CTLA4 and cancer: Furthermore, immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 (PD-1), PD-ligand 1 (PD-L1), and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) has demonstrated to benefit cancer patients in the clinic and emerged as a standard treatment strategy in advanced non-small cell lung cancer (NSCLC) [4].