PDCD1 and neoplasm: Unlike other therapies, the goal of immunotherapy is to boost or restore the ability of immune cells to kill tumor cells.109 Tumor cells suppress and evade the immune system through interactions between the programmed cell death protein 1 (PD-1) of T-cells and the PD ligand 1 (PD-L1) of tumor cells.110 Two monoclonal antibodies against PD-1 (Table 3), including nivolumab111–114 and pembrolizumab,115, 116 have received FDA approval for second-line treatment against NSCLC that express PD-L1.