A Long-term Study of the Safety and Effectiveness of RAP-219 in Adults With Focal Onset Seizures

This is a multi-center, open-label study to evaluate the long-term safety, tolerability, pharmacokinetics, pharmacodynamics and antiseizure activity of RAP-219 in adult participants with refractory focal seizures

• RAP-219 (Drug): Participants will receive one RAP-219 0.125 mg capsule daily for 3 days followed by one 0.25mg tablet RAP-219 daily for 28 days, then one 0.75mg tablet daily for the remainder of the treatment period.

Primary outcomes

• Incidence of treatment-emergent adverse events (TEAEs) [From the start of RAP-219 treatment through 8 weeks after last dose, up to Week 112]

Secondary outcomes

• Percent change in clinical seizure frequency [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Group median percent change in clinical seizure frequency per 28-day period as reported in a clinical seizure diary
• Clinical seizure 25%, 50%, 75%, and 100% responder proportions [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Proportion of participants with at least 25%, 50%, 75%, or with 100% reduction in clinical seizure frequency per 28-day period as reported in a clinical seizure diary
• Change in clinical seizure-free day frequency [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Group median change in clinical seizure-free day frequency per 28-day period as reported in a clinical seizure diary
• Longest clinical seizure-free interval [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Duration, in days, of the longest continuous period of clinical seizure-free days per period as reported in a clinical seizure diary
• Time to pre-randomization clinical seizure count [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Duration, in days, between the beginning of the open-label treatment period and the nth clinical seizure, where n is the number of clinical seizures per 28-day period during the prospective pre-treatment baseline period, as reported in a clinical seizure diary
• RNS long episode 30%, 50%, 75% or with 100% responder proportions [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Proportion of participants with at least 30%, 50%, 75%, and 100% reduction in long episodes per 28-day period as recorded by the RNS® System
• Percent change in RNS long episode frequency [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Group median percent change in long episode frequency per 28-day period as recorded by the RNS® System
• Change in RNS long episode-free day frequency [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Group median change in long episode-free day frequency per 28-day period as recorded by the RNS® System
• Longest RNS long episode-free interval [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Duration, in days, of the longest continuous period of long episode-free days per period as recorded by the RNS® System
• Time to pre-randomization long episode count [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Duration, in days, between the beginning of the open-label treatment period and the mth long episode, where m is the number of long episodes per 28-day period during the pre-treatment baseline period, as recorded by the RNS® System
• Percent change in RNS estimated electrographic seizure frequency [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Group median percent change in estimated electrographic seizure frequency per 28-day period as recorded by the RNS® System
• Clinical Global Impression of Change (CGI-C) responder count and proportions [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Count and proportion of participants with any improvement (minimally improved, much improved, or very much improved) or clinically meaningful improvement (much improved or very much improved) as reported on the Clinical Global Impression of Change (CGI-C) scale
• Patient Global Impression of Change [PGI-C] responder count and proportions [Throughout the open-label period until 8 weeks after the last dose, up to Week 112, compared to the pre-treatment baseline period.]: Count and proportion of participants with any improvement (minimally improved, much improved, or very much improved) or clinically meaningful improvement (much improved or very much improved) as reported on the Patient Global Impression of Change (PGI-C) scale

Sex: All, ages: 18 Years to 70 Years

Inclusion Criteria:

* Completion of the associated parent study (RAP-219-FOS-201) treatment period with acceptable tolerability, per Investigator.
* Diagnosis of refractory focal epilepsy
* Stable RNS(c) system settings
* A demonstrated history of compliance with RNS(c) system data interrogation and upload
* Good overall health other than focal epilepsy, per Investigator.
* BMI ≥ 18 kg/m\^2 and ≤ 45 kg/m\^2
* Willing and able to adhere to all aspects of the protocol.

Exclusion Criteria:

* Known of hypersensitivity to RAP-219
* Any clinically unstable or serious medical, neurological (other than epilepsy), psychological, or behavioral problem; laboratory or ECG finding that would increase participant risk or should otherwise exclude the patient from participation, as assessed by Investigator
* Pregnancy, lactation, or individuals of reproductive potential who do not agree to simultaneously use two effective birth-control methods

• Imran Quraishi, MD, Principal investigator, Yale University