Onset and Outcomes of Immune-related Adverse Events in Genitourinary Cancer Treated With Immune Checkpoint Inhibitors

Immune checkpoint inhibitors are widely used in treating metastatic urothelial carcinoma and metastatic renal cell carcinoma. However, the incidence, timing, and clinical impact of immune-related adverse events in real-world practice remain unclear. This study aimed to investigate their onset patterns and outcomes.

We retrospectively analyzed 210 patients with metastatic urothelial carcinoma (n=127) or metastatic renal cell carcinoma (n=83) treated with immune checkpoint inhibitors between 2017 and 2023 at a single academic institution. Events were graded using Common Terminology Criteria for Adverse Events version 5.0. Associations with progression-free and overall survival were assessed. We also evaluated cumulative incidence, corticosteroid or immunosuppressant use, and outcomes after rechallenge.

Immune-related adverse events occurred in 78 patients (37.1%), more frequently in metastatic renal cell carcinoma (47.0%) than in metastatic urothelial carcinoma (30.9%). Overall, grade ≥3 events occurred in 22.0% of patients, with higher incidence in renal cell carcinoma (27.7%) than in urothelial carcinoma (17.3%). In metastatic urothelial carcinoma, their presence was linked to longer survival; no difference was seen in metastatic renal cell carcinoma. Most events developed within six months; only 3.4% occurred after one year. High-dose corticosteroids were administered in 13.8% of patients, and 72.4% of them successfully completed tapering. Immunosuppressants were used in 1.4%. Eleven patients underwent rechallenge, of whom two experienced recurrence.

Immune-related adverse events showed distinct incidence and prognostic relevance between urothelial and renal cell carcinoma. These findings underscore the need for treatment-specific monitoring and provide practical insights into managing toxicities and decisions regarding immunotherapy rechallenge.