CTLA4 and cancer: Blocking these interactions with monoclonal antibodies (Abs) targeting PD-1 (e.g., nivolumab, pembrolizumab), PD-L1 (e.g., atezolizumab, avelumab), CTLA-4 (e.g., ipilimumab), and more recently, Lymphocyte Activation Gene-3 (LAG-3) (e.g., relatlimab) has transformed cancer treatment (3, 4).