MT2025-35 Allogeneic Hematopoietic Stem Cell Transplantation Using Reduced Intensity Conditioning Treosulfan and Fludarabine, With Post-Transplant Cytoxan (PTCy) for the Treatment of Hematological Diseases

Inclusion Criteria: * Patients 2-75 years of age * ≤7 5 years of age: Karnofsky score ≥ 70% (≥ 16 years) or Lansky play score ≥ 50 (\< 16 years) with appropriate organ criteria as below (in other inclusion criteria) * 5/6 or 6/6 related donor, OR a 5-8/8 HLA-A, B, C, DRB1 allele match unrelated donor, OR a haplotype (at least 5/10) related donor * adequate liver (no decompensated liver failure, Child Pugh A, AST/ALT \<5X ULN) and renal function (creatinine \<2.0) * absence of decompensated congestive heart failure, or uncontrolled arrhythmia and left ventricular ejection fraction ≥ 40% * DLCO FEV1, FVC ≥ 40% predicted, and absence of O2 requirement Exclusion Criteria: * Pregnant or breastfeeding * Evidence of untreated/uncontrolled HIV infection * Untreated active serious infection * Active CNS malignancy * CML in blast crisis not in a complete remission by abnormal blast count. * Less than 3 months since prior myeloablative transplant