Biohaven and SK Pharmaceuticals have struck a licensing and partnership deal which will see the pair join forces to progress an epilepsy therapy that – if approved – could become one of the first potassium channel openers to reach the epilepsy market.
In exchange for up to $795m in upfront and milestone payments, as well as potential tiered royalties on US sales ranging from the mid-teens to low twenties, Biohaven will hand over the global rights to its Kv7 ion channel platform. This includes the company’s lead epilepsy asset and deal centrepiece, opakalim.
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Kv7 is a family of voltage-gated potassium channels that control electrical activity and cell excitability in the nervous system, heart and muscles.
As per the agreement, SK will also take on all costs associated with the progression of the Kv7 platform, while pledging up to $245m towards third party and future platform expenses.
Through this agreement, Biohaven and SK will progress opakalim – a selective Kv7.2/7.3 potassium channel activator – through late-stage development and on to potential approval in focal epilepsy. Currently, Biohaven is exploring opakalim’s potential in the indication through the Phase II/III RISE3 study, which is expected to read out in the second half of this year.
SK enters potassium channel opener race
This deal will see SK, the company behind approved anti-focal-onset seizure pill, Xcopri (cenobamate), join the race to market with Xenon’s fellow Kv7.2/7.3 opener, azetukalner, which analysts are touting as a promising therapy in the indication after a Phase III score. Azetukalner may hold the first-to-market advantage, however, as the biotech plans to submit a New Drug Application (NDA) to US regulators for the therapy in Q3 2026, while Biohaven is still awaiting results from RISE3. There are currently no approved potassium channel openers on the epilepsy market.
Thus far, opakalim has demonstrated a cleaner central nervous system (CNS)-based side effect profile than azetukalner, with the former drug resulting in less dizziness, sedation and fatigue than its rival. However, Leerink analysts highlight the potential controversy around opakalim’s adverse event (AE) profile, which they say could be the result of weaker target engagement rather than better selectivity – meaning investors are questioning if it will match azetukalner’s efficacy.
If either drug secures approval in focal epilepsy, they will enter a wider market that GlobalData estimates will be worth $17.8bn in 2035 across the seven major markets (7MM: the US, France, Germany, Italy, Spain, the UK and Japan). Currently, GlobalData, parent company of Pharmaceutical Technology, names opakalim as one of the 12 late-stage pipeline products that could represent key catalysts for the future growth of the epilepsy market.
