Post-transplantation cyclophosphamide (PTCY) is considered as major graft versus host disease (GVHD) prophylaxis. In our previous study, the investigators demonstrated that the standard dose PTCY of 50mg/kg with tacrolimus and post-engrafted low-dose anti-thymoglobulin (ATG) achieved low incidence of acute GVHD. More recently, it has been shown that reduced dose of PTCY of 40mg/kg is considered with similar efficacy as GVHD prophylaxis, In this study, a multi-center randomized comparison is planned to evaluate the clinical outcome of GVHD prophylaxis of PTCy 40 versus 50.

Post-transplantation cyclophosphamide (PTCY) is considered as major graft versus host disease (GVHD) prophylaxis. In our previous study, the investigators demonstrated that the standard dose PTCY of 50mg/kg with tacrolimus and post-engrafted low-dose anti-thymoglobulin (ATG) achieved low incidence of acute GVHD. In the clinical setting, reduced dose of PTCY (40mg/kg) was used for patients over 60 or with high HCT-CI and the overall incidence of acute GVHD was similar to PTCY 50mg/kg but chronic GVHD was slightly increased. To confirmed our observation, in this study, a prospective multiple-center randomized comparison is planned to evaluate the clinical outcomes of reduced dose of PTCY (40mg/kg) versus 50mg/kg as GVHD prophylaxis.

Inclusion Criteria:

• Patients with hematological malignancies
• Patients undergo allogeneic stem cell transplantation from haplo-identical donors
• Patents with informed consent provided

Exclusion Criteria:

• Patients with active infection ()bacteria, fungal or viral)
• Patients with liver, renal and cardiac dysfunction not suitable for undergoing allogeneic stem cell transplantation.