SK Submits sNDA for Cenobamate (XCOPRI) in PGTC

SK Biopharmaceuticals has submitted a supplemental New Drug Application (sNDA) to the U.S. Food and Drug Administration (FDA), seeking approval of cenobamate (XCOPRI) for the treatment of primary generalized tonic-clonic (PGTC) seizures in patients aged 12 years and older. The November 4, 2026, submission is supported by results from a global Phase 3 trial demonstrating a statistically significant reduction in seizure frequency compared with placebo.

The company also submitted a separate sNDA in October 2026 seeking to extend cenobamate’s existing focal-onset seizure (FOS) indication to pediatric patients. Both applications are part of the company’s efforts to expand cenobamate’s use beyond its currently approved U.S. indication for partial-onset seizures in adults aged 18 years and older.

Phase 3 Trial Demonstrates Reduction in PGTC Seizures

The PGTC application is supported by a global Phase 3 trial (NCT03678753), which enrolled 169 patients aged 12 years and older across 122 clinical sites in 12 countries.

The randomized, double-blind, placebo-controlled study evaluated cenobamate as an adjunctive treatment administered alongside patients’ existing antiseizure medications. The trial included a 10-week dose-titration period followed by a 12-week maintenance period.

Key findings included:

• Efficacy: Cenobamate achieved a median 71.9% reduction in PGTC seizure frequency from baseline, compared with a 39.6% reduction in the placebo group. The difference was statistically significant (p=0.003).
• Safety: Most reported adverse events were mild to moderate. The safety findings were consistent with cenobamate’s established profile, with no new safety signals observed, according to the company.

These results provide the clinical basis for the PGTC sNDA. If approved, cenobamate would offer an additional treatment option for patients aged 12 years and older with this seizure type.

Pediatric Development and Oral Suspension Formulation

SK Biopharmaceuticals is pursuing two additional regulatory developments alongside the PGTC indication expansion.

• Pediatric FOS (October 2026 sNDA): The application seeks to extend cenobamate’s existing focal-onset seizure indication to pediatric patients. The company said clinical trials supported the treatment’s safety in children with FOS, although the announcement did not disclose the proposed age range or provide specific pediatric efficacy results.
• Oral Suspension (March 2026 NDA): The company submitted a separate NDA for an investigational oral suspension formulation intended for adults with focal seizures who have difficulty swallowing tablets. The formulation was also used in the pediatric clinical development programme.

The FDA accepted the oral suspension NDA for review in June 2026 and assigned a Prescription Drug User Fee Act (PDUFA) target action date of January 31, 2027. Unlike the indication-expansion applications, this submission focuses on an alternative formulation rather than a new seizure-type indication.

Commercial and Global Context

Cenobamate was launched in the U.S. in 2020 for the treatment of partial-onset seizures in adults. Outside the U.S., it is approved in the European Union and United Kingdom, where it is marketed as ONTOZRY, with regulatory approvals in more than 45 countries and regions through regional partnerships.

Donghoon Lee, CEO of SK Biopharmaceuticals, described the PGTC submission as an important step in the company’s continued investment in cenobamate. He highlighted the development programme’s focus on additional seizure types, age groups and formulations to address the diverse needs of people living with epilepsy.

Regulatory Outlook

The November announcement did not disclose FDA review timelines or anticipated decision dates for the PGTC and pediatric FOS sNDAs. The oral suspension NDA, however, is under FDA review with a PDUFA target action date of January 31, 2027.

Until the proposed indication expansions receive FDA approval, XCOPRI’s approved U.S. indication remains limited to partial-onset seizures in adults aged 18 years and older. The oral suspension formulation also remains investigational pending regulatory approval.

Reference

SK Biopharmaceuticals Submits Supplemental New Drug Application to U.S. FDA for Cenobamate, SK Biopharmaceuticals, 04 November 2026

Randomized, Double-Blind Study to Evaluate Efficacy and Safety of Cenobamate Adjunctive Therapy in PGTC Seizures, ClinicalTrials.gov ID NCT03678753