Pivotal Bexicaserin Trial Completes Randomization in Rare Childhood Epilepsies

Lundbeck has completed randomization in the Phase III DEEp OCEAN trial (NCT06719141), marking a key milestone in the clinical development of bexicaserin, an investigational oral therapy for seizures associated with developmental and epileptic encephalopathies (DEEs). The global placebo-controlled study enrolled more than 350 children and adults aged 2 to 65 years, making it the broadest pivotal trial to date in this diverse group of severe childhood-onset epilepsies.

The completion of enrollment allows all participants to progress through the double-blind treatment phase before eligible patients enter a 52-week open-label extension study. Lundbeck expects headline efficacy and safety results by the end of 2026 or during the first quarter of 2027.

Broad Phase III Study Targets Diverse DEE Population

Developmental and epileptic encephalopathies are a heterogeneous group of rare neurological disorders characterized by treatment-resistant seizures, developmental delay, and cognitive impairment. Although conditions such as Dravet syndrome and Lennox-Gastaut syndrome (LGS) have approved treatment options, many other genetic and clinical DEE subtypes remain without targeted antiseizure therapies.

Unlike previous pivotal epilepsy studies that focused on individual syndromes, DEEp OCEAN enrolled patients across a wide range of DEEs, including more than 60 genetically defined syndromes. Investigators expect this broad population to provide clinically meaningful evidence on the potential utility of bexicaserin across multiple rare epilepsy subtypes encountered in routine practice.

Bexicaserin Uses Selective 5-HT2C Receptor Activation

Bexicaserin is an investigational oral 5-HT2C receptor superagonist that selectively activates a serotonin receptor involved in regulating neuronal excitability.

The therapy works through a dual mechanism by enhancing inhibitory neuronal signaling while suppressing excessive excitatory activity, an approach intended to reduce seizure frequency across different DEE etiologies. Earlier Phase IIa PACIFIC data showed reductions in multiple seizure types in patients with diverse developmental and epileptic encephalopathies, supporting advancement into Phase III testing.

The U.S. Food and Drug Administration and Chinese regulators have both granted Breakthrough Therapy Designation to bexicaserin for treating seizures associated with DEEs. The drug remains investigational and has not received marketing approval in any country.

Phase III Trial Evaluates Seizure Reduction and Safety

DEEp OCEAN is a randomized, double-blind, placebo-controlled multicenter trial evaluating the efficacy, safety, and tolerability of bexicaserin in reducing countable motor seizure frequency.

Following a screening period of up to 35 days, participants receive either bexicaserin or placebo three times daily during a 15-week treatment phase comprising a three-week dose titration followed by 12 weeks of maintenance therapy. Pediatric participants receive weight-based dosing. After treatment, eligible participants may continue into a 52-week open-label extension study to assess longer-term safety and treatment effects.

Parallel Dravet Syndrome Study Continues Enrollment

Professor Ingrid Scheffer, lead investigator of the DEEp OCEAN trial, said the study includes the most diverse DEE population evaluated in a pivotal epilepsy program, reflecting the broad genetic and clinical heterogeneity seen in real-world patients.

Johan Luthman, Executive Vice President and Head of Research and Development at Lundbeck, said completion of randomization represents an important milestone achieved through the collaboration of patients, families, investigators, and advocacy groups. He added that recruitment continues to progress well in the companion DEEp SEA Phase III trial (NCT06660394), which specifically evaluates bexicaserin in Dravet syndrome, with completion of randomization expected within the next few months.

Next Milestone Expected in Late 2026

With enrollment complete, Lundbeck will now focus on completing patient follow-up and data collection for DEEp OCEAN. If the trial demonstrates clinically meaningful seizure reduction with an acceptable safety profile, bexicaserin could become one of the first therapies supported by pivotal evidence across a broad range of developmental and epileptic encephalopathies rather than a single epilepsy syndrome. The anticipated Phase III readout in late 2026 or early 2027 will determine the next steps toward potential regulatory submissions.

 Reference

Lundbeck announces last patient randomized in DEEp OCEAN, a large Phase III trial in developmental and epileptic encephalopathies (DEEs) – H. Lundbeck A/S