Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 0 0 2026 06 02 1 15 Lianxing Zhang Department of Digestive Oncology, Gansu Provincial Cancer Hospital, Lanzhou, Gansu, China Xia Han Department of Digestive Oncology, Gansu Provincial Cancer Hospital, Lanzhou, Gansu, China Yue Wang Department of Digestive Oncology, Gansu Provincial Cancer Hospital, Lanzhou, Gansu, China Yanrong Li Department of Digestive Oncology, Gansu Provincial Cancer Hospital, Lanzhou, Gansu, China Jia Wang Department of Digestive Oncology, Gansu Provincial Cancer Hospital, Lanzhou, Gansu, China 2025 12 26 2026 01 28 While immune checkpoint inhibitors (ICIs) are a key treatment for advanced gastric cancer (AGC), the prognostic significance of their associated immune-related adverse events (irAEs) remains unclear. This real-world study aims to evaluate irAE incidence and impact on clinical outcomes. This retrospective study consecutively enrolled 156 patients with AGC who received ICI therapy and completed follow-up between January 2021 and June 2023. Baseline characteristics, treatment regimens, irAE occurrence, and survival data were collected. The prognostic impact of irAEs was assessed by objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). A total of 156 patients were included, of whom 76 (48.72%) developed irAEs. The most  common types were endocrine, cutaneous, and gastrointestinal toxicities, mostly of grades 1-2. Multivariate logistic regression analysis identified age≥70 years (OR=2.615), BMI ≥ 25 kg/m² (OR=5.791), prior chemotherapy (OR=4.954), prior targeted therapy (OR=5.532), ICI combined with chemotherapy (OR=5.456), ICI combined with targeted therapy (OR=2.850), and a history of smoking (OR=3.224) as independent predictors of irAEs. Compared with the non-irAEs group, the irAEs group showed superior clinical efficacy, with a significantly higher ORR (38.16% vs. 20.00%) and DCR (80.26% vs. 66.25%). Kaplan-Meier survival analysis revealed a significant association between the occurrence of irAEs and prolonged survival, with the irAEs group showing superior median PFS (8.0 vs. 5.0 months) and OS (15.0 vs. 10.0 months) compared to the non-irAEs group. For AGC patients receiving ICI therapy, the development of irAEs correlates significantly with improved survival, serving as a potential biomarker of clinical benefit. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4722 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4722/2354