CTLA4 and cancer: Immune checkpoint inhibition, including antibodies against cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1), increases the therapeutic options available for metastatic lung cancer, and nowadays can be delivered as a monotherapy or a combination therapy; it also represents an alternative treatment opportunity for patients with advanced non-small cell lung cancer (NSCLC) after failure of target therapy [2,3].