Abstract Details

Title Impact of EGFR Amplification in Newly Diagnosed Glioblastoma Treated with Adjuvant Temozolomide: Four-year experience of a single major tertiary care institution

Topic Neuro-oncology

Presentation(s) P2 - Poster Session 2 (5:30 PM-6:30 PM)

Poster/Presentation
Number 7-030

Objective The primary aim of this study was to determine whether epidermal growth factor receptor (EGFR) amplification status in newly diagnosed glioblastoma (GBM) patients who received at least six cycles of adjuvant temozolomide (TMZ) impacted progression free survival (PFS) and overall survival (OS).

Background Standard practice of post-surgical GBM treatment dictates six-weeks of TMZ chemoradiation followed by six cycles of adjuvant TMZ. Clinical practice often involves extending adjuvant TMZ beyond six cycles at the discretion of the clinician in the absence of tumoral progression. Previous investigations into EGFR amplification status as a prognostic factor in GBM have shown a possible correlation in a sub-set of patients who received TMZ chemoradiation followed by adjuvant TMZ, requiring further investigation.

Design/Methods

Data from 465 patients who underwent surgical intervention for GBM at a major tertiary care institution between July 2012 and September 2016 were analyzed. Only patients who underwent six-weeks of concurrent TMZ chemoradiation followed by at least six cycles (≥6) of adjuvant TMZ and were progression free 28-days after cycle-six were included. Patients with EGFR amplification versus non-amplification were compared using a multivariate proportional hazard Cox model analysis.

Results 167 newly diagnosed GBM patients who received both TMZ chemoradiation and adjuvant TMZ were included in final analysis. Of these, 60 patients received ≥6 cycles adjuvant TMZ and were progression free 28-days post cycle-six. Median OS was 23.11 months. Patients who were EGFR non-amplified had a PFS hazard ratio, HR=0.44, (confidence interval, CI=(0.21-0.91), p=0.026); and an OS HR=0.41, (CI=(0.18-094), p=0.036). MGMT methylation status was consistent with literature: MGMT unmethylated patients had a PFS HR=1.54, (CI (97.5%) = (0.75-3.15), p=0.24); and an OS HR=2.36, (CI (97.5%) = (1.08-5.17), p=0.032).

Conclusions Patients with newly diagnosed GBM who received TMZ chemoradiation followed by ≥6 cycles of adjuvant TMZ and were EGFR non-amplified had dramatically significant improvement in PFS and OS.

Authors/Disclosures
PRESENTER	No disclosure on file
	No disclosure on file
Anas Ahmed Moahmmed Saeed Bamashmos, MD (Cleveland Clinic Foundation)	No disclosure on file
	No disclosure on file
	No disclosure on file

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