OS01.6 Glioblastoma in the era of bevacizumab: an epidemiological study in the Canton of Zurich, Switzerland

Background: The vascular endothelial growth factor antibody, bevacizumab (Avastin®), received approval for the treatment of recurrent glioblastoma in Switzerland in 2009. Here we explored the hypothesis that the approval of bevacizumab improved outcome in glioblastoma on a population level. Methods: The prognostic significance of epidemiological and clinical data, as well as molecular markers for glioblastoma patients diagnosed from 2010–2014 in the Canton of Zurich was analyzed using the log rank test and the Cox proportional hazards model. Data were compared to the years 2005–2009. Results: 310 glioblastoma patients were identified in the years 2010–2014. Median overall survival (OS) in this cohort was 13.1 months for all patients (independent of the isocitrate dehydrogenase (IDH) mutation status) and 13.5 months for patients with IDH wildtype (wt) tumors, compared with 11.3 months for all patients (p=0.554) and 11.3 months for IDH wt patients (p=0.675) before (2005–2009). In the present study, in the subgroup of IDH wt patients (n=247), 111 patients received bevacizumab at any time, half of them at time of first recurrence. Multivariate analysis demonstrated young age, high Karnofsky performance score, greater extent of resection, methylated O6-methylguanine DNA methyltransferase (MGMT) promoter, or first-line chemoradiotherapy, but not bevacizumab exposure, to be independently associated with survival. Conclusions: Despite a strong increase in bevacizumab use in the Canton of Zurich, Switzerland, on a population level, OS has moderately, but not significantly improved from 2005–2009 to 2010–2014. Our data do not support the notion that the minor increase in survival was directly linked to the availability of bevacizumab.