Given the possible synergism with irinotecan and bevacizumab for colorectal carcinomas, the combination has been studied in gliomas. In a study of 21 patients, the combination of irinotecan and bevacizumab produced a 43% response rate, with acceptable toxicity. The response rate is significantly higher than irinotecan alone and any other therapy for recurrent glioma. There were two serious adverse events, one intracranial hemorrhage and one bowel perforation. At the Duke Brain Tumor Center, the investigators have treated over 1000 glioblastoma patients with a bevacizumab-containing regimen, and there is marked clinical benefit and acceptable toxicity. Our initial study looking at the combination of bevacizumab and irinotecan for patients with recurrent glioblastoma published in 2007 found impressive response rates and survival and corroborated the earlier experience of Starks-Vance.~The investigators completed a study for newly diagnosed glioblastoma that utilized bevacizumab, radiation therapy and temozolomide followed by 6 months of bevacizumab, irinotecan and temozolomide. In addition, the group at University of California at Los Angeles published a study with bevacizumab, radiation therapy and temozolomide followed by 12 months of bevacizumab and temozolomide for newly diagnosed glioblastoma. These two phase II studies reported acceptable toxicity and a suggestion of improved survival compared to historical controls, and led to two large phase III randomized, placebo controlled studies of the addition of bevacizumab for newly diagnosed glioblastoma patients. The current proposal builds on the encouraging results of the addition of bevacizumab to the standard therapy for newly diagnosed glioblastoma patients. Two critical questions remain- the role of bevacizumab maintenance and bevacizumab at the time of progression in a patient previously treated with bevacizumab at the time of initial diagnosis. In addition, a retrospective analysis of data collected at our center from patients with recurrent disease suggests that continuation of bevacizumab at the time of progression may improve overall survival in comparison with cessation of bevacizumab.
Studies which have separately studied bevacizumab for recurrent gliomas and bevacizumab for newly-diagnosed glioma have shown good results and the regimens have been well-tolerated by patients. This study seeks to investigate the use of bevacizumab with the standard therapy (radiation therapy and temozolomide) in newly diagnosed patients, followed by bevacizumab and temozolomide with the continuation of bevacizumab following progression. Two critical questions remain- the role of bevacizumab maintenance and bevacizumab at the time of progression in a patient previously treated with bevacizumab at the time of initial diagnosis.