PD-L1 expression in gastric carcinoma – a biomarker for immunotherapy

Introduction and Aim: Immunotherapy is now being widely used for targeted therapy in several cancers. The PD-1/ PD-L1 (programmed cell death receptor/programmed cell death ligand) axis inhibits the expansion of tumour specific T cells and prevents the immune response against tumours. PD-L1 expression is seen in many cancers including gastric carcinomas and anti PDL1 antibodies are being used to produce tumour regression. This study was done to evaluate PD-L1 expression in gastric carcinomas and correlate this with the different histological types, grades and stages of these tumours Materials and Methods: In this study, 50 cases of gastric adenocarcinoma were analysed for PD-L1 expression using immunohistochemistry. PD-L1 expression was correlated with histopathological factors including histological type, differentiation, grade and stage using statistical methods. Results: A positive PD-L1 expression was observed in 52% of the cases. A positive correlation between PD-L1 positivity and tumour depth to which the tumour was invading the stomach was observed. No correlation was noted with expression of PD-L1 and histological type, differentiation, histological grade and presence/absence of nodal metastasis. Conclusion: PD-L1 expression was seen in more than half of the patients in our study. Hence it is suggested that anti PD-L1 inhibitors can be used as an adjunct in the treatment of gastric cancers, especially those with a greater depth of invasion.