PD-L1 expression is associated with massive lymphocyte infiltration and histology in gastric cancerâ˜

SummaryThe mechanism of carcinogenesis of gastric cancer (GC) is still unclear now. This study aimed to explore the correlations among PD-L1, Epstein-Barr virus (EBV) infection, lymphocyte infiltration, HER2 expression, HER2 gene status, histology, and other clinicopathological factors in GC. A total of 44 GC patients with massive lymphocyte infiltration (GC-MLI) and 93 GC patients without massive lymphocyte infiltration were involved in this study. Immunohistochemical analysis was used to test the expression levels of PD-L1 and HER2. Fluorescence in situ hybridization was used on HER2-positive cases with a score of 2 + to test the HER2 gene status. EBV-encoded RNA was used to test for EBV infection. In univariate analysis, PD-L1 expression was significantly associated with GC-MLI (P < .001), lower age (P = .019), EBV infection (P < .001), lower HER2 expression (P = .011), and diffuse/mixed type of histology (P = .022). EBV-encoded RNA-positive cases were significantly associated with GC-MLI (P < .001), lower age (P = .016), diffuse/mixed type of histology (P = .011), and lower HER2 expression (P = .032). In the multivariate logistic regression model, GC-MLI and the diffuse/mixed type histology were identified as 2 independent factors that affected PD-L1 expression (P < .001). Furthermore, PD-L1-positive cases have worse overall survival than do PD-L1-negative cases (P = .011). These results suggest that massive lymphocyte infiltration and the diffuse/mixed type histology of GC should be taken into consideration to select the appropriate patients for PD-L1 inhibitory treatment in the future.