Abstract Details

Title Interim Long-term Safety and Efficacy of XEN1101, a Potent, Selective Potassium Channel Opener: Update from an Ongoing Open-label Extension of a Phase 2b Study (X-TOLE) in Adults with Focal Epilepsy

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S19 - Epilepsy Clinical Trials and Long-term Studies (4:18 PM-4:30 PM)

Poster/Presentation
Number 005

Background In the double-blind period (DBP) of X-TOLE, XEN1101 (10, 20, and 25 mg QD with food) showed a dose-dependent, statistically significant, and rapid-onset reduction in seizure frequency. We report interim 18-month OLE safety and efficacy data.

Objective To report interim 18-month data from an ongoing, long-term, open-label extension (OLE) of a Phase 2b study (X-TOLE) of XEN1101 in adults with focal onset seizures (FOS).

Design/Methods Eligible patients enrolled in the 5-year OLE at 20 mg QD with food. Assessments occurred at week 3 in the OLE and at 3-month intervals thereafter. Safety assessments included treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs). Primary efficacy outcome was median percentage change (MPC) in monthly (28-day) FOS frequency from DBP baseline.

Results 285 patients completed the DBP and 275 (96.5%) enrolled in the OLE. At the 18-month OLE interim analysis (April 12, 2023), 182 had been treated for ≥1 year and 170 for ≥18 months; 159 (57.8%) patients continued participation. The majority of TEAEs were mild or moderate. The most common TEAEs were dizziness, coronavirus infection, headache, fall, and somnolence. 20.7% reported TEAEs leading to dose reduction. In the OLE at 1 and 1.5 years, the mean (SD) weight gain was 1.1 (5.9) kg and 0.5 (7.1) kg, respectively. SAEs were reported in 33 (12%) patients, 6 patients (2.2%) reported treatment-related SAEs. One SAE led to death (sudden unexpected death in epilepsy, considered not treatment related). The MPC was –83.4% at 18 months in the OLE vs DBP baseline. Updated safety and efficacy analyses will be presented.

Conclusions XEN1101 was generally well tolerated and demonstrated an OLE safety profile similar to that seen in the DBP and other antiseizure medications used in FOS treatment. No new safety signals emerged. These promising data suggest long-term efficacy of XEN1101 in a difficult-to-treat population.

Authors/Disclosures
Jacqueline French, MD, FAAN (NYU Comprehensive Epilepsy Ctr) PRESENTER	Dr. French has received personal compensation in the range of $50,000-$99,999 for serving as an officer or member of the Board of Directors for Epilepsy Foundation. The institution of Dr. French has received research support from Epilepsy Study Consortium/ Epilepsy Foundation (Funded by UCB). The institution of Dr. French has received research support from GW/One8 Foundation/FACES. The institution of Dr. French has received research support from NINDS. The institution of Dr. French has received research support from Xenon. The institution of Dr. French has received research support from Cerevel. The institution of Dr. French has received research support from FACES. The institution of Dr. French has received research support from UCB. The institution of Dr. French has received research support from Epilepsy Study Consortium. The institution of Dr. French has received research support from UCB. Dr. French has received personal compensation in the range of $100,000-$499,999 for serving as a Chief Medical/Innovation Officer with Epilepsy Foundation. Dr. French has a non-compensated relationship as a Consultant with Angelini that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Alterity Therapeutics Limited that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Bright minds Biosciences that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Cerecin Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Cognizance Biomarkers that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Arvelle that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Beacon biosignals that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, Advisory Board with Biohaven Pharmaceuticals that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Bloom Science Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with BridgeBio Pharma Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant, scientific advisory board with Camp4 Therapeutics Corporation that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, Scientific Advisory Board with Cerebral Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Cerevel that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a SAB with Coda Biotherapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Genentech Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Crossject that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Eisai, that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Eliem Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Encoded Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with iQure Pharma that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, SAB with Engrail that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a SAB with Epihunter that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a SAB with Epiminder that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Epitel Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Equilibre BioPharmaceuticals that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Greenwich Biosciences that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Grin Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with GW Pharma that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Janssen Pharmaceutica that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Jazz Pharmaceuticals that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Knopp Biosciences that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Lipocine that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with LivaNova that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Longboard Pharmaceuticals that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, SAB with Lundbeck that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, SAB with Marinus that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Modulight Bio that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Leal therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Neumirna Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant,SAB with Neurocrine that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Neuroelectrics USA Corporation that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Neuronetics Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Ono Pharmaceutical Co that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, SAB with Otsuka Pharmaceutical Development that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, SAB with Ovid Therapeutics Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Paladin Labs Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Rapport Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Praxis that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with PureTech LTY Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with SK Life Sciences that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Stoke that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Supernus that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Takeda that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant, SAB with UCB Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Ventus Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consulting, steering committee with Xenon that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consultant with Korro Bio Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with NeuroPro Therapeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Advisory board with Receptor that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Advisory board with Sage Therpeutics that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Advisory Board with Third Rock Ventures that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consultant with Vida Ventures Management that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consulting with Pfizer that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consulting with Agrithera, Inc that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a consulting with Autifony therapeutics, Unlimited that is relevant to AAN interests or activities. Dr. French has a non-compensated relationship as a Consulting with Baergic Bio that is relevant to AAN interests or activities.
Roger J. Porter, MD, FAAN	Dr. Porter has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Xenon. Dr. Porter has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Neurocrine. Dr. Porter has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Longboard. Dr. Porter has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Engrail. Dr. Porter has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Axonis. Dr. Porter has received publishing royalties from a publication relating to health care.
Emilio Perucca	No disclosure on file
Martin Brodie	No disclosure on file
Michael A. Rogawski, MD, PhD (University of California - Davis)	Dr. Rogawski has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Xenon Pharmaceuticals.
Cynthia L. Harden, MD (Xenon Pharmaceuticals Inc)	Dr. Harden has received personal compensation for serving as an employee of Xenon Pharmaceuticals Inc.. Dr. Harden has stock in Xenon Pharmaceuticals Inc.. Dr. Harden has received intellectual property interests from a discovery or technology relating to health care.
Jenny Qian	No disclosure on file
Constanza Luzon	Constanza Luzon has received personal compensation for serving as an employee of Xenon Pharmaceuticals Inc.. Constanza Luzon has stock in Xenon Pharmaceuticals.
Christopher Kenney	No disclosure on file
Gregory N. Beatch, PhD	Dr. Beatch has received personal compensation for serving as an employee of Xenon Pharmaceuticals Inc. Dr. Beatch has stock in Xenon Pharmaceuticals Inc. Dr. Beatch has received intellectual property interests from a discovery or technology relating to health care.