Histological Type, Cytotoxic T Cells and Macrophages in the Tumor Microenvironment Affect the PD-L1 Status of Gastric Cancer

Abstract

Gastric cancer (GC) therapies include gastrectomy and chemoradiotherapy. The tumor immune microenvironment (TME) has implications for potential immunotherapy. We analyzed the expression of PD-L1, CD8, CTLA-4 and IFN-γ in the tumor and regional lymph node (LN) of patients with GC and compared it with clinical and pathological data. Paraffin blocks were collected from 97 patients undergoing gastrectomy/lymphadenectomy for GC. Double immunohistochemistry was performed for CD8 and PD-L1 and double immunofluorescence for CTLA-4 and IFN-γ. Statistical significance was set at p p = 0.046), the density of macrophages and CD8 + T cells (p + lymphocytes in the LN (p = 0.027) and CTLA4+/IFN-γ+ in tumors and the LN (all p p = 0.008). PD-L1 expression in tumor cells correlated with CD8 + T cells and macrophages in the TME and IFN-γ expression with suppressive CTLA4+/IFNγ+ immune cells in the TME and LN.

Keywords

• gastric cancer
• tumor immune microenvironment
• PD-L1
• CTLA-4
• IFN-γ