[ FLT3 Gene Expression and Its Clinical Significance in Acute Myeloid Leukemia.]

OBJECTIVES: 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).

CONCLUSIONS: FLT3 gene has adverse impacts on complete remission of AML.High expression of FLT3 gene is associated with poor prognosis of patients with AML.