A Study to Investigate LP352 in Children and Adults With Developmental and Epileptic Encephalopathies (DEE)

September 11, 2026 updated by: Longboard Pharmaceuticals

A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study to Investigate the Efficacy, Safety, and Tolerability of LP352 in the Treatment of Seizures in Children and Adults With Developmental and Epileptic Encephalopathies

This (DEEp OCEAN Study) is a double-blind, randomized, placebo-controlled, multicenter study to investigate the efficacy, safety, and tolerability of LP352 in the treatment of seizures in children and adults with DEE. The study consists of 3 main phases: Screening, Titration period, Maintenance period, followed by a Taper period and Follow-Up. The total duration of the study will be approximately 24 months.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

367

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Australia
    • New South Wales
      • Randwick, New South Wales, Australia, 2031
        • Sydney Children's Hospital - Randwick
      • Randwick, New South Wales, Australia, 2031
        • Prince of Wales Hospital (POWH)
      • Westmead, New South Wales, Australia, 2145
        • The Children's Hospital-Westmead - Heart Centre for Children
    • Queensland
      • Brisbane, Queensland, Australia, 4006
        • Royal Brisbane and Women's Hospital (RBWH)
      • Brisbane, Queensland, Australia, 4101
        • Queensland Children's Hospital (Lady Cilento Children's Hospital)
    • Victoria
      • Heidelberg, Victoria, Australia, 3084
        • Austin Hospital
      • Melbourne, Victoria, Australia, 3004
        • The Alfred Hospital
      • Parkville, Victoria, Australia, 3052
        • The Royal Children's Hospital (RCH) Melbourne
  • Belgium
    • Antwerp
      • Edegem, Antwerp, Belgium, 2650
        • Universitair Ziekenhuis Antwerpen (UZA)
    • Flemish Brabant
      • Leuven, Flemish Brabant, Belgium, 3000
        • Universitaire Ziekenhuizen Leuven - Campus Gasthuisberg
  • Brazil
      • São Paulo, Brazil, 05403-903
        • Universidade de Sao Paulo (USP) - Hospital das Clinicas da Faculdade de Medicina (HCFMUSP) - Inst...
    • Paraná
      • Curitiba, Paraná, Brazil, 81210-310
        • Instituto de Neurologia de Curitiba (INC)
    • Rio Grande do Sul
      • Porto Alegre, Rio Grande do Sul, Brazil, 90035-001
        • Moinhos de Vento Hospital (Hospital Moinhos de Vento) (HMV)
      • Porto Alegre, Rio Grande do Sul, Brazil, 90610-970
        • Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS) - Instituto Do Cerebro Do Rio Grand...
    • São Paulo
      • Campinas, São Paulo, Brazil, 13083-888
        • Universidade Estadual de Campinas (UNICAMP) - Hospital das Clinicas (HC)
      • Ribeirão Preto, São Paulo, Brazil, 14051-260
        • Universidade de Sao Paulo (USP)-Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto ...
      • São José do Rio Preto, São Paulo, Brazil, 15090-000
        • Faculdade de Medicina de Sao Jose do Rio Preto-SP (FAMERP)
  • Canada
    • British Columbia
      • Vancouver, British Columbia, Canada, V6H 3V4
        • BC Children's Hospital (British Columbia Children's Hospital)
    • Ontario
      • London, Ontario, Canada, N6A 5W9
        • London Health Sciences Centre (LHSC)
      • Toronto, Ontario, Canada, M5G 1X8
        • The Hospital for Sick Children (SickKids)
      • Toronto, Ontario, Canada, M5T 2S8
        • University Health Network-Toronto Western Hospital - Krembil Neuroscience Centre (KNC)
  • China
    • Beijing Municipality
      • Beijing, Beijing Municipality, China, 100034
        • Peking University First Hospital (Beida Hospital)
      • Beijing, Beijing Municipality, China, 100045
        • Capital Medical University-Beijing Children's Hospital
    • Guangdong
      • Guangzhou, Guangdong, China, 510260
        • Guangzhou Medical University-The Second Affiliated Hospital
      • Shenzhen Shi, Guangdong, China, 518026
        • Shenzhen Children's Hospital
    • Hubei
      • Wuhan, Hubei, China, 430016
        • Wuhan Children's Hospital
    • Shanghai Municipality
      • Shanghai Shi, Shanghai Municipality, China, 201102
        • Fudan University - Children's Hospital
  • France
      • Bron, France, 69500
        • Centre Hospitalier Universitaire de Lyon - Hôpital Pierre Wertheimer
      • Marseille, France, 13005
        • AP-HM- Hôpital de La Timone
      • Paris, France, 75019
        • AP-HP - Hôpital universitaire Robert-Debré
      • Paris, France, 75015
        • AP-HP - Hôpital universitaire Necker-Enfants malades
      • Strasbourg, France, 67098
        • Hôpital de Hautepierre - Les Hôpitaux Universitaires de Strasbourg
    • Nord
      • Lille, Nord, France, 59000
        • Hôpital Roger Salengro
    • Occitanie
      • Toulouse, Occitanie, France, 31059
        • Centre Hospitalier Universitaire (CHU) de Toulouse - Hopital de Psychiatrie
    • Île-de-France Region
      • Villejuif, Île-de-France Region, France, 94800
        • Chu de Rennes - Centre d'Evaluation et de Traitement de la Douleur de l'Adulte et de l'Enfant
  • Germany
      • Ravensburg, Germany, 88214
        • Epilepsie-Zentrum Bodensee
    • Hesse
      • Frankfurt am Main, Hesse, Germany, 60596
        • Universitätsklinikum Frankfurt - Klinikum der Goethe-Universität
    • North Rhine-Westphalia
      • Bielefeld, North Rhine-Westphalia, Germany, 33617
        • Gesellschaft fuer Epilepsieforschung e.V.
      • Bonn, North Rhine-Westphalia, Germany, 53127
        • Universitatsklinikum Bonn
    • Saxony
      • Radeberg, Saxony, Germany, 01454
        • Epilepsiezentrum Kleinwachau gemeinnützige GmbH
    • Schleswig-Holstein
      • Kiel, Schleswig-Holstein, Germany, 24105
        • Universitaetsklinikum Schleswig-Holstein (UKSH) - Campus Kiel - Klinik fuer Psychosomatik und Psy...
  • Italy
      • Genoa, Italy, 16147
        • Istituto Giannina Gaslini (Ospedale Pediatrico IRCCS) - Centro Malattie Rare
      • Milan, Italy, 20133
        • Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta
      • Pavia, Italy, 27100
        • Fondazione Mondino, IRCCS Istituto Neurologico Nazionale a Carattere Scientifico
      • Rome, Italy, 00165
        • Ospedale Pediatrico Bambino Gesu - Gianicolo
      • Rome, Italy, 00168
        • Universita Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A Gemelli - Centro pe...
      • Verona, Italy, 37126
        • Azienda Ospedaliera Universitaria Integrata Verona - Centro Fibrosi Cistica di Verona (CFC Verona)
    • Tuscany
      • Florence, Tuscany, Italy, 50139
        • Azienda Ospedaliero-Universitaria Meyer - Ospedale dei Bambini
  • Japan
      • Niigata, Japan, 950-2074
        • National Hospital Organization Nishi-Niigata Chuo National Hospital
      • Shizuoka, Japan, 420-0953
        • National Hospital Organization Shizuoka Institute of Epilepsy and Neurological Disorders
    • Chiba
      • Narita-shi, Chiba, Japan, 286-8520
        • International University of Health and Welfare - Narita Hospital
    • Fukuoka
      • Fukuoka, Fukuoka, Japan, 813-0017
        • Fukuoka Children's Hospital (FCH)
    • Hokkaido
      • Sapporo, Hokkaido, Japan, 060-8648
        • Hokkaido University Hospital
    • Okayama-ken
      • Okayama, Okayama-ken, Japan, 700-8558
        • Okayama University Hospital
    • Osaka
      • Osaka, Osaka, Japan, 534-0021
        • Osaka City General Hospital
    • Saitama
      • Saitama-shi, Saitama, Japan, 330-8777
        • Saitama Prefectural Children's Medical Center
    • Tochigi
      • Mibu-Machi, Tochigi, Japan, 321-0293
        • Dokkyo Medical University Hospital
    • Tokyo-To
      • Kodaira-shi, Tokyo-To, Japan, 187-8551
        • National Center of Neurology and Psychiatry-National Center Hospital
  • Latvia
      • Riga, Latvia, LV-1004
        • Bernu Kliniska Universitates Slimnica (BKUS) (University Children's Hospital)
  • Mexico
    • Mexico City
      • Mexico City, Mexico City, Mexico, 04530
        • Instituto Nacional de Pediatria (INP) (National Institute of Pediatrics)
  • Netherlands
      • Utrecht, Netherlands, 3584 CX
        • Universitair Medisch Centrum Utrecht - Polikliniek Oogheelkunde
  • Portugal
      • Coimbra, Portugal, 3000-602
        • Hospital Pediátrico de Coimbra
      • Lisbon, Portugal, 1649-035
        • Unidade Local de Saude Santa Maria, E.P.E (ULSSM)
      • Porto, Portugal, 4050
        • Centro Hospitalar Universitario de Santo Antonio - Centro Materno Infantil do Norte (CMIN)
  • Serbia
    • Beograd
      • Belgrade, Beograd, Serbia, 112112
        • University of Belgrade-Faculty of Medicine - Clinic of Neurology and Psychiatry for Children and ...
      • Belgrade, Beograd, Serbia, 11000
        • Univerzitetski Klinicki Centar Srbije - Klinika za Neurologiju
      • Belgrade, Beograd, Serbia, 11070
        • Institut za Zdravstvenu Zastitu Majke i Deteta Srbije Dr Vukan Cupic
    • Sumadijski Okrug
      • Kragujevac, Sumadijski Okrug, Serbia, 34000
        • Clinical Center Kragujevac
  • Spain
      • Barcelona, Spain, 08035
        • Hospital Universitari Vall d'Hebron
      • Barcelona, Spain, 8041
        • Hospital de la Santa Creu i Sant Pau
      • Madrid, Spain, 28034
        • Hospital Ruber Internacional
      • Madrid, Spain, 28010
        • Hospital Universitario Vithas Madrid La Milagrosa
      • Madrid, Spain, 28009
        • Hospital Infantil Universitario Nino Jesus (HIUNJS)
      • Málaga, Spain, 29010
        • Hospital Regional Universitario de Malaga - Hospital General
      • Málaga, Spain, 29016
        • Hospital Vithas Malaga
      • Valencia, Spain, 46026
        • Hospital Universitari i Politecnic La Fe de Valencia (Hospital La Fe Bulevar Sur)
    • Barcelona
      • Esplugues de Llobregat, Barcelona, Spain, 08950
        • Hospital Sant Joan de Deu Barcelona (HSJDB)
    • Navarre
      • Pamplona, Navarre, Spain, 31008
        • Hospital Universitario de Navarra
  • United Kingdom
      • London, United Kingdom, WC1N 3JH
        • Great Ormond Street Hospital for Children NHS Foundation Trust
      • London, United Kingdom, NW1 2PG
        • University College London Hospitals NHS Foundation Trust (UCLH)
    • East Wales
      • Cardiff, East Wales, United Kingdom, CF14 4XW
        • Cardiff and Vale University Health Board - University Hospital of Wales (UHW) - Noah's Ark Childr...
    • North East
      • Newcastle upon Tyne, North East, United Kingdom, NE1 4LP
        • The Newcastle upon Tyne Hospitals NHS Foundation Trust - Royal Victoria Infirmary (RVI)
    • South East
      • Southampton, South East, United Kingdom, SO16 6YD
        • University Hospital Southampton NHS Foundation Trust-Southampton General Hospital (SGH)
    • South Western Scotland
      • Glasgow, South Western Scotland, United Kingdom, G51 4TF
        • NHS Greater Glasgow and Clyde-Glasgow Clinical Research Facility - Queen Elizabeth University Hos...
    • West Midlands
      • Birmingham, West Midlands, United Kingdom, B15 2WB
        • University Hospitals Birmingham (UHB) NHS Foundation Trust - Queen Elizabeth Hospital Birmingham
  • United States
    • Arkansas
      • Little Rock, Arkansas, United States, 72202-3500
        • Arkansas Children's Hospital - Cardiology Clinic
    • California
      • Los Angeles, California, United States, 90095
        • University of California Los Angeles (UCLA) - David Geffen School of Medicine - Global Health Pro...
      • Los Angeles, California, United States, 90027-6062
        • Children's Hospital Los Angeles (CHLA)
      • Palo Alto, California, United States, 94304-1511
        • Stanford University - Stanford School of Medicine - Pulmonary and Cystic Fibrosis Center
      • San Francisco, California, United States, 94158
        • UCSF Benioff Children's Hospitals - San Francisco
    • Colorado
      • Aurora, Colorado, United States, 80045-7106
        • Children's Hospital Colorado - Heart Institute
    • District of Columbia
      • Washington D.C., District of Columbia, United States, 20010-2916
        • Children's National Hospital - Children's National Heart Center
    • Florida
      • Gulf Breeze, Florida, United States, 32561-4495
        • NW FL Clinical Research Group, LLC
      • Miami, Florida, United States, 33136-2117
        • University of Miami Medical Group (UMMG)
      • Miami, Florida, United States, 33155-3009
        • Nicklaus Children's Hospital (Miami Children's Hospital)
      • Orlando, Florida, United States, 32806
        • Research Institute of Orlando LLC
      • Tampa, Florida, United States, 33609-4191
        • Pediatric Epilepsy & Neurology Specialists (PENS)
      • Tampa, Florida, United States, 33620
        • University of South Florida (USF) - Tampa Campus
    • Georgia
      • Atlanta, Georgia, United States, 30329-2311
        • Children's Healthcare of Atlanta (CHOA)
      • Atlanta, Georgia, United States, 30329
        • Rare Disease Research, LLC. (RDR)
    • Idaho
      • Boise, Idaho, United States, 83702-5029
        • Consultants in Epilepsy & Neurology, PLLC
    • Illinois
      • Chicago, Illinois, United States, 60611-2908
        • Northwestern Memorial Hospital
      • Chicago, Illinois, United States, 60611-2991
        • Northwestern University - Ann & Robert H. Lurie Children's Hospital of Chicago - Center for Cance...
    • Iowa
      • Iowa City, Iowa, United States, 52242-1009
        • University of Iowa Health Care Medical Center (University of Iowa Hospitals & Clinics)
    • Maryland
      • Bethesda, Maryland, United States, 20817-1844
        • Mid-Atlantic Epilepsy and Sleep Center - Bethesda
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Massachusetts General Hospital (MGH)
    • Minnesota
      • Rochester, Minnesota, United States, 55905-0001
        • Mayo Clinic - Children's Center - Rochester
    • New Jersey
      • Livingston, New Jersey, United States, 07039-5817
        • Barnabas Health - Institute of Neurology and Neurosurgery
      • Morristown, New Jersey, United States, 07960-6092
        • Northeast Regional Epilepsy Group - Morristown
    • New York
      • New York, New York, United States, 10016-4852
        • NYU Langone Health-NYU Comprehensive Epilepsy Center
    • Oregon
      • Portland, Oregon, United States, 97239-3098
        • Oregon Health & Science University - Blood Brain Barrier and Neuro-Oncology Program
    • Tennessee
      • Memphis, Tennessee, United States, 38105-4625
        • Le Bonheur Children's Hospital - Outpatient Center
    • Texas
      • Austin, Texas, United States, 78731-3157
        • Child Neurology Consultants of Austin - Austin
      • Fort Worth, Texas, United States, 76104-2710
        • Cook Children's Jane and John Justin Neurosciences Center
      • Houston, Texas, United States, 77030-1517
        • The University of Texas Medical School at Houston - UT Gastroenterology
    • Washington
      • Tacoma, Washington, United States, 98415-0299
        • MultiCare Health System

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participants who are characterized as having Lennox-Gastaut Syndrome (LGS) must fulfill all of the following criteria:

    • Onset of seizures at ≤8 years old
    • History of tonic/tonic-atonic seizures plus at least 1 of the following seizure type(s): atypical absence, atonic, myoclonic, focal impaired awareness, generalized tonic-clonic, nonconvulsive status epilepticus, or epileptic spasms
    • Presence of developmental plateauing or regression
    • History of electroencephalogram (EEG) showing generalized slow (<2.5 Hertz [Hz]) spike-and-wave complexes

  • Participants who are characterized as having DEE (Other) must fulfill all of the following criteria:

    • Does not meet criteria for LGS
    • Onset of seizures at ≤5 years old
    • Presence of developmental plateauing or regression
    • History of multiple seizure types
    • History of interictal EEG background showing diffuse or multifocal slowing (with or without epileptiform activity)
  • The participant has a current occurrence of at least 1 of the following countable motor seizure types: generalized tonic-clonic, tonic (bilateral), clonic (bilateral), atonic (bilateral) with truncal/leg involvement, focal motor (including hemiclonic), and focal to bilateral tonic-clonic.
  • The participant has demonstrated an average of at least 4 countable motor seizures per month for each of the 3 months prior to Screening.
  • The participant has been taking 1 to 4 antiseizure medications (ASMs) at a stable dose for at least 4 weeks prior to Screening.
  • 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.
  • The participant must be willing and able to provide written informed consent; in instances where the participant is unable to provide consent, an appropriate legal representative.

Exclusion Criteria:

  • The participant has a diagnosis of Dravet Syndrome (DS) or has a mutation of the Sodium channel protein type 1 subunit alpha (SCN1A) gene consistent with DS.
  • The participant has been admitted to a medical facility for treatment of status epilepticus requiring mechanical ventilation within 3 months prior to Screening.
  • The participant has a neurodegenerative disorder as indicated by magnetic resonance imaging or genetic testing.
  • The participant has an acquired lesion/injury unrelated to the primary etiology that could contribute as a secondary cause of seizures.
  • The participant is receiving exclusionary medications.
  • The participant is currently using any cannabis product or cannabidiol that is not in oral solution/capsule/tablet form, not obtained from a government-approved dispensary, or contains ≥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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Placebo for LP352
Drug: Placebo
Participants will be administered with matching placebo orally or through G-tube/ PEG tube.
Other Names:
  • Placebo Comparator
Experimental: LP352
Participants will be titrated up to highest tolerated dose of LP352 during the Titration period (Visit 2 - Visit 5), followed by maintenance period (Visit 5 - Visit 8) and then taper/down titration period.
Drug: LP352
LP352 will be administered orally or through G-tube/ percutaneous endoscopic gastrostomy (PEG) tube
Other Names:
  • Bexicaserin

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Frequency Percent Change in Countable Motor Seizures During Treatment Compared to Baseline
Time Frame: Baseline and up to 15 Weeks
The percent change from Baseline in countable motor seizure frequency during Treatment will be calculated as countable motor seizure frequency during Treatment minus countable motor seizure frequency during Screening and divided by seizure frequency during Screening and multiplied by 100 where each seizure frequency will be based on number of seizures.
Baseline and up to 15 Weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Frequency Percent Change in Countable Motor Seizures during Maintenance compared to Baseline
Time Frame: Baseline and up to 15 Weeks
Baseline and up to 15 Weeks
Safety and Tolerability of LP352
Time Frame: Up to 21 Weeks
Safety and tolerability as measured by incidence and severity of Treatment Emergent Adverse Events (TEAEs), Serious Adverse events (SAEs), AEs leading to discontinuation and clinically significant changes in laboratory parameters (hematology, serum chemistry and Urinalysis), physical examination findings, vital signs, growth parameters (height and weight), 12-lead electrocardiograms (ECGs), Columbia-Suicide Severity Rating Scale (C-SSRS) responses, and Patient Health Questionnaire-9 (PHQ-9) total score and Question 9 score.
Up to 21 Weeks
Percentage of participants with ≥ 50% Reduction in countable motor seizures during the Treatment compared to Baseline
Time Frame: Baseline and up to 15 Weeks
Baseline and up to 15 Weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Longboard Pharmaceuticals

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 11, 2024

Primary Completion (Estimated)

October 31, 2026

Study Completion (Estimated)

November 30, 2026

Study Registration Dates

First Submitted

December 2, 2024

First Submitted That Met QC Criteria

December 2, 2024

First Posted (Actual)

December 5, 2024

Study Record Updates

Last Update Posted (Actual)

September 15, 2026

Last Update Submitted That Met QC Criteria

September 11, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • LP352-301
  • 2024-516412-17-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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