Wilms Tumor 1 Expression at Diagnosis Correlates With Genetic Abnormalities and Polymorphism But Is Not Independently Prognostic in Acute Myelogenous Leukemia : A Hokkaido Leukemia Net Study

The association between Wilms tumor 1 (WT1) expression, genetic abnormalities and homozygous single polymorphism (SNP) in WT1 gene was evaluated in 252 acute myelogenous leukemia (AML) patients. WT1 expression correlated with prognostic genetic abnormalities. Homozygous WT1 SNP rs16754 was associated with lower expression of WT1. WT1 expression had no prognostic impact in any cytogenetic group or SNP status. Background: The prognostic impact of WT1 expression at diagnosis of acute myelogenous leukemia (AML) has been controversial. The aim of this study was to determine the correlations of WT1 expression at diagnosis of AML with established prognostic alterations. Patients and Methods: We analyzed diagnostic bone marrow samples from 252 patients. WT1 expression, SNP in WT1 gene (rs16754), and Flt3-ITD mutation were analyzed for all patients. NPM1 mutation and CEBPA double mutation were analyzed for cytogenetically normal (CN)-AML. KIT mutation was analyzed for core-binding factor (CBF)-AML. Results: Within the cytogenetically favorable prognosis group, WT1 expression in AML with inv(16) or t(15;17) was significantly higher than that in AML with t(8;21). In cases with CN-AML, Flt3-ITD and NPM1 mutations were both correlated with higher expression of WT1, whereas CEBPA double mutation was related to lower WT1 expression. The existence of both Flt3- ITD and NPM1 mutations showed synergistically higher expression of WT1 in CN-AML. SNP in WT1 gene (rs16754) was significantly associated with lower expression of WT1. WT1 levels were not prognostic factors in the total cohort, in any cytogenetic group nor SNP status. Conclusion: Since WT1 expression correlated to known prognostic factors, the prognostic impact of WT1 levels might be misunderstood depending on the distribution of collaborative mutations in each cohort. We conclude that the prognostic significance of WT1 at diagnosis of AML is weak compared to other established prognostic factors