Cambridge, Mass.-based Vertex Pharmaceuticals said results from a phase II study of VX-765 in patients with treatment-resistant epilepsy showed it met the primary endpoint of safety and tolerability. Results showed a similar safety profile for VX-765 as compared to placebo. Secondary endpoints and additional analyses evaluated the clinical activity of VX-765, and results support the initiation of a larger and longer-duration phase IIb study of VX-765 in people with treatment-resistant epilepsy. Vertex expects to begin this trial as early as the fourth quarter of 2011.

The double-blind, randomized, placebo-controlled phase IIa study of VX-765 enrolled 60 people with treatment-resistant partial onset epilepsy, a type of epilepsy in which seizures start and occur in a specific part of the brain. The study enrolled and dosed people who did not benefit from the use of at least two currently available medicines for partial epilepsy. Patients received six weeks of treatment with VX-765 or placebo following a six-week baseline period to monitor seizure frequency. All patients in the study had at least six partial seizures during the baseline period. Patients were followed for six weeks after the treatment phase to collect additional safety and seizure information. Patients continued to receive standard medicines for epilepsy throughout the study, in addition to VX-765 or placebo. In the study, 48 people received 900 mg of VX-765 three times daily and 12 people received placebo three times daily.

The most common adverse events observed across both treatment arms were headache, dizziness, fatigue and gastrointestinal disorders, and the majority of these adverse events were mild to moderate. The only adverse event 10% or greater in frequency among those treated with VX-765 compared to placebo was dizziness. One person discontinued treatment due to adverse events during the study in the VX-765 treatment group.