CTLA4 and lung cancer: Immune checkpoint inhibitors, mainly drugs targeting the programmed cell death 1(PD-1)/programmed cell death ligand 1 (PD-L1) and cytotoxic T-lymphocyte antigen4 (CTLA4) pathways, represent a remarkable advance in lung cancer treatment.Immune checkpoint inhibitors targeting PD-1 and PD-L1 are approved for thetreatment of patients with non-small-cell lung cancer, with impressive clinicalactivity and durable responses in some patients.