Immunosuppressive Preparation Followed by Blood Cell Transplant for the Treatment of Blood Cancers in Older Adults

Patients with adult leukemias, non-Hodgkin's lymphoma and multiple myeloma, can now be cured by allogeneic bone marrow transplantation (BMT). This curative effect has been ascribed to the use of high dose chemoradiotherapy and the antileukemia effect of the graft. The assumption that BMT relies on the myeloablative effect of high dose chemotherapy and total body irradiation (TBI), has largely restricted allogeneic bone marrow transplantation in adults to those under the age of 55 years. Toxicity related mortality increases progressively with age and although some transplant centers carry out BMT in patients up to the age of 60 years, it is generally accepted that treatment related mortality prohibits the use of allogeneic bone marrow transplantation in patients beyond the age of 55 years. Several in vitro studies have demonstrated the existence of donor-derived CD4 and CD8 positive lymphocytes with specific reactivity for the patients leukemia and a potent graft versus leukemia (GVL) effect. This GVL effect is best seen in patients with relapse CML after bone marrow transplantation where a single infusion of donor lymphocytes can induce complete remission. In this protocol, we treat older patients between the ages of 55 to 71 years with hematologic disorders with an allogeneic stem cell transplant from an HLA identical sibling, using intensive immunosuppressive regimen without myeloablation in attempts to decrease the transplant related toxicity while preserving the antileukemia effect of the graft. The low intensity nonmyeloablative conditioning regimen will provide adequate immunosuppression to allow stem cell and lymphocyte engraftment. T-cell replete, donor-derived, granulocyte colony stimulating factor (G-CSF) mobilized peripheral blood stem cells (PBSC) will be used to establish hematopoietic and lymphoid immune reconstitution. We will add back lymphocytes in patients with less than 75% donor marrow chimerism as an attempt to prevent graft rejection. The end points of this study are engraftment, degree of donor-host chimerism, incidence of acute and chronic GVHD, transplant related morbidity and mortality as well as survival.