A Phase II Study of Reduced-Intensity Allogeneic Stem Cell Transplant for High-Risk Chronic Lymphocytic Leukemia

The purpose of this study is to evaluate a treatment approach called reduced intensity allogeneic stem cell transplantation in patients with chronic lymphocytic leukemia (CLL) that is considered high-risk or has returned despite prior treatment.

Stem cells from a sibling or another compatible healthy person (donor) can be used as part of a useful therapy for CLL. Stem cells are cells that can grow into red blood cells, white blood cells, or platelets. After transplant, a donor’s stem cells may be able to recognize and kill the patient’s leukemia cells. This powerful reaction by the donor’s stem cells is known as the “graft-versus-leukemia” (GVL) effect.

In the past, patients needed high doses of chemotherapy and/or radiation before receiving a donor’s stem cells. It was thought that both high-dose therapy and the GVL effect were needed to control or destroy the cancer. However, these treatments could only be given to young patients or to patients without other significant medical problems, because of the serious side effects that those treatments can cause. Recently, using lower doses of chemotherapy without radiation has helped lower and/or eliminate some of the serious side effects. This approach is called a “reduced-intensity” transplant.

Patients in this study will receive chemotherapy, then stem cells from a donor, and then the drug rituximab after transplant to help destroy any remaining CLL cells. After the transplant, patients will also receive a drug to reduce the risk of graft-versus-host disease, a side effect of transplantation that can occur when the donor’s cells attack certain tissues in the body.