Conditioning intensity in middle-aged patients with AML in first CR: no advantage for myeloablative regimens irrespective of the risk group an observational analysis by the Acute Leukemia Working Party of the EBMT

In recipients of allogeneic hematopoietic stem cell transplantation with AML in CR1, reduced intensity (RIC) conditioning regimens are usually given to older patients and myeloablative regimens (MAC) to younger patients. We analyzed whether in middle-aged patients aged 40-60 years, MAC was superior to RIC in cytogenetically higher risk AML. Among 2 974 patients, 1638 had MAC and 1336 RIC transplants. Cytogenetics were high risk in 508, intermediate risk in 2297 and low risk in 169. Overall survival (OS) was higher in patients with RIC with low-risk cytogenetics but not in the intermediate- or poor-risk AML. Relapse incidence was lower with MAC in poor- and intermediate-risk AML. Nonrelapse mortality (NRM) was higher in MAC in all cytogenetic risk groups. Multivariate analysis confirmed a significant leukemia-free survival and OS advantage for RIC in low risk but no advantage of MAC in intermediate- and poor-risk leukemia. In patients aged 40-60 years, MAC has no advantage over RIC. We confirm lower relapse but higher NRM risks with MAC. MAC is not superior in patients with higher risk cytogenetics, but is inferior to RIC in the small cohort of AML patients with low-risk cytogenetics.