Biohaven's Opakalim Extends Seizure Interval Threefold, Achieves 54% Responder Rate
BHVN•Biohaven's 75 mg opakalim extended median time to second generalized tonic-clonic seizure to 141 days versus 47 days for placebo and drove a 54% ≥50% seizure reduction rate in focal epilepsy OLE. The Kv7.2/7.3 activator showed ≤5% CNS adverse events and no somnolence, dizziness, fatigue or memory impairment.
1. Proof-of-Concept IGE Trial
In a randomized, placebo-controlled proof-of-concept study in idiopathic generalized epilepsy, subjects receiving opakalim 75 mg once daily experienced a median time to second generalized tonic-clonic seizure of 141 days versus 47 days for placebo, representing a three-fold prolongation. One-third of treated patients completed 24 weeks without a second seizure and 20% remained seizure-free, while reporting zero rates of somnolence, dizziness, fatigue or memory impairment.
2. Focal Epilepsy Open-Label Extension
An ongoing open-label extension in refractory focal epilepsy saw 54% of over 100 six-month completers achieve at least a 50% reduction in seizure frequency compared with pre-randomization baseline. Study completion and rollover rates both reached 95%, underscoring patient and investigator confidence in opakalim’s efficacy and tolerability profile.
3. Safety Profile and Next Milestones
Opakalim has been administered to over 1,000 subjects across IGE, focal epilepsy and KCNQ2-DEE compassionate use, with ≤5% incidence of key CNS adverse events and markedly lower tolerability issues than other Kv7 activators. Top-line results from the first pivotal Phase 2/3 refractory focal epilepsy study are on track for the second half of 2026, with additional data to be presented at the upcoming R&D Day.
