CD274 and gastric cancer: PD-L1 expression remains the commonly explored biomarker for predicting the response to anti-PD1 therapy in several cancers including lung cancer (28), melanoma(29), and gastric cancer (30), whereas biomarker role of PD-L1 expression was disputable when analyzing the association between PD-L1 expression and the response to a PD-1 blockade (31).