CTLA4 and acute myeloid leukemia: Because of the low mutational burden of AML and the correspondingly low frequency of AML-reactive T cells,427 CAR-T cell combinations with checkpoint inhibitors (e.g., anti-PD-1 or anti-CTLA-4 antibodies) might be an interesting future strategy428,429 as it may also overcome T cell exhaustion and enhance CAR-T cell efficacy.