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CompletedNCT03166215Updated Sep 14, 2026Results posted

Study of TAK-935 as an Adjunctive Therapy in Participants With Developmental and/or Epileptic Encephalopathies

A Phase 1/2 interventional study of TAK-935 and Placebo in Developmental and/or Epileptic Encephalopathies, sponsored by Takeda. Completed at 11 sites in United States. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-09-14.

Sponsored by Takeda · Phase 1/2, Interventional, and Treatment

Phase
Phase 1/2
Study type
Interventional
Enrollment
18
Allocation
Randomized
Ages
18 Years to 65 Years
Sex
All
01

Study summary

The purpose of this study is to characterize the multiple-dose safety and tolerability profile of TAK-935 in adult participants with developmental and/or epileptic encephalopathies.

Read the detailed description

The drug being tested in this study is called TAK-935. TAK-935 is being tested to treat people who have developmental and/or epileptic encephalopathies. This study will look at safety, tolerability and pharmacokinetics of people who take TAK-935. Study drug will be administered in a double-blind manner in Part 1 and in an open-label manner in Part 2.

The study will enroll approximately 20 participants. Participants will be randomly assigned (by chance, like flipping a coin) to one of the two treatment groups in Part 1-which will remain undisclosed to the participant and study doctor during the study (unless there is an urgent medical need):

  • TAK-935
  • Placebo (dummy inactive pill) - this is a tablet that looks like the study drug but has no active ingredient

Participants will receive placebo or 100 milligram (mg) TAK-935 tablets, orally or through stable G-tube/PEG tube, BID, in Part 1 (Day 1) and dose will be increased to 200 mg (Day 11) BID and to 300 mg (Day 21) BID in dose titration period. All participants who complete the Double-Blind Treatment Period in Part 1 will have the option to continue directly into the Open-Label Treatment Period in Part 2 where they will receive TAK-935 as two 100 mg tablets (total dose is 200 mg TAK-935) orally or through G-tube/PEG tube, BID and dose will be increased to three 100 mg tablets (total dose is 300 mg TAK-935), orally, BID (Day 41). This dose level will be maintained until the final visit (Day 85) for the dose de-escalation phase.

This multi-center trial will be conducted in North America. The overall time to participate in this study is 121 days excluding screening period of 30-41 days. Participants will make multiple visits to the clinic, and a follow-up phone call will be conducted on Day 91 and at the end of the 30-day follow-up period (Day 121), participants will return to the clinic for a follow-up assessment.

02

Conditions studied

  • Developmental and/or Epileptic Encephalopathies

Keywords

  • Drug therapy
03

In context

Lead sponsor

Takeda is the lead sponsor of 1,002 studies on the registry; 92 are open to participants now.

Of its 173 completed or terminated interventional studies of FDA-regulated products, 149 (86%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 65 Years
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

  1. Has a documented clinical diagnosis of developmental and/or epileptic encephalopathies with countable bilateral motor seizures, defined as an average of greater than or equal to (>=) 2 per month during the past 3 months, based on the investigator's assessment, and a monthly average of >=1 per month during the Baseline Period, based on the seizure diary record.
  2. Has been taking 1 to 4 antiepileptic drug (AEDs) at a stable dose for >=4 weeks before Screening and the participant or participant's legally acceptable representative is willing to keep the regimen(s) stable throughout the study.
  3. Has an average of >=1 bilateral motor seizure per month during the 4-week Baseline Period (that is., drop seizures, tonic-clonic, tonic, bilateral clonic, atonic, myoclonic-atonic, myoclonic-tonic-clonic, focal seizures with bilateral hyperkinetic motor features).
  4. Must agree to not post any participant's personal medical data related to the study or information related to the study on any web site or social media site (example, Facebook, Twitter) until the study has been completed.
  5. For participants with G-tube/PEG tube, G-tubes/PEG tubes should have been placed and been functioning for at least 3 months prior to screening. Naso-gastric tubes are not allowed.

Exclusion criteria

Exclusion Criteria:

  1. Has received TAK-935 in a previous clinical study or as a therapeutic agent.
  2. Was admitted to a medical facility for treatment of status epilepticus requiring mechanical respiration within 3 months before Screening.
  3. Had a vagal nerve stimulator implanted within 6 months before Screening and settings have been changed within 1 month of the Screening Visit and/or anticipated to change during the study.
  4. Is on ketogenic diet that has been started within 6 months of the Screening Visit, has been changed within 1 month of the Screening Visit, or is anticipated to change during the study.
  5. Has degenerative eye disease.
  6. Has a history of suicidal behavior or any suicidal ideation of type 4 or 5 on the Columbia-Suicide Severity Rating Scale (C-SSRS) at Screening. If the participant is unable to comply with the C-SSRS due to developmental status, a parent proxy may be used for the completion of the C-SSRS. The Investigator may also use clinical judgment, which must then be documented in the source document.
  7. Positive for human immunodeficiency virus, hepatitis B, or hepatitis C infections. (Note that participants who have been vaccinated against hepatitis B [hepatitis B surface antibody (Ab)-positive] who are negative for other markers of prior hepatitis B infection [example, negative for hepatitis B core Ab] are eligible. Also note that participants who are positive for hepatitis C Ab are eligible as long as they have a negative hepatitis C viral load by quantitative polymerase chain reaction [qPCR]).
  8. Has an abnormal and clinically significant ECG at Screening in the opinion of the investigator, for example, second or third degree heart block or a corrected QT interval (QTc) greater than (>) 450 millisecond (msec). Entry of any participant with an abnormal but not clinically significant ECG must be approved and documented by signature by the principal investigator or appropriately qualified delegate.
  9. Has abnormal clinical laboratory test results at Screening that suggest a clinically significant underlying disease. If the participant has alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) >2.5*the upper limit of normal (ULN), the Medical Monitor should be consulted.
  10. Has received any excluded medications, procedures, or treatments during the time periods.
  11. Has any a history of alcohol, opioid, or other drug use disorder, as per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, within the previous 2 years before Screening. Medical marijuana use is allowed.
  12. Has unstable, clinically significant neurologic (other than the disease being studied), psychiatric, cardiovascular, pulmonary, hepatic, renal, metabolic, gastrointestinal, urologic, immunologic, hematopoietic, or endocrine disease or other abnormality, which may impact the ability of the participant to participate or potentially confound the study results.
05

Study design

Phase
Phase 1 / Phase 2
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Quadruple (Participant, Care provider, Investigator, Outcomes assessor)
Enrollment
18 participants (actual)

Study arms

  • Placebo comparator
    Part 1: Placebo

    TAK-935 matching-placebo tablets, orally or through gastrostomy tube (G-tube)/ percutaneous endoscopic gastrostomy (PEG) tube, twice daily (BID) from Days 1 to 30 in dose titration period.

    Drug: TAK-935

  • Experimental
    Part 1: TAK-935

    TAK-935 100 mg, tablet, orally or through G-tube/PEG tube, BID from Days 1 to 10 followed by TAK-935 100 mg tablets x2, orally or through G-tube/PEG tube, BID from Days 11 to 20 followed by TAK-935 100 mg tablets x3, orally or through G-tube/PEG tube, BID from Days 21 to 30 in dose titration period. The dose of TAK-935 was escalated or de-escalated during Part 1 as per investigator's discretion.

    Drug: Placebo

  • Experimental
    Part 2: TAK-935

    TAK-935 100 mg tablets x2, orally or through G-tube/PEG tube, BID from Days 31 to 40 followed by TAK-935 100 mg tablets x1, x2 or x3, orally or through G-tube/PEG tube, BID from Days 31 to Day 85 as per investigator's discretion in the maintenance period. At the end of Part 2, the dose of TAK-935 was de-escalated until discontinuation.

    Drug: TAK-935

Interventions

  • DrugTAK-935

    TAK-935 tablets.

  • DrugPlacebo

    TAK-935 placebo-matching tablets.

06

What researchers measure

Primary outcomes

  1. Percentage of Participants With at Least One Treatment-Emergent Adverse Event (TEAE), as Reported by the Participants or Participant's Caregivers or Observed by the Investigator, After TAK-935 Treatment

    An 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 (eg, 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 treatment-emergent adverse event (TEAE) is defined as an adverse event with an onset that occurs after receiving study drug

    Time frame: From first dose up to 30 days post last dose (approximately up to 120 days)

Secondary outcomes

  1. Drug Clearance (CL) and Intercompartmental Clearance (Q) for TAK-935 Calculated Using the Observed Value of the Last Quantifiable Concentration

    Time frame: Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose

  2. Apparent Volume of Distribution (Vz/F) of Central Compartment (Vc) and Peripheral Compartment (Vp) for TAK-935 Calculated Using the Observed Value of the Last Quantifiable Concentration

    Time frame: Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose

  3. Absorption Rate Constant (Ka) for TAK-935

    Time frame: Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose

  4. Cmax,ss: Maximum Observed Plasma Concentration for TAK-935 at Steady State

    Time frame: Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose

  5. AUC0-tau,ss: Area Under the Plasma Concentration-time Curve Over the Dosing Interval for TAK-935 at Steady State

    Time frame: Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose

  6. Cav,ss: Average Plasma Concentration During a Dosing Interval at Steady State for TAK-935

    Time frame: Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose

  7. Ctrough,ss: Plasma Concentration Immediately Prior to Dosing for TAK-935 at Steady State

    Time frame: Days 1, 11, 21; Days 31, 41 and 85 pre-dose

  8. Percentage of Participants With at Least 1 Markedly Abnormal Value for Clinical Laboratory Evaluations After TAK-935

    Clinical Laboratory parameters: hematology, serum chemistry and urinalysis. Participants with at least 1 markedly abnormal values during treatment period were reported: Erythrocytes: \<0.8xLLN-\>1.5xULN, Hematocrit: \<0.8x LLN \>1.2xULN,Hemoglobin: \<0.8xLLN-\>1.2xULN Leukocytes: \<0.5xLLN, Platelets (10\^9/L): \<75x10\^9/L-\>600x10\^9/L, Prothrombin Ratio: \>1.5xULN, Alanine Aminotransferase: \>3xULN, Albumin:\<25 g/L, Alkaline Phosphatase: \>3xULN,Alpha-1 Acid Glycoprotein: \<47 mg/DL-\>125 mg/DL, Aspartate Aminotransferase:\>3xULN, Bicarbonate:\<8.0 mmol/L, Calcium:\<1.75 mmol/L-\>2.88 mmol/L, Chloride:\<75 mmol/L-\>126 mmol/L, Cholesterol: \>7.72,Creatine Kinase:\>5xULN, Creatinine:\>177 umol/L, Gamma Glutamyl Transferase: \>3xULN, Glucose:\<2.8 mmol/L- \>19.4 mmol/L,HDL Cholesterol: \<1.04 mmol/L-\>1.55 mmol/L, LDL Cholesterol: \<1.30 mmol/L-\>4.14 mmol/L, Potassium:\<3.0 mmol/L-\>6.0 mEq/L, Protein:\<0.8xLLN-\>1.2 x ULN, Sodium: \<130 mmol/L-\>150 mmol/L, Triglycerides: \>2.5xULN, Urea Nitrogen: \>10.7 mmol/L.

    Time frame: From first dose up to last dose (up to Day 85)

  9. Percentage of Participants With at Least 1 Markedly Abnormal Value for Vital Signs After TAK-935

    Vital signs included heart rate, blood pressure and body temperature. markedly abnormal values during treatment period were categorized as: heart rate 1,3 and 5 min standing (beats/min) \<50-\>120, systolic blood pressure 1,3 and 5 min standing (mmHg) \<85-\>180, diastolic blood pressure 1,3 and 5 min standing (mmHg) \<50-\>110 and body temperature (degree centigrade) \<35.6- \>37.7. Only categories with values have been reported.

    Time frame: From first dose up to 30 days post last dose (approximately up 120 days)

  10. Percentage of Participants With at Least 1 Markedly Abnormal Value for Electrocardiogram (ECG) Parameters After TAK-935

    A 12-lead ECG was performed. Markedly abnormal values during treatment period were categorized as: ECG ventricular rate \<50-\>120, PR Interval, (msec) \<=80-\>=200, QRS Duration, (msec) \<=80-\>=180, QT Interval, (msec) \<=50-\>=460, QTcF Interval, (msec) \<=50-\>=500 OR \>=30 change from baseline and \>=450 milliseconds, RR interval \<600-\>=1440.

    Time frame: From first dose up to last dose (up to Day 85)

07

Results

Posted Jan 10, 2020

Participant flow

Participants took part in the study at 10 investigative sites in the United States from 17 August 2017 to 19 September 2018.

Part 1 (Double-blind TP: Days 1 - 30)
Participant flow — Part 1 (Double-blind TP: Days 1 - 30)
MilestonePart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Started4140
Completed4120
Not completed020
Withdrew: Adverse event020
Part 2 (Open-Label TP: Days 31 - 85)
Participant flow — Part 2 (Open-Label TP: Days 31 - 85)
MilestonePart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Started0016
Completed0014
Not completed002
Withdrew: Adverse event002

Outcome measures

PrimaryPercentage of Participants With at Least One Treatment-Emergent Adverse Event (TEAE), as Reported by the Participants or Participant's Caregivers or Observed by the Investigator, After TAK-935 Treatment

An 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 (eg, 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 treatment-emergent adverse event (TEAE) is defined as an adverse event with an onset that occurs after receiving study drug

Time frame:
From first dose up to 30 days post last dose (approximately up to 120 days)
Reported as:
Number · percentage of participants
Percentage of Participants With at Least One Treatment-Emergent Adverse Event (TEAE), as Reported by the Participants or Participant's Caregivers or Observed by the Investigator, After TAK-935 Treatment
percentage of participantsPart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Percentage of Participants With at Least One Treatment-Emergent Adverse Event (TEAE), as Reported by the Participants or Participant's Caregivers or Observed by the Investigator, After TAK-935 Treatment10071.468.8
SecondaryDrug Clearance (CL) and Intercompartmental Clearance (Q) for TAK-935 Calculated Using the Observed Value of the Last Quantifiable Concentration
Time frame:
Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose
Reported as:
Mean · L/hr
Drug Clearance (CL) and Intercompartmental Clearance (Q) for TAK-935 Calculated Using the Observed Value of the Last Quantifiable Concentration
L/hrTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
CL259.4 ± 148.1195.8 ± 116.3190 ± 108.5
Q100.6 ± 22.2470.99 ± 14.657.77 ± 11.36
SecondaryApparent Volume of Distribution (Vz/F) of Central Compartment (Vc) and Peripheral Compartment (Vp) for TAK-935 Calculated Using the Observed Value of the Last Quantifiable Concentration
Time frame:
Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose
Reported as:
Mean · L
Apparent Volume of Distribution (Vz/F) of Central Compartment (Vc) and Peripheral Compartment (Vp) for TAK-935 Calculated Using the Observed Value of the Last Quantifiable Concentration
LTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
Vc56.59 ± 22.7260.51 ± 23.7962 ± 26.54
Vp677.1 ± 296.2474.3 ± 201.9352.9 ± 138.7
SecondaryAbsorption Rate Constant (Ka) for TAK-935
Time frame:
Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose
Reported as:
Mean · 1/hr
Absorption Rate Constant (Ka) for TAK-935
1/hrTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
Absorption Rate Constant (Ka) for TAK-9352.13 ± 02.13 ± 02.13 ± 0
SecondaryCmax,ss: Maximum Observed Plasma Concentration for TAK-935 at Steady State
Time frame:
Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose
Reported as:
Mean · ng/mL
Cmax,ss: Maximum Observed Plasma Concentration for TAK-935 at Steady State
ng/mLTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
Cmax,ss: Maximum Observed Plasma Concentration for TAK-935 at Steady State269.6 ± 159.6639.8 ± 354.8975.3 ± 411.5
SecondaryAUC0-tau,ss: Area Under the Plasma Concentration-time Curve Over the Dosing Interval for TAK-935 at Steady State
Time frame:
Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose
Reported as:
Mean · ng*hr/mL
AUC0-tau,ss: Area Under the Plasma Concentration-time Curve Over the Dosing Interval for TAK-935 at Steady State
ng*hr/mLTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
AUC0-tau,ss: Area Under the Plasma Concentration-time Curve Over the Dosing Interval for TAK-935 at Steady State562.5 ± 406.81437 ± 9092188 ± 1357
SecondaryCav,ss: Average Plasma Concentration During a Dosing Interval at Steady State for TAK-935
Time frame:
Day 1 pre-dose and at multiple timepoints (up to 5 hours) post-dose; Days 11 and 21 pre-dose and 1-hour post-dose; Days 31, 41, and 85 pre-dose
Reported as:
Mean · ng/mL
Cav,ss: Average Plasma Concentration During a Dosing Interval at Steady State for TAK-935
ng/mLTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
Cav,ss: Average Plasma Concentration During a Dosing Interval at Steady State for TAK-93546.9 ± 33.9119.8 ± 75.75182.3 ± 113.1
SecondaryCtrough,ss: Plasma Concentration Immediately Prior to Dosing for TAK-935 at Steady State
Time frame:
Days 1, 11, 21; Days 31, 41 and 85 pre-dose
Reported as:
Mean · ng/mL
Ctrough,ss: Plasma Concentration Immediately Prior to Dosing for TAK-935 at Steady State
ng/mLTAK-935 100 mg BIDTAK-935 200 mg BIDTAK-935 300 mg BID
Ctrough,ss: Plasma Concentration Immediately Prior to Dosing for TAK-935 at Steady State10.5 ± 13.8326 ± 29.230.2 ± 29.12
SecondaryPercentage of Participants With at Least 1 Markedly Abnormal Value for Clinical Laboratory Evaluations After TAK-935

Clinical Laboratory parameters: hematology, serum chemistry and urinalysis. Participants with at least 1 markedly abnormal values during treatment period were reported: Erythrocytes: \<0.8xLLN-\>1.5xULN, Hematocrit: \<0.8x LLN \>1.2xULN,Hemoglobin: \<0.8xLLN-\>1.2xULN Leukocytes: \<0.5xLLN, Platelets (10\^9/L): \<75x10\^9/L-\>600x10\^9/L, Prothrombin Ratio: \>1.5xULN, Alanine Aminotransferase: \>3xULN, Albumin:\<25 g/L, Alkaline Phosphatase: \>3xULN,Alpha-1 Acid Glycoprotein: \<47 mg/DL-\>125 mg/DL, Aspartate Aminotransferase:\>3xULN, Bicarbonate:\<8.0 mmol/L, Calcium:\<1.75 mmol/L-\>2.88 mmol/L, Chloride:\<75 mmol/L-\>126 mmol/L, Cholesterol: \>7.72,Creatine Kinase:\>5xULN, Creatinine:\>177 umol/L, Gamma Glutamyl Transferase: \>3xULN, Glucose:\<2.8 mmol/L- \>19.4 mmol/L,HDL Cholesterol: \<1.04 mmol/L-\>1.55 mmol/L, LDL Cholesterol: \<1.30 mmol/L-\>4.14 mmol/L, Potassium:\<3.0 mmol/L-\>6.0 mEq/L, Protein:\<0.8xLLN-\>1.2 x ULN, Sodium: \<130 mmol/L-\>150 mmol/L, Triglycerides: \>2.5xULN, Urea Nitrogen: \>10.7 mmol/L.

Time frame:
From first dose up to last dose (up to Day 85)
Reported as:
Number · percentage of participants
Percentage of Participants With at Least 1 Markedly Abnormal Value for Clinical Laboratory Evaluations After TAK-935
percentage of participantsPart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Alpha-1 Acid Glycoprotein (>125 mg/DL)011.114.3
Gamma Glutamyl Transferase ( >3 x ULN)09.16.7
HDL Cholesterol (<1.04 mmol/L)75.018.240.0
HDL Cholesterol (>1.55 mmol/L)027.313.3
LDL Cholesterol (>4.14 mmol/L)09.10
Potassium (>6.0 mmol/L)09.10
SecondaryPercentage of Participants With at Least 1 Markedly Abnormal Value for Vital Signs After TAK-935

Vital signs included heart rate, blood pressure and body temperature. markedly abnormal values during treatment period were categorized as: heart rate 1,3 and 5 min standing (beats/min) \<50-\>120, systolic blood pressure 1,3 and 5 min standing (mmHg) \<85-\>180, diastolic blood pressure 1,3 and 5 min standing (mmHg) \<50-\>110 and body temperature (degree centigrade) \<35.6- \>37.7. Only categories with values have been reported.

Time frame:
From first dose up to 30 days post last dose (approximately up 120 days)
Reported as:
Number · percentage of participants
Percentage of Participants With at Least 1 Markedly Abnormal Value for Vital Signs After TAK-935
percentage of participantsPart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Diastolic Blood Pressure 3 min Standing (<50 mmHg)33.300
Diastolic Blood Pressure 5 min Sitting (<50 mmHg)07.10
Diastolic Blood Pressure 5 min Supine (<50 mmHg)25.000
Heart Rate 1 min Standing (>120 beats/min)016.70
Heart Rate 5 min Sitting (<50 beats/min)50.006.3
Heart Rate 5 min Supine (<50 beats/min)25.000
Systolic Blood Pressure 5 min Sitting (<85 mmHg)07.10
Temperature (<35.6 C)25.07.718.8
SecondaryPercentage of Participants With at Least 1 Markedly Abnormal Value for Electrocardiogram (ECG) Parameters After TAK-935

A 12-lead ECG was performed. Markedly abnormal values during treatment period were categorized as: ECG ventricular rate \<50-\>120, PR Interval, (msec) \<=80-\>=200, QRS Duration, (msec) \<=80-\>=180, QT Interval, (msec) \<=50-\>=460, QTcF Interval, (msec) \<=50-\>=500 OR \>=30 change from baseline and \>=450 milliseconds, RR interval \<600-\>=1440.

Time frame:
From first dose up to last dose (up to Day 85)
Reported as:
Number · percentage of participants
Percentage of Participants With at Least 1 Markedly Abnormal Value for Electrocardiogram (ECG) Parameters After TAK-935
percentage of participantsPart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
ECG Ventricular Rate (<50 beats/min)33.300
QRS Duration (<=80 msec)012.56.7
RR Interval (<=600 msec)0013.3

Adverse events

Collected over From first dose up to 30 days post last dose (approximately up to 120 days). Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Part 1: Placebo0/4 (0%)0/4 (0%)4/4 (100%)
Part 1: TAK-9350/14 (0%)1/14 (7.1%)10/14 (71.4%)
Part 2: TAK-9350/16 (0%)3/16 (18.8%)11/16 (68.8%)
Most frequent serious events
Most frequent serious events
EventPart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Seizure ClusterNervous system disorders0/41/142/16
SeizureNervous system disorders0/40/141/16
Most frequent other events
Showing 10 of 48
Most frequent other events
EventPart 1: PlaceboPart 1: TAK-935Part 2: TAK-935
Sleep talkingPsychiatric disorders1/40/140/16
HeadacheNervous system disorders1/42/140/16
SedationNervous system disorders1/40/140/16
Tonic convulsionNervous system disorders1/40/140/16
VomitingGastrointestinal disorders1/41/141/16
ConstipationGastrointestinal disorders1/40/140/16
RashSkin and subcutaneous tissue disorders1/40/141/16
HyperhidrosisSkin and subcutaneous tissue disorders1/40/140/16
Urinary incontinenceRenal and urinary disorders1/41/140/16
FatigueGeneral disorders1/42/140/16

Baseline characteristics

Randomized set included all participants who were randomly assigned to treatment through the interactive voice response system/ interactive web response system (IVRS/IWRS).

Age, Continuous
Age, Continuous(years)Part 1: PlaceboPart 1: TAK-935Total
Mean27.8 ± 8.3829.4 ± 7.8329.1 ± 7.73
Sex: Female, Male
Sex: Female, Male(Participants)Part 1: PlaceboPart 1: TAK-935Total
Female044
Male41014
Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)Part 1: PlaceboPart 1: TAK-935Total
Hispanic or Latino022
Not Hispanic or Latino41216
Unknown or Not Reported000
Race (NIH/OMB)
Race (NIH/OMB)(Participants)Part 1: PlaceboPart 1: TAK-935Total
American Indian or Alaska Native000
Asian000
Native Hawaiian or Other Pacific Islander000
Black or African American101
White31316
More than one race000
Unknown or Not Reported011
Region of Enrollment
Region of Enrollment(Participants)Part 1: PlaceboPart 1: TAK-935Total
United States41418
Height
Height(cm)Part 1: PlaceboPart 1: TAK-935Total
Mean170.78 ± 14.115163.80 ± 9.746165.35 ± 10.802
Weight
Weight(kg)Part 1: PlaceboPart 1: TAK-935Total
Mean86.35 ± 26.65168.57 ± 21.70272.52 ± 23.310
Body Mass Index (BMI)
Body Mass Index (BMI)(kg/m^2)Part 1: PlaceboPart 1: TAK-935Total
Mean29.08 ± 5.68824.61 ± 6.63925.61 ± 6.562

1 further baseline measures are reported on the registry.

08

Study locations

11 sites
  • Xenoscience
    Phoenix, Arizona 85004, United States
  • Medsol Clinical Research Center
    Port Charlotte, Florida 33952, United States
  • University of South Florida
    Tampa, Florida 33606, United States
  • Center for Integrative Rare Disease Research
    Atlanta, Georgia 30318, United States
  • Bluegrass Epilepsy Research
    Lexington, Kentucky 40504, United States
  • Mid-Atlantic Epilepsy and Sleep Center
    Bethesda, Maryland 20817, United States
  • The Comprehensive Epilepsy Care Center for Children and Adults
    St Louis, Missouri 63131, United States
  • Northeast Regional Epilepsy Group
    Hackensack, New Jersey 07601, United States
  • Thomas Jefferson University
    Philadelphia, Pennsylvania 19107, United States
  • Medical University of South Carolina
    Charleston, South Carolina 29425, United States
  • University of Virginia Health Sciences Center
    Charlottesville, Virginia 22903, United States
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References and documents

Publications

  • Halford JJ, Sperling MR, Arkilo D, Asgharnejad M, Zinger C, Xu R, During M, French JA. A phase 1b/2a study of soticlestat as adjunctive therapy in participants with developmental and/or epileptic encephalopathies. Epilepsy Res. 2021 Aug;174:106646. doi: 10.1016/j.eplepsyres.2021.106646. Epub 2021 Apr 22. PubMed 33940389 ↗

Study documents

  • Study protocol · Mar 21, 2018
  • Statistical analysis plan · Oct 26, 2018

Documents are hosted by the registry — open the source record to download them.

Individual participant data

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, Sap, Icf, Csr

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Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Sep 14, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
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Registry details

Key details

Study ID
NCT03166215
Lead sponsor
Takeda
Collaborators
Healx AI
Responsible party
Sponsor
First posted
May 25, 2017
Start date
Aug 17, 2017
Primary completion
Sep 19, 2018
Completion
Sep 19, 2018
Results posted
Jan 10, 2020
Last update
Sep 14, 2026

Study contacts

Medical Monitor Clinical Science
study director · Takeda (Note: This product was divested to Mistrau Bio, Inc. in 2026)

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.

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