Hematopoietic stem cell transplantation for chronic lymphocytic leukemia

Although hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many aggressive hematologic malignancies, the role of HSCT in chronic lymphocytic leukemia (CLL) has remained controversial. Now in the era of improved conventional treatment and better prognostication of long-term outcome, a review of autologous and allogeneic HSCT in CLL treatment is warranted.

Despite an improved disease-free survival in some patients, multiple, prospective, randomized autologous HSCT CLL trials fail to demonstrate an overall survival benefit as compared to conventional therapy. Allogeneic bone marrow transplantation, although limited by donor availability, can successfully eradicate CLL with adverse prognostic features. In the older CLL patients, nonmyeloablative allogeneic transplants are better tolerated than myeloablative transplants. Nonmyeloablative allogeneic transplants are less effective in heavily diseased burdened patients.

Outside of a clinical protocol, autologous HSCT for CLL cannot be justified. Nonmyeloablative allogeneic transplantation should be considered in high-risk populations early in the disease process, when disease burden is most easily controlled. Alternative donor selection using haploidentical donors and posttransplantation cyclophosphamide has the potential to vastly increase the availability of curative therapy in CLL while retaining a low treatment-related toxicity.