Conditioning regimen with melphalan-busulfan and fludarabine (MBF) achieved low relapse rate in patients with acute myeloid leukemia (AML) and myelodysplasia syndrome (MDS). In our previous retrospective study, we demonstrated that melphalan dose at 100 or 140mg/m2 had similar incidence of relapse but it might had lower toxicities. In this prospective randomize study, we aim to compare the transplantation outcome in adult patients with AML/MDS receiving either MBF with 100 or 140 mg/m2 melphalan.

Intensity of conditioning regimen plays a important role in allogeneic stem cell transplantation (allo-HSCT) for patents with AML and MDS. IN our previous prospective study, we demonstrated that condoning regimen of dual alkylating agents with melphalan-busulfan and fludarabine (MBF) achieved a very low relapse rate (~6%) in patients with acute myeloid leukemia (AML) and myelodysplasia syndrome (MDS). In that study, adult patients received melphalan 140mg/m2 while patients >=60 or with high transplantation risk in terms of HCT-CI received reduced dose of melphalan (100mg/m2). Overall, it was shown that 100 or 140mg/m2 melphalan had similar incidence of relapse while the 100mg/m2 melphalan presented lower incidence of toxicities.In this prospective randomize study, we aim to compare the transplantation toxicities and outcomes in young adults (18~55) with AML/MDS receiving either 100 or 140 mg/m2 melphalan as conditioning regimen.

Inclusion Criteria:

• Patients with AML in first remission
• Patients with MDS with bone marrow blast >5% but remain less than 20% before transplantation
• Donor available: HLA matched sibling donor, 9~10/10 matched unrelated donor or haplo-identical donor
• Inform consent provided

Exclusion Criteria:

• Patients with active infection (bacteria, fungal or viral)
• Patients with abnormal liver, renal and cardiac function