Nivolumab Plus Standard Dose Bevacizumab Versus Nivolumab Plus Low Dose Bevacizumab in GBM

Primary Endpoint(s) -To evaluate the efficacy of nivolumab when administered with standard and low bevacizumab dosing among recurrent glioblastoma patients as measured by the rate of overall survival at twelve months. Secondary Endpoint(s) * To evaluate the safety and tolerability of nivolumab in combination with bevacizumab administered according to standard and low dosage schedules for recurrent glioblastoma patients. * To compare progression free survival (PFS) at 6 months of nivolumab when administered with standard and low bevacizumab dosing for recurrent glioblastoma patients. * To compare the overall survival rate of nivolumab when administered with standard and low bevacizumab dosing for recurrent glioblastoma patients. * To compare progression free survival (PFS) of when administered with standard and low bevacizumab dosing for recurrent glioblastoma patients. * To compare the objective response rate (ORR) of nivolumab and bevacizumab administered according to standard and low dosage schedules for recurrent glioblastoma patients Study design and duration: This is a randomized, open-label, phase 2 safety study of nivolumab and bevacizumab administered according to standard and low dosage schedules in adult (≥ 18 years) participants with a first recurrence or second recurrence of glioblastoma (GBM). Participants must have received previous treatment with radiotherapy and one recurrence. The study will allow participants that require decadron up to 4mg/day to participate. Participants will undergo 1:1 randomization to receive treatment with either nivolumab (240 mg flat dosing IV every 2 weeks) and bevacizumab administered according to standard (10 mg/kg IV every 2 weeks; Arm A) and low (3 mg/kg IV every 2 weeks; Arm B) dosage schedules for recurrent glioblastoma participants. The study will allow participants that require decadron up to 4 mg/ day to participate in the study. Note - In view of the Covid 19 crisis, all in person visits can be substituted for virtual visit. All nursing toxicity checks can be performed over the phone rather than in person