Development of immune-related adverse events is associated with improved survival outcomes in cancer patients receiving immune checkpoint inhibitors.

Immune checkpoint inhibitors (ICIs) have become the standard-of-care in various cancer types. However, treatment with ICIs occasionally cause immune-related adverse events (irAEs). This study assessed the incidence and clinical features of irAEs and examined their association with treatment outcomes in patients with solid tumors receiving ICIs. We conducted a retrospective cohort study including 385 patients with histologically confirmed solid tumors treated with ICIs. Patients were categorized according to the occurrence of irAEs. Baseline clinicopathological characteristics, irAE patterns, management strategies, and survival outcomes were analysed. To minimize immortal time bias, landmark analyses at three months were performed. Multivariable Cox regression models were used to evaluate the association between irAEs occurring within the first three months of treatment and subsequent survival outcomes after adjustment for clinically relevant confounders. Among 385 patients, 181 (47%) developed at least one irAE during ICI treatment. The most frequently observed irAEs included transaminitis, thyroiditis, pneumonitis, rash, and colitis. Patients who developed irAEs had significantly improved survival outcomes compared with those without irAEs. In landmark Kaplan-Meier analyses, patients who developed irAEs during follow-up had significantly improved OS and PFS compared with those who did not. In landmark-adjusted multivariable analysis, irAEs was associated with improved OS (HR 0.673, 95% CI 0.453-1.00; P = 0.0498), whereas the association with PFS was not statistically significant (HR 0.851, 95% CI 0.630-1.149; P = 0.2916). A baseline neutrophil-to-lymphocyte ratio (NLR) <3 was associated with favourable survival outcomes. Most irAEs were managed with corticosteroids and temporary treatment interruption. Development of irAEs was associated with improved survival outcomes in patients with solid tumors treated with ICIs. These findings support the hypothesis that irAEs was associated with enhanced anti-tumor immune activity. Real-world characterization of irAEs and their management may help optimize patient monitoring and treatment strategies during immunotherapy.