Harmony Biosciences Holdings Inc. has announced initial data from the open-label extension (OLE) of its ongoing Phase 3 ARGUS trial, which is evaluating EPX-100 (clemizole hydrochloride) for the treatment of Dravet syndrome. The data, to be presented at the 2025 American Epilepsy Society Annual Meeting in December, showed that participants with at least six months of exposure to EPX-100 experienced a median reduction of approximately 50% in countable motor seizure frequency per 28 days. Half of the participants achieved at least a 50% reduction in seizure frequency. EPX-100 was generally well-tolerated, with the most common adverse events being seizures, pyrexia, and upper respiratory tract infection. No significant gastrointestinal adverse events were reported. The ARGUS and LIGHTHOUSE trials for EPX-100 are ongoing, with topline data from ARGUS expected in 2026.