PDCD1 and cancer: Varieties of cancer cells have been detected through PD-L1 expression including melanoma, multiple myeloma, leukemia, glioblastoma as well as gastric, renal cell, bladder, hepatocellular, cutaneous, breast and NSCLC (Non-Small Cell Lung Cancer) [26,27,28,29,30,31,32,33], whereas PD-1 have been highly detected on tumor-infiltrating lymphocytes (TILs) [34,35].