Immunotherapy for advanced gastric cancer: Experience from Uzbekistan.

e23352 Background: Gastric cancer is a major cause of cancer-related mortality worldwide and remains highly prevalent in Central Asia, including Uzbekistan. Perioperative FLOT chemotherapy is the current standard of care; however, its efficacy is limited in molecular subgroups such as microsatellite instability–high (MSI-H) tumors. Immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway have shown promising results in biomarker-selected patients. Methods: A real-world study was conducted at the Republican Specialized Scientific and Practical Medical Center of Oncology and Radiology between 2021 and 2025. Patients with locally advanced gastric cancer underwent routine MSI testing. MSI-H patients received either standard perioperative FLOT chemotherapy or FLOT combined with pembrolizumab. The primary endpoints were major pathological response (MPR), conversion from initially inoperable to operable disease, 6-month disease-free survival (DFS), and overall survival (OS). Results: Chemoimmunotherapy demonstrated superior outcomes compared with chemotherapy alone. Major pathological response was achieved in 60% of patients versus 12.5%. Conversion to operable status occurred in 75% versus 25% of cases. Six-month DFS was 95% in the chemoimmunotherapy group compared with 58% in the chemotherapy group. Median overall survival was not reached in the chemoimmunotherapy group, whereas it was 14.2 months with chemotherapy alone. Conclusions: Chemoimmunotherapy demonstrated superior outcomes compared with chemotherapy alone. Major pathological response was achieved in 60% of patients versus 12.5%. Conversion to operable status occurred in 75% versus 25% of cases. Six-month DFS was 95% in the chemoimmunotherapy group compared with 58% in the chemotherapy group. Median overall survival was not reached in the chemoimmunotherapy group, whereas it was 14.2 months with chemotherapy alone.