NPM1-mutation-based measurable residual disease assessment after completion of two courses of post-remission therapy is a valuable clinical predictor of the prognosis of acute myeloid leukemia.

Recent studies have reported that measurable residual disease (MRD) analysis using NPM1 mutations helps determine whether allogeneic hematopoietic stem cell transplantation (allo-HSCT) is indicated in acute myeloid leukemia (AML) patients. However, the optimal timing and cutoff value for measuring MRD using genomic DNA remain undetermined. This study aimed to investigate the optimal timing and cutoff value to ascertain the value of NPM1 mutation in MRD assessment. NPM1-mutated MRD was quantified by real-time polymerase chain reaction of bone marrow samples from 56 patients with NPM1-positive AML who achieved hematological remission. The area under the receiver-operating characteristic curve was greatest when MRD was assessed after two courses of post-remission therapy with a cutoff value of 0.010% (specificity, 68.4%; sensitivity, 87.0%). Patients whose MRD was below the cutoff value throughout the course of treatment had significantly better overall survival and relapse-free survival rates. Of the 33 patients who did not undergo transplantation during the first remission, all of the 11 who were never MRD-negative at any point experienced a relapse. Evaluating MRD with a cutoff value of 0.010% after two courses of post-remission therapy helps predict prognosis and determine the indication for allo-HSCT.