SK Biopharmaceutical’s Xcopri (cenobamate) met the bar in a phase 3 trial that could support the company’s ambitions of building a blockbuster with an expansion into another seizures subtype.
The South Korean pharma won FDA approval for Xcopri in 2019 as a treatment for partial-onset seizures, also known as focal seizures, in adults. Since then, with rapid global growth, SK has outlined blockbuster ambitions for the drug by 2029.
Now, with a positive phase 3 trial, another indication for primary generalized tonic-clonic (PGTC) seizures could be on the table.
In its phase 3 study, SK evaluated Xcopri in 169 adult and adolescent patients with PGTC seizures, finding a “statistically significant reduction” in the seizures, the company said in a filing on the Korea Exchange. Specifically, seizure frequency from baseline levels was reduced by 71.9% in the Xcopri-treated group and 39.6% in the placebo arm over 28-day intervals.
PGTC seizures are the most common type of generalized seizures—which are less prevalent than focal seizures—and considered the most severe due to the high risk of seizure-related injury and sudden unexpected death in epilepsy, SK pointed out. With limited treatment options, the company hopes Xcopri can address an unmet need and contribute to quality-of-life improvements for epilepsy patients, it said.
While the current treatment landscape for the seizure type is sparse and generally made up of antiseizure medications such as GSK’s off-patent Lamictal, SK isn’t the only one looking to edge in on the market. Xenon Pharmaceuticals is approaching an early 2026 phase 3 readout of its lead candidate, azetukalner, in focal seizures as an additional phase 3 trial in PGTC seizures continues.
According to a note by Jefferies analysts, SK’s win in PGTC seizures “serves as a reminder” that Xenon’s azetukalner could show “broad-spectrum activity” as well, supporting peak sales expectations of $400 million from that indication alone and $1 billion on the focal seizures side.
However, SK still has some breathing room from the competition as the analysts note that SK’s study took seven years to produce top-line data after its 2018 start, suggesting that Xenon’s phase 3 could take “several years” as well.
SK will file for a label expansion with the FDA and present additional analysis from the study at the American Epilepsy Society Annual Meeting in December. Last quarter, Xcopri helped the company reach record sales with U.S. revenues of $111 million.