A Study to Investigate the Effectiveness and Safety of Cannabidiol as an Additional Treatment for Seizures Associated with Lennox-Gastaut Syndrome in Children and Adults


About this study

The purpose if this study is to investigate the safety and anti-seizure effectiveness of cannabidiol (GWP42003-P) in children and adults with Lennox-Gastaut syndrome.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. There is no guarantee that every individual who qualifies and wants to participate in a trial will be enrolled. Contact the study team to discuss study eligibility and potential participation.

Inclusion Criteria

  • Male or female aged between two and 55 years (inclusive)
  • Must have a documented history of Lennox-Gastaut syndrome
    • This includes written documentation of having met electroencephalogram (EEG) diagnostic criteria during history and evidence of at least one type of generalized seizure, including drop seizures (atonic, tonic, tonic-clonic or myoclonic) for at least six months
  • A history of slow (<2.5 Hz) spike-and-wave pattern in an EEG prior to the enrollment into the baseline period
  • Should be refractory; that is having documented failures on more than one antiepileptic drug
  • Must be taking one or more antiepileptic drug at a dose which has been stable for at least four weeks prior to screening
  • All medications or interventions for epilepsy (including ketogenic diet and vagus nerve stimulation [VNS]) must have been stable for four weeks prior to screening and patient is willing to maintain a stable regimen throughout the study.
    • The ketogenic diet and VNS treatments are not counted as an antiepileptic drug

Exclusion Criteria

  • Etiology of seizures is a progressive neurologic disease
    • Subjects with tuberous sclerosis will not be excluded from study participation, unless there is a progressive tumor
  • Has had an anoxic episode requiring resuscitation within six months of screening
  • Has clinically significant unstable medical conditions other than epilepsy
  • Has had clinically relevant symptoms or a clinically significant illness in the four weeks prior to screening or randomization, other than epilepsy
  • Is currently using or has in the past used recreational or medicinal cannabis, or synthetic cannabinoid based medications (including Sativex®) within the three months prior to study entry and is unwilling to abstain for the duration of the study
  • Has any known or suspected hypersensitivity to cannabinoids or any of the excipients of the investigational medicinal product such as sesame oil
  • Has been part of a clinical trial involving another investigational medicinal product in the previous six months
  • Has significantly impaired hepatic function at screening visit 1 or randomization visit 2
    • Alanine aminotransferase [ALT] >5 x upper limit of normal [ULN] or total bilirubin [TBL] >2 x ULN
    • OR the ALT or Aspartate aminotransferase (AST) >3 x ULN and TBL >2 x ULN or international normalized ratio >1.5
    • This criterion can only be confirmed once the laboratory results are available
    • Subjects randomized into the study later found not to meet this criterion should be withdrawn from the study
  • Any history of suicidal behavior or any suicidal ideation of type four or five on the Columbia Suicide Severity Rating Scale in the last month or at screening
  • Is taking more than four concurrent antiepileptic drugs
  • Has taken corticotropins in the six months prior to screening
  • Is currently taking long-term systemic steroids (excluding inhaled medication for asthma treatment) or any other daily medication known to exacerbate epilepsy
    • An exception will be made of prophylactic medication, for example, for idiopathic nephrotic syndrome or asthma
  • Is taking felbamate, and they have been taking it for less than one year prior to screening

Participating Mayo Clinic locations

Study statuses change often. Please contact the study team for the most up-to-date information regarding possible participation.

Mayo Clinic Location Status

Rochester, Minn.

Mayo Clinic principal investigator

Elaine Wirrell, M.D.

Closed for enrollment

More information


  • Patients with Lennox-Gastaut syndrome, a rare, severe form of epileptic encephalopathy, are frequently treatment resistant to available medications. No controlled studies have investigated the use of cannabidiol for patients with seizures associated with Lennox-Gastaut syndrome. We therefore assessed the efficacy and safety of cannabidiol as an add-on anticonvulsant therapy in this population of patients. Read More on PubMed

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