Phase 2 study of the Exportin 1 inhibitor selinexor in patients with recurrent gynecological malignancies

Background: Selinexor is an oral inhibitor of the nuclear export protein Exportin 1 (XPO1) with demonstrated antitumor activity in solid and hematological malignancies. We evaluated the efficacy and safety of selinexor in heavily pretreated, recurrent gynecological malignancies. Methods: In this phase 2 trial, patients received selinexor (35 or 50 mg/m2 twice-weekly [BIW] or 50 mg/m2 once-weekly [QW]) in 4-week cycles. Primary endpoint was disease control rate (DCR) including complete response (CR), partial response (PR) or stable disease (SD) ≥12 weeks. Secondary endpoints were progression-free survival (PFS), overall survival (OS) and safety. Results: 114 patients with ovarian (N = 66), endometrial (N = 23) or cervical (N = 25) cancer were enrolled. Median number of prior regimens for ovarian, endometrial and cervical cancer was 6 (1–11), 2 (1–5), and 3 (1–6) respectively. DCR was 30% (ovarian 30%; endometrial 35%; cervical 24%), which included confirmed PRs in 8%, 9%, and 4% of patients with ovarian, endometrial, and cervical cancer respectively. Median PFS and OS for patients with ovarian, endometrial and cervical cancer were 2.6, 2.8 and 1.4 months, and 7.3, 7.0, and 5.0 months, respectively. Common Grade 3/4 adverse events (AEs) were thrombocytopenia (17%), fatigue (14%), anemia (10%), nausea (9%) and hyponatremia (9%). Patients with ovarian cancer receiving 50 mg/m2 QW had fewer high-grade AEs with similar efficacy as BIW treatment. Conclusions: Selinexor demonstrated single-agent activity and disease control in patients with heavily pretreated ovarian and endometrial cancers. Side effects were a function of dose level and treatment frequency, similar to previous reports, reversible and mitigated with supportive care.