XENE Xenon Pharmaceuticals Inc

Xenon Pharmaceuticals Inc. (Nasdaq:XENE), a neuroscience-focused biopharmaceutical company dedicated to discovering, developing, and delivering life-changing therapeutics for patients in need, today announced three poster presentations at the 15th European Epilepsy Congress (EEC) taking place in Rome, Italy. Azetukalner, a novel, potent Kv7 channel opener, is the most advanced, clinically validated potassium channel modulator in late-stage development for multiple indications, including focal onset seizures (FOS), primary generalized tonic-clonic seizures (PGTCS) and major depressive disorder (MDD).

“We are excited for this opportunity to engage with leading epileptologists at EEC in Rome and share long-term azetukalner data from our ongoing X-TOLE open-label extension study. Azetukalner represents the only Kv7 potassium channel opener in clinical development that is supported by Phase 2b data as well as long-term efficacy and safety data in epilepsy patients,” stated Dr. Christopher Kenney, Chief Medical Officer of Xenon. “These data are particularly impressive given the baseline disease severity, with patients who are out to 30 months in the open-label extension study showing a greater than 90% reduction in median monthly seizure frequency, while approximately one in four patients on azetukalner for at least two years in the OLE have experienced a period of seizure freedom of a year or longer.”

Dr. Kenney continued, “We are also presenting patient-reported survey data illustrating the substantial burden of illness for people living with epilepsy, with reduced quality of life, high seizure frequency and fatigue, as well as other comorbidities such as anxiety and depression, further underscoring the need for new medications to help people living with epilepsy.”

Presentations at EEC:

Poster #P282: Azetukalner (XEN1101), a Novel, Potent Kv7 Potassium Channel Opener: Interim Data From an Ongoing, Long‑Term, Open‑Label Extension of a Phase 2b Study (X‑TOLE) in Adults With Focal Onset SeizuresPresenter: Jacqueline A. French, New York University Grossman School of Medicine and NYU Langone Health, New York, NYSession Times: Daily from 1:30-3:00 pm CEST

Poster #P281: Long-term, Quality of Life in Epilepsy Inventory-31 (QOLIE-31) Improvements in Adults With Focal Onset Seizures Treated With Azetukalner (XEN1101) in an Ongoing, Open-Label Extension of a Phase 2b study (X-TOLE)Presenter: Christian Brandt, Bethel Epilepsy Centre, Mara Hospital, University Hospital for Epileptology, Bielefeld, GermanySession Times: Daily from 1:30-3:00 pm CESTPoster Tour: S2 Clinical Neurophysiology/Drug Therapy

Poster #P406: Non-seizure Symptoms, Mental Health Comorbidities, and Quality of Life in Patients Reporting Focal Onset SeizuresPresenter: Cynthia Harden, Xenon Pharmaceuticals Inc. Session Times: Daily from 1:30-3:00 pm CEST

Posters will be available for viewing at the conference from Sunday, September 8 until Tuesday, September 10 at 4:00 pm CEST and will be added to the Xenon website consistent with conference guidelines. Xenon is also hosting a Scientific Exhibit at location SE1 and Booth #346.

About Xenon Pharmaceuticals Inc.Xenon Pharmaceuticals (Nasdaq:XENE) is a neuroscience-focused biopharmaceutical company committed to discovering, developing, and commercializing innovative therapeutics to improve the lives of people living with neurological and psychiatric disorders. We are advancing a novel product pipeline to address areas of high unmet medical need, including epilepsy and depression. Azetukalner, our lead Kv7 channel opener, represents the most advanced, clinically validated potassium channel modulator in late-stage clinical development for multiple indications. For more information, please visit www.xenon-pharma.com.

About the Azetukalner Phase 3 Epilepsy ProgramXenon’s Phase 3 epilepsy program includes three ongoing Phase 3 clinical trials in focal onset seizures (FOS) and primary generalized tonic-clonic seizures (PGTCS). Designed closely after the Phase 2b X-TOLE clinical trial, the Phase 3 X-TOLE clinical trials are multicenter, randomized, double-blind, placebo-controlled studies evaluating the clinical efficacy, safety, and tolerability of 15 mg or 25 mg of azetukalner administered with food as adjunctive treatment in approximately 360 patients with FOS per study. The primary efficacy endpoint is the median percent change (MPC) in monthly seizure frequency from baseline through the double-blind period (DBP) of azetukalner compared to placebo. X-ACKT is a multicenter, randomized, double-blind, placebo-controlled study evaluating the clinical efficacy, safety, and tolerability of 25 mg of azetukalner administered with food as adjunctive treatment in approximately 160 patients with PGTCS. The primary efficacy endpoint is the MPC in monthly PGTCS frequency from baseline through the DBP of azetukalner compared to placebo.

Safe Harbor StatementThis 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 trials; 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 trial designs; our ability to successfully develop and achieve milestones in our azetukalner and other pipeline and development programs; and our ability to successfully develop and obtain regulatory approval of azetukalner and our other product candidates. 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 trials 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 trial results may not be replicated in later clinical trials; 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 of clinical trials; the impact of market, industry, and regulatory conditions on clinical trial 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; 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 various jurisdictions. All other trademarks belong to their respective owner.

Contacts: For Investors:Chad FugereVice President, Investor Relations(857) 675-7275investors@xenon-pharma.com

For Media:Colleen AlabisoSenior Vice President, Corporate Affairs(617) 671-9238media@xenon-pharma.com