2.3 Conditioning regimen and stem cell collection
All patients received a myeloablative conditioning regimen (MAC) without in vitro T-cell depletion. The conditioning regimens used in our center were based on BU and total body irradiation (TBI). For patients who received haploidentical HSCT, the conditioning regimen was modified to include the following: BUCY+ATG (thymoglobulin) consisting of cytarabine (4 g/m2 per day in haploidentical HSCT) intravenously on days -10 to -9; busulfan (3.2 mg/kg per day, intravenously on days -8 to -6); cyclophosphamide (CY, 1.8 g/m2 per day) intravenously on days -5 to -4; Me-CCNU (250 mg/m2), orally once on day -3; and thymoglobulin (ATG, Sang Stat, Lyon, France; 2.5 mg/kg per day) intravenously for 4 consecutive days from days -5 to -2. Patients undergoing HLA-matched sibling donor HSCT received hydroxycarbamide (80 mg/kg) orally on day -10 and a lower dose of cytarabine (2 g/m2 per day) on day -9, but otherwise, these patients followed an identical regimen to haploidentical patients, without ATG. The TBI-based conditioning regimen was composed of the following: TBI (770 cGy for a single dose) on days -6 and cyclophosphamide (CY, 1.8 g/m2 per day) intravenously on days -5 to -4; and Me-CCNU (250 mg/m2), orally once on day -3. ATG was used for patients who received haplo-HSCT, and the dosage and time were consistent with the above description. All subjects received fresh granulocyte colony-stimulating factor (G-CSF)-mobilized bone marrow (BM) and peripheral blood cells. Patients also received prophylactic drugs to prevent infection by fungi and viruses.