Study terminated due to enrollment challenges during COVID-19 pandemic.

To determine the safety and tolerability of GWP42006 (cannabidivarin, CBDV) in children and young adults with autism spectrum disorder (ASD) and to examine the effect of GWP42006 on communication, social interactions, sleep, behavior, and cognition profiles.

This is a 52-week, open-label trial to evaluate the safety and tolerability of GWP42006. Participants who satisfy all eligibility criteria will start GWP42006 at a dose of 2.5 milligrams per kilogram per day (mg/kg/day) and titrate to a target dose of 10 mg/kg/day or 800 mg/day, whichever is smaller, during the first 4 weeks of treatment. If there is intolerance during titration, the participant may be maintained on a dose below 10 mg/kg/day. The maximum dose participants aged 6 years or older can receive will be 20 mg/kg/day or 1600 mg/day, whichever is smaller. Following the final treatment dose, participants will taper GWP42006 10% per day. The investigator will withdraw participants who fail to demonstrate any perceived benefit and may withdraw participants for whom tolerability is poor.

Key Inclusion Criteria:

• Diagnosis of Autism Spectrum Disorder (ASD) as defined by the Autism Diagnostic Observation Schedule, 2nd Edition and The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition
• Intelligence quotient (IQ) of 40-120 (inclusive)
• Participant and their caregiver are English speaking.
• In the opinion of the investigator, the participant presents with ASD symptoms that warrant a therapeutic trial with GWP42006.

Key Exclusion Criteria:

• Known single gene neurogenetic disorder with high rates of epilepsy/autism (e.g., fragile X, tuberous sclerosis complex), structural brain lesion (prior stroke or hemispheric brain malformations), or history of any other epileptic encephalopathy, including infantile spasms, before the diagnosis of ASD
• More than 2 epileptic seizures per month within the 6 months prior to screening
• Initiation of a behavioral therapy program, new psychotropic medication, or therapeutic diet within the 2 months prior to screening, or plan to change or start any of the above during the trial
• Presence of a significant untreated medical problem (obstructive sleep apnoea, restless legs syndrome, gastroesophageal reflux disease, etc.) which may have significant impact on sleep study measures
• Behavioral management issues (e.g., self-injury, aggression) severe enough to be of safety concerns (to participant and/or staff)
• Clinically significant electrocardiogram abnormality or postural drop in systolic blood pressure at screening
• Any known or suspected hypersensitivity to cannabinoids or any of the excipients of GWP42006, such as sesame oil
• Known history of psychiatric disorder (defined as schizophrenia, bipolar disorder, or other psychiatric disease with a known history of hallucinations or delusions)
• History of any inborn errors of metabolism
• Significantly impaired hepatic function at screening
• Received an investigational product within the 3 months prior to screening
• Participant has been taking felbamate for less than 1 year prior to screening
• History of substance use disorders or positive drug of abuse dipstick test at screening (unless the positive result is due to a known concomitant medication)
• Currently using or has used recreational or medicinal cannabis or cannabinoid-based medications within the 3 months prior to screening and is unwilling to abstain for the duration of the trial
• Any history of suicidal behavior or any suicidal ideation within the month prior to or at screening