S ince its first discovery 1 and initial report on the prognostic impact in patients with FMS-related tyrosine kinase 3 (FLT3)-mutated acute myeloid leukemia (AML), 2 a large amount of data has been accumulated which have helped devise the best therapeutic approach for patients with this disease. Constitutive activation of FLT3 by internal tandem duplications (ITD) occurs in approximately 20-30% of patients with cytogenetically normal (diploid) AML (CN-AML), the most frequent molecular aberration in patients with AML, while the less common mutations (7%) are those found in the tyrosine kinase domain (FLT3-TKD).3,4 The presence of FLT3-ITD mutations is widely accepted as a poor prognostic factor in CN-AML owing to its chemoresistance, high risk of relapse and short relapse-free survival (RFS), whereas the prognostic impact of FLT3-TKD mutation remains unclear. 3,[5][6][7] Although evidence from a large meta-analysis indicated that patients with either cytogenetic high-or intermediaterisk AML benefit from allogeneic hematopoietic stem cell transplantation (AHCT), 8 until recently, the role of AHCT in patients with FLT3-ITD-mutated AML remained a matter of debate, as post-transplant outcomes were inconsistent between studies.In a study by Gale et al., the outcomes of adult AML patients treated according to the United Kingdom Medical Research Council (UK MRC) protocols were analyzed. Results from the donor-versus-no donor analysis of patients with FLT3-ITD-mutated AML showed a significantly lower relapse rate in patients with a donor, but overall survival (OS) was not significantly improved when compared with the no donor group. The authors concluded that the presence of an FLT3-ITD mutation should not influence the decision to proceed to transplantation. However, in total only a small number of patients received an allograft, and only 37 of the 68 FLT3-ITD-positive patients (54%) with donors actually received an allograft in first complete remission (CR1) in this study. Moreover, this analysis may be subject to selection bias as there was no direct comparison between FLT3-ITD patients receiving allografts and those receiving chemotherapy alone. On the contrary, several more recent studies indicate that AHCT is likely the best consolidation therapy for patients with FLT3-ITD-mutated AML, and should be performed as soon as possible in CR1. [10][11][12][13] In a study by DeZern and colleagues, there was significantly better RFS of FLT3-ITDmutated AML patients treated with AHCT as compared to the non-transplant group (54 months vs. 8.6 months), 12 while a study from the MD Anderson Cancer Center, which compared post-remission treatment with consolidation chemotherapy and AHCT in 227 FLT3-mutated AML patients who achieved CR1 after induction chemotherapy, showed that AHCT reduced the risk of relapse and improved both RFS and OS regardless of NPM1 status and FLT3 allelic ratio. 10 Moreover, our group analyzed the outcomes of 200 FLT3-mutated AML patients (either ITD or TKD mutations) treated with AHCT with various donor ...