The CTLA-4 blocking antibody (Ipilimumab), two PD-1 antagonists (Pembrolizumab and Nivolumab), and three PD-L1 inhibitors (Atezolizumab, Avelumab, and Durvalumab) are currently approved in specific clinical indications for immunotherapy of cancers, such as melanoma, non-small cell lung cancer, head and neck cancer, or bladder cancer. This evidence concerns the gene CTLA4 and cancer.