Expression of PD-L1, indoleamine 2,3-dioxygenase and the immune microenvironment in gastric adenocarcinoma.

PD-L1 is expressed in a large proportion of gastric carcinomas, suggesting that therapy targeting this pathway could be relevant to many patients. PD-L1 expression and MMR-deficiency are associated with increased TILs and larger tumour size, emphasising their role in tumour biology. Higher stromal IDO expression is associated with better prognosis. Finally, we observed that immune modulators WARS and GBP5 are expressed highly in gastric adenocarcinomas, suggesting an important role in tumour pathobiology.