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Epilepsy

Long-Term Safety and Effectiveness of Fenfluramine in Pediatric and Adult Patients with Lennox-Gastaut Syndrome

Strategic Insights

— 2 min read

Research published in Epilepsy & Behavior reveals the long-term safety and effectiveness of fenfluramine in patients with Lennox-Gastaut syndrome (LGS), a severe form of epilepsy characterized by multiple seizure types. The study, led by researchers from the University of Colorado Anschutz Medical Campus, analyzed data from an open-label extension study of 247 patients aged 2-35 years who participated in the randomized controlled trial (RCT) and continued in the OLE study (NCT03355209). The findings demonstrate sustained reductions in seizures and improvement in global functioning observed over a mean fenfluramine daily dose of 0.4 ± 0.1 mg/kg/day and median fenfluramine exposure of 364 days.

Key Takeaways:

  • The study aimed to describe the long-term safety and effectiveness of fenfluramine in pediatric and adult patients with LGS from the final analysis of an open-label extension study.
  • A total of 247 patients enrolled in the study, with 158 (64.0 %) patients completing the OLE.
  • Mean ± SD age of the patients was 14.3 ± 7.6 years, and median fenfluramine exposure was 364 days (range, 19-537).
  • The most common treatment-emergent adverse events (TEAEs) reported in 10 % of patients were decreased appetite, fatigue, nasopharyngitis, seizure, and pyrexia.
  • No cases of valvular heart disease or pulmonary arterial hypertension were reported.
  • A significant reduction in seizures associated with a fall was observed, with a median change of -31.1 % (n = 240; P < 0.001) from Month 2 to the end of the study.
  • The Researchers concluded that these results support the long-term safety and effectiveness of fenfluramine in patients with LGS, with no new safety signals identified and sustained reductions in seizures and improvement in global functioning observed.

Statistics:

  • 247 patients enrolled in the study, with 158 (64.0 %) patients completing the OLE.
  • Mean ± SD age of the patients was 14.3 ± 7.6 years.
  • Median fenfluramine exposure was 364 days (range, 19-537).
  • Mean ± SD fenfluramine daily dose was 0.4 ± 0.1 mg/kg/day.
  • 10 % of patients reported treatment-emergent adverse events (TEAEs).
  • No cases of valvular heart disease or pulmonary arterial hypertension were reported.
  • A significant reduction in seizures associated with a fall was observed, with a median change of -31.1 % (n = 240; P < 0.001) from Month 2 to the end of the study.

Sources:

  • Final analysis from an open-label extension study of fenfluramine for the treatment of seizures in Lennox-Gastaut syndrome: long-term impact on patients and caregivers. Epilepsy & Behavior, 2025;173:110753.
  • Academic Press Inc Elsevier Science, 525 B St, Ste 1900, San Diego, CA 92101-4495, USA. (Elsevier - www.elsevier.com; Epilepsy & Behavior - www.journals.elsevier.com/epilepsy-and-behavior/)
  • Researchers from University of Colorado Anschutz Medical Campus. (2025). Researchers from University of Colorado Anschutz Medical Campus Provide Details of New Studies and Findings in the Area of Epilepsy (Final analysis from an open-label extension study of fenfluramine for the treatment of seizures in ...). Pediatrics Week. November 1, 2025; p 643.

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