CTLA4 and cancer: Oncolytic virus therapies, cancer vaccines, cytokine therapies, adoptive cell transfer therapies, and ICIs are included, and ICIs, which include inhibitors of the programmed cell death protein 1 (PD-1), programmed cell death-ligand 1 (PD-L1), and the cytotoxic T lymphocyte-associated protein 4 (CTLA-4), have been broadly used in clinical applications and contribute to prolonged survival for lung cancer patients (2–5).