Harmony Biosciences to Present Phase 3 EPX-100 Data for Dravet Syndrome at AES Annual Meeting
Key Insights
Harmony Biosciences will present new open-label extension data from its ongoing Phase 3 ARGUS trial evaluating EPX-100 for Dravet syndrome (search) at the American Epilepsy (search) Society Annual Meeting on December 8, 2025.
EPX-100 (clemizole hydrochloride) targets central 5-hydroxytryptamine 2 receptors (search) to modulate serotonin signaling and is administered orally twice daily in liquid formulation for this rare, severe epilepsy (search) condition.
The ARGUS trial includes a 4-week observational period, 16-week double-blind period, and open-label extension for up to 156 weeks, with topline data expected in 2026.
Harmony Biosciences Holdings Inc. (NASDAQ: HRMY) will present new open-label extension data from its ongoing Phase 3 ARGUS trial evaluating EPX-100 for Dravet syndrome (search) at the American Epilepsy (search) Society Annual Meeting on December 8, 2025, in Atlanta, Georgia. The company expects to report topline data from the phase 3 ARGUS trial in 2026.
Phase 3 ARGUS Trial Design
The ARGUS trial is evaluating the efficacy and safety of EPX-100 (clemizole hydrochloride) as an adjunctive therapy in children and adult participants with Dravet syndrome (search). The study design includes a 4-week Observational Period, a 16-week Double-Blind Period, and an Open-Label Extension Period for up to 156 weeks. The trial is currently enrolling participants.
Poster presentations will be displayed on Monday, December 8, from 8:00 am to 2:00 pm ET during the conference.
EPX-100 Mechanism and Development
EPX-100, clemizole hydrochloride, is an investigational oral therapy that acts by targeting central 5-hydroxytryptamine 2 (5HT-2) receptors to modulate serotonin signaling. The drug is administered orally twice a day in a liquid formulation and has been developed based on a proprietary phenotype-based zebrafish drug screening platform.
The development utilized scn1Lab mutant zebrafish that replicate the genetic etiology and phenotype observed in the majority of individuals with Dravet syndrome (search). This scn1Lab mutant zebrafish model expresses voltage gated sodium channels and has been used for high-throughput screening of compounds that modulate Nav1.1 (search) in the central nervous system.
EPX-100 originally developed by Epygenix Therapeutics (search) became part of Harmony Biosciences' pipeline when the company acquired Epygenix in April 2024. The investigational product is under development for both Dravet syndrome (search) and Lennox-Gastaut syndrome (search).
Dravet Syndrome Disease Burden
Dravet syndrome (search) is a severe and progressive developmental epileptic encephalopathy that causes significant impact on patient functioning. The condition begins in the first year of life and is characterized by high seizure frequency and severity, intellectual disability, and an increased risk of sudden unexpected death in epilepsy (search) (SUDEP).
Approximately 85% of Dravet syndrome (search) cases are caused by de novo loss-of-function mutations in a voltage-gated sodium channel gene, SCN1A (search). The estimated incidence rate of Dravet syndrome is 1:15,700 in the United States.
Company Performance
Harmony Biosciences stock has traded in a range of $25.52 to $40.93 over the past year, closing Tuesday's trading at $36.01, up 1.41%. The Plymouth Meeting, Pennsylvania-based pharmaceutical company focuses on developing and commercializing innovative therapies for patients with rare neurological diseases who have unmet medical needs.