Comparison of FLAMSA-based reduced intensity conditioning with treosulfan/fludarabine conditioning for patients with acute myeloid leukemia: an ALWP/EBMT analysis

FLAMSA followed by sequential reduced intensity conditioning and treosulfan/fludarabine are frequently used conditioning approaches used in centers of the European Society for Blood and Marrow Transplantation (EBMT) for older patients with acute myeloid leukemia (AML). It is currently unknown whether any of these regimens is superior to the others in terms of disease control and toxicity. Using the Acute Leukemia Working Party/EBMT multicenter registry we compared the outcomes of AML patients 45–65 of age transplanted between the years 2007 and 2016. A total of 629 patients were included in the analysis: 281 in the Treo/Flu group, 203 in the FLAMSA/TBI group, and 145 in the FLAMSA/Busulfan group. In multivariate analysis, FLAMSA/TBI conditioned patients had a decreased risk of relapse (hazard ratio (HR) = 0.43; 95% confidence interval (CI), 0.25–0.75; p= 0.002) and superior leukemia-free survival (HR = 0.67; 95% CI, 0.45–0.98; p= 0.042) compared to Treo/Flu conditioned patients. Rates of acute graft-versus-host disease (GVHD) were significantly higher in the FLAMSA/TBI group compared to the Treo/Flu group (HR = 2.004; 95% CI, 1.09–3.67; p= 0.024). Overall survival, non-relapse mortality, and chronic GVHD were not significantly impacted by the specific regimen used. The choice of either FLAMSA/TBI, FLAMSA/Bu, or Treo/Flu results in no major impact on survival of older AML patients.