Role for Reduced-Intensity Conditioning Regimen in AML After Allogeneic Transplantation

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Reduced-intensity conditioning and myeloablative-conditioning regimens following allogeneic hematopoietic cell transplantation in children with acute myeloid leukemia (AML) resulted in comparable survival, according to a study published in Blood. The study evaluated 181 patients, 39 treated with reduced-intensity conditioning and 141 treated with myeloablative-conditioning regimens.

“Results of univariate and multivariate analysis showed no significant differences in the rates of acute and chronic graft-vs-host disease, leukemia-free and overall survival between treatment groups,” reported ­Menachem Bitan, MD, PhD, of Tel Aviv Sourasky Medical Center, Israel, and colleagues.

“The 5-year probabilities of overall survival with [reduced-intensity conditioning] and [myeloablative-conditioning] regimens were 45% and 48%, respectively (P = .99). Moreover, relapse rates were not higher with [reduced-intensity conditioning] compared to [myeloablative-conditioning] regimens (39% vs 39%, P = .95), and recipients of [myeloablative-conditioning] regimens were not at higher risk for transplant-related mortality compared to recipients of [reduced-intensity conditioning] regimens (16% vs 16%, P = .73),” the investigators noted.

The study relied on data from the Center for International Blood and Marrow Transplant Research. Eligible patients were less than 18 years old (median age, 14), had received a first allogeneic transplant for AML between 2000 and 2009, and received reduced-intensity conditioning or myeloablative-conditioning conditioning regimens.

Regimens were considered to be of reduced intensity if busulfan was given at < 8 mg/kg orally or < 6.4 mg/kg intravenously, melphalan was given at < 150 mg/m2, and total-body irradiation was administered at 200 or 400 cGy as a single fraction or at 550 or 600 cGy in fractionated doses. Other regimens were defined as myeloablative, the authors explained.

About 50% of patients in the myeloablative-conditioning group received total-body irradiation, and the most frequently used non–total-body irradiation regimen was busulfan (Busulfex, Myleran) plus cyclophosphamide. About 20% of reduced-intensity conditioning regimens included low-dose total-body irradiation, and most of these regimens consisted of alkylating agents and fludarabine, the investigators noted.

“In this relatively modest study population and after carefully controlled analyses,” the authors concluded, “the data support a role for [reduced-intensity conditioning] regimens for acute myeloid leukemia in children undergoing allogeneic hematopoietic cell transplantation. The data also provide justification for a designing a carefully controlled randomized clinical trial that examines the efficacy of regimen intensity in this population.”

The authors pointed out that the results of observational trials comparing reduced-intensity conditioning and myeloablative-conditioning regimens in adults with AML and myelodysplastic syndrome have led to a national trial in the United States through the Blood and Marrow Transplant Clinical Trials Network.

Bitan M, et al: Blood. January 16, 2014 (early release online).