FDA places partial clinical hold on Biohaven's epilepsy drug after rodent findings

Sep 10, 2026

The U.S. FDA has placed a partial clinical hold on Biohaven's experimental epilepsy drug BHV-7000 (opakalim) due to safety concerns over a metabolite identified in rodent studies. The hold pauses new patient enrollment in the late-stage RISE-2 trial, though existing patients continue treatment and the fully enrolled RISE-3 trial remains on track for late 2026 results. The setback follows Biohaven's recent $795 million licensing deal with SK Biopharmaceuticals, to whom Biohaven disclosed the rodent data prior to signing.

FDA partial clinical hold

▪On September 4, 2026, the U.S. Food and Drug Administration imposed a partial clinical hold on Biohaven's experimental epilepsy drug BHV-7000, also known as opakalim
▪Biohaven's shares fell by more than 10% on September 10, 2026, following the public disclosure of the U.S. Food and Drug Administration's partial clinical hold
▪More than 1,200 participants have received Biohaven's experimental drug BHV-7000, which Biohaven stated has been generally safe and well-tolerated to date

Rodent metabolite safety findings

▪Biohaven expects to obtain further animal data in the weeks following September 10, 2026, to assess whether the rodent metabolite finding is relevant to human safety
▪Biohaven stated that the significance of the rodent metabolite finding to humans is uncertain and may be specific to rodents
▪The U.S. Food and Drug Administration cited insufficient information to assess potential human risk from a drug-related metabolite identified during rodent testing of Biohaven's experimental drug BHV-7000

RISE-2 trial enrollment pause

▪Biohaven voluntarily extended the enrollment pause for the RISE-2 clinical trial of BHV-7000 to study sites located outside the United States
▪The U.S. Food and Drug Administration's partial clinical hold requires Biohaven to pause new patient enrollment in its ongoing late-stage RISE-2 clinical trial of BHV-7000
▪Patients already enrolled in the RISE-2 clinical trial and its related extension study will continue to receive treatment with BHV-7000 despite the enrollment pause

RISE-3 trial continues enrollment

▪The fully enrolled RISE-3 clinical trial of BHV-7000 remains on track to report results in the second half of 2026
▪The U.S. Food and Drug Administration's partial clinical hold does not affect Biohaven's separate late-stage RISE-3 trial of BHV-7000, which is already fully enrolled

SK Biopharmaceuticals licensing deal

▪The licensing deal between Biohaven and SK Biopharmaceuticals has not closed as of September 10, 2026, and remains subject to a U.S. antitrust filing
▪Biohaven disclosed all clinical and nonclinical data regarding the rodent metabolite to SK Biopharmaceuticals before signing the licensing deal on August 26, 2026
▪On August 26, 2026, Biohaven licensed the worldwide rights to BHV-7000 to South Korea's SK Biopharmaceuticals in a deal worth up to $795 million, including an immediate $350 million payout

Biohaven financial challenges

▪To address dwindling cash reserves, Biohaven has restructured, reduced research and development costs, and changed its scientific leadership
▪Biohaven has faced multiple clinical setbacks, including a regulatory rejection of a rare disease drug, a failed trial in spinal muscular atrophy, and a failed depression trial for BHV-7000