Outcomes and prognosis of haploidentical haematopoietic stem cell transplantation in children with FLT3-ITD mutated acute myeloid leukaemia

Abstract The presence of internal tandem duplication mutations in the FMS-like tyrosine kinase 3 receptor ( FLT3-ITD ) is a poor prognostic predictor in paediatric patients with acute myeloid leukaemia (AML). We evaluated the treatment outcomes and prognostic factors of 45 paediatric patients with FLT3-ITD AML who achieved complete remission before haploidentical haematopoietic stem cell transplantation (haplo-HSCT) at our institution from 2012 to 2021. Among the 45 patients, the overall survival (OS), event‑free survival (EFS), and cumulative incidence of relapse (CIR) rates were 74.9%±6.6%, 64.1%±7.2%, and 31.4%±7.1%, respectively, with 48.8 months of median follow-up. Univariate and multivariate analyses associated positive minimal residual disease (MRD) at pre-HSCT , MRD by flow cytometry (FCM)≥0.1% after two cycles induction and time from diagnosis to HSCT more than 24 months with inferior long-term survival. The 4-year CIR of grade II–IV acute graft-versus-host (GVHD) and chronic GVHD after transplantation were 53.3% ± 7.6% and 35.7% ± 9.8%, respectively. In conclusion, haplo-HSCT may be a feasible strategy for paediatric patients with FLT3-ITD AML. MRD status at pre-HSCT, MRD by FCM after two cycles induction and the time from diagnosis to HSCT affect patient outcomes.