Xenon Pharmaceuticals Inc. announced that its collaboration to develop treatments for epilepsy with Neurocrine Biosciences, Inc. achieved a regulatory milestone with the approval of a clinical trial application (CTA) in Europe, triggering an aggregate payment of $10.0 million to Xenon. Xenon has an ongoing collaboration 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 with potential in SCN8A developmental and epileptic encephalopathy (SCN8A-DEE) and other forms of epilepsy.

The FDA has provided feedback on an Investigational New Drug (IND) application submitted by Neurocrine Biosciences in support of a Phase 2 clinical trial in SCN8A-DEE patients. Based on this feedback, Neurocrine Biosciences anticipates initiating a Phase 2 clinical trial in adolescent patients (aged 12 years and older) with SCN8A-DEE in the second half of 2021, and the trial protocol will be amended to include younger pediatric patients (aged 2-11 years) with SCN8A-DEE as soon as the FDA has reviewed and approved additional non-clinical information. Upon FDA acceptance of a protocol amendment for NBI-921352 in pediatric patients (aged 2-11 years) with SCN8A-DEE, Xenon is eligible to receive an aggregate payment of $15.0 million in the form of 45% cash and a 55% equity investment in Xenon at a 15% premium to Xenon's 30-day trailing volume weighted average price at that time.

In parallel, Neurocrine Biosciences is advancing clinical plans to develop NBI-921352 for the treatment of focal-onset seizures in adults and expects to initiate a Phase 2 clinical trial in 2021.