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

Background: Glioblastoma is a type of brain cancer. Treatments include radiation, chemotherapy, and surgery. But survival rates are poor. Researchers think that the drug selinexor, when combined with chemotherapy and radiation, might help. Objective: To learn the highest dose of selinexor that people with brain cancer can tolerate when given with temozolomide and radiation therapy. Eligibility: People ages 18 and older with brain cancer that has not been treated with chemotherapy or radiation. Design: Participants will be screened under another protocol. Before participants start treatment, they will have tests: Neurological and physical evaluations Blood and urine tests Possible computed tomography (CT) scan or magnetic resonance imaging (MRI) of the brain if they have not had one in 3 weeks. Participants will lie in a machine that takes pictures of the body. They may have a dye injected into a vein. Surveys about their well-being Participants will have radiation to the brain for up to 6 weeks. This will usually be given once a day, Monday through Friday. Starting the second day of radiation, participants will take selinexor by mouth once a week. They will take it in weeks 1, 2, 4, and 5. The timing may be changed. Starting the first day of radiation, participants will take temozolomide by mouth once a day until they complete radiation. Participants will have blood tests once per week during treatment. Participants will have a follow-up visit 1 month after they complete treatment. Then they will have visits at least every 2 months for the first 2 years, then at least every 3 months for another year. Visits will include MRIs and blood tests.