CD274 and neoplasm: Importantly, enrollment was stratified by PD-L1 expression using a novel IHC assay (Ventana SP142, Table 3) in which PD-L1 positivity was categorized according to the expressing cell type (tumor cell [TC] or immune cell [IC]) and then scored along a gradient (<1 % [TC0 or IC0], 1–4 % [TC1 or IC1], 5–49 % [TC2 or IC2], and ≥50 % (TC3 or IC3]).