Longboard Pharmaceuticals has commenced its Phase 3 DEEp SEA clinical trial to investigate bexicaserin (LP352) as a potential treatment for seizures associated with Dravet syndrome, a rare and severe form of epilepsy. The global study aims to enroll approximately 160 participants aged 2 to 65 years.
The DEEp SEA study is a double-blind, placebo-controlled trial designed to evaluate the efficacy of bexicaserin in reducing the frequency of countable motor seizures, a hallmark of Dravet syndrome. Safety and tolerability are key secondary objectives. Following a 5-week screening period, participants will undergo a 3-week dose titration phase, followed by a 12-week maintenance period on the highest tolerated dose. Eligible participants may then enroll in a 52-week open-label extension study (DEEp OLE).
Regulatory Support and Clinical Development
Bexicaserin, an oral, centrally acting 5-hydroxytryptamine 2C (5-HT2C) receptor superagonist, has received both Orphan Drug and Rare Pediatric Disease designations from the U.S. Food and Drug Administration (FDA) for the treatment of Dravet syndrome. These designations provide Longboard with incentives such as tax credits, exemption from user fees, and potential market exclusivity upon approval. Additionally, the Rare Pediatric Disease designation offers the opportunity to receive a Priority Review Voucher, potentially expediting the review of another Longboard compound.
"We are thrilled to receive both Rare Pediatric Disease and Orphan Drug designations for bexicaserin in Dravet syndrome," said Dr. Randall Kaye, Longboard’s Chief Medical Officer. "We appreciate the FDA’s ongoing support and look forward to initiating our global Phase 3 DEEp program, starting with DEEp SEA in Dravet syndrome in the coming weeks."
Bexicaserin's Mechanism of Action and Prior Clinical Data
Dravet syndrome is a developmental and epileptic encephalopathy (DEE) characterized by frequent, prolonged seizures that are often resistant to conventional treatments. Bexicaserin is designed to selectively bind to the 5-HT2C receptor in the brain and spinal cord, modulating neuronal activity to reduce seizures.
Data from the Phase 1b/2a PACIFIC trial demonstrated that bexicaserin led to significant reductions in seizure frequency in children with Dravet syndrome and other DEEs. In a subset of four Dravet patients, the median seizure frequency was reduced by 72.1%. The treatment was generally well-tolerated, with common side effects including sleepiness, decreased appetite, constipation, and diarrhea.
Addressing Unmet Needs in Dravet Syndrome
"I am pleased to see Longboard’s recent progress in Dravet syndrome — first, with rare pediatric disease and orphan drug designations, and now with the initiation of the DEEp SEA study," said Mary Anne Meskis, Founding Member and Executive Director of the Dravet Syndrome Foundation. "A large unmet need still exists not only in Dravet, but in so many other rare epileptic conditions."
The DEEp SEA study is part of a broader DEEp program that will take place across approximately 80 sites globally and include approximately 480 participants with various DEEs. This comprehensive approach underscores Longboard's commitment to developing transformative medicines for neurological diseases.
