Gene Therapy Upstart EpilepsyGTx Secures $33 Million Series A to Advance AAV-Based Epilepsy Program

December 7, 2025 —Endpoints News — A London-based biotech focused on gene therapies for epilepsy, EpilepsyGTx, has successfully closed a $33 million Series A funding round. The funding will propel the company’s lead candidate, EPY201, an AAV-based gene therapy, toward a Phase 1/2a clinical trial in the UK and Europe for patients with focal refractory epilepsy (FRE).

The gene therapy space, while recently battling funding constraints, still sees strategic investment in promising platforms. EpilepsyGTx was able to convince investors of the potential of its pipeline of three candidates for FRE. The raise was supported by XGEN Venture, the British Business Bank, and an undisclosed global biopharma.

EPY201: An AAV9 Approach to Taming Seizures

The lead program, EPY201 (AAV9-CAMK2A-EKC), leverages the power of adeno-associated virus (AAV) vectors, specifically the AAV9 capsid, which acts as a “shuttle” to deliver a therapeutic transgene directly into the brain.

• The Vector: EPY201 utilizes the AAV9 capsid for its delivery system.

• The Payload: The AAV9 vector carries a transgene that codes for an engineered Kv1.1 potassium channel (EKC).

• Targeting: The construct also employs a CAMK2A promoter to bias the expression of the transgene to excitatory neurons within the seizure focus, enhancing the therapeutic effect where it is needed most.

Following localized administration, the AAV9-based gene therapy enables neurons to increase the production of the Kv1.1 potassium channel protein. This protein makes neurons less excitable and reduces neurotransmitter release, profoundly decreasing the tendency of local neural circuits to generate seizures.

Clinical Plans and Focused Delivery

EpilepsyGTx plans to initiate its Phase 1/2a study around the end of next year, enrolling approximately 30 adults with FRE—patients who continue to experience seizures despite trying at least two anti-seizure medications. The primary goal is to assess whether the AAV gene therapy can significantly reduce seizures and potentially achieve seizure freedom one year post-treatment.

CEO Nicolas Koebel noted the AAV9-based gene therapy is delivered via a catheter directly into the seizure focal point, which represents less than 1% of the total brain volume.

“The injection hole is about the diameter of a grain of rice,” Koebel said, emphasizing the highly localized nature of the treatment.

Biodistribution studies have shown 99% of the AAV gene therapy remains within less than one centimeter from the infusion site, confirming its precise targeting. The programs are based on UCL findings, where researchers found anti-epileptic properties in the KCNA1 gene, the gene that produces the Kv1.1 protein.

A Changing Gene Therapy Landscape

The $33 million Series A follows a $10 million seed round EpilepsyGTx raised in 2024. The company’s three gene therapies were licensed from UCL in 2022.

The two-year timeline required to close the Series A highlights the current climate in the gene therapy sector, which has become more challenging than in previous years. Koebel, a co-founder of the sold-to-Kyowa Kirin gene therapy maker Orchard Therapeutics, noted that Orchard took only three to five months to raise a similar round nine years ago.

With the new funding, EpilepsyGTx plans to grow its current two-person team to 10 to 15 employees by the end of next year, adding a Chief Medical Officer and promoting scientific co-founder Dimitri Kullmann to Chief Scientific Officer.

EpilepsyGTx joins other biopharmas, including uniQure, UCB, Kriya, and GEMMABio, showing interest in novel approaches for epilepsy, though some—like Spark Therapeutics—have backed out of collaborations in the space. The company’s focus on an AAV-mediated gene therapy represents a cutting-edge approach to a condition with a massive unmet need.