A Randomized Controlled Trial of Cannabidiol (GWP42003-P, CBD) for Seizures in Tuberous Sclerosis Complex (GWPCARE6)

Key Inclusion Criteria: * Participant has a well-documented clinical history of epilepsy. * Participant has a clinical diagnosis of Tuberous Sclerosis Complex (TSC) according to the criteria agreed by the 2012 International TSC Consensus Conference. * All medications or interventions for epilepsy (including ketogenic diet and any neurostimulation devices for epilepsy) must have been stable for 1 month prior to screening and the participant is willing to maintain a stable regimen throughout the trial. Key Exclusion Criteria: * Participant has a history of pseudo-seizures. * Participant has clinically significant unstable medical conditions other than epilepsy. * Participant has an illness in the 4 weeks prior to screening or randomization, other than epilepsy, which in the opinion of the investigator could affect seizure frequency. * Participant has undergone general anesthetic in the 4 weeks prior to screening or randomization. * Participant has undergone surgery for epilepsy in the 6 months prior to screening. * Participant is being considered for epilepsy surgery or any procedure involving general anesthesia. * Participant has been taking felbamate for less than 1 year prior to screening. * Participant is taking an oral mTOR inhibitor. * Participant has any known or suspected hypersensitivity to cannabinoids or any of the excipients of the Investigational Medicinal Product (IMP), such as sesame oil. * Participant has any history of suicidal behavior or any suicidal ideation of type 4 or 5 on the C-SSRS in the last month or at screening. * Participant is currently using or has in the past used recreational or medicinal cannabis, or cannabinoid-based medications, within the 3 months prior to screening and is unwilling to abstain for the duration for the study. * Participant has tumor growth which, in the opinion of the Investigator, could affect the primary endpoint. * Participant has significantly impaired hepatic function at the screening or randomization visit * Participant has received an IMP within the 12 weeks prior to the screening visit.