Drug developer Biohaven has completed enrollment in its pivotal Phase II/III RISE3 trial evaluating opakalim, a selective Kv7.2/7.3 channel activator, for treating refractory focal epilepsy, according to company filings. The trial, designed to assess the safety and efficacy of the experimental medication, marks a critical step in the development of novel therapies for patients with treatment-resistant seizures.
The RISE3 trial, which enrolled participants across multiple global sites, aims to determine whether opakalim can reduce seizure frequency in individuals who have not responded to conventional anti-epileptic drugs. Biohaven, based in New Haven, Connecticut, has positioned the study as a key milestone in its epilepsy research program, with results anticipated to inform regulatory submissions later this year.
Understanding Refractory Focal Epilepsy
Refractory focal epilepsy, also known as drug-resistant focal epilepsy, affects approximately 30% of people with epilepsy, according to the World Health Organization. These patients experience seizures that persist despite treatment with two or more appropriate anti-epileptic medications. The condition can significantly impair quality of life, increasing risks of injury, cognitive decline, and psychiatric comorbidities.
Opakalim targets the Kv7.2/7.3 potassium channels, which regulate neuronal excitability. By enhancing the activity of these channels, the drug aims to stabilize nerve cell membranes and prevent seizure propagation. This mechanism differs from traditional anti-epileptic drugs, which often act on sodium or GABA receptors.
RISE3 Trial Design and Objectives
The RISE3 trial is a randomized, double-blind, placebo-controlled study that enrolled 288 participants aged 12 and older with refractory focal epilepsy. Participants were assigned to receive either opakalim or a placebo, with primary endpoints including the change in weekly seizure frequency from baseline to the final treatment period.
Secondary endpoints included measures of seizure freedom, quality of life, and safety. The trial’s open-label extension phase, which began in 2023, is designed to evaluate the long-term safety and effectiveness of opakalim over 12 months.
Regulatory and Clinical Implications
Results from the RISE3 trial are expected to be submitted to the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) as part of a Biologics License Application (BLA) and Marketing Authorization Application (MAA), respectively. If approved, opakalim would become the first Kv7.2/7.3 channel activator to reach the market for epilepsy.
The trial’s outcomes could also influence guidelines for the management of refractory epilepsy. The American Epilepsy Society and the International League Against Epilepsy are currently reviewing updated treatment protocols, which may incorporate new pharmacological options like opakalim.
Challenges and Next Steps
Despite the trial’s completion, several challenges remain. The safety profile of opakalim must be thoroughly evaluated, as potassium channel modulators can have off-target effects. Additionally, the drug’s efficacy in diverse patient populations, including those with comorbid conditions, requires further investigation.
Biohaven has indicated that it will continue to monitor trial participants through the open-label extension phase. The company also plans to initiate additional studies to explore opakalim’s potential in other seizure disorders, such as Dravet syndrome and Lennox-G