Xenon Pharmaceuticals Inc. 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. In the XEN1101 Phase 2b X-TOLE study, the primary efficacy endpoint was the median percentage 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) percentage reduction from baseline in monthly FOS frequency was 52.8% (P < 0.001 vs placebo; IQR, -80.4% to -16.9%) for 25 mg, 46.4% (P < 0.001 vs placebo; IQR, -76.7% to -14.0%) for 20 mg, and 33.2% (P = 0.04 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.