Xenon Pharmaceuticals Inc. announced that its collaboration to develop treatments for epilepsy with Neurocrine Biosciences, Inc. achieved a regulatory milestone, which has triggered an aggregate payment of $15.0 million to Xenon. The U.S. Food and Drug Administration (FDA) accepted Neurocrine's protocol amendment that expands the study population to include subjects aged between 2 and 11 years in the ongoing Phase 2 randomized, double-blind, placebo-controlled study to evaluate the efficacy, safety, tolerability, and pharmacokinetics of NBI-921352 in pediatric patients with SCN8A developmental and epileptic encephalopathy (SCN8A-DEE). Pursuant to the agreement, Xenon will receive an aggregate of $15.0 million from Neurocrine Biosciences in the form of a $6.75 million payment in cash and a $8.25 million equity investment at a Xenon per share price of $31.855, calculated as a 15% premium to Xenon's 30-day trailing volume weighted average price.

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 selective Nav1.6 sodium channel inhibitor. Neurocrine Biosciences is conducting a Phase 2 clinical trial evaluating NBI-921352 in adult patients with focal-onset seizures, with data expected in 2023.

In addition, a Phase 2 clinical trial is underway evaluating NBI-921352 in pediatric patients (aged between 2 and 21 years) with SCN8A-DEE. Pursuant to the terms of the agreement, Xenon has the potential to receive certain clinical, regulatory, and commercial milestone payments, as well as future sales royalties.