CTLA4 and cancer: Modulators of the immune checkpoints, in particular antibodies inhibiting CTLA4 (Ipilimumab), PD-1 (Cempilimab, Nivolumab or Pembrolizumab) or PD-L1 (Durvalumab, Avelumab or Atezolizumab) have heralded a new dawn for cancer therapy.