Objective: To investigate the clinical significance of IL-10 þ tumor-associated macrophages (TAMs) in gastric cancer. Background: Due to the plasticity and diversity of TAMs, it is necessary to phenotypically and functionally classify subsets of TAMs to better understand the critical role of TAMs in cancer progression. TAMs expressing interleukin-10 (IL-10) have been found to facilitate immune evasion in many malignancies, but the role of IL-10 þ TAMs in gastric cancer remains obscure. Methods: Four hundred and sixty-eight tumor tissue microarray specimens, 52 fresh tumor tissue samples of gastric cancer patients from Zhongshan Hospital, and data of 298 gastric cancer patients from the Cancer Genome Atlas (TCGA) were analyzed. IL-10 þ TAM level and immune contexture were examined by CIBERSORT, immunohistochemistry, and flow cytometry. Clinical outcomes were analyzed by Kaplan-Meier curves and Cox model. Results: Gastric cancer patients with high IL-10 þ TAM infiltration exhibited poor prognosis and inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy. IL-10 þ TAM infiltration yielded an immunoevasive tumor microenvironment featured by regulatory T cell infiltration and CD8 þ T cell dysfunction. The combinational analysis of IL-10 þ TAM and CD8 þ T cell infiltration stratified patients into distinct risk groups with different clinical outcomes. Moreover, IL-10 þ TAM infiltration was correlated with tumor-intrinsic characteristics including EBV status, PD-L1 expression, and genome stability in gastric cancer. Conclusions: This study revealed that IL-10 þ TAMs might drive an immunoevasive microenvironment and determine poor prognosis and inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy,indicating IL-10 þ TAMs could be applied as a potential target for immunotherapeutic approach in gastric cancer.

BACKGROUND: Intratumoural CD103 + CD8 + T cells have been linked to prolonged survival in several malignancies. However, the clinical significance of CD103 + CD8 + T cells in gastric cancer remains unexplored. METHODS: Gastric cancer tissues from Zhongshan Hospital and data from Gene Expression Omnibus were obtained and analysed. Immunohistochemistry and flow cytometry were performed to detect the number and phenotypical characteristics of CD103 + CD8 + T cells. The effect of programmed cell death protein-1 (PD-1) blockade on CD103 + CD8 + T cells was evaluated with the use of an in vitro study based on fresh tumour tissues. RESULTS: CD103 + CD8 + T cells predicted superior overall survival and provided better prognostic power than total CD8 + T cells in gastric cancer. Patients with high CD103 + CD8 + T cell infiltration also gained more benefit from adjuvant chemotherapy. Flow cytometry analysis showed that CD103 + CD8 + T cells exerted superior anti-tumour effects with stronger retention capacity and cytotoxicity. Moreover, an in vitro study showed that CD103 + CD8 + T cells were more functionally restored after PD-1 blockade than CD103 -CD8 + T cells. CONCLUSIONS: CD103 + CD8 + T cells might be a useful marker to predict prognosis and therapeutic efficacy for gastric cancer patients. Efforts to increase intratumoural CD103 + CD8 + T cell frequency might be a novel therapeutic strategy in gastric cancer.

Studies that examined an association between CD8+T and prognosis in gastric cancer are inconsistent, and a distinct population of CXCR5+CD8+T associated with better overall survival has been reported among various malignancies. Here, we show that the abundance of intratumoral CXCR5+CD8+T cells is associated with better overall survival in patients with gastric cancer. Patients with TNM II + III gastric cancer with higher intratumoral CXCR5+CD8+T cell infiltration are more likely to benefit from adjuvant chemotherapy. Microsatellite-unstable and Epstein–Barr virus positive tumors are enriched with CXCR5+CD8+T cells. Gastric cancer infiltrating CXCR5+CD8+T cells represent a specific subtype of stem-like CD8+T with effector memory feature. Identification of the clinical significance and phenotype of gastric cancer infiltrating CXCR5+CD8+T provides a roadmap for patient stratification and trials of targeted therapies.