XEN901 for Epilepsy

XEN901 is a potent, highly selective Nav1.6 sodium channel inhibitor being developed for the treatment of epilepsy. By selectively targeting NaV1.6, it is anticipated that XEN901 may achieve efficacy conferred by this well-validated epilepsy target, but with a potentially improved therapeutic index compared with currently available non-selective sodium channel inhibitors.

At the American Epilepsy Society (AES) Annual Meeting in December 2018, Xenon presented pre-clinical research related to XEN901 in a number of posters, which can be found on our “Publications” page under the XEN901 heading. 

Clinical Development

In February 2018, following acceptance of our CTA for XEN901 by the MHRA in the United Kingdom, we initiated a randomized, double-blind, placebo-controlled Phase 1 clinical trial to evaluate XEN901’s safety, tolerability and pharmacokinetics in both SAD and MAD cohorts of approximately 64 healthy subjects in total. 

We announced interim results from the XEN901 Phase 1 clinical trial and the related pilot TMS study at the AES Annual Meeting in December 2018 in a poster entitled “A First in Human Phase 1 Study to Assess the Safety, Tolerability and Pharmacokinetics of a Novel Nav1.6 Selective Small Molecule Sodium Channel Inhibitor (XEN901) in Healthy Subjects.”

The next steps for XEN901 include completing the Phase 1 clinical trial and continued planning for Phase 2 clinical development evaluating XEN901 as a treatment for adult focal seizures or for rare, pediatric forms of epilepsy, including SCN8A gain-of-function epilepsy patients, depending on feedback from planned discussions with regulatory agencies. Xenon expects to receive regulatory feedback on advancing XEN901 directly into pediatric SCN8A gain-of-function epilepsy patients in the second quarter of 2019, and pediatric formulation development and juvenile toxicology studies are underway.

About Early Infantile Epileptic Encephalopathy (EIEE13)

Mutations in the SCN8A gene result in a gain-of-function in the NaV1.6 sodium channel that can cause a rare, extremely severe, single-gene epilepsy disorder known as EIEE13, which typically presents with seizure onset between birth and 18 months of age. Most children diagnosed with EIEE13 have seizures that can occur multiple times a day and are often difficult to treat. Other symptoms include learning difficulties, muscle spasms, low or high muscle tone, poor coordination, developmental delay, and features similar to autism. The extent of physical disability leaves some children able to make little or no voluntary movement. Most children will have trouble learning to speak, and some will need assistance from feeding tubes to get the nourishment they need to grow.