ONC201 and Radiation Therapy Before Surgery for the Treatment of Recurrent Glioblastoma

Inclusion Criteria: * Participants must have histologically proven glioblastoma or gliosarcoma which is progressive or recurrent following radiation therapy +/- chemotherapy * Participants must have evaluable, supratentorial contrast-enhancing progressive or recurrent glioblastoma or gliosarcoma by magnetic resonance imaging (MRI) imaging within 14 days of study treatment initiation. Participants must be able to tolerate MRIs * Participants can have any number of prior relapses * Participants must have recovered from severe toxicity of prior therapy. The following intervals from previous treatments are required to be eligible: * 12 weeks from the completion of radiation * 6 weeks from a nitrosourea chemotherapy or mitomycin C * 23 days from temozolomide chemotherapy * 4-weeks from other cytotoxic therapy unless noted above * 4 weeks or 5-half-lives (whichever is shorter) from any other investigational (not Food and Drug Administration \[FDA\]-approved) agents (including vaccines) * Participants must be undergoing surgery that is clinically indicated as determined by their care providers. Patients must be eligible for surgical resection with the expectation that the surgeon is able to resect at least 300 mg of tumor with low risk of inducing neurological injury * Participants must be undergoing radiotherapy that is clinically indicated as determined by their care providers. The field of radiation must overlap the area of tumor planned for surgical resection. Partic…