A Study of Selinexor in Combination With Standard of Care Therapy for Newly Diagnosed or Recurrent Glioblastoma

This is a Phase 1/2 study of selinexor in combination with standard of care (SoC) therapy for newly diagnosed glioblastoma (nGBM) or recurrent glioblastoma (rGBM). This study will be conducted in 2 phases: a Phase 1a dose finding study followed by Phase 1b (dose expansion) and a Phase 2 randomized efficacy exploration study and will independently evaluate 3 different combination regimens in 3 treatment arms in patients with nGBM (Arms A and B) or with rGBM (Arm C). * Arm A: evaluating the combination of selinexor with radiation therapy (S-RT) in nGBM participants with uMGMT * Arm B: evaluating the combination of selinexor with radiation therapy and temozolomide (TMZ) (S-TRT) in nGBM participants with methylated-O6-methylguanine-DNA-methyltransferase (mMGMT) * Arm C: evaluating the combination of selinexor with lomustine (or carmustine, if lomustine is not available) (S-L/C) in rGBM participants regardless of MGMT status * Arm D: evaluating the combination of selinexor with bevacizumab in rGBM participants regardless of MGMT status * Arm E: evaluating the combination of selinexor with tumor treating fields (TTField) in rGBM participants regardless of MGMT status