Donor-specific Allogeneic Hematopoietic Cell Transplantation for Acute Lymphoblastic Leukemia (ALL)

"\[ alloHCT arm \] Bu-Cy conditioning; Busulfan (Bu) 3.2 mg/kg\*/day iv daily on days -7 and -4. Cyclophosphamide (Cy) 60 mg/kg\* in D5W 200 mL iv over 1-2 hours daily on days -3 and -2.~BuFluATG conditioning; Bu 3.2 mg/kg\*/day iv daily on days -7 and -6. Fludarabine (Flu) 30 mg/m2/day in D5W 100 ml iv over 30 minutes starting at 4 pm daily on days -7, -6, -5, -4, -3, and -2.~Anti-thymocyte globulin (ATG, Thymoglobulin, Genzyme Transplant, Cambridge, MA, USA) 1.5 mg/kg/day (for HLA-matched sibling HCT) or 3.0 mg/kg/day (for HLA-matched unrelated donor HCT or HLA-mismatched familial donor HCT) in N/S 500-800 ml (less than 4 mg/ml) iv over 4 hours starting at 8 am daily on days , -3, -2 and -1."