Inclusion Criteria
• Age greater than 16
• Malignant hematologic disease (e.g., AML, ALL, MDS, lymphoma)
• Matched related or unrelated donor (≥7/8 HLA match at A, B, C, DRB1)
• Peripheral blood stem cell graft (HPC-Apheresis)
• Eligible for myeloablative or reduced-intensity conditioning
• Karnofsky performance status ≥60%
• Ability to consent and comply with follow-up
Exclusion Criteria
1. The participant is HIV antibody positive
2. The participant has a hypersensitivity to rabbit proteins or Thymoglobulin® pharmaceutical excipients, glycine or mannitol
3. The participant has active or chronic infection (i.e. infection requiring oral or IV therapy)
4. The participant (if female and of childbearing potential) is pregnant or breast-feeding at the time of enrollment
5. 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 transplant
6. 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 transplant2