CLAG-M or FLAG-Ida Chemotherapy and Reduced-Intensity Conditioning Donor Stem Cell Transplant for the Treatment of Relapsed or Refractory Acute Myeloid Leukemia, Myelodysplastic Syndrome, or Chronic Myelomonocytic Leukemia

OUTLINE: This a dose-escalation study of TBI. Patients are assigned to 1 of 2 arms. ARM I: Patients receive filgrastim (G-CSF) subcutaneously (SC) daily on days -9 to -4, cladribine intravenously (IV) over 2 hours daily on days -8 to -4, cytarabine IV over 2 hours daily on days -8 to -4, and mitoxantrone IV over 60 minutes daily on days -8 to -6. If white blood cell (WBC) \> 20,000/uL, filgrastim on days -9 and -8 may be omitted at physician discretion. Patients undergo TBI on either day -1 or 0 and HCT on day 0. GVHD PROPHYLAXIS: Patients receive cyclophosphamide IV over 1-2 hours daily on days 3-4, cyclosporine IV over 1-2 hours twice daily (BID) on days 5-60, and mycophenolate mofetil IV or orally (PO) BID on days 5-28 (transplant with related donors) or three times daily (TID) on days 5-35 (transplant with unrelated donors). After day 60, patients continue to receive cyclosporine tapered through day 180 at the discretion of the treating physician in the absence of GVHD. ARM II: Patients receive G-CSF SC daily on days -9 to -4, fludarabine IV over 30 minutes daily on days -8 to -4, cytarabine IV over 2 hours daily on days -8 to -4, and idarubicin IV over 60 minutes daily on days -8 to -6. If white blood cell (WBC) \> 20,000/uL, filgrastim on days -9 and -8 may be omitted at physician discretion. Patients undergo TBI on either day -1 or 0 and HCT on day 0. Patients receiving an unrelated cord blood (UCB) transplant also receive cyclophosphamide IV on day -2. GVHD PROPHYLAXIS: Patients who received peripheral blood stem cell transplant receive cyclophosphamide IV over 1-2 hours daily on days 3-4, cyclosporine IV over 1-2 hours BID on days 5-60, and mycophenolate mofetil IV or PO BID on days 5-28 (transplant with related donors) or TID on days 5-35 (transplant with unrelated donors). After day 60, patients continue to receive cyclosporine tapered through day 180 at the discretion of the treating physician in the absence of GVHD. Patients who received an UCB transplant receive cyclosporine IV, over 1 hour, every 8 hours (Q8H) from day -3 until day +100 and mycophenolate mofetil IV or PO TID on days 5-35. After day 100 patients continue to receive cyclosporine tapered up to at least 6 months post-transplant. Patients in both arms undergo multigated acquisition scan (MUGA) or echocardiography, and x-ray imaging during screening and as clinically indicated or per standard practice. Patients also undergo bone marrow biopsy and aspirate during screening, day 28, day 80 and at 1 year. Additionally, patients undergo blood sample collection throughout the study. After completion of study treatment, patients are followed up at 100 days, at 6, 12, and 24 months post-transplant.