Real-world analysis of outcomes of patients receiving bevacizumab for recurrent glioblastoma in British Columbia.

Abstract

e14017 Background: Bevacizumab (Bev) has been publicly funded in British Columbia (BC) since 2011 for treatment of recurrent glioblastoma (rGBM). We performed a retrospective outcomes assessment of patients with rGBM treated with Bev to evaluate treatment practices and outcomes. Methods: Patients with rGBM treated at BC Cancer centers with Bev between January 2011 and December 2017 were reviewed. Patient demographics, tumor characteristics, treatment regimens, and dates of radiographic progression and death were collected. Kaplan-Meier method was used to assess survival, and comparisons were made using the log-rank test. Results: 182 patients were reviewed. There were 180 reported deaths with median PFS 3 months (CI95 = 2.5 - 3.5) and OS 7 months (CI95 = 6.2-7.8) from Bev initiation. Higher corticosteroid dose prior to Bev initiation was associated with worse OS on univariate and multivariate analysis ( p = 0.40 and 0.01, respectively). 67% of patients on corticosteroids reduced their dose shortly after Bev initiation. Most patients (68%) were treated with multiple lines of therapy prior to Bev, with a median time from chemoradiation to Bev initiation of 8 months (range 1-67). Patients started on Bev < 6 months from completion of chemoradiation (prior to adjuvant temozolomide completion) had improved PFS ( p = 0.02) and OS compared to those who started Bev later ( p = 0.05), but there was no association between extent of treatment prior to Bev and outcomes ( p = 0.09). Addition of chemotherapy to Bev did not improve survival over Bev monotherapy ( p = 0.10). Conclusions: Bev combinations with chemotherapy did not confer survival advantage over Bev monotherapy. Furthermore, our results show that patients receiving Bev before completion of adjuvant chemotherapy have better outcomes, suggesting pseudoprogression may have prompted the therapeutic switch. Despite limited benefits to overall survival, Bev is associated with reduction in corticosteroid use and likely improvement in quality of life. Therefore, further research is required to optimize patient selection for and administration of Bev. Additional analysis of rGBM patients prescribed Bev until 2020 in BC is currently underway.