TerminatedPhase 3

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

Stopped: Due to negative results from phase 3 SKYLINE and SKYWAY studies and unrelated to patient safety it has been determined that supplementary data from TAK-935-3003 study is no longer necessary. Therefore, Takeda has made a decision to close this study

United States, Australia, Belgium352 participantsStarted 2022-03-04

Plain-language 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.

Who can participate

Age range

2 Years – 56 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Exclusion criteria

. 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.
. 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.
. 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.

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Number of Participants With At Least One Treatment Emergent Adverse Event (TEAE)

Timeframe: Up to end of study (approximately 3.6 years)

Number of Participants in Each Category of the Columbia-Suicide Severity Rating Scale (C-SSRS) Over Time

Timeframe: At first visit post-baseline (Visit 1 [V1], Day 1 of the current study), Week 13 (V4), Week 26 (V5), Week 52 (V7), Week 78 (V9), Week104 (v11), Week 130 (V12) and Week 156 (V13)

Change From Baseline in Body Weight for All Age Groups

Timeframe: From Baseline to Week 104

Change From Baseline in Height for All Age Groups

Timeframe: Baseline to Week 104

Number of Participants in Each Tanner Stage for Children 6 to 17 Years of Age During the Study

Timeframe: From Baseline to Week 130

Absolute Value for Insulin-like Growth Factor 1 (IGF-1) for Children 2 to 17 Years of Age During the Study

Timeframe: From Baseline to Week 130

Trial details

NCT IDNCT05163314

SponsorTakeda

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2025-09-24

Results submitted2026-02-26

View on ClinicalTrials.gov More Dravet Syndrome (DS) trials

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

United States, Australia, Belgium352 participantsStarted 2022-03-04

Plain-language summary

Who can participate

Age range

2 Years – 56 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Exclusion criteria

. 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.
. 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.
. 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.

What they're measuring

Number of Participants With At Least One Treatment Emergent Adverse Event (TEAE)

Timeframe: Up to end of study (approximately 3.6 years)

Number of Participants in Each Category of the Columbia-Suicide Severity Rating Scale (C-SSRS) Over Time

Timeframe: At first visit post-baseline (Visit 1 [V1], Day 1 of the current study), Week 13 (V4), Week 26 (V5), Week 52 (V7), Week 78 (V9), Week104 (v11), Week 130 (V12) and Week 156 (V13)

Change From Baseline in Body Weight for All Age Groups

Timeframe: From Baseline to Week 104

Change From Baseline in Height for All Age Groups

Timeframe: Baseline to Week 104

Number of Participants in Each Tanner Stage for Children 6 to 17 Years of Age During the Study

Timeframe: From Baseline to Week 130

Absolute Value for Insulin-like Growth Factor 1 (IGF-1) for Children 2 to 17 Years of Age During the Study

Timeframe: From Baseline to Week 130