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XEN1101

Phase 3

Focal Epilepsy | Small molecule | Neurology |Xenon Pharmaceuticals Inc.|Last Updated: May 14, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials2
Total Enrollment1,205
FDA Designations
No designations recorded
Clinical Trials (2)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT05718817An Open-label Study of XEN1101 in EpilepsyPHASE3 ENROLLING BY_INVITATION 880 — — Apr 25, 2023Jun 1, 2033May 14, 2026149 United States, Argentina +22
NCT03796962A Study to Evaluate XEN1101 as Adjunctive Therapy in Focal EpilepsyPHASE2 ACTIVE NOT_RECRUITING 325 — — Jan 30, 2019Oct 1, 2028Sep 24, 202495 United States, Canada +7
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Study Endpoints
Primary Endpoints
The adverse events
From the start of treatment in the open-label extension (OLE) study through 8 weeks after the last dose.

To assess the safety and tolerability of XEN1101

Median Percent Change in Focal Seizure Frequency
From baseline (8 weeks prior to Day 0) through to the final dose (up to Day 56)

Median percent change in monthly (28 days) focal seizure frequency from baseline to DBP for XEN1101 versus placebo

Secondary Endpoints
Change in monthly seizure rate
From baseline through the active extension treatment (Week 312).
Proportion of responders
From baseline through the active extension treatment (Week 312).
Change in Clinical Global Impression of Severity (CGI-S)
From baseline through the active extension treatment (Week 312).
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Study Design & Arms
AllocationNA
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
XEN1101 15 or 25 mg/dayEXPERIMENTALXEN1101 15 or 25 mg/day
25 mg XEN1101EXPERIMENTALCapsule filled with 25 mg XEN1101
20 mg XEN1101EXPERIMENTALCapsule filled with 20 mg XEN1101
10 mg XEN1101EXPERIMENTALCapsule filled with 10 mg XEN1101
PlaceboPLACEBO_COMPARATORPlacebo capsule
Interventions
NameTypeDescription
XEN1101DRUGXEN1101 capsules
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Eligibility Criteria
Age Range12 Years — N/A
SexALL
Healthy VolunteersNo
Study Sites149

Inclusion Criteria: 1. Subject must be properly informed of the nature and risks of the study and give informed consent in writing prior to entering the study (for adult subjects) and for adolescent subject's parent/legal guardian and subject gives informed consent or assent in writing prior to ent...

Countries:United StatesArgentinaAustraliaAustriaBelgiumBulgariaCanadaChileCroatiaCzechiaFinlandFranceGeorgiaGermanyHungaryIrelandIsraelItalyMexicoNew ZealandPolandPortugalSpainUnited KingdomMoldovaUkraine
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Recent Changes (Last 90 Days)
MEDIUMMay 26, 2026NCT05718817primaryCompletionDate: changed
LOWMay 26, 2026NCT03796962primaryCompletionDate: changed
LOWMay 24, 2026NCT05718817studyFirstPostDate: changed
LOWMay 24, 2026NCT03796962studyFirstPostDate: changed