CTLA4 and non-small cell lung carcinoma: There are other FDA-approved checkpoint inhibitors, such as: ipilimumab (Yervoy®) in advanced NSCLC, which has as its mechanism of action the blockade of CTLA-4, which prevents the negative regulation of T-lymphocyte activation, leading to potentiation of lymphocyte activation and, consequently, decreased tolerance to cancer antigens [47].