Trial Outcomes & Findings for A Study of Soticlestat as an Add-on Therapy in Children and Adults With Dravet Syndrome or Lennox-Gastaut Syndrome (NCT NCT05163314)

Participants took part in the study at various investigative sites globally from 04 March 2022 to 24 September 2025.

A total of 352 participants with Dravet Syndrome (DS) or Lennox-Gastaut Syndrome (LGS) who had participated in phase 3 clinical studies, TAK-935-3001 (NCT04940624), or TAK-935-3002 (NCT04938427), respectively, and who continued to receive standard-of-care (SOC) antiseizure therapy were enrolled in the study for added treatment with soticlestat.

Number analyzed is the number of participants with data available for analysis.

An Adverse Event (AE) was 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 was therefore 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 was considered related to the drug. A TEAE was defined as any AE that started or increased in severity after the first dose of the study drug in this open label extension (OLE) study.

C-SSRS systematically tracks suicidal ideation and behavior. Responses to questions in the C-SSRS at baseline and each post-baseline time point were collected for participants ≥6 years of age. C-SSRS incidences were categorized as follows: No Suicidal Ideation or Suicidal Behavior or Non-suicidal Self-injurious Behavior (No SI or SB or NSSJB), Non-suicidal Self-injurious Behavior (NSSJB), Suicidal Ideation (SI), and Suicidal Behavior (SB). For each visit (V), the "Yes" answer to the question with the highest severity rank was used to determine the C-SSRS category of a participant. The category Missing indicates the number of participants for whom no data was collected at the particular time point. For each time point only categories with at least 1 participant are presented. BL denotes Baseline and W denotes Week for the reported categories.

BL denotes Baseline, CFB denotes Change from Baseline and W denotes Week for the reported categories.

BL denotes Baseline, CFB denotes Change from Baseline and W denotes Week for the reported categories.

Tanner assessment scores were 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) by age (6 to 17 years of age) and sex (boys and girls) during the study. Tanner scale boy clinical classification test names for each stage are reported as follows: TANN02-Genitalia and TANN02-Pubic Hair. Tanner scale girl clinical classification test names for each stage are reported as follows: TANN01-Breast and TANN01-Pubic Hair.

Absolute values of IGF1 were summarized descriptively as a continuous variable by age and by sex (male and female). If multiple assessments for a participant at different visits at a particular age were available, then the average of all data for that participant were used for the summary.

Seizure frequency per 28 days was 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 was 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.

Convulsive seizure frequency per 28 days was 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 was 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.

MMD seizure frequency per 28 days was defined as the total number of MMD seizures reported during the period divided by the number of days during the period seizures were assessed multiplied by 28. Percent change from baseline was 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.

The CGI-I Clinician is a 7-point Likert scale that the investigator uses to rate a participant's change in overall seizure control, behavior, safety and tolerability, after the initiation of study drug relative to Baseline (before treatment with study drug). The participants were 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). Reported here is the number of participants with improvement, which includes the CGI-I responses: very much improved, much improved, minimally improved.

The Care GI-I is a 7-point Likert scale that the caregiver used to rate a participant's change in overall seizure control, behavior, safety and tolerability after the initiation of study drug relative to Baseline (before treatment with study drug). The participants were 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 completed the Care GI-I via interview. Reported here is the number of participants with improvement, which includes the Care GI-I responses: very much improved, much improved, minimally improved.

The CGI-I seizure intensity and duration instrument was used by the parent/caregiver to rate a participant's change in intensity and duration of convulsive seizures (DS Cohort) or MMD seizures (LGS Cohort) from Baseline. The participant's symptoms were 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). Reported here is the number of participants with improvement, which includes the CGI-I Seizure responses: very much improved, much improved, minimally improved.

The CGI-I nonseizure symptoms instrument is a series of single-item assessments that the investigator used to rate a participant's change in the caregiver-identified symptoms and impacts in select nonseizure domains since initiating the study drug. The participants were 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 was completed by the clinician in collaboration with the primary caregiver to assess the participants status based on the presence of any nonseizure symptoms. Reported here is the number of participants with improvement, which includes the CGI-I nonseizure symptoms responses: very much improved, much improved, minimally improved.

The 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. Items were rated on a 5-point Likert scale and then transformed to a scale of 0 to 100. Possible scores range from 0-100, with higher scores indicating better quality of life. Negative change from baseline indicates worsening of quality of life.