Expression of Programmed Death Ligand1 (PD-L1) in Gastric Carcinoma (Histopathological and Immunohistochemical Study)

OBJECTIVES: To evaluate immunohistochemical expression of PD-L1 in cases of gastric adenocarcinoma. To correlate PD-L1 immuno-histochemical expression with other available clinico-pathological parameters such as age, sex, grade, stage, lymph node (L.N) metastasis and others. MATERIAL AND METHODS: The present retrospective study retrieved the data and archived paraffin blocks of 60 cases of Gastric carcinoma. Immunohistochemical evaluation was done to assess the expressions of PD-L1 in the tumor cells (TC), tumor infiltrated lymphocytes (TILs) and combined positive score (CPS). RESULTS: TC PD-L1 expression was detected in 56.7% of cases, TILs PD-L1 expression was detected in 53.3 % of cases and CPS PD-L1 expression was detected in 63.3% of case, with no statistically significant correlation with clinico-pathological parameters except TILs PD-L1 expression showed statistically significant correlation with positive TILs (P value ˂0.019). CONCLUSION: Our findings supported the expression of PD-L1 by TC, TILs, and CPS in gastric cancer, with increased expression in a subpopulation of TILs rich in PD-L1 identifying them as potential targets for PD-1/PD-L1 therapy.