Fludarabine Phosphate, Busulfan, and Anti-Thymocyte Globulin Followed By Donor Peripheral Blood Stem Cell Transplant, Tacrolimus, and Methotrexate in Treating Patients With Myeloid Malignancies

PRIMARY OBJECTIVE: I. Determine the incidence and severity of acute graft-versus-host disease (GvHD). SECONDARY OBJECTIVES: I. Determine the pharmacokinetics of intravenous (IV) busulfan including interdose variability and evaluation of a limited sampling strategy. II. Determine thymoglobulin (anti-thymocyte globulin) pharmacokinetics. III. Determine the incidence of donor engraftment. IV. Determine system toxicities \>= grade 3 per Common Terminology Criteria for Adverse Events (CTCAE) version (v.) 3. V. Determine the incidence and severity of chronic GvHD. VI. Determine the incidence of non-relapse mortality at day +100 and at 1 year (yr). VII. Determine the incidence of relapse. VIII. Determine relapse-free survival. IX. Determine the incidence of Epstein-Barr virus (EBV) activation. OUTLINE: Patients receive fludarabine phosphate intravenously (IV) over 30 minutes on days -9 to -6, busulfan IV over 3 hours on days -5 to -2, and anti-thymocyte globulin IV over 6 hours on days -3 and -2 and over 4 hours on day -1. Patients undergo allogeneic peripheral blood stem cell (PBSC) transplant on day 0. Patients then receive tacrolimus IV continuously or orally (PO) every 12 hours beginning on day -1 and taper to day 180 and methotrexate IV on days 1, 3, 6, and 11. After completion of study treatment, patients are followed at 1 year.