The small molecule simufilam dose‐dependently attenuates the worsening of seizures in a mouse model of tuberous sclerosis complex

OBJECTIVE: Novel epilepsy treatments for patients with tuberous sclerosis complex (TSC) and focal cortical dysplasia type II (FCDII) are urgently needed. In these patients, mutations in the mechanistic target of rapamycin (mTOR) pathway genes lead to mTOR hyperactivity and focal cortical malformations that frequently cause intractable epilepsy and neurological sequelae. Recent evidence suggests that administration of simufilam, a small molecule thought to modulate the function of filamin A, reduces seizure activity independent of mTOR in a mouse model of FCDII. Here, we tested the hypothesis that simufilam treatment reduces seizure activity in a TSC mouse model and characterized its pharmacokinetic (PK) profile in wild-type mice. METHODS: Seizure activity was recorded via electroencephalography (EEG) in juvenile Tsc1 conditional knockout (cKO) mice treated with simufilam or vehicle twice daily (BID). Simufilam plasma concentrations were measured at study termination using liquid chromatography-tandem mass spectrometry. PK analysis was performed in CD1 mice following daily administration of simufilam for 1 or 7 days at two different doses. RESULTS: Vehicle- and 5 mg/kg-treated Tsc1 cKO mice showed a significant increase in seizure frequency and total ictal duration between the first and the last 5 days of EEG monitoring (Wilcoxon signed-rank test, p < .05), whereas the 10- and 20-mg/kg-treated groups did not. In addition, simufilam treatment shifted the distribution of total ictal durations, with fewer mice exhibiting total ictal durations above the median of the vehicle-treated group (Fisher's exact test, p = .021). Increasing simufilam dose and plasma concentration were associated with fewer daily seizures recorded during the last 5 days of EEG monitoring (p = .017 and p = .012, respectively). Every 100 ng/mL increase in plasma concentration corresponded to a decrease of ~.2 seizures per day during the last 5-day period. SIGNIFICANCE: These findings suggest that simufilam treatment in a TSC mouse model prevented the worsening of seizure activity in a dose-dependent manner and supports clinical investigation of simufilam as a potential therapeutic intervention for seizures in TSC.