Rare Daily Staff

Neurocrine Biosciences and Xenon Pharmaceuticals said they have entered into a multi-year research collaboration to discover and develop first-in-class treatments for epilepsy, including Xenon’s experimental treatment for a rare form of epilepsy.

Neurocrine Biosciences will pay Xenon $50 million upfront in cash and equity for an exclusive license to XEN901, a clinical stage selective Nav1.6 sodium channel inhibitor with potential in SCN8A developmental and epileptic encephalopathy and other forms of epilepsy, including focal epilepsy.

Neurocrine also gains an exclusive license to develop preclinical compounds, including selective Nav1.6 inhibitors and dual Nav1.2/1.6 inhibitors. The agreement also includes a multi-year research collaboration to discover, identify and develop additional novel Nav1.6 and Nav1.2/1.6 inhibitors.

SCN8A-related epilepsy with encephalopathy is a condition characterized by recurrent seizures (epilepsy), abnormal brain function (encephalopathy), and intellectual disability. The signs and symptoms of this condition typically begin in infancy. It is caused by mutations in the SCN8A gene, which provides instructions for making one part of a sodium channel called Nav1.6 that plays a key role in the ability of neurons to communicate by generating and transmitting electrical signals. The mutations cause the channel to remain open, increasing electrical signals and neuronal activity that lead to seizures in people with SCN8A-related epilepsy with encephalopathy.

Other signs and symptoms of SCN8A-related epilepsy with encephalopathy include intellectual disability that may be mild to severe and problems with movement. In rare cases, individuals with this condition die unexpectedly for no known reason.

XEN901 is a potent, highly selective Nav1.6 sodium channel inhibitor being developed to treat pediatric patients with SCN8A developmental and epileptic encephalopathy and other potential indications, including adult focal epilepsy.

“With its proven expertise in developing and commercializing treatments for neurological disorders, we believe Neurocrine Biosciences is an ideal partner to maximize the potential value of XEN901 for patients,” said Simon Pimstone, CEO of Xenon. “Importantly, this collaboration represents a significant investment in XEN901 and Xenon’s earlier-stage Nav1.6 and Nav1.2/1.6 inhibitor programs and allows for a broader development of these promising compounds than we could accomplish independently.”

Under the terms of their agreement, Xenon is eligible for up to $1.7 billion in development, regulatory, and commercial milestone payments related to XEN901 and other licensed products, plus royalties. Neurocrine Biosciences will be responsible for development costs associated with the programs and will also fund a research collaboration up to three years. Xenon retains an option to co-fund 50 percent of the U.S. development costs of XEN901 and another product candidate in exchange for increased U.S. royalties.

Neurocrine Biosciences anticipates filing an IND application with the U.S. Food and Drug Administration in the middle of 2020 in order to start a proposed clinical trial for XEN901 in patients with SCN8A developmental and epileptic encephalopathy, and will pay Xenon up to $25 million upon FDA acceptance of the IND.

Photo: Simon Pimstone, CEO of Xenon

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