Key Inclusion Criteria:  The participant must have had the responsive neurostimulation system (RNS®) System implanted for more than 1 year and medically intractable focal onset epileptic seizures (history of persistent seizures refractory to 2 or more anti-epileptic drugs [AEDs]), with seizures from all foci represented in the implanted RNS electrodes. The participant is required to have a continuous period of at least 2 months with constant RNS detection and stimulation settings as well as stable AED (that is, 60 days with no dose adjustments of more than 25%) as determined by medical history and the Patient Data Management System (PDMS). The participant has more or equal to 7 long episodes per month. The participant is required to have a demonstrated history of compliance with RNS scanning and uploading procedure in the past year (less than 20% missing data on the PDMS).  Key Exclusion Criteria:  The participant has the RNS System implanted in other regions than the epileptic foci such as the thalamus. The participant has a RNS System with anticipated generator change in the coming 6 months. The participant has less than 7 long episodes and/or more than 20% variability in week to week rate during the prospective baseline period. The participant has or has had any clinically significant immunological, cardiovascular, respiratory, metabolic, renal, hepatic, gastrointestinal, endocrinological, haematological, dermatological, venereal, neurological (apart from epileptic diagnosis), or psychiatric disease or other major disorder, which in opinion of the investigator may influence efficacy or safety aspects in the study.  Other inclusion and exclusion criteria may apply.