Treatment patterns and clinical outcomes of metastatic gastric cancer: Real-world evidence from retrospective electronic medical records data.

329 Background: Five-year survival of patients with metastatic gastric cancer (mGC) is poor. Tumor characteristics, timing of diagnosis, and treatment patterns differ between patients from Eastern and Western regions. Therefore, we aimed to evaluate treatment patterns and outcomes of patients with mGC in South Korea. Methods: This retrospective study aimed to analyze electronic medical records. Treatment patterns were evaluated in 2,229 patients, and clinical outcomes were assessed in 2,083 patients. Results: The median age of the included patients was 60 (range, 18–92) years (62.8%, male; 95.5% had ECOG of 0–1). Among tested patients, HER2-positivity, MSI-H/dMMR, and PD-L1 22C3 Combine Positive Score ≥1 rates were 16.0%, 4.7%, and 49.1%, respectively. Of the 2,353 patients, 94.7%, 68.0%, and 52.9% received first-line (1L), second-line (2L), third-line (3L) therapy, respectively. Platinum doublets were used for 1L (61.3%); paclitaxel plus ramucirumab, 2L (50.6%); and irinotecan-based therapy, 3L (51.1%). The median overall survival (OS) was 3.8 and 16.3 months in the untreated and treated patients, respectively. Overall, HER2-positive patients treated with HER-2 targeted agent had a longer OS (19.1 months), and those treated with combined HER2-targeted plus immune checkpoint inhibitor (ICI) therapy (23.1 months) had the longest OS. In HER2-negative patients, OS was 15.7 months with chemotherapy, and 17.6 months with combined chemotherapy plus ICI. No survival differences were found between patients treated with oxaliplatin and cisplatin in 1L, irinotecan and taxane in 2L/3L, and across 2L to 3L sequences. Conclusions: Our findings support the benefits of multiline personalized treatments in mGC.