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Harmony Biosciences to Present Open-Label Extension Data From Phase 3 ARGUS Trial at the 2026 American Academy of Neurology Annual Meeting

Key Takeaway: Harmony Biosciences announced the presentation of open-label extension data from the Phase 3 ARGUS trial for EPX-100, targeting Dravet syndrome, at the 2026 American Academy of Neurology Annual Meeting. The trial is currently enrolling participants, and details about the trial can be found online. EPX-100 is an oral treatment aimed at modulating serotonin signaling in patients with Dravet syndrome.
Price reaction · baseline $29.42 (2026-04-16 close) · hit pre-market · clean, no other HRMY news in the window
day 0 close · peak
+1.9%

Market Sentiment Analysis

POSITIVE FACTORS

  • Presentation of new data from the Phase 3 ARGUS trial.
  • Focus on a rare neurological condition, Dravet syndrome.
  • Potential for innovative treatment with EPX-100.

BiopharmaWatch Analysis

From our catalyst data and publicly available data · not financial advice
Best trade, last catalyst
+43%
120-day peak, hindsight
Typical move
3.4%
average across 4 past catalysts
Lead asset
Clemizole
Phase 3 · Lennox Gastaut Syndrome

Full Press Release Details

PLYMOUTH MEETING, Pa.--(BUSINESS WIRE)--Harmony Biosciences Holdings, Inc. (Nasdaq: HRMY) today announced that it will present encore 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 2026 American Academy of Neurology Annual Meeting being held April 18 – 22 in Chicago, IL.
The ARGUS trial is currently enrolling, and more information about the trial can be found atargustrial.com.
Poster presentation details are listed below:
Abstract Title: ARGUS: A Study of EPX-100 (Clemizole Hydrochloride) as Adjunctive Therapy in Participants with Dravet Syndrome (DS): Preliminary Results from the Open-label Extension Phase
Poster #: P10.010
Date/Time: Wednesday, April 22, 2026, from 8:00 AM – 9:00 AM CT
About Clemizole Hydrochloride (EPX-100)EPX-100, clemizole hydrochloride, is under development for the treatment of Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS). EPX-100 acts by targeting central 5-hydroxytryptamine receptors to modulate serotonin signaling. The drug candidate is administered orally twice a day in a liquid formulation and has been developed based on a proprietary phenotype-based zebrafish drug screening platform. DS is caused by a loss of function mutation in theSCN1Agene, and scn1 mutant zebrafish replicate the genetic etiology and phenotype observed in the majority of individuals with DS. Thescn1Labmutant 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 SyndromeDravet syndrome (DS) is a severe and progressive epileptic encephalopathy that begins in infancy and 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 a risk of sudden unexpected death in epilepsy. Approximately 85% of Dravet syndrome cases are caused by de novo loss-of-function (LOF) mutations inSCN1Agene, which codes for a voltage-gated sodium channel. DS has an estimated incidence rate of 1:15,700.
About Harmony BiosciencesHarmony 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 visitwww.harmonybiosciences.com.

Frequently Asked Questions

What is the ARGUS trial?

The ARGUS trial is a Phase 3 study investigating EPX-100 for treating Dravet syndrome.

When will the data be presented?

The data will be presented at the 2026 American Academy of Neurology Annual Meeting.

What is EPX-100?

EPX-100, or clemizole hydrochloride, is an oral treatment targeting Dravet syndrome.

What is Dravet syndrome?

Dravet syndrome is a severe epilepsy disorder that begins in infancy and leads to high seizure frequency.

Last updated: Apr 17, 2026