Biohaven completes enrollment in focal epilepsy drug trial

Biohaven Ltd. (NYSE: BHVN) announced the completion of enrollment in RISE3, a pivotal Phase 2/3 randomized, double-blind, placebo-controlled study evaluating opakalim, a selective Kv7.2/7.3 channel activator, for the treatment of refractory focal epilepsy. Top-line results are expected in the second half of 2026.

RISE3 (NCT06309966) enrolled adult participants with refractory focal onset seizures who experienced at least four seizures per month while taking one to three concurrent antiseizure medicines (ASMs). After an eight-week observation phase, participants were randomized to opakalim 75 mg, 50 mg, or placebo once daily as adjunctive therapy for an eight-week double-blind treatment period. The primary endpoint measures the change from baseline in 28-day average seizure frequency.

A separate ongoing Phase 2/3 study, RISE2 (NCT06132893), uses identical entry criteria and endpoints but features a 12-week double-blind treatment period, evaluating opakalim 25 mg and 50 mg in Part A and 75 mg in Part B.

Data from an ongoing open-label extension study presented at Biohaven's May 2026 R&D Day showed that 54% of participants receiving opakalim 75 mg once daily achieved a 50% or greater reduction in seizure frequency over any consecutive six months compared to pre-randomization baseline, in a group of more than 100 participants. Reported nervous system adverse events included dizziness in 5% of participants and fatigue in 4%.

Approximately 95% of participants who completed the double-blind treatment period across RISE2 and RISE3 finished the study, and approximately 95% of those participants enrolled in the optional open-label extension.

"Completing enrollment in RISE3 marks an important milestone for the opakalim development program," said Jason Lerner, M.D., Medical Director and Epilepsy Development Lead at Biohaven. "We look forward to reporting top-line results in the second half of 2026."

Opakalim has been studied in more than 1,000 participants across multiple clinical trials, according to the company's statement.

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