PDCD1 and neoplasm: Therefore, in recent years, different types of immune checkpoint inhibitors, consisting of monoclonal antibodies targeting CTLA-4 or PD-1 on T-cell or programmed cell death ligand 1 (PD-L1) on tumor cells, were successfully tested in several tumors (Figure 1) and changed clinical practice, given the improvement in patients’ outcomes [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36].