR, as a valuable glucocorticoid-sparing alternative.

However, this promising trajectory faces a significant challenge as the FDA has raised concerns regarding patient deaths and specific liver toxicities, including drug-induced liver injury (DILI) and vanishing bile duct syndrome (VBS), alongside questions about data integrity from the pivotal ADVOCATE trial. This regulatory scrutiny introduces a critical juncture for Tavneos and Amgen, who acquired the drug's original developer for $4 billion. Amgen's strategic response—commissioning an independent re-adjudication of the ADVOCATE data—is a high-stakes maneuver to defend the drug's continued approval and protect its substantial investment. The outcome of this re-adjudication, expected in mid-2026, will be instrumental in determining Tavneos' long-term market access and its standing within AAV treatment paradigms.

While the ADVOCATE trial demonstrated a comparable rate of serious adverse events between avacopan and prednisone, the FDA's specific focus on liver safety and patient outcomes necessitates a thorough re-evaluation. The ongoing AvacoStar study, designed to prospectively assess long-term safety including liver injury over seven years, underscores the importance of comprehensive real-world data to fully characterize the drug's profile. This situation highlights the continuous need for robust post-marketing surveillance and the critical role of data integrity in maintaining regulatory and physician confidence, especially for novel therapies addressing complex rare diseases.