CTLA4 and cancer: Since the registration of ipilimumab, an anti-cytotoxic T lymphocyte-associated antigen-4 (anti-CTLA-4) monoclonal antibody, in 2011 and the registration of monoclonal antibodies against programmed death-1 (PD-1) (e.g., pembrolizumab, nivolumab) and PD-L1 (e.g., atezolizumab) in 2014, survival rates have improved tremendously among patients with an advanced-stage cancer [2].