Opakalim's $795M Kv7 Bet: Mechanism Redeemed or Liability Transferred?

Biohaven and SK Biopharmaceuticals Ink Global Licensing Deal for Opakalim

Biohaven and SK Biopharmaceuticals have announced a strategic global licensing and collaboration agreement. Under the terms, SK Biopharmaceuticals will obtain an exclusive worldwide license to Biohaven's Kv7 ion channel platform, including opakalim (BHV-7000), a selective Kv7.2/7.3 potassium channel activator in Phase 2/3 development for focal epilepsy. Biohaven stands to receive up to $795 million in upfront and milestone payments, including $400 million in near-term cash, plus tiered royalties on U.S. net sales and additional global milestones. SK Biopharmaceuticals will also assume future Kv7 program costs and certain obligations. This partnership aims to leverage SK Biopharmaceuticals' commercial expertise to accelerate opakalim's path to market.

• Financial Structure and Value: The agreement provides Biohaven with significant non-dilutive capital, including $400 million in near-term cash ($350 million at closing, $50 million in 2027), and eligibility for an additional $150 million in development and regulatory milestones. Total potential payments related to the Kv7 platform could reach $795 million, alongside tiered royalties on U.S. net sales of opakalim ranging from mid-teens to low twenties, and mid-single digit royalties ex-U.S.
• Strategic Rationale and Market Access: This partnership strategically combines Biohaven's innovative Kv7 platform with SK Biopharmaceuticals' established global development, regulatory, and commercial capabilities in epilepsy, notably their success with XCOPRI. This collaboration is designed to provide opakalim with an accelerated and robust pathway to patients worldwide, leveraging SK Biopharmaceuticals' existing infrastructure without Biohaven needing to build its own capital-intensive commercial organization.
• Opakalim's Profile and Development Status: Opakalim (BHV-7000) is a next-generation, selective Kv7.2/7.3 potassium channel activator, currently in Phase 2/3 development for focal epilepsy. It is designed to offer a once-daily oral treatment with a favorable tolerability profile, aiming for meaningful efficacy without the burdensome CNS side effects common with other antiseizure medicines. Topline results from the RISE3 trial are anticipated in the second half of 2026.

Addressing Persistent Unmet Needs in Focal Epilepsy Management

Despite meaningful advances in antiseizure therapeutics and neuromodulation, substantial gaps remain in the management of focal epilepsy — particularly for patients with drug-resistant disease, rare genetic etiologies, and underrepresented demographics. Recent literature highlights several distinct populations where current standard-of-care falls critically short, driving targeted research and clinical innovation across pharmacological, surgical, and device-based modalities.

• Highly pharmacoresistant and refractory focal epilepsy: Patients who have failed multiple antiseizure regimens — including those with Rasmussen's encephalitis-related focal epilepsy resistant to more than 10 prior treatments — represent one of the most pressing unmet needs. Add-on cenobamate has demonstrated superiority over all prior antiseizure and immunomodulatory therapies in such cases, achieving complete control of focal to bilateral tonic-clonic seizures (FBTCS) and elimination of focal motor status epilepticus. Super-refractory status epilepticus (SRSE), defined by seizure persistence beyond seven days despite anesthetic therapy, represents an adjacent life-threatening population requiring multimodal approaches including surgical resection, VNS, and botulinum toxin therapy.

• Genetic and structural epilepsy subpopulations: Patients harboring pathogenic variants in the PI3K-AKT-mTOR pathway and GATOR1 complex genes (mTORopathies) frequently require resective neurosurgery due to inadequate response to antiseizure medications and mTOR inhibitors. DEPDC5-related epilepsy — assessed across 586 variant carriers from 170 families — shows drug resistance in 48.3% of cases, with early seizure onset strongly correlating with drug resistance (p = 2.4e-08), intellectual disability (p = 2.1e-08), and lesional MRI findings (p = 2.2e-08). Among drug-resistant individuals who underwent surgery (34.7%), 88% achieved favorable outcomes (Engel I or II), underscoring the critical need for early genetic testing and surgical candidacy evaluation. Hemimegalencephaly (HME) driven by mosaic variants in PIK3CA, MTOR, and AKT3 similarly necessitates multidisciplinary, genotype-informed management strategies.

• Focal to bilateral tonic-clonic seizures and SUDEP risk: FBTCS carry the highest risk of sudden unexpected death in epilepsy (SUDEP), a leading cause of premature mortality in this population. Cenobamate's demonstrated efficacy in controlling FBTCS in drug-resistant focal epilepsy was associated with a reduction in all-cause mortality to rates statistically indistinguishable from that of the general population — a clinically significant finding for a condition where mortality reduction has historically been an elusive goal.

• Neuromodulation-eligible patients with suboptimal device response: Drug-resistant focal epilepsy patients who fail to achieve adequate seizure control with a first neuromodulation device should not be categorised as neuromodulation failures. A reported case of a 28-year-old male demonstrated a 75% seizure reduction following centromedian-parafascicular (CM-Pf) deep brain stimulation (DBS) as a third device, after suboptimal responses to both VNS and responsive neurostimulation (RNS), with subsequent seizure freedom from FBTCS at nine months. Trigeminal nerve stimulation (TNS) has also emerged as a viable adjunctive option, with a systematic review of 148 patients demonstrating significant seizure frequency reductions and a favourable safety profile — no serious or life-threatening adverse events were reported.

• Underrepresented demographic populations: Adult Asian patients with focal-onset seizures have been systematically underrepresented in antiseizure medication trials. A dedicated phase III study (EP0083; NCT03083665) evaluated adjunctive brivaracetam in 448 adult Asian patients (mean age 34.5 years; 53.8% female) with inadequate seizure control on one or two concomitant antiseizure medications, directly addressing the evidence gap created by the predominance of non-Asian study populations in prior brivaracetam trials.

• Pediatric early-onset genetic epilepsy: Children with early-onset DEPDC5-related epilepsy represent a high-priority surgical and therapeutic target, with cumulative epilepsy penetrance reaching 64.9% by age 10 and 76.1% by age 10 among variant carriers. The strong association between early seizure onset and adverse outcomes — including drug resistance and intellectual disability — highlights the need for accelerated genetic diagnostic pathways and early surgical intervention in this paediatric cohort.

SK Biopharma's Proven Epilepsy Expertise to Accelerate Opakalim's Reach

Over the past five years, the focal epilepsy treatment landscape has been meaningfully reshaped by the emergence of novel anti-seizure medications (ASMs) demonstrating robust efficacy in drug-resistant populations. Cenobamate has generated particularly compelling real-world evidence, with Early Access Program data from Germany, France, and the United Kingdom reporting a 50% responder rate of 49.3% at three months of maintenance and complete seizure freedom in 13.6% of patients, alongside 12-month retention rates of 69.7%. A separate multicentre cohort corroborated these findings, with retention of 77.8% at 12 months and sustained 50% seizure reduction in 47.7% of patients. Perampanel has similarly demonstrated durable effectiveness — the PERPRISE study reported 12-month retention of 66.7% as adjunctive monotherapy, with seizure-freedom rates of 42.3% for focal to bilateral tonic-clonic seizures. In pediatric cohorts, perampanel monotherapy achieved a 77.8% seizure-freedom rate during weeks 13–26 in newly diagnosed patients aged 4–12. Brivaracetam as conversion monotherapy further expanded the toolkit, with real-world retention of 83.9% at 12 months and seizure freedom in 58.1% of patients at the same timepoint.

Alongside pharmacological advances, the surgical and neuromodulatory landscape has undergone a notable structural shift. Analysis of the U.S. National Inpatient Sample from 2010 to 2020 revealed a measurable migration away from traditional surgical resection and vagus nerve stimulation toward laser interstitial thermal therapy (LITT) and responsive neurostimulation (RNS). Among the surgical cases reviewed, resection accounted for 78% of procedures, while RNS and LITT represented 8% and 6%, respectively — with both modalities increasing over the decade. Magnetic resonance-guided LITT has gained traction as a minimally invasive alternative, though standardized protocols and large prospective efficacy data remain outstanding needs. In parallel, deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS) has been established as a clinically validated option for drug-resistant focal epilepsy, with mechanistic research identifying strengthened pre-ictal ANT-to-epileptogenic zone connectivity as a key determinant of therapeutic response — a finding with direct implications for surgical candidate selection and personalized stimulation strategies.

A third defining trend of the past five years has been the formal integration of patient-centered outcomes into epilepsy care frameworks. An Italian Delphi consensus study achieved agreement on 23 of 26 clinical statements, with strong alignment on the necessity of timely intervention, individualized treatment planning, and the role of patient-reported outcomes (PROs) in routine clinical practice. Electronic PRO tools are increasingly being deployed to capture real-time seizure data, with 86.3% of study participants endorsing brief symptom training prior to diary completion and 66.6% supporting seizure reporting within a 10-minute window. Persistent gaps remain, however — particularly the scarcity of pediatric-specific trial data, inadequate attention to pediatric-to-adult care transitions, and divergent clinical views on the routine incorporation of epilepsy surgery and EEG monitoring in uncontrolled focal epilepsy management.

Opakalim: A Strategic Bet to Revitalize Kv7 in Focal Epilepsy

The recent licensing agreement between Biohaven and SK Biopharmaceuticals for the Kv7 ion channel platform, featuring opakalim (BHV-7000), represents a calculated strategic move with significant implications for the epilepsy treatment landscape. This partnership aims to accelerate the development and commercialization of a novel Kv7.2/7.3 potassium channel activator for focal epilepsy, a condition characterized by a persistent unmet need for effective and well-tolerated therapies.

The Kv7 channel mechanism has long been recognized for its potential in epilepsy, given its critical role in neuronal excitability. However, the withdrawal of the first-generation Kv7 activator, retigabine, due to safety concerns such as pigmentation changes, left a void and a cautious sentiment around this drug class. Opakalim's journey through Phase 1, demonstrating excellent tolerability at therapeutically relevant concentrations, suggests a potential to overcome these historical challenges. Its selectivity for heteromeric Kv7.2/7.3 channels, as highlighted in research, could be key to a differentiated safety and efficacy profile.

For SK Biopharmaceuticals, this deal is a bold bet, providing a late-stage asset that could significantly expand its neurological portfolio. Their commercial expertise will be crucial in navigating the complex epilepsy market, where existing adjunctive therapies like lacosamide, while effective for many, still see considerable discontinuation rates due to adverse events or lack of efficacy. Similarly, other novel approaches, such as transdermal cannabidiol, have not shown significant efficacy in adult focal epilepsy in double-blind trials, underscoring the persistent need for new options.

However, the path forward is not without risks. The primary challenge remains demonstrating robust clinical efficacy in Phase 2/3 trials, as preclinical and early-stage tolerability do not guarantee success in broader patient populations. Furthermore, despite its selective profile, the potential for unexpected safety signals in larger, longer-term studies cannot be entirely discounted. The competitive environment is also intensifying, with other Kv7 activators and diverse mechanisms of action advancing through clinical development. Should opakalim successfully navigate these hurdles, it could not only provide a valuable new treatment option for patients but also revitalize interest and investment in the Kv7 channel class, potentially ushering in a new era for targeted epilepsy therapeutics.