Marinus Pharmaceuticals, a specialty pharmaceutical company, has met its primary endpoint for its Phase II clinical trial investigating the safety and efficacy of ganaxolone as adjunctive therapy in adults with partial onset seizures.
In this trial, ganaxolone demonstrated a statistically significant reduction in seizures versus placebo. Efficacy was seen in the first week of dosing. Ganaxolone was also found to be safe and well-tolerated in this population adding to the safety database of more than 950 subjects.
The Phase II trial was a randomized, double-blind, placebo-controlled trial evaluating ganaxolone as add-on therapy for adults with partial onset seizures, who continued to have seizures even while taking up to three antiepileptic drugs (AED). The trial enrolled 147 patients at 24 sites in the US.
Patients were observed for baseline seizure activity for 8 weeks and were then randomized to receive either ganaxolone or placebo in addition to their existing stable AED regimen. Patients entering the trial were experiencing, on average, eight to 11 seizures per month.
Patients randomized to the ganaxolone treatment arm were titrated over one to two weeks to a maintenance dose of 1,500mg/day where they were maintained for an additional eight weeks. Patients in the ganaxolone arm met the primary endpoint showing a statistically significant reduction of mean weekly seizure frequency versus the placebo arm during the titration and maintenance period (P<0.0251).
In addition, the patients in the ganaxolone arm also showed an improvement on percent reduction in seizure frequency versus placebo (P<0.0144). Responder rates were numerically larger in the ganaxolone arm versus placebo but did not reach statistical significance in this study (P<0.1926). Ganaxolone was generally well tolerated with the majority of patients able to escalate and maintain the 1500mg/day dose, the company said.
All patients completing the double blind portion were eligible to enter an open label extension trial, with 95% of patients electing to continue therapy. Based on these results, Marinus is planning a dose-ranging Phase IIb program with ganaxolone.