Prognostic value of multicenter flow cytometry harmonized assessment of minimal residual disease in acute myeloblastic leukemia

Abstract

The assessment of minimal residual disease (MRD) in acute myeloblastic leukemia is of growing interest as a prognostic marker of patients' outcome. Multiparameter flow cytometry (MFC), tracking leukemia-associated immunophenotypic patterns, has been shown in several studies to be a useful tool to investigate MRD. Here, we report a multicenter prospective study which allowed to define a harmonized analysis strategy, as well as the efficacy of MFC MRD to predict outcome. This study included 276 patients, in 10 different MFC centers, of whom 268 had at least 1 MRD check point. The combination of a CD45, CD34, and CD33 backbone, with the addition of CD117, CD13, CD7, and CD15 in 2 five-color tubes allowed to define each patient's multiparameter immunophenotypic characteristics at diagnosis, according to a Boolean combination of gates. The same individual diagnosis gating strategy was then applied at each MRD time point for each patient. MRD levels were stratified according to log by log thresholds, from 5 × 10 (the classical morphological threshold to define remission) down to <5 × 10 . MRD was found to be constantly negative (<5 × 10 ) for 148 patients. Survival analyses significantly associated MRD negativity with a good prognosis and any positive value with poorer outcome. All P values were <0.0001 both for disease-free and overall survival at the earliest time point (post-induction, MRD1) as well as when considering all time points together. Finally, MRD levels were independent of cytogenetics and allowed in fact to further stratify all cytogenetics risk groups. In summary, this multicenter study demonstrates that a simple combination of immunophenotypic markers successfully allows for the detection of MRD in acute myeloblastic leukemia patients, with a strong correlation to outcome.

Clofarabine/busulfan-based reduced intensity conditioning regimens provides very good survivals in acute myeloid leukemia patients in complete remission at transplant: a retrospective study on behalf of the SFGM-TC

“…Other data suggested the same for MRD evaluation of WT1 expression before transplant [26]. In cases with no cytogenetic or molecular markers associated with the AML, MRD evaluated by flow cytometry can also be an effective tool to predict relapse risk after transplant [27, 28]. As suggested before, maybe it is time to move towards a MRD-based definition of CR [29], especially now that the establishment of a consensus on measurement and application of MRD in AML has been achieved [30].…”

An R‐Derived FlowSOM Process to Analyze Unsupervised Clustering of Normal and Malignant Human Bone Marrow Classical Flow Cytometry Data

“…The classical clustered blastic population appeared in fact to be composed of the superimposition of these subtly different subsets. The concepts of leukemia‐associated immunophenotypes or different from normal immunophenotypes found here a clear and immediately grasped definition. The importance of this degree of delineation for therapeutic or prognostic purposes is now being explored by our team within the European LeukemiaNet initiative .…”

How I investigate minimal residual disease in acute lymphoblastic leukemia

“…In some cases, a large sample volume must be concentrated, requiring the inclusion of and a pre‐lysing step, followed by a wash centrifugation and the staining procedure. However, a study has shown satisfactory results of the “lysis‐no‐wash” technique in the MRD assay 8 …”