Developmental and Epileptic EncephalopathyPhase 3NCT06908226
A Study to Investigate LP352 in Children and Adults With Developmental and Epileptic Encephalopathy (DEE)
A Phase 3 study testing LP352 in people with Developmental and Epileptic Encephalopathy, run by Longboard Pharmaceuticals at 88 sites in 17 countries.
Trial summary
This (DEEp OLE Study) is a multicentre, open-label study to investigate the long-term safety, efficacy, tolerability, and pharmacokinetics (PK) of LP352 in the treatment of seizures in children and adults with DEE who completed Study LP352-301 or LP352-302. Read more about this study
- Who is it for?
- Ages 2 to 66 years
- Conditions the study is for
- Developmental and Epileptic Encephalopathy
- What is being tested?
- LP352
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 324 participants
- Where
- 88 sitesin 17 countries
- Study dates
- 12 Feb 2025to 17 Dec 2027
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 2 to 66 years
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- 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).
- Participant has a body weight of ≥10 kg.
- G-tubes/PEG tubes (if applicable) should be in stable and good working condition. Nasogastric tubes are not allowed except for short-term management.
- Has at least one reliable and consistent parent, legal guardian, or caregiver during 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 LAR must provide informed consent and the participant will need to assent (as per local regulations) before participation in the study. If the participant cannot provide consent or assent (ie, due to developmental status), the investigator should document why it was not obtained.
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- The participant and/or authorized representative is willing to provide written consent or assent to allow the investigator and the investigator's staff to consult with the participant's medical caregivers and the medical monitor during Screening and during participation in the study.
- All participants of childbearing potential must have a negative urine or serum pregnancy (human chorionic gonadotropin) test at Visit 8 from Study LP352-301 or LP352-302 and agrees to routinely use an acceptable effective method of contraception from the time of signing informed consent up to 48 hours after the last dose of study drug.
- Participant and/or participant's caregiver(s) agree to not post any participant's personal medical data related to the study or information related to the study on any website or social media site until the study has been completed.
- 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.
Who cannot join
- The participant is receiving exclusionary medications.
- Considered at risk of suicidal behavior based on the C-SSRS at Visit 8 of LP352-301 or LP352-302. If the participant is unable to complete the C-SSRS due to developmental status, the participant's LAR may not complete the C-SSRS. In these cases, the investigator may use clinical judgment to assess both the participant's status regarding suicidality and the ability to complete the scale, both of which must then be documented in the source document.
- Has a PHQ-9 score of >9 or a positive response to Question 9 at Visit 8 of LP352-301 or LP352-302. If the participant is unable to complete the PHQ-9, the participant's LAR may not complete the PHQ-9. In these cases, the investigator may use clinical judgment to assess both the participant's status and ability to complete the scale, both of which must then be documented in the source document.
- Ongoing AE from LP352-301 or LP352-302 of severe depression, anorexia nervosa, or bulimia per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.
- Has an abnormal and clinically significant 12-lead ECG at Visit 8 in LP352-301 or LP352-302 in the opinion of the investigator, for example, second- or third-degree heart block or a QTc of >450 msec for adult males, >470 msec for adult females, or >440 msec for pediatric participants.
- Ongoing AE in LP352-301 or LP352-302 of alcohol, opioid, or other drug use disorder, as per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.
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- 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% THC. Cannabis product or cannabidiol should be used primarily to treat seizures and dose should not be adjusted for the duration of the study. Cannabis product or cannabidiol will count as a concurrent ASM.
- Has a positive result on the urine drug screen at Visit 8 of LP352-301 or LP352-302, except for positive results related to prescribed controlled medications (eg, benzodiazepine) or Epidiolex®/government-approved cannabis product/cannabidiol used to treat seizures (eg, tetrahydrocannabinol).
- 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 (severe hepatic impairment), renal (severe renal impairment), metabolic, gastrointestinal, urologic, immunologic, hematopoietic, or endocrine disease or other abnormality at Visit 8 of LP352-301 or LP352-302 which may impact the ability of the participant to participate or potentially confound the study results.
- Is pregnant, breast-feeding, or intending to become pregnant during or within 48 hours after the last dose of study drug; or intending to donate ova during such time period.
- Has a known hypersensitivity to any component of LP352 formulation or any history of serious drug-induced hypersensitivity, eg, toxic epidermal necrolysis or Drug Reaction with Eosinophilia and Systemic Symptoms.
- Unwilling to abstain from donation of blood during and within 2 weeks after the study.
- Is unable or unwilling to comply with any of the study requirements or timelines.
Trial locations and contacts
88 sites in 17 countries. Contact the study team or a site near you to ask about taking part.
88 sites in 17 countries
United States21 sites
Children's Hospital Colorado - Heart Institute
Aurora, Colorado, 80045-7106
Child Neurology Consultants of Austin - Austin
Austin, Texas, 78731-3157
Mid-Atlantic Epilepsy and Sleep Center - Bethesda
Bethesda, Maryland, 20817-1844
Consultants in Epilepsy & Neurology, PLLC
Boise, Idaho, 83702-5029
Massachusetts General Hospital (MGH)
Boston, Massachusetts, 02114
NW FL Clinical Research Group, LLC
Gulf Breeze, Florida, 32561-4495
The University of Texas Medical School at Houston - UT Gastroenterology
Houston, Texas, 77030-1517
University of Iowa Health Care Medical Center (University of Iowa Hospitals & Clinics)
Iowa City, Iowa, 52242-1009
Arkansas Children's Hospital - Cardiology Clinic
Little Rock, Arkansas, 72202-3500
Barnabas Health - Institute of Neurology and Neurosurgery
Livingston, New Jersey, 07039-5817
University of California Los Angeles (UCLA) - David Geffen School of Medicine - Global Health Pro...
Los Angeles, California, 90095
University of Miami Medical Group (UMMG)
Miami, Florida, 33136-2117
Northeast Regional Epilepsy Group - Morristown
Morristown, New Jersey, 07960-6092
NYU Langone Health-NYU Comprehensive Epilepsy Center
New York, New York, 10016-4852
Research Institute of Orlando LLC
Orlando, Florida, 32806
Stanford University - Stanford School of Medicine - Pulmonary and Cystic Fibrosis Center
Palo Alto, California, 94304-1511
Oregon Health & Science University - Blood Brain Barrier and Neuro-Oncology Program
Portland, Oregon, 97239-3098
Mayo Clinic - Children's Center - Rochester
Rochester, Minnesota, 55905-0001
UCSF Benioff Children's Hospitals - San Francisco
San Francisco, California, 94158
Pediatric Epilepsy & Neurology Specialists (PENS)
Tampa, Florida, 33609-4191
University of South Florida (USF) - Tampa Campus
Tampa, Florida, 33620
Spain9 sites
Hospital Universitari Vall d'Hebron
Barcelona, 08035
Hospital de la Santa Creu I Sant Pau
Barcelona, 8041
Hospital Sant Joan de Deu Barcelona (HSJDB)
Esplugues de Llobregat, Barcelona, 08950
Hospital Infantil Universitario Nino Jesus (HIUNJS)
Madrid, 28009
Hospital Universitario Vithas Madrid La Milagrosa
Madrid, 28010
Hospital Ruber Internacional
Madrid, 28034
Hospital Regional Universitario de Malaga - Hospital General
Málaga, 29010
Hospital Universitario de Navarra
Pamplona, Navarre, 31008
Hospital Universitari i Politecnic La Fe de Valencia (Hospital La Fe Bulevar Sur)
Valencia, 46026
Japan8 sites
National Center of Neurology and Psychiatry-National Center Hospital
Kodaira-shi, Tokyo-To, 187-8551
Dokkyo Medical University Hospital
Mibu-Machi, Tochigi, 321-0293
International University of Health and Welfare - Narita Hospital
Narita-shi, Chiba, 286-8520
National Hospital Organization Nishi-Niigata Chuo National Hospital
Niigata, 950-2074
Okayama University Hospital
Okayama, Okayama-ken, 700-8558
Osaka City General Hospital
Osaka, Osaka, 534-0021
Saitama Prefectural Children's Medical Center
Saitama-shi, Saitama, 330-8777
National Hospital Organization Shizuoka Institute of Epilepsy and Neurological Disorders
Shizuoka, 420-0953
France7 sites
Hospices Civils de Lyon (HCL) - Hopital Pierre Wertheimer
Bron, Auvergne-Rhône-Alpes, 69500
Hôpital Roger Salengro
Lille, Nord, 59000
AP-HM- Hôpital de La Timone
Marseille, 13005
AP-HP - Hôpital universitaire Necker-Enfants malades
Paris, 75015
AP-HP - Hôpital universitaire Robert-Debré
Paris, 75019
Les Hôpitaux Universitaires de Strasbourg - Hôpital de Hautepierre
Strasbourg, Ain, 67098
CHU de Toulouse - Hôpital Pierre-Paul Riquet
Toulouse, 31059
Italy7 sites
Azienda Ospedaliero-Universitaria - Ospedale Pediatrico Meyer
Florence, Florence, 50139
Istituto Giannina Gaslini (Ospedale Pediatrico IRCCS) - Centro Malattie Rare
Genoa, 16147
Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta
Milan, 20133
Fondazione Mondino, IRCCS Istituto Neurologico Nazionale a Carattere Scientifico
Pavia, 27100
Ospedale Pediatrico Bambino Gesu - Gianicolo
Rome, 00165
Universita Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A Gemelli - Centro pe...
Rome, 00168
Azienda Ospedaliera Universitaria Integrata Verona - Centro Fibrosi Cistica di Verona (CFC Verona)
Verona, 37126
Australia6 sites
Royal Brisbane and Women's Hospital (RBWH)
Brisbane, Queensland, 4006
Queensland Children's Hospital (Lady Cilento Children's Hospital)
Brisbane, Queensland, 4101
Austin Hospital
Heidelberg, Victoria, 3084
The Royal Children's Hospital (RCH) Melbourne
Parkville, Victoria, 3052
Sydney Children's Hospital - Randwick
Randwick, New South Wales, 2031
The Children's Hospital-Westmead - Heart Centre for Children
Westmead, New South Wales, 2145
China6 sites
Peking University First Hospital (Beida Hospital)
Beijing, Beijing Municipality, 100034
Capital Medical University-Beijing Children's Hospital
Beijing, Beijing Municipality, 100045
Guangzhou Medical University-The Second Affiliated Hospital
Guangzhou, Guangdong, 510260
Fudan University - Children's Hospital
Shanghai Shi, Shanghai Municipality, 201102
Shenzhen Children's Hospital
Shenzhen Shi, Guangdong, 518026
Wuhan Children's Hospital
Wuhan, Hubei, 430016
United Kingdom5 sites
Cardiff and Vale University Health Board - University Hospital of Wales (UHW) - Noah's Ark Childr...
Cardiff, East Wales, CF14 4XW
NHS Greater Glasgow and Clyde-Glasgow Clinical Research Facility - Queen Elizabeth University Hos...
Glasgow, South Western Scotland, G51 4TF
University College London Hospitals NHS Foundation Trust (UCLH)
London, NW1 2PG
Great Ormond Street Hospital for Children NHS Foundation Trust
London, WC1N 3JH
The Newcastle upon Tyne Hospitals NHS Foundation Trust - Royal Victoria Infirmary (RVI)
Newcastle upon Tyne, North East, NE1 4LP
Germany4 sites
Gesellschaft fuer Epilepsieforschung e.V.
Bielefeld, North Rhine-Westphalia, 33617
Universitätsklinikum Bonn
Bonn, North Rhine-Westphalia, 53127
Universitätsklinikum Frankfurt - Klinikum der Goethe-Universität
Frankfurt am Main, 60596
Universitaetsklinikum Schleswig-Holstein (UKSH) - Campus Kiel - Klinik fuer Psychosomatik und Psy...
Kiel, Schleswig-Holstein, 24105
Brazil3 sites
Instituto de Neurologia de Curitiba (INC)
Curitiba, Paraná, 81210-310
Moinhos de Vento Hospital (Hospital Moinhos de Vento) (HMV)
Porto Alegre, Rio Grande do Sul, 90035-001
Universidade de Sao Paulo (USP) - Hospital das Clinicas da Faculdade de Medicina (HCFMUSP) - Inst...
São Paulo, 05403-903
Portugal3 sites
Hospital Pediátrico de Coimbra
Coimbra, 3000-602
Unidade Local de Saude Santa Maria, E.P.E (ULSSM)
Lisbon, 1649-035
Centro Hospitalar Universitario de Santo Antonio - Centro Materno Infantil do Norte (CMIN)
Porto, 4050
Serbia3 sites
Univerzitetski Klinicki Centar Srbije - Klinika za Neurologiju
Belgrade, Beograd, 11000
Institut za Zdravstvenu Zastitu Majke i Deteta Srbije Dr Vukan Cupic
Belgrade, Beograd, 11070
University of Belgrade-Faculty of Medicine - Clinic of Neurology and Psychiatry for Children and ...
Belgrade, Beograd, 112112
Belgium2 sites
Universitair Ziekenhuis Antwerpen (UZA)
Edegem, Antwerp, 2650
Universitaire Ziekenhuizen Leuven - Campus Gasthuisberg
Leuven, Flemish Brabant, 3000
Canada1 site
The Hospital for Sick Children (SickKids)
Toronto, Ontario, M5G 1X8
Latvia1 site
Bernu Kliniska Universitates Slimnica (BKUS) (University Children's Hospital)
Riga, LV-1004
Mexico1 site
Instituto Nacional de Pediatria (INP) (National Institute of Pediatrics)
Mexico City, Mexico City, 04530
Netherlands1 site
Universitair Medisch Centrum Utrecht - Polikliniek Oogheelkunde
Utrecht, 3584 CX
About this study
Official title: 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
This (DEEp OLE Study) is a multicentre, open-label study to investigate the long-term safety, efficacy, tolerability, and pharmacokinetics (PK) of LP352 in the treatment of seizures in children and adults with DEE who completed Study LP352-301 or LP352-302. The study consists of 3 main phases: Screening, Titration period and Maintenance period, followed by a Taper period and Follow-Up. The total duration of the study will be approximately 14 months.
- Being tested
- LP352
- Keywords
- Developmental and Epileptic Encephalopathy, LP352, Bexicaserin, Seizures, DEEp OLE, Antiseizure medications, Epilepsy, Neurodevelopmental disorders, Dravet syndrome, Lennox-gastaut syndrome
- Medical subject headings
- Seizures, Epilepsy, Neurodevelopmental Disorders, Epilepsies, Myoclonic, Lennox Gastaut Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
LP352Drug
Also called Bexicaserin
LP352 will be administered orally or through G-tube/ percutaneous endoscopic gastrostomy (PEG) tube.
| Study group | Role | What they receive |
|---|---|---|
| LP352 | Experimental | Participants will be titrated up to highest tolerated dose of LP352 during the Titration period (Visit 1 - Visit 3), followed by maintenance period (Visit 4 - Visit 14) and then taper/down titration period (Visit 15 - Visit 17). Receives: Drug: LP352 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants reporting Treatment emergent adverse events (TEAEs) and serious adverse events (SAEs) and AEs leading to discontinuation
An AE is defined as any untoward medical occurrence in a participant enrolled into this study, regardless of its causal relationship to the study drug. A treatment-emergent AE is defined as any event that is not present before exposure to study drug or any event or condition that is already present that worsens in either intensity or frequency after exposure to study drug. An SAE is defined as any event that: Results in death; Is life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization. "Inpatient hospitalization" includes admission to an emergency room for observation and/or treatment that would have been insufficient in an outpatient setting; results in persistent or significant disability/incapacity; Is a congenital anomaly/birth defect or is an important medical event. An adverse event of special interest (AESI) is an AE or SAE is defined as an AE or SAE of scientific or medical concern specific to the sponsor's product or program.
Measured: Up to 61 Weeks
Number of Participants With Clinically Significant Changes in Chemistry parameters
Measured: Up to 61 Weeks
Number of Participants With Clinically Significant Changes in Hematology parameters
Measured: Up to 61 Weeks
Number of Participants With Clinically Significant Changes in Urinalysis
Measured: Up to 61 Weeks
Number of participants with clinically significant changes in vital signs
Measured: Up to 61 Weeks
Number of participants with clinically significant changes in physical examinations
Measured: Up to 61 Weeks
Number of participants with clinically significant changes in growth parameters
Measured: Up to 61 Weeks
Number of participants with clinically significant changes in electrocardiogram (ECG) parameters
Measured: Up to 61 Weeks
Number of participants with postive responses to Columbia-Suicide Severity Rating Scale (C-SSRS)
C-SSRS was developed by researchers at Columbia University as a tool to help systematically assess suicidal ideation and behavior. It is composed of questions addressing suicidal ideation and suicidal behavior, as well as self-injurious behavior without suicidal intent. The tool will be administered by a trained operator/interviewer (investigator or designee) via interview with the participant at the study time points. If the participant is unable to complete the C-SSRS due to developmental status, the participant's legally acceptable representative may not complete the C SSRS. In these cases, the investigator may use clinical judgment to assess both the participant's status regarding suicidality and ability to complete the scale, both of which must then be documented in the source document.
Measured: Up to 61 Weeks
Number of participants with positive responses to Patient Health Questionnaire-9 (PHQ-9) and Question 9
The PHQ-9 is a multipurpose instrument for Screening, diagnosing, monitoring, and measuring the severity of depression. The scale is an easy-to-use participant questionnaire that is a self-administered version of the Primary Care Evaluation of Mental Disorders diagnostic instrument for common mental disorders. The PHQ-9 is the depression module, which scores each of the 9 Diagnostic and Statistical Manual of Mental Disorders IV, Text Revision criteria as "0" (not at all) to "3" (nearly every day). It has been validated for use in primary care. Participants with a depression score of greater than 9 (mild) on the PHQ-9 scale or a positive response to Question 9 should be excluded from the study. When there is a positive response to PHQ-9 Question 9 post randomization, the investigator should determine whether an AE has occurred.
Measured: Up to 61 Weeks
Secondary outcomes (3)
Frequency Percent Change in Countable Motor Seizures During Treatment Compared to Baseline
The percent change from Baseline in countable motor seizure frequency during Treatment will be calculated as (countable motor seizure frequency during Treatment) - (countable motor seizure frequency during Baseline [Visit 1 of LP352-301 and LP352-302]) ÷ seizure frequency during Baseline [Visit 1 of LP352-301 and LP352-302]) × 100
Measured: Baseline and up to 55 weeks
Percentage of participants with ≥ 50% Reduction in countable motor seizures during Treatment compared to Baseline [Visit 1 of LP352-301 and LP352-302]
Measured: Baseline and up to 55 weeks
Frequency Percent Change in Countable Motor Seizures during Maintenance compared to Baseline [Visit 1 of LP352-301 and LP352-302]
Measured: Baseline and up to 55 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Apr 2025
- Study start12 Feb 2025
- Primary completion11 Nov 2027 (estimated)
- Study completion17 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Developmental and Epileptic EncephalopathyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 324 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Longboard Pharmaceuticals
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06908226
- Sponsor's protocol ID
- LP352-303
- Other IDs
- 2024-514974-39-00
- Status last verified
- Oct 2026
- First submitted
- 6 Mar 2025
- Last updated
- 14 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 14 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT06908226
- Acronym / sponsor ID
- LP352-303
- Keywords
- Developmental and Epileptic Encephalopathy, LP352, Bexicaserin, Seizures, DEEp OLE, Antiseizure medications, Epilepsy, Neurodevelopmental disorders
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 324 participants (estimated)
- Lead sponsor
- Longboard PharmaceuticalsIndustry (pharma, biotech, devices)
- Study start
- 12 Feb 2025 (actual)
- Primary completion
- 11 Nov 2027 (estimated)
- Study completion
- 17 Dec 2027 (estimated)
- First posted
- 3 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This (DEEp OLE Study) is a multicentre, open-label study to investigate the long-term safety, efficacy, tolerability, and pharmacokinetics (PK) of LP352 in the treatment of seizures in children and adults with DEE who completed Study LP352-301 or LP352-302. The study consists of 3 main phases: Screening, Titration period and Maintenance period, followed by a Taper period and Follow-Up. The total duration of the study will be approximately 14 months.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| LP352 | Experimental | Drug: LP352Participants will be titrated up to highest tolerated dose of LP352 during the Titration period (Visit 1 - Visit 3), followed by maintenance period (Visit 4 - Visit 14) and then taper/down titration period (Visit 15 - Visit 17). |
Who may qualify
- Ages
- 2 to 66 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (10 listed)
- 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).
- Participant has a body weight of ≥10 kg.
- G-tubes/PEG tubes (if applicable) should be in stable and good working condition. Nasogastric tubes are not allowed except for short-term management.
- Has at least one reliable and consistent parent, legal guardian, or caregiver during the study.
Key exclusion criteria (13 listed)
- The participant is receiving exclusionary medications.
- Considered at risk of suicidal behavior based on the C-SSRS at Visit 8 of LP352-301 or LP352-302. If the participant is unable to complete the C-SSRS due to developmental status, the participant's LAR may not complete the C-SSRS. In these cases, the investigator may use clinical judgment to assess both the participant's status regarding suicidality and the ability to complete the scale, both of which must then be documented in the source document.
- Has a PHQ-9 score of >9 or a positive response to Question 9 at Visit 8 of LP352-301 or LP352-302. If the participant is unable to complete the PHQ-9, the participant's LAR may not complete the PHQ-9. In these cases, the investigator may use clinical judgment to assess both the participant's status and ability to complete the scale, both of which must then be documented in the source document.
- Ongoing AE from LP352-301 or LP352-302 of severe depression, anorexia nervosa, or bulimia per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.
- Has an abnormal and clinically significant 12-lead ECG at Visit 8 in LP352-301 or LP352-302 in the opinion of the investigator, for example, second- or third-degree heart block or a QTc of >450 msec for adult males, >470 msec for adult females, or >440 msec for pediatric participants.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| LP352Also: BexicaserinLP352 will be administered orally or through G-tube/ percutaneous endoscopic gastrostomy (PEG) tube. | Drug | LP352 |
Primary outcome
Number of participants reporting Treatment emergent adverse events (TEAEs) and serious adverse events (SAEs) and AEs leading to discontinuation
Time frame: Up to 61 Weeks
An AE is defined as any untoward medical occurrence in a participant enrolled into this study, regardless of its causal relationship to the study drug. A treatment-emergent AE is defined as any event that is not present before exposure to study drug or any event or condition that is already present that worsens in either intensity or frequency after exposure to study drug. An SAE is defined as any event that: Results in death; Is life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization. "Inpatient hospitalization" includes admission to an emergency room for observation and/or treatment that would have been insufficient in an outpatient setting; results in persistent or significant disability/incapacity; Is a congenital anomaly/birth defect or is an important medical event. An adverse event of special interest (AESI) is an AE or SAE is defined as an AE or SAE of scientific or medical concern specific to the sponsor's product or program.
Number of Participants With Clinically Significant Changes in Chemistry parameters
Time frame: Up to 61 Weeks
Number of Participants With Clinically Significant Changes in Hematology parameters
Time frame: Up to 61 Weeks
Number of Participants With Clinically Significant Changes in Urinalysis
Time frame: Up to 61 Weeks
Number of participants with clinically significant changes in vital signs
Time frame: Up to 61 Weeks
Number of participants with clinically significant changes in physical examinations
Time frame: Up to 61 Weeks
Number of participants with clinically significant changes in growth parameters
Time frame: Up to 61 Weeks
Number of participants with clinically significant changes in electrocardiogram (ECG) parameters
Time frame: Up to 61 Weeks
Number of participants with postive responses to Columbia-Suicide Severity Rating Scale (C-SSRS)
Time frame: Up to 61 Weeks
C-SSRS was developed by researchers at Columbia University as a tool to help systematically assess suicidal ideation and behavior. It is composed of questions addressing suicidal ideation and suicidal behavior, as well as self-injurious behavior without suicidal intent. The tool will be administered by a trained operator/interviewer (investigator or designee) via interview with the participant at the study time points. If the participant is unable to complete the C-SSRS due to developmental status, the participant's legally acceptable representative may not complete the C SSRS. In these cases, the investigator may use clinical judgment to assess both the participant's status regarding suicidality and ability to complete the scale, both of which must then be documented in the source document.
Number of participants with positive responses to Patient Health Questionnaire-9 (PHQ-9) and Question 9
Time frame: Up to 61 Weeks
The PHQ-9 is a multipurpose instrument for Screening, diagnosing, monitoring, and measuring the severity of depression. The scale is an easy-to-use participant questionnaire that is a self-administered version of the Primary Care Evaluation of Mental Disorders diagnostic instrument for common mental disorders. The PHQ-9 is the depression module, which scores each of the 9 Diagnostic and Statistical Manual of Mental Disorders IV, Text Revision criteria as "0" (not at all) to "3" (nearly every day). It has been validated for use in primary care. Participants with a depression score of greater than 9 (mild) on the PHQ-9 scale or a positive response to Question 9 should be excluded from the study. When there is a positive response to PHQ-9 Question 9 post randomization, the investigator should determine whether an AE has occurred.
3 secondary outcomes
Frequency Percent Change in Countable Motor Seizures During Treatment Compared to Baseline
Time frame: Baseline and up to 55 weeks
Percentage of participants with ≥ 50% Reduction in countable motor seizures during Treatment compared to Baseline [Visit 1 of LP352-301 and LP352-302]
Time frame: Baseline and up to 55 weeks
Frequency Percent Change in Countable Motor Seizures during Maintenance compared to Baseline [Visit 1 of LP352-301 and LP352-302]
Time frame: Baseline and up to 55 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Oct 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
The record lists no contact. Use the official record to reach the sponsor.
88 sites in 17 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing LP352 in people with Developmental and Epileptic Encephalopathy, run by Longboard Pharmaceuticals at 88 sites in 17 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 10 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: enrolling by invitation, as of the sponsor's last update on 14 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 88 sites in United States, Spain, Japan, France, Italy and 12 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of participants reporting Treatment emergent adverse events (TEAEs) and serious adverse events (SAEs) and AEs leading to discontinuation (time frame: Up to 61 Weeks). The study lists 10 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Oct 2026.