Study Evaluating the Safety and Efficacy of RAP-219 in Adult Participants With Refractory Focal Epilepsy

Inclusion Criteria: * Medically refractory focal epilepsy with an implanted responsive neurostimulator device placed correctly in a seizure onset zone that meet several device-related criteria and demonstrated history of compliance with interrogation of the RNS device and upload of data * If currently treated with antiseizure medications, up to a maximum of 4 concomitant mediations are allowed * At least 1 clinical seizure during the 8-week retrospective eligibility period * Participants in otherwise good health as determined by the investigator * Willing and able to adhere to all aspects of the protocol * A demonstrated history of compliance with interrogation of the RNS device and upload of data before screening Exclusion Criteria: * Participants with generalized onset seizures in the past 10 years * History of status epilepticus while on antiseizure medications within 2 years of screening * Individuals of reproductive potential who do not agree to simultaneously use two effective birth-control methods * Participants who have had epilepsy surgery within the last 12 months before screening