NBI-921352 (XEN901)

Neurocrine Biosciences acquired the exclusive rights to NBI-921352 from Xenon Pharmaceuticals. NBI-921352 is a potent, highly selective Nav1.6 sodium channel inhibitor being developed to treat pediatric patients with SCN8A developmental and epileptic encephalopathy (SCN8A-DEE) and other potential indications, including adult focal epilepsy. Neurocrine Biosciences has received a Rare Pediatric Disease Designation from the FDA for NBI-921352.


SCN8A-DEE is a rare disorder that causes a range of symptoms including severe epilepsy, developmental delay, and other medical challenges including a high degree of refractoriness to currently available antiseizure medication. SCN8A-DEE is linked to gain of function mutations in the SCN8A gene, a gene that affects how brain cells function. Mutations on this gene can cause neurological problems including epilepsy, intellectual disabilities, movement disorders, and impaired development. There are currently no approved therapies for this form of pediatric epilepsy.

Neurocrine Biosciences has received orphan drug and rare pediatric disease designations from the U.S. Food and Drug Administration for NBI-921352 in SCN8A-DEE. The company intends to initiate a Phase II study of NBI-921352 in patients with SCN8A-DEE in the second half of 2021. For more information about the intended study, please visit clinicaltrials.gov.


Focal-onset or partial seizures are limited to one area of the brain and are the most common form of seizures in adults. Focal-onset seizures last for 1–2 minutes and can involve involuntary movements and be associated with lack of awareness. Neurocrine Biosciences plans to initiate a Phase II study of NBI-921352 in patients with focal-onset seizures in 2021.