Amgen’s rare disease drug Tavneos tied to 20 deaths in Japan

Amgen's Tavneos Linked to 20 Deaths in Japan Amid Data Manipulation Claims

Amgen's autoimmune drug Tavneos has been linked to 20 deaths in Japan since its 2022 launch, primarily due to vanishing bile duct syndrome (VBS), a complication of drug-induced liver injury (DILI). Kissei Pharmaceutical, Amgen's Japanese partner, issued a safety alert discouraging new prescriptions and recommending careful assessment for existing patients. Amgen stated these deaths occurred among over 8,500 patients treated in Japan and that a causal relationship isn't always determined. This follows previous FDA concerns in the U.S., where 76 VBS cases and 8 deaths were flagged with a "reasonable evidence of causal association," and allegations of manipulated data supporting the drug's 2021 approval. The FDA had previously requested Tavneos be pulled from the market.

• Safety Concerns in Japan: Kissei Pharmaceutical, Amgen's Japanese partner, reported 20 deaths among patients treated with Tavneos since its 2022 launch in Japan. Most mortalities were linked to vanishing bile duct syndrome (VBS), a severe form of drug-induced liver injury (DILI). Kissei has advised healthcare professionals to refrain from prescribing Tavneos to new patients and to carefully evaluate continued treatment for existing ones, initiating an information campaign to communicate these risks.
• Amgen's Context and U.S. Data: Amgen provided context, noting the 20 deaths occurred among over 8,500 patients treated with Tavneos in Japan, emphasizing that a causal relationship with the product could not always be determined. The company also stated no known Tavneos-linked deaths from serious liver injury have occurred in the U.S., despite the FDA flagging 76 VBS cases and 8 deaths with "reasonable evidence of causal association" in March.
• FDA Allegations and Regulatory Scrutiny: The FDA has intensified its scrutiny of Tavneos, having previously requested its market withdrawal in January due to issues with the re-adjudication of the primary endpoint in its pivotal study. More recently, the agency alleged that "doctored data" were filed to support the drug's 2021 approval, claiming manipulated results made the drug appear effective when the original analysis did not support this conclusion, thus questioning the drug's demonstrated efficacy.
• Acquisition and Franchise Challenges: Amgen acquired ChemoCentryx, the original developer of Tavneos, in 2022 for $3.7 billion. The recent safety alerts and FDA allegations pose significant challenges for the Tavneos franchise, which Amgen continues to defend as an "important and effective medicine" with a favorable benefit-risk profile, despite the ongoing controversies surrounding its safety and approval process.

The Pivotal Tavneos Trial: Design Under Scrutiny

Recent clinical trials in autoimmune diseases have employed diverse study designs to evaluate novel therapeutics across multiple disease areas. These trials have utilized standardized endpoints specific to each condition while maintaining consistent safety assessment parameters across all studies.

Tavneos Safety Profile: Emerging Liver Injury Concerns

Published safety and tolerability data for Tavneos (avacopan) demonstrates a generally favorable profile compared to traditional glucocorticoid-based regimens, though emerging concerns about liver injury warrant attention. Meta-analysis of clinical trials shows avacopan substantially reduces glucocorticoid-related adverse events without increasing serious infections, mortality, or treatment discontinuations, while real-world pharmacovigilance data reveals specific safety signals requiring monitoring.

• Liver injury represents the most significant safety concern, occurring in 16.7-40.9% of cases in Japanese cohorts, with elevated liver enzyme levels observed in 38.1% of patients in real-world studies and Japanese patients exhibiting significantly higher risk of liver dysfunction compared to American patients (p<0.001)

• Large-scale pharmacovigilance analysis identified 33 adverse event signals from 1,128 avacopan-related reports, including five new potential adverse events (alopecia, increased appetite, hyperaesthesia teeth, oesophageal disorder, and muscle atrophy) with median onset time of 86.5 days

• Serious adverse events occur at comparable rates to standard therapy, with 37.3% of avacopan patients versus 39.0% of prednisone patients experiencing serious adverse events excluding worsening vasculitis in the ADVOCATE trial

• Drug discontinuation rates remain substantial at 42.9% in Japanese real-world studies, though patients still achieved comparable remission rates at 6 months and sustained remission at 12 months despite early discontinuation

• Infection-related safety profile shows mixed signals, with meta-analysis demonstrating no significant increase in serious infections, but real-world data revealing sepsis and pulmonary hemorrhage as newly identified adverse events, plus two serious infection-related events in diffuse alveolar hemorrhage patients

• Geographic and demographic variations in safety patterns emerged from FAERS database analysis of 7,141 adverse events, showing higher adverse event rates in female patients, increased mortality in males aged ≥65 years, and population-specific adverse events like alopecia occurring exclusively in American patients

Addressing Unmet Needs in Autoimmune Disease Treatment

Current autoimmune disease treatments face significant therapeutic limitations that underscore the urgent need for more advanced approaches. Conventional immunomodulatory and immunosuppressive therapies often fail to provide cures and have restricted efficacy in symptom management, leaving many patients with progressive disability.

• Limited efficacy of conventional therapies - Immunomodulatory and immunosuppressive drugs used for systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis frequently fall short of providing cures and have significant limitations in symptom management

• Challenges in translating research to clinical practice - A persistent gap exists between basic research findings and therapeutic trial implementation, hindering the development of evidence-based interventions

• Hematopoietic stem cell transplantation limitations - Despite theoretical promise for reversing or modulating autoimmune disease, this approach faces substantial barriers including economic constraints, healthcare delivery challenges, and unresolved efficacy and safety concerns

• Disease-specific diagnostic requirements - For conditions like myocarditis and inflammatory cardiomyopathies, effective treatment requires standardized diagnostic evaluation of biopsy specimens rather than clinical examination alone, and treatment efficacy depends on identifying treatable causes before irreversible myocardial injury occurs

• Anti-CD20 therapy safety concerns - Monoclonal antibodies widely used for B-cell malignancies and autoimmune diseases present insufficiently characterized ocular toxicity, requiring careful monitoring particularly in multiple sclerosis patients, with over half of ocular adverse events occurring within 15 days of treatment initiation

• Methodological challenges in emerging research - Microbiome research faces significant obstacles including methodological inconsistencies, limited longitudinal studies, and result heterogeneity, highlighting the need for standardized protocols and larger controlled clinical trials

AAV Treatment: Balancing Innovation with Emerging Safety Signals

Avacopan (Tavneos) emerged as a promising therapeutic option for ANCA-associated vasculitis (AAV), offering a much-needed glucocorticoid-sparing strategy. Clinical trials demonstrated its non-inferiority to prednisone for remission and superiority for sustained remission, significantly reducing the burden of corticosteroid-related toxicities that have long plagued AAV patients. This innovation was poised to revolutionize AAV management, providing a pathway to less reliance on high-dose steroids.

However, the recent safety alert in Japan, linking Tavneos to 20 deaths primarily due to vanishing bile duct syndrome (VBS), a severe form of drug-induced liver injury (DILI), casts a significant shadow over its clinical utility. This is not an isolated concern; previous FDA reviews in the U.S. had already identified VBS cases and deaths with a "reasonable evidence of causal association," even requesting the drug be pulled from the market at one point. The literature supports these concerns, with liver damage and elevated liver enzymes frequently reported as adverse events, and real-world pharmacovigilance data specifically highlighting a higher risk of liver dysfunction in Japanese patients.

This situation underscores the critical importance of robust post-marketing surveillance, especially for novel therapies. While avacopan's mechanism targeting the C5a receptor offers a valuable alternative to traditional immunosuppression, the emergence of such severe, potentially fatal, hepatotoxicity demands immediate and thorough investigation. Companies must navigate the delicate balance of bringing innovative treatments to market while ensuring patient safety through comprehensive data collection and transparent communication. The long-term safety profile, particularly beyond the initial 52-week trial period, and optimal concomitant glucocorticoid use remain areas requiring further study. For clinicians, this necessitates heightened vigilance in monitoring liver function, especially in high-risk populations, and careful patient selection to maximize the drug's benefits while minimizing its serious risks.