EPX-100 for Lennox-Gastaut syndrome
Fact-checked by What is EPX-100 for Lennox-Gastaut syndrome?
EPX-100 (clemizole hydrochloride) is an experimental oral therapy being developed by Harmony Biosciences for the treatment of Lennox-Gastaut syndrome (LGS).
The main ingredient in EPX-100 is clemizole hydrochloride, an antihistamine medication used decades ago for treating allergies. It aims to control seizures in LGS by modulating activity at receptors that respond to the brain signaling chemical serotonin. This is expected to help control the abnormal nerve cell signaling that causes seizures.
Harmony is also developing EPX-100 for the treatment of Dravet syndrome, another severe form of pediatric epilepsy. In the U.S., the medication has been granted orphan drug designation and rare pediatric disease designation for the treatment of LGS and Dravet. These statuses aim to facilitate the clinical development of the treatment.
EPX-100 is in Phase 3 testing for LGS. If the trial data are positive, Harmony anticipates a decision on regulatory approval in 2028.
Therapy snapshot
| Treatment name | EPX-100 |
| Administration | Oral liquid |
| Clinical testing | Currently in Phase 3 testing |
How will EPX-100 be administered in LGS?
In an LGS clinical trial, EPX-100 is administered as an oral liquid, taken twice daily. The exact dose being tested has not been published.
EPX-100 in Lennox-Gastaut syndrome clinical trials
The Phase 3 LIGHTHOUSE study (NCT05066217) is evaluating the safety and efficacy of EPX-100 as an add-on to standard medications in around 260 people with LGS, ages 2 to 55.
Participants will receive either EPX-100 or a placebo for about four months, after which all participants can receive EPX-100 in an open-label extension period for up to three years.
The main goal is to evaluate changes in the monthly frequency of major motor seizures in the first four months. Other measures of seizure frequency, as well as caregiver- and clinician-reported impressions of clinical change, will also be evaluated. Topline data are expected in the first half of 2027.
No previous trials tested the therapy in people with LGS, however, the treatment was found to reduce seizure frequency in people with Dravet syndrome in a Phase 3 trial.
EPX-100 side effects
As clinical testing is ongoing, the side effect profile of EPX-100 in people with LGS is not yet known.
In a Dravet syndrome clinical trial, common treatment-emergent adverse events included breakthrough seizures, fever, and upper respiratory tract infection.
Lennox-Gastaut Syndrome News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
