Key Inclusion Criteria:

   - Patients designated to undergo allogeneic peripheral blood or bone marrow stem cell
   transplantation following the diagnosis of one of the primary diseases in early or
   intermediate disease status (i.e., acute myeloid leukemia, acute lymphoid leukemia,
   and myelodysplastic syndrome)

   - Patients with an unrelated HLA-A,-B, -C and -DRBI matched donor

   - Patients with a Karnofsky Performance Score ≥ 70%

Key Exclusion Criteria:

   - Clinically significant concomitant diseases (i.e., cardiac, pulmonary, renal and CNS)

   - Bacterial, viral, or fungal infections

   - Known positive for Hepatitis B surfaces antigen, or Hepatitis C antibody, or who have
   been tested positive for HIV

   - Patients with any concurrent malignancy. Cancer treated with curative intent < 5 years
   previously will not be allowed except for patients with resected basal cell carcinoma
   or treated cervical carcinoma in situ

   - Known contraindications to the administration of rabbit immunoglobulin antibodies

   - Hypersensitivity to methylprednisolone, tacrolimus, methotrexate or any excipients
   contains in these products