Soticlestat in Rare Epilepsies CDKL5 Deficiency and Dup15q Syndrome Phase 2 Clinical Trials

In the ARCADE (NCT03694275) and ENDYMION (NCT03635073) studies of soticlestat (OV935/TAK-935, Ovid Therapeutics, New York, NY) seizure frequency in individuals with CDKL5 deficiency disorder (CDD) and Dup15q syndrome (Dup15q) decreased.

The combined data from ARCADE and ENDYMION studies show seizure frequency reduction occurred with soticlestat treatment over time. In the ARCADE study, participants with CDD (n=12), had a 24% average motor seizure frequency reduction during the 12-week maintenance period. The 5 participants with CDD who participated in a full 9 months of continuous treatment in the ENDYMION open-label extension achieved a and additions 12% reduction, for a total 36% fewer motor seizures compared to baseline. Although participants with Dup15q (n=8) had an increase in average motor seizure frequency during the 12-week maintenance periodthe 4 participants with Dup15q at 9 months of continuous treatment had a 74% reduction in average motor seizure frequency. Soticlestat continues to be well tolerated in both studies. 

ARCADE is a phase 2 open-label signal-finding pilot study designed to inform the potential for future development of soticlestat in CDD and Dup15q. The study enrolled 20 participants, ages 2 years to 55 years, with refractory epileptic seizures associated with CDD (n=12) or Dup15q (n=8). Study design included a 4- to 6-week screening period to establish baseline seizure frequency, followed by a 20-week treatment period, including an 8-week titration/dose optimization period and a 12-week maintenance period. Participants in the study were allowed to be on 1 to 6 concomitant antiseizure medications (ASMs), with the majority of participants concomitantly treated with at least 4 ASMs. 

ENDYMION is a multi-center open-label extension of up to 9 months for any participant (n=175) who has participated in any previous soticlestat clinical study, including participants with CDD, Dup15q, Dravet syndrome (DS) and Lennox-Gastaut syndrome. The ENDYMION study is meant to assess the long-term safety and tolerability of soticlestat in participants with rare epilepsies and, secondarily, to evaluate the effect of soticlestat on seizure control over time.

The most common adverse events were constipation (n=4/20, 20%), rash (n=3/20, 15%) and seizure (n=3/20, 15%). There were no serious adverse events considered related soticlestat or deaths reported.