This is a prospective, single-center, observational study to evaluate the efficacy and safety of salvage haploidentical allogeneic hematopoietic stem cell transplantation (haplo-HSCT) combined with post-transplant relapse prevention strategies in patients with relapsed/refractory acute myeloid leukemia (R/R AML). Eligible patients are adults aged 18-65 years with active AML (bone marrow blasts \>5% or extramedullary disease) and HCT-CI score ≤5. All patients will receive a uniform conditioning regimen consisting of fludarabine, busulfan, and MECCNU, with addition of targeted agents (such as sorafenib, midostaurin, or venetoclax) according to mutation status. Graft-versus-host disease (GVHD) prophylaxis includes reduced-dose ATG (6 mg/kg), FK506, MMF, and basiliximab. Post-transplant maintenance with targeted therapy or azacitidine and prophylactic donor lymphocyte infusion (DLI) will be administered to reduce relapse risk. The primary endpoints are cumulative incidence of relapse (CIR), overall survival (OS), and progression-free survival (PFS). Secondary endpoints include incidence of acute and chronic GVHD, CMV/EBV reactivation, non-relapse mortality (NRM), and GVHD-free, relapse-free survival. Patients will be followed for 24 months after transplantation. This study aims to explore an optimized transplant strategy to improve long-term survival in this high-risk population.
Study Type
OBSERVATIONAL
Enrollment
40
Salvage haploidentical allogeneic hematopoietic stem cell transplantation using a conditioning regimen of Fludarabine (120-180 mg/m²), Busulfan (3-4 mg/kg), and MECCNU 250 mg/m² (intensity adjusted based on prognostic index). Targeted agents (sorafenib, midostaurin, or venetoclax) are added according to genetic mutations (e.g., FLT3) until stem cell infusion. GVHD prophylaxis includes ATG 6 mg/kg, tacrolimus (FK506), mycophenolate mofetil (MMF), and basiliximab on day +4. No MTX or post-transplant cyclophosphamide (PTCY) is used. Immunosuppressants are tapered within 100 days if no significant GVHD.
Starting from approximately day +30 after transplantation, patients receive mutation-guided targeted therapy (sorafenib 200 mg daily for FLT3/ITD mutation) or azacitidine 75 mg/m² on days 1-3. Maintenance therapy aims to reduce the risk of relapse.
Cumulative Incidence of Relapse (CIR)
Time frame: Up to 24 months post-transplantation
Overall Survival (OS)
Time frame: Up to 24 months post-transplantation
Incidence of Acute GVHD (aGVHD)
Time frame: Within 100 days post-transplantation
Incidence of Chronic GVHD (cGVHD)
Time frame: Up to 24 months post-transplantation
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