New Clinical Data Reinforce Opakalim’s Potential as a Selective Antiseizure Therapy Option

Biohaven has reported new clinical data on opakalim (BHV-7000), its investigational selective Kv7.2/7.3 potassium channel activator, showing encouraging efficacy and tolerability signals across multiple epilepsy populations, including idiopathic generalized epilepsy (IGE), focal epilepsy, and KCNQ2 developmental and epileptic encephalopathy (KCNQ2-DEE).¹

The findings were unveiled ahead of the company's annual R&D Day and come as Biohaven prepares for top-line results from the first of two pivotal phase 2/3 focal epilepsy studies expected in the second half of 2026. In addition, the newly released data add to a growing body of evidence supporting opakalim as a potential next-generation antiseizure medication designed to selectively target Kv7.2/7.3 channels without the GABA-related activity that may contribute to central nervous system (CNS) adverse events seen with many currently available therapies.¹

In a randomized, double-blind, placebo-controlled proof-of-concept study (NCT06425159), investigators evaluated once-daily opakalim 75 mg in patients with IGE and treatment-resistant generalized tonic-clonic (GTC) seizures. Although the study was closed before reaching its planned enrollment target because of recruitment challenges and portfolio prioritization decisions, the dataset demonstrated signals of efficacy and tolerability.

Among the 27 enrolled participants, median time to a second GTC seizure during the 24-week treatment period was 141 days for patients receiving opakalim compared with 47 days for those receiving placebo, representing a roughly threefold prolongation in time to seizure recurrence. Additionally, 33% of opakalim-treated participants completed the double-blind phase without experiencing a second GTC seizure, while no placebo-treated participants achieved that outcome. Notably, 20% of patients receiving opakalim remained seizure-free throughout the treatment period compared with 0% in the placebo arm.¹

“The opakalim data across IGE, focal epilepsy and KCNQ2-DEE are consistent and compelling,” Jason Lerner, MD, medical director, Research & Development and Epilepsy Development Lead, Biohaven, said in a statement.¹ “What stands out is not just that opakalim controls seizures — it's that it does so without the burdensome side effects that compromise quality of life and adherence for people with epilepsy. Dizziness, somnolence, fatigue, and memory impairment are reported in meaningful proportions of patients on existing and investigational ASMs.”

Biohaven also highlighted the therapy's favorable tolerability profile in the study. According to the company, no cases of somnolence, dizziness, fatigue, or memory impairment were observed among opakalim-treated participants in the small proof-of-concept trial.

Lerner added, “Opakalim's zero rates of somnolence, dizziness, fatigue, and memory impairment in our small IGE proof-of-concept study, and single-digit rates of CNS adverse events in our focal epilepsy program suggest that selective Kv7.2/7.3 activation is a fundamentally different and cleaner mechanism. I believe opakalim can offer people with epilepsy real seizure control without asking them to compromise their quality of life."

Additional updates were presented from the ongoing open-label extension (OLE) study in focal epilepsy (NCT06443463). As of the first half of 2026, both completion rates in the double-blind study and rollover rates into the extension study were reported at 95%, suggesting continued patient and investigator participation.

Among more than 100 participants who completed six months of treatment with opakalim 75 mg once daily, 54% achieved at least a 50% reduction in seizure frequency compared with pretreatment baseline. Biohaven noted that this responder rate is comparable to results reported with the investigational Kv7 activator azetukalner (Xenon Pharmaceuticals); however, the company emphasized that opakalim demonstrated lower reported rates of CNS adverse events.¹

The updated safety analysis showed dizziness in 5.0% of opakalim-treated participants, while previously reported long-term data for another investigational Kv7 activator showed rates of dizziness, somnolence, memory impairment, and falls of 25%, 17%, 11%, and 15%, respectively. The company believes the differentiated safety profile may stem from opakalim's selective activation of Kv7.2/7.3 channels and lack of meaningful GABA receptor activity.¹

READ MORE: Anup Patel, MD, on Expanding Role of AI and Collaboration in Pediatric Epilepsy Research

Biohaven also provided a six-month clinical update on a 9-year-old boy with KCNQ2-DEE who is receiving opakalim under a single-patient investigational new drug authorization. The patient had experienced refractory epilepsy despite treatment with 3 concomitant antiseizure medications, including a first-generation Kv7 activator, and had previously developed status epilepticus and developmental regression when attempts were made to taper therapy.

According to the update, the patient remained clinically stable after six months of treatment. Overnight electroencephalography demonstrated a 50% reduction in seizure counts relative to baseline, and treatment continued to be well tolerated.

Opakalim is currently being studied in two pivotal phase 2/3 randomized, placebo-controlled trials in refractory focal epilepsy (NCT06132893 and NCT06309966). The agent has been evaluated in more than 1,000 participants across clinical studies and was previously shown to engage CNS targets in a phase 1 electroencephalography biomarker study that demonstrated dose-dependent increases in brain spectral power.²

The therapy's development program has focused primarily on epilepsy after Biohaven elected not to pursue further psychiatric development following a phase 2 proof-of-concept study in major depressive disorder that failed to meet its primary endpoint despite a generally favorable safety profile.³

With pivotal focal epilepsy data anticipated later this year, the latest findings provide additional support for opakalim's potential as a novel antiseizure therapy designed to balance seizure control with improved tolerability, an area of persistent unmet need for many patients living with epilepsy.¹

REFERENCES
1. Biohaven Ltd. Biohaven reports new data from selective Kv7.2/7.3 activator program and provides epilepsy pipeline update at 2026 R&D Day. News release. Biohaven. Accessed May 26, 2026. https://www.prnewswire.com/news-releases/biohaven-reports-new-clinical-data-in-epilepsy-with-opakalim-a-selective-kv7-27-3-activator-highlighting-seizure-control-and-markedly-differentiated-tolerability-profile-302781743.html
2. Biohaven announces positive data from its exploratory electroencephalogram (EEG) biomarker study of BHV-7000, completion of once-daily formulation development, and plan to initiate phase 3 pivotal studies. News release. September 5, 2023. https://www.prnewswire.com/news-releases/biohaven-announces-positive-data-from-its-exploratory-electroencephalogram-eeg-biomarker-study-of-bhv-7000-completion-of-once-daily-formulation-development-and-plan-to-initiate-phase-3-pivotal-studies-301917174.html
3. Biohaven reports results from phase 2 proof-of-concept study evaluating BHV-7000 for the treatment of major depressive disorder. News release. December 24, 2025. https://www.prnewswire.com/news-releases/biohaven-reports-results-from-phase-2-proof-of-concept-study-evaluating-bhv-7000-for-the-treatment-of-major-depressive-disorder-302389634.html