FLT3 and acute myeloid leukemia: The magnitude of efficacy of HDC/IL-2 in AML patients with normal karyotype, in particular in patients <60 years, suggests that the treatment effect is present within the groups of NPM1- and/or FLT3-ITD-mutated AML, as these mutations account for >75% of all normal karyotype AML.12 The results of the phase IV trial argue against the possibility that HDC/IL-2 is beneficial in patients with normal karyotype AML carrying FLT3-ITD-mutations, thus raising the possibility that HDC/IL-2 may be primarily efficacious in NPM1-mutated AML.