[Clinical significance of MRD in AML]

Some studies have reported the clinical significance of minimal/measurable residual disease (MRD) in considering the prognostic stratification and therapeutic intervention after complete remission in acute myeloid leukemia (AML). In the clinical setting, multicolor flow cytometry (MFC), a quantitative PCR method targeting the expression of fusion genes generated by chromosomal translocation, such as PML-RARA, RUNX1-RUNXT1, and CBFB-MYH11, as well as WT1 mRNA, was used to detect MRD in AML. In recent years, quantitative PCR, next-generation sequence, and digital-droplet PCR methods targeting genetic alterations often detected in AML have been developed to assess its clinical significance. However, besides analysis methods, many common problems persist in MRD evaluation, such as sample collection points, type of samples, and threshold setting. Although several gene mutations involved in clonal hematopoiesis have been detected in CR patients, their presence did not correlate with the prognosis, and some leukemia-specific mutations did not always persist during the clonal evolution of AML. Therefore, it is essential to combine multiple methods, such as target gene mutation, quantitative PCR, and MFC to enhance the sensitivity of measurement. Furthermore, the establishment of novel treatment strategies incorporating MRD and molecular abnormalities is warranted for better clinical outcomes of AML.