New seizure drug shows promise in late-stage trial
NCT ID NCT05667142
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
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Phase 3
Large-scale testing in a bigger group. Usually the last step before a treatment can be approved.
- Participants
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About 160 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Feb 2023
- Expected to finish
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Jun 2027
An estimate. End dates often move.
- Lead sponsor
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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
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12 years and older
- Sex
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Anyone
- Healthy volunteers
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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 Hide 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.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
102 sites in 15 countries. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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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
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ANESC Research
RECRUITINGEl Paso, Texas, 79912, United States
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Advocate Aurora Research institute, St. Luke's Medical Center
RECRUITINGMilwaukee, Wisconsin, 53215, United States
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Atrium Health
RECRUITINGCharlotte, North Carolina, 28203, United States
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Austin Health Pharmacy Clinical Trials
RECRUITINGHeidelberg, Victoria, 3084, Australia
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Azienda Ospedaliero Universitaria Ospedali Riuniti Ancona
WITHDRAWNAncona, 60126, Italy
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Azienda Ospedaliero Universitaria Pisana
RECRUITINGPisa, 56126, Italy
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Bethel Epilepsy Centre
RECRUITINGBielefeld, 33617, Germany
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Bluegrass Epilepsy Research, LLC
RECRUITINGLexington, Kentucky, 40504, United States
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Brain Science Research Institute
RECRUITINGLos Angeles, California, 90025, United States
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Brigham and Women's Hospital
RECRUITINGChestnut Hill, Massachusetts, 02467, United States
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CHU de Lille, Hôpital Roger Salengro - Neurophysiologie clinique
RECRUITINGLille, 59037, France
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CHU de Rennes - Hôpital Pontchaillou
RECRUITINGRennes, 35033, France
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CHU de Strasbourg - Hôpital de Hautepierre
RECRUITINGStrasbourg, 67098, France
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COPERNICUS Podmiot Leczniczy Sp. z o.o.
RECRUITINGGdansk, 80-803, Poland
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Center for Neurologic Research
RECRUITINGLethbridge, Alberta, T1J 0N9, Canada
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Centre Hospitalar Universitario de Lisboa Norte (CHULN)
RECRUITINGLisbon, 1649-035, Portugal
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Centro Hospitalar Lisboa Ocidental, Hospital Egas Moniz
RECRUITINGLisbon, 1349-019, Portugal
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Centro Hospitalar Universitário de Coimbra (CHUC)
RECRUITINGCoimbra, 3000-075, Portugal
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Centro Hospitalar Universitário de Santo António
WITHDRAWNPorto, 4050-342, Portugal
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Centro Hospitalar de Entre o Douro e Vouga
WITHDRAWNSanta Maria da Feira, 4520-211, Portugal
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Centro de investigación Clinica UC-CICUC
ACTIVE_NOT_RECRUITINGSantiago, Chile
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Centrum Medyczne Neuromed
RECRUITINGBydgoszcz, 85-163, Poland
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Children and Women's Health Centre of BC (BC Children's Hospital)
RECRUITINGVancouver, British Columbia, V6H 3V4, Canada
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Children's Healthcare of Atlanta
RECRUITINGAtlanta, Georgia, 30342, United States
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Cleveland Clinic Foundation
RECRUITINGCleveland, Ohio, 44195, United States
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Clinical Hospital Center Osijek
WITHDRAWNOsijek, 310 00, Croatia
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Clinical Hospital Center Rijeka
WITHDRAWNRijeka, 510 00, Croatia
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Cliniques Universitaires Saint-Luc
RECRUITINGBrussels, 1200, Belgium
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Consultants in Epilepsy and Neurology, PLLC
RECRUITINGBoise, Idaho, 83702, United States
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Dent Neurosciences Research Facility
TERMINATEDAmherst, New York, 14226, United States
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Duke University Clinical Research
RECRUITINGDurham, North Carolina, 27710, United States
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Emory Brain Health Center
RECRUITINGAtlanta, Georgia, 30329, United States
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Encore Medical Research of Weston, LLC
RECRUITINGWeston, Florida, 33331, United States
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Epilepsiezentrum Kleinwachau gemeinnützige GmbH
WITHDRAWNRadeberg, 01454, Germany
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Epilepsiezentrum im Neuozentrum
RECRUITINGFreiburg im Breisgau, 79106, Germany
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Fakultni nemocnice v Motole Neurologicka klinika 2. LF UK a FN Motol
WITHDRAWNPrague, 150 06, Czechia
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First University Multiprofile Hospital for Active Treatment Sofia Sv. Joan Krastitel
WITHDRAWNSofia, 1142, Bulgaria
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Five Towns Neurology
WITHDRAWNWoodmere, New York, 11598, United States
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Georgia Neurology & Sleep Medicine Associates
WITHDRAWNSuwanee, Georgia, 30024, United States
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Grupo Medico Camino SC
ACTIVE_NOT_RECRUITINGMexico City, 03310, Mexico
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Hadassah University Medical Center
RECRUITINGJerusalem, 9112001, Israel
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Hawaii Pacific Neuroscience, Comprehensive Epilepsy Center
WITHDRAWNHonolulu, Hawaii, 96817, United States
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Hopital Neurologique Pierre Wertheimer, Hospices Civils de Lyon
RECRUITINGLyon, 9003, France
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Hospital Clinico Universitario de Valladolid
WITHDRAWNValladolid, 47003, Spain
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Hospital Clinico Viña del Mar
ACTIVE_NOT_RECRUITINGValparaíso, 2520612, Spain
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Hospital General de Agudos J.M. Ramos Mejia
WITHDRAWNBuenos Aires, 1221, Argentina
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Hospital Italiano
WITHDRAWNBuenos Aires, C1181ACH, Argentina
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Hospital Regional Universitario de Málaga
WITHDRAWNMálaga, 29010, Spain
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Hospital Universitario 12 de Octubre
WITHDRAWNMadrid, 280 41, Spain
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Hospital Universitario Vithas Madrid La Milagrosa
WITHDRAWNMadrid, 28010, Spain
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Hospital da Senhora da Oliveira
RECRUITINGGuimarães, 4835-044, Portugal
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Human Science Research Trials S. de R.L. de C.V.
ACTIVE_NOT_RECRUITINGMexico City, 14050, Mexico
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Hôpital Fondation A. de Rothschild
RECRUITINGParis, 75019, France
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Indiana University School of Medicine
WITHDRAWNIndianapolis, Indiana, 46202, United States
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John Radcliffe Hospital
RECRUITINGOxford, OX3 9DU, United Kingdom
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Kaplan Medical Center
RECRUITINGRehovot, 7661041, Israel
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Kempenhaeghe
RECRUITINGHeeze, 5591BL VE, Netherlands
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Klinikum der Universität München
RECRUITINGMünchen, 81377, Germany
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Le Centre Hospitalier de l'Universite' de Montreal (CHUM)
RECRUITINGMontreal, Quebec, H2X 0C1, Canada
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London Health Sciences Center
RECRUITINGLondon, Ontario, N6A5A5, Canada
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MHATNP 'Sveti Naum' EAD
RECRUITINGSofia, 1113, Bulgaria
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Mater Misericordiae Ltd
RECRUITINGSouth Brisbane, Queensland, 4101, Australia
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Mayo Clinic Florida
RECRUITINGJacksonville, Florida, 32224, United States
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MedStar Franklin Square Medical Center
RECRUITINGBaltimore, Maryland, 21237, United States
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Medical University of South Carolina (MUSC)
WITHDRAWNCharleston, South Carolina, 29425, United States
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Medsol Clinical Research Center Harbor Professional Centre
RECRUITINGPort Charlotte, Florida, 33952, United States
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Medstar Georgetown University Hospital
RECRUITINGClinton, Maryland, 20735, United States
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Michigan State University Department of Neurology
RECRUITINGEast Lansing, Michigan, 48824, United States
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Mid Yorkshire Hospitals NHS Trust
RECRUITINGWakefield, West Yorkshire, WF1 4DG, United Kingdom
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Mid-Atlantic Epilepsy and Sleep Center
RECRUITINGBethesda, Maryland, 20817, United States
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Multiprofile hospital for active treatment Puls AD
RECRUITINGBlagoevgrad, 2700, Bulgaria
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NZOZ Neuromed M. i M.
WITHDRAWNLublin, 20-064, Poland
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Neurociencias Estudios Clínicos S.C
ACTIVE_NOT_RECRUITINGSinaloa, 80020, Mexico
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Northeast Regional Epilepsy Group
RECRUITINGHackensack, New Jersey, 07601, United States
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Novo-Med Zielinski I Wspolnicy Sp. J.
RECRUITINGKatowice, 40-584, Poland
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OhioHealth Riverside Methodist Hospital
RECRUITINGColumbus, Ohio, 43214, United States
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Onsite Clinical Solutions, LLC
RECRUITINGCharlotte, North Carolina, 28211, United States
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Ospedalo Pediatrico Bambino Gesu
RECRUITINGRoma, 00165, Italy
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Panhandle Research and Medical Clinic
RECRUITINGPensacola, Florida, 32503, United States
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Philipps-Universität Marburg
RECRUITINGMarburg, 35043, Germany
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Policlinico Umberto I
RECRUITINGRoma, 185, Italy
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Research Institute of Orlando, LLC
TERMINATEDOrlando, Florida, 32806, United States
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STAT Research S.A.
RECRUITINGBuenos Aires, C1023AAB, Argentina
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SUNY Upstate Medical University
RECRUITINGSyracuse, New York, 13201, United States
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Saint Louis University Medical School
RECRUITINGSt Louis, Missouri, 14624, United States
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Salford Royal NHS Foundation Trust - Greater Manchester Neuroscience Centre (GMNC)
RECRUITINGSalford, M6 8HD, United Kingdom
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Sanatorio del Sur S.A
ACTIVE_NOT_RECRUITINGSan Miguel de Tucumán, 4000, Argentina
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Sentara Neurology Specialists
RECRUITINGVirginia Beach, Virginia, 23456, United States
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Serenity Research Center, LLC
RECRUITINGMiami, Florida, 33176, United States
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Southern Illinois University School of Medicine
RECRUITINGSpringfield, Illinois, 62794, United States
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Southern Neurology
WITHDRAWNKogarah, New South Wales, 2217, Australia
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Spectrum Health
RECRUITINGGrand Rapids, Michigan, 49503, United States
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St George's University Hospitals NHS Foundation Trust
RECRUITINGLondon, SW17 0QT, United Kingdom
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St Vincent's Hospital Melbourne, Clinical Neurosciences
WITHDRAWNMelbourne, Victoria, 3065, Australia
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Summa Health Clinical Research Center
RECRUITINGAkron, Ohio, 44304, United States
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Temple University Hospital
RECRUITINGPhiladelphia, Pennsylvania, 19140, United States
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The Alfred Hospital
RECRUITINGMelbourne, VC, 3004, Australia
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The Chaim Sheba Medical Center
RECRUITINGRamat Gan, 6265601, Israel
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The Ohio State University
RECRUITINGColumbus, Ohio, 43210, United States
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The Royal Melbourne Hospital
RECRUITINGParkville, 3050, Australia
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The Tel Aviv Sourasky Medical Center
RECRUITINGTel Aviv, 64239, Israel
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Twoja Przychodnia Nowosolskie Centrum Medyczne
RECRUITINGNowa Sól, 67-100, Poland
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UMass Memorial Medical Center
WITHDRAWNWorcester, Massachusetts, 01655, United States
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UPMC Comprehensive Epilepsy Center
RECRUITINGPittsburgh, Pennsylvania, 15213, United States
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UTHealth Science Center at Houston
RECRUITINGHouston, Texas, 77030, United States
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Unidade Local de Saúde de Matosinhos
RECRUITINGMatosinhos Municipality, 4450-024, Portugal
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Universitaetsklinik fuer Kinder
RECRUITINGLinz, 4021, Austria
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Universitair Ziekenhuis Gent
RECRUITINGGhent, 9000, Belgium
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University California, Davis Clinical & Translation Science Center Clinical Research (CCRC)
WITHDRAWNSacramento, California, 95817, United States
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University College London Hospitals NHS Foundation Trust
RECRUITINGLondon, WC1N 3BG, United Kingdom
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University Hospital Center Zagreb
WITHDRAWNZagreb, 100 00, Croatia
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University Hospital Innsbruck
RECRUITINGInnsbruck, 6020, Austria
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University Hospital of Wales
RECRUITINGCardiff, Wales, CF14 4XW, United Kingdom
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University of Alabama - Strada Patient Care Center, Neurology
RECRUITINGMobile, Alabama, 36604, United States
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University of Arizona - Health Science Center
RECRUITINGTucson, Arizona, 85724, United States
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University of Arkansas for Medical Sciences
RECRUITINGLittle Rock, Arkansas, 72205, United States
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University of California, Irvine - Health Neurology Services
RECRUITINGOrange, California, 92868, United States
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University of Colorado Anschutz Medical Campus
WITHDRAWNAurora, Colorado, 80045, United States
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University of Kansas Medical Center
RECRUITINGKansas City, Kansas, 66160, United States
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University of Kentucky Albert B. Chandler Hospital (UK Healthcare)
RECRUITINGLexington, Kentucky, 40536, United States
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University of Maryland Medical Center
RECRUITINGBaltimore, Maryland, 21201, United States
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University of Michigan Hospitals
RECRUITINGAnn Arbor, Michigan, 48109, United States
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University of Pennsylvania
RECRUITINGPhiladelphia, Pennsylvania, 19104, United States
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University of South Florida
RECRUITINGTampa, Florida, 33606, United States
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University of Texas Health Science Center at San Antonio
RECRUITINGSan Antonio, Texas, 78229, United States
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University of Utah Clinical Neurosciences Center
ACTIVE_NOT_RECRUITINGSalt Lake City, Utah, 84132, United States
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University of Washington, Regional Epilepsy Center at Harborview Medical Center
RECRUITINGSeattle, Washington, 98104, United States
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Università Degli Studi Gabriele d'Annunzio Di Chieti
RECRUITINGChieti, 66100, Italy
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Universitätsklinik für Neurologie
RECRUITINGSalzburg, 5020, Austria
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Universitätsklinik für Neurologie, Medizinische Universität Wien
RECRUITINGVienna, 1090, Austria
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Universitätsklinikum Aachen
RECRUITINGAachen, D-52074, Germany
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Universitätsklinikum Frankfurt
RECRUITINGFrankfurt, 60528, Germany
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Universitätsklinikum Tübingen
RECRUITINGTübingen, 72076, Germany
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Universitätsklinikum Ulm
RECRUITINGUlm, 89081, Germany
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Vivantes Humboldt Klinikum
WITHDRAWNBerlin, 13509, Germany
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Wake Forest Baptist Health
RECRUITINGWinston-Salem, North Carolina, 27104, United States
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Wayne State University
RECRUITINGDetroit, Michigan, 48201, United States
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Xenoscience
RECRUITINGPhoenix, Arizona, 85004, United States
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