Prognostic impact of low allelic ratio FLT3-ITD and NPM1 mutation in acute myeloid leukemia

In the opinion of the European LeukemiaNet (ELN), nucleophosmin member 1 gene mutation ( NPM1 mut)–positive acute myeloid leukemia (AML) with an fms-like kinase 3-internal tandem duplication ( FLT3 -ITD) allele ratio (AR) FLT3 -ITD gene mutation–positive AML, dividing them into those with low AR and those with AR of ≥0.5 (high AR), and examined the prognostic impact according to allo-HSCT in CR1. Although FLT3 -ITD AR and NPM1 mut are used in the prognostic stratification, we found that NPM1 mut–positive AML with FLT3 -ITD low AR was not associated with favorable outcome (overall survival [OS], 41.3%). Moreover, patients in this group who underwent allo-HSCT in CR1 had a significantly more favorable outcome than those who did not (relapse-free survival [RFS] P = .013; OS P = .003). Multivariate analysis identified allo-HSCT in CR1 as the sole favorable prognostic factor (RFS P P NPM1 mut–positive AML with FLT3 -ITD low AR when allo-HSCT was not carried out in CR1.