Abstract B198: Selinexor (KPT-330), a novel Selective Inhibitor of Nuclear Export (SINE) shows marked NF-kB inhibition and significant anticancer activity against Non-Small Cell Lung Cancer (NSCLC).
Authors: Senapedis William , Crochiere Marsha , Rashal Tami , Kashyap Trinayan , Klebanov Boris , Saint-Martin Jean-Richard , Kalid Ori , Shechter Sharon , del Alamo Diego , Hamuza Mwanasha , Golan Gali , Shacham Eran , Tamir Sharon , McCauley Dilara , Baloglu Erkan , Kauffman Michael , Shacham Sharon , Landesman Yosef 
Published: August 2014

Selinexor (KPT-330) is a novel small molecule inhibitor of nuclear export through covalent binding to Exportin 1 (XPO1/CRM1) leading to forced nuclear retention of major tumor suppressor proteins (TSPs) such as p53, FOXO, pRB and IκB, resulting in selective death of cancer cells. Preclinical studies have shown that oral Selinexor is well tolerated, even with prolonged (4-8 month) administration. Human Phase 1 clinical studies with Selinexor in hematological and solid cancer patients are ongoing (Clinicaltrials.gov NCT01607892 and NCT01607905). In this study we evaluated the mechanisms involved in Selinexor-induced growth inhibition of NSCLC in vitro and in vivo.

Methods: A panel of NSCLC cells with various genetic backgrounds were treated with Selinexor and tested in proliferation (MTT), clonogenic survival, and flow cytometric assays. The cellular localization of TSPs were evaluated by immunofluorescence (IF). Western blotting was used to study levels of cell cycle regulating proteins and quantify markers of cell survival. Functional inhibition of NF-κB was measured using a transcription factor assay kit. A SCID mouse xenograft model of NSCLC, adenocarcinoma A549 (wt p53, NF-κB IC50 of 1.19 uM), was used to evaluate Selinexor effects in vivo and tumors were evaluated by histology and immunohistochemistry (IHC).

Results: Selinexor induced cell cycle arrest, inhibited tumor cell growth and clonogenic formation and induced apoptosis in lung cancer cell lines regardless of genetic background (IC50 25-700 nM). Treated normal human dermal fibroblasts entered into cell cycle arrest but resisted apoptosis induction (IC50 4.0 uM). IF of the TSPs p53, p21, IκB, E2F4, and survivin demonstrated strong nuclear localization after 4 to 24 hour treatment with Selinexor followed by apoptosis as determined by cleavage of PARP, caspases 3 and 8 by immunoblot analysis. Functional evaluation of NF-kB in A549 and H1299 revealed transcriptional repression with IC50 values similar to MTT assays. Finally, A549 xenografts treated with Selinexor (10 - 20 mg/kg QoDx3) showed marked tumor suppression when compared to vehicle and cisplatin-treated mice (growth inhibition was 78% at 20 mg/kg, p&lt;0.0001). Histological and IHC analysis of treated tumors indicated increased nuclear accumulation of p53, p21, FOXO1, survivin, NF-κB and IκB, reduced cell proliferation, and tumor cell death.

Conclusions: In NSCLC, Selinexor forces nuclear retention of TSPs, inhibits NF-κB transcriptional activity, inhibits tumor growth and induces cell death regardless of p53 status. Selinexor thus has therapeutic potential for the treatment of NSCLC.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B198.

Citation Format: William Senapedis, Marsha Crochiere, Tami Rashal, Trinayan Kashyap, Boris Klebanov, Jean-Richard Saint-Martin, Ori Kalid, Sharon Shechter, Diego del Alamo, Mwanasha Hamuza, Gali Golan, Eran Shacham, Sharon Tamir, Dilara McCauley, Erkan Baloglu, Michael Kauffman, Sharon Shacham, Yosef Landesman. Selinexor (KPT-330), a novel Selective Inhibitor of Nuclear Export (SINE) shows marked NF-kB inhibition and significant anticancer activity against Non-Small Cell Lung Cancer (NSCLC). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B198.