CD274 and neoplasm: In this study the association between the clinical efficacy of treatment and PD-L1 expression, defined as a combined positive score (number of PD-L1 positive tumor or immune cells divided by the total number of viable tumor cells) and as a tumor proportion score (percentage of viable tumor cells with partial or complete staining for PD-L1 relative to all viable cells), was assessed in 52/104 patients.