DPH1 and acute myeloid leukemia: Resistance to tagraxofusp is mediated by downregulation of DPH1, the enzyme that converts histidine 715 on eEF2 to diphthamide, the direct target of ADP ribosylation by diphtheria toxin, an effect reverted by exposure to azacytidine (44), providing the preclinical rationale for the development of the combination of tagraxofusp with azacytidine in patients with R/R AML or in treatment-naive AML not eligible for standard induction therapy (NCT 03113643).