We randomly assigned patients with supratentorial glioblastoma to receive intravenous bevacizumab ( 10 mg per kilogram of body weight every 2 weeks ) or placebo , plus radiotherapy ( 2 Gy 5 days a week ; maximum , 60 Gy ) and oral temozolomide ( 75 mg per square meter of body-surface area per day ) for 6 weeks .