• Age ≥18 years at the time of enrollment

• Diagnosed with 1 of the following diseases:

∙ Acute myeloid, or mixed phenotype leukemia in complete remission (CR) or CR with incomplete hematologic recovery (CRi), with or without the presence of known minimal residual disease.

‣ Myelodysplastic syndrome that is indicated for alloHCT per the 2017 International Expert Panel recommendations and/or therapy-related/secondary MDS as defined by the World Health Organization (WHO) classification of myeloid malignancies, with ≤10% blast burden in the bone marrow.

• Planned to undergo 1 of the following preparative regimens as per Investigator discretion:

∙ RIC cohort 1: Planned RIC-alloHCT including RIC regimen with TBI/thiotepa/fludarabine

‣ NMA cohort 2: Planned NMA-alloHCT including NMA regimen with fludarabine/cyclophosphamide/TBI

• Identified sibling or unrelated donor who is an 8/8 match for HLA-A, -B, -C, and -DRB1

• Estimated glomerular filtration rate ≥30 mL/minute

• Cardiac ejection fraction at rest ≥40% or shortening fraction of ≥22% by echocardiogram or radionuclide scan (MUGA)

• Diffusing capacity of the lung for carbon monoxide (adjusted for hemoglobin) ≥40%

• Negative serum or urine β-HCG test in women of childbearing potential

• Alanine transaminase (ALT)/aspartate transaminase (AST) \<5 times the upper limit of normal (ULN)

⁃ Total bilirubin \<3 × ULN

⁃ Deemed ineligible for a fully myeloablative alloHCT per assessment of the principal investigator