Nonmyeloablative Conditioning Regimen in Patients with High Risk Acute Myeloid Leukemia: Unrelated and Sibling Allogeneic Hematopoietic Stem Cell Transplantation

Abstract

It has been recently reported that it is possible to achieve fast engraftment with minimal transplant-related mortality and morbidity by using reduced-intensity preparative regimens based on fludarabine (Flu) combined with busulfan (Bu), antilymphocyte globulin (ATG), cyclophosphamide, melphalan or total body irradiation (TBI). We report our experience with HSCT using three different nonmyeloablative conditioning regimens in 27 high risk patients with acute myeloid leukemia (AML). Fourteen patients were male and 13 female. Twenty-four patients received unmanipulated peripheral blood stem cells (PBSC) from a sibling (n=8) or from a compatible unrelated donor (n=17), respectively. Two patients received bone marrow from HLA-mismatched related (n=l), HLA-compatible unrelated (n=l) donors. The reduced intensity preparative regimens were based on Bu/Flu, Bu/Flu/ATG and TBI/Flu in 10, 7 and 10 patients, respectively. Neutrophil engraftment was observed in 19 out of 21 evaluable patients. Six patients could not be evaluated for engraftment due to early death. Organ toxicity was minimal with mild mucositis and no major bleeding. Acute GvHD was recorded in 50% of the patients. Twelve patients achieved complete remission after transplantation. Complete chimerism was obtained in most patients with stable engraftment. Median follow-up was 7 months. In conclusion, this approach might be of benefit in a carefully selected patient population diagnosed with refractory AML.