Harmony acquires Dravet syndrome treatment EPX-100 developer

Epygenix acquisition adds to Harmony's CNS assets

Andrea Lobo, PhD avatar

by Andrea Lobo, PhD |

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Epygenix Therapeutics, the company developing EPX-100 (clemizole) as a potential add-on treatment for people with Dravet syndrome, has been acquired by Harmony Biosciences.

“This acquisition builds on our leadership position in sleep/wake and our franchise in neurobehavioral disorders, allowing us to leverage our expertise in CNS [the central nervous system, or the brain and spinal cord] … to deliver new therapies to patients with unmet medical needs,” Jeffrey M. Dayno, MD, Harmony’s president and CEO, said in a company press release.

EPX-100’s safety and efficacy at controlling seizures in people with Dravet are being tested in a pivotal Phase 2 ARGUS trial (NCT04462770). The trial is enrolling people with Dravet, ages 2 and older, who have mutations in the SCN1A gene and experienced their first seizure when they were younger than 18 months.

Participants are being recruited at sites in the U.S., Canada, and several European countries, who are randomly assigned to receive either oral EPX-100 or a placebo for about five months. Topline data from the study is expected in 2026.

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“Harmony shares our team’s core values, including a commitment to patients and families living with Dravet syndrome … where a significant unmet need for effective therapies remains,” said Alex Yang, Epygenix’s chair and CEO.

Dravet syndrome is a type of epilepsy characterized by episodes of prolonged and severe seizures that are difficult to control with many existing medications for epilepsy, starting in the first year of life. The frequency of seizures may lead to cognitive and developmental issues.

In about 85% of patients, the disease is caused by mutations in the SCN1A gene, leading to the loss of function of a type of sodium channel found on the surface of nerve cells, involved in the transmission of nerve signals.

EPX-100 is a repurposed antihistamine, a type of medication used to relieve symptoms of allergies. In Dravet, the treatment is thought to suppress seizures by acting on serotonin signaling pathways, thought to be altered in people with Dravet. Serotonin is a brain chemical messenger.

The treatment was found to reduce seizures in a study that tested more than 3,000 approved medications in zebrafish models of Dravet syndrome. A Phase 1 trial (NCT04069689) revealed EPX-100 was safe and well tolerated in healthy volunteers, and its pharmacological properties were consistent with animal studies and proportional to the treatment dosing.

The ongoing Phase 2 trial begins with a four-week observational period to establish each participant’s seizure frequency, followed by four weeks to determine the highest tolerated dose and 12 weeks at a maintenance dose. The main goal is to assess changes in seizure frequency after completing the treatment, compared with the observational period.

Secondary goals include changes in the number of seizure-free days, seizure severity, sleep disturbances, and patients’ quality of life. After completing the trial, patients may enter a three-year, open-label extension phase.

EPX-100 is also poised to enter a Phase 3 trial in people with Lennox-Gastaut syndrome, a condition similar to Dravet.

“Harmony’s demonstrated expertise in drug development and commercialization will accelerate the full potential of these treatments and make a real difference in the lives of Dravet and Lennox-Gastaut families,” Yang said.

The U.S. Food and Drug Administration (FDA) designated EPX-100 an orphan drug in 2017, meaning the medication was eligible for a range of incentives meant to accelerate the development of new therapies for rare diseases. In 2019, the agency granted the treatment investigational new drug status for Dravet syndrome, allowing it to enter human clinical trials.