CTLA4 and cancer: Modulators of immune checkpoints, namely antibodies targeting PD-1 (Pembrolizumab, Nivolumab and Cempilimab), PD-L1 (Atezolizumab, Avelumab or Durvalumab) or CTLA4 (Ipilimumab) are at the vanguard of a reinvigorated approach to harness the immune system to kill human cancers [1].