Similar overall survival with reduced vs. standard dose bevacizumab monotherapy in progressive glioblastoma

INTRODUCTION: Bevacizumab has demonstrated activity in glioblastoma (GBM), but the true benefits and optimal dose‐schedule are debated. A lower dose‐schedule than standard‐dose bevacizumab (10 mg/kg 2‐weekly) might offer similar benefits with lower costs. At our Institution, patients are randomly assigned at time of primary diagnosis to Neuro‐Oncologists, who have varying practices in terms of bevacizumab dose‐schedule upon progression. METHODS: In a retrospective analysis we examined overall survival (OS), measured from first administered bevacizumab dose until death, according to dose‐schedule. Patients with de novo WHO Grade IV GBM who received standard‐ or reduced‐dose (5 mg/kg 2‐weekly) bevacizumab were included. MGMT methylation status and time from diagnosis to bevacizumab start were examined as prognostic variables. Clinical benefit and a comparative cost analysis were assessed. RESULTS: In total, 1127 bevacizumab doses were administered to 118 patients [Median: 7, Range: 1‐44]. Median OS (mOS) was 5.8 months. 69 (59%) patients received standard‐dose bevacizumab (mOS: 5.97 months) and 49 patients received reduced‐dose (mOS: 5.7 months). No statistically significant difference in OS between dosing schedule was seen (HR: 1.11, P‐value: .584). Patients with MGMT methylated tumors (43%) had improved OS compared to those with unmethylated tumors; 7.03 vs 4.97 months (HR: 0.61, P‐value: .027). If all patients were treated with reduced‐dose bevacizumab, an estimated €2.4M cost reduction would be observed. CONCLUSIONS: In this retrospective study, reduced‐dose bevacizumab schedule resulted in similar OS to standard‐dose bevacizumab monotherapy with substantial cost savings. MGMT methylation appears to convey a survival benefit in the setting of bevacizumab treatment for progressive GBM.