Additional Study Information: The purpose of this research study is to see if Selinexor (KPT-330) has any effects against glioblastoma, a type of brain cancer. The study will be conducted at 3-5 sites in the United States and Europe and plan to enroll 30 patients with brain cancer. Patients will be screened prior to study participation. If their brain tumor is evaluated to require surgery they will be assigned to Group A, and they will receive 2 or 3 doses of the study drug Selinexor and then undergo surgery. After recovery from surgery patients will resume treatment with Selinexor. If patients do not require surgery they will be assigned to Group B. Patients will take Selinexor twice weekly on days 1 and 3 of each week (Monday and Wednesday or Tuesday and Thursday). One cycle is 28 days (4 weeks) and includes 8 doses of Selinexor. The term Cycle 1 is the first 4 weeks from the time patients take their first dose of Selinexor and Cycle 2 is the following 28 days or 4 weeks. The length of time that patients receive study treatment will depend on how well they tolerate the study drug and the effect it has on their brain cancer.