PDCD1 and non-small cell lung carcinoma: Programmed cell death 1 (PD-1) is a receptor expressed on the surface of activated T cells;7 it binds to its ligands programmed cell death ligand-1 (PD-L1) and PD-L2, causing downregulation of the activated T cells.8 Expression of PD-L1 in NSCLC generates an immunosuppressive tumour microenvironment and promotes tumour immune escape, thus leading to poor prognosis of the disease.9 Nivolumab is a fully human IgG4 anti-PD-1 blocking monoclonal antibody approved for the treatment of NSCLC.