Evaluation of the efficacy and tolerability of bevacizumab-based treatments in recurrent primary brain tumors: a multicenter real-world Turkish Oncology Group (TOG) study.

Background: Bevacizumab is widely used for recurrent high-grade glioma, but the real-world effectiveness of bevacizumab with or without irinotecan remains uncertain. We evaluated outcomes of bevacizumab-based regimens in a large multicenter Turkish cohort.

Methods: In this retrospective study from 30 centers, adults with recurrent glioblastoma or other primary brain tumors treated with a bevacizumab-containing regimen at first or second progression were included. Patients received bevacizumab monotherapy, bevacizumab plus low-dose weekly irinotecan, or bevacizumab plus standard-dose irinotecan every 14 days. Tumor response, progression-free survival (PFS), overall survival (OS), and toxicity were assessed. Prognostic factors were analyzed using Cox regression.

Results: A total of 437 patients were included; 78.0% had glioblastoma. Treatment consisted of bevacizumab monotherapy in 9.4%, bevacizumab plus weekly irinotecan in 8.5%, and bevacizumab plus irinotecan every 14 days in 82.2% of patients. The objective response rate was 41.6%, and the disease control rate was 80.1%. Median OS was 10.77, 7.37 and 9.77 months (log-rank p = 0.024), and median PFS was 5.77, 3.93 and 6.43 months (p = 0.005), respectively. On multivariable analysis, glioblastoma histology independently predicted shorter PFS and OS, whereas a higher number of treatment cycles and antiepileptic drug use were associated with longer PFS. For OS, the irinotecan-bevacizumab every-14-day regimen and a higher number of treatment cycles were associated with improved survival compared with bevacizumab monotherapy, while baseline corticosteroid use and discontinuation of bevacizumab-containing therapy were independent adverse prognostic factors.

Conclusions: In this large real-world cohort, bevacizumab-based therapy achieved meaningful disease control and survival in recurrent primary brain tumors. An irinotecan-bevacizumab regimen administered every 14 days was associated with superior OS at the expense of increased but manageable chemotherapy-related toxicity, supporting its use in appropriately selected patients.