Treosulfan, Fludarabine Phosphate, and Total-Body Irradiation Before Donor Stem Cell Transplant in Treating Patients With High-Risk Acute Myeloid Leukemia, Myelodysplastic Syndrome, Acute Lymphoblastic Leukemia

This phase II trial is studying how well giving treosulfan together with fludarabine phosphate and total-body irradiation followed by donor stem cell transplant works in treating patients with high-risk acute myeloid leukemia, myelodysplastic syndrome, acute lymphoblastic leukemia. Giving chemotherapy, such as treosulfan and fludarabine phosphate, and total-body irradiation before a donor bone marrow or peripheral blood stem cell transplant helps stop the growth of cancer cells. It may also stop the patient's immune system from rejecting the donor's stem cells. The donated stem cells may replace the patient's immune cells and help destroy any remaining cancer cells (graft-versus-tumor effect). Sometimes the transplanted cells from a donor can also make an immune response against the body's normal cells. Giving tacrolimus and methotrexate before and after transplant may stop this from happening