SK Biopharmaceuticals to In-License Opakalim for Epilepsy Treatment

SK Biopharmaceuticals has agreed to in-license opakalim, an investigational anti-seizure medicine from Biohaven, in a deal that could reach $795 million and could help the South Korean drugmaker expand its epilepsy portfolio.

Under the agreement, SK Biopharmaceuticals will pay $400 million in upfront cash, including $350 million at closing and another $50 million one year later. The deal also includes up to $395 million in development and regulatory milestone payments. Royalties will be paid separately, with a portion of the milestone and royalty payments going to Knopp Biosciences, the original developer of opakalim.

The transaction is subject to required antitrust approvals and other standard closing conditions.

Opakalim is a selective Kv7 potassium channel activator being developed as a treatment for epilepsy. The drug is currently being studied in Phase 2/3 clinical trials for adults with partial-onset seizures. SK Biopharmaceuticals expects initial top-line results from the RISE 3 trial by the end of 2026, followed by another data readout in 2028.

If development and regulatory plans remain on track, SK Biopharmaceuticals aims to launch opakalim in the United States as early as 2029.

Once the transaction closes, SK Biopharmaceuticals will receive exclusive global development and commercialization rights to opakalim. The agreement also gives the company access to Biohaven’s Kv7 discovery platform and related compounds, potentially allowing SK Biopharmaceuticals to expand its pipeline with additional Kv7-targeting medicines.

The deal is part of SK Biopharmaceuticals’ strategy to move beyond its current single-commercial-product model. The company already markets cenobamate, sold in the United States as XCOPRI, for epilepsy.

SK Biopharmaceuticals plans to use its existing U.S. commercial infrastructure to support a potential launch of opakalim. Through its U.S. subsidiary, SK Life Science, the company has built an epilepsy-focused commercial organization with more than 150 neurology field professionals and established relationships with epilepsy centers and neurologists.

The company expects the combination of cenobamate and opakalim to give it two different treatment options for epilepsy. While cenobamate is already an established commercial product, opakalim is being developed with a different mechanism and is intended to provide another option for patients with partial-onset seizures.

Biohaven CEO Vlad Coric said opakalim is designed as a selective Kv7.2/7.3 activator with the potential to provide seizure control while limiting central nervous system side effects such as sedation and dizziness.

For SK Biopharmaceuticals, the agreement marks a significant step toward becoming a multi-product company with direct commercial operations in the U.S. The company said it plans to use its experience in epilepsy drug development and commercialization to advance opakalim through its remaining clinical and regulatory stages.

Meanwhile, SK Biopharmaceuticals continues to expand the use of cenobamate. The company has submitted an application for an oral suspension formulation and is pursuing additional applications that could expand its use to primary generalized tonic-clonic seizures and pediatric patients.

The company is also expanding cenobamate internationally. Commercialization began in China in March through local partner Ignis Therapeutics, while launches in Peru, Chile and Brazil have taken place through Eurofarma. Regulatory work in Japan and preparations for a launch in South Korea are also underway.

If opakalim successfully completes clinical development and receives regulatory approval, SK Biopharmaceuticals could launch its second innovative medicine in the U.S. as early as 2029, strengthening its position in the global epilepsy market.