Phase I/II Study to Evaluate the Safety and Clinical Efficacy of Atezolizumab (aPDL1) in Combination With Temozolomide and Radiation in Patients With Newly Diagnosed Glioblastoma (GBM)

PRIMARY OBJECTIVES: I. To evaluate the safety of atezolizumab in combination with radiation and temozolomide during the concurrent stage and in combination with temozolomide during the adjuvant stage. (Phase I) II. To evaluate the overall survival (OS) of atezolizumab in combination with radiation and temozolomide and in combination with temozolomide at onset of treatment. (Phase II) SECONDARY OBJECTIVES: I. To evaluate the overall response rate (ORR), duration of response, and progression free survival (PFS) of atezolizumab in combination with radiation and temozolomide during the treatment period. CORRELATIVE OBJECTIVES: I. Profiling tumor immune cell populations (example: immunohistochemistry \[IHC\] analyses of CD4, CD8, programmed death-1 \[PD-1\], programmed death-ligand 1 \[PD-L1\], and PD-L2). II. Profiling of tumor deoxyribonucleic acid (DNA), messenger ribonucleic acid (mRNA), microRNA and epigenetic profiling (DNA methylation) and evaluation of whole exome sequencing, RNA sequencing, microRNA sequencing and cell-free circulating tumor DNA (ctDNA). III. Peripheral blood collection for evaluation of circulating chemokines/cytokines. OUTLINE: This is a phase I study followed by a phase II study. PHASE I (CONCURRENT PHASE): Patients receive temozolomide orally (PO) daily on days 1-42 and atezolizumab intravenously (IV) over 30-60 minutes on day 1, 15, 29, and 42. Patients undergo radiation therapy (RT) 5 days per week (Monday-Friday) for 6 weeks in the absence of disease progression or unacceptable toxicity. PHASE II (ADJUVANT PHASE): Patients receive temozolomide PO on days 1-5 and atezolizumab IV over 30 minutes on days 1 and 15. Treatment repeats every 28 days for up to 12 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 30 days and then every 3 months.