Bone marrow transplantation, or allogeneic hematopoietic stem cell transplant (HCT), is the only curative therapy for many patients with leukemia. Certain immune cells, called T cells, contained in the donor HCT graft can cause a "graft versus leukemia" (GVL) effect which eliminates leukemic cells. Unfortunately, there are also donor T cells in the HCT graft that can cause a condition called "graft versus host disease" (GVHD). GVHD is a life-threatening immune response that remains the major barrier to the success of transplantation. Dr. Bleakley [Richard Lumsden Foundation Investigator] is developing new approaches to separate the beneficial GVL effect from detrimental GVHD after bone marrow transplantation. She has identified specific subsets of immune cells that promote GVHD; these cells can then be eliminated to reduce the frequency or severity of GVHD, while at the same time maintaining and improving the GVL effect. The Continuation Grant will be used to move this study to the clinical trial phase.