CTLA4 and cancer: Liu et al. have recently used partial Treg depletion to sensitize mice for irAE.36 While this model recapitulated some pathological features of irAE, it is noted that Ipilimumab systematically expands rather than depletes Treg cells in human cancer patients,37 a feature we observed when we used Ipilimumab in our human CTLA4 knock-in mice (data not shown).