Flow cytometric evidence of MRD (≥ 0.01% leukemic blasts for ALL or ≥ 0.5% leukemic blasts for AML detected in the bone marrow) OR Molecular/cytogenetic evidence of disease (FISH or PCR methodology) performed within 7 days And with the intent of going on to an allogeneic hematopoietic cell transplantation (HCT) independent of this study