Randomized, Double-Blind Study to Evaluate Efficacy and Safety of Cenobamate Adjunctive Therapy in PGTC Seizures

Brief Summary:
This trial is intended to study the safety and effectiveness of an new anti-epileptic drug (AED) on Primary Generalized Tonic-Clonic (PGTC) Seizures. Eligible Subjects will continue to take their usual AEDs and receive either cenobamate or placebo. Subjects will have a 50% chance or receiving cenobamate or placebo (sugar pill). Subjects will initially receive 12.5 mg of cenobamate or placebo (study drug) and increase the dose every two weeks until they reach a target dose of 200 mg. Subjects will take study drug at approximately the same time in the morning (once a day) with or without food. If tolerability issues arise, dosing can be changed to evening. Also, once a subject reaches 200 mg of study drug, the dose can be decreased one time to 150 mg, if necessary. The treatment period is 22 weeks and there is a 3 week follow up period, which includes a one week decrease in study drug to 100 mg prior to stopping. Subjects who complete may be eligible for an extension study and will not have to complete the follow up period. Subjects will track their seizure types and frequency in a diary throughout the study.

Detailed Description:
This randomized, double-blind, placebo controlled trial is designed to look at safety and efficacy of cenobamate adjunctive therapy as compared to placebo on PGTC seizures in subject with idiopathic generalized epilepsy. Subjects will be randomized to receive either cenobamate or placebo on a 1:1 basis. The study will have three periods, pre-randomization period where a baseline seizure frequency is established, treatment period and follow up period. The treatment period consists of a 10 week titration phase where subjects are titrated slowly until they reach the target dose and a maintenance phase. During the titration phase, subjects will receive 12.5 mg study drug, followed by 25 mg, 50 mg, 100 mg, and 150 mg study drug every two weeks. During the maintenance phase, subjects will receive the target dose of 200 mg study drug. Subjects will take their once daily dose of study drug at approximately the same in the morning with or without food. If tolerability issues arise, subjects can switch to evening dosing. There is also an option to down-titrate to 150 mg study drug, one time only. If tolerability issues continue, subjects may be discontinued. Upon completion of the maintenance phase, eligible subjects will have an opportunity to enroll in an open-label safety study. Subjects who discontinue early or do not wish to participate in this additional study will complete the three week follow up period. Subjects may receive a one week down titration to 100 mg and return for a follow up visit 2 weeks later.

Throughout the study, subjects will keep a diary containing the type and frequency of seizures. This will be the primary efficacy measure.


Study Type: Interventional  (Clinical Trial)
Estimated Enrollment: 152 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Study to Evaluate the Efficacy and Safety of Cenobamate Adjunctive Therapy in Subjects With PGTC Seizures
Actual Study Start Date: September 21, 2018
Estimated Primary Completion Date: November 2021
Estimated Study Completion Date: November 2021

Arms:
- Experimental: Cenobamate
- Placebo Comparator: Placebo