Immune‐Related Adverse Events in Bladder Cancer Patients Treated With Immune Checkpoint Inhibitors: Insights From a FAERS 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.