Takeda Pharmaceutical and Ovid Therapeutics have announced positive Phase II trial results for their epilepsy drug soticlestat in children with the hard-to-treat epilepsy syndromes Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS).

While the trial ELEKTRA as a whole met the primary endpoint demonstrating a reduction in seizure frequency, soticlestat performed best in children with DS, with a 46.0% median placebo-adjusted reduction in seizure frequency. In comparison, in children with LGS, the median placebo-adjusted reduction in seizure frequency was 14.8%. As such, it is expected that moving forward the focus will be on Dravet syndrome, with a Phase III study in just this patient population expected. Although the results were not statistically significant when looking at just LGS, it could still be possible for the companies to move forward with this indication if further analysis of the trial data shows that soticlestat is effective for a subset of LGS patients, as it is a highly heterogeneous patient population.

Any drug being developed for DS or LGS will face the challenge of having to compete with GW Pharmaceuticals’ Epidiolex, which currently dominates the market. Not only does Epidiolex have the first-to-market advantage, but, as a cannabidiol-derived drug, it also has strong patient advocacy behind it, and GlobalData expects it to reach blockbuster status by 2022 with sales of $1.01B in the US. In future Phase III trials soticlestat has the potential to demonstrate more efficacy for Dravet syndrome than Epidiolex, which, if it does, would allow it to compete with Epidiolex.

As Dravet syndrome and LGS are generally treatment-resistant to typical antiepileptic drugs, more treatment options are needed, particularly for patients who do not respond to Epidiolex. Takeda and Ovid are also looking to develop soticlestat for other hard-to-treat epilepsy syndromes, with results from an open-label Phase II study in CDKL5 deficiency disorder and duplication 15q syndrome expected later this year. If soticlestat can be shown to still be effective in a larger Phase III trial, GlobalData expects global annual revenue of $667M by 2026.