Hematopoietic Stem Cell Transplantation in the Treatment of Infant Leukemia

Inclusion Criteria: * Matched sibling donor (HLA 8/8), if available, or a unrelated partially HLA matched single unit based on the following priority: * 1st priority: 4/6 matched unit, cell dose \>5 x 10-7 nucleated cells/kg * 2nd priority: 5/6 matched unit, cell dose \> 4 x 10-7 nucleated cells/kg * 3rd priority: 6/6 matched unit, cell dose \> 3 x 10-7 nucleated cells/kg * Patients aged ≤ 3 years at diagnosis (not age of transplant) with hematological malignancy as detailed below: * Acute myeloid leukemia: high risk CR1 as evidenced by: * High risk cytogenetics t(4;11) or other MLL rearrangements; chromosome 5, 7, or 19 abnormalities; complex karyotype (\>5 distinct changes); ≥ 2 cycles to obtain complete response (CR); CR2 or higher; Preceding myelodysplastic syndrome (MDS); All patients must be in CR or early relapse (i.e., \<15% blasts in BM). * Acute lymphocytic leukemia: high risk CR1 as evidenced by: High-risk cytogenetic: t(4;11) or other MLL rearrangements; hypodiploid; t(9;22); \>1 cycle to obtain CR; CR2 or higher; All patients must be in CR as defined by hematological recovery, AND \<5% blasts by light microscopy within the bone marrow with a cellularity of ≥15%. * Myelodysplasia (MDS) IPSS Int-2 or High risk (i.e. RAEB, RAEBt) or refractory anemia with severe pancytopenia or high risk cytogenetics. Blasts must be \< 10% by a representative bone marrow aspirate morphology. * Persistent or rising minimal residual disease (MRD) after standard…