LAG3 in gastric cancer: it’s complicated

PURPOSE: Lymphocyte activation gene 3 (LAG3) is thought to contribute to T cell exhaustion within the tumor microenvironment of solid tumors. This study aimed to analyze the spatial distribution of LAG3 + cells in relation to clinicopathological and survival data in a large set of 580 primary resected and neoadjuvantly treated gastric cancers (GC). METHODS: LAG3 expression was evaluated in tumor center and invasive margin using immunohistochemistry and whole-slide digital image analysis. Cases were divided into LAG3-low and LAG3-high expression groups based on (1) median LAG3 + cell density, (2) cut-off values adapted to cancer-specific survival using Cutoff Finder application. RESULTS: Significant differences in spatial distribution of LAG3 + cells were observed in primarily resected GC, but not in neoadjuvantly treated GC. LAG3 + cell density showed evident prognostic value at following cut-offs: in primarily resected GC, 21.45 cells/mm(2) in tumor center (17.9 vs. 10.1 months, p = 0.008) and 208.50 cells/mm(2) in invasive margin (33.8 vs. 14.7 months, p = 0.006); and in neoadjuvantly treated GC, 12.62 cells/mm(2) (27.3 vs. 13.2 months, p = 0.003) and 123.00 cells/mm(2) (28.0 vs. 22.4 months, p = 0.136), respectively. Significant associations were found between LAG3 + cell distribution patterns and various clinicopathological factors in both cohorts. In neoadjuvantly treated GC, LAG3 + immune cell density was found to be an independent prognostic factor of survival (HR = 0.312, 95% CI 0.162–0.599, p < 0.001). CONCLUSION: In this study, a higher density of LAG3 + cells was associated with favorable prognosis. Current results support the need for extended analysis of LAG3. Differences in the distribution of LAG3 + cells should be considered, as they could influence clinical outcomes and treatment responses. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00432-023-04954-1.