MAC vs RIC for Transplantation in FLT3-ITD-Mutated AML Guided by UHS-NGS MRD ( FLT3 - MAC vs RIC )

This is a multicenter, open-label, 1:1 randomized non-inferiority trial with stratification. The study will enroll patients aged 18-60 years with FLT3-ITD-mutated acute myeloid leukemia (AML) who are in first complete remission (CR1) and have no detectable FLT3-ITD measurable residual disease (MRD) by polymerase chain reaction-next-generation sequencing (PCR-NGS) before allogeneic hematopoietic stem cell transplantation (allo-HSCT). Eligible patients will be randomly assigned to receive either reduced-intensity conditioning (RIC) or myeloablative conditioning (MAC) before allo-HSCT. All patients will receive FLT3 inhibitor maintenance therapy after transplantation. The primary objective is to determine whether RIC is non-inferior to MAC in terms of 2-year relapse-free survival (RFS), defined as the time from transplantation to relapse or death from any cause. Secondary objectives include comparisons of overall survival (OS), non-relapse mortality (NRM), cumulative incidence of relapse, and graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) between the two conditioning groups.

Inclusion Criteria: 1. Age between 18 to 60 years, any gender 2. Diagnosis of AML according to WHO criteria 3. Presence of FLT3-ITD mutation at diagnosis 4. In first complete remission 5. Planned first allogeneic hematopoietic stem cell transplantation using peripheral blood stem cells 6. Planned post-transplant maintenance therapy with a FLT3 inhibitor (including sorafenib or gilteritinib) 7. FLT3-ITD UHS-NGS MRD \< 0.001% at 14 to 28 days prior to transplantation 8. Completion of routine pre-transplant assessments; in the investigator's judgment, the patient is able to complete the conditioning regimen, stem cell infusion, and study follow-up as planned; 9. HCT-CI score of 0 to 2; in the investigator's judgment, the patient is eligible for either MAC or RIC conditioning intensity 10. ECOG performance status at 0 to 2 11. Estimated survival time ≥ 6 months 12. Major organ function meets the following requirements: ALT and AST ≤2.5 × ULN; Total bilirubin ≤1.5 × ULN; subjects with Gilbert syndrome or elevated indirect bilirubin due to documented inactive hemolysis may be enrolled at the investigator's discretion; eGFR ≥30 mL/min/1.73 m², and not receiving maintenance dialysis; LVEF ≥50%, or cardiac function status determined by the investigator to be adequate to tolerate the study treatment; No requirement for high-flow oxygen therapy or mechanical ventilation support at rest 13. Blood pressure is well-controlled; systolic blood pressure \