Eltanexor Effectively Reduces Viability of Glioblastoma and Glioblastoma Stem-Like Cells at Nano-Molar Concentrations and Sensitizes to Radiotherapy and Temozolomide

Current standard adjuvant therapy of glioblastoma multiforme (GBM) using temozolomide (TMZ) frequently fails due to therapy resistance. Thus, novel therapeutic approaches are highly demanded. We tested the therapeutic efficacy of the second-generation XPO1 inhibitor Eltanexor using assays for cell viability and apoptosis in GBM cell lines and GBM stem-like cells. For most GBM-derived cells, IC₅₀ concentrations for Eltanexor were below 100 nM. In correlation with reduced cell viability, apoptosis rates were significantly increased. GBM stem-like cells presented a combinatorial effect of Eltanexor with TMZ on cell viability. Furthermore, pretreatment of GBM cell lines with Eltanexor significantly enhanced radiosensitivity in vitro. To explore the mechanism of apoptosis induction by Eltanexor, TP53-dependent genes were analyzed at the mRNA and protein level. Eltanexor caused induction of TP53-related genes, TP53i3, PUMA, CDKN1A, and PML on both mRNA and protein level. Immunofluorescence of GBM cell lines treated with Eltanexor revealed a strong accumulation of CDKN1A, and, to a lesser extent, of p53 and Tp53i3 in cell nuclei as a plausible mechanism for Eltanexor-induced apoptosis. From these data, we conclude that monotherapy with Eltanexor effectively induces apoptosis in GBM cells and can be combined with current adjuvant therapies to provide a more effective therapy of GBM.

A phase I open-label study of selinexor with paclitaxel and carboplatin in patients with advanced ovarian or endometrial cancers

PURPOSE

Selinexor, a selective inhibitor of nuclear export, monotherapy causes nuclear accumulation of tumor-suppressor proteins and has anti-tumor activity in ovarian and endometrial cancers. The safety and tolerability of oral selinexor plus intravenous carboplatin and paclitaxel chemotherapy (selinexor + CP) was evaluated in this population.

PATIENTS AND METHODS

This phase I, 3 + 3 dose-escalation study assessed 4 selinexor + CP regimens. Patients in cohorts of 3, regardless of disease type, were administered 1 of 4 alternating regimens (selinexor at 30 mg/m2 or 60 mg plus CP at AUC 5 and 175 mg/m2 or 80 mg/m2, respectively) for 6-10 cycles (1 cycle = 21 days), followed by selinexor maintenance. Enrolled patients with ovarian cancer had received 1 prior platinum-based therapy. Patients with endometrial cancer were chemotherapy-naive or had received 1 prior platinum-based therapy. Response was evaluated every 9 weeks.

RESULTS

Twenty-three patients were treated (5 serous ovarian cancer; 18 endometrial cancer, including 6 carcinosarcomas). The most common treatment-related adverse events (TRAEs) were thrombocytopenia (100%), leukopenia (91%), and hyperglycemia (87%). The most common grade 3/4 TRAEs were leukopenia (70%), neutropenia (70%), lymphopenia (61%), anemia (57%), and alanine transaminase increase (43%). One treatment-related dose-limiting toxicity (grade 3 syncope) occurred. Twelve patients achieved a partial response and 1 achieved a complete response. Responses to all four regimens were observed in ovarian and endometrial cancers.

CONCLUSIONS

Combination selinexor + CP was safe and tolerated in advanced ovarian and endometrial cancers.