CTLA4 and lung cancer: In recent years, ICIs have revolutionized lung cancer treatment, with three main classes currently approved: PD-1 inhibitors (nivolumab, pembrolizumab, sintilimab), programmed death-ligand 1 (PD-L1) inhibitors (atezolizumab, durvalumab), and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) inhibitors (ipilimumab, tremelimumab) [17].