- Determine a minimal (short-duration) post-transplant immunosuppression regimen comprising cyclophosphamide and/or mycophenolate mofetil with or without tacrolimus that results in ≤ 20% incidence of grade II or higher acute graft-versus-host disease (GVHD) in patients with hematologic malignancies undergoing nonmyeloablative allogeneic bone marrow or peripheral blood stem cell transplantation from an HLA-identical related donor.