Lundbeck Completes Randomization in DEEp SEA Trial for Bexicaserin in Dravet Syndrome

H. Lundbeck A/S has announced that the last patient has been randomized in DEEp SEA, a global Phase III clinical trial evaluating the efficacy, safety, and tolerability of the investigational molecule bexicaserin in individuals with Dravet syndrome. This milestone marks another significant step in the broader Phase III DEEp program, with randomization now complete in both pivotal trials.

Dravet syndrome is a rare and severe form of childhood-onset epilepsy, classified as a developmental and epileptic encephalopathy (DEE). It is characterized by treatment-resistant seizures, which can significantly impact the quality of life for those affected. The DEEp SEA trial, which enrolled over 100 participants aged two to 65 years, is one of two pivotal trials in the global Phase III DEEp program. The second trial, DEEp OCEAN, completed randomization in July 2026 and is evaluating bexicaserin in children and adults with DEEs, including Lennox-Gastaut syndrome, but excluding Dravet syndrome.

Bexicaserin is an investigational, oral, highly selective superagonist of the 5-HT2C receptor subtype. It acts via a dual mode of action, increasing inhibitory and decreasing excitatory neuron function, consistent with the reduction in seizures associated with DEEs arising from various etiologies. The DEEp SEA trial, which is being conducted under the clinical trial identifier NCT06660394, is designed as a randomized, double-blind, placebo-controlled multicenter trial. Participants are randomized to receive either bexicaserin or placebo three times daily, with weight-based dosing used for pediatric participants. The trial aims to evaluate the efficacy, safety, and tolerability of bexicaserin in reducing countable motor seizure frequency in patients with Dravet syndrome.

The DEEp SEA trial comprises a screening period of up to 35 days, followed by a 15-week treatment period consisting of a 3-week titration phase and a 12-week maintenance phase. Following treatment, participants complete a taper period and safety follow-up or may transition into the 52-week DEEp open-label extension (OLE) study. The FDA has granted Breakthrough Therapy designation to bexicaserin for the treatment of seizures associated with DEEs for patients two years of age and older. Bexicaserin has also recently been granted Breakthrough Therapy designation in China for the treatment of seizures associated with DEEs.

Tarek Samad, Executive Vice President and Head of Research & Development at Lundbeck, stated, "Completing randomization in DEEp SEA is an important milestone in our work to evaluate bexicaserin in people living with Dravet syndrome. This marks another step forward for the broader Phase III DEEp program and supports our ongoing efforts to advance research for people living with these severe epilepsies." Samad highlighted the extraordinary commitment of patients and their families, investigators, study teams, and advocacy communities around the world, expressing deep gratitude for their continued contribution as the study progresses.

The DEEp SEA trial is part of a larger Phase III clinical program (the DEEp program) evaluating bexicaserin for the treatment of seizures in participants with any type of DEE. The program includes the DEEp OCEAN trial, which is evaluating bexicaserin in children and adults with DEEs, including Lennox-Gastaut syndrome, but excluding Dravet syndrome. Both trials are designed to assess the efficacy, safety, and tolerability of bexicaserin in reducing countable motor seizure frequency in patients with Dravet syndrome and other DEEs.

H. Lundbeck A/S, a biopharmaceutical company focusing exclusively on brain health, is committed to improving the lives of people with neurological and psychiatric diseases. With more than 70 years of experience in neuroscience, the company is dedicated to advancing brain health by curiously exploring new opportunities for treatments. The company's products are available in more than 80 countries, and its research and development programs aim to tackle some of the most complex neurological challenges.