A Phase 2 interventional study of TAK-935 and Placebo in Epilepsy, Dravet Syndrome and Lennox-Gastaut Syndrome, sponsored by Takeda. Completed at 44 sites in 8 countries. Open to participants aged 2 Years to 17 Years. Per ClinicalTrials.gov, last updated 2026-09-14.
Sponsored by Takeda · Phase 2, Interventional, and Treatment
The purpose of this study is to investigate the effect on the frequency of all seizures (convulsive and drop) in participants treated with TAK-935 compared to placebo.
The drug being tested in this study is called TAK-935 (OV935). This randomized, double-blind study will assess the effects of TAK-935 (OV935), compared to placebo, on efficacy, safety, and tolerability in pediatric participants with Dravet syndrome (DS) or Lennox Gastaut syndrome (LGS). This multi-center trial will be conducted worldwide and will enroll approximately 126 participants.
Participants will be randomized based on their diagnosis in 2 categories; DS or LGS. The study will consist of 2 periods: Screening Period and Treatment Period. The overall duration of Treatment Period is up to 20 weeks including 8-week Dose Optimization Period and 12-week Maintenance Period. The overall time to participants in this study is approximately 30 weeks.
Participants completing this study will have an option to enroll in the open-label extension study, under a separate protocol.
1,848 studies on the registry are indexed under Epilepsy; 422 are open to participants now.
This study's enrollment of 141 is above the median of 50 across 1,239 interventional studies indexed under Epilepsy.
Browse Epilepsy studies →Takeda is the lead sponsor of 1,026 studies on the registry; 89 are open to participants now.
Of its 178 completed or terminated interventional studies of FDA-regulated products, 154 (87%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
TAK-935 placebo-matching tablets, orally or via gastrostomy tube (G-tube)/percutaneous endoscopic gastrostomy (PEG), twice a day (BID) up to Week 20.
Drug: Placebo
TAK-935 tablets orally or via G-tube/PEG tube, BID. Participants weighing \<60 kg received total daily dose of study drug calculated based on body weight. Participants weighing ≥60 kg at Baseline, were administered with 200 mg/day followed by 400 mg/day, then 600 mg/day, up to Week 20.
Drug: TAK-935
TAK-935 tablets or mini-tablets.
TAK-935 placebo-matching tablets or mini-tablets.
Percent Change From Baseline in Seizure Frequency Per 28 Days During the Maintenance Period
Seizure frequency per 28 days is defined as total number of seizures (convulsive seizures for DS, drop seizures for LGS) 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 maintenance period - frequency of seizures per 28 days at baseline) divided by frequency of seizures per 28 days at baseline multiplied by 100. Negative percent change from Baseline indicates improvement.
Time frame: Baseline; Maintenance Period: Weeks 9 to 20
Percent Change From Baseline in Seizure Frequency Per 28 Days During the Treatment Period
Seizure Frequency per 28 days is defined as total number of Seizures reported (convulsive seizures for DS, drop seizures for LGS) 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 frequency of seizures per 28 days at baseline multiplied by 100. Negative percent change from Baseline indicates improvement.
Time frame: Baseline; Treatment Period: Weeks 0 to 20
Percent Change From Baseline in Convulsive Seizure Frequency Per 28 Days in Participants With Dravet Syndrome Stratum During the Maintenance Period
Convulsive 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 (%) is defined as \[(Maintenance Period Convulsive Seizure Frequency - Baseline Period Convulsive Seizure Frequency) divided by Baseline Convulsive Seizure Frequency\] multiplied by 100. Negative percent change from Baseline indicates improvement.
Time frame: Baseline; Maintenance Period: Weeks 9 to 20
Percent Change From Baseline in Drop Seizure Frequency Per 28 Days in Participants With the Lennox-Gastaut Syndrome (LGS) Stratum During the Maintenance Period
Drop seizure frequency per 28 days is defined as total number of drop 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 \[(Maintenance Period Drop Seizure Frequency - Baseline Period Drop Seizure Frequency) divided by Baseline Drop Seizure Frequency\] multiplied by 100. Negative percent change from Baseline indicates improvement.
Time frame: Baseline; Maintenance Period: Weeks 9 to 20
Percentage of Participants With LGS Stratum Considered Treatment Responders Throughout the Maintenance Period
Responders are defined as having over 50% drop seizure reduction compared to Baseline. Percent Reduction from Baseline (%) is defined as \[(Maintenance Period Drop Seizure Frequency - Baseline Period Drop Seizure Frequency) divided by Baseline Drop Seizure Frequency\] multiplied by 100. Data is reported as reduction of 25%, 50%, 75% and 100% or more in drop seizures from Baseline.
Time frame: Maintenance Period: Weeks 9 to 20
Percentage of Participants With Dravet Syndrome Stratum Considered Treatment Responders Throughout the Maintenance Period
Responders are defined as having over 50% convulsive seizure reduction compared to Baseline. Percent Reduction from Baseline (%) is defined as \[(Maintenance Period Convulsive Seizure Frequency - Baseline Period Convulsive Seizure Frequency) divided by Baseline Convulsive Seizure Frequency\] multiplied by 100. Data is reported as reduction of 25%, 50%, 75% and 100% or more in drop seizures from Baseline.
Time frame: Maintenance Period: Weeks 9 to 20
Change From Baseline in Clinician's Clinical Global Impression of Severity (CGI-S) Responses of Investigator Reported Impression of Efficacy and Tolerability of Study Drug
The CGI-Severity (CGI-S) focuses on clinicians' observations of the participant's cognitive, functional, and behavioral performance since the beginning of the study. The CGI-S is rated on a 7-point scale, with the severity of illness scale using a range of responses from 1 (normal) through to 7 (amongst the most severely ill participants). A negative change from Baseline indicates improvement.
Time frame: Baseline and Week 20
Percentage of Participants With Clinical Global Impression of Change (CGI-C) Responses as Per the Investigator Reported Impression of Efficacy and Tolerability TAK-935
CGI-Change (CGI-C) treatment response ratings should take account of both therapeutic efficacy and treatment-related AEs. Each component of the CGI is rated separately; the instrument does not yield a global score. The CGI-C is rated on a 7-point scale, where, 0 = Marked improvement and no side-effects, 1 = Marked improvement and minimal side-effects, 2 = No Change, 3 = Minimal improvement and marked side-effects and 4 = Unchanged or worse and side-effects outweigh the therapeutic effect. Lower scores indicated improvement.
Time frame: Week 20
Percentage of Participants With Caregiver Global Impression of Change (Care GI-C) Responses as Per the Parent/Family Reported Impression of Efficacy and Tolerability of TAK-935
The Care GI-C is rated on a 7-point scale, with the severity of illness scale where, 1 = Very much improved, 2 = Much improved, 3 = Slightly improved, 4 = No change, 5 = Slightly worse, 6 = Much worse and 7 = Very much worse. Lower scores indicated improvement.
Time frame: Week 20
Change From Baseline in Plasma 24S-Hydroxycholesterol (24HC) Levels in Participants Treated With TAK-935 as an Adjunctive Therapy
A negative change from Baseline indicates improvement.
Time frame: Baseline and Week 24
Change From Baseline in Seizure Frequency in Participants Treated With TAK-935 as an Adjunctive Therapy
Seizure frequency was based on convulsive seizures for the participants in the Dravet Syndrome Indication and Drop Seizures for the participants in the LGS Indication. Seizure frequency per 28 days = (total number of seizures reported during the period) / (number of days during the period seizures were assessed) \* 28. A negative change from Baseline indicates improvement.
Time frame: Baseline and Week 20
Participants took part in the study at 45 investigative sites globally from 8 August 2018 to 20 July 2020.
| Milestone | Placebo | TAK-935 |
|---|---|---|
| Started | 70 | 71 |
| Completed | 60 | 66 |
| Not completed | 10 | 5 |
| Withdrew: Physician decision | 1 | 0 |
| Withdrew: Withdrawal by parent/guardian | 3 | 1 |
| Withdrew: Adverse event | 3 | 4 |
| Withdrew: Early withdrawal from study treatment | 3 | 0 |
Seizure frequency per 28 days is defined as total number of seizures (convulsive seizures for DS, drop seizures for LGS) 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 maintenance period - frequency of seizures per 28 days at baseline) divided by frequency of seizures per 28 days at baseline multiplied by 100. Negative percent change from Baseline indicates improvement.
| percent change | Placebo | TAK-935 |
|---|---|---|
| Percent Change From Baseline in Seizure Frequency Per 28 Days During the Maintenance Period | 3.11 (-78.8 to 163.0) | -27.76 (-100.0 to 160.6) |
Seizure Frequency per 28 days is defined as total number of Seizures reported (convulsive seizures for DS, drop seizures for LGS) 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 frequency of seizures per 28 days at baseline multiplied by 100. Negative percent change from Baseline indicates improvement.
| percent change | Placebo | TAK-935 |
|---|---|---|
| Percent Change From Baseline in Seizure Frequency Per 28 Days During the Treatment Period | 0.75 (-60.1 to 437.8) | -30.05 (-100.0 to 347.5) |
Convulsive 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 (%) is defined as \[(Maintenance Period Convulsive Seizure Frequency - Baseline Period Convulsive Seizure Frequency) divided by Baseline Convulsive Seizure Frequency\] multiplied by 100. Negative percent change from Baseline indicates improvement.
| percent change | Placebo | TAK-935 |
|---|---|---|
| Percent Change From Baseline in Convulsive Seizure Frequency Per 28 Days in Participants With Dravet Syndrome Stratum During the Maintenance Period | 9.38 (-47.3 to 153.5) | -36.50 (-100.0 to 84.1) |
Drop seizure frequency per 28 days is defined as total number of drop 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 \[(Maintenance Period Drop Seizure Frequency - Baseline Period Drop Seizure Frequency) divided by Baseline Drop Seizure Frequency\] multiplied by 100. Negative percent change from Baseline indicates improvement.
| percent change | Placebo | TAK-935 |
|---|---|---|
| Percent Change From Baseline in Drop Seizure Frequency Per 28 Days in Participants With the Lennox-Gastaut Syndrome (LGS) Stratum During the Maintenance Period | -1.90 (-78.8 to 163.0) | -18.46 (-100.0 to 160.6) |
Responders are defined as having over 50% drop seizure reduction compared to Baseline. Percent Reduction from Baseline (%) is defined as \[(Maintenance Period Drop Seizure Frequency - Baseline Period Drop Seizure Frequency) divided by Baseline Drop Seizure Frequency\] multiplied by 100. Data is reported as reduction of 25%, 50%, 75% and 100% or more in drop seizures from Baseline.
| percentage of participants | Placebo | TAK-935 |
|---|---|---|
| Reduction of 25% or More in Drop Seizures from Baseline | 29.7 (15.9 to 47.0) | 42.5 (27.0 to 59.1) |
| Reduction of 50% or More in Drop Seizures from Baseline | 16.2 (6.2 to 32.0) | 27.5 (14.6 to 43.9) |
| Reduction of 75% or More in Drop Seizures from Baseline | 2.7 (0.1 to 14.2) | 10.0 (2.8 to 23.7) |
| Reduction of 100% in Drop Seizures from Baseline | 0 (0.0 to 9.5) | 5.0 (0.6 to 16.9) |
Responders are defined as having over 50% convulsive seizure reduction compared to Baseline. Percent Reduction from Baseline (%) is defined as \[(Maintenance Period Convulsive Seizure Frequency - Baseline Period Convulsive Seizure Frequency) divided by Baseline Convulsive Seizure Frequency\] multiplied by 100. Data is reported as reduction of 25%, 50%, 75% and 100% or more in drop seizures from Baseline.
| percentage of participants | Placebo | TAK-935 |
|---|---|---|
| Reduction of 25% or More in Convulsive Seizures from Baseline | 13.6 (2.9 to 34.9) | 66.7 (44.7 to 84.4) |
| Reduction of 50% or More in Convulsive Seizures from Baseline | 0 (0.0 to 15.4) | 41.7 (22.1 to 63.4) |
| Reduction of 75% or More in Convulsive Seizures from Baseline | 0 (0.0 to 15.4) | 20.8 (7.1 to 42.2) |
| Reduction of 100% in Convulsive Seizures from Baseline | 0 (0.0 to 15.4) | 8.3 (1.0 to 27.0) |
The CGI-Severity (CGI-S) focuses on clinicians' observations of the participant's cognitive, functional, and behavioral performance since the beginning of the study. The CGI-S is rated on a 7-point scale, with the severity of illness scale using a range of responses from 1 (normal) through to 7 (amongst the most severely ill participants). A negative change from Baseline indicates improvement.
| score on scale | Placebo | TAK-935 |
|---|---|---|
| Change From Baseline in Clinician's Clinical Global Impression of Severity (CGI-S) Responses of Investigator Reported Impression of Efficacy and Tolerability of Study Drug | -0.3 ± 0.15 | -0.2 ± 0.14 |
CGI-Change (CGI-C) treatment response ratings should take account of both therapeutic efficacy and treatment-related AEs. Each component of the CGI is rated separately; the instrument does not yield a global score. The CGI-C is rated on a 7-point scale, where, 0 = Marked improvement and no side-effects, 1 = Marked improvement and minimal side-effects, 2 = No Change, 3 = Minimal improvement and marked side-effects and 4 = Unchanged or worse and side-effects outweigh the therapeutic effect. Lower scores indicated improvement.
| percentage of participants | Placebo | TAK-935 |
|---|---|---|
| Week 20, Score 0 | 12.2 | 17.2 |
| Week 20, Score 1 | 2.0 | 15.5 |
| Week 20, Score 2 | 85.7 | 65.5 |
| Week 20, Score 3 | 0 | 0 |
| Week 20, Score 4 | 0 | 1.7 |
The Care GI-C is rated on a 7-point scale, with the severity of illness scale where, 1 = Very much improved, 2 = Much improved, 3 = Slightly improved, 4 = No change, 5 = Slightly worse, 6 = Much worse and 7 = Very much worse. Lower scores indicated improvement.
| percentage of participants | Placebo | TAK-935 |
|---|---|---|
| Week 20, Score 1 | 2.0 | 13.8 |
| Week 20, Score 2 | 12.2 | 10.3 |
| Week 20, Score 3 | 18.4 | 32.8 |
| Week 20, Score 4 | 55.1 | 37.9 |
| Week 20, Score 5 | 8.2 | 3.4 |
| Week 20, Score 6 | 4.1 | 1.7 |
| Week 20, Score 7 | 0 | 0 |
A negative change from Baseline indicates improvement.
| mg/dL | Placebo | TAK-935 |
|---|---|---|
| Baseline | 102.77 ± 50.385 | 102.20 ± 62.332 |
| Change from Baseline at Week 24 | — | -0.10 ± NA |
Seizure frequency was based on convulsive seizures for the participants in the Dravet Syndrome Indication and Drop Seizures for the participants in the LGS Indication. Seizure frequency per 28 days = (total number of seizures reported during the period) / (number of days during the period seizures were assessed) \* 28. A negative change from Baseline indicates improvement.
| seizures per 28 days | Placebo | TAK-935 |
|---|---|---|
| Baseline | 31.00 (3.1 to 1040.1) | 32.12 (2.6 to 5187.7) |
| Change from Baseline at Week 20 | 0.30 (-84.9 to 520.4) | -6.29 (-1024.3 to 77.7) |
Collected over From the first dose to 30 days post-last dose of study treatment (Up to 24 weeks). Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Placebo | 0/70 (0%) | 13/70 (18.6%) | 52/70 (74.3%) |
| TAK-935 | 0/71 (0%) | 11/71 (15.5%) | 55/71 (77.5%) |
| Event | Placebo | TAK-935 |
|---|---|---|
| Upper respiratory tract infectionInfections and infestations | 4/70 | 2/71 |
| Generalised tonic-clonic seizureNervous system disorders | 2/70 | 0/71 |
| SeizureNervous system disorders | 2/70 | 2/71 |
| BronchiolitisInfections and infestations | 1/70 | 0/71 |
| BronchitisInfections and infestations | 1/70 | 1/71 |
| Ear infectionInfections and infestations | 1/70 | 0/71 |
| PneumoniaInfections and infestations | 1/70 | 1/71 |
| Seizure clusterNervous system disorders | 1/70 | 0/71 |
| Status epilepticusNervous system disorders | 1/70 | 1/71 |
| Foreign body in gastrointestinal tractInjury, poisoning and procedural complications | 1/70 | 0/71 |
| Event | Placebo | TAK-935 |
|---|---|---|
| Upper respiratory tract infectionInfections and infestations | 10/70 | 12/71 |
| PyrexiaGeneral disorders | 8/70 | 11/71 |
| SeizureNervous system disorders | 7/70 | 4/71 |
| NasopharyngitisInfections and infestations | 6/70 | 6/71 |
| SomnolenceNervous system disorders | 3/70 | 6/71 |
| VomitingGastrointestinal disorders | 4/70 | 6/71 |
| Decreased appetiteMetabolism and nutrition disorders | 5/70 | 6/71 |
| DiarrhoeaGastrointestinal disorders | 4/70 | 5/71 |
| LethargyNervous system disorders | 0/70 | 5/71 |
| InfluenzaInfections and infestations | 4/70 | 2/71 |
Randomized Analysis Set included all participants who were randomized into the study.
| Age, Continuous(years) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Mean | 9.5 ± 3.93 | 9.6 ± 4.14 | 9.5 ± 4.02 |
| Sex: Female, Male(Participants) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Female | 28 | 22 | 50 |
| Male | 42 | 49 | 91 |
| Ethnicity (NIH/OMB)(Participants) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Hispanic or Latino | 10 | 11 | 21 |
| Not Hispanic or Latino | 60 | 60 | 120 |
| Unknown or Not Reported | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | Placebo | TAK-935 | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 22 | 22 | 44 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 1 | 0 | 1 |
| White | 47 | 49 | 96 |
| More than one race | 0 | 0 | 0 |
| Unknown or Not Reported | 0 | 0 | 0 |
| Region of Enrollment(Participants) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Australia | 2 | 2 | 4 |
| Canada | 3 | 3 | 6 |
| China | 20 | 21 | 41 |
| Spain | 11 | 8 | 19 |
| Israel | 5 | 4 | 9 |
| Poland | 12 | 17 | 29 |
| Portugal | 2 | 3 | 5 |
| United States | 15 | 13 | 28 |
| Height(cm) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Mean | 132.4 ± 20.34 | 134.7 ± 21.34 | 133.6 ± 20.81 |
| Weight(kg) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Mean | 32.8 ± 15.98 | 33.3 ± 15.11 | 33.0 ± 15.49 |
| Body Mass Index (BMI)((kg/m^2)) | Placebo | TAK-935 | Total |
|---|---|---|---|
| Mean | 17.63 ± 4.378 | 17.43 ± 4.048 | 17.53 ± 4.198 |
1 further baseline measures are reported on the registry.
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form, Clinical study report
Access criteria: IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/. For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.
Data sharing details ↗ · vivli.org
This study is completed, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Soticlestat