Allogeneic hematopoietic transplantation for acute and chronic myeloid leukemia: non-myeloablative preparative regimens and induction of the graft-versus-leukemia effect.

High-dose chemoradiotherapy with allogeneic blood or bone marrow transplantation is an effective and potentially curative treatment for advanced or high-risk hematologic malignancies, but it has been associated with significant morbidity and mortality resulting from toxicity of the preparative regimen, graft-versus-host disease, and the immunodeficient state that accompanies the procedure. Development of safer and less toxic treatment has been the subject of much research. This review summarizes the current understanding of the mechanisms by which allogeneic transplants cure leukemia and the rationale for non-myeloablative preparative regimens. Experience of the authors is related with 116 patients diagnosed with acute or chronic myeloid leukemia who underwent allogeneic hematopoetic transplantation with two non-ablative regimens that differed in intensity.