• All cur­rently enrolled patients with stable disease or better can con­tinue receiving selinexor
• Company has amended investigator’s brochure and informed consent documents as requested by FDA
• Company ex­pec­ts timelines for both ongoing and planned studies to remain ma­teri­ally unchanged

Newton, MA (Press Release) – Karyopharm Therapeutics Inc. (Nasdaq:KPTI), a clin­i­cal-stage pharma­ceu­ti­cal com­pany, today announced that it has received written notice from the U.S. Food and Drug Admin­istra­tion (FDA) that its clin­i­cal trials for selinexor (KPT-330) have been placed on partial clin­i­cal hold. While the partial clin­i­cal hold remains in effect, patients with stable disease or better may remain on selinexor ther­apy. No new patients may be enrolled until the partial clin­i­cal hold is lifted.

The FDA has indicated that the partial clin­i­cal hold is due to incomplete in­­for­ma­tion in the existing version of the investigator’s brochure (IB), in­­clud­ing an incomplete list of serious adverse events (SAEs) asso­ci­ated with selinexor. At the FDA’s request, Karyopharm has amended the IB and updated the informed consent documents accordingly and has submitted such documents to the FDA as requested. The partial clin­i­cal hold is not the result of any patient death or any new in­­for­ma­tion re­gard­ing the safety profile of selinexor. To date, more than 1,900 patients have been treated with selinexor in clin­i­cal trials across a variety of hema­to­logical and solid tumor malig­nan­cies.

As of Friday, March 10, 2017, Karyopharm had provided all requested ma­teri­als to the FDA believed to be required to lift the partial clin­i­cal hold. By reg­u­la­tion, the FDA has 30 days from receipt of Karyopharm’s sub­mission to notify the com­pany whether the partial clin­i­cal hold is lifted. Karyopharm is work­ing diligently with the FDA to seek the release of the partial clin­i­cal hold and resume enrollment in its selinexor clin­i­cal trials as expeditiously as possible. Karyopharm believes that its pre­vi­ously disclosed enrollment rates and timelines for its ongoing trials will remain ma­teri­ally unchanged.

About Selinexor

Selinexor (KPT-330) is a first-in-class, oral Selective Inhibitor of Nuclear Export / SINE™ com­­pound. Selinexor functions by binding with and inhibiting the nuclear export protein XPO1 (also called CRM1), leading to the accumulation of tumor sup­pressor proteins in the cell nucleus. This reinitiates and amplifies their tumor sup­pressor function and is believed to lead to the selective induction of apop­tosis in cancer cells, while largely sparing nor­mal cells. To date, over 1,900 patients have been treated with selinexor and it is cur­rently being eval­u­ated in several mid- and later-phase clin­i­cal trials across multiple cancer indi­ca­tions, in­­clud­ing in multiple myeloma in com­bi­na­tion with low-dose dexa­meth­a­sone (STORM) and back­bone ther­a­pies (STOMP), and in diffuse large B-cell lym­phoma (SADAL), and liposarcoma (SEAL), among others. Karyopharm plans to ini­ti­ate a pivotal ran­domized Phase 3 study of selinexor in com­bi­na­tion with bor­tez­o­mib (Velcade®) and low-dose dexa­meth­a­sone (BOSTON) in patients with multiple myeloma in early 2017. Additional Phase 1, Phase 2 and Phase 3 studies are ongoing or cur­rently planned, in­­clud­ing multiple studies in com­bi­na­tion with one or more approved ther­a­pies in a variety of tumor types to further inform the Company's clin­i­cal devel­op­ment priorities for selinexor. Additional clin­i­cal trial in­­for­ma­tion for selinexor is avail­able at www.clinicaltrials.gov.

About Karyopharm Therapeutics

Karyopharm Therapeutics Inc. (Nasdaq:KPTI) is a clin­i­cal-stage pharma­ceu­tical com­pany focused on the discovery and devel­op­ment of novel first-in-class drugs directed against nuclear transport and related targets for the treat­ment of cancer and other major diseases. Karyopharm's SINE™ com­­pounds function by binding with and inhibiting the nuclear export protein XPO1 (or CRM1). In addi­tion to single-agent and com­bi­na­tion activity against a variety of human cancers, SINE™ com­­pounds have also shown biological activity in models of neurodegeneration, inflammation, auto­immune disease, certain viruses and wound-healing. Karyopharm, which was founded by Dr. Sharon Shacham, cur­rently has several inves­ti­ga­tional pro­grams in clin­i­cal or pre­clin­i­cal devel­op­ment. For more in­­for­ma­tion, please visit www.karyopharm.com.

Forward-Looking Statements

This press release con­tains for­ward-looking state­ments within the meaning of The Private Se­cu­ri­ties Lit­i­ga­tion Reform Act of 1995. Such for­ward-looking state­ments in­clude those re­gard­ing the antic­i­pated impact of the partial clin­i­cal hold, timing of FDA review of Karyopharm’s response, Karyopharm’s plans for obtaining the release of the partial clin­i­cal hold, thera­peutic poten­tial of and poten­tial clin­i­cal devel­op­ment plans for Karyopharm's drug can­di­dates, in­­clud­ing the timing of initiation of and enrollment in certain trials. Such state­ments are subject to numerous im­por­tant factors, risks and un­cer­tain­ties that may cause actual events or results to differ ma­teri­ally from the Company's current ex­pec­ta­tions. For example, there can be no guar­an­tee that the FDA will release the partial clin­i­cal hold in a timely manner or at all, any of Karyopharm's SINE™ com­­pounds, in­­clud­ing selinexor (KPT-330), will suc­cess­fully com­plete nec­es­sary pre­clin­i­cal and clin­i­cal devel­op­ment phases or that devel­op­ment of any of Karyopharm's drug can­di­dates will con­tinue. Further, there can be no guar­an­tee that any pos­i­tive devel­op­ments in Karyopharm's drug can­di­date portfolio will result in stock price ap­pre­ci­a­tion. Management's ex­pec­ta­tions and, there­fore, any for­ward-looking state­ments in this press release could also be affected by risks and un­cer­tain­ties relating to a number of other factors, in­­clud­ing the fol­low­ing: Karyopharm's results of clin­i­cal trials and pre­clin­i­cal studies, in­­clud­ing sub­se­quent analysis of existing data and new data received from ongoing and future studies; the content and timing of de­ci­sions made by the FDA and other regu­la­tory author­i­ties, inves­ti­ga­tional review boards at clin­i­cal trial sites and publication review bodies, in­­clud­ing with respect to the need for addi­tional clin­i­cal studies; Karyopharm's ability to obtain and main­tain requisite regu­la­tory approvals and to enroll patients in its clin­i­cal trials; unplanned cash require­ments and ex­pen­di­tures; devel­op­ment of drug can­di­dates by Karyopharm's com­pet­i­tors for diseases in which Karyopharm is cur­rently devel­op­ing its drug can­di­dates; and Karyopharm's ability to obtain, main­tain and enforce patent and other intellectual property protection for any drug can­di­dates it is devel­op­ing. These and other risks are described under the caption "Risk Factors" in Karyopharm's Quarterly Report on Form 10-Q for the quarter ended September 30, 2016, which was filed with the Se­cu­ri­ties and Exchange Com­mis­sion (SEC) on November 7, 2016, and in other filings that Karyopharm may make with the SEC in the future. Any for­ward-looking state­ments con­tained in this press release speak only as of the date hereof, and Karyopharm expressly disclaims any obli­ga­tion to update any for­ward-looking state­ments, whether as a result of new in­­for­ma­tion, future events or other­wise.

Velcade® is a registered trademark of Takeda Pharma­ceu­tical Company Limited

Source: Karyopharm Therapeutics.