97P - Prospects of liquid biopsy in determining prognosis in children with HGG and DIPG

Background

The search for genetic markers of prognosis seems promising for individualization of treatment programs for patients with brain tumors. The aim of our study is to study the dynamics of the concentration of mutant DNA in the BRAF gene in peripheral blood plasma during and after radiation therapy and compare these data with the effect of treatment.

Methods

Digital droplet PCR (ddPCR) was used to determine the concentration of mutant tumor DNA in 209 blood plasma samples (groups included 57 patients with pons tumors and 29 patients with glioma of the other localization). The samples were obtained before the course of RT, during RT (5-8 fraction) and after RT (27-30 fraction). According to the results of radiation therapy, patients were divided into two groups: 1 – the onset of tumor recurrence less than 6 months after the end of the course of RT; 2 – stabilization of the process for 6 months or more after the end of the course of RT.

Results

A significant increase in the relative concentration of mutant (V600E) DNA of the BRAF gene in peripheral blood at the beginning of the RT course and its decrease by the end of the course in the relapse-free group was shown. No changes or an increase in BRAFV600E levels by the end of the RT course was typical for patients with relapse in the early stages.

Conclusions

Methods of liquid biopsy allow to estimate changes in the amount of mutant (tumor) DNA in peripheral blood plasma in children with brain glioma in RT. Increase in the level of mutant DNA correlates with a more stable effect of the treatment.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Federal State Budgetary Institution Russian Scientific Center of Roentgenoradiology (RSCRR) of the Ministry of Healthcare of the Russian Federation (Russian Scientific Center of Roentgenoradiology).

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.