The trial is taking place at:

Michigan State University | Department of Neurology

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An Open-label Study of XEN1101 in Epilepsy (X-TOLE4)


Xenon Pharmaceuticals

Status and phase

Phase 3


Tonic-Clonic Seizures
Focal Epilepsy


Drug: XEN1101

Study type


Funder types




Details and patient eligibility


This study will evaluate the long term safety, tolerability, PK, and efficacy of XEN1101 25 mg QD taken orally in subjects with Focal Onset Seizures (FOS) or Primary Generalized Tonic-Clonic Seizures (PGTCS) for the treatment of seizures for up to 3 years.

Full description

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 25 mg QD taken orally once daily (QD) in subjects with FOS or PGTCS for the treatment of seizures for up to 3 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 3 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. All subjects will be initially assigned to receive 25 mg QD of XEN1101. Subjects will be instructed to orally take XEN1101 once daily 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.


880 estimated patients




18+ years old


No Healthy Volunteers

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.
  2. Subject must have successfully completed the 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 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.

Trial design

Primary purpose




Interventional model

Single Group Assignment


None (Open label)

880 participants in 1 patient group

XEN1101 25 mg/day
Experimental group
XEN1101 25 mg/day
Drug: XEN1101

Trial contacts and locations



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