A partial clinical hold on opakalim (BHV-7000), Biohaven Ltd.'s (NYSE: BHVN) selective Kv7.2/7.3 potassium channel activator in pivotal development for refractory focal epilepsy, arrives days after the New Haven-based company agreed to license the Kv7 platform to South Korea-based SK Biopharmaceuticals for up to USD 795 million, and with topline data from the pivotal BHV7000-303 study still expected in the second half of 2026. According to an 8-K filed with the SEC on September 9, 2026, the FDA issued a partial clinical hold letter on September 4, pausing new patient enrollment pending results of additional nonclinical studies characterizing a metabolite observed in rodent testing. Dosing continues for all patients already randomized across the program, more than 600 in total.
BHV7000-303, one of two pivotal studies in refractory focal epilepsy, was fully enrolled and randomized before the hold was issued; its topline data timeline is unaffected. BHV7000-302, the companion pivotal study with an 8-week double-blind treatment period, continues dosing but cannot enroll new patients. The open-label extension study (BHV7000-201) also continues dosing. Biohaven said it voluntarily applied equivalent enrollment restrictions to its global sites outside the US.
The metabolite in question was identified during routine nonclinical characterization. Biohaven said the significance of the findings in rodents to human safety is uncertain and may be species-specific. The company expects the additional nonclinical studies to generate clarifying data within weeks. All clinical and nonclinical data, including the metabolite findings, were disclosed to SK Biopharmaceuticals prior to signing the license agreement on August 26, 2026.
Opakalim activates Kv7.2/7.3 heteromeric potassium channels, reducing neuronal excitability through the M-current — a mechanism distinct from GABA receptor modulation, which the company attributes to the drug's reported low rates of somnolence and dizziness in clinical studies. More than 1,200 participants have been dosed across the development program to date.