Phase III clinical study: Vimpat demonstrates fewer partial-onset seizures versus placebo in adults with epilepsy

UCB today announced that the antiepileptic drug (AED) Vimpat® (lacosamide) (C-V) demonstrated significantly fewer partial-onset seizures versus placebo in adults living with epilepsy, according to a Phase III clinical study published online in Epilepsia.

This study was one of three that supported the approval of Vimpat by the U.S. Food and Drug Administration (FDA) in 2008 for use as an add-on therapy for the treatment of partial-onset seizures in people with epilepsy who are 17 years and older.  Previous studies have demonstrated that Vimpat has a novel mechanism of action.  It is available as oral tablets and as an intravenous (IV) infusion to allow for consistent treatment in a hospital setting.  Although Vimpat demonstrated clinical benefits at both doses in this study (400 and 600 mg/day), as measured by several efficacy endpoints, the maximum FDA-approved dose is 400 mg/day.

"This and other studies demonstrate Vimpat's established efficacy and tolerability, with almost 3,000 patient years of exposure.  In addition, no clinically significant pharmacokinetic drug interactions were observed in clinical trials when Vimpat was used in combination with seven different AEDs as well as several commonly used medications," said James Zackheim, PhD, CNS Medical Director at UCB.

Uncontrolled seizures and medication side effects pose challenges to independent living, learning and employment, and the goal of epilepsy therapy is seizure freedom with minimal side effects. While treatment with one drug is ideal, fewer than half (47%) of newly-diagnosed patients become seizure-free with their first AED.

"My clinical and study experience with Vimpat reinforces its role in a new approach to epilepsy treatment.  If a monotherapy is not effective, adding another AED may help some patients attain treatment success sooner, compared to a monotherapy-to-monotherapy approach," said study author and lead Vimpat clinical trial investigator Steven Chung, MD, Director of Clinical Epilepsy Research at Barrow Neurological Institute at St. Joseph's Medical Center in Phoenix.

Vimpat Demonstrated Significant Efficacy and Greater Rates of Seizure Freedom Versus Placebo

In this double-blind, placebo-controlled Phase III study, patients taking 400 and 600 mg/day of Vimpat had significantly greater reductions in seizure frequency per 28 days from baseline versus placebo (37.3% for Vimpat 400 mg/day>

In addition, the 50 percent responder rate was 38.3% for those taking Vimpat 400 mg/day [P<0.001] and 41.2% for those taking Vimpat 600 mg/day [P<0.001], versus only 18.3% of patients taking placebo.  The 50 percent responder rate is defined as the proportion of patients who experience a 50 percent or greater reduction in seizure frequency from baseline to maintenance period.

In a secondary analysis, more patients taking Vimpat achieved seizure freedom throughout the maintenance period compared to placebo.  Among patients taking Vimpat 400 mg/day and 600 mg/day, 2.5% (4 patients out of 160) and 8.1% (5 patients out of 62), respectively, were seizure-free throughout the maintenance phase, compared to none of the placebo group patients.  

In the study, the most common dose-related adverse events included dizziness (44.9%), nausea (13.3%), diplopia (13%), blurred vision (12.6%), headache (12.3%), vomiting (12.3%), and tremor (11%).  Most adverse events were mild to moderate in intensity.  These data are consistent with results from other clinical trials of Vimpat.