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– Planned August sNDA Submission for Selinexor in Combination with Ruxolitinib in Myelofibrosis under the Accelerated Approval Pathway Remains on Track – – Planned sNDA for Selinexor plus Ruxolitinib Supported by Phase 3 SENTRY Results Presented at ASCO and EHA and Published in the Journal of Clinical Oncology; Potential to Become the First Approved Combination Therapy for Patients with Myelofibrosis – – Total Revenue was $33.4 Million, and U.S. XPOVIO® (selinexor) Net Product Revenue was $30.8 Million for the Second Quarter of 2026 – – Company Reaffirms Full-Year 2026 Total Revenue Guidance of $130 Million to $150 Million Including U.S. XPOVIO Net Product Revenue Guidance of $115 Million to $130 Million – – Conference Call Scheduled for Today at 8:00 a.m. ET – NEWTON, Mass., Aug. 13, 2026 /PRNewswire/ -- Karyopharm Therapeutics Inc. (Nasdaq: KPTI), a commercial-stage pharmaceutical company pioneering novel cancer therapies, today reported financial results for the second quarter of 2026 and provided an update on the Company's myelofibrosis program. Following continued constructive engagement with the U.S. Food and Drug Administration (FDA), the Company remains on track to submit its planned supplemental New Drug Application (sNDA) in August under the Accelerated Approval pathway for selinexor in combination with ruxolitinib for patients with myelofibrosis. Karyopharm intends to request Priority Review at the time of submission. "Our planned submission under the Accelerated Approval pathway represents the beginning of an important new chapter for Karyopharm and an important milestone for the myelofibrosis community," said Richard Paulson, President and Chief Executive Officer of Karyopharm. "If approved, selinexor plus ruxolitinib would become the first approved combination therapy for patients with myelofibrosis, introducing a novel therapeutic mechanism for the treatment of this disease within the multi-billion-dollar U.S. marketplace. Our planned submission follows productive engagements with the FDA and reflects the speed, focus, urgency and extraordinary commitment of our teams. We look forward to continuing to work closely with the FDA." "Together with the continued scientific engagement we are seeing across the myelofibrosis community, we believe the strength and consistency of the SENTRY data reinforce the potential of selinexor to fundamentally change the treatment of patients with myelofibrosis," added Mr. Paulson. Second Quarter 2026 and Recent Company Highlights XPOVIO Commercial Performance U.S. net product revenue was $30.8 million for the quarter ended June 30, 2026 compared to $29.7 million for the quarter ended June 30, 2025. Demand for XPOVIO was relatively consistent in the second quarter of 2026 compared to the second quarter of 2025, amidst a highly competitive commercial landscape. The community setting continued to represent approximately 60% of net product revenue. Expanded global patient access for selinexor is translating into growth in royalty revenue from Menarini, Antengene and other international partners. Royalty revenue increased to $2.5 million in the second quarter of 2026 compared to $1.6 million in the second quarter of 2025, with selinexor approved in more than 50 ex-U.S. countries and territories. Research and Development (R&D) Highlights Myelofibrosis Planned sNDA submission under the Accelerated Approval pathway following multiple, productive engagements with the FDA, including Type B and Type C meetings, and received written feedback from the FDA that spleen volume reduction ≥ 35% (SVR35) appears to qualify as a reasonably likely surrogate endpoint (RLSE) to predict overall survival and can be used to support an sNDA submission. Results from the Phase 3 SENTRY trial (NCT04562389) in myelofibrosis were presented in a Late-Breaking Oral Presentation at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and simultaneously published in the peer-reviewed Journal of Clinical Oncology demonstrating rapid, deep and sustained spleen responses, promising overall survival findings and evidence consistent with potential disease modification. Additional analyses presented during a Late-Breaking Oral Presentation at the European Hematology Association (EHA) Congress—where the abstract was selected as one of the six best abstracts presented at the meeting—provided additional evidence supporting SVR35 as a potential predictor of overall survival. The Company continues active scientific exchange with investigators and treating physicians following the ASCO and EHA presentations and publication of the SENTRY results in the Journal of Clinical Oncology. Continue enrolling patients into the 40 mg cohort of the Phase 2 SENTRY-2 trial (NCT05980806), following completion of enrollment of the 60 mg cohort (n=29) earlier this year. Endometrial Cancer Announced topline results from the Phase 3 XPORT-EC-042 trial (NCT05611931), evaluating selinexor as a maintenance-only therapy compared to placebo in adult patients with TP53 wild-type advanced or recurrent endometrial cancer. The trial did not meet its primary endpoint of progression-free survival. A trend favoring the selinexor arm was observed in the modified intent to treat (mITT) population (n=236), with a median PFS of 12.75 months in the selinexor arm compared to 7.43 months in the placebo arm (hazard ratio=0.76 [95% CI: 0.51, 1.12]; one-sided p-value=0.0791). The safety and tolerability profile of selinexor was consistent with its established safety profile, with no new safety signals observed. Following the Phase 3 topline results, the Company has prioritized future investment toward its myelofibrosis and multiple myeloma programs while continuing long-term follow-up of patients enrolled in XPORT-EC-042. Multiple Myeloma Patients enrolled in the Phase 3 XPORT-MM-031 trial (EMN29; NCT05028348) continue to be followed for progression-free survival events contributing towards the primary endpoint. The trial is being conducted in collaboration with the European Myeloma Network and is evaluating the all-oral combination of selinexor 40 mg, pomalidomide and dexamethasone (SPd40) in patients with previously treated multiple myeloma who received an anti-CD38 as their immediate prior line of therapy. Anticipated Catalysts and Operational Objectives Myelofibrosis FDA acceptance of the Company's planned August sNDA submission for selinexor in myelofibrosis, including potential Priority Review designation. Planned advancement of global regulatory activities with the Company's partners to support potential regulatory submissions outside the United States. Potential inclusion of selinexor plus ruxolitinib in relevant compendia in the second half of 2026. Topline data from the Phase 2 SENTRY-2 60 mg cohort expected in the second half of 2026. Multiple Myeloma Maintain the Company's commercial foundation in the increasingly competitive multiple myeloma marketplace and drive increased XPOVIO revenues. Support global launches by the Company's partners following regulatory and reimbursement approvals for selinexor in ex-U.S. countries and territories. Announce topline data from the event-driven Phase 3 XPORT-MM-031 (EMN29) trial expected in the second half of 2026. 2026 Financial Outlook Based on its current operating plans, Karyopharm expects the following for full year 2026: Total revenue to be in the range of $130 million to $150 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 $115 million to $130 million. R&D and selling, general and administrative (SG&A) expenses to be in the range of $230 million to $245 million, excluding certain one-time costs that the Company may incur associated with its endometrial cancer program and evaluating financing opportunities and/or strategic transactions. The Company, together with its financial advisor Centerview Partners and other advisors, is actively evaluating a range of financing opportunities and strategic alternatives with the objective of maximizing both near- and long-term value for stakeholders while preserving strategic flexibility as it advances its myelofibrosis program. The Company expects its existing liquidity, including cash, cash equivalents and investments, together with anticipated cash flow from net product revenue and license and other revenue, to fund its current operating plans into September 2026. As discussed above, the Company is actively evaluating a range of financing opportunities and strategic alternatives with the objective of extending its cash runway, preserving strategic flexibility and maximizing long-term shareholder value as it advances its myelofibrosis program. On September 10, 2026, a $15.8 million principal payment is due under the Company's senior secured term loan facility. If that payment is made without additional financing or a waiver from the Company's lenders, the Company expects its cash, cash equivalents and investments would fall below its $10.0 million minimum liquidity covenant, which would constitute an event of default under the term loan. Second Quarter 2026 Financial Results Total revenue: Total revenue for the second quarter of 2026 was $33.4 million, compared to $37.9 million for the second quarter of 2025. Net product revenue: Net product revenue was $30.8 million for the second quarter of 2026, compared to $29.7 million for the second quarter of 2025. Net product revenue for the three months ended June 30, 2026, reflects relatively consistent demand for XPOVIO in an increasingly competitive multiple myeloma marketplace. License and other revenue: License and other revenue was $2.6 million for the second quarter of 2026, compared to $8.2 million for the second quarter of 2025. The decrease was primarily attributable to a $6.5 million reduction in development-related reimbursement revenue from Menarini following the expiration, on December 31, 2025, of Menarini's annual $15.0 million research and development obligation. Cost of sales: Cost of sales was $1.1 million for both the second quarter of 2026 and 2025. R&D expenses: R&D expenses were $29.0 million for the second quarter of 2026, compared to $32.8 million for the second quarter of 2025. The decrease was driven by our continued prioritization, focus, and efficient spending while advancing our late-stage programs, with our Phase 3 trials having completed full enrollment. SG&A expenses: SG&A expenses were $25.9 million for the second quarter of 2026, compared to $28.5 million for the second quarter of 2025. The decrease was primarily driven by proactive cost containment while maintaining disciplined alignment of pre-launch investments with clinical and regulatory milestones. Loss from operations: Loss from operations was $22.5 million for the second quarter of 2026, compared to $24.4 million for the second quarter of 2025. The improvement reflects the benefit of cost reduction initiatives implemented over the past several years. Interest income: Interest income was $0.7 million for the second quarter of 2026, compared to $0.6 million for the second quarter of 2025. Interest expense: Interest expense was $13.1 million for the second quarter of 2026, compared to $11.2 million for the second quarter of 2025. The increase reflects higher outstanding debt and higher interest rates following the Company's financing transactions executed in October 2025. Other expense, net: Other expense, net was $32.1 million in the second quarter of 2026, compared to $2.2 million in the second quarter of 2025. This expense is primarily non-operational and non-cash due to fair value of embedded derivatives and liability-classified common stock warrants related to the refinancing transactions completed in the second quarter of 2024 and the fourth quarter of 2025. The fair value of these instruments is remeasured each reporting period and is impacted by various inputs, including changes in the Company's share price. Net loss: Net loss was $67.0 million, or $2.32 per basic and diluted share, for the second quarter of 2026, compared to $37.3 million, or $4.32 per basic and diluted share, for the second quarter of 2025. Net loss for the second quarter of 2026 reflects an operating loss of $22.5 million and $44.5 million in non-operating expense comprised of $13.1 million of interest expense and $32.1 million of other expense partially offset by $0.7 million of interest income. Cash position: Cash, cash equivalents, restricted cash and investments as of June 30, 2026, totaled $65.4 million. Conference Call Information Karyopharm will host a conference call today, August 13, 2026, at 8:00 a.m. Eastern Time, to discuss the second quarter 2026 financial results, the financial outlook for 2026 and to provide other business updates. 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. About the Phase 3 SENTRY Trial SENTRY (XPORT-MF-034; NCT04562389) is a Phase 3 clinical trial evaluating a once-weekly dose of 60 mg of selinexor in combination with ruxolitinib compared to placebo plus ruxolitinib in JAKi-naïve myelofibrosis patients with platelet counts >100 x 109/L (N=353). Patients were randomized 2-to-1 to the selinexor arm. The co-primary endpoints for this trial are spleen volume reduction ≥ 35% (SVR35) at week 24 and the average change in absolute total symptom score (Abs-TSS) over 24 weeks relative to baseline. The results from the Phase 3 SENTRY trial were presented at the 2026 American Society of Clinical Oncology Annual Meeting and were simultaneously published in the peer-reviewed Journal of Clinical Oncology. In addition, the results were presented at the 2026 European Hematology Association Congress, where the presentation was recognized as one of the six best abstracts at the meeting. About Myelofibrosis Myelofibrosis is a rare blood cancer that affects approximately 20,000 patients in the United States and 17,000 patients in the European Union1. The disease causes bone marrow fibrosis (scarring in the bone marrow), which makes it difficult for the bone marrow to make healthy blood cells, splenomegaly (enlarged spleen), progressive anemia which often leads to symptoms like fatigue and weakness, and other disease associated symptoms including abdominal discomfort, pain under the left ribs, early satiety, night sweats and bone pain. The only approved class of therapies to treat myelofibrosis are JAK inhibitors, including ruxolitinib. About the Phase 3 XPORT-EC-042 Trial EC-042 (XPORT-EC-042; ENGOT-EN20; GOG-3083; NCT05611931) is a global, Phase 3, randomized, double-blind, placebo-controlled clinical trial evaluating selinexor as a maintenance-only therapy following chemotherapy or chemotherapy plus a checkpoint inhibitor in patients with TP53 wild-type advanced or recurrent endometrial cancer (N=257). Patients were randomized 1:1 to receive either a 60 mg, once-weekly, administration of oral selinexor or placebo until disease progression. The trial includes two patient populations, for which the primary endpoint of progression-free survival was tested sequentially: 1) a modified intent to treat population (mITT) that includes patients with either, a) TP53 wild-type tumors with proficient mismatch repair status (pMMR); or, b) TP53 wild-type tumors with deficient mismatch repair status (dMMR), who are medically ineligible to receive checkpoint inhibitors; and, 2) the trial's original intent to treat (ITT) population, which includes all patients enrolled in the trial whose tumors are TP53 wild-type, regardless of MMR status. Overall survival is a key secondary endpoint. The mITT population enrolled 236 patients. As of the data cut-off, 106 progression-free survival events as assessed by the investigator had been observed in the mITT population. In connection with the EC-042 trial, Karyopharm entered into a global collaboration with Foundation Medicine, Inc. to develop FoundationOne®CDx, a tissue-based comprehensive genomic profiling test to identify and enroll patients whose tumors are TP53 wild-type. The trial is being conducted in collaboration with the European Network of Gynaecological Oncological Trial groups (ENGOT) and the GOG Foundation, Inc. About Endometrial Cancer Endometrial cancer (EC) is the most common gynecologic malignancy in the U.S.1 In 2026, approximately 68,000 uterine cancers (predominantly endometrial) are expected to be diagnosed, with approximately 14,000 deaths.1 Worldwide there were about 420,368 cases with 97,723 deaths in 2022.2 Both incidence and mortality have continued to rise.3,4 Key risk factors include obesity, type 2 diabetes, high-fat diets, tamoxifen or oral estrogen use, and delayed menopause.5 TP53 is a well-recognized prognostic marker for EC; >50% of advanced or recurrent EC tumors are TP53wt (gene for tumor protein P53; wild-type), and ~40%-55% are both TP53wt and mismatch repair-proficient (pMMR).6-8 While immune checkpoint inhibitors have shown benefit in patients with mismatch repair–deficient (dMMR) and pMMR, the magnitude of benefit is greater for patients with dMMR tumors versus pMMR tumors.9-10 There remains an unmet need for targeted therapies for patients with pMMR EC.11 About XPOVIO® (selinexor) XPOVIO is a first-in-class, oral exportin 1 (XPO1) inhibitor compound for the treatment of cancer. XPOVIO functions by selectively binding to and inhibiting the nuclear export protein XPO1. XPOVIO is approved and marketed by Karyopharm in the U.S. in multiple oncology indications, including: (i) in combination with VELCADE® (bortezomib) and dexamethasone (XVd) in adult patients with multiple myeloma after at least one prior therapy; and (ii) in combination with dexamethasone in adult patients with heavily pre-treated multiple myeloma. XPOVIO® (also known as NEXPOVIO® in certain countries) has received regulatory approvals in various indications in a growing number of ex-U.S. territories and countries, including but not limited to the European Union, the United Kingdom, Mainland China, Taiwan, Hong Kong, Australia, South Korea, Singapore, Israel, and Canada. XPOVIO®/NEXPOVIO® is marketed in these respective ex-U.S. territories by Karyopharm's partners: Antengene, Menarini, Neopharm, and FORUS. Selinexor is also being investigated in several other mid- and late-stage clinical trials across multiple high-unmet need cancer indications. 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). 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%. 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 is a commercial-stage pharmaceutical company pioneering the science of nuclear export inhibition to develop differentiated therapies for patients with cancer. The Company's lead therapy, XPOVIO® (selinexor), is a first-in-class inhibitor of exportin 1 (XPO1). XPOVIO is marketed by the Company in the U.S. for adults with relapsed or refractory multiple myeloma and is approved as XPOVIO or NEXPOVIO® in more than 50 ex-U.S. countries and territories. Building on its leadership in XPO1 biology, Karyopharm is advancing selinexor's potential in hematological cancers, including in myelofibrosis. The Company is also exploring opportunities to evaluate XPO1 inhibition across myeloproliferative neoplasms using next-generation compounds, including eltanexor. Headquartered in Newton, Massachusetts, Karyopharm has an established, efficient, and scalable commercial infrastructure to bring novel therapeutic options to patients with cancer. For more information, visit and follow Karyopharm 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 2026 total revenue, 2026 U.S. net product revenue and 2026 R&D and SG&A expenses; expected cash runway and liquidity, including its ability to make scheduled debt service payments and maintain compliance with its minimum liquidity covenant; Karyopharm's expectations with respect to the timing and submission of a potential sNDA for selinexor in combination with ruxolitinib in myelofibrosis; Karyopharm's ongoing engagement with the FDA; the potential availability of the accelerated approval pathway; whether long-term overall survival data from the SENTRY trial will verify clinical benefit; the potential availability of priority review of the sNDA; expectations with respect to commercialization efforts; expectations regarding the timing of reporting topline data from ongoing clinical trials; the ability of selinexor and eltanexor to treat patients with multiple myeloma, myelofibrosis, and other diseases; expectations with respect to the clinical development plans and potential regulatory submissions of selinexor; and the potential inclusion of the combination of selinexor plus ruxolitinib in relevant compendia. 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; substantial doubt exists regarding Karyopharm's ability to continue as a going concern; development or regulatory approval of drug candidates by Karyopharm's competitors for products or product candidates in which Karyopharm is currently commercializing or developing; 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, 2026, which was filed with the Securities and Exchange Commission (SEC) on May 14, 2026, 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. CONTACTS: Investors: Brendan Strong Senior Vice President, Investor Relations 617.762.2661 [email protected] Media: Mary Ann Ondish Head of Corporate Communications 914.552.4625 [email protected] SOURCE Karyopharm Therapeutics Inc. 21% more press release views with Request a Demo

Site Activation Initiated for Confirmatory Phase 3 Study of Iopofosine I 131 with New Drug Application Submission Planned for mid-2027 under the FDA’s Accelerated Approval Program Presented Data from CLOVER WaM Trial of Iopofosine I 131 in relapsed/refractory Waldenström Macroglobulinemia (r/r WM) at the American Society of Clinical Oncology 2026 Annual Meeting Initiated Enrollment and Dosed First Patients in Phase 1b Clinical Trial of CLR 125 in Triple Negative Breast Cancer Announced Publication of Phase 1 Data in Peer-Reviewed Journal Cancers Company to Hold Webcast and Conference Call at 8:30 AM ET Today FLORHAM PARK, N.J., Aug. 13, 2026 (GLOBE NEWSWIRE) -- Cellectar Biosciences, Inc. (NASDAQ: CLRB), a late-stage clinical biopharmaceutical company focused on the discovery and development of drugs for the treatment of cancer, today announced financial results for the quarter ended June 30, 2026, and provided a corporate update. “Our second quarter marked another period of significant execution as we continued to advance multiple programs across our oncology pipeline while laying the foundation for several important near-term catalysts,” said James Caruso, president and chief executive officer of Cellectar. “Most notably, we progressed our regulatory strategy for iopofosine I 131 in Waldenström macroglobulinemia, including initiation of site activation activities for our confirmatory Phase 3 trial, which is an important first step toward our accelerated approval application in the U.S., which we plan to submit in mid-2027. The compelling data we continue to generate from the Phase 2b CLOVER WaM study reinforce our belief that iopofosine has the potential to address a critical unmet need for WM patients, including those previously treated with BTK inhibitors and prior to off-label salvage therapies.” “At the same time, we continued to expand the clinical validation of our proprietary PDC platform, achieving key enrollment and dosing milestones in our CLR 125 Phase 1b trial in triple-negative breast cancer and advancing our broader radiopharmaceutical portfolio. Supported by a strengthened balance sheet and a clear operational roadmap, we are entering the second half of 2026 with strong momentum, multiple anticipated data and development milestones, and a steadfast commitment to creating long-term value for patients and stockholders.” Second Quarter 2026 and Recent Corporate Highlights Iopofosine I 131, the company’s Phospholipid Drug Conjugate (PDC) designed to provide targeted delivery of iodine-131 (radioisotope) Presented data from the CLOVER WaM study of iopofosine I 131 in relapsed/refractory Waldenström macroglobulinemia (r/r WM) patients at the American Society of Clinical Oncology 2026 Annual Meeting (ASCO). The poster presentation highlighted efficacy results from a subset of patients treated with iopofosine I 131 immediately post-Bruton Tyrosine Kinase inhibitor (BTKi) therapy, which consisted of two cycles administered at 15 mCi/m 2 on days 1 and 15 of each 57-day cycle. Major response rate (MRR) was the primary efficacy endpoint, while the subset analysis also assessed a modified intent-to-treat (mITT) population who were immediately post-BTKi treatment. Efficacy from the evaluable patients (n=24) included: 100% clinical benefit rate 87.5% overall response rate (ORR) 79.2% MRR, partial response (PR) or better Median duration of response (DOR) of 16 months (range: 7.3-25.4 months) 20% of patients exceeded 30 months DOR Treatment was well-tolerated with a manageable toxicity pro cytopenias as the only Grade 3 or greater adverse event. Advanced preparations for the Phase 3 confirmatory trial of iopofosine I 131 and began site initiation activities. Sites are expected to begin opening in the coming months with first patient to be dosed in early 2027. The Phase 3 study will be a comparator, randomized controlled study with approximately 100 WM patients per arm; full patient enrollment is projected within 18-24 months of the first patient admitted to the study. The New Drug Application is planned for submission in mid-2027 under the FDA’s Accelerated Approval Program. Based on the Breakthrough Therapy Designation awarded to iopofosine I 131 for r/r WM, an approximate 6-month review is anticipated. Published results from a Phase 1 dose-escalation study of iopofosine I 131 in combination with low-dose dexamethasone in patients with heavily pretreated relapsed/refractory multiple myeloma (r/r MM) in the peer-reviewed journal, Cancer . Among 26 efficacy-evaluable patients, iopofosine I 131 achieved disease control in 84.6% of patients and an ORR of 15.4%, including four partial responses, with evidence of enhanced clinical activity at higher administered doses and a 30% ORR among evaluable patients receiving at least 60 mCi. Treatment was generally well tolerated, with a favorable safety pro primarily of predictable and reversible hematologic toxicities, no new safety signals, and mostly low-grade non-hematologic adverse events. Given that iopofosine I 131’s mechanism of action is not dependent on a single target or mutation, the company believes these and other data underscore its potential to address a broad range of B-cell-mediated malignancies, including WM, MM, diffuse large B-cell lymphoma and other difficult-to-treat hematologic cancers where new therapeutic options are needed. CLR 121125 (CLR 125), an iodine-125 Auger-emitting program targeted for solid tumor Initiated enrollment and dosing of the first patients in the Phase 1b trial evaluating CLR 125 in refractory triple negative breast cancer (TNBC). Phospholipid Drug Conjugate (PDC) Platform On August 18 th , Cellectar management will host a virtual educational webinar highlighting its validated PDC platform. The webinar will highlight the company’s Phospholipid Drug Conjugates’ (PDCs)™ ability to target and gain intracellular access to most primary tumors, metastatic sites, and cancer stem cells and will underscore how this approach may enhance drug efficacy and simultaneously minimize side effects for patients. The event will showcase how this next-generation proprietary PLE delivery platform was engineered to be conjugated (combined) with a wide variety of therapeutic molecules, such as small-molecule chemotherapeutics, radiotherapeutics, and other molecules that utilize alternative therapeutic approaches. Details of the webinar are below: Date: August 18 th , 2026 Time: 11:30 am – 12:30 pm ET Registration Link: HERE Corporate In May 2026, the company entered into a securities purchase agreement with certain institutional investors and members of executive management to issue and sell an aggregate of approximately $35 million upfront and up to $105 million milestone-based securities in a registered direct offering of common stock and a concurrent private placement of common stock, pre-funded warrants and milestone-based warrants. Proceeds from this financing will primarily be used to fund the Phase 3 confirmatory study of iopofosine I 131 in WM. 2026 Financial Highlights Cash and Cash Equivalents: As of June 30, 2026, the company had cash and cash equivalents of $34.0 million, compared to $13.2 million as of December 31, 2025, which reflects net proceeds of approximately $31.7 million from the May 2026 offering. The company believes its cash balance as of June 30, 2026, is adequate to fund its budgeted operations into the second quarter of 2027. Research and Development Expenses: R&D expenses for the three months ended June 30, 2026, were approximately $4.6 million, compared to approximately $2.4 million for the three months ended June 30, 2025. The initiation of the WM confirmatory iopofosine I 131 and CLR 125 Triple Negative Breast Cancer studies drove the increase. General and Administrative Expenses: G&A expenses for the three months ended June 30, 2026, were approximately $2.6 million, compared to approximately $3.6 million for the same period in 2025. The decrease was primarily a result of reduced commercialization efforts, professional fees, and lower personnel costs. Net Loss: The net loss attributable to common stockholders for the three months ended June 30, 2026, was $6.9 million, or $0.57 per share, compared to $5.4 million, or $3.39 per share, for the three months ended June 30, 2025. Conference Call & Webcast Details Cellectar management will host a conference call and webcast today, August 13, 2026, at 8:30 AM Eastern Time to discuss these results and answer questions. Stockholders and other interested parties may participate in the conference call by dialing 1-800-717-1738. A live webcast of the conference call can be accessed in the “Events & Presentations” section of Cellectar’s website at . A recording of the webcast will be available and archived on the company’s website for approximately 90 days. About Cellectar Biosciences, Inc. Cellectar Biosciences is a late-stage clinical biopharmaceutical company focused on the discovery and development of proprietary drugs for the treatment of cancer, independently and through research and development collaborations. The company’s core objective is to leverage its proprietary Phospholipid Drug Conjugate™ (PDC) delivery platform to develop the next-generation of cancer cell-targeting treatments, delivering improved efficacy and better safety as a result of fewer off-target effects. The company’s product pipeline includes iopofosine I 131, which is a PDC designed to provide targeted delivery of iodine-131 (radioisotope). Iopofosine I 131 has been tested in Phase 2b trials as a treatment for relapsed or refractory Waldenström Macroglobulinemia (WM), in relapsed or refractory multiple myeloma (MM) and central nervous system (CNS) lymphoma. The CLOVER-2 Phase 1b study is evaluating iopofosine I 131 in pediatric patients with high-grade gliomas, for which Cellectar is eligible to receive a Pediatric Review Voucher from the FDA upon approval. The FDA has granted iopofosine I 131 Breakthrough, six Orphan Drug, four Rare Pediatric Drug and two Fast Track Designations for various cancer indications, and the EMA has granted iopofosine I 131 PRIority MEdicines (PRIME) designation. Cellectar is also developing CLR 121125 (CLR 125), an iodine-125 Auger-emitting program targeted for solid tumors, such as triple negative breast (TNBC), lung, and colorectal cancer, and is currently being evaluated in a Phase 1b study for TNBC, which will determine the recommended dose for the subsequent Phase 2 trial. CLR 125 has been well tolerated in vivo and has demonstrated strong preclinical data showing reduction or inhibition of solid tumor growth. In addition to these assets, the Cellectar team is developing CLR 121225 (CLR 225), an actinium-225 based program targeting solid tumors in indications with significant unmet need, such as pancreatic cancer, as well as proprietary preclinical PDC chemotherapeutic programs and multiple partnered PDC assets. For more information, please visit or join the conversation by liking and following us on the company’s social media channels: X , LinkedIn , and Facebook . Forward Looking Statements Disclaimer This news release contains forward-looking statements. You can identify these statements by our use of words such as "may," "expect," "believe," "anticipate," "intend," "could," "estimate," "continue," "plans," or their negatives or cognates. These statements are only estimates and predictions and are subject to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the statements made. These statements are based on our current beliefs and expectations as to such future outcomes. Drug discovery and development involve a high degree of risk. Factors that might cause such a material difference include, among others, uncertainties related to the ability to identify suitable collaborators, partners, licensees or purchasers for our product candidates and, if we are able to do so, to enter into binding agreements with regard to any of the foregoing, or to raise additional capital to support our operations, or our ability to fund our operations if we are unsuccessful with any of the foregoing. A complete description of risks and uncertainties related to our business is contained in our periodic reports filed with the Securities and Exchange Commission including our Form 10-K for the year ended December 31, 2025, and our Form 10-Q for the quarterly period ended March 31, 2026. These forward-looking statements are made only as of the date hereof, and we disclaim any obligation to update any such forward-looking statements. INVESTORS: Anne Marie Fields Precision AQ 212-362-1200 annemarie.fields@precisionaq.com CELLECTAR BIOSCIENCES, INC. CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) June 30, December 31, 2026 2025 ASSETS CURRENT ASSETS: Cash and cash equivalents $ 33,993,982 $ 13,196,033 Prepaid expenses and other current assets 883,659 842,432 Total current assets 34,877,641 14,038,465 Property, plant & equipment, net 304,173 549,405 Operating lease right-of-use asset 1,433,706 360,671 Other long-term assets 23,566 29,780 TOTAL ASSETS $ 36,639,086 $ 14,978,321 LIABILITIES AND STOCKHOLDERS’ EQUITY CURRENT LIABILITIES: Accounts payable and accrued liabilities $ 5,218,681 $ 4,423,548 Warrant liability 17,000 226,000 Lease liability, current 2,030 100,189 Total current liabilities 5,237,711 4,749,737 Lease liability, net of current portion 1,529,542 309,397 TOTAL LIABILITIES 6,767,253 5,059,134 COMMITMENTS AND CONTINGENCIES (Note 7) MEZZANINE EQUITY: Series D preferred stock, 111.11 shares authorized, 0.00 and 111.11 issued and outstanding as of June 30, 2026 and December 31, 2025, respectively — 1,382,023 STOCKHOLDERS’ EQUITY: Series E-2 preferred stock, 1,225 shares authorized; 0.00 and 35.60 shares issued and outstanding as of June 30, 2026 and December 31, 2025, respectively — 520,778 Common stock, $0.00001 par value; 170,000,000 shares authorized; 8,252,108 and 4,240,129 shares issued and outstanding as of June 30, 2026 and December 31, 2025, respectively 83 42 Additional paid-in capital 311,589,849 277,149,844 Accumulated deficit (281,718,099 ) (269,133,500 ) Total stockholders’ equity 29,871,833 8,537,164 TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY $ 36,639,086 $ 14,978,321 CELLECTAR BIOSCIENCES, INC. CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) Three Months Ended June 30, Six Months Ended June 30, 2026 2025 2026 2025 OPERATING EXPENSES: Research and development $ 4,557,383 $ 2,389,801 $ 7,564,612 $ 5,816,896 General and administrative 2,638,629 3,647,728 5,425,341 6,621,624 Total operating expenses 7,196,012 6,037,529 12,989,953 12,438,520 LOSS FROM OPERATIONS (7,196,012 ) (6,037,529 ) (12,989,953 ) (12,438,520 ) OTHER INCOME (EXPENSE): Gain (loss) on valuation of warrants 132,000 501,598 209,000 161,598 Interest income 133,359 88,020 196,355 224,982 Total other income (expense) 265,359 589,618 405,355 386,580 NET LOSS $ (6,930,653 ) $ (5,447,911 ) $ (12,584,598 ) $ (12,051,940 ) NET LOSS PER SHARE — BASIC $ (0.57 ) $ (3.39 ) $ (1.52 ) $ (7.66 ) NET LOSS PER SHARE — DILUTED $ (0.57 ) $ (3.39 ) $ (1.52 ) $ (7.66 ) WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — BASIC 12,231,851 1,608,799 8,258,067 1,572,598 WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — DILUTED 12,231,851 1,608,799 8,258,067 1,572,598