Secondly, immune-checkpoint blockade, especially via inhibition of the potent immunoevasive effects of the Programmed Death-1 (PD-1) / Programmed Death – Ligand 1 (PD-L1) axis, has become a powerful tool of tumor immunotherapy, with variable responses in diverse cancer types [18, 19, 20] and partially conflicting results regarding the predictive value of immunohistochemical PD-L1 expression [18]. This evidence concerns the gene CD274 and cancer.