Current status of reduced-intensity-conditioning allogeneic stem cell transplantation for acute myeloid leukemia

Allogeneic stem cell transplantation (allo-SCT) is the most efficient antileukemic treatment for acute myeloblastic leukemia (AML). However, elderly patients can rarely benefit from standard myeloablative allo-SCT because of an unacceptable rate of procedure-related toxicities. This point is critical when considering AML patients in first complete remission. The development of the so-called reduced-intensity conditioning (RIC) regimens appears to decrease allo-SCT-related toxicities, and has emerged as an attractive modality in AML patients not eligible for standard allo-SCT. Such RIC regimens aim primarily to provide the immune graft-versus-leukemia effect while causing little toxicity. Of note, treatment-related toxicity appears to be lower with RIC regimens as compared to standard myeloablative regimens. Nevertheless, toxicity might represent only one aspect of the problem, since AML encompasses a group of chemosensitive diseases, raising concerns that significant reduction of the intensity of the preparative regimen may have a negative impact on long-term leukemic control. Furthermore, no prospective studies have been reported thus far establishing RIC allo-SCT as the preferred option in AML. Investigators are currently faced with a dilemma on how to optimize the potential role of RIC allo-SCT in AML patients, while delivering minimal myeloablation and maximizing allogeneic immunotherapy. The aim of this review is to analyze the available research evidence in this field.