[FLT3 gene overexpression and its clinical significance in acute myeloid leukemia with AML1/ETO fusion gene positive].

This study was aimed to investigate the expression levels of FLT3 gene in AML-M2 patients carrying AML1/ETO fusion gene, and analyze its relation with clinical and laboratorial features and prognosis. RQ-PCR method was used to detect the expression level of FLT3 in bone marrow of 21 AML-M2 patients with AML1/ETO(+). The correlation of the expression level of FLT3 with clinical features, other laboratorial examinations and disease prognosis were analyzed. The results showed that gene expression level of FLT3 (FLT3 gene/ reference gene) in patients at initial diagnosis were 1.65%-261.5%. The expression level of FLT3 over 35% was defined as high expression group (12 cases) , while the expression level below 35% was defined as low expression group (9 cases) . The proportion of patients with extramedullary infiltration in high expression group was higher than that in low expression group (25% vs 0%, P = 0.2286). The proportion of patients at initial diagnosis with white blood cell count > 10×10(9)/L in high expression group was higher than that in low expression group (66.67% vs 22.22%), but there was no statistical significance (P = 0.0805). No significant difference was observed at the age (P = 0.1369) and the rate of bone marrow blasts (P = 0.6923) between the above mentioned two groups. The differences in complete remission rate (66.67% vs 88.89%, P = 0.3383), the relapse rate (66.67% vs 22.22%,P = 0.0805) and the mortality rate (50% vs 22.22%, P = 0.3666) between the two group were not significant, but there was a clear trend that the low expression group has a higher CR rate and a lower relapse rate and mortality rate. It is concluded that FLT3 gene high expression in AML-M2 patients with AML1/ETO(+) have a higher rate of relapse and hence poor prognosis. Therefore, detection of FLT3 expression level in routine clinical practice is important for patient's risk stratification, prognostic evaluation and effective treatment selection.