Nonmyeloablative allogeneic stem cell transplantation for acute leukemia.

Allogeneic stem cell transplantation (ASCT) has traditionally included the administration of maximally tolerated doses of chemoradiotherapy, which have been associated with significant treatment-related toxicities. Thus, less intensive conditioning regimens have been explored as a safer alternative to conventional ASCT. Nonmyeloablative stem cell transplantation (NMSCT) has been one of the most promising recent developments in the treatment of hematologic malignancies, and early studies have yielded encouraging results with high engraftment rates and sustained remissions. This approach incorporates immunosuppressive doses of chemotherapy and radiotherapy to achieve a mixed donor-host hematopoietic chimeric state and allows the development of a donor immune-mediated graft-versus-leukemia effect as the primary means of disease eradication. This review discusses the background and rationale behind NMSCT and its impact on the treatment of patients with acute leukemia.