SK Biopharmaceuticals has entered into an agreement to in-license opakalim, an investigational antiseizure medication, from Biohaven and its wholly owned subsidiaries, marking a step in the South Korean drugmaker’s strategy to expand its global commercial portfolio.

The transaction is expected to help SK Biopharmaceuticals move beyond its current position as a single-commercial-product company. Subject to regulatory approval and successful development, the company plans to become a multi-product pharmaceutical company directly commercialising innovative medicines in global markets, with an initial focus on the United States.

Opakalim is a selective Kv7.2/7.3 potassium channel activator being developed as a potential treatment for epilepsy. The investigational therapy is currently being evaluated in Phase 2/3 clinical trials as an adjunctive treatment for adults with Partial-Onset Seizures (POS). More than 1,200 participants have been exposed to opakalim across clinical studies conducted to date.

The candidate is designed to selectively activate Kv7.2/7.3 channels, which play an important role in regulating neuronal excitability. Its selectivity is intended to distinguish opakalim from earlier-generation Kv7 activators and potentially reduce central nervous system side effects associated with some antiseizure medicines.

Clinical studies conducted to date have indicated a favourable safety and tolerability profile, according to the companies. SK Biopharmaceuticals expects initial topline results from the RISE 3 trial by the end of 2026. Subject to clinical and regulatory progress, the company is targeting a second data readout in 2028 and aims to launch opakalim in the United States as early as 2029.

Under the agreement, SK Biopharmaceuticals will pay up to USD 795 million in upfront and development and regulatory milestone payments related to the Kv7 platform. The consideration includes USD 400 million in upfront cash, comprising USD 350 million payable at closing and a further USD 50 million one year after closing. Up to an additional USD 395 million could be paid upon achievement of specified development and regulatory milestones.

A portion of future milestone and royalty payments will be payable to Knopp Biosciences, the original developer of the Kv7 technology. Completion of the transaction remains subject to required antitrust clearances and other customary closing conditions.

Following closing, SK Biopharmaceuticals will receive exclusive worldwide development and commercialisation rights to opakalim. The agreement will also provide access to Biohaven’s Kv7 discovery platform and related compounds generated through the platform, creating potential opportunities to expand SK Biopharmaceuticals’ pipeline beyond the current asset.

The deal builds on SK Biopharmaceuticals’ established expertise in epilepsy. Its marketed antiseizure medicine cenobamate, sold as Xcopri in the United States, has established a strong position in the US epilepsy market. The company plans to leverage its existing commercial infrastructure, including its dedicated US epilepsy organisation and neurology field force of more than 150 professionals, to support a potential future launch of opakalim.

SK Biopharmaceuticals said the combination of cenobamate and opakalim could enable it to address different treatment needs among people living with epilepsy. The company believes the two assets could form the foundation of a broader and differentiated epilepsy portfolio.

The company also plans to continue expanding cenobamate’s commercial potential through lifecycle management. The company has submitted a New Drug Application for an oral suspension formulation in the United States and is pursuing supplemental applications to expand the medicine’s label to include primary generalised tonic-clonic seizures and pediatric patients.

International expansion of cenobamate is progressing alongside these efforts. Commercialisation began in China in march through local partner Ignis Therapeutics, while launches have also taken place in Peru, Chile and Brazil through Eurofarma. Regulatory activities in Japan and launch preparations in South Korea are also underway.