SK Biopharm's cenobamate wins Japan approval, completing Northeast Asia regulatory sweep

SK Biopharm's cenobamate, an innovative epilepsy drug, has received marketing approval in Japan, completing the company's entry into all three major Northeast Asian markets — South Korea, China and Japan.

SK Biopharm announced Wednesday that its local partner Ono Pharmaceutical had obtained manufacturing and marketing approval from Japan's Ministry of Health, Labour and Welfare for cenobamate, sold in Japan under the brand name Excopri.

Japan is the world's second-largest epilepsy market by country after the United States, with an estimated 1 million patients — roughly 30 percent of whom are considered treatment-resistant, meaning existing medications fail to control their seizures. The approval was based on results from a multinational Phase 3 trial (YKP3089C035) conducted in South Korea, China and Japan. The trial demonstrated a statistically significant reduction in seizure frequency compared with placebo, along with an acceptable safety profile, in adults with treatment-resistant focal seizures.

With this approval, SK Biopharm has cleared the regulatory bar in all three Northeast Asian countries. The company had previously received marketing approvals in South Korea in November 2025 and in China in December 2025, with commercial prescriptions in China beginning in March this year. In Japan, Ono Pharmaceutical secured final approval roughly a year after submitting its new drug application in September 2025.

Under a technology licensing agreement signed with Ono Pharmaceutical in October 2020, SK Biopharm will receive a milestone payment tied to this approval and will earn tiered royalties on future local sales. The size of the milestone payment has not been disclosed under the terms agreed by both parties.

Cenobamate has now received marketing approval in more than 45 countries, including the United States and across Europe. In the US, SK Biopharm operates a direct sales operation, while in Asia and Europe it pursues a two-track strategy pairing direct sales in key markets with partnerships with established local pharmaceutical companies. Ono Pharmaceutical is currently running separate Phase 3 trials in Japan for adolescent and adult patients with primary generalized tonic-clonic seizures and for pediatric patients with focal seizures.

The Japanese approval marks a turning point that strengthens SK Biopharm's global cash-generating capacity — adding a stable royalty pipeline across Asia through licensing partners, anchored by the world's second-largest single-country epilepsy market, on top of the direct-sales revenue the company maximizes in the United States.

"Japan is a strategic market we must secure to drive cenobamate's global expansion," SK Biopharm President Lee Dong-hoon said. "Now that we have completed our Northeast Asian foothold connecting South Korea, China and Japan, we will focus on delivering full commercial results by expanding local prescriptions."