PDCD1 and neoplasm: Immune-checkpoint blockade (ICB) drugs such as antibodies against programmed cell death 1 (PD-1), programmed death ligand 1 (PD-L1) or cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) (respectively, anti-PD-1, anti-PD-L1 and anti-CTLA-4) aim to reinvigorate tumour-infiltrating CD8+ T cells.