FLT3 Gene Expression and Its Clinical Significance in Acute Myeloid Leukemia

Objective To determine the correlation between fms-like tyrosine kinase 3 gene (FLT3) expression and FLT3-internal tandem duplication (ITD) mutations in acute myeloid leukemia patients, and the association between expression of FLT3 gene and clinical and laboratory features of patients. Methods The expression of FLT3 mRNA in bone marrow (BM) leukemic cells of 128 acute myeloid leukemia (AML) patients was measured by real-time PCR. The patients were divided into two groups using the 35% FLT3 expression as a cut-off point. The associations between the expression level of FLT3 and clinical and laboratory features of patients were analyzed. Results The patients had a FLT3 gene expression level of 0.01-180.68 （mean 14.65） at the initial diagnosis, with AML-M1 the most expressed and AML-M6 the least expressed, but without statistical significance. The patients with a high level of FLT3 gene expression had higher peripheral blood white blood cell count （WBC） （P<0.01） and were more likely to become anemic and febrile （P＜0.05）. WBC 〔regression coefficient （B）=1.508，odds ratio (OR)=4.518，95% confidence interval（CI）:1.465-13.390，P=0.009〕 and anemia （B=2.142，OR=8.513，95%CI:3.201-22.644，P＜0.001）were predictors of higher expression of FLT3. The patients with high levels of FLT3 gene expression had lower complete remission rate （32/83）, compared with those （36/44） with low levels of FLT3 gene expression （P<0.05）. The Cox regression analysis showed that the patients with higher levels of FLT3 gene expression had a higher risk of death （B=1.338，relative risk=3.810，95%CI:1.820-7.947，P<0.001）. The Kaplan-Meier analysis showed that the patients with higher levels of FLT3 gene expression had lower survival time (56.63%） than those with lower levels of FLT3 expression （70.45%, P＜0.05）. Conclusion FLT3 gene has adverse impacts on complete remission of AML. High expression of FLT3 gene is associated with poor prognosis of patients with AML.