CTLA4 and lung cancer: Although it has been reported that ICIs including the programmed death-ligand 1 (PD-L1) and programmed death-1 (PD-1) and also cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors could significantly improve the survival among advanced lung cancer patients overall, there is still a proportion of lung cancer patients who do not respond well to immunotherapy [5,6].