EpilepsyGTx, Viralgen Partner on AAV Gene Therapy EPY201 Ahead of Planned First-in-Human Trial

EpilepsyGTx and Viralgen have entered a collaboration to support manufacturing of EPY201, an investigational adeno-associated virus (AAV)-based gene therapy being developed for patients with focal refractory epilepsy (FRE), according to a company announcement. The program is planned to enter first-in-human Phase 1/2a clinical testing in 2027.¹

Under the agreement, Viralgen, a contract development and manufacturing organization specializing in recombinant AAV gene therapies, will use its Aava manufacturing platform to support production of EPY201. The platform is designed for scalable AAV manufacturing and, according to Viralgen, has been used for more than 1,500 AAV batches. The collaboration represents the latest development milestone for EPY201 as EpilepsyGTx prepares to advance the program toward clinical testing.¹

"We are proud to partner with EpilepsyGTx on this important programme,” Jimmy Vanhove, chief executive officer of Viralgen, said in a statement.¹ “Our Aava platform is purpose-built to scale AAV programmes efficiently, and our manufacturing expertise positions us to help EpilepsyGTx advance EPY201 toward patients with focal refractory epilepsy as rapidly as possible."

Focal epilepsy is characterized by seizures that originate from a specific region of the brain. When seizures persist despite trials of at least 2 tolerated and appropriately selected antiseizure medications, the epilepsy is considered drug-resistant. EpilepsyGTx estimates that FRE affects approximately 10 million people worldwide, including approximately 2 million across the United States, United Kingdom, and European Union.¹

EPY201, also known as AAV9-CAMK2A-EKC, uses an AAV9 capsid to deliver an engineered form of the naturally occurring Kv1.1 potassium channel, referred to as EKC. The therapy also uses a CAMK2A promoter designed to favor expression in principal neurons. The approach is intended to increase potassium-channel activity and reduce neuronal and circuit excitability within the targeted epileptogenic region.²

The scientific rationale for the approach has been evaluated in several preclinical models. In a peer-reviewed study of focal cortical dysplasia, administration of AAV9-CAMK2A-EKC to the dysplastic region produced an approximately 64% reduction in seizure frequency in mice with spontaneous generalized seizures. The treatment did not improve or worsen performance on behavioral measures sensitive to frontal-lobe function and did not alter interictal discharges in animals without generalized seizures.³

Earlier work also evaluated engineered Kv1.1 delivered using an AAV2/9 vector in a rat model of temporal lobe epilepsy, where the approach reduced seizure frequency and duration. The findings provided preclinical support for using targeted potassium-channel expression to modulate neuronal excitability in focal epilepsy.²

EpilepsyGTx has reported additional development work for EPY201, including mouse efficacy and tolerability studies and GLP toxicology and biodistribution studies intended to support clinical development. In 2024, the company announced completion of large-animal biodistribution studies and reported that intraparenchymal administration of AAV9 produced highly localized distribution at the target region and was tolerated in the treated animals. These findings remain preclinical and have not established the safety or efficacy of EPY201 in humans.⁴

The planned clinical program will rely on targeted delivery of EPY201 directly into the seizure focus rather than systemic administration. In July 2026, EpilepsyGTx announced a partnership with ClearPoint Neuro to support delivery of EPY201 in the planned first-in-human Phase 1/2a study. The company said the trial will use the ClearPointSmartFlow Cannula and ClearPoint Neuro Navigation system for administration of the gene therapy to the targeted brain region.⁵

The targeted approach is intended to locally modulate neuronal excitability while limiting exposure outside the epileptogenic region. For patients with drug-resistant focal epilepsy, surgical treatment can include resection or ablation when the seizure focus can be adequately localized and safely treated. EPY201 is being developed as an alternative strategy that seeks to alter the excitability of the seizure focus without removing or ablating the targeted brain tissue. However, whether this approach can provide durable seizure control while maintaining an acceptable safety profile will need to be established in clinical studies.

EpilepsyGTx raised $33 million in a Series A financing in December 2025 to advance EPY201 through first-in-human Phase 1/2a testing.The company subsequently added clinical-development and delivery partnerships as it prepared the program for clinical testing.¹

EPY201 remains an investigational, preclinical-stage therapy, and no human safety or efficacy data have been reported. The planned Phase 1/2a study is expected to provide the first clinical assessment of the approach in patients with focal refractory epilepsy.

REFERENCES
1. EpilepsyGTx, Viralgen. EpilepsyGTx and Viralgen collaborate to advance AAV gene therapy programme for epilepsy ahead of first-in-human trial. News release. September 9, 2026. Accessed September 28, 2026. https://www.prnewswire.com/news-releases/epilepsygtx-and-viralgen-collaborate-to-advance-aav-gene-therapy-programme-for-epilepsy-ahead-of-first-in-human-trial-302872656.html
2. Snowball A, Chabrol E, Wykes RC, et al. Epilepsy gene therapy using an engineered potassium channel. J Neurosci. 2019;39(16):3159-3169. doi:10.1523/JNEUROSCI.1143-18.2019
3. AlmacellasBarbanoj A, Graham RT, Maffei B, et al. Anti-seizure gene therapy for focal cortical dysplasia. Brain. 2024;147(2):542-553. doi:10.1093/brain/awad387.
4. Focalis Bio announces completion of the large animal biodistribution studies supporting lead program EPY201. FocalisBio. News release. June 10, 2024. Accessed September 28, 2026. https://focalisbio.com/news/focalis-bio-announces-completion-of-the-large-animal-biodistribution-studies-supporting-lead-program-epy201
5. Focalis Bio partners with ClearPoint Neuro to support targeted delivery of lead gene therapy in epilepsy.Focalis Bio. News release. July 14, 2026. Accessed September 28, 2026.