Biohaven's Opakalim Shows Promise in Epilepsy Trials with Superior Tolerability Profile
Key Insights
Biohaven (search)'s selective Kv7.2/7.3 (search) channel activator opakalim (search) demonstrated a 3-fold prolongation in time to second generalized tonic-clonic seizure compared to placebo in idiopathic generalized epilepsy (search) patients.
In focal epilepsy (search) studies, 54% of patients achieved at least 50% reduction in seizure frequency over six months, with remarkably low rates of central nervous system adverse events.
The drug showed zero cases of somnolence, dizziness, fatigue, or memory impairment in the IGE study, contrasting sharply with double-digit adverse event rates reported for other investigational Kv7 activators.
Biohaven (search) Ltd. has reported compelling new clinical data for opakalim (search), its selective Kv7.2/7.3 (search) potassium channel activator, demonstrating significant seizure control across multiple epilepsy (search) populations while maintaining a markedly superior tolerability profile compared to existing and investigational antiseizure medicines.
Breakthrough Results in Idiopathic Generalized Epilepsy
In a randomized, placebo-controlled, time-to-event trial in idiopathic generalized epilepsy (search) (IGE), opakalim (search) 75 mg once-daily achieved a median time to the second day with a generalized tonic-clonic seizure of 141 days compared to 47 days in the placebo group, representing a 3-fold prolongation. The study enrolled 27 subjects with 15 receiving opakalim and 12 receiving placebo.
Notably, 33% of opakalim (search)-treated subjects completed the 24-week double-blind phase without a second generalized tonic-clonic seizure versus 0% of placebo subjects, while 20% of opakalim-treated subjects remained completely seizure-free compared to none in the placebo group.
Sustained Efficacy in Focal Epilepsy
Updated analysis from the ongoing open-label extension study in focal epilepsy (search) revealed that 54% of patients receiving opakalim (search) 75 mg once-daily achieved a ≥50% reduction in seizure frequency over any consecutive six months of treatment compared to pre-randomization baseline. The study demonstrated exceptional retention rates, with 95% of patients completing the double-blind phase and 95% rolling over to the optional open-label extension.
Remarkable Tolerability Advantage
What distinguishes opakalim (search) most significantly is its exceptional tolerability profile. In the IGE study, the opakalim group reported zero cases of somnolence, dizziness, fatigue, or memory impairment. In the focal epilepsy (search) open-label extension study, rates of these central nervous system adverse events were 5% or less for each category.
This profile contrasts dramatically with other investigational Kv7 activators. Published long-term data from a competitor's Kv7 activator showed dizziness in 25% of subjects, somnolence in 17%, memory impairment in 11%, and falls in 15% of subjects in open-label extension studies.
Compassionate Use Success in Rare Epilepsy
A six-month update on compassionate use treatment in a 9-year-old boy with KCNQ2-Developmental and Epileptic Encephalopathy (search) (KCNQ2-DEE) confirmed clinical stability and ongoing seizure control. The patient, who had a history of daily tonic seizures despite three concurrent antiseizure medicines, showed a 50% reduction in seizure counts on overnight EEG at six months relative to pre-opakalim (search) baseline.
Mechanism and Development Strategy
Dr. Jason Lerner, Medical Director of Research & Development and Epilepsy (search) Development Lead at Biohaven (search), emphasized the drug's differentiated mechanism: "What stands out is not just that opakalim (search) controls seizures — it's that it does so without the burdensome side effects that compromise quality of life and adherence for people with epilepsy."
Opakalim (search) is distinguished from other investigational Kv7 activators by its selectivity for Kv7.2/7.3 (search) channels and lack of GABA receptor (search) activity. This selectivity for the heteromeric channels that are the predominant regulators of neuronal excitability is hypothesized to underlie the drug's favorable tolerability profile.
Clinical Development Timeline
Biohaven (search) has studied opakalim (search) in more than 1,000 subjects across multiple clinical trials, consistently demonstrating a favorable tolerability profile. The company is currently conducting two Phase 2/3 randomized, double-blind, placebo-controlled studies comparing opakalim to placebo as adjunctive therapy for refractory focal onset epilepsy (search), with top-line results from the first pivotal study expected in the second half of 2026 to support registration.
The drug offers potential for once-daily, orally-administered treatment without the need for titration, addressing a significant unmet need for novel, effective, and well-tolerated antiseizure medicines in a patient population that frequently experiences compromised quality of life due to medication side effects.