A Study of Soticlestat in Adults and Children With Rare Epilepsies (Endymion 1)

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Status and phase

Active, not recruiting
Phase 2


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


Drug: Soticlestat

Study type


Funder types



U1111-1218-5515 (Other Identifier)
2018-002485-39 (EudraCT Number)
2022-502801-13 (Other Identifier)

Details and patient eligibility


The main aim is to assess the long-term safety and tolerability of soticlestat when used along with other anti-seizure treatment. Participants will receive soticlestat twice a day. Participants will visit the study clinic every 2-6 months throughout the study. Study treatments may continue as long as the participant is receiving benefit from it.

Full description

The drug being tested in this study is called soticlestat (TAK-935). This global, open-label extension (OLE) study will assess the long-term safety and tolerability of soticlestat in participants with developmental and epileptic encephalopathy (DEE) who participated in previous short-term efficacy/safety studies of soticlestat. All participants will receive Soticlestat treatment. Participants who rollover from previous blinded study will undergo up to 2 weeks of Dose Optimization Period (depending on the previous study) followed by Maintenance Period. Participants who rollover from an open-label study will continue on their current dose until development is stopped by the sponsor, or the product is approved for marketing, or at any time at the discretion of the sponsor. There will be a 4-week Safety Follow-up Period after the last dose in Maintenance Period, including a 2-week dose Tapering Period.


156 patients




2+ years old


No Healthy Volunteers

Inclusion criteria

Participants must have participated in a previous soticlestat study and meet one of the following conditions:

  • Successfully completed a soticlestat clinical study.
  • Received at least 10 weeks of treatment with the study drug in an antecedent placebo-controlled blinded soticlestat clinical study and the participant did not have a serious or severe AE that, in the investigator's or sponsor's opinion, was related to the study drug and would make it unsafe for the participant to continue receiving the study drug.
  • In the opinion of the investigator, the participant has the potential to benefit from the administration of soticlestat

Exclusion criteria

  • Clinically significant disease, that, in the investigator's opinion, precludes study participation.
  • Enrollment in any other clinical trial involving an investigational drug, device, or treatment in the past 90 days (with the exception of an antecedent study involving Soticlestat).
  • Participant is currently pregnant or breastfeeding or is planning to become pregnant during the study or within 30 days of the last study drug administration.
  • Suicide attempt within the last year, at significant risk of suicide (either in the opinion of the investigator or defined as 'yes' to suicidal ideation question 4 or 5 on the C-SSRS at Screening) or appearing suicidal per investigator judgment.

Trial design

Primary purpose




Interventional model

Single Group Assignment


None (Open label)

156 participants in 1 patient group

Experimental group
Treatment: Soticlestat, tablets orally twice daily at optimized dose, titrated in up to 2 weeks of Dose Optimization Period, followed by Maintenance Period, which lasts until development is stopped by the sponsor, or the product is approved for marketing, or at any time at the discretion of the sponsor.
Drug: Soticlestat

Trial contacts and locations



Data sourced from clinicaltrials.gov

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