Applying molecular measurable residual disease testing in acute myeloid leukaemia

Monitoring the KMT2A gene post-chemotherapy independently predicts the relapse and survival risk after allogeneic haematopoietic stem cell transplantation

This study evaluated the kinetics of KMT2A-r during chemotherapy and its impact on allogeneic haematopoietic stem cell transplantation (allo-HSCT) outcomes. KMT2A-r was assessed post-induction (MRD1), after the first (MRD2) and second (MRD3) consolidations and pre-transplant (MRD4) in 52 patients with acute myeloid leukaemia (AML). KMT2A-r significantly decreased from diagnosis to MRD2 (p < 0.001 for diagnosis vs. MRD1; p = 0.019 for MRD1 vs. MRD2). The incidence of KMT2A-r negativity (57.5%) peaked at MRD2. KMT2A-r status at each time point significantly affected post-transplant outcomes. Cluster analysis identified four KMT2A-r kinetic profiles: persistently negative (-/-), turned negative at transplant (+/-), turned positive at transplant (-/+) and persistently positive (+/+). The (-/-) group had the best outcomes, with a cumulative incidence of relapse (CIR) of 13.0%, overall survival (OS) of 82.0% and leukaemia-free survival (LFS) of 81.7%. The (+/+) group had the worst prognosis, with a CIR of 58.8%, OS of 29.4% and LFS of 23.5%. KMT2A dynamics were an independent risk factor for CIR (Hazard ratio [HR] = 11.070, 95%CI 2.395-51.165, p = 0.002), LFS (HR = 9.316, 95%CI 2.656-32.668, p < 0.001) and OS (HR = 7.172, 95%CI 1.999-25.730, p = 0.003). In conclusion, KMT2A-r status after chemotherapy and its kinetics are significant HSCT prognostic indicators.

Understanding differential technologies for detection of MRD and how to incorporate into clinical practice

Patient- and leukemia-specific factors assessed at diagnosis classify patients with acute myeloid leukemia (AML) in risk categories that are prognostic for outcome. The induction phase with intensive chemotherapy in fit patients aims to reach a complete remission (CR) of less than 5% blasts in bone marrow by morphology. To deepen and sustain the response, induction is followed by consolidation treatment. This postremission treatment of patients with AML is graduated in intensity based on this favorable, intermediate, or adverse risk group classification as defined in the European Leukemia Network (ELN) 2022 recommendations. The increment of evidence that measurable residual disease (MRD) after induction can be superimposed on risk group at diagnosis is instrumental in tailoring further treatment accordingly. Several techniques are applied to detect MRD such as multiparameter flow cytometry (MFC), quantitative (digital) polymerase chain reaction (PCR), and next-generation sequencing. The clinical implementation of MRD and the technique used differ among institutes, leading to the accumulation of a wide range of data, and therefore harmonization is warranted. Currently, evidence for MRD guidance is limited to the time point after induction using MFC or quantitative PCR for NPM1 and core binding factor abnormalities in intermediate-risk patients. The role of MRD in targeted or nonintensive therapies needs to be clarified, although some data show improved survival in patients achieving CR-MRD negativity. Potential application of MRD for selection of conditioning before stem cell transplantation, monitoring after consolidation, and use as an intermediate end point in clinical trials need further evaluation.