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Investigating LP352 for treating seizures in children and adults with developmental and epileptic encephalopathy

A Phase 3, Open-Label Study to Investigate the Long-Term Safety and Efficacy of LP352 in the Treatment of Seizures in Children and Adults With Developmental and Epileptic Encephalopathy

PHASE3 · Longboard Pharmaceuticals · NCT06908226

This study is testing a new medication called LP352 to see if it can help control seizures and improve the well-being of children and adults with developmental and epileptic encephalopathy who have already been part of earlier studies.

Quick facts

PhasePHASE3
Study typeInterventional
Enrollment324 (estimated)
Ages2 Years to 66 Years
SexAll
SponsorLongboard Pharmaceuticals (industry)
Locations33 sites (Little Rock, Arkansas and 32 other locations)
Trial IDNCT06908226 on ClinicalTrials.gov

What this trial studies

This multicenter, open-label study aims to evaluate the long-term safety, efficacy, tolerability, and pharmacokinetics of LP352 in patients with developmental and epileptic encephalopathy (DEE) who have previously participated in studies LP352-301 or LP352-302. The study includes several phases: Screening, Titration, Maintenance, Taper, and Follow-Up, spanning approximately 14 months. Participants will be monitored for their response to LP352, focusing on seizure control and overall well-being.

Who should consider this trial

Good fit: Ideal candidates are children and adults with a diagnosis of DEE, including Dravet Syndrome or Lennox-Gastaut Syndrome, who have completed prior LP352 studies.

Not a fit: Patients currently using exclusionary medications or certain cannabis products may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide a new treatment option for managing seizures in patients with DEE.

How similar studies have performed: Other studies have explored treatments for DEE, but the specific approach with LP352 is novel and has not been extensively tested.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* The participant has satisfactorily completed Study LP352-301 or LP352-302 Visit 8, and who, in the opinion of the investigator, may benefit from continued LP352 administration.
* Diagnosis of DEE that includes Dravet Syndrome (DS), Lennox-Gastaut Syndrome (LGS), or DEE Other (as defined and evaluated in Study LP352-301 or LP352-302).
* Has at least one reliable and consistent parent, legal guardian, or caregiver during the study.
* The participant or legal representative must be willing and able to provide written informed consent
* The participant, parent, or caregiver is willing and able (in the judgment of the investigator) to comply with completion of the diaries throughout the study.

Exclusion Criteria:

* The participant is receiving exclusionary medications.
* Current use of any cannabis product or cannabidiol that is not in oral solution/capsule/tablet form, not obtained from a government-approved dispensary, or containing ≥50% Delta-9-tetrahydrocannabinol (THC).
* The participant has unstable, clinically significant neurologic (other than the disease being studied, eg, recurrent strokes), psychiatric, cardiovascular (eg, pulmonary arterial hypertension, cardiac valvulopathy, orthostatic hypotension/tachycardia) pulmonary, hepatic, renal, metabolic, gastrointestinal, urologic, immunologic, hematopoietic, or endocrine disease or other abnormality which may impact the ability of the participant to participate or potentially confound the study results.
* The participant is unable or unwilling to comply with any of the study requirements or timelines.

Where this trial is running

Little Rock, Arkansas and 32 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Developmental and Epileptic Encephalopathy, LP352, Bexicaserin, Seizures, DEEp OLE, Antiseizure medications, Epilepsy, Neurodevelopmental disorders

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.