CD274 and neoplasm: However, other studies have shown conflicting reports on rates of PD-L1 overexpression, potentially due in part to differences in how PD-L1 expression is measured and defined, with one study reporting 0% (0/18) expression (≥1% on tumor cells, SP142), and another reporting 50% (7/14) expression (>1% on immune cells and >+ by IHC, SP263) (25, 33).