Cytotoxic T‐lymphocyte‐associated protein 4 in gastric cancer: Prognosis and association with PD‐L1 expression

Background Cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4) is one of the most studied immune checkpoint in gastric cancer (GC). However, the prognostic role of CTLA‐4 expression in GC is poorly described. This study aimed to evaluate CTLA‐4 expression in GC and its impact on survival, including patients treated with standard platinum‐based chemotherapy (CMT), and association with PD‐L1 expression. Methods All GC patients who underwent D2‐gastrectomy were investigated retrospectively. Tumor samples were examined for CTLA‐4 and PD‐L1 by immunohistochemistry. Tumor‐infiltrating inflammatory cells, including CD4 + and CD8 + , were also examined. Results Among the 284 GC patients included, 159 (56%) were CTLA‐4 positive and the remaining 125 (44%) were classified as negative. CTLA‐4 positive GC was associated with increased inflammatory cell infiltration (p