No abstract

Background. High-grade gliomas are characterized by a wide range of genetic abnormalities. The heterogeneous genomic landscape of pediatric high-grade gliomas allows identifying distinct subgroups of the disease in children and young adults. Most importantly, these subgroups differ by clinical course and prognosis, as well as treatment response to standard therapy.Objective: to assess the profile of molecular genetic markers of high-grade gliomas in children.Materials and methods. In the current study, we examine the frequency of H3F3A, Hist1H3B, BRAF, IDH1 / 2 mutations, the copy number alterations of CDKN2A / 2B genes and the expression of ETV6‑NTRK3 fusion gene in a cohort of 53 pediatric high-grade gliomas.Results. Driver mutations and CDKN2A / 2B deletions were observed in 24 (45 %) and 15 (28 %) of 53 tumors, respectively. Overall, the studied high-grade gliomas harbored 41 genetic aberrations including 24 (58.5 %) somatic missense mutations, 1 (2.4 %) genetic variant of unknown clinical significance, 1 (2.4 %) oncogenic fusion gene and 15 (36.6 %) deletions of the tumor suppressor genes.Conclusion. These findings point to the importance of molecular profiling of tumors for the optimal clinical care and development of new approaches to treatment aimed at molecular targets for personalized anticancer therapies.

п е р с п е к т и в н ы е и с с л е д о в а н и я

The main pathogenetic mechanism of the development of pediatric low grade gliomas (pLGGs) is genetic aberrations in BRAF gene. This study is supported by the Independent Ethics Committee and approved by the Academic Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology, and Immunology. We analyzed the clinical and molecular characteristics of 69 patients with LGGs. Molecular genetic testing for BRAF V600E mutation was performed by allele-specific real-time PCR and Sanger sequencing. BRAF V600E mutation was detected in 15 (21.7%) patients with LGG. The majority of BRAF-mutated cases of LGGs had the midline location: OPG – 7, subcortical ganglia – 1, brainstem – 2. The 2-year PFS was much worse in patients with BRAF V600E compared to patients without this mutation – 30% and 66.2%, respectively. The median time to progression for patients with BRAF V600E mutation was 9.5 months compared to 3.1 years for patients without indicated substitution. 5 patients with BRAF V600E-mutated LGGs who experienced progression after the conventional treatment, received targeted therapy (BRAF-inhibitor-3, BRAF + MEK inhibitors – 2) with good response (complete response – 2, partial response – 3). BRAF V600E mutation contributes to poor outcome in patients with LGGs Targeted therapy could be effective in this cohort of patients.