Karyopharm Announces Presentations in Endometrial Cancer and Myelofibrosis at the 2024 American Society of Clinical Oncology Annual Meeting

Invited to Present Updated Endometrial Cancer Data During Special Session "ASCO Plenary Series: Rapid Abstract Updates"

NEWTON, Mass., April 24, 2024 /PRNewswire/ -- Karyopharm Therapeutics Inc. (Nasdaq: KPTI), a commercial-stage pharmaceutical company pioneering novel cancer therapies, today announced that several abstracts detailing new selinexor data have been selected for presentation at the 2024 American Society of Clinical Oncology Annual Meeting (2024 ASCO Annual Meeting) being held May 31 - June 4 in Chicago, IL. The Company is pleased to have received an invitation to present updated Endometrial Cancer data during a special session called "ASCO Plenary Series: Rapid Abstract Updates."

A highlight at the 2024 ASCO Annual Meeting includes a rapid oral abstract update of long-term follow-up of selinexor maintenance in patients with TP53wt advanced or recurrent endometrial cancer - a pre-specified subgroup analysis from the Phase 3 ENGOT-EN5/GOG-3055/SIENDO Study.

"As we follow the endometrial cancer patients whose tumors are TP53wt and evaluate the long-term benefit, our confidence for selinexor to provide meaningful benefit for patients continues to grow," said Reshma Rangwala, MD, PhD, Chief Medical Officer of Karyopharm. "We are excited about the advancement of our three, phase three programs in areas of high unmet need in endometrial cancer, myelofibrosis, and multiple myeloma."

Details for the 2024 ASCO Annual Meeting abstracts are as follows:


                                     
            
          Abstract Title              Presentation
                                                                                      Type            Abstract #              Session Date/Time



            
              Endometrial Cancer



            Updates on Abstract 427956: Long-Term                    Rapid Oral                          427956    June 1, 2024
    Follow up of Selinexor Maintenance in
    Patients with TP53wt Advanced or
    Recurrent Endometrial Cancer-A Pre-
    Specified Subgroup Analysis from the                                                                         12:30pm-1:30pm CDT
    Phase 3 ENGOT-EN5/GOG-3055/SIENDO Study

            (Rapid abstract update presentation
    following July 25, 2023 Plenary Series)



            Phase 3 Dose Selection for Selinexor in                
     Poster                                5594    June 3, 2024
    TP53wt Endometrial Cancer Based on
    Exposure-Response Analysis

                                                                                                                 9:00am - 12:00pm CDT



            
              Myelofibrosis



            Phase 3 Trial Design: Randomized                       
     Poster                  TPS6594              June 3, 2024
    Double-Blind Study Evaluating Selinexor,
    an XPO1 inhibitor, Plus Ruxolitinib in Jaki-
    Naïve Myelofibrosis
                                                                                                                 9:00am - 12:00pm CDT



            Phase 2 Study Trial Design: Evaluating                 
     Poster                  TPS6593              June 3, 2024
    Selinexor Monotherapy in Patients with
    Jaki-Naïve Myelofibrosis and Moderate
    Thrombocytopenia
                                                                                                                 9:00am - 12:00pm CDT

About XPOVIO® (selinexor)
XPOVIO is a first-in-class, oral exportin 1 (XPO1) inhibitor and the first of Karyopharm's Selective Inhibitor of Nuclear Export (SINE) compounds to be approved for the treatment of cancer. XPOVIO functions by selectively binding to and inhibiting the nuclear export protein XPO1. XPOVIO is approved in the U.S. and marketed by Karyopharm in multiple oncology indications, including: (i) in combination with Velcade® (bortezomib) and dexamethasone (XVd) in patients with multiple myeloma after at least one prior therapy; (ii) in combination with dexamethasone in patients with heavily pre-treated multiple myeloma; and (iii) in patients with diffuse large B-cell lymphoma (DLBCL), including DLBCL arising from follicular lymphoma, after at least two lines of systemic therapy. XPOVIO (also known as NEXPOVIO® in certain countries) has received regulatory approvals in a growing number of ex-U.S. territories and countries, including Europe, the United Kingdom, South Korea, Israel, Singapore, Hong Kong, Mainland China, Australia, Canada, Taiwan and Macau and is marketed in those areas by Karyopharm's global partners. Selinexor is also being investigated in several other mid- and late-stage clinical trials across multiple high unmet need cancer indications, including in endometrial cancer and myelofibrosis.

For more information about Karyopharm's products or clinical trials, please contact the Medical Information department at:
Tel: +1 (888) 209-9326,
Email: medicalinformation@karyopharm.com

XPOVIO(®) (selinexor) is a prescription medicine approved:

    --  In combination with bortezomib and dexamethasone for the treatment of
        adult patients with multiple myeloma who have received at least one
        prior therapy (XVd).


    --  In combination with dexamethasone for the treatment of adult patients
        with relapsed or refractory multiple myeloma who have received at least
        four prior therapies and whose disease is refractory to at least two
        proteasome inhibitors, at least two immunomodulatory agents, and an
        anti?CD38 monoclonal antibody (Xd).
    --  For the treatment of adult patients with relapsed or refractory diffuse
        large B?cell lymphoma (DLBCL), not otherwise specified, including DLBCL
        arising from follicular lymphoma, after at least two lines of systemic
        therapy. This indication is approved under accelerated approval based on
        response rate. Continued approval for this indication may be contingent
        upon verification and description of clinical benefit in confirmatory
        trial(s).

SELECT IMPORTANT SAFETY INFORMATION

Warnings and Precautions

    --  Thrombocytopenia: Monitor platelet counts throughout treatment. Manage
        with dose interruption and/or reduction and supportive care.


    --  Neutropenia: Monitor neutrophil counts throughout treatment. Manage with
        dose interruption and/or reduction and granulocyte colony?stimulating
        factors.


    --  Gastrointestinal Toxicity: Nausea, vomiting, diarrhea, anorexia, and
        weight loss may occur. Provide antiemetic prophylaxis. Manage with dose
        interruption and/or reduction, antiemetics, and supportive care.


    --  Hyponatremia: Monitor serum sodium levels throughout treatment. Correct
        for concurrent hyperglycemia and high serum paraprotein levels. Manage
        with dose interruption, reduction, or discontinuation, and supportive
        care.


    --  Serious Infection: Monitor for infection and treat promptly.


    --  Neurological Toxicity: Advise patients to refrain from driving and
        engaging in hazardous occupations or activities until neurological
        toxicity resolves. Optimize hydration status and concomitant medications
        to avoid dizziness or mental status changes.


    --  Embryo?Fetal Toxicity: Can cause fetal harm. Advise females of
        reproductive potential and males with a female partner of reproductive
        potential, of the potential risk to a fetus and use of effective
        contraception.
    --  Cataract: Cataracts may develop or progress. Treatment of cataracts
        usually requires surgical removal of the cataract.

Adverse Reactions

    --  The most common adverse reactions (>=20%) in patients with multiple
        myeloma who receive XVd are fatigue, nausea, decreased appetite,
        diarrhea, peripheral neuropathy, upper respiratory tract infection,
        decreased weight, cataract and vomiting. Grade 3?4 laboratory
        abnormalities (>=10%) are thrombocytopenia, lymphopenia,
        hypophosphatemia, anemia, hyponatremia and neutropenia. In the BOSTON
        trial, fatal adverse reactions occurred in 6% of patients within 30 days
        of last treatment. Serious adverse reactions occurred in 52% of
        patients. Treatment discontinuation rate due to adverse reactions was
        19%.


    --  The most common adverse reactions (>=20%) in patients with multiple
        myeloma who receive Xd are thrombocytopenia, fatigue, nausea, anemia,
        decreased appetite, decreased weight, diarrhea, vomiting, hyponatremia,
        neutropenia, leukopenia, constipation, dyspnea and upper respiratory
        tract infection. In the STORM trial, fatal adverse reactions occurred in
        9% of patients. Serious adverse reactions occurred in 58% of patients.
        Treatment discontinuation rate due to adverse reactions was 27%.
    --  The most common adverse reactions (incidence >=20%) in patients with
        DLBCL, excluding laboratory abnormalities, are fatigue, nausea,
        diarrhea, appetite decrease, weight decrease, constipation, vomiting,
        and pyrexia. Grade 3?4 laboratory abnormalities (>=15%) are
        thrombocytopenia, lymphopenia, neutropenia, anemia, and hyponatremia. In
        the SADAL trial, fatal adverse reactions occurred in 3.7% of patients
        within 30 days, and 5% of patients within 60 days of last treatment; the
        most frequent fatal adverse reactions was infection (4.5% of patients).
        Serious adverse reactions occurred in 46% of patients; the most frequent
        serious adverse reaction was infection (21% of patients).
        Discontinuation due to adverse reactions occurred in 17% of patients.

Use In Specific Populations
Lactation: Advise not to breastfeed.

For additional product information, including full prescribing information, please visit www.XPOVIO.com.

To report SUSPECTED ADVERSE REACTIONS, contact Karyopharm Therapeutics Inc. at 1?888?209?9326 or FDA at 1?800?FDA?1088 or www.fda.gov/medwatch.

About Karyopharm Therapeutics

Karyopharm Therapeutics Inc. (Nasdaq: KPTI) is a commercial-stage pharmaceutical company whose dedication to pioneering novel cancer therapies is fueled by a belief in the extraordinary strength and courage of patients with cancer. Since its founding, Karyopharm has been an industry leader in oral compounds that address nuclear export dysregulation, a fundamental mechanism of oncogenesis. Karyopharm's lead compound and first-in-class, oral exportin 1 (XPO1) inhibitor, XPOVIO® (selinexor), is approved in the U.S. and marketed by the Company in three oncology indications. It has also received regulatory approvals in various indications in a growing number of ex-U.S. territories and countries, including Europe and the United Kingdom (as NEXPOVIO®) and China. Karyopharm has a focused pipeline targeting indications in multiple high unmet need cancers, including in multiple myeloma, endometrial cancer, myelofibrosis, and diffuse large B-cell lymphoma (DLBCL). For more information about our people, science and pipeline, please visit www.karyopharm.com, and follow us on LinkedIn and on X at @Karyopharm.

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 ability of selinexor to treat patients with multiple myeloma, endometrial cancer, myelofibrosis, diffuse large B-cell lymphoma, and other diseases; and expectations with respect to the clinical development plans and potential regulatory submissions of selinexor. Such statements are subject to numerous important factors, risks and uncertainties, many of which are beyond Karyopharm's control, that may cause actual events or results to differ materially from Karyopharm's current expectations. For example, there can be no guarantee that Karyopharm will successfully commercialize XPOVIO or that any of Karyopharm's drug candidates, including selinexor, will successfully complete necessary 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 the development or commercialization of 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: the adoption of XPOVIO in the commercial marketplace, the timing and costs involved in commercializing XPOVIO or any of Karyopharm's drug candidates that receive regulatory approval; the ability to obtain and retain regulatory approval of XPOVIO or any of Karyopharm's drug candidates that receive regulatory approval; Karyopharm's results of clinical trials and preclinical trials, including subsequent analysis of existing data and new data received from ongoing and future trials; 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 trials; the ability of Karyopharm or its third party collaborators or successors in interest to fully perform their respective obligations under the applicable agreement and the potential future financial implications of such agreement; Karyopharm's ability to enroll patients in its clinical trials; unplanned cash requirements and expenditures; development or regulatory approval of drug candidates by Karyopharm's competitors for products or product candidates in which Karyopharm is currently commercializing or developing; the direct or indirect impact of the COVID-19 pandemic or any future pandemic on Karyopharm's business, results of operations and financial condition; and Karyopharm's ability to obtain, maintain and enforce patent and other intellectual property protection for any of its products or product candidates. These and other risks are described under the caption "Risk Factors" in Karyopharm's Annual Report on Form 10-K for the year ended December 31, 2023, which was filed with the Securities and Exchange Commission (SEC) on February 29, 2024, 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.

XPOVIO® and NEXPOVIO® are registered trademarks of Karyopharm Therapeutics Inc. Any other trademarks referred to in this release are the property of their respective owners.

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