Bevacizumab in Recurrent High-Grade Gliomas: A Canadian Retrospective Study

Background: Bevacizumab has been used in recurrent glioblastoma (rGBM) since 2010 in Canada. Given its cost, potential toxicities, and unclear efficacy, further studies are required to better define suitable candidates for therapy. Methods: A single-center retrospective review of patients started on bevacizumab for rGBM from 2012 to 2015 was performed. Patient demographics, tumor characteristics, treatment regimen, and dates of clinical progression and death were collected. Overall survival (OS) and progression-free survival (PFS) were used as clinical outcomes and estimates. Radiological response was assessed using modified Response Assessment in Neuro-Oncology criteria. Results: A total of 80 patients were included. There were 67 reported deaths, and the median OS was 9.2 months (95% confidence interval [CI95%]=7.0-10.1 months), with a 12-month OS of 31% (CI95%=21.9-43.5%). Some 79 patients were included for analysis of clinical progression, among whom 61 had documented clinical progression. The median clinical PFS was 4.6 months (CI95%=3.8-6.4 months), and the 6-month clinical PFS was 39% (CI95%=29.0-52.9%). Addition of chemotherapy did not improve clinical outcomes. A total of 68 patients were included for radiological progression analysis, with 58 radiological progressions. The median radiological PFS was 5.8 months (CI95%=4.2-6.7 months), and the 6-month radiological PFS was 46% (CI95%=35.6-60.0%). Conclusions: This is the first reported Canadian experience with bevacizumab for rGBM. Our clinical outcomes are consistent with published data from multicenter phase II and III trials on bevacizumab in rGBM. More research is required to determine which subtype(s) of patients with rGBM could benefit from bevacizumab upon recurrence.