This phase I/II trial studies the side effects and best dose of vorinostat when given together with temozolomide and radiation therapy and to see how well they work in treating patients with newly diagnosed glioblastoma multiforme. Vorinostat may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as temozolomide, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving vorinostat together with temozolomide and radiation therapy may kill more tumor cells.

PRIMARY OBJECTIVES: I. To determine the maximum tolerated dose (MTD) of vorinostat in patients with newly diagnosed glioblastoma multiforme (GBM) and gliosarcomas, who are also receiving concomitant radiation therapy (RT) and temozolomide (TMZ). (Phase I) II. To define the safety of vorinostat with RT and TMZ in this population. (Phase II) III. To determine the efficacy of vorinostat in combination with RT and TMZ followed by vorinostat in combination with TMZ in patients with newly-diagnosed GBM and gliosarcomas as measured by overall survival at 15 months (OS15). (Phase II) SECONDARY OBJECTIVES: I. To determine progression-free survival in newly diagnosed GBM and gliosarcoma patients treated with the study regimen. (Phase II) II. To further evaluate the safety profile of vorinostat in combination with RT and TMZ in this patient population. (Phase II) III. Determine the neurocognitive effects in patients treated on this protocol and correlate these results with outcome endpoints. (Phase II) TERTIARY OBJECTIVES: I. To explore the extent to which the tumor's molecular characteristics and expression profile correlate with outcome. II. Evaluate potential mechanisms of therapy resistance in tumor samples obtained at the time of tumor progression. OUTLINE: This is a phase I, dose-escalation study of vorinostat followed by a phase II study. Patients undergo radiotherapy and receive vorinostat orally (PO) once daily (QD) on days 1-5, 8-12, 15-19, 22-26, 29-33, and 36-40. Patients also receive temozolomide PO QD on days 1-42. Beginning 4-6 weeks later, patients receive vorinostat PO QD on days 1-7 and 15-21 and temozolomide PO QD on days 1-5. Treatment with vorinostat and temozolomide 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 every 2 months for 1 year, every 3 months for 1 year and then every 6 months for 3 years.