Nilotinib and Imatinib Mesylate After Donor Stem Cell Transplant in Treating Patients With ALL or CML

PRIMARY OBJECTIVES: I. To determine the safety of the administration of nilotinib between Day 81 and Day 365 after hematopoietic cell transplantation (HCT) in patients with Philadelphia chromosome positive (Ph+) leukemia. SECONDARY OBJECTIVES: I. To quantify the breakpoint cluster region (BCR)/Abelson murine leukemia (ABL) transcript load after HCT during tyrosine kinase inhibitor therapy in patients with Ph+ leukemia treated sequentially with imatinib (imatinib mesylate) and nilotinib from the time of engraftment. II. To evaluate survival at 1 year in patients with Ph+ leukemia who received sequential imatinib and nilotinib from the time of engraftment. III. To determine if imatinib can be co-administered with nilotinib for patients with rising levels of BCR/ABL on 2 consecutive occasions after HCT. IV. To confirm that imatinib can be delivered at an average daily dose of 400 mg at least 85% of the time in the majority of adults during the first 80 days after HCT. V. To determine whether nilotinib can be administered safely at a daily dose of at least 300 mg (175 mg/m\^2 in children \< 17 years) at least 70% of the time to patients with imatinib resistant Ph+ leukemia during the first 80 days after HCT. VI. To determine treatment efficacy success at 1 year post-transplant as demonstrated by complete hematological remission, absence of Philadelphia chromosome, and not satisfying any of the criteria for treatment failure. OUTLINE: Beginning after engraftment and blood count recovery (21-28 days after allogeneic stem cell transplant), patients with imatinib-sensitive leukemia receive imatinib mesylate orally (PO) once daily (QD) until day 80 and then nilotinib PO twice daily (BID) on days 81-445. Patients with imatinib-resistant leukemia receive nilotinib PO BID beginning after engraftment and blood count recovery until day 445. Treatment continues in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically.