Epilepsia Open publishes results of post hoc data analysis of FINTEPLA® (fenfluramine) in patients with Lennox-Gastaut syndrome

The analysis included data from patients treated with FINTEPLA who completed an open-label extension (OLE) after receiving either FINTEPLA or placebo during the initial Phase 3, 14-week randomized controlled trial (RCT). Study participants who transitioned from placebo to FINTEPLA in the OLE experienced reduction in seizure frequency and global functioning improvement as early as one month after treatment initiation, with further reductions observed in subsequent months as the mean dose increased. This outcome was consistent with patients treated with FINTEPLA from the start.

"LGS remains one of the most challenging rare epilepsies to manage, and families and clinicians often have limited visibility into what response may look like in the first months of treatment," said Hugo Xi, MD, MBA, Head of Medical for Epilepsy and Rare Syndromes at UCB. "These findings provide important insight into the treatment trajectory of FINTEPLA, helping inform conversations around early response, dose titration, and the potential value of continued treatment over time."

Highlights from the post hoc analysis²

Of 263 patients enrolled in the RCT, 247 (93.9%) continued into the OLE. Of those, 151 (61.1%) completed 12 months of FINTEPLA treatment in the OLE and were included in the post hoc analysis. The analysis evaluated changes over time in the number of seizures associated with a fall, clinically meaningful improvement (defined as "much improved" or "very much improved") on the Clinical Global Impression–Improvement (CGI-I) scale as assessed by parent/caregiver and investigator, and adverse events in two groups: patients randomized to placebo in the RCT who switched to FINTEPLA in the OLE (PBO-FFA; n=59), and those who received FINTEPLA in both the RCT and OLE (FFA-FFA; n=92).

• Rapid onset of effect: At Month 1 of the OLE, patients in the PBO-FFA group experienced a -32.1% median reduction in seizures associated with a fall compared with baseline. Patients in the FFA-FFA group experienced a -48.5% median reduction.
• Continued improvement over time: Seizure reductions improved to -48.2% over Months 4-6 in patients in the PBO-FFA group, which was similar to the reductions seen at 4-6 months in the FFA-FFA group (-44.2%).
• Global functioning improvements: Clinically meaningful improvements in patient global functioning (CGI-I) were observed shortly after patients in the PBO-FFA group initiated FINTEPLA. By Month 12, 52.6% and 46.3% of patients in the PBO-FFA group were rated as demonstrating clinically meaningful improvement by parent/caregiver and investigator, respectively. Similar improvements were observed in the FFA-FFA group, with 50.0% and 50.5% of patients receiving those ratings, respectively.
• Predictable and well tolerated safety profile: The incidence of most commonly reported treatment-emergent adverse events (TEAEs), including decreased appetite, somnolence, fatigue, diarrhea, pyrexia, and nasopharyngitis, increased in the PBO-FFA group at the time of treatment initiation, as expected. However, the incidence of most commonly reported TEAEs (decreased appetite, somnolence, fatigue, and diarrhea) decreased over time with continued FINTEPLA treatment, suggesting an acceptable long-term tolerability.

Note: As these results were obtained in a post hoc analysis, no conclusions of efficacy should be made.

For further information, contact UCB:

US Communications

Becky Malone

T +1.919.605.9600

becky.malone@ucb.com

Corporate Communications, Media Relations

Laurent Schots

T +32.2.559.92.64

laurent.schots@ucb.com

Investor Relations

Antje Witte

T +32.2.559.94.14

antje.witte@ucb.com

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.³ It typically starts during childhood and persists into adulthood.^3,4 Approximately 50% of infants with a severe DEE evolve over time to be diagnosed with LGS.^3,5 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.⁴ Seizures largely remain drug-resistant into adulthood on currently available medications.^4,6 Sudden unexpected death in epilepsy (SUDEP) is a major concern for patients and families with LGS.⁷

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 more than 9000 people in approximately 40 countries, the company generated revenue of € 7.7 billion in 2025. UCB is listed on Euronext Brussels (symbol: UCB). Follow us on Twitter: @UCBUSA.

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Indication and Important Safety Information about FINTEPLA^® (fenfluramine) in the US

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.

FINTEPLA^® is a registered trademark of the UCB Group of Companies.

References:

1. FINTEPLA (fenfluramine) oral solution: U.S. prescribing information. Smyrna, GA: UCB, Inc. October 2025.
2. Nabbout R, Devinsky O, Lagae L, et al. Changes in effectiveness and safety in patients with Lennox-Gastaut syndrome transitioning from the fenfluramine randomized controlled trial to open-label extension study. 
3. 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):1398-1442.
4. NORD. LGS. Available at: https://rarediseases.org/rare-diseases/lennox-gastaut-syndrome. Last accessed: June 2026.
5. Berg AT, Levy SR, Testa FM. Evolution and course of early life developmental encephalopathic epilepsies: Focus on Lennox-Gastaut syndrome. Epilepsia. 2018 ;59(11):2096-2105.
6. LGS Foundation. What is Lennox-Gastaut Syndrome? Available at: https://www.lgsfoundation.org/about-lgs-2/what-is-lennox-gastaut-syndrome/. Last accessed: April 2026.
7. LGS Foundation. Sudden Unexpected Death in Epilepsy (SUDEP). Available at: https://www.lgsfoundation.org/sudep/. Last accessed: April 2026.

FINTEPLA^® is a registered trademark of the UCB Group of Companies.

©2026 UCB, Inc., Smyrna, GA 30080. All rights reserved. US-FA-2600260

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