Biohaven seizure drug extends remission in broad clinical data update
Biohaven (NYSE:BHVN) released new clinical and safety data for opakalim, its selective Kv7.2/7.3 potassium channel activator, showing meaningful reductions in seizure frequency and a highly differentiated central nervous system safety profile across generalized and focal forms of epilepsy.
The New Haven, Connecticut-based biopharmaceutical firm announced Tuesday that in a randomized, placebo-controlled time-to-event trial evaluating patients with idiopathic generalized epilepsy (IGE), treatment with a 75 mg once-daily dose of opakalim prolonged the median time to a second generalized tonic-clonic seizure to 141 days.
By comparison, patients in the placebo cohort experienced a median time-to-event of 47 days, representing a threefold extension in seizure-free duration.
In a separate, ongoing open-label extension study assessing adults with refractory focal epilepsy, an updated interim analysis revealed that 54% of patients treated with the 75 mg once-daily dose achieved a 50% or greater reduction in seizure frequency over a consecutive six-month window compared to their pre-randomization baselines.
Biohaven also disclosed a six-month update on an ongoing compassionate-use program evaluating a pediatric patient with KCNQ2-Developmental and Epileptic Encephalopathy, a rare genetic disorder characterized by severe treatment-resistant seizures.
Overnight electroencephalogram tracking at the six-month interval confirmed ongoing clinical stability and a 50% drop in absolute seizure counts relative to the child's pre-treatment baseline.
Across an aggregate safety database now exceeding 1,000 human subjects, opakalim demonstrated a low incidence of central nervous system adverse events.
In the generalized epilepsy trial, the opakalim group reported zero instances of somnolence, dizziness, fatigue, or memory impairment.
In the focal epilepsy extension study, individual rates for those common neurological side effects remained at or below 5% each.
Management noted that this tolerability profile sharply differentiates opakalim from earlier, non-selective potassium channel modulators, which have historically been limited by double-digit rates of severe central nervous system toxicities caused by off-target GABA receptor interactions.
The positive data arrives as a key clinical catalyst for Biohaven ahead of its scheduled annual Research and Development Day.
The company confirmed it remains on track to receive top-line results in the second half of 2026 from the first of its two pivotal, global Phase 2/3 randomized, double-blind, placebo-controlled trials in refractory focal epilepsy to support its planned marketing authorization applications.
