Pembrolizumab, an anti-PD-1 agent, is a highly selective humanised IgG4 monoclonal antibody that blocks the interaction between PD-1 (programmed cell death 1) on T cells and its ligands, PD-L1 and PD-L2 (programmed cell death ligand 2), to functionally hamper the immune escape of tumour cells [2, 3]. This evidence concerns the gene PDCD1 and neoplasm.