CD274 and neoplasm: The FDA approved PD-L1 test is performed with a device (PD-L1 IHC 22C3 PharmDx assay) that uses two parameters; Tumor Proportion Score (TPS), which is the percentage of PD-L1 positive tumor cells in relation to viable tumor cells within the sample, and Combined Proportion Score (CPS), which identifies all PD-L1 positive cells in the sample including tumor cells, lymphocytes, and macrophages by membrane staining.