Immune‐Related Adverse Events in Bladder Cancer Patients Treated With Immune Checkpoint Inhibitors: Insights From a <scp>FAERS</scp> Disproportionality Analysis

INTRODUCTION: Immune checkpoint inhibitors (ICIs) are an important treatment option in bladder cancer, but clinical trials have demonstrated that they are associated with immune-related adverse events (irAEs), such as rash, hypothyroidism, hyperthyroidism, and others. This study aimed to evaluate real-world evidence of these irAEs using the FDA Adverse Event Reporting System (FAERS). METHODS: We analyzed FAERS data through December 2024 to identify irAEs associated with atezolizumab, pembrolizumab, avelumab, and nivolumab in patients with bladder cancer. A case/non-case pharmacovigilance analysis was conducted to assess the association between ICI monotherapy and specific irAEs, including rash, pruritus, hypothyroidism, hyperthyroidism, colitis, nephritis, myocarditis, pneumonitis, and myositis. RESULTS: A total of 365 unique irAE reports were identified. Significant safety signals were observed for hyperthyroidism with atezolizumab (PRR: 3.51 [95% CI: 1.07-11.45]; ROR: 3.53 [95% CI: 1.07-11.61]; IC: 1.10 [95% CI: 0.33-1.87]), rash with pembrolizumab (PRR: 2.11 [95% CI: 1.17-3.80]; ROR: 2.14 [95% CI: 1.18-3.90]; IC: 0.44 [95% CI: 0.17-0.71]), and myositis with avelumab (PRR: 5.30 [95% CI: 1.35-20.82]; ROR: 5.47 [95% CI: 1.34-22.29]; IC: 1.95 [95% CI: 0.65-3.25]). While not reaching the threshold for statistical significance, nephritis with atezolizumab did not meet predefined signal detection criteria and should only be considered as hypothesis-generating. A similar borderline pattern was observed for hypothyroidism with avelumab. CONCLUSION: The occurrence of irAEs varies by ICI agent among bladder cancer patients. These findings underscore the importance of post-marketing surveillance in identifying real-world safety signals. Proactive management and patient education are essential to mitigate irAEs and preserve quality of life.