Selinexor (KPT-330) in Combination With Temozolomide and Radiation Therapy in Patients With Newly Diagnosed Glioblastoma

Selinexor will be administered orally at an initial dose of 80 mg. The first dose will be given on day 2 of radiation and will thereafter be administered weekly on the second day of weekly radiation on weeks 1, 2, 4, and 5. If this dose level is tolerated, the dose will be escalated to 60 mg twice a week (days 1 and 4) on weeks 1,2,4,5. The third and final dose level will also be 60mg administered twice weekly for 6 weeks starting on days 1 and 4 radiation.

Temozolomide will begin on the first day or evening prior of radiation and be administered orally daily at a dose of 75 mg/m\^2 during the radiation treatment. Temozolomide will continue until the completion of radiation and then will be stopped. Beginning 1-month post-radiation therapy (RT), the adjuvant temozolomide will be given per standard of care.

Radiation therapy (RT) will be administered daily (Monday to Friday)

Anti-emetic for breakthrough nausea.

2.5mg to 5mg once a day if weight loss is rapid.

To treat hyponatremia, add salt tablets to participants diet per institutional guidelines.

Treat diarrhea with an anti-diarrheal per institutional guidelines