ATG Plus PTCy vs ATG for CGVHD Prophylaxis

Patients with acute leukemia or myelodysplastic syndrome will be randomized to receive, or not receive, post transplant cyclophosphamide in addition to anti-thymocyte globulin.

Inclusion criteria

• The participant is aged ≥ 16 and deemed medically fit per investigator for protocol
• The participant has either acute myeloid leukemia in 1st or 2nd complete remission (CR), or has myelodysplastic syndrome
• The participant will receive a blood progenitor cell graft ("HPC, Apheresis")
• The participant has a related or unrelated donor, who is fully MHC matched with the recipient at HLA-A, B, C and DRB1.
• The participant meets the transplant centre's criteria for transplantation, using either myeloablative or reduced intensity conditioning.
• The participant has good performance status (Karnofsky ≥60%)
• The participant is able to understand and sign the informed consent form
• Ability and willingness to comply with study procedures and schedule, in the Investigator's opinion.
• The participant is receiving their first transplant

Exclusion criteria

• The participant is HIV antibody positive
• The participant has a hypersensitivity to rabbit proteins or Thymoglobulin® pharmaceutical excipients, glycine or mannitol.
• The participant has active or chronic infection (i.e. infection requiring oral or IV therapy)
• The participant (if female and of childbearing potential) is pregnant or breast-feeding at the time of enrollment
• The participant (if female and of childbearing potential) does not agree to use an adequate contraceptive method from the time of enrollment until a minimum of one year following transplant3
• The participant (if male and fertile) does not agree to use an adequate contraceptive method from the time of enrollment until a minimum of one year following transplant3
• The participant has urinary outflow obstruction
• The participant is in poor condition (determined per institutional guidelines)
• The participant has acute leukemia in relapse
• The participant has myelodysplastic syndrome with > 10% marrow blasts
• The participant is having their second transplant
• The participant is taking T-cell antibody prophylaxis (anti-CD52)
• The participant is receiving a cord blood graft or T-cell depleted grafts
• The participant has mixed phenotype acute leukemia
• The participant has prior malignancies, except resected nonmelanoma or treated cervical carcinoma in situ. Cancer treated with curative intent ≥ 5 years previously will be allowed. Cancer treated with curative intent < 5 years previously must be reviewed and approved by the sponsors.
• The participant is in complete remission with incomplete recovery (CRi)