ATLANTA, Georgia — UCB, a global biopharmaceutical company, today announced that the final analysis of an open-label extension (OLE) study with the objective to describe long-term safety and effectiveness of FINTEPLA (fenfluramine) in Lennox-Gastaut syndrome (LGS) was published in Epilepsy & Behavior.2 No new or unexpected treatment-emergent adverse events (TEAEs) were reported.2 Children and adults aged 2-35 years treated with fenfluramine showed a significant sustained reduction in frequency of seizures associated with a fall (drop seizures) from Month 2 of OLE to end of study compared with baseline and an improvement in global functioning reported by caregivers and investigators. Parents/caregivers reported improvements in social interactions and activities, feelings of stigma, general health, quality of life, and their own anxiety.2 These results follow final analysis of OLE study evaluating safety and effectiveness of fenfluramine in Dravet syndrome earlier this year, showing long-term tolerability and sustained reduction in monthly convulsive seizure frequency.3
Kelly G Knupp, Associate Professor of Pediatrics and Neurology at the CU Anschutz School of Medicine and coauthor of the paper, said, “These data reinforce the long-term safety and tolerability of fenfluramine in children and adults living with Lennox-Gastaut syndrome, a condition with a significant unmet medical need. The sustained reduction in seizure frequency, coupled with the reported improvements in quality of life for both patients and their families, underscores the importance of addressing not just the clinical but also the emotional and social challenges faced by these families every day.”
Highlights from the OLE
247 patients (mean age 14.3±7.6 years) were enrolled from study sites in North America, Europe, and Australia, with a median fenfluramine exposure of 364 days (range: 19–537) and a mean daily dose of 0.4±0.1 mg/kg/day (n=246). Meaningful improvements were seen across the key study endpoints listed below:2
- Common treatment-emergent adverse events (TEAEs) reported in ≥10% of patients included decreased appetite, fatigue, nasopharyngitis, seizures, and pyrexia, with no cases of valvular heart disease or pulmonary arterial hypertension observed. 5.3% of patients discontinued the study due to TEAEs.
- A significant median percentage change in the frequency of seizures associated with a fall from Month 2 to the end of the study (−31.1%, P<0.0001, n=240, modified intent-to-treat (mITT) population), with reductions of −27.6% in pediatric patients (n=170, P=0.0005) and −40.0% in adults (n=70, P<0.0001).
- At the last visit, parents/caregivers and investigators reported an improvement in 59.9% (n=142/237) and 57.0% (n=135) of patients, respectively, on the Clinical Global Impression–Improvement (CGI-I) scale.
- The Quality of Life in Childhood Epilepsy Questionnaire (QOLCE) was completed by parents/caregivers at pre-RCT baseline and at Month 12 of the OLE. From baseline through Month 12 of the OLE period, the mean change in the overall QoL score, calculated as the average of 16 subscale scores, was 2.9 points (n=148, P=0.0166), indicating improvement.
- A limitation of this study was its open-label design. Additionally, bias could be suggested in the effectiveness data due to 23.1% of patients withdrawing for lack of efficacy. The COVID-19 pandemic impacted study duration, causing delays in data capture.
About Lennox-Gastaut syndrome (LGS)
Lennox-Gastaut syndrome (LGS) is a rare, severe developmental and epileptic encephalopathy (DEE) characterized by the presence of tonic seizures and at least one additional seizure type and severe developmental delays.4 It typically starts during childhood and persists into adulthood.4,5 Approximately 50% of infants with a severe DEE evolve over time to be diagnosed with LGS.5 LGS has far-reaching effects beyond seizures; impairments with developmental delay culminating in challenges with cognition, communication, psychiatric symptoms, sleep, behavior, and mobility are common.5 Seizures largely remain drug-resistant into adulthood on currently available medications.5,6 Sudden unexpected death in epilepsy (SUDEP) is a major concern for patients and families with LGS.7
About FINTEPLA
Important Safety Information about FINTEPLA® (fenfluramine) in the US
INDICATIONS AND USAGE
FINTEPLA is indicated for the treatment of seizures associated with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS) in patients 2 years of age and older.
IMPORTANT SAFETY INFORMATION
BOXED WARNING: VALVULAR HEART DISEASE and PULMONARY ARTERIAL HYPERTENSION
- FINTEPLA can cause valvular heart disease and pulmonary arterial hypertension.
- Echocardiogram assessments are required before, during, and after treatment with FINTEPLA.
- FINTEPLA is available only through a restricted program called the FINTEPLA REMS.
CONTRAINDICATIONS
FINTEPLA is contraindicated in patients with hypersensitivity to fenfluramine or any of the excipients in FINTEPLA and with concomitant use, or within 14 days of the administration, of monoamine oxidase inhibitors because of an increased risk of serotonin syndrome.
WARNINGS AND PRECAUTIONS
Valvular Heart Disease and Pulmonary Arterial Hypertension (see Boxed Warning): FINTEPLA can cause valvular heart disease (VHD) and pulmonary arterial hypertension (PAH). Although no patients receiving FINTEPLA developed VHD or PAH in clinical trials for DS and LGS of up to 3 years in duration, cases of VHD and PAH have been reported during use of FINTEPLA in the postmarketing setting. Because of this risk, cardiac monitoring is required prior to starting treatment, during treatment, and after treatment with FINTEPLA concludes. Cardiac monitoring via echocardiogram can identify evidence of VHD and PAH prior to a patient becoming symptomatic, aiding in early detection of these conditions.
Monitoring: Prior to starting treatment, patients must undergo an echocardiogram to evaluate for VHD and PAH. Echocardiograms should be repeated every 6 months, and once 3-6 months post treatment with FINTEPLA.
The prescriber must consider the benefits versus the risks of initiating or continuing treatment with FINTEPLA if any of the following signs are observed via echocardiogram: valvular abnormality or new abnormality; VHD indicated by mild or greater aortic regurgitation or moderate or greater mitral regurgitation, with additional characteristics of VHD (e.g., valve thickening or restrictive valve motion); PAH indicated by elevated right heart/pulmonary artery pressure (PASP >35 mm Hg).
FINTEPLA REMS (see Boxed Warning): FINTEPLA is available only through a restricted distribution program called the FINTEPLA Risk Evaluation and Mitigation Strategy (REMS). Prescribers must be certified by enrolling in the FINTEPLA REMS. Prescribers must counsel patients receiving FINTEPLA about the risk of VHD and PAH, how to recognize signs and symptoms of VHD and PAH, the need for baseline (pretreatment) and periodic cardiac monitoring via echocardiogram during FINTEPLA treatment, and cardiac monitoring after FINTEPLA treatment.
Decreased Appetite and Decreased Weight: FINTEPLA can cause decreases in appetite and weight. Decreases in weight appear to be dose related. Weight should be monitored regularly during treatment with FINTEPLA, and dose modifications should be considered if a decrease in weight is observed.
Somnolence, Sedation, and Lethargy: FINTEPLA can cause somnolence, sedation, and lethargy. Other central nervous system depressants, including alcohol, could potentiate these effects of FINTEPLA. Prescribers should monitor patients for somnolence and sedation and should advise patients not to drive or operate machinery until they have gained sufficient experience on FINTEPLA to gauge whether it adversely affects their ability to drive or operate machinery.
Suicidal Behavior and Ideation: Antiepileptic drugs (AEDs), including FINTEPLA, increase the risk of suicidal thoughts or behaviors in patients taking these drugs for any indication. Patients treated with an AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behaviors, or any unusual changes in mood or behavior.
Withdrawal of Antiepileptic Drugs: As with most AEDs, FINTEPLA should generally be withdrawn gradually because of the risk of increased seizure frequency and status epilepticus. If withdrawal is needed because of a serious adverse reaction, rapid discontinuation can be considered.
Serotonin Syndrome: Serotonin syndrome, a potentially life-threatening condition, may occur with FINTEPLA, particularly during concomitant administration of FINTEPLA with other serotonergic drugs, including, but not limited to, selective serotonin-norepinephrine reuptake inhibitors (SNRIs), selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), bupropion, triptans, dietary supplements (e.g., St. John’s Wort, tryptophan), drugs that impair metabolism of serotonin (including monoamine oxidase inhibitors [MAOIs], which are contraindicated with FINTEPLA), dextromethorphan, lithium, tramadol, and antipsychotics with serotonergic agonist activity. Patients should be monitored for the emergence of signs and symptoms of serotonin syndrome, which include mental status changes, autonomic instability, neuromuscular signs, and/or gastrointestinal symptoms. If serotonin syndrome is suspected, treatment with FINTEPLA should be stopped immediately and symptomatic treatment should be started.
Increase in Blood Pressure: FINTEPLA can cause an increase in blood pressure. Rare cases of significant elevation in blood pressure, including hypertensive crisis, have been reported in adult patients treated with fenfluramine, including patients without a history of hypertension. In clinical trials for DS and LGS of up to 3 years in duration, no pediatric or adult patient receiving FINTEPLA developed hypertensive crisis. Monitor blood pressure in patients treated with FINTEPLA.
Glaucoma: Fenfluramine can cause mydriasis and can precipitate angle closure glaucoma. Consider discontinuing treatment with FINTEPLA in patients with acute decreases in visual acuity or ocular pain.
ADVERSE REACTIONS
The most common adverse reactions observed in DS studies (incidence at least 10% and greater than placebo) were decreased appetite; somnolence, sedation, lethargy; diarrhea; constipation; abnormal echocardiogram; fatigue, malaise, asthenia; ataxia, balance disorder, gait disturbance; blood pressure increased; drooling, salivary hypersecretion; pyrexia; upper respiratory tract infection; vomiting; decreased weight; fall; status epilepticus.
The most common adverse reactions observed in the LGS study (incidence at least 10% and greater than placebo) were diarrhea; decreased appetite; fatigue; somnolence; vomiting.
To report SUSPECTED ADVERSE REACTIONS, contact UCB, Inc. at 1-844-599-2273 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Please see full Prescribing Information , including Boxed Warning and Medication Guide , for additional Important Safety Information on FINTEPLA.
About UCB
UCB, Brussels, Belgium (www.ucb.com) is a global biopharmaceutical company focused on the discovery and development of innovative medicines and solutions to transform the lives of people living with severe diseases of the immune system or of the central nervous system. With approximately 9,000 people in approximately 40 countries, the company generated revenue of €5.3 billion in 2023. UCB is listed on Euronext Brussels (symbol: UCB). Follow us on X (Twitter): @UCBUSA.
About Epilepsy
Epilepsy is a common neurological condition worldwide and affects approximately 50 million people. Epilepsy can develop in any person at any age and is usually diagnosed after a person has had at least two seizures (or after one seizure with a high risk for more) that were not caused by some known medical condition.
About UCB in Epilepsy
For three decades we’ve been committed to people living with epilepsy and their families, surrounding the patient and caregiver through every step of their care journey. At our core we have a responsibility to elevate the healthcare ecosystem. Because of this, we have established our legitimacy on the front lines of epilepsy research, development, and treatment innovation. But our past breakthroughs are only a prologue to our future. We will continue to reimagine how we care for patients, leveraging today’s expertise for a better tomorrow. With so much experience behind us and so much potential ahead, we are more invested than ever in profoundly improving the lives of those living with or caring for those with epilepsy or a rare epilepsy syndrome – through our relentless pursuit of a seizure-free life.
For further information, contact UCB:
Investor Relations
Antje Witte
T: +32.2.559.94.14
email [email protected]
US Communications
Becky Malone
T +1.919.605.9600
Email [email protected]
References
- FINTEPLA (fenfluramine) oral solution: U.S. prescribing information. Smyrna, GA: UCB, Inc. Last accessed: September 2025.
- EPILEPSIA REF TBC
- Scheffer IE, Nabbout R, Lagae L, et al. Long-term safety and effectiveness of fenfluramine in children and adults with Dravet syndrome. Epilepsia. 2025;66(6):1919-32.
- Specchio N, Wirrell EC, Scheffer IE, et al. International League Against Epilepsy classification and definition of epilepsy syndromes with onset in childhood: Position paper by the ILAE Task Force on Nosology and Definitions. Epilepsia. 2022;63(6):1398-442.
- NORD. LGS. Available at: https://rarediseases.org/rare-diseases/lennox-gastaut-syndrome. Last accessed: September 2025.
- LGS Foundation. What is Lennox-Gastaut Syndrome? Available at: https://www.lgsfoundation.org/about-lgs-2/what-is-lennox-gastaut-syndrome/. Last accessed: September 2025.
- LGS Foundation. Sudden Unexpected Death in Epilepsy (SUDEP). Available at: https://www.lgsfoundation.org/sudep/. Last accessed: September 2025.
FINTEPLA® is a registered trademark of the UCB Group of Companies.