Key Inclusion Criteria:

1. Male or Female, age ≥18 to ≤75
2. Focal seizures, clinically defined as unilateral MTLE
3. Has failed to achieve seizure control despite adequate trials of at least 2 ASDs at appropriate doses
4. Currently on stable doses (at least 1 month prior to Screening) of approved ASDs
5. Single seizure focus confirmed within one hippocampus
6. Seizure frequency averages ≥4 per 28-day period, including at least 2 clinical focal seizures per 28-day period with objective manifestations or more severe types, over the 6 months prior to the Screening Visit. (Phase 1/2 only)
7. Disabling seizure frequency of ≥2 per 28-day period averaged over 3 months prior to the Screening visit and over a prospective 10-week baseline period prior to Randomization (Phase 3 Only)

Key Exclusion Criteria:

1. Epilepsy due to other medical conditions and/or progressive neurologic disease
2. Evidence of seizure focus outside of the hippocampus or evidence of seizures of non- focal origin.
3. Significant other medical conditions which would impair safe participation
4. History of status epilepticus in the 3 years prior to screening.
5. Primary or secondary immunodeficiency
6. Suicide attempts in the past year 3 years
7. Severe psychiatric disorders
8. Prior lobectomy or LITT procedure
9. MRI indicating potential malignant lesion
10. Pregnancy, or currently breastfeeding.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 02/25/2026. Questions regarding updates should be directed to the study team contact.