Stereotactic Radiosurgery With Nivolumab and Valproate in Patients With Recurrent Glioblastoma

Inclusion Criteria: * Confirmed malignant, recurrent glioblastoma or gliosarcoma * Subject must have adequate organ function * Subject must still be able to care for most of his or her personal needs Exclusion Criteria: * Subject is pregnant * Subject has extracranial metastatic or leptomeningeal disease * Subject has an additional malignancy that is progressing or requires active treatment, exceptions being basal cell and squamous cell carcinomas of the skin, indolent prostate cancer, chronic lymphocytic leukemia, or in situ cervical cancer * Subject has received chemotherapy, biological therapy, or had surgery 4 weeks prior to beginning the study * Subject has had radiation therapy within 10 weeks prior to entering beginning the study * Subject has had prior therapy with bevacizumab * Subject has had previous treatment with carmustine wafer except when administered as first-line treatment no less than six months prior to beginning the study * Subject requires escalating supraphysiologic doses of corticosteroids greater than 2 mg of dexamethasone or an equivalent * Active autoimmune disease requiring systemic treatment within the past 3 months or any syndrome that requires immunosuppressive agents * Interstitial lung disease or active, non-infectious pneumonitis * Evidence of greater than Grade 1 CNS hemorrhage or greater than Grade 3 venous thromboembolism * History of uncontrolled cardiac disease * Subject unable or unwilling to have a head contrast enhanced MRI