PB1764 THE ANALYSIS OF GENE MUTATIONS IN PATIENTS WITH ACUTE MYELOID LEUKAEMIA
Authors: Suvorov D. , Silin A. , Klimkovich N. , Martinkov V. , Kozich Z. , Shpudeyko V. 
Published: June 2019

Background:

Most AML patients present different cytogenetic and molecular defects associated with certain biologic and clinical features of the disease. Approximately 40–50 % of de novo AML patients demonstrate chromosomal aberrations. About half of the cases of AML are patients with normal karyotype from the subgroup with intermediate prognosis. However, phenotypically this group is heterogeneous and can be divided into prognostically different subgroups. Knowledge of genetic changes in AML patients allows to fully represent the development of the disease and assess the prognostic features of a particular variant of AML.

Aims:

To study the role of gene mutations in the diagnosis and prediction of AML.

Methods:

111 patients with AML (median age 53.2 years) were examined. DNA samples from blood and bone marrow were isolated by standard SDS‐method. Mutations FLT‐ITD and NPM1 were analyzed by PCR with specific primers. The FLT3 D835 mutation was analyzed using the RFLP‐PCR method with EcoRV restriction. CEBPA and p53 gene mutations were detected by SSCP‐TCR within the entire coding sequence of the gene.

Results:

In the study group, the mutation rate of FLT3‐ITD was 21.6 %, mutations of FLT3‐D835 ‐ 8%, mutations of NPM1 ‐ 21.6 %, mutations of CEBPA ‐ 11.3 %, mutations of p53 gene‐10.3 %. Statistically significantly more common mutations was evaluated in patients with a normal karyotype (p = 0.003) and in the group of intermediate prognosis (p = 0.001) compared with the group of AML with a poor karyotype. Depending on the AML variant, there were no differences in the mutation frequency of FLT3‐ITD (M0 11%, M1 17%, M2 24%, M3 32%, M4 17.6%). Mutations of FLT3 D835 were observed more often in M3 (16%) and M0 (11%) variants. Patients with M1 and M4 variants had no FLT3‐D835 mutation at all. NPM1 gene mutations were more common in M1 (28.6%) and M4 (24.5%) variants, in M2 and M3 17% and 16% respectively. Patients with M0 variant had no NPM1 gene mutation. When dividing patients with AML by age, there was no difference depending on the mutation status. Median age of patients with mutations in FLT3 gene was 50.6 (18…80) years, patients with NPM1 mutations – 55.9 (20…80) years. Patients with FLT3‐ITD and FLT3 ‐ D835 mutations had a higher number of leukocytes in the blood than in the group with NPM1 mutation (p = 0.022) and in the group without mutations (p = 0.003). Patients with FLT3‐ITD mutations had a higher content of blast cells in the bone marrow than patients without mutation (p = 0.038). The frequency of combined mutations in AML patients was 11.7%, of which FLT3‐ITD+NPM1‐8.1%, FLT3 D835+ NPM1 ‐ 0.9% and FLT3‐ITD + FLT3 D835 – 2.7%. Depending on the mutation status, the lowest overall survival was in patients with mutations FLT3‐ITD and FLT3‐ITD+FLT3‐D835. In the group of patients with a combination of mutation FLT3‐ITD+NPM1 overall survival did not differ from the group of patients without mutations (p = 0.112).

Summary/Conclusion:

The study of mutational status of genes FLT3 and NPM1 improves diagnosis of AML patients and allows to expand the group of prognostic markers. Flt3‐ITD mutation is associated with increased levels of leukocytes in peripheral blood and blasts in the bone marrow, as well as a negative impact on patient survival.