Harmony Biosciences to Present Rare Epilepsy Data at the 36th International Epilepsy Congress

Harmony Biosciences Holdings, Inc. (Nasdaq: HRMY), today announced that it will present data from its rare epilepsy pipeline at the 36 th International Epilepsy Congress (IEC) being held August 30 September 3, 2025, at the Lisbon Congress Centre in Lisbon, Portugal.

Poster presentations will highlight information from the company's investigation of EPX-100 (clemizole hydrochloride) in two Phase 3 clinical studies (ARGUS and LIGHTHOUSE) for the treatment of Dravet syndrome and Lennox-Gastaut syndrome, respectively.

Both trials are currently enrolling and more information about the trials can be found at argustrial.com and lighthouselgsstudy.com .

The posters will be on display from Sunday, August 31 – Tuesday, September 2, from 1:45 pm -3:15 pm GMT. Poster presentation details are listed below:

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 DS patients. 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 a voltage-gated sodium channel gene, SCN1A1. 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 .

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Investor Contact:
Matthew Beck
astr partners
917-415-1750
matthew.beck@astrpartners.com

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