Totally 108 AML-CR1 patients undergoing allo-HSCT were randomized into BuCy (busulfan 1.6mg/kg, q12 hours, -7 ~ -4d; cyclophosphamide 60mg/kg.d, -3 ~ -2d) or BuFlu (busulfan 1.6mg/kg, q12 hours, -5 ~ -2d; fludarabine 30mg/m2.d, -6 ~ -2d) group. Hematopoietic engraftment, regimen-related toxicity (RRT), graft-versus-host disease (GVHD), transplant related mortality (TRM), and overall survival were compared between the two groups.

All patients achieved hematopoietic reconstitution except for two patients who died of RRT during conditioning. All patients obtained complete donor chimerism by day +30 post-transplantation. The incidence of total and III-IV RRT were 94.4% and 81.5% (P = 0.038), and 16.7% and 0.0% (P = 0.002), respectively, in BuCy and BuFlu group. With a median follow up of 609 (range, 3--2130) days after transplantation, the 5-year cumulative incidence of TRM were 18.8 +/- 6.9% and 9.9 +/- 6.3% (P = 0.104); the 5-year cumulative incidence of leukemia relapse were 16.5 +/- 5.8% and 16.2 +/- 5.3% (P = 0.943); the 5-year disease-free survival and overall survival were 67.4 +/- 7.6% and 75.3 +/- 7.2% (P = 0.315), and 72.3 +/- 7.5% and 81.9 +/- 7.0% (P = 0.177), respectively in BuCy and BuFlu group.

Compared with BuCy, BuFlu as a myeloablative condition regimen was associated with lower toxicities and comparable anti-leukemic activity in AML-CR1 patients undergoing allo-HSCT.