US FDA pauses new enrollment in Biohaven epilepsy drug trials

• The FDA cited insufficient information to assess human risk from a metabolite found in rodent testing, though Biohaven says the finding's significance to humans is uncertain and may be rodent-specific
• More than 1,200 participants have received BHV-7000 with generally good safety results; one late-stage trial remains on track to report results in the second half of 2026
• Biohaven disclosed the findings to SK Biopharmaceuticals before their August 26 deal granting worldwide rights to BHV-7000, with the transaction still pending U.S. antitrust approval

Summary: US FDA Pauses New Enrollment in Biohaven Epilepsy Drug Trials

Key Development:

The U.S. Food and Drug Administration imposed a partial clinical hold on Biohaven's experimental epilepsy drug BHV-7000 on September 4, halting new patient enrollment following concerning metabolite findings in rodent testing. The FDA cited insufficient information to assess potential human risks from the metabolite produced when the drug is broken down in the body.

Company Response:

Biohaven voluntarily extended the enrollment pause to sites outside the U.S., though the company noted the finding's significance to humans remains uncertain and may be rodent-specific. Over 600 patients already enrolled can continue receiving treatment, and more than 1,200 participants have received BHV-7000 to date with generally safe and well-tolerated results.

Trial Impact:

One fully enrolled late-stage trial remains on track to report results in the second half of 2026. A second trial has paused enrollment, though existing patients and those in extension studies will continue treatment. The company expects additional animal data in the coming weeks to clarify human safety relevance.

Deal Implications:

Biohaven disclosed these findings to SK Biopharmaceuticals before their August 26 deal granting SK worldwide rights to BHV-7000 and related drugs. The transaction has not closed and remains subject to U.S. antitrust filing approval.

Drug Profile:

BHV-7000 is being developed to treat refractory focal epilepsy—seizures originating in one brain area that persist despite treatment with at least two anti-seizure medications.

Market Impact:

The announcement sent Biohaven's shares lower, raising concerns about the drug's regulatory pathway and the pending SK Biopharmaceuticals deal.