An Efficacy and Safety Study of Clemizole HCl in Patients With Lennox-Gastaut Syndrome

This is a multicenter, Phase 3, randomized, double-blind, placebo-controlled study designed to evaluate the efficacy and safety of clemizole HCl as adjunctive therapy in children and adult participants with LGS.

The study will consist of an Observational Period, a Double-Blind (DB) Period, and an optional Open-Label Extension (OLE) Period.

Key Inclusion Criteria:

• Males or females, ages ≥2 to ≤55 years, at the time of Screening.
• Participant/parent/legal authorized representative (LAR) willing and able to give written informed consent/assent.
• Diagnosis of LGS, including:

• Evidence of at least one type of countable major motor seizure.
• History of electroencephalogram (EEG) consistent with LGS (abnormal background activity, and one of the following: 1) slow spike-wave discharges [<2.5 Hz], or 2) paroxysmal fast activity during sleep).
• Abnormal cognitive development.
• Onset of seizures at 11 years of age or younger.

Key Exclusion Criteria:

• Known sensitivity, allergy, or previous exposure to clemizole HCl.
• Known history of long QT syndrome or any significant history of a serious abnormality of the electrocardiogram (ECG) (e.g., recent myocardial infarction, clinically significant arrhythmia).
• Family history of sudden cardiac death, unexplained death, or death from a primary dysrhythmia potentially associated with QT prolongation in any family member.
• Seizures secondary to illicit drug or alcohol use, infection, neoplasm, demyelinating disease, degenerative neurological disease, or progressive central nervous system disease, metabolic illness, recent anoxic episode within the last 6 months requiring resuscitation, or progressive degenerative disease or any other condition, which in the opinion of the investigator, could affect seizure control.
• Epilepsy surgery planned during the study or epilepsy surgery within 6 months prior to Screening.
• Concomitant use of fenfluramine.
• Prior or concomitant use of lorcaserin.