Study of Low Intensity Conditioning and Immunotherapy for High-Risk Cancers of the Blood

This research project will focus on whether it is safe and effective to rely on donor cells to prevent relapse of leukemia, lymphoma, or other blood cancer after bone marrow stem cell transplant (SCT). For many patients with these conditions, a bone marrow transplant can be the only chance for cure. The standard type of bone marrow transplant involves giving very high-doses of chemotherapy and radiation to kill all the cancer cells followed by an infusion of bone marrow stem cells from a relative who is a bone marrow match. After the transplant the patient takes anti-rejection drugs for many months to prevent the donor's immune cells from causing a severe reaction called Graft-versus-Host Disease (GVHD), which can even be fatal. However, for some patients with certain types of high-risk cancer even this intense treatment is not effective and the cancer relapses. Is has been known for many years that some of the bone marrow cells from the donor can kill cancer cells. Recently, it has been discovered that sometimes patients who relapse after a bone marrow SCT can be cured by giving an infusion of donor white blood cells (called a donor leukocyte infusion or DLI). By giving a DLI BEFORE a relapse happens, hopefully relapse can be prevented. The high doses of chemotherapy and radiation therapy given prior to a standard bone marrow stem cell transplant can make a patient very sick and also increase the chance of getting severe GVHD. In this research study we are going to rely mainly on the donor cells to kill the cancer cells, and patients will receive dosages of chemotherapy that are lower than the usual dosages. It is thought that this low intensity conditioning will make the transplant safer without risking more relapses, however it is not know whether low intensity conditioning is safer than standard conditioning.