Publication of results from XEN 1101 phase IIb “X-TOLE” clinical trial in peer-reviewed journal article in JAMA Neurology

Importantly, the efficacy and safety findings of this clinical trial supported the further clinical development in epilepsy of XEN 1101, which is currently being evaluated in Phase III clinical trials in patients with focal onset seizures (FOS) and primary generalized tonic-clonic seizures.

Mr. Ian Mortimer, Xenon’s President and Chief Executive Officer, stated, “We are pleased to report that the peer-reviewed results from our Phase IIb X-TOLE study of XEN 1101 in adults with focal epilepsy have been published in the prestigious JAMA Neurology journal. With a cohort of patients now on drug for more than four years as we continue to gather data from our ongoing open-label extension study, XEN 1101 continues to demonstrate its efficacy through sustained seizure reduction and a compelling product profile with once-daily dosing with food and no titration required. Based on the need for new, efficacious, and well-tolerated antiseizure medications, we continue to advance the Phase III development of XEN 1101 in our X-TOLE2, X-TOLE3 studies (in focal onset seizures) and the X-ACKT study (in primary generalized tonic-clonic seizures). We look forward to presenting additional longer-term data from the X-TOLE open-label extension study at AES 2023, the upcoming annual meeting of the American Epilepsy Society in December.”

In the XEN 1101 Phase IIb X-TOLE study , the primary efficacy endpoint was the median percent change from baseline in monthly FOS frequency. Treatment-emergent adverse events (TEAEs) were recorded, and comprehensive laboratory assessments were made. A total of 325 patients who were randomized and treated were included in the safety analysis; 285 completed the 8-week double-blind phase. In the 325 patients included, mean (SD) age was 40.8 (13.3) years, 168 (51.7%) were female, and 298 (91.7%) identified their race as White. Treatment with XEN 1101 was associated with seizure reduction in a robust dose-response manner. The median (IQR) percent reduction from baseline in monthly FOS frequency was 52.8% (P < .001 vs placebo; IQR, -80.4% to -16.9%) for 25 mg, 46.4% (P < .001 vs placebo; IQR, -76.7% to - 14.0%) for 20 mg, and 33.2% (P = .04 vs placebo; IQR, - 61.8% to 0.0%) for 10 mg, compared with 18.2% (IQR, -37.3% to 7.0%) for placebo. XEN 1101 was generally well tolerated and TEAEs were similar to those of commonly prescribed ASMs, and no TEAEs leading to death were reported.

See-"Efficacy and Safety of XEN 1101, a Novel Potassium Channel Opener, in Adults With Focal Epilepsy A Phase IIb Randomized Clinical Trial". Jacqueline A. French, MD; Roger J. Porter, MD; Emilio Perucca, MD, PhD,; et al. JAMA Neurol. Published online October 9, 2023. doi:10.1001/jamaneurol.2023.3542.