FDA Slaps Partial Clinical Hold on Biohaven's Opakalim Days After $795M SK Biopharmaceuticals Licensing Deal
- On Aug 26, 2026, Biohaven granted SK Biopharmaceuticals global rights to its Kv7 ion-channel platform and lead candidate opakalim (BHV-7000/BHV-7043), a deal worth up to $795M — including $350M at closing (part of $400M in near-term cash), $150M in development/regulatory milestones, and tiered royalties on U.S. net sales.
- Opakalim is a selective Kv7.2/7.3 potassium-channel activator in Phase 2/3 development for focal epilepsy, with pivotal RISE-3 topline data expected in 2H 2026.
- On Sept 4, 2026, the FDA placed a partial clinical hold on the program after Biohaven flagged a metabolite observed in rodent studies whose relevance to humans is not yet established.
- The hold blocks new patient enrollment (mainly affecting RISE-2) but allows continued dosing of already-enrolled patients across the pivotal trials and open-label extension; RISE-3 is already fully enrolled.
- Biohaven says the RISE-3 readout timeline is not expected to change; the news still weighed heavily on Biohaven's stock.
Look at the cash waterfall before reading this as a disaster: SK already wired the firm money pre-hold, and Biohaven keeps it no matter what the FDA ultimately decides — the $395M in milestones and royalties was always the risk-bearing tranche, so SK's real downside exposure was deferred by deal structure, not dodged by luck. The sharper question is timing: a partial hold landing nine days after signature invites an obvious diligence question — was the rodent metabolite finding already in Biohaven's IND file when SK signed, or did SK simply outrun its own risk review? Practically, this is noise, not crisis: RISE-3 is fully enrolled, so the pivotal readout timeline is intact; only RISE-2's tail enrollment stalls. The bigger tail risk is reputational spillover to Kv7 as a mechanism class — that would sting Xenon's azetukalner more than it dents Biohaven's balance sheet.
Biohaven epilepsy drug suffers FDA hold days after attracting $350M deal ↗