CD274 and neoplasm: Most NSCLC tumors do not express PD-L1 at high levels, although reported levels vary; [20, 36, 37] only ~20 % of NSCLC tumors were reported to show PD-L1 expression in 5 % or more of tumor cells obtained with three different IHC assays (using different PD-L1 antibody clones; E1L3N, 22C3, and 5H1) [20, 38, 39].