Post remission consolidation by autologous HCT for AML in CR1, negative implications for subsequent allogeneic HCT in CR2. A Study by the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

After autologous hematopoetic cell transplantation, (HCT in 1st complete remission (CR1), patients with acute myeloid leukemia (AML) may relapse and undergo allogeneic HCT in CR2. The aim of this study was to analyze outcome of allogeneic HCT performed in CR2 comparing patients with prior consolidation by autologous HCT vs. patients with chemotherapy consolidation. Included were 2619 adults, with allogeneic HCT in CR2, in 2000-2017 with (n=417) or without (n=2202) prior autologous HCT. Patient groups were not entirely comparable; patients with prior autologous HCT were younger, had less often a favorable cytogenetic profile, had more commonly donors other than matched siblings and more often received reduced intensity conditioning (RIC) conditioning. In multivariate analysis non relapse mortality (NRM) risks in patients with prior autologous HCT were 1.34 (1.07-1.67), p=0.01 after adjustment for age, cytogenetic risk, transplant year, donor, conditioning intensity, sex matching, interval diagnosis-relapse and relapse-allogeneic HCT as compared to chemotherapy consolidation. Similarly, risks of events in leukemia free survival and graft versus host disease, relapse free survival were higher with prior autologous HCT, 1.17 (1.01-1.35), p=0.03 and 1.18 (1.03-1.35) p= 0.02, respectively. Risk of death was also higher 1.13 (0.97-1.32) p=0.1 but this was not significant. Post remission consolidation with autologous HCT for AML in CR1 increases toxicity of subsequent allogeneic HCT in CR2.