Company to Host Conference Call to Discuss Second Quarter 2018 Financial Results and Recent Business Developments on Tuesday, August 7, 2018 at 8:30 a.m. ET

Newton, MA (Press Release) – Karyopharm Therapeutics Inc. (Nasdaq:KPTI), a clin­i­cal-stage pharma­ceu­tical com­pany, today announced the completion of the rolling sub­mission of a New Drug Application (NDA) to the U.S. Food and Drug Admin­istra­tion (FDA) seeking accelerated approval for selinexor, its novel, oral SINE com­­pound, as a new treat­ment for patients with penta-refractory multiple myeloma. Patients with penta-refractory myeloma have pre­vi­ously received the two pro­te­a­some inhibitors (PIs), Velcade® (bor­tez­o­mib) and Kyprolis® (car­filz­o­mib), the two immuno­modu­la­tory drugs (IMiDs), Revlimid® (lena­lido­mide) and Pomalyst® (poma­lido­mide), and the anti-CD38 mono­clonal anti­body Darzalex® (dara­tu­mu­mab) as well as alkylating agents, and their disease is refractory to at least one PI, at least one IMiD, Darzalex and their most recent ther­apy. Selinexor has received both Orphan Drug and Fast Track desig­na­tions from the FDA for this indi­ca­tion.

“There is a sub­stan­tial urgency for new ther­a­pies with novel mech­a­nisms for patients with highly resistant, penta-refractory myeloma,” said Sharon Shacham, PhD, MBA, Founder, Pres­i­dent and Chief Scientific Officer of Karyopharm. “The completion of our first NDA sub­mission marks a sig­nif­i­cant achieve­ment for Karyopharm and brings oral selinexor one step closer to these patients. We are sincerely grateful to the patients, care­givers and investigators that have con­trib­uted to the selinexor pro­gram to date, the Agency for work­ing with us with a sense of urgency and sup­port, and to the entire Karyopharm team for their inexhaustible professionalism and dedication to ad­vanc­ing this NDA.”

Pending mar­ket­ing approval by the FDA, Karyopharm plans to com­mer­cial­ize selinexor in the U.S. Should the appli­ca­tion be approved by the FDA, selinexor could be­come avail­able in the first half of 2019. The Company also plans to submit a Marketing Authorization Application to the European Medicines Agency in early 2019 with a request for con­di­tional approval.

Second Quarter 2018 Financial Results Conference Call Information

Karyopharm will report second quarter 2018 financial results on Tuesday, August 7, 2018. Karyopharm’s man­agement team will host a conference call at 8:30 a.m. ET on Tuesday, August 7, 2018, to discuss the second quarter 2018 financial results and recent business devel­op­ments. To access the conference call, please dial (855) 437-4406 (local) or (484) 756-4292 (international) at least 10 min­utes prior to the start time and refer to conference ID 3084449. A live audio webcast of the call will be avail­able under "Events & Presentations" in the Investor section of the Company's website, http://investors.karyopharm.com/events-presentations. An archived webcast will be avail­able on the Company's website approx­i­mately two hours after the event.

About Selinexor

Selinexor 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 2,600 patients have been treated with selinexor. In April 2018, Karyopharm reported pos­i­tive top-line data from the Phase 2b STORM study eval­u­ating selinexor in com­bi­na­tion with low-dose dexa­meth­a­sone in patients with penta-refractory multiple myeloma. For the STORM study’s pri­mary objective, oral selinexor achieved a 25.4% over­all response rate, which in­cluded two stringent com­plete responses, both of which were neg­a­tive for minimal residual disease, and 29 partial or very good partial responses. The median duration of response, a key sec­ond­ary objective, was 4.4 months, and patients with any response had a sig­nif­i­cantly prolonged over­all survival as com­pared with patients who did not respond. Selinexor has been granted Orphan Drug Desig­na­tion in multiple myeloma and Fast Track desig­na­tion for the patient pop­u­la­tion eval­u­ated in the STORM study. Karyopharm has submitted a New Drug Application (NDA) to the U.S. Food and Drug Admin­istra­tion (FDA), with a request for accelerated approval for oral selinexor as a new treat­ment for patients with penta-refractory multiple myeloma. The Company also plans to submit a Marketing Authorization Application (MAA) to the European Medicines Agency (EMA) in early 2019 with a request for con­di­tional approval. Selinexor is also being eval­u­ated in several other mid- and later-phase clin­i­cal trials across multiple cancer indi­ca­tions, in­­clud­ing in multiple myeloma in a pivotal, ran­domized Phase 3 study in com­bi­na­tion with Velcade® (bor­tez­o­mib) and low-dose dexa­meth­a­sone (BOSTON), as a poten­tial back­bone ther­apy in com­bi­na­tion with approved ther­a­pies (STOMP), in diffuse large B-cell lym­phoma (SADAL), liposarcoma (SEAL), and an investigator-sponsored study in endometrial cancer (SIENDO), among others. Additional Phase 1, Phase 2 and Phase 3 studies are ongoing or cur­rently planned, in­­clud­ing multiple studies in com­bi­na­tion with approved ther­a­pies in a variety of tumor types to further inform Karyopharm's clin­i­cal devel­op­ment priorities for selinexor. Additional clin­i­cal trial in­­for­ma­tion for selinexor is avail­able at www.clinicaltrials.gov.

Further Information About Potential Accelerated Approval for Selinexor in Multiple Myeloma

The FDA instituted its Accelerated Approval Program to allow for expedited approval of drugs that treat serious con­di­tions and that fill an unmet medical need based on a surrogate end­point or an intermediate clin­i­cal end­point thought to predict clin­i­cal benefit, like over­all response rate (ORR). Accelerated approval is avail­able only for drugs that provide a meaningful thera­peutic benefit over existing treat­ments at the time of con­sid­er­a­tion of the appli­ca­tion for accelerated approval, which the FDA has reiterated in its feedback to the Company. Particularly in disease areas with multiple avail­able and poten­tial new ther­a­pies, such as multiple myeloma, accelerated approval carries a high regu­la­tory threshold. Consistent with its general guidance, the FDA has noted to the Company its pref­er­ence for ran­domized studies geared to­ward full approval, which the Company has under­taken with the ongoing pivotal, Phase 3 BOSTON study, and has reminded the Company that accelerated approval requires patients to have exhausted all avail­able approved ther­a­pies. FDA’s Fast Track desig­na­tion is avail­able to thera­peutics treating an unmet medical need in a serious con­di­tion; the Company has received Fast Track desig­na­tion from the FDA specifically for the pop­u­la­tion treated in the STORM trial. In light of this recognition that the STORM patient pop­u­la­tion rep­re­sents an unmet medical need and the pos­i­tive top-line data reported in April 2018, the Company believes that the STORM study should sup­port its request to the FDA for accelerated approval.

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 sub­missions to regu­la­tory author­i­ties, in­­clud­ing the antic­i­pated timing of such sub­missions, and the poten­tial avail­a­bil­ity of accelerated approval path­ways, the thera­peutic poten­tial of and poten­tial clin­i­cal devel­op­ment plans for Karyopharm's drug can­di­dates, especially selinexor, and the plans for com­mer­cial­iza­tion. Such state­ments are subject to numerous im­por­tant factors, risks and un­cer­tain­ties that may cause actual events or results to differ ma­teri­ally from Karyopharm's current ex­pec­ta­tions. For example, there can be no guar­an­tee that any of Karyopharm's drug can­di­dates, in­­clud­ing selinexor, will suc­cess­fully com­plete nec­es­sary clin­i­cal devel­op­ment phases, that devel­op­ment of any of Karyopharm's drug can­di­dates will con­tinue or that any feedback from regu­la­tory author­i­ties will ultimately lead to the approval of selinexor or any of Karyopharm’s other drug can­di­dates. 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 U.S. Food and Drug Admin­istra­tion 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 March 31, 2018, which was filed with the Se­cu­ri­ties and Exchange Com­mis­sion (SEC) on May 10, 2018, 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, except as required by law, 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.
Revlimid® and Pomalyst® are registered trademarks of Celgene Corpo­ra­tion
Kyprolis® is a registered trademark of Onyx Pharma­ceu­ticals, Inc.
Darzalex® is a registered trademark of Janssen Biotech, Inc.

Source: Karyopharm Therapeutics Inc.