Prognostic impact of low allelic ratio ITD and mutation in acute myeloid leukemia.

In the opinion of the European LeukemiaNet (ELN), nucleophosmin member 1 gene mutation ( mut)-positive acute myeloid leukemia (AML) with an fms-like kinase 3-internal tandem duplication (-ITD) allele ratio (AR) <0.5 (low AR) has a favorable prognosis, and allogeneic hematopoietic stem cell transplant (allo-HSCT) in the first complete remission (CR1) period is not actively recommended. We studied 147 patients with -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 -ITD AR and mut are used in the prognostic stratification, we found that mut-positive AML with -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] = .013; OS = .003). Multivariate analysis identified allo-HSCT in CR1 as the sole favorable prognostic factor (RFS < .001; OS < .001). The present study found that prognosis was unfavorable in mut-positive AML with -ITD low AR when allo-HSCT was not carried out in CR1.