We assessed intratumoral penetration, safety, and efficacy of selinexor monotherapy for recurrent glioblastoma...single-agent selinexor induced responses and clinically relevant PFS6 with manageable side effects requiring dose reductions....The overall response rate (partial or complete) was 8.3% (n = 2; 95% CI, 1.0–27), 7.7% (n = 1; 95% CI, 0.2–36.0), and 10% (n = 3; 95% CI, 2.1–26.5), respectively (Table 2)....RNA-seq were performed on resected tumor specimens at the time of diagnostic surgery, before the recurrence, from 52 study patients from all arms with adequate selinexor exposure and evidence of either clinical benefit or resistance, as defined above. Among the identified recurrently mutated genes, patients whose tumors harbored mutations in pancreatic and duodenal homeobox 1 (PDX1, n = 5), E1A Binding Protein P400 (EP400, n = 13), or Dedicator of Cytokinesis 8 (DOCK8, n = 7) survived longer than patients with wild-type tumors (Supplementary Fig. S6).