Childhood Rhabdomyosarcoma

Elraglusib Demonstrated Anti-Tumor Activity with Two Ongoing Durable Complete Responses and ~62% Disease Control Rate in First 8 Patients with Relapsed/Refractory Ewing and Ewing-related SarcomasEnrollment Ongoing with Topline Data Anticipated in 1H 2025 CHICAGO and FORT WORTH, Texas, Sept. 09, 2024 (GLOBE NEWSWIRE) -- – Actuate Therapeutics, Inc. (NASDAQ: ACTU) (“Actuate” or the “Company”), a clinical-stage biopharmaceutical company focused on developing therapies for the treatment of high-impact, difficult-to-treat cancers through the inhibition of glycogen synthase kinase-3 beta (GSK-3β), provided an update on its Phase 1/2 trial of elraglusib in relapsed/refractory Ewing Sarcoma (r/r EWS). “Ewing sarcoma is a highly metastatic form of sarcoma and the second most prevalent primary malignant tumor in children and adolescents. There are currently no standardized second-line treatments for r/r EWS and the prognosis for these patients remains poor. There is an urgent need for new therapeutic strategies that combine novel targeted therapies with new mechanisms of action and existing chemotherapy regimens of established but limited efficacy,” said Daniel Schmitt, President & Chief Executive Officer of Actuate. “Elraglusib is one of the few novel targeted agents being pursued for the refractory EWS population and continues to show promise as a viable therapeutic option. Early clinical data suggest that the enhanced antitumor activity of chemotherapy observed in multiple preclinical refractory cancer models is translating well into clinical responses.” The ongoing Phase 1/2 Trial (NCT 04239092) is an open-label, multicenter study evaluating the safety and efficacy of elraglusib in pediatric patients with relapsed/refractory malignancies, including EWS and EWS-related pediatric small round cell sarcomas. To date, the study has enrolled 6 patients with relapsed/refractory EWS (>1 remission); one patient with a desmoplastic small round cell tumor (DSRCT), an ultra-rare, highly aggressive pediatric sarcoma; and one patient with a CIC rearrangement. All patients were treated with elraglusib in combination with cyclophosphamide/topotecan. Two patients with recurrent /refractory EWS are experiencing ongoing complete responses (CR), two patients achieved stable disease (SD), and two patients withdrew from the study before their tumor response could be assessed (Table 1). The patient with Desmoplastic Small-Round-Cell Tumor (DSRCT) achieved a partial response (PR) with a 52% reduction in tumor size but withdrew from the study and is now being followed for survival. Table 1. Summary of EWS and other small round cell sarcomas treated in Clinical Study 1902. PatientTumor TypeBest Overall ResponseOS (days)11EWSCR (CT and CMR by PET)Alive OS = 933 days2EWSCR (CMR by PET)Alive OS = 284 days3DSRCTPRAlive OS = 329 days4EWSSDOS = 177 days5EWSSDOS = 272 days6EWSNot Determined.Patient withdrew from the StudyAlive OS = 318 (LTFU)7EWSNot Determined.Patient withdrew from the StudyOS = 89 days8CIC-rearrangementNot Determined.Patient withdrew from the StudyN/A 1 As of most recent follow-up visits May – August 2024 “We are pleased to share our continued, promising progress with elraglusib in r/r EWS,” said Dr. Andrew Mazar, Actuate’s Scientific Co-Founder and Chief Operating Officer. “Although the sample size is small, we are encouraged by the disease stabilization and two ongoing complete responses observed, including one patient with an overall survival of over 2.5 years. These results are considered promising by clinical experts in pediatric oncology, particularly given the significant unmet medical need and lack of therapeutic alternatives in recurrent EWS, and support the continued development of elraglusib in this rare cancer patient population.” The 1902 study remains open only to patients with recurrent EWS, who will be treated with the combination of elraglusib with cyclophosphamide/topotecan. The study will enroll up to 12 total EWS patients to provide additional rationale for moving the elraglusib/cyclophosphamide/topotecan combination into a phase 2 study in patients with recurrent EWS. Actuate plans to meet with the FDA to discuss the design of a phase 2 study and options for accelerating the development path for elraglusib to commercial registration for the treatment of EWS. About Ewing Sarcoma Ewing sarcoma (EWS) is a highly metastatic form of sarcoma that ranks as the second most prevalent primary malignant tumor of childhood and adolescence originating in bone with a peak incidence at the age of 15 years. Approximately 25% of new EWS patients have metastatic disease when first diagnosed, which is the most significant predictor of poor survival. Treatment options for relapsed/refractory metastatic EWS are limited. Despite intensive therapy, recurrent EWS, whether local or with distant metastases, is almost always fatal. While the use of chemotherapy regimens in conjunction with surgery has resulted in the 5-year survival rate increasing from 59 to 78% in children and young adolescents, and from 20 to 60% in adults, to date, no standard treatment has been defined in the relapsed/refractory setting. About Actuate Therapeutics, Inc. Actuate is a clinical-stage biopharmaceutical company focused on developing therapies for the treatment of high-impact, difficult-to-treat cancers. Actuate’s lead investigational drug product, elraglusib (a novel GSK-3 inhibitor), targets molecular pathways in cancer that are involved in promoting tumor growth and resistance to conventional cancer drugs such as chemotherapy including several DDR pathways. For more information on the 1902 Study, please visit ClinicalTrial.gov and reference Identifier NCT04239092. Forward-Looking Statements This press release contains forward-looking statements about us, including our clinical trials and development plans, and our industry. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “ongoing,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” “would,” or the negative of these terms or other comparable terminology are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. All statements, other than statements related to present facts or current conditions or of historical facts, contained in this press release are forward-looking statements. Accordingly, these statements involve estimates, assumptions, substantial risks and uncertainties which could cause actual results to differ materially from those expressed in them, including but not limited to that clinical and preclinical drug development involves a lengthy and expensive process with uncertain timelines and outcomes, and results of prior preclinical studies and early clinical trials are not necessarily predictive of future results, and elraglusib may not achieve favorable results in clinical trials or preclinical studies or receive regulatory approval on a timely basis, if at all; that we may not successfully enroll additional patients or establish or advance plans for phase 2 or other development; that elraglusib could be associated with side effects, adverse events or other properties or safety risks, which could delay or preclude regulatory approval, cause us to suspend or discontinue clinical trials or result in other negative consequences; our reliance on third parties to conduct our non-clinical studies and our clinical trials; our reliance on third-party licensors and ability to preserve and protect our intellectual property rights; that we face significant competition from other biotechnology and pharmaceutical companies; and our ability to fund development activities. In addition, any forward-looking statements are qualified in their entirety by reference to the factors discussed under the heading “Risk Factors” in our final prospectus filed with the SEC on August 13, 2024 pursuant to Rule 424(b)(4) under the Securities Act with respect to our Registration Statement on Form S-1 (File No. 333-279734) and other filings with the SEC. You should assume that the information appearing in this press release is accurate as of its date only. Because the risk factors referred to above could cause actual results or outcomes to differ materially from those expressed in any forward-looking statements made by us or on our behalf, you should not place undue reliance on any forward-looking statements. Further, any forward-looking statement speaks only as of the date on which it is made. New factors emerge from time to time, and it is not possible for us to predict which factors will arise. In addition, we cannot assess the impact of each factor on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements. Unless legally required, we do not undertake any obligation to release publicly any revisions to such forward-looking statements to reflect events or circumstances after the date of this press release or to reflect the occurrence of unanticipated events. Investor Contact Mike MoyerManaging DirectorLifeSci Advisors, LLCmmoyer@lifesciadvisors.com

– Achieves Second Quarter 2024 Total Revenue of $42.8 Million and U.S. XPOVIO® (selinexor) Net Product Revenue of $28.0 Million; Positive Momentum ex-US with Continued Regulatory and Reimbursement Approvals – – Updated Clinical Results at ASCO Annual Meeting Showed Median Progression-Free Survival (PFS) of 28.4 Months in the TP53 Wild-Type Exploratory Subgroup and 39.5 Months in the Proficient Mismatched Repair Status (pMMR) TP53 Wild-Type Exploratory Subgroup from Phase 3 SIENDO Study of Selinexor Maintenance Treatment in Advanced/Recurrent Endometrial Cancer – – Pre-Clinical Data Presented at the June 2024 European Hematology Association Meeting Support Selinexor's Mechanism of Action Targeting Multiple Oncogenic Pathways beyond JAK/STAT and Builds on the Compelling Clinical Data in Myelofibrosis – – Completed Significant Refinancing Transactions and Amended Royalty Agreement with HealthCare Royalty Extending Vast Majority of Its Debt Maturities into 2028 and 2029, Well Beyond Expected Data Readouts and Potential Approvals from the Company's Three Phase 3 Trials, Strengthening the Company for its Next Stage of Growth – – Raises the Lower End of Full-Year 2024 Total Revenue Guidance to $145.0 Million to $160.0 Million and U.S. XPOVIO Net Product Revenue Guidance to $105.0 Million to $120.0 Million; Lowers Full Year 2024 R&D and SG&A Expense Guidance to $250.0 Million to $265.0 Million – NEWTON, Mass., Aug. 6, 2024 /PRNewswire/ -- Karyopharm Therapeutics Inc. (Nasdaq: KPTI), a commercial-stage pharmaceutical company pioneering novel cancer therapies, today reported financial results for the quarter ended June 30, 2024, and highlighted select corporate milestones and progress on its key clinical development programs. "We are pleased with the strength of our commercial performance with consecutive quarter-over-quarter growth in the highly competitive multiple myeloma marketplace and look forward to leveraging the foundation that we have built in this indication to serve additional patients. Looking ahead with our improved capital structure following our debt refinancing and disciplined expense management, we are strongly positioned for our next stage of growth, to redefine the standard of care for patients with myelofibrosis and endometrial cancer, driven by selinexor's growing body of compelling clinical and preclinical data in these indications," said Richard Paulson, President and Chief Executive Officer of Karyopharm. Second Quarter 2024 and Recent Highlights XPOVIO Commercial Performance Achieved U.S. net product revenue of $28.0 million for the second quarter of 2024, compared to $26.0 million for the first quarter of 2024 and $28.5 million for the second quarter of 2023. XPOVIO net product revenue was supported by quarter-over-quarter growth in both new patient starts and refills. Continued quarter-over-quarter growth with > 10% growth in the community setting, which represents ~60% of overall net product revenues. In the academic setting, demand for XPOVIO was consistent quarter-over-quarter amidst ongoing competitive pressures, driven by the expanding use of XPOVIO immediately preceding and following T-cell therapies in later lines. The vast majority of XPOVIO new patient mix continues to be in the second to fourth lines of therapy. Continued global momentum in the second quarter of 2024 with favorable reimbursement decisions in the United Kingdom and South Korea, and additional regulatory approvals in relapsed/refractory (R/R) DLBCL in mainland China and R/R multiple myeloma in multiple international markets. Research and Development (R&D) Highlights Myelofibrosis Pre-clinical data were presented on the mechanism of action for XPO1 inhibition in myelofibrosis targeting multiple oncogenic pathways beyond JAK/STAT, including inhibition of NF-κB-driven proinflammatory cytokines and p53-mediated cell cycle regulation, at the June 2024 European Hematology Association meeting. These data suggest that XPO1 may be fundamental in myelofibrosis, providing the mechanistic rationale for both monotherapy as well as additive, if not synergistic, activity in combination with ruxolitinib, which we believe further supports the promising clinical results, including durable spleen volume reduction and symptom improvement, observed to date from the Phase 1 trial. Pivotal SENTRY Phase 3 trial of selinexor in combination with ruxolitinib in JAK-naive myelofibrosis continues to enroll with strong momentum, supported by high interest from investigators and minimal competition from other therapies in the JAK-naïve setting; expected top-line data readout on track for 2H 2025. Endometrial Cancer Long-term follow-up data from a pre-specified exploratory subgroup analysis of patients with advanced or recurrent TP53 wild-type endometrial cancer from the SIENDO study (NCT03555422) were presented at "ASCO Plenary Series: Rapid Abstract Updates" oral session at the ASCO Annual Meeting in June 2024. In the exploratory subgroup analysis from the Phase 3 SIENDO Study, 113 patients with TP53 wild-type advanced/recurrent endometrial cancer were randomized to receive selinexor (n=77) vs placebo (n=36) as maintenance therapy after 1L platinum-based chemotherapy. As of the April 1, 2024 data cut-off date, and a median duration of follow-up of 36.8 months, selinexor-treated patients had a median PFS of 28.4 months compared to 5.2 months for patients receiving placebo. In selinexor-treated patients with TP53 wild-type/pMMR and TP53 wild-type/dMMR endometrial cancer, the median PFS was 39.5 months and 13.1 months compared to 4.9 months and 3.7 months in those treated with placebo, respectively. Although immature, overall survival (OS) in the TP53 wild-type subgroup was promising, with a hazard ratio of 0.65; median OS for selinexor has not been reached as of the data cut-off date. No new safety signals were identified as of the data cut-off date of April 1, 2024. The most common treatment-emergent adverse events in selinexor treated TP53 wild-type patients were nausea (90%), vomiting (60%) and diarrhea (45%), the majority of which were grades 1-2. The updated SIENDO analysis also highlighted findings from an exploratory quality-adjusted time without symptoms or toxicity analysis (Q-TWiST) used to assess quality and toxicity-adjusted PFS. The findings showed the restricted mean Q-TWiST for selinexor to be 26 months compared to 15 months for placebo, resulting in a difference of nearly 11 months. Pivotal XPORT-EC-042 Phase 3 trial in TP53 wild-type endometrial cancer is now expected to read-out top-line data in early 2026, primarily due to higher-than-expected screen failure rates. Multiple Myeloma Updated clinical data on SPd (selinexor in combination with pomalidomide and dexamethasone) regimen from STOMP and MM-028 trials were published in the Frontiers of Oncology Journal in May 2024. Both the Phase 1b/2 Selinexor and Backbone Treatments of Myeloma Patients (STOMP) trial (NCT02343042) and the Phase 2b XPORT-MM-028 (NCT04414475) trials are evaluating multiple selinexor combinations, including SPd, in patients with relapsed or refractory multiple myeloma (RRMM). The updated results for SPd 40 mg from these studies showed a median PFS of 18.4 months and a manageable safety profile with no new safety signals. Pivotal XPORT-MM-031 (EMN29) Phase 3 trial, an oral combination of selinexor 40 mg, pomalidomide and dexamethasone in patients with previously treated multiple myeloma, is enrolling patients at a lower rate than expected in an increasingly global competitive clinical trial environment targeting a similar patient population. Given this evolving environment and the positive SPd 40 mg PFS data published from the STOMP and MM-028 trials, Karyopharm intends to work with the trial's sponsor, the European Myeloma Network, to amend certain aspects of the design for this trial, including a reduction in the number of patients that are targeted for enrollment, and the statistical plan. With these updates, Karyopharm expects top-line data readout in 1H 2025; there remains a potential to seek regulatory approval pending the outcome of the study results. KPT-9274 (Padnarsertib) KPT-9274, a first-in-class, oral small molecule and a dual inhibitor of PAK4 and NAMPT that was discovered at Karyopharm, was granted two Rare Pediatric Disease Designations (RPDD) by the U.S. Food and Drug Administration (FDA) for the treatment of Rhabdomyosarcoma (RMS) and for the treatment of Ewing sarcoma (EWS) in June 2024. The FDA further granted KPT-9274 two Orphan Drug Designations in July 2024 for the treatment of soft tissue sarcoma, which includes RMS, and for the treatment of EWS. RMS and EWS are rare cancers of the bone or soft tissue, primarily diagnosed in pediatric patients, with poor survival outcomes and high unmet need for new therapies. KPT-9274 showed tumor regressions and decreased metastatic properties in pediatric RMS and EWS pre-clinical models. Karyopharm is evaluating out-licensing and/or partnership opportunities for further advancement of this program. Financing Transactions and 2024 Financial Outlook In May 2024, the Company completed certain financing transactions which extended the vast majority of its debt maturities into 2028 and 2029 and amended its royalty agreement with HealthCare Royalty, further strengthening its balance sheet. Based on its current operating plans, Karyopharm has updated its guidance for full year 2024 as follows: Total revenue to be in the range of $145.0 million to $160.0 million as compared to initial guidance of $140.0 million to $160.0 million. Total revenue consists of U.S. XPOVIO net product revenue and license, royalty and milestone revenue earned from partners. U.S. XPOVIO net product revenue to be in the range of $105.0 million to $120.0 million as compared to initial guidance of $100.0 million to $120.0 million. R&D and selling, general and administrative (SG&A) expenses to be in the range of $250.0 million to $265.0 million, which includes approximately $20.0 million estimated non-cash stock-based compensation expense, as compared to initial guidance of $260.0 million to $280.0 million including $20.0 million to $25.0 million of estimated non-cash stock-based compensation expense. The Company expects that its existing cash, cash equivalents and investments, and the revenue it expects to generate from XPOVIO net product sales, as well as revenue generated from its license agreements, will be sufficient to fund its planned operations into the first quarter of 20261 aided by ongoing disciplined expense management and initiated cost saving measures. 1 Excluding re-payment of $24.5 million aggregate principal amount of the Company's remaining senior convertible notes due 2025 and $25.0 million minimum liquidity covenant under the senior secured term loan due 2028. Second Quarter 2024 Financial Results Total revenue: Total revenue for the second quarter of 2024 was $42.8 million, compared to $37.6 million for the second quarter of 2023. Net product revenue: Net product revenue for the second quarter of 2024 was $28.0 million, compared to $28.5 million for the second quarter of 2023. License and other revenue: License and other revenue for the second quarter of 2024 was $14.8 million, compared to $9.1 million for the second quarter of 2023. The increase was primarily due to $4.0 million of milestone-related revenue recognized from Menarini in 2024 and a $2.3 million increase in revenue for the reimbursement of development-related expenses from Menarini due to an increase in the corresponding expenses. Cost of sales: Cost of sales for the second quarter of 2024 was $1.5 million, compared to $1.2 million for the second quarter of 2023. Cost of sales reflects the costs of XPOVIO units sold and the costs of products sold to our partners. R&D expenses: R&D expenses for the second quarter of 2024 were $38.4 million, compared to $31.5 million for the second quarter of 2023. The increase was primarily due to an increase in clinical trial and related costs, related mainly to increased activity in our ongoing pivotal Phase 3 trials in myelofibrosis and multiple myeloma, including increased purchases of comparator drugs. SG&A expenses: SG&A expenses for the second quarter of 2024 were $31.1 million, compared to $34.5 million for the second quarter of 2023. The decrease was primarily due to our ongoing cost reduction initiatives and lower headcount. Interest income: Interest income for the second quarter of 2024 was $1.9 million, compared to $2.8 million for the second quarter of 2023. Interest expense: Interest expense for the second quarter of 2024 was $8.9 million, compared to $5.8 million for the second quarter of 2023. The increase in interest expense was due to the Company's new term loan and new secured convertible senior notes. Gain on extinguishment of debt and other income: The Company recognized a non-cash gain on extinguishment of debt of $44.7 million and other income of $14.3 million during the second quarter of 2024, which related to the refinancing transactions that were completed during the second quarter of 2024. Net income (loss): Karyopharm reported net income of $23.8 million, or $0.15 income per basic share and $0.20 loss per diluted share, for the second quarter of 2024, compared to a net loss of $32.6 million, or $0.29 loss per basic and diluted share, for the second quarter of 2023. Cash position: Cash, cash equivalents, restricted cash and investments as of June 30, 2024 totaled $152.5 million, compared to $192.4 million as of December 31, 2023. Conference Call Information Karyopharm will host a conference call today, August 6, 2024, at 8:00 a.m. Eastern Time, to discuss the second quarter 2024 financial results and provide business highlights. To access the conference call, please dial (800) 836-8184 (local) or (646) 357-8785 (international) at least 10 minutes prior to the start time and ask to be joined into the Karyopharm Therapeutics call. A live audio webcast of the call, along with accompanying slides, will be available under "Events & Presentations" in the Investor section of the Company's website. An archived webcast will be available on the Company's website approximately two hours after the event. References: 1 Excluding re-payment $24.5 million aggregate principal amount of the Company's remaining senior convertible notes due 2025 and $25.0 million minimum liquidity covenant under the senior secured term loan due 2028. 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 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, China, South Korea and Israel, 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: [email protected] 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 . To report SUSPECTED ADVERSE REACTIONS, contact Karyopharm Therapeutics Inc. at 1‐888‐209‐9326 or FDA at 1‐800‐FDA‐1088 or . 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 , 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 Karyopharm's guidance on its 2024 total revenue, 2024 U.S. net product revenue and 2024 R&D and SG&A expenses; Karyopharm's expected cash runway; expectations with respect to commercialization efforts; 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 Quarterly Report on Form 10-Q for the quarter ended March 31, 2024, which was filed with the Securities and Exchange Commission (SEC) on May 8, 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. SOURCE Karyopharm Therapeutics Inc.

Administration of azenosertib combined with gemcitabine was well tolerated and resulted in clinically meaningful increase in event-free survival compared to historical comparators Results support further evaluation of azenosertib combined with gemcitabine in relapsed or refractory osteosarcoma through an investigator-initiated Phase 2 trial NEW YORK and SAN DIEGO, May 23, 2024 (GLOBE NEWSWIRE) -- Zentalis® Pharmaceuticals, Inc. (Nasdaq: ZNTL), a clinical-stage biopharmaceutical company discovering and developing clinically differentiated small molecule therapeutics targeting fundamental biological pathways of cancers, today announced the presentation of final results from a Phase 1 trial of azenosertib and gemcitabine in relapsed or refractory (R/R) osteosarcoma at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. “We are pleased to report the final results from our Phase 1 trial evaluating azenosertib administered with gemcitabine in patients with relapsed or refractory osteosarcoma,” said Kimberly Blackwell, M.D., Chief Executive Officer of Zentalis. “Azenosertib was well tolerated and clinically active in combination with gemcitabine and a go-forward dose was identified. Most importantly, the event-free survival results demonstrate a tripling in the proportion of patients without progression or death at 18 weeks compared with historical control patients. These results support studying the combination in patients facing this aggressive cancer, which we expect will occur in an upcoming investigator-initiated Phase 2 trial. We also look forward to presenting additional data on azenosertib in gynecological malignancies later this year as our development path continues to progress on track.” Data Highlights and Conclusions: 31 patients were enrolled in the study, of which 31 were evaluable for safety, 29 were evaluable for dose-limiting toxicities and 28 were evaluable for efficacy. The median age was 27 (range 12-76) and 21 patients (68%) were ≤39 years old. Patients received a median of 3 (range 1-9) prior therapies, including 10 patients (32%) who had previous treatment with gemcitabine.The 18-week event-free survival rate (EFS; time from treatment initiation until disease progression or death due to any cause) was 39% (11/28) across all dose levels. The EFS observed in the study compares favorably to historical cohorts with a similar patient population where a 16-week EFS of ~12% has been reported1.The maximum tolerated dose (MTD) of azenosertib was determined to be 150 mg daily on a 5:2 schedule (5 days on, 2 days off) + gemcitabine 800 mg/m2.At the MTD, the most frequent grade ≥3 adverse events (≥20%) included thrombocytopenia and lymphopenia (33% each); there were no grade 4 thrombocytopenia events or instances of febrile neutropenia at the MTD.Data support further investigation of azenosertib administered in combination with gemcitabine in patients with R/R osteosarcoma in an upcoming investigator-initiated Phase 2 trial. 1 Lagmay JP, et al. J Clin Oncol. 2016;34(25):3031-3038. “Historically, the management of relapsed and/or refractory osteosarcoma has been limited to cytotoxic chemotherapy and only recently, tyrosine kinase inhibitors, with suboptimal outcomes,” said Viswatej Avutu, M.D., Sarcoma Medical Oncology Service and Pediatric Sarcoma Team, Memorial Sloan Kettering Cancer Center, New York, NY. “Azenosertib provides promise as a novel class of drugs and offers hope for a well-tolerated and potentially efficacious treatment option that is desperately needed.” Study DesignPhase 1 dose-finding study (NCT04833582) assessed azenosertib administered in combination with gemcitabine in patients ≥12 years of age. The primary endpoint was the incidence and severity of dose-limiting toxicities. Secondary endpoints included the incidence and severity of adverse events and EFS at 18 weeks per RECIST v1.1. Poster Presentation Details:The full abstract (#11525) is available here on the ASCO Congress portal.Title: Phase 1 Results of the WEE1 Inhibitor, Azenosertib, in Combination With Gemcitabine in Adult and Pediatric Patients With Relapsed or Refractory Osteosarcoma.Presenter: Dr. Viswatej Avutu, Sarcoma Medical Oncology Service and Pediatric Sarcoma Team, Memorial Sloan Kettering Cancer Center, New York, NYSession Title: Poster Session – SarcomaSession Date and Time: June 1, 2024. 1:30-4:30 PM CDT About AzenosertibAzenosertib is a novel, selective, and orally bioavailable inhibitor of WEE1 currently being evaluated as a monotherapy and combination clinical studies in ovarian cancer and additional tumor types. WEE1 acts as a master regulator of the G1-S and G2-M cell cycle checkpoints, through negative regulation of both CDK1 and CDK2, to prevent replication of cells with damaged DNA. By inhibiting WEE1, azenosertib enables cell cycle progression, despite high levels of DNA damage, thereby resulting in the accumulation of DNA damage and leading to mitotic catastrophe and cancer cell death. About Zentalis Pharmaceuticals Zentalis® Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company discovering and developing clinically differentiated small molecule therapeutics targeting fundamental biological pathways of cancers. The Company’s lead product candidate, azenosertib (ZN-c3), is a potentially first-in-class and best-in-class WEE1 inhibitor for advanced solid tumors and hematologic malignancies. Azenosertib is being evaluated as a monotherapy and in combination across multiple clinical trials and has broad franchise potential. In clinical trials, azenosertib has been well tolerated and has demonstrated anti-tumor activity as a single agent across multiple tumor types and in combination with several chemotherapy backbones. As part of its azenosertib clinical development program, the Company is exploring enrichment strategies targeting tumors of high genomic instability, such as Cyclin E1 positive tumors, homologous recombination deficient tumors and tumors with oncogenic driver mutations. The Company is also leveraging its extensive experience and capabilities across cancer biology and medicinal chemistry to advance its research on protein degraders. Zentalis has operations in both New York and San Diego. For more information, please visit www.zentalis.com. Follow Zentalis on X/Twitter at @ZentalisP and on LinkedIn at www.linkedin.com/company/zentalis-pharmaceuticals. ZENTALIS® and its associated logo are trademarks of Zentalis and/or its affiliates. All website addresses and other links in this press release are for information only and are not intended to be an active link or to incorporate any website or other information into this press release. Forward-Looking StatementsThis press release contains forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including statements regarding our plans to present final results from a Phase 1 trial of azenosertib and gemcitabine in relapsed/refractory osteosarcoma at the 2024 American Society of Clinical Oncology Annual Meeting in Chicago; plans for an investigator-initiated Phase 2 trial evaluating azenosertib combined with gemcitabine in R/R osteosarcoma; our plans to present additional data on azenosertib in gynecological malignancies later in 2024; the potential for azenosertib to be first-in-class and best-in-class; the broad franchise potential of azenosertib; our plans with respect to the development of our product candidates, including azenosertib; and the potential benefits of azenosertib, including the potential benefits of the design thereof, the value potential of the asset, and the potential to improve outcomes for patients. The terms “continue,” “expect,” “look forward,” “on track,” “potential,” “promise,” “upcoming,” “will,” and similar references are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our limited operating history, which may make it difficult to evaluate our current business and predict our future success and viability; we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; our plans, including the costs thereof, of development of any diagnostic tools; our substantial dependence on the success of our lead product candidates; the outcome of preclinical testing and early trials may not be predictive of the success of later clinical trials; failure to identify additional product candidates and develop or commercialize marketable products; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the regulatory approval process or ongoing regulatory obligations; failure to obtain U.S. or international marketing approval; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; effects of significant competition; the possibility of system failures or security breaches; risks relating to intellectual property; our ability to attract, retain and motivate qualified personnel, and risks relating to management transitions; significant costs as a result of operating as a public company; and the other important factors discussed under the caption “Risk Factors” in our most recently filed periodic report on Form 10-K or 10-Q and subsequent filings with the U.S. Securities and Exchange Commission (SEC) and our other filings with the SEC. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. Contact:Elizabeth Pingpank Hickinehickin@zentalis.com860.463.0469