PDCD1 and neoplasm: Antibodies (Abs) targeting regulatory immune checkpoint molecules (e.g., PD1, PDL1, CTLA4) on lymphocytes, mainly T-cells, and antigen-presenting cells including dendritic cells (DCs) and macrophages, reinforce the host’s anti-tumor response and reshape the immunosuppressive tumor tissue microenvironment into a permissive mode towards combination therapies including small molecules and adoptive cell transfer (e.g., CAR-T cells [3]).