Abstract General Information

Title

GENOMIC SEQUENCING IN GLIOMAS: CASE SERIES

Introduction, Objectives, Methods, Results, and Conclusion.

Introduction
Cancer understanding and treatment strategies have dramatically changed based on genomic tumor analysis. Primary brain tumors classification has been modified upon molecular basis. However, its treatment and prognosis has not yet found a turning point with immunotherapies or targeted therapies. Genomic sequencing might be a key tool to select better treatments.

Objectives
The objective of this work is to analyze the frequency and type of genomic alterations found in genomic sequencing of glial tumors.

Materials and methods
Retrospective review of clinical records from patients with histopathologic diagnosis of glial tumors was assessed at a tertiary neurological center in Buenos Aires, Argentina. Those with further analysis of whole genome next generation sequencing (NGS) were selected. Only patients over 16 years of age were included.

Results
Thirty-one patients were included, (20 men and 11 women) with a median age of 45 years (range 16-72). Histopathologic diagnosis was as follows; Glioblastoma n=18, Diffuse glial tumor n=9, Glioneural tumor n=3, Oligodendroglioma n=2.
Genomic sequencing was performed in 19 patients before oncologic treatment, and in 12 cases with tumor sample obtained after surgery at relapse.
Most frequent genomic alterations were; TERT 58% (18), CDKN2A/B 42% (13), TP53 54% (13), PTEN 35% (11), NF1 32% (10), MTAP 26% (8), IDH 23% (7). Other les frequent alterations were; ATRX (5), MTAP (5), PIK3 (5), EGFR (5), BRAF (5), RB1 (2), CDK4 (2), MDMD2 (2), FGFR3 (2), NOTCH1 (2), KEAP1 (2), among others. Microsatellite status was stable in all cases except one, and median tumor mutational burden was 3 (range 0-73). The only patient with microsatellite instability had a genetic diagnosis of Lynch Syndrome.

Conclusions
The most frequent genomic alteration in brain gliomas was found to be of the TERT gene. Microsatellite status is found to be stable in most brain primary tumors and tumoral mutational burden tends to be low with rare exceptions. Future analysis of large samples of brain tumor sequencing with NGS might clear up which are the most distinguishing features of genomic alterations in glial tumors.

Keywords (separated by comma on a single line)

Glioma, Genomic sequencing