This is a multi-center randomized study to compare the reduced-dose of post-transplantation cyclophosphamide (PTCY) at 35mg.kg to standard dose at 50mg/kg combined with tacrolimus and post-engraftment low dose anti-thymoglobin (ATG) as graft versus host disease (GVHD) prophylaxis in patients undergoing allogeneic stem cell transplantation from alternative donor.

This is a multi-center randomized study in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) from alternative donors (9-10/10 matched unrelated donor or haplo-identical donors). The aim is to evaluate to the efficacy and feasibly of reduced-dose of PTCY at 35mg/kg as GVHD prophylaxis. Patients will be assigned to study group receiving PTCy at 35mg/kg on day +3 and +4 together with tacrolimus starting from day +5 and single dose anti-thymoglobin at 2.5mg/kg as GVHD prophylaxis or to the control group with standard dose of PTCY at 50mg/kg on day +3 and +4 with same dose of tacrolimus and ATG as the study group.

Inclusion Criteria:

1. patients undergo allo-HSCT with matched unrelated donor or haplo-identical donor;
2. normal organ function (creatinine clearance ≥ 50ml/min/1.73m2 or creatinine ≤2mg/d(or 177μmol/L); no hepatic abnormal (ALT or AST≤2.5xN; TBil≤1.5XN); Normal pulmonary function (FEV1、 FVC、DLCO≥80%); normal cardiac function (EFS ≥50%);
3. ECOG: 0-2;
4. Life expectation ≥3 months;
5. Informed consent provided.

Exclusion Criteria:

1. Pregnancies
2. active hepatitis (HBV-DNA≥1×103 copies/ml);
3. active infection require anti-biotics;
4. HIV infection