Interim analysis of a 5-year, post-approval study of the NeuroPace Responsive Neurostimulation system support prior findings that the device is safe and effective in reducing medically intractable focal seizures in adults.
Jerzy P. Szaflarski, MD, PhD
One-year interim findings of a 5-year, post-approval study assessing the NeuroPace Responsive Neurostimulation (RNS) system support that the system is safe and effective in treating medically intractable focal seizures. The system was granted regulatory approval in 2013.
Presented by Jerzy P. Szaflarski, MD, PhD, director, division of epilepsy, University of Alabama at Birmingham, at the 73rd annual meeting of the American Epilepsy Society (AES), December 6-10, 2019, in Baltimore, Maryland, the data thus far include 191 adult patients, and show a greater reduction of seizures than the initial pivotal trial of the system at the same time point.
All told, the median seizure frequency reduction with the neurostimulation device was 68% (interquartile range [IQR], 16.1—96) at 1 year compared to 44% in the pivotal trial. Additionally, the responder rate was 61% (95% CI, 52.3­–69.0) at the end of the first year.
“Experience gained in the pivotal and long-term open-label studies with clinical use of brain-responsive neurostimulation could explain these improved outcomes, especially since the demographic and seizure characteristics of post-approval study patients are similar,” Szaflarski and colleagues wrote.
The average patient age was 36.7 years, with a mean epilepsy duration of 16.9 years. At baseline, the median seizure frequency was 5.7 (IQR, 2.7—16.7) seizures per month. The average follow-up was 1.4 years (range, 0–3.8) with a cumulative 265 patient implant years at this interim point. Overall, 128 patients had ≥1-year follow-up and were thus included in the efficacy analyses.
Of those with ≥1 year of follow-up, 34.4% experienced at least 1 period lasting 6 or more months without seizures, and 42.2% reported a 90% or greater reduction in seizures in their most recent 6-month follow-up.
Safety outcomes were similar to those previously observed, with no unanticipated serious adverse events (AEs) related to the device occurring. Of the 191 patients, 4 reported a serious AE related to intracranial hemorrhage, though they were deemed unassociated with seizure-related trauma. A single patient had mild right upper extremity weakness; 1 patient had a transient headache and facial droop; 1 had transient confusion, seizures, and left visual field deficit; and 1 was asymptomatic. There was also cerebrospinal fluid leakage reported by 2 patients at 1 of the 30 sites. The rate of infection was 2.0% per procedure (initial implant, replacement, explant or lead revision), and all were soft tissue only.
“This early experience in a prospective post-approval study continues to support the safety and effectiveness of treatment of medically intractable focal seizures with the RNS System. Safety and efficacy will be further evaluated as the enrollment approaches the planned 300 patients and additional follow-up data are available,” Szaflarski et al. detailed.
Just last year at the 2018 AES annual meeting, NeuroPace announced the results of a 9-year, long-term study of the device’s success in patients with drug-resistant epilepsy, reporting that about 75% of patients achieved at least a 50% reduction in seizures, and approximately 33% of patients achieved at least a 90% reduction in seizures. Additional clinical outcomes included 28% of patients experiencing seizure-free periods of 6 months or longer, and 18% of patients experiencing those same periods of 1-year or longer. The quality of life measures, such as memory and cognition, were sustained through the 9-year study period, with no reported chronic stimulation-related adverse effects.2
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1. Szaflarski JP, Morrell MJ. Interim Safety and Effectiveness Outcomes from a Prospective Post-Approval Trial of the RNS System. Presented at: American Epilepsy Society 2019 Meeting; December 7—10; Baltimore, Maryland. Abstract 1.228.
2. NeuroPace Announces Final Results from the Largest Prospective Clinical Study in the Field of Neuromodulation with 9-Year Follow-Up at the 2018 American Epilepsy Society Annual Meeting [press release]. New Orleans, Lousiana; NeuroPace; Published December 3, 2018. neuropace.com/neuropace-announces-final-results-largest-prospective-clinical-study. Accessed December 8, 2019.