P17.46.b Clinical Features and Molecular Profiling Using Next Generation Sequencing Among Glioma Patients: Retrospective Review From a Quaternary Brain Tumour Center in Canada

BACKGROUND Molecular characterization of tumours is an integral part of diagnosis, treatment decision-making, and prognostication among glioma patients. Next-generation sequencing (NGS) is increasingly being utilized to identify the molecular drivers of these tumours, potentially uncovering targetable alterations that ultimately guide therapy. This is the first study to describe the clinical features and NGS assay results among glioma patients in a brain tumour center in Canada. MATERIAL AND METHODS Consecutive adult glioma patients from 2022 to 2024 were identified. Demographic profile, clinical details, and tumour characteristics were collected through chart review. NGS testing was done using the Oncomine Comprehensive Assay v3. Molecular alterations were assigned based on the ESMO Scale for Clinical Actionability of molecular Targets (ESCAT). RESULTS A total of 187 patients (male 61%, female 39%) were reviewed with a mean age of 45 years at diagnosis. ECOG score was 1 for 114 (61%) patients. Seizure (43%) was the most common presenting symptom and the frontal lobe (43%) was the most common primary tumour location. Glioblastoma (42%) was the leading diagnosis, followed by astrocytoma (19%) and oligodendroglioma (17%). Majority of tumours had a WHO Grade of 4 (53%). MGMT promoter methylation was found in 68 (36%) of patients. Of the 187 patients, 158 (85%) had NGS testing completed. 150 of 158 patients had at least 1 alteration identified. Most common tier 1 alterations were mutations in TERT promoter (57, 36%), CDKN2A/B loss (32, 20%), and IDH1/2 (25, 16%). Most common tier 2 alterations were in TP53 (59, 37%), CDK4/6 amplification (21, 13%), and PIK3CA (18, 11%). Most common tier 3 alterations were in ATRX (9, 6%), MSH6 (7, 4%), and EGFR (6, 4%). Concurrent radiotherapy and temozolomide were given to 109 patients at diagnosis. Ten patients received targeted therapy (BRAF and MEK inhibitor=1, MEK inhibitor=4, FGFR inhibitor=1, IDH1/2 inhibitor=4). With a median follow-up of 22 months, disease progression was seen in 82 (44%) patients on follow-up. At the time of review, 116 (62%) patients were still alive. CONCLUSION We present real-world data on the clinical features and NGS assay results among glioma patients from Princess Margaret Cancer Centre. In the current era of precision oncology, NGS is integral in personalizing treatment approaches by identifying molecular targets to both proven therapies and novel agents under study. Significant associations between these molecular markers, the clinicodemographic features, and outcomes within our population will be presented.