Biohaven’s Opakalim Nears Regulatory Filing as Biohaven Reports New Epilepsy Data

Biohaven Ltd. presented new clinical data for opakalim (BHV-7000), its selective Kv7.2/7.3 potassium channel activator, across idiopathic generalized epilepsy (IGE), refractory focal epilepsy, and KCNQ2 developmental and epileptic encephalopathy (KCNQ2-DEE) during its annual R&D Day held alongside the Yale Innovation Summit.

The data strengthen Biohaven’s position in the competitive epilepsy market by highlighting opakalim’s differentiated safety profile alongside clinically meaningful seizure control. Unlike earlier Kv7 activators and many approved antiseizure medicines (ASMs), opakalim selectively targets Kv7.2/7.3 channels without significant GABA receptor activity, a feature that may reduce central nervous system adverse events such as dizziness, somnolence, fatigue, and cognitive impairment.

Proof-of-Concept in Idiopathic Generalized Epilepsy

Biohaven reported findings from a randomized, double-blind, placebo-controlled proof-of-concept study (NCT06425159) evaluating once-daily opakalim 75 mg in patients with treatment-resistant IGE and generalized tonic-clonic (GTC) seizures. The study enrolled 27 patients, including 15 receiving opakalim and 12 receiving placebo, before early closure due to recruitment challenges and portfolio prioritization.

Despite the limited enrollment, opakalim demonstrated a notable efficacy signal. Median time to second GTC seizure reached 141 days compared with 47 days for placebo, representing a threefold prolongation. One-third of opakalim-treated patients completed the 24-week double-blind period without seizure recurrence, while 20% remained seizure-free throughout the study. No placebo-treated patients achieved either outcome.

Importantly, investigators reported no cases of somnolence, dizziness, fatigue, or memory impairment in the IGE cohort.

Durable Response in Focal Epilepsy

Updated data from the ongoing open-label extension study in refractory focal epilepsy (NCT06443463) further supported opakalim’s long-term activity and tolerability. Among patients completing six months of treatment, more than half achieved at least a 50% reduction in seizure frequency compared with baseline before randomization.

Biohaven reported efficacy comparable to investigational Kv7 activator azetukalner, with markedly lower CNS adverse events. Dizziness occurred in only 5% of opakalim-treated patients, substantially below rates previously reported with competing Kv7 activators in long-term studies.

The findings suggest selective Kv7.2/7.3 activation may provide durable seizure control with improved tolerability relative to both investigational Kv7 therapies and established ASMs.

Pediatric KCNQ2-DEE Case Update

Biohaven also provided a six-month update for a 9-year-old boy with refractory KCNQ2-DEE receiving compassionate-use opakalim under a single-patient IND authorized by the U.S. Food and Drug Administration.

The patient previously experienced daily tonic seizures despite treatment with three ASMs, including a first-generation Kv7 activator. Following transition to opakalim, overnight EEG assessments showed a 50% reduction in seizure counts relative to baseline. Clinical stability and favorable tolerability were maintained throughout six months of treatment.

Path to Regulatory Submission

Jason Lerner, Medical Director and Epilepsy Development Lead at Biohaven, said the emerging data support selective Kv7.2/7.3 activation as a potentially differentiated approach for seizure control without the CNS tolerability burden commonly associated with current ASMs.

Biohaven expects topline results from the first of two pivotal Phase 2/3 focal epilepsy studies in the second half of 2026 as the company advances opakalim toward potential regulatory submission.

The emerging dataset supports broader development of opakalim across focal, generalized, and developmental epilepsies, particularly in patients who remain uncontrolled on currently available ASMs.

Reference

Biohaven Reports New Clinical Data in Epilepsy with Opakalim, a Selective Kv7.2/7.3 Activator, Highlighting Seizure Control and Markedly Differentiated Tolerability Profile | Biohaven, Ltd.