OBJECTIVETo investigate the clinical characteristics of acute myeloid leukemia(AML) patients with FLT3-ITD(Fms-like tyrosine kinase3, intenal tandem duplication) mutation and their response to treatment.

METHODSRetrospective analysis of 128 newly diagnosed AML (except type M3) patients was performed between January 2014 and July 2017. Patients were divided into FLT3-ITD mutated group and non-mutated group. Mutation detection was carried out by using polymerase chain reaction(PCR) and gene sequencing analysis. Standard 3 + 7 or CAG regimen were taken as the first induction chemotherapy, 4 cases received sorafenib, overall survival (OS) was calculated by Kaplan-Meier.

RESULTSNinety-seven patients can be evaluable for clinical data available; 4 patients were FLT3-TKD mutated, which accounted for 4.1%; 19 patients were FLT3-ITD mutated, which accounted for 19.59%(19/97). Median white blood cell count (WBC), percentage of peripheral blasts and LDH value were significantly higher in FLT3-ITD group than those in non-mutated group [64.65(1.07-587.92)×10/L vs 39.68 (0.45-203.81) ×10/L](P<0.01), [69.62(16-99)% vs 36.35(0-92) %](P<0.01 ) and [LDH 526(124-2 729)U/L vs 265(20-1977)U/L](P<0.05), respectively. The frequency of coexisting NPM1 mutation was higher in FLT3-ITD group than that in non-mutated group [36.8(7/19)% vs 6.8 (5/74) %](P<0.01). The CR+PR was lower in FLT3-ITD group than that in non-mutated group [31.6(6/19)% vs 64.9 (48/74)%](P<0.05). OS in FLT3-ITD group was significantly shorter than that in non-mutated group (5 vs 18 months)(P<0.05). There is no significant difference in OS between FLT3-ITD concomitant with and without NPM1 mutation groups(5 vs 5 months)(P>0.05). The median OS was 13 months for the FLT3-ITD patients taking sorafenib.

CONCLUSIONThe FLT3-ITD is a common mutation in AML, FLT3-ITD mutated AML is more likely concomitant with NPM1 mutation with higher number of WBC, percentage of peripheral blasts and LDH value, thus CR is low after the 1st treatment and survival is poor.