An open-label extension is a continuation of a clinical trial where all participants and researchers know which treatment is being given, often after an initial blinded phase. It allows further study of a drug's long-term safety and effectiveness. For investors, it can indicate ongoing interest and confidence in a product's potential, influencing perceptions of its future value.
Phase 3medical
Phase 3 is the late-stage clinical testing step for a new drug or medical treatment, where the product is given to large groups of patients to confirm effectiveness, monitor side effects, and compare it to standard care. Successful Phase 3 results are often the final scientific hurdle before regulators decide on approval and market launch—like passing a final exam before graduation—and can sharply change a company's valuation and future revenue prospects.
Dravet syndromemedical
A rare, severe form of epilepsy that begins in infancy and causes frequent, prolonged seizures, developmental delays, and heightened risk of sudden unexplained death. It is caused by genetic changes that disrupt normal brain electrical activity—like a faulty circuit that repeatedly trips—so standard treatments often work poorly. Investors pay attention because the high unmet need, clear genetic target, and regulatory incentives can make therapies for this condition commercially and clinically significant, but trials are often long and costly.
adjunctive therapymedical
Adjunctive therapy is a treatment given in addition to a primary therapy to boost its effectiveness, reduce side effects, or treat related symptoms — like adding a side dish to make a main meal work better. For investors, evidence that an adjunctive therapy improves outcomes, safety, or convenience can expand a product’s use, support stronger regulatory labeling and reimbursement, and increase commercial potential by reaching more patients or strengthening a therapy’s market position.
drug-drug interactionmedical
When one medication changes how another medication works or how the body handles it, that is a drug-drug interaction; it can make a drug stronger, weaker, or produce unexpected side effects—think of mixing two recipes and getting a very different dish. Investors pay attention because interactions can alter a drug’s safety profile, limit who can use it, trigger label warnings or additional testing, and therefore affect sales, market access, and regulatory risk.
CYP enzymesmedical
CYP enzymes are a family of liver proteins (commonly called cytochrome P450) that act like the body’s chemical recycling machines, breaking down drugs and other foreign compounds so they can be cleared. Investors care because how quickly or slowly a drug is processed affects dose, side effects, approval risk and whether it will interact dangerously with other medicines—factors that influence a drug’s safety profile, labeling, marketability and revenue potential.
PLYMOUTH MEETING, Pa.--(BUSINESS WIRE)--
Harmony Biosciences Holdings, Inc. (Nasdaq: HRMY), today announced that it will highlight new open-label extension data from the company’s investigation of EPX-100 (clemizole hydrochloride) in the ongoing Phase 3 ARGUS trial for the treatment of Dravet syndrome at the 2025 American Epilepsy Society (AES) Annual Meeting being held December 5 – December 9, 2025, in Atlanta, GA.
The ARGUS trial is currently enrolling, and more information can be found at argustrial.com.
The posters will be on display on Monday, December 8, from 8:00 am - 2:00 pm ET. Poster presentation details are listed below:
Abstract Title:
EPX-100 as Adjunctive Therapy in Patients With Dravet Syndrome: Preliminary Results From the Open-Label Extension Phase of the ARGUS Study
Poster #:
3.353
Presentation:
Monday, December 8, from 12:00 pm – 1:45 pm ET
Abstract Title:
A Drug-Drug Interaction Study of EPX-100 (Clemizole Hydrochloride) With Clinical Probe Substrates for Selected CYP Enzymes
Poster #:
3.359
Presentation:
Monday, December 8, from 12:00 pm – 1:45 pm ET
About Clemizole Hydrochloride (EPX-100)
EPX-100, clemizole hydrochloride, is an investigational product under development for the treatment of Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS). EPX-100 acts by targeting central 5-hydroxytryptamine 2 (5HT-2) receptors to modulate serotonin signaling. EPX-100 is administered orally twice a day in a liquid formulation and has been developed based on a proprietary phenotype-based zebrafish drug screening platform. These scn1Lab mutant zebrafish replicate the genetic etiology and phenotype observed in the majority of individuals with DS. The scn1Lab mutant zebrafish model that expresses voltage gated sodium channels has been used for high-throughput screening of compounds that modulate Nav1.1 in the central nervous system.
About Dravet Syndrome
Dravet syndrome (DS) is a severe and progressive developmental epileptic encephalopathy that causes significant impact on patient functioning. DS 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 (SUDEP). Approximately 85% of Dravet syndrome cases are caused by de novo loss-of-function (LOF) mutations in a voltage-gated sodium channel gene, SCN1A. DS has an estimated incidence rate of 1:15,700 in the US.
About Harmony Biosciences
Harmony Biosciences is a pharmaceutical company dedicated to developing and commercializing innovative therapies for patients with rare neurological diseases who have unmet medical needs. Driven by novel science, visionary thinking, and a commitment to those who feel overlooked, Harmony Biosciences is nurturing a future full of therapeutic possibilities that may enable patients with rare neurological diseases to truly thrive. Established by Paragon Biosciences, LLC, in 2017 and headquartered in Plymouth Meeting, Pa., we believe that when empathy and innovation meet, a better future can begin; a vision evident in the therapeutic innovations we advance, the culture we cultivate, and the community programs we foster. For more information, please visit www.harmonybiosciences.com.
