Name: Azetukalner (XEN1101) in Focal onset seizures: Expected outcomes of therapy
Published: 2026-09-21T21:41:53-04:00

Goal of antiseizure therapy

“The goal of epilepsy therapy is the complete elimination of seizures; however, this is not achievable in about one-third of patients.” (opens the source at this quote in a new tab)

Operational definition of seizure freedom

“seizure freedom (Category 1 outcome) is defined as freedom from seizures for a minimum of three times the longest preintervention interseizure interval (determined from seizures occurring within the past 12 months) or 12 months, whichever is longer.” (opens the source at this quote in a new tab)
“It is proposed as a testable hypothesis that drug resistant epilepsy is defined as failure of adequate trials of two tolerated, appropriately chosen and used antiepileptic drug schedules (whether as monotherapies or in combination) to achieve sustained seizure freedom.” (opens the source at this quote in a new tab)

Clinically accepted benchmark used by the manufacturer

“The clinically accepted definition of seizure freedom is no seizures for at least 12 months.” (opens the source at this quote in a new tab)

What constitutes unsuccessful treatment

“Treatment is unsuccessful if it does not reduce or stop seizures, or if side effects are intolerable for the person with epilepsy.” (opens the source at this quote in a new tab)

The responder endpoint used in adjunctive trials

“Another widely used efficacy endpoint for evaluating ASM efficacy is the percentage of patients with a ≥50% reduction in seizure frequency during a given treatment period compared with baseline, known as the RR50.” (opens the source at this quote in a new tab)

Seizure freedom rather than seizure reduction drives quality of life

“In this study, HRQOL improvement occurred primarily among patients who achieved complete seizure freedom.” (opens the source at this quote in a new tab)
“Many AED trials use a 50% seizure-frequency reduction criterion as a trial end point, but measurable impacts of this degree of reduction in seizure frequency on HRQOL in this sample were not observed.” (opens the source at this quote in a new tab)
“No significant change in QOLIE-31 and QOLIE-89 overall scores was observed for subjects who did not achieve seizure freedom.” (opens the source at this quote in a new tab)
“These results further support striving for seizure freedom as an epilepsy care goal.” (opens the source at this quote in a new tab)

Statistical limitations of the 50 percent responder criterion

“We showed that individual variance in monthly seizure rates can lead to an unacceptably high false-positive rate in the detection of individual treatment responders.” (opens the source at this quote in a new tab)
“This finding suggests that some drugs may be incorrectly evaluated as effective; or, conversely, that helpful drugs could be rejected based on 50% response rates.” (opens the source at this quote in a new tab)

Seizure control and sudden unexpected death in epilepsy

“Clinicians should inform persons with epilepsy that seizure freedom, particularly freedom from GTCS, is strongly associated with decreased SUDEP risk.” (opens the source at this quote in a new tab)