Skip to content

A Study of Soticlestat as an Add-on Therapy in Children and Adults With Dravet Syndrome or Lennox-Gastaut Syndrome

A Phase 3, Prospective, Open-Label, Multisite, Extension of Phase 3 Studies To Assess the Long-Term Safety and Tolerability of Soticlestat as Adjunctive Therapy in Subjects With Dravet Syndrome or Lennox-Gastaut Syndrome (ENDYMION 2)

Status
Terminated
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05163314
Enrollment
352
Registered
2021-12-20
Start date
2022-03-04
Completion date
2025-09-24
Last updated
2025-10-08

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Dravet Syndrome (DS), Lennox Gastaut Syndrome (LGS)

Keywords

Drug Therapy

Brief summary

The main aim of the study is to learn if soticlestat, when given as an add-on therapy, reduces the number of seizures in children and adults with Dravet Syndrome (DS) or Lennox-Gastaut Syndrome (LGS). Participants will receive their standard anti-seizure therapy, plus tablets of soticlestat. There will be scheduled visits and follow-up phone calls throughout the study.

Detailed description

The drug being tested in this study is called soticlestat (TAK-935). Soticlestat administered long-term in pediatric and adult participants who participated in an antecedent soticlestat Phase 3 clinical study will be assessed for additional safety and tolerability data along with efficacy analysis, as well as palatability and acceptability of soticlestat in the pediatric population. The study will enroll approximately 400 participants. All participants will receive soticlestat based on their weight in the 2-week Titration Period (for participants who roll over from an antecedent double-blind study). Following the Titration Period, participants will continue to receive the same dose in the Maintenance Period. At the end of maintenance period, the dose will be down-tapered (unless already at the lowest dose) and then stopped. Participants not tolerating minimum dose of 100 mg twice a day (BID) will be discontinued from the study. This multi-center trial will be conducted worldwide. The overall time to participate in the study will be approximately 4 years, or until the study is stopped at the discretion of the sponsor, or the product is approved and launched. Participants who discontinue study drug treatment before the completion of the study, will continue to be followed per protocol and maintain a daily seizure diary until the final follow-up phone call.

Interventions

Soticlestat mini-tablets or tablets

Sponsors

Takeda
Lead SponsorINDUSTRY

Study design

Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
2 Years to 56 Years
Healthy volunteers
No

Inclusion criteria

1\. Participant must have: * Been previously enrolled in a phase 3 soticlestat clinical study.

Exclusion criteria

1. Unstable, clinically significant neurologic (other than the disease being studied), psychiatric, cardiovascular, ophthalmologic, pulmonary, hepatic, renal, metabolic, gastrointestinal, urologic, immunologic, hematopoietic, endocrine disease, malignancy including progressive tumors, or other abnormality that may impact the ability to participate in the study or that may potentially confound the study results. It is the responsibility of the investigator to assess the clinical significance; however, consultation with the medical monitor may be warranted. 2. Abnormal and clinically significant ECG abnormality at Visit 1 including QT interval with Fridericia correction method (QTcF) \>450 milliseconds (ms) confirmed with a repeat ECG using manual measurement of QTcF. 3. Participant is considered by the investigator to be at imminent risk of suicide or injury to self, others, or property. Participants who have positive answers on item numbers 4 or 5 on the CSSRS before dosing are excluded. This scale will only be administered to participants aged ≥6 years.

Design outcomes

Primary

MeasureTime frameDescription
Number of Participants With At Least One Treatment Emergent Adverse Event (TEAE)Up to 4 yearsAn Adverse Event (AE) is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (example, a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug, whether or not it is considered related to the drug. A TEAE is any AE either reported for the first time or worsening of a pre-existing event after first dose of study drug and within 30 days of the last administration of study drug.
Change from Baseline in Columbia-Suicide Severity Rating Scale (C-SSRS) ScoreUp to 4 yearsC-SSRS systematically tracks suicidal ideation and behavior. The total score range is 0 (no ideation is present) to 5 (active suicidal ideation with specific plan and intent). The higher the score, the greater one's suicidal ideation.
Change from Baseline in Body Weight for All Age GroupsUp to 4 years
Change from Baseline in Height for All Age GroupsUp to 4 years
Absolute Value for Tanner Stage for Children 6 to 17 Years of Age During the StudyUp to 4 yearsTanner assessment score is used to document the stage of development of puberty by assessing the secondary sexual characteristics, rated in 5 stages: stage 1 (no development) to 5 (adult-like development in quantity and size).
Absolute Value for Insulin-like Growth Factor 1 (IGF-1) for Children 2 to 17 Years of Age During the StudyUp to 4 years

Secondary

MeasureTime frameDescription
CGI-I Nonseizure Symptoms ScoreUp to 4 yearsThe CGI-I nonseizure symptoms instrument is a series of single-item assessments that the investigator uses to rate improvement in the symptoms and impacts in select nonseizure domains since initiating the study drug. The participant will be rated on 7-point scale by the investigator as follows: 1 (very much improved), 2 (much improved), 3 (minimally improved), 4 (no change), 5 (minimally worse), 6 (much worse), and 7 (very much worse). At Baseline, a symptoms form is completed by the clinician in collaboration with the primary caregiver to assess the participants status based on the presence of any nonseizure symptoms. Higher score will indicate worse symptoms.
Percent Change from Baseline in Total Seizure Frequency per 28 Days for DS and LGS ParticipantsUp to 4 yearsSeizure frequency per 28 days is defined as total number of seizures reported during the period divided by number of days during the period seizures were assessed multiplied by 28. Percent change from Baseline is defined as (frequency of seizures per 28 days during Treatment Period - frequency of seizures per 28 days at Baseline) divided by the frequency of seizures per 28 days at Baseline multiplied by 100.
Change in Quality of Life Inventory-Disability (QI-Disability) ScoreUp to 4 yearsThe QI-Disability tool is a parent/caregiver-reported questionnaire that evaluates quality of life in children with intellectual disabilities. It contains 32 items covering 6 domains of quality of life: physical health, positive emotions, negative emotions, social interaction, leisure and the outdoors, and independence. Scores are from a 5-point Likert scale and then are transformed to a scale of 0 to 100. Possible scores range from 0-100, with higher scores indicating better quality of life.
Percent Change from Baseline in Convulsive Seizure Frequency per 28 Days in DS CohortUp to 4 yearsConvulsive seizure frequency per 28 days is defined as total number of convulsive seizures reported during the period divided by number of days during the period seizures were assessed multiplied by 28. Percent change from Baseline will be defined as (frequency of convulsive seizures per 28 days during Treatment Period - frequency of convulsive seizures per 28 days at Baseline) divided by the frequency of convulsive seizures per 28 days at Baseline multiplied by 100.
Percent Change from Baseline in Major Motor Drop (MMD) Seizure Frequency per 28 Days in LGS CohortUp to 4 yearsMMD seizure frequency per 28 days is defined as total number of MMD seizures reported during the period divided by number of days during the period seizures were assessed multiplied by 28. Percent change from Baseline will be defined as (frequency of MMD seizures per 28 days during the Treatment Period - frequency of MMD seizures per 28 days at Baseline) divided by the frequency of MMD seizures per 28 days at Baseline multiplied by 100.
Clinical Global Impression of Improvement (CGI-I) ScoreUp to 4 yearsThe CGI-I Clinician is a 7-point Likert scale that the investigator uses to rate a participant's change (improvement) in overall seizure control, behavior, safety and tolerability, after the initiation of study drug relative to Baseline (before treatment with study drug). The participant will be rated as follows: 1 (very much improved), 2 (much improved), 3 (minimally improved), 4 (no change), 5 (minimally worse), 6 (much worse), and 7 (very much worse). Higher score will indicate worse symptoms.
Caregiver Global Impression of Improvement (Care GI-I) ScoreUp to 4 yearsThe Care GI-I is a 7-point Likert scale that the caregiver uses to rate improvement in overall seizure control, behavior, safety and tolerability after the initiation of study drug relative to Baseline (before treatment with study drug). The participant will be rated as follows: 1 (very much improved), 2 (much improved), 3 (minimally improved), 4 (no change), 5 (minimally worse), 6 (much worse), and 7 (very much worse). The parent/caregiver will complete the Care GI-I via interview. Higher score will indicate worse symptoms.
CGI-I Seizure Intensity and Duration ScoreUp to 4 yearsThe CGI-I seizure intensity and duration instrument is used by the parent/caregiver to rate improvement in intensity and duration of convulsive seizures (DS Cohort) or MMD seizures (LGS Cohort) from Baseline. The participant's symptoms will be rated on 7-point scale as follows: 1 (very much improved), 2 (much improved), 3 (minimally improved), 4 (no change), 5 (minimally worse), 6 (much worse), and 7 (very much worse). Higher score will indicate worse symptoms.

Countries

Australia, Belgium, Brazil, Canada, China, France, Germany, Greece, Hungary, Italy, Japan, Latvia, Mexico, Netherlands, Poland, Russia, Serbia, Spain, Ukraine, United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 6, 2026