Medtronic prepares to head back to FDA with deep brain stimulation for epilepsy

The Activa neurostimulator for Parkinson's disease--Courtesy of Medtronic

Medtronic ($MDT) has published detailed results for the first time of a 5-year trial for deep brain stimulation therapy in treatment-resistant epilepsy. The device giant has said that it will make another run at an FDA approval for its DBS device in that indication.

This is the largest clinical study of DBS to treat adults with refractory epilepsy characterized by partial-onset seizures. Dubbed SANTE (stimulation of the anterior nucleus of the thalamus in epilepsy), the study is a pivotal trial designed to support U.S. approval. But after narrowly passing an FDA panel review in 2010, the agency requested additional data to support an approval. Initial 5-year SANTE data were published in December 2012. The latest data are appearing in the March issue of the journal Neurology.

The FDA has approved Medtronic DBS Therapy to treat refractory Parkinson's disease, essential tremor, dystonia and obsessive-compulsive disorder. The latter two approvals are via a Humanitarian Use Device pathway, which is intended for use by fewer than 4,000 people annually in the U.S. and does not require the same strict clinical proof of efficacy.

The 5-year SANTE data actually show an increase in efficacy over time. The median seizure reduction rate was 69% from baseline at 5 years, up from 41% at one year. The responder rate, based on a more than reduction in seizure frequency by more than half, was 68% at 5 years, up from 43%. And 16% of patients reported being seizure-free for at least 6 months.

Overall, the study found that DBS stimulation results in reduced seizure frequency of 69%. But the trial had a 34% rate of serious, device-related adverse events at 5 years. The most common was implant site infection, which occurred at a rate of 10%. Device-related implantation problems were reversible and there were no device-related deaths, Medtronic said.

There are 2.3 million adults with epilepsy in the U.S., of which at least 30% are considered refractory after a failure to control seizures using at least two antiepileptic drugs, according to the company.

"The latest SANTE study findings provide important insights into the long-term benefits of DBS therapy, which are encouraging for patients with severe partial epilepsy who are resistant to other treatments and are not candidates for resective epilepsy surgery," Dr. Vicenta Salanova, a professor of neurology at Indiana University School of Medicine and lead author of the publication, said in a statement.

She continued, "Long-term treatment efficacy is critical for people suffering from epilepsy, and it is particularly remarkable that DBS therapy is helping treatment-resistant patients to achieve sustained reduction in seizure frequency and severity over time while also leading to meaningful improvements in quality of life."

- here are the release and the Neurology results

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