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Study on the Effects of XEN1101 and Placebo for Patients with Primary Generalized Tonic-Clonic Seizures

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effects of a medication called XEN1101 on individuals who experience Primary Generalized Tonic-Clonic Seizures. These seizures are a type of epilepsy that involves sudden and severe muscle contractions and loss of consciousness. The study aims to evaluate how well XEN1101 can reduce the frequency of these seizures when used alongside other treatments.

Participants in the study will be randomly assigned to receive either XEN1101 or a placebo, which is a capsule that looks like the medication but does not contain the active substance. The medication is taken orally in the form of a capsule. The study will last for a period of 12 weeks, during which the safety and effectiveness of XEN1101 will be closely monitored. The goal is to see if the medication can help reduce the number of seizures experienced by participants.

The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual medication and who is receiving the placebo. This helps ensure that the results are unbiased. The trial will also assess how well participants tolerate the medication and any potential side effects. The ultimate aim is to determine if XEN1101 can be a beneficial addition to existing treatments for those suffering from Primary Generalized Tonic-Clonic Seizures.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, you will be informed about the nature and risks involved. You will need to provide written consent to participate. If you are a minor, your legal representative or parent will provide consent on your behalf.

  2. Step 2

    Initial assessment

    An initial assessment will be conducted to ensure you meet the study's eligibility criteria. This includes confirming your medical history of primary generalized tonic-clonic seizures and reviewing any previous treatments you have received.

  3. Step 3

    Baseline period

    During the baseline period, you will continue your current treatment regimen. You will be required to keep an accurate diary of your seizures. This period helps establish a baseline for your seizure frequency before starting the study medication.

  4. Step 4

    Randomization

    You will be randomly assigned to receive either the study medication XEN1101 or a placebo. This process is double-blind, meaning neither you nor the study team will know which treatment you are receiving.

  5. Step 5

    Treatment phase

    During the treatment phase, you will take the assigned medication orally in the form of a capsule. The dosage and frequency will be determined by the study protocol. You will continue to record your seizure activity in a diary.

  6. Step 6

    Follow-up visits

    You will attend regular follow-up visits with the study team. These visits are designed to monitor your health, assess the effectiveness of the treatment, and address any side effects you may experience.

  7. Step 7

    End of study

    At the end of the study, a final assessment will be conducted. You will discuss your experience with the study team, and any necessary follow-up care will be arranged.

Who can join the trial?

14 criteria

  • The person must understand the study and its risks and agree to participate by signing a consent form. If the person is a minor, their legal guardian or parent must give consent.
  • The person must agree to follow the study's rules about birth control.
  • Men must agree not to donate sperm from the start of the study until 3 months after the last dose of the study drug. Women must agree not to donate eggs from the start of the study until 6 months after the last dose of the study drug.
  • The person must have had a routine EEG (a test that measures brain activity) within 5 years before the study starts or during the initial phase of the study.
  • If the person has a device like a vagal nerve stimulator, it must have been implanted at least 5 months before the study starts, and the device settings should not change 30 days before the study and during the study.
  • The person must be able to participate for the entire duration of the study.
  • The person must have had probable or possible Primary Generalized Tonic-Clonic Seizures (PGTCS) for at least 1 year, as per specific medical guidelines, and be approved by the study committee.
  • The person must be on a stable dose of 1 to 3 allowed seizure medications for at least 1 month before the study starts and throughout the study.
  • The person must be able to keep accurate records of their seizures.
  • The person must be at least 12 years old and have a Body Mass Index (BMI) of 40 or less at the start of the study.
  • The person must have tried at least 2 different seizure medications at proper doses without achieving long-term seizure freedom.
  • The person must have started having PGTCS before the age of 40.
  • The person must have had a brain scan (CT or MRI) within the last 10 years after their seizures began, and the results must be available.
  • The person must have had at least 3 PGTCS in the 8 weeks before the study starts, confirmed by a seizure diary or reliable report from the person or their caregiver.

Who cannot join the trial?

9 criteria

  • Patients who do not have Primary Generalized Tonic-Clonic Seizures cannot participate. These are a type of seizure that affects the whole brain and causes convulsions.
  • Patients who are not within the specified age range cannot participate. The age range includes children, adolescents, and adults.
  • Patients who are not willing or able to follow the study procedures cannot participate.
  • Patients who are pregnant or breastfeeding cannot participate.
  • Patients with other significant health issues that might interfere with the study cannot participate.
  • Patients who are currently participating in another clinical trial cannot participate.
  • Patients who have a history of drug or alcohol abuse cannot participate.
  • Patients who have had a recent major surgery cannot participate.
  • Patients who have a known allergy to the study medication cannot participate.
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Investigated drugs

XEN1101 is a medication being studied to see if it can help reduce the number of seizures in people who have a specific type of seizure called Primary Generalized Tonic-Clonic Seizures (PGTCS). This medication is used in addition to other treatments that the patient might already be taking for their seizures. The goal of using XEN1101 is to see if it can make these seizures happen less often, making it easier for patients to manage their condition. The study is designed to compare the effects of XEN1101 with a placebo to understand how well it works and how safe it is for patients.

What is already known about the treatment

XEN1101 – XEN1101 is administered orally in the form of tablets and is currently being studied in clinical trials as an additional treatment for people experiencing Primary Generalized Tonic-Clonic Seizures, a type of seizure that affects the entire brain. The medication is in the advanced stages of research, specifically a Phase 3 clinical trial, which means it is being tested for safety and effectiveness in a larger group of patients. XEN1101 works by targeting specific channels in the brain that help control electrical activity, aiming to reduce the frequency of seizures. It is classified as an anticonvulsant, a type of drug used to prevent or reduce the severity of epileptic seizures.

Investigated diseases

Primary Generalized Tonic-Clonic Seizures – Primary Generalized Tonic-Clonic Seizures are a type of epilepsy characterized by sudden and severe convulsions. These seizures involve both sides of the brain from the onset and typically result in a loss of consciousness. The progression of the seizure includes a tonic phase, where the body becomes rigid, followed by a clonic phase, where the body experiences rhythmic jerking movements. These seizures can occur without warning and may last for several minutes. After the seizure, individuals often experience confusion, fatigue, and muscle soreness. The frequency and severity of these seizures can vary among individuals.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2022-502286-16-00Protocol codeXPF-010-303Estimated enrolment172 patientsSponsorXenon Pharmaceuticals Inc.

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