Harmony Biosciences Announces Poster Presentations at the 16th European Epilepsy Congress

Harmony Biosciences will present new EPX-100 epilepsy data, including ARGUS extension results and drug-interaction findings, at the European Epilepsy Congress.

Rhea-AI Summary

Harmony Biosciences (HRMY) will present encore data on its investigational therapy EPX-100 (clemizole hydrochloride) at the 16th European Epilepsy Congress in Athens, Greece, held from September 5-9, 2026.

The company will share preliminary results from the open-label extension phase of the ARGUS study evaluating EPX-100 as adjunctive therapy in Dravet syndrome, and data from a drug-drug interaction study of EPX-100 with clinical probe substrates for selected CYP enzymes. Both posters (P0342 and P0331) are scheduled for September 6, from 2:00-3:00 pm EEST. EPX-100 is an orally administered liquid formulation in development for Dravet syndrome and Lennox-Gastaut syndrome, targeting central 5-hydroxytryptamine receptors to modulate serotonin signaling, and was identified using a phenotype-based zebrafish screening platform.

News Explained

The new lifecycle information is that both the ongoing ARGUS and LIGHTHOUSE trials are currently enrolling; EPX-100 therefore remains an investigational program, with the announced posters still representing future disclosures rather than completed clinical milestones.

Market Context

The August 27 conference announcement was followed by a 0.53% HRMY move. That record places this pre...

Analysis

The August 27 conference announcement was followed by a 0.53% HRMY move. That record places this presentation notice within a history of modest event responses; investors could watch the September posters and subsequent trial updates.

Key Figures

Congress edition: 16th Congress dates: September 5-9 ARGUS poster: P0342 +5 more

8 metrics

Congress edition 16th European Epilepsy Congress

Congress dates September 5-9 Athens, Greece

ARGUS poster P0342 September 6, 2:00-3:00 pm EEST

Drug-drug interaction poster P0331 September 6, 2:00-3:00 pm EEST

Cases caused by SCN1A mutations Approximately 85% Dravet syndrome cases

Dravet syndrome incidence 1:15,700 Estimated incidence rate

LGS onset age 3-5 years Typical age of onset

U.S. LGS patients Approximately 48,000 patients Lennox-Gastaut syndrome

Historical Context

5 past events · Latest: Aug 27 (Neutral)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Aug 27	Conference participation	Neutral	+0.5%	Management scheduled a fireside chat at the Cantor Global Healthcare Conference.
Aug 06	Symposium participation	Neutral	+1.3%	Management scheduled a fireside chat at the Piper Sandler CNS Symposium.
Aug 04	Earnings and clinical data	Positive	+8.9%	Record Q2 revenue accompanied initial BP-205 Phase 1 clinical data.
Jul 21	Earnings date notice	Neutral	+10.0%	The company scheduled its second-quarter 2026 results release and conference call.
Jul 16	Leadership change	Negative	-3.9%	The CFO stepped down and an interim principal financial officer was appointed.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

HRMY rose after recent conference and earnings-date notices, while it fell after the CFO transition; reactions varied by catalyst.

Key Terms

open-label extension phase, cyp enzymes, 5-hydroxytryptamine receptors, voltage gated sodium channels

4 terms

open-label extension phase medical

"Preliminary Results From the Open-Label Extension Phase of the ARGUS Study"

An open-label extension phase is a stage that follows a blinded clinical trial in which both participants and researchers know which treatment is being given. It lets people who completed the earlier trial continue receiving the study drug so investigators can collect longer-term safety and effectiveness data, like watching how a new tool performs over months instead of weeks. Investors care because these results can change the evidence available for regulatory decisions, labeling, and market confidence by revealing longer-term benefits or risks.

cyp enzymes medical

"With Clinical Probe Substrates for Selected CYP Enzymes"

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.

5-hydroxytryptamine receptors medical

"EPX-100 acts by targeting central 5-hydroxytryptamine receptors"

Proteins on the surface of nerve and other cells that bind the neurotransmitter serotonin (5-hydroxytryptamine) and trigger different biological responses; there are multiple subtypes (e.g., 5-HT1, 5-HT2, 5-HT3) with distinct actions in the brain, gut, and cardiovascular system. They matter to investors because these receptors are common drug targets for conditions such as depression, anxiety, migraine and gastrointestinal disorders, so discoveries, clinical results or regulatory changes around them can affect a drug’s commercial prospects—think of receptors as locks and drugs as keys.

voltage gated sodium channels medical

"model that expresses voltage gated sodium channels"

Proteins in cell membranes that open or close in response to changes in electrical voltage, allowing sodium ions to flow into nerve, muscle, and heart cells and thereby starting and carrying electrical signals like nerve impulses and heartbeats. They matter to investors because they are common drug and diagnostic targets and are implicated in many disorders; changes in a therapy’s effect on these channels can shape clinical trial outcomes, regulatory review, safety profiles, and market potential — think of them as gated doors that let electrical charge into cells to trigger signals.

AI-generated analysis. How Rhea-AI works. Not financial advice.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

PLYMOUTH MEETING, Pa., Sept. 03, 2026 (GLOBE NEWSWIRE) -- Harmony Biosciences Holdings, Inc. (Nasdaq: HRMY) today announced that it will present encore data from the company’s investigation of EPX-100 (clemizole hydrochloride) at the 16^th European Epilepsy Congress being held from September 5-9, in Athens, Greece.

The company is investigating EPX-100 for the treatment of Dravet syndrome and Lennox-Gastaut syndrome in the ongoing ARGUS and LIGHTHOUSE trials, respectively. These trials are currently enrolling, and more information can be found at argustrial.com and lighthouselgsstudy.com.

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 #:		P0342
Date/Time:		September 6, from 2:00-3:00 pm EEST

Abstract Title:		A Drug-Drug Interaction Study of EPX-100 (Clemizole Hydrochloride) With Clinical Probe Substrates for Selected CYP Enzymes
Poster #:		P0331
Date/Time:		September 6, from 2:00-3:00 pm EEST

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 the SCN1A gene, and scn1 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 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 in SCN1A gene, which codes for a voltage-gated sodium channel. DS has an estimated incidence rate of 1:15,700.

About Lennox-Gastaut Syndrome
Lennox-Gastaut syndrome (LGS) is a rare and drug-resistant epileptic encephalopathy characterized by onset in children between 3-5 years of age. The underlying cause of LGS is unknown and can be related to a wide range of factors including genetic differences and structural differences in the brain. As a result, patients experience multiple seizure types, including atonic seizures, and developmental, cognitive, and behavioral issues. LGS affects approximately 48,000 patients in the U.S.

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.

Harmony Biosciences Investor Contact:
Brennan Doyle
484-566-3685
bdoyle@harmonybiosciences.com

Harmony Biosciences Media Contact:
Cate McCanless
202-641-6086
cmccanless@harmonybiosciences.com

FAQ

What did Harmony Biosciences (HRMY) announce about EPX-100 at the 16th European Epilepsy Congress?

Harmony Biosciences announced it will present encore data on EPX-100 (clemizole hydrochloride) at the 16th European Epilepsy Congress in Athens, Greece. The presentations include preliminary open-label extension results from the ARGUS Dravet syndrome study and a drug-drug interaction study with selected CYP enzyme substrates.

When will Harmony Biosciences present its EPX-100 posters at the European Epilepsy Congress 2026?

Harmony Biosciences is scheduled to present two EPX-100 posters on September 6, from 2:00-3:00 pm EEST. Poster P0342 covers the ARGUS open-label extension in Dravet syndrome, and poster P0331 reports on a drug-drug interaction study with selected CYP enzymes.

What is EPX-100 being developed for by Harmony Biosciences (HRMY)?

EPX-100, or clemizole hydrochloride, is under development for the treatment of Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS). It is an orally administered liquid formulation that targets central 5-hydroxytryptamine receptors to modulate serotonin signaling in rare, severe epileptic encephalopathies.

What clinical studies of EPX-100 are mentioned by Harmony Biosciences (HRMY)?

The announcement highlights two ongoing trials: the ARGUS study, investigating EPX-100 as adjunctive therapy for Dravet syndrome, and the LIGHTHOUSE study in Lennox-Gastaut syndrome. Both trials are currently enrolling patients, with further information available at argustrial.com and lighthouselgsstudy.com.

How does EPX-100 work and how was it discovered?

EPX-100 acts by targeting central 5-hydroxytryptamine (serotonin) receptors to modulate serotonin signaling and is given orally twice daily as a liquid. It was developed using a proprietary phenotype-based zebrafish drug screening platform, including an scn1 mutant zebrafish model that reflects the genetics and phenotype of Dravet syndrome.