The value of measurable residual disease (MRD) in elderly patients with acute myeloid leukemia (AML) is inconsistent between those treated with intensive vs hypomethylating drugs, and unknown after semi-intensive therapy. We investigated the role of MRD in refining complete remission (CR) and treatment duration in the phase III PETHEMA-FLUGAZA clinical trial, that randomized 283 elderly AML patients to induction and consolidation with fludarabine plus cytarabine or induction and consolidation with 5-azacitidine. After consolidation, patients continued treatment if MRD≥0.01% or stopped if MRD<0.01%, assessed by multidimensional flow cytometry (MFC). On multivariate analysis including genetic risk and treatment arm, MRD status in patients achieving CR (N=72) was the only independent prognostic factor for cumulative-incidence of relapse (HR:2.95;P=.002) and relapse-free survival (HR:3.45;P=.002). A trend for longer overall survival was observed in patients with undetectable MRD (N=13/72). Although leukemic cells from most elderly AML patients display phenotypic aberrancies vs ... (Show More)

The value of measurable residual disease (MRD) in elderly patients with acute myeloid leukemia (AML) is inconsistent between those treated with intensive vs hypomethylating drugs, and unknown after semi-intensive therapy. We investigated the role of MRD in refining complete remission (CR) and treatment duration in the phase III PETHEMA-FLUGAZA clinical trial, that randomized 283 elderly AML patients to induction and consolidation with fludarabine plus cytarabine or induction and consolidation with 5-azacitidine. After consolidation, patients continued treatment if MRD≥0.01% or stopped if MRD<0.01%, assessed by multidimensional flow cytometry (MFC). On multivariate analysis including genetic risk and treatment arm, MRD status in patients achieving CR (N=72) was the only independent prognostic factor for cumulative-incidence of relapse (HR:2.95;P=.002) and relapse-free survival (HR:3.45;P=.002). A trend for longer overall survival was observed in patients with undetectable MRD (N=13/72). Although leukemic cells from most elderly AML patients display phenotypic aberrancies vs their normal counterpart (N=258/265), CD34 progenitors from cases with undetectable MRD by MFC displayed extensive genetic abnormalities identified by whole-exome sequencing. This study supports MRD assessment to refine CR after semi-intensive therapy or hypomethylating agents, but unveils that improved sensitivity is warranted to individualize treatment and prolong survival of elderly AML patients achieving undetectable MRD.

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