History of consolidation is prognostic in acute myeloid leukemia patients undergoing allogeneic hematopoietic cell transplantation in minimal residual disease-negative first complete remission

Background: Prognostic factors among acute myeloid leukemia (AML) patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) in minimal residual disease (MRD)-negative first complete remission (CR1) are unknown. We retrospectively attempted to answer the following question: In AML patients undergoing allo-HCT in MRD-negative CR1, does a history of prior consolidation provide additional prognostic information?. Methods: The inclusion criteria were: (i) Age > 18 years, (ii) AML in CR1 after 1-2 cycles of intensive induction chemotherapy, with or without consolidation, (iii) Allo-HCT between 1/2003 and 4/2016 at our institution, (iv) Available standard-sensitivity 4-color flow cytometry results from a bone marrow aspiration at diagnosis and after completion of all previous chemotherapy within one month prior to HCT, (v) Flow cytometry-based MRD-negative status at the time of HCT. Results: A history of prior consolidation was associated with favorable overall survival (Hazard Ratio [95% Confidence Interval]: 0.59 [0.35-0.99], P =.046), relapse-free survival (0.60 [0.37-0.96], P =.036), and relapse (0.50 [0.27-0.92], P =.025). Analysis of potential sources of bias was unrevealing. Conclusions: In AML patients undergoing allo-HCT in MRD-negative CR1, a history of prior consolidation was associated with favorable outcomes. If the path to pre-HCT MRD negativity includes consolidation, it may identify patients with improved prognosis following HCT in MRD-negative state. These results warrant validation in larger cohorts.