A Phase 3 interventional study of XEN1101 in Focal Epilepsy and Tonic-Clonic Seizures, sponsored by Xenon Pharmaceuticals Inc.. Enrolling by invitation at 153 sites in 25 countries. Open to participants aged 12 Years and older. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by Xenon Pharmaceuticals Inc. · Phase 3, Interventional, and Treatment
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.
This is an Open Label Extension study of the following Phase 3 clinical studies: XPF-010-301 (X-TOLE2), XPF-010-302 (X-TOLE3), and XPF-010-303 (X-ACKT). This study will evaluate the long-term safety, tolerability, PK, and efficacy of XEN1101 in subjects with FOS or PGTCS for the treatment of seizures for up to 6 years. Subjects who successfully completed and did not terminate early from one of the antecedent studies (X-TOLE2, X-TOLE3, or X-ACKT) are eligible to participate in X-TOLE4.
Following enrollment into X-TOLE4, subjects will undergo a treatment period of up to 6 years, during which there will be a visit at 2-, 4-, and 13-weeks post-entry, with subsequent visits occurring at 13-week intervals during the first year, and then at 26-week intervals (with a telephone call in between) until dosing is completed.
Subjects will be initially assigned to XEN1101 as follows:
For subjects aged ≥12 and \<18 years
15 mg QD for those
Subjects will be instructed to orally take XEN1101 once daily (QD) with an evening meal. Subjects will be expected to keep a daily seizure eDiary with a minimum of 80% compliance for the duration of the extension study (reporting on ≥80% of days between visits).
Upon completion of dosing at the end of the treatment period, there will be an 8-week follow up period.
243 studies on the registry are indexed under Epilepsies, Partial; 49 are open to participants now.
This study's planned enrollment of 880 is above the median of 90 across 187 interventional studies indexed under Epilepsies, Partial.
Browse Epilepsies, Partial studies →Xenon Pharmaceuticals Inc. is the lead sponsor of 23 studies on the registry; 3 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
XEN1101 15 or 25 mg/day
Drug: XEN1101
XEN1101 capsules
Also known as: Azetukalner
The adverse events
To assess the safety and tolerability of XEN1101
Time frame: From the start of treatment in the open-label extension (OLE) study through 8 weeks after the last dose.
Change in monthly seizure rate
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.
Time frame: From baseline through the active extension treatment (Week 312).
Proportion of responders
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.
Time frame: From baseline through the active extension treatment (Week 312).
Change in Clinical Global Impression of Severity (CGI-S)
Improvement in Clinical Global Impression of Severity (CGI-S) scores over time.
Time frame: From baseline through the active extension treatment (Week 312).
Change in Patient Global Impression of Severity (PGI-S)
Improvement in Patient Global Impression of Severity (PGI-S) scores over time.
Time frame: From baseline through the active extension treatment (Week 312).
Change in Quality of Life in Epilepsy Inventory (QOLIE-31)
Change in the 31-Item Quality of Life in Epilepsy Inventory (QOLIE-31) over time.
Time frame: From baseline through the active extension treatment (Week 312).
Showing the first 100 of 153 sites across 25 countries. Choose a country and city above to see the rest.
Plan to share: No
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: XEN1101