Safety and Efficacy Study of Cenobamate in Pediatric Subjects 2-17 Years of Age With Partial-onset (Focal) Seizures

Inclusion Criteria:

1. Have a diagnosis of epilepsy with partial-onset (focal) seizures (POS) with orwithout secondarily generalized seizures according to the International LeagueAgainst Epilepsy's (ILAE) Classification of Epileptic Seizures. A diagnosis shouldhave been established at least 12 months prior to Visit 1 (Screening) by clinicalhistory and an electroencephalogram (EEG) that is consistent with the diagnosis;normal interictal EEGs will be allowed provided that the participant meets the otherdiagnosis criterion (i.e., clinical history)

2. Male or female participant, from age 2 to less than 18 years at the time of informedconsent/assent (dates including informed consent in YKP3089C039)

3. Have a minimum weight of 10.0 kilograms (kg) (22.0 pounds [lb])

4. Have had a brain imaging (e.g., magnetic resonance imaging [MRI] scan or computedtomography (CT) within 10 years before Visit 1 (Screening) that ruled out aprogressive cause of epilepsy.

5. For subjects new to Study YKP3089C040, participants must have had at least 1 POSseizure during the 28-day Baseline Period. Only simple POS with motor signs, complexPOS, and complex POS with secondary generalization are counted toward this inclusionfor POS

6. Are currently being treated with stable doses of 1 to a maximum of 3 approvedantiepileptic drugs (AEDs). Doses must be stable for at least 4 weeks before toVisit 1 (Screening). A vagal nerve stimulator [VNS] will not be counted as one ofthe 3 allowed AEDs but the settings should be stable for at least 4 weeks prior toVisit 1 (Screening).

7. Investigator believes subject could benefit from new or continued exposure to studydrug

8. Subjects entering from study YKP3089C039 must continue to meet all of the inclusioncriteria from the YKP3089C039 study

9. Subjects receiving felbamate as a concomitant AED must meet the following criteria:

10. Have a 12-month history of felbamate use and a history of a fixed dosingregimen for a minimum of 60 days prior to Visit 1 (Screening).

11. No prior or known history of hepatotoxicity or hematologic disorder due tofelbamate.

12. Subjects following a ketogenic diet will be allowed as long as the diet has beenstable for at least 30 days prior to Visit 1 (Screening) and will remain stable forthe duration of the study

Exclusion Criteria:

1. Females who are breastfeeding or pregnant at Screening or Baseline.

2. Current or history of pseudo-seizures (psychogenic nonepileptic seizures) withinapproximately 2 years before Visit 1 (Screening).

3. Have a history of status epilepticus that required hospitalization during the 6months before Visit 1 (Screening).

4. Have an unstable psychiatric diagnosis that may confound participants' ability toparticipate in the study or that may prevent completion of the protocol-specifiedtests (e.g., significant suicide risk, including suicidal behavior and ideationwithin 6 months before Visit 1 (Screening), current psychotic disorder, acutemania).

5. Any suicidal ideation with intent, with or without a plan within 6 months beforeVisit 2 [i.e., answering "Yes" to questions 4 or 5 on the Suicidal Ideation sectionof the Columbia-Suicide Severity Rating Scale (C-SSRS) in participants aged 6 andabove, if able].

6. Are scheduled and/or confirmed to have epilepsy surgery within 6 months after Visit 1 (Screening); however, those who have previously documented "failed" epilepsysurgery will be allowed.

7. Evidence of clinically significant disease (e.g., cardiac, respiratory,gastrointestinal, renal disease) that in the opinion of the investigator(s) couldaffect the participant's safety or interfere with the study assessments.

8. Presence of only nonmotor simple partial seizures or primary generalized epilepsies.

9. Evidence of moderate or severe renal insufficiency as defined by estimatedglomerular filtration rates (eGFRs) of 31 to < 60 "milliliters per minute (mL/min)"and < 30 mL/min, respectively.

10. Evidence of significant active hepatic disease. Stable elevation of liver enzymes,alanine aminotransferase (ALT) and aspartate aminotransferase (AST) due toconcomitant medication(s), will be allowed if they are less than 3 times the upperlimit of normal (ULN).

11. Evidence of significant active hematological disease; white blood cell (WBC) countequal or less than 2500/µL (2.50 1E+09/liter [L]) or an absolute neutrophil countequal or less than 1000/µL (1.00 1E+09/L).

12. Subjects with Familial short QT syndrome.

13. Clinically significant electrocardiogram (ECG) abnormality, including prolongedcorrected QT interval (QTc) defined as greater than 450 milliseconds (msec) orshortened corrected QT interval (QTc) defined as less than 340 msec.

14. Have a progressive central nervous system (CNS) disease, including degenerative CNSdiseases and progressive tumors.

15. Subject has a history of any serious drug-induced hypersensitivity reaction (including, but not limited to, Stevens Johnson syndrome, toxic epidermalnecrolysis, or DRESS) or any drug-related rash requiring hospitalization.

16. History of AED-associated rash that involved conjunctiva or mucosae.

17. History of more than one non-serious drug-related hypersensitivity reaction thatrequired discontinuation of the medication.

18. Concomitant use of vigabatrin. Participants who took vigabatrin in the past must beoff vigabatrin for at least 5 months before Visit 1 (Screening) and withdocumentation showing no evidence of a vigabatrin-associated clinically significantabnormality in a visual perimetry test.

19. A history of intermittent use of rescue benzodiazepines (i.e., 1 to 2 doses over a 24-hour period is considered a 1-time rescue) more than once within the 30 daysprior to Visit 1(Screening).

20. A VNS implanted less than 5 months before Visit 1 (Screening) or changes inparameter less than 4 weeks before Visit 1 (or thereafter during the study).

21. History of or a concomitant medical condition that in the opinion of theinvestigator(s) would preclude the participant's participation in a clinical studyor compromise the participant's ability to safely complete the study.

22. Have participated in a study involving administration of an investigational drug ordevice within 4 weeks before Visit 1 (Screening), or within approximately 5half-lives of the previous investigational compound, whichever is longer.

23. Participants with rare hereditary problems of galactose intolerance, the Lapplactase deficiency or glucose-galactose malabsorption.

24. For subjects new to Study YKP3089C040 previous exposure to cenobamate orsensitivity/allergy to components of the oral suspension.