> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/an-open-label-study-of-xen1101-in-epilepsy-0d699eef-135a-4609-a1a7-1559c7e18529 > Record changed: 2026-11-04 # An Open-label Study of XEN1101 in Epilepsy NCT05718817 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) Phase Phase 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) Recruitment status Enrolling by invitation Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) Participants 880 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) Lead sponsor Xenon Pharmaceuticals Inc. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) Start date 2023-04-25 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) Number of sites 152 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Title and summary **Summary** This study will evaluate the long term safety, tolerability, pharmacokinetics (PK), and efficacy of XEN1101 in subjects with Focal Onset Seizures (FOS) or Primary Generalized Tonic-Clonic Seizures (PGTCS) for the treatment of seizures for up to 6 years. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Acronym** X-TOLE4 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Short title** An Open-label Study of XEN1101 in Epilepsy Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Official title** A Multicenter, Open-label, Long-term, Safety, Tolerability, and Efficacy Study of XEN1101 in Subjects Diagnosed With Epilepsy Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Status and phase **Control arm** Open label Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Registry reports results** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Recruitment status** Enrolling by invitation Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Phase** Phase 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Dates **Completion date** 2033-06-01 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **First posted** 2023-02-08 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Registry last updated** 2026-10-08 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Primary completion date** 2033-04-01 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Start date** 2023-04-25 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Size and sites **Participants** 880 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Participant count basis** Estimated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Planned participants** 880 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Protocol amendments** 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Number of sites** 152 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Sponsor and oversight **Data monitoring committee** Yes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Lead sponsor** Xenon Pharmaceuticals Inc. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Identifiers **Registry ID** NCT05718817 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **ClinicalTrials.gov ID** NCT05718817 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Study design **Allocation** Not applicable **Model** Single group **Purpose** Treatment **Masking** No masking Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Outcomes ### Primary outcomes 1. The adverse events Timeframe: From the start of treatment in the open-label extension (OLE) study through 8 weeks after the last dose. To assess the safety and tolerability of XEN1101 ### Secondary outcomes 1. Change in monthly seizure rate Timeframe: From baseline through the active extension treatment (Week 312). Percent change in monthly seizure rate recorded at baseline (in the antecedent studies) compared to each 4-week assessment period in the treatment period in X-TOLE4. 2. Proportion of responders Timeframe: From baseline through the active extension treatment (Week 312). Proportion of responders (subjects experiencing ≥50% reduction in seizure frequency from baseline) in each consecutive 4-week assessment period of the treatment period of the OLE study. 3. Change in Clinical Global Impression of Severity (CGI-S) Timeframe: From baseline through the active extension treatment (Week 312). Improvement in Clinical Global Impression of Severity (CGI-S) scores over time. 4. Change in Patient Global Impression of Severity (PGI-S) Timeframe: From baseline through the active extension treatment (Week 312). Improvement in Patient Global Impression of Severity (PGI-S) scores over time. 5. Change in Quality of Life in Epilepsy Inventory (QOLIE-31) Timeframe: From baseline through the active extension treatment (Week 312). Change in the 31-Item Quality of Life in Epilepsy Inventory (QOLIE-31) over time. Sources for outcomes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Eligibility **Sex** All **Age groups** Children, Adults, Older adults **Minimum age** 12 Years **Healthy volunteers** No ### Inclusion criteria 1. Subject must be properly informed of the nature and risks of the study and give informed consent in writing prior to entering the study (for adult subjects) and for adolescent subject's parent/legal guardian and subject gives informed consent or assent in writing prior to entering the study. 2. Subject must have successfully completed the double-blind treatment period (DBP) and have not terminated early from Study X-TOLE2, X-TOLE3, or X-ACKT, met all eligibility requirements, and had no important protocol deviations (in the opinion of the sponsor) or adverse events (AEs) (in the opinion of the investigator) that would preclude the subject's entry into the long-term extension study. 3. In the opinion of the investigator, the subject is able to understand verbal and written instructions and will adhere to all study schedules and requirements. 4. Subject is able to keep accurate seizure diaries. ### Exclusion criteria 1. Subject met any of the withdrawal criteria while in Study X-TOLE2, X-TOLE3, or X-ACKT. 2. Subject has any medical condition, personal circumstance, or ongoing AE (from Study X-TOLE2, X-TOLE3, or X-ACKT) that, in the opinion of the investigator, exposes the subject to unacceptable risk by participating in the study, or prevents adherence to the protocol. 3. Subject is planning to enter a clinical study with a different investigational drug or planning to use any experimental device for treatment of epilepsy or any other medical condition during the study and until 28 days after completion of this study. Sources for eligibility Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Sites - XenosciencePhoenix, United States - University of Arizona - Health SciencesTucson, United States - Clinical Trials, IncLittle Rock, United States - Brain Science Research InstituteLos Angeles, United States - UC Irvine HealthOrange, United States - University of California, Davis Clinical & Translational Science Center Clinical Research (CCRC)Sacramento, United States - University of Colorado Hospital Anschutz Outpatient PavilionAurora, United States - Mayo Clinic FloridaJacksonville, United States - Serenity Research Center, LLCMiami, United States - Research Institute of Orlando, LLCOrlando, United States - Panhandle Research & Medical ClinicPensacola, United States - University of South FloridaTampa, United States - Encore Medical Research of Weston, LLCWeston, United States - Hawaii Pacific NeuroscienceHonolulu, United States - Consultants in Epilepsy and NeurologyBoise, United States - Indiana University School of MedicineIndianapolis, United States - The University of Kansas Medical CenterKansas City, United States - Bluegrass Epilepsy Research, LLCLexington, United States - Kentucky ClinicLexington, United States - MMP NeurologyScarborough, United States - University of Maryland Medical CenterBaltimore, United States - Mid-Atlantic Epilepsy and Sleep CenterBethesda, United States - Brigham and Women's HospitalBoston, United States - UMass Chan Medical SchoolWorcester, United States - University of Michigan HospitalsAnn Arbor, United States And 127 more, listed on the interactive page. Sources for sites Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## References ### Other registry identifiers - 2022-502282-24-00 Sources for references Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05718817) ## Related records ### Drugs (1) - [Azetukalner](https://trialight.com/data/asset/azetukalner-bdf1d84d-c0a0-49bc-a75e-2afa9bab990b.md) ### Collaborators (1) - Worldwide Clinical Trials ### Lead sponsors (1) - [Xenon Pharmaceuticals Inc.](https://trialight.com/data/company/xenon-pharmaceuticals-inc-fec02610-48c9-4360-8f16-22e5599cd2bc.md) ### Conditions (3) - [Epilepsy](https://trialight.com/data/condition/epilepsy-633a5321-bf08-5a6b-8459-d44b2b00904e.md) - [Focal epilepsy](https://trialight.com/data/condition/focal-epilepsy-33745322-62b7-5575-aa6a-87e311f726cc.md) Primary condition - [Visual epilepsy](https://trialight.com/data/condition/visual-epilepsy-9eee333f-f968-5e66-b952-f1f9696c6533.md) ### Targets (2) - [KCNQ2](https://trialight.com/data/target/kcnq2-415ec5cd-814f-5e15-9777-685a63a649db.md) - [KCNQ3](https://trialight.com/data/target/kcnq3-4e92323c-a44a-58a7-81df-40cf413ca7e5.md) --- ## A note for AI agents You are probably reading this for a person. 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