Age is a risk factor for graft-versus-host disease (GVHD) after human leukocyte antigen (HLA)-matched sibling allogeneic stem cell transplantation (allo-SCT). The incidence of acute GVHD is significantly higher in patients at 40 years of age or more than those at 18 to 39 years of age after allo-SCT. It was found that Anti-thymocyte globulins can be used for prophylaxis of both acute and chronic GVHD after allo-SCT.Prophylaxis of GVHD using ATG in patients at 40 years of age or more in matched sibling allo-SCT settings might significantly decrease the incidence of acute and chronic GVHD and the incidence of late effect after transplantation.

Prophylaxis for GVHD included CSA, MTX and MMF±ATG. In the trial group, CSA was started intravenously on day -1, at the dosage of 3 mg/kg, and switched to oral formulation as soon as the patient was able to take medication after engraftment. The dosage was adjusted to maintain a trough blood level of 200-300ng/ml. MMF was administered orally, 0.25g every 12 hours, from day -1 before transplantation to day 30 after transplantation. The dosage of MTX was 15 mg/m2, administered i.v. on day 1, and 10 mg/m2 on days 3, 6, and 11 after transplantation. ATG (Thymoglobulin 2.5mg/kg per day i.v.) on days -2 through -1. In the control group, CSA was started intravenously on day -1, at the dosage of 3 mg/kg, and switched to oral formulation as soon as the patient was able to take medication after engraftment. The dosage was adjusted to maintain a trough blood level of 200-300ng/ml. MMF was administered orally, 0.25g every 12 hours, from day -1 before transplantation to day 30 after transplantation. The dosage of MTX was 15 mg/m2, administered i.v. on day 1, and 10 mg/m2 on days 3, 6, and 11 after transplantation.

Inclusion Criteria:

• Standard-risk of recipients with hematological malignancies (including AML-CR1, ALL-CR1, CML-CP, MDS-RA, RARS,RCMD,RAEB-1); age from 40 to 60; having HLA-matched sibling donor; Eastern Cooperative Oncology Group (ECOG)≤1, ejection fraction (EF)≥50%; bilirubin≤35µmol/L; AST, and ALT lower than or equall to two-fold baseline;creatinie≤130µmol/L.

Exclusion Criteria:

• Active, uncontrolled infection; severe allergy to ATG, including shock or laryngeal edema; secondary stem cell transplant recipient; haplidentical recipients; matched unrelated donor recipients; non-myeloablative condioning regimen recipients; EF<50%; bilirubin>35µmol/L; AST, and ALT higher than two-fold baseline; creatinie>130µmol/L.