¹Hematology Branch, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda MD, USA

Correspondence: Dr AJ Barrett, Stem Cell Allogeneic Transplantation Section, Hematology Branch, NHLBI, NIH, Building 10, Hatfield CRC, Room 3-5330, 10 Center Drive MSC 1202, Bethesda, MD 20892-1202, USA. E-mail: barrettj@nhlbi.nih.gov

Received 22 March 2006; Revised 15 June 2006; Accepted 19 June 2006; Published online 27 July 2006.

Abstract

The realization in the 1990s that allogeneic stem cell transplants (SCT) have a potentially curative graft-versus-leukemia (GVL) effect in addition to the antileukemic action of myeloablative conditioning regimens was a major stimulus for the development of reduced-intensity conditioning (RIC) regimens, aimed primarily at securing engraftment to provide the GVL effect, while minimizing regimen-related toxicity. It is now over 10 years since RIC regimens were heralded as a new direction in the field of SCT. Over the last decade much has been learned about the ways in which the conditioning regimen can be tailored to provide adequate immunosuppression, and modulated to deliver a chosen degree of antimalignant treatment. The huge literature of clinical data with RIC transplantation now permits us to more clearly define the success and limitations of the approach. This review examines the origins of RIC SCT, explores the degree to which the initial expectations and purpose of the approach have been realized, and outlines some ways forward for the field.