PDCD1 and neoplasm: Recently, CIT has garnered significant interest with the approval of several immune checkpoint inhibitors (Programmed cell death protein 1, Programmed death-ligand 1 and cytotoxic T-lymphocyte-associated protein 4), cancer vaccines and adjuvants (Dendritic cell vaccines and CpG, tumour protein), cytokine therapies (Interferon alfa , IL-2) and adaptive cell-based immunotherapies (Chimeric antigen receptor T-cells, Tumour-infiltrating T-cells, Natural killer cells) [1].