The US Food and Drug Administration (FDA) has granted premarket approval for Medtronic’s deep brain stimulation (DBS) therapy as adjunctive treatment for reducing the frequency of partial-onset seizures, in individuals 18 years of age or older who are refractory, or drug-resistant, to three or more antiepileptic medications. DBS therapy for epilepsy delivers controlled electrical pulses to a target in the brain called the anterior nucleus of the thalamus (ANT), which is part of a network involved in seizures.
According to the Epilepsy Foundation, 3.4 million individuals in the United States have epilepsy. Antiepileptic drug (AED) medication is the primary treatment to control seizures; however, up to one third of individuals with epilepsy have seizures that do not successfully respond to AEDs.
“Many patients in the United States with severe epilepsy are not able to control their seizures with currently-available drugs and are not candidates for potentially curative surgery,” said Robert Fisher, director of the Stanford Epilepsy Center, Stanford University, USA, and lead principal investigator of the SANTE trial. “Epilepsy that is refractory to AED treatment is an unsolved problem, and DBS therapy will now serve as an important new treatment option, including for people with poorly localised or multiple regions of seizure origin.”
The FDA approval is based on both the blinded phase and the 7-year follow-up data collected in Medtronic’s clinical trial called SANTE (Stimulation of the Anterior Nucleus of the Thalamus in Epilepsy). The SANTE trial was a prospective, randomised, double-blind pivotal study to evaluate the use of DBS therapy for patients with medically refractory epilepsy with partial-onset seizures, with or without secondary generalization, that were drug-resistant to three or more antiepileptic medications. The trial collected data from 110 patients who were implanted with a Medtronic DBS system at 17 centres located in the U.S.
- The median total seizure frequency reduction from baseline was 40.4 percent versus 14.5% for the placebo group at three months, and 75% at 7-years, with open-label ongoing therapy.
- Twenty subjects (18%) experienced at least one 6-month seizure-free period between implant and year seven, including eight subjects (7%) who were seizure-free for the preceding two years.
- Seizure severity and quality of life scales both showed statistically significant improvements from baseline at year seven.
- No significant cognitive declines or worsening of depression scores were observed through the blinded phase or at year seven. Improved scores were observed at 7-years on measures of executive functions and attention.