• Failed to respond to at least 2 anti-seizure medications (ASMs) at appropriate dosages and duration.

• Disease specific criteria:

‣ diagnosis of FCD Type II based on clinical symptoms and confirmed by a positive magnetic resonance imaging (MRI)

⁃ diagnosis of TSC by either clinical or genetic diagnostic criteria (Northrup, 2021) as documented in the participant's medical record.

• Participant on average has had at least 8 countable/witnessed primary seizures during a 4-week baseline period with at least 1 seizure occurring in at least 3 of the 4 weeks of baseline

• All medical interventions for epilepsy / behavior (including ketogenic diet and any neurostimulation devices) should be stable for 28 days prior to screening with no more than 6 days per month use of rescue medication. Participants must remain on a stable regimen throughout the treatment period.

• Participant has had an MRI scan within 12 months of the planned date of first dose of study drug.