Updated to redefine the primary seizure types used to determine participant eligibility and conduct the primary/secondary endpoint analyses.

Updated total enrollment from 50-70 to approximately 70 participants; Updated total number of sites up to 45 sites; Added: Acceptable historical seizure data must include at least 12 consecutive weeks prior to the Screening visit of documenting seizure type and frequency (also noting seizure-free days); Added: If a participant must be abruptly discontinued from investigational product, (e.g., severe rash), careful attention should be paid for possibility of withdrawal symptoms such as increase in seizure number or severity. Consideration should be made by the investigator for providing another GABA-A medication for 1-2 weeks such as clobazam to mitigate the potential risk of withdrawal from a positive modulator of GABA-A; Added: Adverse event in which the character, severity or frequency is new in comparison to the participant’s existing risk profile with the exception of somnolence and seizures. Added: An Adverse Event that is associated with non-reversible target organ dysfunction, with the associated laboratory abnormalities as defined in exclusion criteria 11, 12 or 13. An allowance may be made for continued treatment if the abnormality is not medically significant; Added: A laboratory abnormality or vital sign change that is irreversible and considered medically significant, associated with use of the investigational product; Added: The Sponsor’s Medical Monitor does not have to be contacted to initiate unblinding in the IWRS system; Added: Baseline Visit – Randomization (Visit 2, Week 0 + 6 days) The following study procedures/assessments to be completed, the results received, and the investigator must ensure the participant meets all inclusion and exclusion criteria prior to IP administration. The 8 weeks between Screening and Randomization can be no less than 56 days and no more than 62 days.

Added: Exclusion Criteria - participants with ≤ 3 primary seizures during the 12- week baseline period; Added: If a participant fails to qualify because of Exclusion Criteria #4 (≤ 3 primary seizures during the 12-week baseline period), she will not be randomized. However, she can be rescreened after collecting another 12 or more weeks of seizure history that satisfies all eligibility criteria including Inclusion Criteria #5 and Exclusion Criteria #3. Each participant is allowed a maximum of 1 rescreening visit.

Added: As enrollment in the study was discontinued early due to administrative reasons, and only 15 biomarker-positive participants are expected to be randomized, the study is not considered to have adequate power for formal testing of the statistical hypotheses. Since the reason for stopping enrollment is external to the study, the statistical analysis will be performed as planned. All p-values produced as part of the pre-specified analysis would therefore be considered as nominal; Added: In the event of unforeseen circumstances, in-person study visit assessments may not be able to be performed. To conduct the study according to protocol while preserving patient safety, operational alternatives such as those listed below can be employed as long as the site’s actions are in compliance with the institution’s IRB/EC policies and regulations: Telemedicine visits (video and/or audio communication methods); In-home visits; Local physician visits; Use of local and/or off-site laboratories; Site-to-patient IP distribution. Added: Retrospective entry of diary events (seizure and medication) can be completed by the caregiver up to 5 days later and proxy entry by the site is also available to the site staff (greater than 5 days), but neither method is encouraged.