Busulfan, Fludarabine Phosphate, and Anti-Thymocyte Globulin Followed By Donor Stem Cell Transplant and Azacitidine in Treating Patients With High-Risk Myelodysplastic Syndrome and Older Patients With Acute Myeloid Leukemia

This phase II clinical trial is studying how well giving busulfan, fludarabine phosphate, and anti-thymocyte globulin followed by donor stem cell transplant and azacitidine works in treating patients with high-risk myelodysplastic syndrome and older patients with acute myeloid leukemia. Giving low doses of chemotherapy, such as busulfan and fludarabine phosphate, before a donor stem cell transplant helps stop the growth of cancer cells. It also stops 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-vs-tumor effect). Sometimes the transplanted cells from a donor can also make an immune response against the body's normal cells. Giving anti-thymocyte globulin before transplant and giving azacitidine, tacrolimus, and methotrexate after the transplant may stop this from happening.