The randomization for this comparative trial will be stratified by conditioning regimen and, for those patients enrolled on MCC-14178, by busulfan AUC level.~All patients will receive daily doses of TAC beginning day -3 (day 0 being the day of hematopoietic stem cell transplant (HCT)) and will be given until day +60 when tapering will begin in the absence of GVHD. Provided no GVHD develops, TAC should be discontinued by day +180. Doses will be adjusted to maintain blood levels.~In addition to TAC, patients will be randomized to one of the following additional anti-GVHD medications: MTX or MMF beginning day 0 at least 2 hours after the end of the HCT. In the absence of GVHD a tapering schedule will begin on day +240 and be completed on day +360.~Study participants will be extensively monitored as inpatients and then weekly as outpatients. Some tests will be conducted at least twice weekly (blood tests, toxicity data, GVHD and physical exams) one-month post-transplant and during the tapering off periods for up to 2 years.
A comparative trial where all patients will receive daily doses of tacrolimus (TAC) until day +60 when tapering will begin, in the absence of graft-versus-host disease (GVHD), and discontinued by day +180. In addition patients will be randomized to methotrexate (MTX) or mycophenolate mofetil (MMF) and again, in the absence of GVHD, a tapering schedule will begin on day +240 and be completed on day +360. Doses will be adjusted to maintain blood levels.