Supernus Announces Promising Interim Data from Ongoing Open-Label Phase 2a Study of SPN-817 in Epilepsy

 SPN-817 is a novel, first-in-class highly selective acetylcholinesterase (AChE) inhibitor for epilepsy

Company to host webcast today at 4:30 p.m. ET to discuss the interim data

ROCKVILLE, Md., May 23, 2024 (GLOBE NEWSWIRE) -- Supernus Pharmaceuticals, Inc. (Nasdaq: SUPN), a biopharmaceutical company focused on developing and commercializing products for the treatment of central nervous system (CNS) diseases, today announced data from the planned interim analysis of the exploratory open-label Phase 2a clinical study of SPN-817 for treatment-resistant seizures. The study is examining the safety and tolerability of SPN-817 as adjunctive therapy in adult patients with treatment-resistant seizures, as well as finding effective doses in various treatment-resistant seizure types. The interim analysis is as of May 1, 2024, and is based on 41 enrolled subjects, of which 19 completed the maintenance period. Of these 19 subjects, 16 subjects had focal seizures.

Summary of the Interim Data

• 75% median focal seizure reduction at the 3mg to 4mg twice daily doses in the maintenance period.
• 86% median focal seizure reduction at the 3mg to 4mg twice daily doses in the open label extension period.
• Responder analysis across all doses in maintenance period:
  • 81% of subjects with focal seizures had 30% or more seizure reduction.
  • 63% of subjects with focal seizures had 50% or more seizure reduction.
  • 19% of subjects with focal seizures had 75% or more seizure reduction.
• Median focal seizure reduction with more severe subjects (greater than 11.3 mean baseline number of seizures per 28-day period):
  • 74% in the maintenance period.
  • 86% in the open label extension period.
• Median seizure reduction in subjects with three or more other anti-seizure medications (ASMs):
  • 70% in the maintenance period.
  • 60% in the open-label extension period.
• Responder analysis in subjects across all doses with three or more ASMs in maintenance period:
  • 100% of subjects with focal seizures had 30% or more seizure reduction.
  • 82% of subjects with focal seizures had 50% or more seizure reduction.
  • 27% of subjects with focal seizures had 75% or more seizure reduction.
• Overall focal seizure reduction (all doses, 1mg to 4mg twice daily):
  • 58% median seizure reduction in the maintenance period.
  • 38% median seizure reduction in the open label extension period.
• Assessment by Epitrack, a validated cognitive screening tool that is designed for patients with epilepsy, indicated that 83% of twelve subjects from whom data are available, was equally split into those who showed improvement and those who had no change in cognitive function.
• SPN-817 was safe and had acceptable tolerability with a discontinuation rate due to adverse events (AEs) of 22% in the titration period and 2.4% in the maintenance period.
• Most common AEs related to the drug were consistent with the known profile of acetylcholinesterase inhibitors and included nausea, diarrhea, headache, dizziness, and decreased appetite. Additional AEs such as fatigue, insomnia, vomiting, blurred vision, somnolence, and irritability were observed.

“This planned interim analysis of our Phase 2a clinical study provides early, yet what seems to be strong evidence, of the clinical utility of SPN-817 in epilepsy. In addition, the data provide important insights for the design of the upcoming Phase 2b clinical study that we plan on initiating before year end 2024,” said Jack Khattar, President and CEO of Supernus. “We will continue to analyze the valuable information provided on safety and tolerability of SPN-817 and the effective dose range in subjects. We will extend the current Phase 2a study to explore potential approaches that we have identified to further improve the tolerability during titration. Full topline results from the Phase 2a study excluding this new extension period are still on track to report in the second half of 2024. We believe SPN-817 could provide a novel, differentiated treatment option for this hard-to-treat and underserved patient population by currently available therapies.”