Post-bevacizumab Clinical Outcomes and the Impact of Early Discontinuation of Bevacizumab in Patients with Recurrent Malignant Glioma

PURPOSE: Bevacizumab±irinotecan is effective for treatment of recurrent malignant gliomas. However, the optimal duration of treatment has not been established. MATERIALS AND METHODS: Ninety-four consecutive patients with recurrent malignant glioma who were treated with bevacizumab at our institutions were identified. Patients who continued bevacizumab until tumor progression were enrolled in a late discontinuation (LD) group, while those who stopped bevacizumab before tumor progression were enrolled in an early discontinuation (ED) group. Landmark analyses were performed at weeks 9, 18, and 26 for comparison of patient survival between the two groups. RESULTS: Among 89 assessable patients, 62 (69.7%) and 27 (30.3%) patients were categorized as the LD and ED groups, respectively. According to landmark analysis, survival times from weeks 9, 18, and 26 were not significantly different between the two groups in the overall population. However, the LD group showed a trend toward increased survival compared to the ED group among responders. In the ED group, the median time from discontinuation to disease progression was 11.4 weeks, and none of the patients showed a definite rebound phenomenon. Similar median survival times after disease progression were observed between groups (14.4 weeks vs. 15.7 weeks, p=0.251). Of 83 patients, 38 (45.8%) received further therapy at progression, and those who received further therapy showed longer survival in both the LD and ED groups. CONCLUSION: In recurrent malignant glioma, duration of bevacizumab was not associated with survival time in the overall population. However, ED of bevacizumab in responding patients might be associated with decreased survival.