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New seizure drug shows promise in late-stage trial

NCT ID NCT05667142

Disease control Sponsor: Xenon Pharmaceuticals Inc. Source: ClinicalTrials.gov ↗

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now This study
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Jun 27, 2026 · Last updated Aug 11, 2026 · Updated 4 times

Summary

This study tests whether XEN1101, taken alongside current seizure medications, can reduce the number of generalized tonic-clonic seizures (convulsions affecting the whole body). About 160 people aged 12 and older with these seizures will receive either XEN1101 or a placebo for several months. The goal is to see if the drug safely lowers seizure frequency and helps some people become seizure-free.

Why investors are watching

Xenon Pharmaceuticals is running a Phase 3 trial of its drug XEN1101 for primary generalized tonic-clonic seizures, a type of epilepsy. For a small company, this late-stage readout is a major event because a positive result could support regulatory approval and define the drug's commercial future.

If it works: If the trial shows XEN1101 safely reduces seizures better than placebo, Xenon could move closer to bringing its first drug to market. That outcome would validate years of research and give the company a product with clear patient demand.

If it fails: Phase 3 trials often fail, and a negative or unclear result would likely set the program back and hurt the company's prospects. A delay in the readout could also strain a small firm's resources and investor confidence.

AI-written from the trial record. Speculative, and not investment advice.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 3

Large-scale testing in a bigger group. Usually the last step before a treatment can be approved.

Participants

About 160 people

The number the study aims to enrol. It can still change while the study runs.

Started

Feb 2023

Expected to finish

Jun 2027

An estimate. End dates often move.

Lead sponsor

A company

The lead sponsor is a pharmaceutical, biotech, or medical-device company.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

12 years and older

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Key Inclusion Criteria: 1. Subject is properly informed of the nature and risks of the study and gives informed consent in writing prior to entering the study (for adult subjects) and for adolescent subjects parent/legal guardian and subject gives informed consent or assent in writing prior to entering the study. 2. Subject is ≥12 years of age with a BMI ≤40 kg/m2 at Visit 1. 3. Subject must have had adequate trials of at least 2 ASMs, which were given (and tolerated) at adequate therapeutic doses, without achieving sustained seizure freedom. 4. Subject has probable or possible PGTCS (with or without other subtypes of generalized seizures) for ≥1 year, in the setting of generalized epilepsy according to the International League Against Epilepsy 2017 classification criteria, and subject is approved by The Epilepsy Study Consortium (TESC). 5. Subject is on a stable dose of 1 to 3 allowable current ASMs for at least 3 months prior to the planned randomization (Visit 2), during screening/baseline, and throughout the DBP. 6. Subject is able to keep accurate seizure diaries. Key Exclusion Criteria: 1. Subject has had status epilepticus within the 12 months prior to Visit 1. 2. Subject has history of repetitive seizures within the 12-month period preceding Visit 1 where the individual seizures cannot be counted. 3. Subject has a history of non-epileptic psychogenic seizures within 10 years prior to Visit 1. 4. Subject has a concomitant diagnosis of focal-onset seizures (FOS). 5. Subject has presence or history of a developmental and epileptic encephalopathy, including Lennox-Gastaut syndrome. 6. Subject has seizures secondary to drug or alcohol use, ongoing infection, neoplasia, demyelinating disease, degenerative neurological disease, metabolic illness, progressive structural lesion, encephalopathy, or progressive central nervous system (CNS) disease. 7. Subject has history of neurosurgery for seizures \<1 year prior to Visit 1, or radiosurgery \<2 years prior to Visit 1. 8. Subject has schizophrenia and other psychotic disorders (eg, schizophreniform disorder, schizoaffective disorder, psychosis not otherwise specified), bipolar disorder, or another serious mental health disorder. Subject has uncontrolled unipolar major depression where changes in pharmacotherapy are needed or anticipated during the study. 9. Subject has any clinically significant laboratory abnormalities or clinically significant abnormalities on prestudy physical examination, vital signs, or ECG that, in the judgment of the investigator, indicate a medical problem that would preclude study participation, including but not limited to: a. History or presence of long QT syndrome; QTcF \>450 msec at baseline; family history of sudden death of unknown cause. 10. Any personal circumstance that, in the opinion of the investigator, prevents adherence to the protocol. The criteria to be eligible for randomization are: 1. During the last 56 days that preceded the randomization visit (Visit 2), subject must have had a sufficient documented seizure frequency of PGTCS, including ≥1 PGTCS during each of the first and second 4-week periods preceding randomization. Retrospective seizure data documented up to 4 weeks prior to Visit 1 may be used in combination with a minimum of 4 weeks of prospective seizure data recorded in the study eDiary. 2. Study eDiary was completed a minimum of 80% of all applicable days during the last 28-56 days of the baseline period that preceded randomization as evidence of adequate compliance (eg, \>45 of 56 days, if no retrospective data prior to Visit 1 are used). 3. Subject did not change dose of, stop, or initiate any new ASM(s) during the 3 months that preceded randomization and plans on maintaining a stable dose of ASM(s) during the DBP.

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Conditions

The condition(s) this trial relates to.

epilepsy epilepsy with generalized tonic-clonic seizures

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Primary generalized tonic-clonic seizures

How to take part

Only the study team decides who joins. These are the ways to reach them.

  1. The places running it

    102 sites in 15 countries. The list below names each one and where it is.

  2. The official record

    ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.

    Open the record ↗

  3. A doctor treating you

    A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.

Contacts and locations

Locations

  • ANESC Research

    RECRUITING

    El Paso, Texas, 79912, United States

  • Advocate Aurora Research institute, St. Luke's Medical Center

    RECRUITING

    Milwaukee, Wisconsin, 53215, United States

  • Atrium Health

    RECRUITING

    Charlotte, North Carolina, 28203, United States

  • Austin Health Pharmacy Clinical Trials

    RECRUITING

    Heidelberg, Victoria, 3084, Australia

  • Azienda Ospedaliero Universitaria Ospedali Riuniti Ancona

    WITHDRAWN

    Ancona, 60126, Italy

  • Azienda Ospedaliero Universitaria Pisana

    RECRUITING

    Pisa, 56126, Italy

  • Bethel Epilepsy Centre

    RECRUITING

    Bielefeld, 33617, Germany

  • Bluegrass Epilepsy Research, LLC

    RECRUITING

    Lexington, Kentucky, 40504, United States

  • Brain Science Research Institute

    RECRUITING

    Los Angeles, California, 90025, United States

  • Brigham and Women's Hospital

    RECRUITING

    Chestnut Hill, Massachusetts, 02467, United States

  • CHU de Lille, Hôpital Roger Salengro - Neurophysiologie clinique

    RECRUITING

    Lille, 59037, France

  • CHU de Rennes - Hôpital Pontchaillou

    RECRUITING

    Rennes, 35033, France

  • CHU de Strasbourg - Hôpital de Hautepierre

    RECRUITING

    Strasbourg, 67098, France

  • COPERNICUS Podmiot Leczniczy Sp. z o.o.

    RECRUITING

    Gdansk, 80-803, Poland

  • Center for Neurologic Research

    RECRUITING

    Lethbridge, Alberta, T1J 0N9, Canada

  • Centre Hospitalar Universitario de Lisboa Norte (CHULN)

    RECRUITING

    Lisbon, 1649-035, Portugal

  • Centro Hospitalar Lisboa Ocidental, Hospital Egas Moniz

    RECRUITING

    Lisbon, 1349-019, Portugal

  • Centro Hospitalar Universitário de Coimbra (CHUC)

    RECRUITING

    Coimbra, 3000-075, Portugal

  • Centro Hospitalar Universitário de Santo António

    WITHDRAWN

    Porto, 4050-342, Portugal

  • Centro Hospitalar de Entre o Douro e Vouga

    WITHDRAWN

    Santa Maria da Feira, 4520-211, Portugal

  • Centro de investigación Clinica UC-CICUC

    ACTIVE_NOT_RECRUITING

    Santiago, Chile

  • Centrum Medyczne Neuromed

    RECRUITING

    Bydgoszcz, 85-163, Poland

  • Children and Women's Health Centre of BC (BC Children's Hospital)

    RECRUITING

    Vancouver, British Columbia, V6H 3V4, Canada

  • Children's Healthcare of Atlanta

    RECRUITING

    Atlanta, Georgia, 30342, United States

  • Cleveland Clinic Foundation

    RECRUITING

    Cleveland, Ohio, 44195, United States

  • Clinical Hospital Center Osijek

    WITHDRAWN

    Osijek, 310 00, Croatia

  • Clinical Hospital Center Rijeka

    WITHDRAWN

    Rijeka, 510 00, Croatia

  • Cliniques Universitaires Saint-Luc

    RECRUITING

    Brussels, 1200, Belgium

  • Consultants in Epilepsy and Neurology, PLLC

    RECRUITING

    Boise, Idaho, 83702, United States

  • Dent Neurosciences Research Facility

    TERMINATED

    Amherst, New York, 14226, United States

  • Duke University Clinical Research

    RECRUITING

    Durham, North Carolina, 27710, United States

  • Emory Brain Health Center

    RECRUITING

    Atlanta, Georgia, 30329, United States

  • Encore Medical Research of Weston, LLC

    RECRUITING

    Weston, Florida, 33331, United States

  • Epilepsiezentrum Kleinwachau gemeinnützige GmbH

    WITHDRAWN

    Radeberg, 01454, Germany

  • Epilepsiezentrum im Neuozentrum

    RECRUITING

    Freiburg im Breisgau, 79106, Germany

  • Fakultni nemocnice v Motole Neurologicka klinika 2. LF UK a FN Motol

    WITHDRAWN

    Prague, 150 06, Czechia

  • First University Multiprofile Hospital for Active Treatment Sofia Sv. Joan Krastitel

    WITHDRAWN

    Sofia, 1142, Bulgaria

  • Five Towns Neurology

    WITHDRAWN

    Woodmere, New York, 11598, United States

  • Georgia Neurology & Sleep Medicine Associates

    WITHDRAWN

    Suwanee, Georgia, 30024, United States

  • Grupo Medico Camino SC

    ACTIVE_NOT_RECRUITING

    Mexico City, 03310, Mexico

  • Hadassah University Medical Center

    RECRUITING

    Jerusalem, 9112001, Israel

  • Hawaii Pacific Neuroscience, Comprehensive Epilepsy Center

    WITHDRAWN

    Honolulu, Hawaii, 96817, United States

  • Hopital Neurologique Pierre Wertheimer, Hospices Civils de Lyon

    RECRUITING

    Lyon, 9003, France

  • Hospital Clinico Universitario de Valladolid

    WITHDRAWN

    Valladolid, 47003, Spain

  • Hospital Clinico Viña del Mar

    ACTIVE_NOT_RECRUITING

    Valparaíso, 2520612, Spain

  • Hospital General de Agudos J.M. Ramos Mejia

    WITHDRAWN

    Buenos Aires, 1221, Argentina

  • Hospital Italiano

    WITHDRAWN

    Buenos Aires, C1181ACH, Argentina

  • Hospital Regional Universitario de Málaga

    WITHDRAWN

    Málaga, 29010, Spain

  • Hospital Universitario 12 de Octubre

    WITHDRAWN

    Madrid, 280 41, Spain

  • Hospital Universitario Vithas Madrid La Milagrosa

    WITHDRAWN

    Madrid, 28010, Spain

  • Hospital da Senhora da Oliveira

    RECRUITING

    Guimarães, 4835-044, Portugal

  • Human Science Research Trials S. de R.L. de C.V.

    ACTIVE_NOT_RECRUITING

    Mexico City, 14050, Mexico

  • Hôpital Fondation A. de Rothschild

    RECRUITING

    Paris, 75019, France

  • Indiana University School of Medicine

    WITHDRAWN

    Indianapolis, Indiana, 46202, United States

  • John Radcliffe Hospital

    RECRUITING

    Oxford, OX3 9DU, United Kingdom

  • Kaplan Medical Center

    RECRUITING

    Rehovot, 7661041, Israel

  • Kempenhaeghe

    RECRUITING

    Heeze, 5591BL VE, Netherlands

  • Klinikum der Universität München

    RECRUITING

    München, 81377, Germany

  • Le Centre Hospitalier de l'Universite' de Montreal (CHUM)

    RECRUITING

    Montreal, Quebec, H2X 0C1, Canada

  • London Health Sciences Center

    RECRUITING

    London, Ontario, N6A5A5, Canada

  • MHATNP 'Sveti Naum' EAD

    RECRUITING

    Sofia, 1113, Bulgaria

  • Mater Misericordiae Ltd

    RECRUITING

    South Brisbane, Queensland, 4101, Australia

  • Mayo Clinic Florida

    RECRUITING

    Jacksonville, Florida, 32224, United States

  • MedStar Franklin Square Medical Center

    RECRUITING

    Baltimore, Maryland, 21237, United States

  • Medical University of South Carolina (MUSC)

    WITHDRAWN

    Charleston, South Carolina, 29425, United States

  • Medsol Clinical Research Center Harbor Professional Centre

    RECRUITING

    Port Charlotte, Florida, 33952, United States

  • Medstar Georgetown University Hospital

    RECRUITING

    Clinton, Maryland, 20735, United States

  • Michigan State University Department of Neurology

    RECRUITING

    East Lansing, Michigan, 48824, United States

  • Mid Yorkshire Hospitals NHS Trust

    RECRUITING

    Wakefield, West Yorkshire, WF1 4DG, United Kingdom

  • Mid-Atlantic Epilepsy and Sleep Center

    RECRUITING

    Bethesda, Maryland, 20817, United States

  • Multiprofile hospital for active treatment Puls AD

    RECRUITING

    Blagoevgrad, 2700, Bulgaria

  • NZOZ Neuromed M. i M.

    WITHDRAWN

    Lublin, 20-064, Poland

  • Neurociencias Estudios Clínicos S.C

    ACTIVE_NOT_RECRUITING

    Sinaloa, 80020, Mexico

  • Northeast Regional Epilepsy Group

    RECRUITING

    Hackensack, New Jersey, 07601, United States

  • Novo-Med Zielinski I Wspolnicy Sp. J.

    RECRUITING

    Katowice, 40-584, Poland

  • OhioHealth Riverside Methodist Hospital

    RECRUITING

    Columbus, Ohio, 43214, United States

  • Onsite Clinical Solutions, LLC

    RECRUITING

    Charlotte, North Carolina, 28211, United States

  • Ospedalo Pediatrico Bambino Gesu

    RECRUITING

    Roma, 00165, Italy

  • Panhandle Research and Medical Clinic

    RECRUITING

    Pensacola, Florida, 32503, United States

  • Philipps-Universität Marburg

    RECRUITING

    Marburg, 35043, Germany

  • Policlinico Umberto I

    RECRUITING

    Roma, 185, Italy

  • Research Institute of Orlando, LLC

    TERMINATED

    Orlando, Florida, 32806, United States

  • STAT Research S.A.

    RECRUITING

    Buenos Aires, C1023AAB, Argentina

  • SUNY Upstate Medical University

    RECRUITING

    Syracuse, New York, 13201, United States

  • Saint Louis University Medical School

    RECRUITING

    St Louis, Missouri, 14624, United States

  • Salford Royal NHS Foundation Trust - Greater Manchester Neuroscience Centre (GMNC)

    RECRUITING

    Salford, M6 8HD, United Kingdom

  • Sanatorio del Sur S.A

    ACTIVE_NOT_RECRUITING

    San Miguel de Tucumán, 4000, Argentina

  • Sentara Neurology Specialists

    RECRUITING

    Virginia Beach, Virginia, 23456, United States

  • Serenity Research Center, LLC

    RECRUITING

    Miami, Florida, 33176, United States

  • Southern Illinois University School of Medicine

    RECRUITING

    Springfield, Illinois, 62794, United States

  • Southern Neurology

    WITHDRAWN

    Kogarah, New South Wales, 2217, Australia

  • Spectrum Health

    RECRUITING

    Grand Rapids, Michigan, 49503, United States

  • St George's University Hospitals NHS Foundation Trust

    RECRUITING

    London, SW17 0QT, United Kingdom

  • St Vincent's Hospital Melbourne, Clinical Neurosciences

    WITHDRAWN

    Melbourne, Victoria, 3065, Australia

  • Summa Health Clinical Research Center

    RECRUITING

    Akron, Ohio, 44304, United States

  • Temple University Hospital

    RECRUITING

    Philadelphia, Pennsylvania, 19140, United States

  • The Alfred Hospital

    RECRUITING

    Melbourne, VC, 3004, Australia

  • The Chaim Sheba Medical Center

    RECRUITING

    Ramat Gan, 6265601, Israel

  • The Ohio State University

    RECRUITING

    Columbus, Ohio, 43210, United States

  • The Royal Melbourne Hospital

    RECRUITING

    Parkville, 3050, Australia

  • The Tel Aviv Sourasky Medical Center

    RECRUITING

    Tel Aviv, 64239, Israel

  • Twoja Przychodnia Nowosolskie Centrum Medyczne

    RECRUITING

    Nowa Sól, 67-100, Poland

  • UMass Memorial Medical Center

    WITHDRAWN

    Worcester, Massachusetts, 01655, United States

  • UPMC Comprehensive Epilepsy Center

    RECRUITING

    Pittsburgh, Pennsylvania, 15213, United States

  • UTHealth Science Center at Houston

    RECRUITING

    Houston, Texas, 77030, United States

  • Unidade Local de Saúde de Matosinhos

    RECRUITING

    Matosinhos Municipality, 4450-024, Portugal

  • Universitaetsklinik fuer Kinder

    RECRUITING

    Linz, 4021, Austria

  • Universitair Ziekenhuis Gent

    RECRUITING

    Ghent, 9000, Belgium

  • University California, Davis Clinical & Translation Science Center Clinical Research (CCRC)

    WITHDRAWN

    Sacramento, California, 95817, United States

  • University College London Hospitals NHS Foundation Trust

    RECRUITING

    London, WC1N 3BG, United Kingdom

  • University Hospital Center Zagreb

    WITHDRAWN

    Zagreb, 100 00, Croatia

  • University Hospital Innsbruck

    RECRUITING

    Innsbruck, 6020, Austria

  • University Hospital of Wales

    RECRUITING

    Cardiff, Wales, CF14 4XW, United Kingdom

  • University of Alabama - Strada Patient Care Center, Neurology

    RECRUITING

    Mobile, Alabama, 36604, United States

  • University of Arizona - Health Science Center

    RECRUITING

    Tucson, Arizona, 85724, United States

  • University of Arkansas for Medical Sciences

    RECRUITING

    Little Rock, Arkansas, 72205, United States

  • University of California, Irvine - Health Neurology Services

    RECRUITING

    Orange, California, 92868, United States

  • University of Colorado Anschutz Medical Campus

    WITHDRAWN

    Aurora, Colorado, 80045, United States

  • University of Kansas Medical Center

    RECRUITING

    Kansas City, Kansas, 66160, United States

  • University of Kentucky Albert B. Chandler Hospital (UK Healthcare)

    RECRUITING

    Lexington, Kentucky, 40536, United States

  • University of Maryland Medical Center

    RECRUITING

    Baltimore, Maryland, 21201, United States

  • University of Michigan Hospitals

    RECRUITING

    Ann Arbor, Michigan, 48109, United States

  • University of Pennsylvania

    RECRUITING

    Philadelphia, Pennsylvania, 19104, United States

  • University of South Florida

    RECRUITING

    Tampa, Florida, 33606, United States

  • University of Texas Health Science Center at San Antonio

    RECRUITING

    San Antonio, Texas, 78229, United States

  • University of Utah Clinical Neurosciences Center

    ACTIVE_NOT_RECRUITING

    Salt Lake City, Utah, 84132, United States

  • University of Washington, Regional Epilepsy Center at Harborview Medical Center

    RECRUITING

    Seattle, Washington, 98104, United States

  • Università Degli Studi Gabriele d'Annunzio Di Chieti

    RECRUITING

    Chieti, 66100, Italy

  • Universitätsklinik für Neurologie

    RECRUITING

    Salzburg, 5020, Austria

  • Universitätsklinik für Neurologie, Medizinische Universität Wien

    RECRUITING

    Vienna, 1090, Austria

  • Universitätsklinikum Aachen

    RECRUITING

    Aachen, D-52074, Germany

  • Universitätsklinikum Frankfurt

    RECRUITING

    Frankfurt, 60528, Germany

  • Universitätsklinikum Tübingen

    RECRUITING

    Tübingen, 72076, Germany

  • Universitätsklinikum Ulm

    RECRUITING

    Ulm, 89081, Germany

  • Vivantes Humboldt Klinikum

    WITHDRAWN

    Berlin, 13509, Germany

  • Wake Forest Baptist Health

    RECRUITING

    Winston-Salem, North Carolina, 27104, United States

  • Wayne State University

    RECRUITING

    Detroit, Michigan, 48201, United States

  • Xenoscience

    RECRUITING

    Phoenix, Arizona, 85004, United States

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