• Age 18.0 years or older at the time of enrollment.

• Participants undergoing allogeneic HCT for one of the following indications:

‣ Acute leukemia or chronic myelogenous leukemia with no circulating blasts and with less than 5% blasts in the bone marrow. Therapy related myeloid neoplasms are allowed.

⁃ Myelodysplasia/chronic myelomonocytic leukemia with no circulating blasts and with less than 10% blasts in the bone marrow (higher blast percentage allowed in MDS due to lack of differences in outcomes with \< 5% versus 5-10% blasts in this disease). Therapy related myeloid neoplasms are allowed.

⁃ Lymphoma \[follicular lymphoma, Hodgkin lymphoma, diffuse large B cell lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma, angioimmunoblastic T-cell lymphoma and anaplastic large cell lymphoma\].

• Planned NMA/reduced intensity conditioning regimen.

• Participants must have a related or unrelated PBSC donor as follows:

‣ Sibling donor must be a 6/6 match for HLA-A and -B at intermediate (or higher) resolution, and -DRB1 at high resolution using DNA-based typing and must be willing to donate peripheral blood stem cells and meet institutional criteria for donation. HLA-matched parents and children may be used as donors.

⁃ Unrelated donor must be a 7/8 or 8/8 match at HLA-A, -B, -C and -DRB1 at high resolution using DNA-based typing. Unrelated donor must be willing to donate peripheral blood stem cells and meet NMDP criteria for donation.

⁃ Donor selection must comply with 21 CFR 1271.

• Cardiac function: Left ventricular ejection fraction at least 45%.

• Estimated creatinine clearance greater than 60 ml/min using the 2021 CKD-EPI formula or 24-hour urine creatinine clearance.

• Pulmonary function: DLCO corrected for hemoglobin at least 40% and FEV1 predicted at least 50%.

• Liver function: AST/ALT \< 3x ULN; Total bilirubin \< 2 mg/dL excluding Gilbert's syndrome or hemolysis.

• Karnofsky Performance Score of at least 60%.

• Female participants (unless postmenopausal for at least one year before the screening visit, or surgically sterilized), agree to practice two effective methods of contraception at the same time, or agree to completely abstain from heterosexual intercourse, from the time of signing the informed consent through 15 months post-transplant. Fertility preservation methods will be left to institutional standards.

• Male participants (even if surgically sterilized), of partners of women of childbearing potential must agree to one of the following: practice effective barrier contraception or abstain from heterosexual intercourse from the time of signing the informed consent through 15 months post-transplant.

• Plans for the use of targeted small molecule inhibitor post-transplant maintenance therapy must be disclosed upon enrollment and must be used irrespective of the outcome of the randomization. Planned use of investigational maintenance agents is not permitted. Planned hypomethylating agents as maintenance therapy is not permitted.

• Voluntary written consent obtained prior to the performance of any study-related procedure that is not a part of standard medical care, with the understanding that consent may be withdrawn by the participant at any time without prejudice to future medical care.