High expressions of PD-1/PD-L1 have been proposed as cancer markers to predict response to treatment to monoclonal anti PD-1/PD-L1 checkpoint inhibitors, and expression of PD-1 and PD-L1 have been found in cancer cells and tumor infiltrating lymphocytes in both canine and human melanoma [30,31]. The gene discussed is CD274; the disease is neoplasm.