211At-BC8-B10 and Donor Stem Cell Transplant in Treating Relapsed or Refractory AML, ALL, or Myelodysplastic Syndrome

This phase I/II trial studies the side effects and best dose of astatine At 211 anti-CD45 monoclonal antibody BC8-B10 (211At-BC8-B10) followed by donor stem cell transplant in treating participants with acute myeloid leukemia, or acute lymphoblastic leukemia, or myelodysplastic syndrome that has come back or isn't responding to treatment. Monoclonal antibodies, such as 211At-BC8-B10, may interfere with the ability of cancer cells to grow and spread. Giving chemotherapy and total body irradiation before a stem cell transplant helps stop the growth of cells in the bone marrow, including normal blood-forming cells (stem cells) and cancer cells. When the healthy stem cells from a donor are infused into the participant, they may help the participant's bone marrow make stem cells, red blood cells, white blood cells, and platelets. Sometimes the transplanted cells from a donor can make an immune response against the body's normal cells, called graft versus host disease. Giving cyclophosphamide, tacrolimus, mycophenolate mofetil, and sirolimus after a transplant may stop this from happening.