EBV⁺ and MSI Gastric Cancers Harbor High PD-L1/PD-1 Expression and High CD8⁺ Intratumoral Lymphocytes.

Both EBV⁺ and MSI gastric cancers (GCs) have high lymphoid infiltration which is rare in MSS/EBV cancers. PD-L1/PD-1 interaction leads to a down-regulated immune response and it is one of the most promising targets for gastric cancer immunotherapy. PD-L1/PD-1 and CD8 expression were immunohistochemically investigated in a series of 169 FFPE GCs, including 33 EBV⁺, 59 MSI and 77 MSS/EBV cases.