NBI-921352 (Partnered Program with Neurocrine Biosciences, Inc.)

In December 2019, we entered into a license and collaboration agreement with Neurocrine Biosciences to develop treatments for epilepsy. Neurocrine Biosciences has an exclusive license to XEN901, now known as NBI-921352, a clinical stage selective Nav1.6 sodium channel inhibitor, and an exclusive license to pre-clinical compounds for development, including selective Nav1.6 inhibitors and dual Nav1.2/1.6 inhibitors. The agreement also included a multi-year research collaboration to discover, identify and develop additional novel Nav1.6 and Nav1.2/1.6 inhibitors.

NBI-921352 is a potent, highly selective Nav1.6 sodium channel inhibitor being developed to treat pediatric patients with SCN8A developmental and epileptic encephalopathy, or SCN8A-DEE, and other potential indications, including adult focal epilepsy.

Clinical Development

The U.S. Food and Drug Administration (FDA) provided feedback on an Investigational New Drug (IND) application submitted by Neurocrine Biosciences in support of a Phase II clinical trial in pediatric SCN8A-DEE patients. As part of its review of the IND, the FDA is requesting additional non-clinical data to support dose justification in this pediatric study. Neurocrine Biosciences and Xenon will engage with the FDA to address the feedback received with the goal of initiating a Phase II clinical trial in 2021. In parallel with this interaction, Neurocrine Biosciences is advancing clinical plans to develop NBI-921352 for the treatment of adult focal epilepsy. In addition, the FDA recently granted Rare Pediatric Disease Designation for NBI-921352 for the treatment of SCN8A-DEE.

Pursuant to the collaboration agreement, upon FDA acceptance of an IND for NBI-921352 in either SCN8A-DEE or another major indication, Xenon is eligible to receive a milestone payment of either $25 million or $10 million, respectively, with 55% of the amount in the form of an equity investment in Xenon at a 15% premium to Xenon’s 30-day trailing volume weighted average price at that time.