Xenon Pharmaceuticals Announces Publication of Results from XEN1101 Phase 2b “X-TOLE” Clinical Trial in Peer-Reviewed Journal Article in JAMA Neurology

VANCOUVER, British Columbia, Oct. 09, 2023 (GLOBE NEWSWIRE) -- Xenon Pharmaceuticals Inc. (Nasdaq:XENE), a neurology-focused biopharmaceutical company, today announced the medical journal JAMA Neurology has published peer-reviewed efficacy and safety results from the X-TOLE Phase 2b randomized clinical trial of XEN1101, a novel potassium channel opener, in adults with focal epilepsy. Importantly, the efficacy and safety findings of this clinical trial supported the further clinical development in epilepsy of XEN1101, which is currently being evaluated in Phase 3 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 2b X-TOLE study of XEN1101 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, XEN1101 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 3 development of XEN1101 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 XEN1101 Phase 2b 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 XEN1101 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. XEN1101 was generally well tolerated and TEAEs were similar to those of commonly prescribed ASMs, and no TEAEs leading to death were reported.