Different monoclonal antibodies clones and reagent kits as well as various equipment for IHC staining were used for the determination of PD-L1 expression on tumor and immune cells in clinical trials with various anti-PD-1 or anti-PD-L1 antibodies (Table 1) [1,2,3,4,5,6,7,8,9,10,11,12]. The gene discussed is CD274; the disease is neoplasm.