ARTICLE ABSTRACT
Purpose: We evaluated leukemia-associated immunophenotypes (LAIP) and their correlation with fms-like tyrosine kinase 3 (FLT3) and nucleophosmin (NPM1) gene mutational status in order to contribute a better identification of patients at highest risk of relapse in acute myeloid leukemia (AML).Experimental Design: Bone marrow samples from 132 patients with AML were analyzed by nine-color multiparametric flow cytometry. We confirmed the presence of the mutation in diagnostic samples and in sorted cells by conventional RT-PCR and by patient-specific RQ-PCR.Results: Within the CD34+ cell fraction, we identified a discrete population expressing high levels of the IL3 receptor α-chain (CD123) and MIC-2 (CD99) in combination with the IL2 receptor α-chain (CD25). The presence of this population positively correlated with the internal tandem duplications (ITD) mutation in the FLT3 gene (r = 0.71). Receiver operating characteristics showed that, within the CD34+ cell fraction a percentage of CD123/CD99/CD25+ cells ≥11.7% predicted FLT3–ITD mutations with a specificity and sensitivity of >90%. CD34/CD123/CD99/CD25+ clones were also detectable at presentation in 3 patients with FLT3 wild-type/NPM1+ AML who relapsed with FLT3-ITD/NPM1+ AML. Quantitative real-time PCR designed at relapse for each FLT3-ITD in these three cases confirmed the presence of low copy numbers of the mutation in diagnostic samples.Conclusions: Our results suggest that the CD34/CD25/CD123/CD99+ LAIP is strictly associated with FLT3-ITD–positive cells. Clin Cancer Res; 21(17); 3977–85. ©2015 AACR.
