CTLA4 and lung cancer: Over the past few years, the immune checkpoint inhibitors (ICIs) that target programmed cell death receptor-1 (PD-1), programmed cell death-ligand 1 (PDL1), or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) have shown encouraging efficacy in a variety of tumor types such as lung cancer, melanoma, and liver cancer [1].