Xenon Pharmaceuticals Inc. announced a summary of its oral and poster presentations at the 35th International Epilepsy Congress (IEC) taking place in Dublin, Ireland from September 2-6, 2023. An interim analysis (cutoff date September 22, 2022) of the ongoing X-TOLE open-label extension (OLE) study demonstrated that treatment with XEN1101 resulted in sustained monthly reduction in seizure frequency from double-blind period (DBP) baseline, with adverse events (AEs) consistent with previous results and those seen with other antiseizure medications (ASMs), and no new safety signals were identified. Newly compiled interim data from the X-TOLE OLE focused on quality-of-life (QoL) measures as assessed using a validated tool called the Quality of Life in Epilepsy Inventory-31 (QOLIE-31) in the overall OLE group as well as a subgroup that was seizure-free (SFG) for at least 12 consecutive months at the time of the interim data analysis.

The SFG consisted of 29 patients (approximately 10.5% of those enrolled in the OLE). The overall OLE patient group showed improvements in overall Quality of Life; Clinically important improvements in QOLIE-31 subscales of Seizure Worry, Social Functioning, and Medication Effects were seen across all patients, with even greater improvements in the SFG; The SFG achieved clinically important improvements in all QoL subscales assessed by the QOLIE-31; The improvements in Medication Effects across all patients is notable as this measures the patients? perception of drug tolerability as well as the benefit of long-term seizure reduction.

On September 3, 2023, Xenon hosted the following presentations at IEC 2023: Poster: Quality-of-Life Improvements in Adults With Focal Onset Seizures Treated With XEN1101 in an Ongoing, Long-Term, Open-Label Extension of a Phase 2b Study (X-TOLE). Poster: XEN1101, a Novel Potassium Channel Modulator: Interim Data From an Ongoing, Long-Term, Open-Label Extension of a Phase 2b study (X-TOLE) in Adults With Focal Epilepsy. Oral Presentation: Design of Two Parallel Randomized, Double-Blind, Placebo-Controlled Phase 3 Studies to Evaluate the Safety and Efficacy of XEN1101 as Adjunctive Therapy in the Treatment of Focal Onset Epilepsy.

Oral Presentation: A Randomized, Double-Blind, Placebo-Controlled, Phase 3 Study to Evaluate the Safety and Efficacy of XEN1101 as an Adjunctive Therapy in the Treatment of Primary Generalized Tonic-Clonic Seizures.