• Seven posters to be presented, including new X-TOLE OLE data supporting the ability to attain and regain extended periods of seizure freedom with long-term use of azetukalner
• Data will also highlight the impact of depression and burden of titration on patients with epilepsy, as well as new pre-clinical data from the Company’s Na_V1.1 program in Dravet syndrome

VANCOUVER, British Columbia and BOSTON, MA, Nov. 25, 2025 (GLOBE NEWSWIRE) -- Xenon Pharmaceuticals Inc. (Nasdaq: XENE), a neuroscience-focused biopharmaceutical company dedicated to drug discovery, clinical development and commercialization of life-changing therapeutics for patients in need, today announced multiple presentations at the upcoming American Epilepsy Society Annual Meeting (AES 2025), taking place December 5-9, 2025 at the Georgia World Congress Center in Atlanta, Georgia. Seven posters will be presented, including new long-term data from the ongoing X-TOLE open-label extension study of azetukalner in patients with focal onset seizures (FOS), and data characterizing patterns of seizure freedom epochs with extended use of azetukalner, which could inform future clinical practice. Xenon’s poster presentations also include findings on the impact of depression on epilepsy patients, as well as new pre-clinical data from the Company’s early-stage Na_V1.1 program in Dravet syndrome.

Long-Term Data for Azetukalner in Epilepsy

• Poster Presentation #1.377: Characterization of Long-Term Seizure Freedom in the Ongoing Open-Label Extension of X-TOLE: Potential Implications for Future Clinical Practice
  Author Session: Saturday, December 6 from 12:00 – 2:00 pm ET in Exhibit Hall B2, Poster Session 1

• Poster Presentation #3.356: Long-Term Safety and Efficacy of Azetukalner, a Novel, Potent K_V7 Potassium Channel Opener, in Adults with Focal Epilepsy: ≥48-Month Interim Analysis of the Ongoing 7-Year X-TOLE Open-Label Extension
  Author Session: Monday, December 8 from 12:00 – 1:45 pm ET in Poster Hall B3, Poster Session 3

Epilepsy Real World Studies

• Poster Presentation #1.364: Depression Symptom Experience Among Patients with Epilepsy Reporting a Diagnosis of Focal Seizures (FS): A Patient-Reported Outcomes Study
  Author Session: Saturday, December 6 from 12:00 – 2:00 pm ET in Exhibit Hall B2, Poster Session 1

• Poster Presentation #1.365: Impact of Depression on Outcomes and Treatment Patterns in Patients with Newly Diagnosed Epilepsy: A Retrospective Claims Analysis
  Author Session: Saturday, December 6 from 12:00 – 2:00 pm ET in Exhibit Hall B2, Poster Session 1

• Poster Presentation #2.325: Multivariable Models Reporting Increased Economic and Humanistic Burden Among Patients With Epilepsy Reporting Focal Seizures (FS) Experiencing Moderate to Severe Depression Symptoms
  Author Session: Sunday, December 7 from 12:00 – 2:00 pm ET in Exhibit Hall B2, Poster Session 2

• Poster Presentation #2.367: Clinical Practice and Patient Burden Associated with Anti-Seizure Medication Titration: A Thematic Analysis
  Author Session: Sunday, December 7 from 12:00 – 2:00 pm ET in Exhibit Hall B2, Poster Session 2

Early-stage Pipeline Data

• Poster Presentation #3.181: Selective Potentiation of Na_V1.1 Channels in Dravet Mice Suppresses Spontaneous Seizures, Prevents SUDEP and Increases Long Term Potentiation
  Author Session: Monday, December 8 from 12:00 – 1:45 pm ET in Poster Hall B3, Poster Session 3

Satellite Symposium

Xenon is hosting a symposium in partnership with the Epilepsy Foundation of America (EFA) entitled “Exploring Depression and Anxiety in Epilepsy: A Practical Dialogue with Patients and Providers” on Saturday, December 6, 2025 from 6:00 – 9:00 pm ET in Room B213. The panel presentation will feature several representatives from EFA, as well as Dr. Jacqueline A. French, epileptologist and neurologist with the NYU Langone Comprehensive Epilepsy Center, Dr. Andres M. Kanner, Professor of Clinical Neurology and Director of the Comprehensive Epilepsy Center and Chief of the Epilepsy Division at the Department of Neurology of the University of Miami, Miller School of Medicine, and Dr. Heidi Marie Munger Clary, Associate Professor of Neurology, Epilepsy Fellowship Director and Director of Faculty Research Development at Wake Forest University School of Medicine.

Scientific Exhibit

Xenon is also hosting a Scientific Exhibit to provide an overview of its clinical- and pre-clinical-stage research programs on Sunday, December 7, 2025 from 2:00 – 5:00 pm ET in Room B304/B305.

For more information about Xenon’s planned participation at AES 2025, please visit this link. Posters will be available after the live presentations.

About Xenon Pharmaceuticals Inc.

Xenon Pharmaceuticals (Nasdaq: XENE) is a neuroscience-focused biopharmaceutical company dedicated to drug discovery, clinical development, and commercialization of life-changing therapeutics for patients in need. Xenon’s lead molecule, azetukalner, is a novel, potent, selective K_V7 potassium channel opener in Phase 3 clinical trials for the treatment of epilepsy, major depressive disorder (MDD) and bipolar depression (BPD). Xenon is also advancing an early-stage portfolio of multiple promising potassium and sodium channel modulators, including K_V7 and Na_V1.7 programs in Phase 1 development for the potential treatment of pain. Xenon has offices in Vancouver, British Columbia, and Boston, Massachusetts. For more information, visit www.xenon-pharma.com and follow us on LinkedIn and X.

Xenon and the Xenon logo are registered trademarks or trademarks of Xenon Pharmaceuticals Inc. in the US, Canada, and elsewhere. All other trademarks belong to their respective owner.

Safe Harbor Statement

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995 and Canadian securities laws. These forward-looking statements are not based on historical fact, and include statements regarding the timing of and potential results from clinical studies; the potential efficacy, safety profile, future development plans in current and anticipated indications, addressable market, regulatory success and commercial potential of our and our partners’ product candidates; the efficacy of our clinical study designs; our ability to successfully develop and achieve milestones in our azetukalner and other pipeline and development programs, including the anticipated filing of INDs and NDAs; the timing and results of our interactions with regulators; our ability to successfully develop and obtain regulatory approval of azetukalner and our other product candidates; and anticipated timing of topline data readout from our clinical studies of azetukalner. These forward-looking statements are based on current assumptions that involve risks, uncertainties and other factors that may cause the actual results, events, or developments to be materially different from those expressed or implied by such forward-looking statements. These risks and uncertainties, many of which are beyond our control, include, but are not limited to: clinical studies may not demonstrate safety and efficacy of any of our or our collaborators’ product candidates; promising results from pre-clinical development activities or early clinical study results may not be replicated in later clinical studies; our assumptions regarding our planned expenditures and sufficiency of our cash to fund operations may be incorrect; our ongoing discovery and pre-clinical efforts may not yield additional product candidates; any of our or our collaborators’ product candidates, including azetukalner, may fail in development, may not receive required regulatory approvals, or may be delayed to a point where they are not commercially viable; we may not achieve additional milestones in our proprietary or partnered programs; regulatory agencies may impose additional requirements or delay the initiation or completion of clinical studies; the impact of market, industry, and regulatory conditions on clinical study enrollment; the impact of competition; the impact of expanded product development and clinical activities on operating expenses; the impact of new or changing laws and regulations; the impact of unstable economic conditions in the general domestic and global economic markets; adverse conditions from geopolitical events; as well as the other risks identified in our filings with the U.S. Securities and Exchange Commission and the securities commissions in British Columbia, Alberta, and Ontario. These forward-looking statements speak only as of the date hereof and we assume no obligation to update these forward-looking statements, and readers are cautioned not to place undue reliance on such forward-looking statements.

Xenon and the Xenon logo are registered trademarks or trademarks of Xenon Pharmaceuticals Inc. in the US, Canada, and elsewhere. All other trademarks belong to their respective owner.

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