Cohort B: Glioblastoma up to and including third recurrence To qualify for Cohort B, patients must have previously been treated with involved-field radiation therapy with concurrent temozolomide chemotherapy, and pathology from the resection that qualifies the patient for the trial must be consistent with recurrent disease (ie, patients with predominantly pseudoprogression or radiation necrosis are not eligible). Patients who were initially diagnosed with low-grade glioma (ie, WHO grade 2 glioma) with subsequent progression to high-grade glioma are eligible for Cohort B provided they meet all other eligibility criteria. Patients with recurrent high-grade glioma are eligible up to and including third recurrence, and therefore are permitted to have been treated with up to three distinct chemotherapy regimens prior to trial enrollment. Prior and/or continued bevacizumab therapy is allowed.