Apertura Gene Therapy and Viralgen partner to manufacture blood-brain barrier-crossing AAV capsid for CNS gene therapy

Apertura Gene Therapy and Viralgen, a contract development and manufacturing organization based in San Sebastián, Spain, have entered a manufacturing collaboration centered on TfR1 CapX, a next-generation AAV capsid engineered to cross the blood-brain barrier for CNS gene therapy delivery (announcement). New York-based Apertura developed the gene therapy capsid at the Broad Institute of MIT and Harvard. Viralgen, a subsidiary of AskBio within the Bayer AG group, will provide GMP manufacturing services to support Apertura's licensees as they advance programs toward clinical trials.

Financial terms of the collaboration were not disclosed. The arrangement appears structured as a manufacturing services partnership rather than a traditional licensing deal with upfront payments, milestones, or royalties. Viralgen will supply plasmid production, Master Cell Bank creation, process optimization, fill-finish, and quality control testing for TfR1 CapX-based programs. No equity component was described.

Deal context

TfR1 CapX is an intravenously administered AAV capsid that binds human transferrin receptor 1, exploiting receptor-mediated transcytosis to shuttle gene therapy payloads from the bloodstream into the brain and spinal cord. This mechanism addresses a central limitation of conventional AAV vectors such as AAV9, which achieve poor and inconsistent CNS penetration when dosed systemically and often require invasive intrathecal injection. Apertura describes TfR1 CapX as a second-generation capsid with improved CNS delivery compared to the first-generation BI-hTFR1 vector published by the Deverman Lab. Preclinical testing has shown selectivity for CNS tissue over peripheral organs, with transduction of neurons and astrocytes across multiple brain regions. All programs using the capsid remain preclinical. Apertura has stated that multiple partner programs are expected to enter clinical trials in 2026 and 2027, though no IND filings or clinical trial registrations have been disclosed.

For Apertura, the collaboration with Viralgen secures scalable GMP manufacturing infrastructure for a platform that now underpins at least seven disclosed partnerships. Licensees include Galibra Neuroscience, which is developing a gene replacement therapy for succinic semialdehyde dehydrogenase deficiency; Emugen Therapeutics, working on neurodevelopmental and neurodegenerative programs; and the Rett Syndrome Research Trust. Apertura also maintains internal programs in genetic epilepsy and tuberous sclerosis complex, both at the IND-enabling stage. The company launched an academic access program called Open Apertura in February 2026, providing the capsid to researchers at no cost under material transfer agreements. For Viralgen, the deal adds a differentiated AAV capsid to its manufacturing portfolio. The CDMO has produced more than 1,500 AAV batches across its three 2,000-liter cGMP suites certified by the Spanish medicines agency and EMA.

The BBB-crossing AAV capsid space includes several competing platforms at various stages:

• VCAP-102 — Voyager Therapeutics — IND-enabling; targets alkaline phosphatase for BBB transcytosis; partnered with Novartis and Neurocrine Biosciences
• Engineered capsids — Capsida Biotherapeutics (acquired by Novartis) — IND-enabling; automated NHP-driven capsid evolution
• CapsidMap capsids — Dyno Therapeutics — preclinical; AI-designed capsids including TfR1-targeting variants; partnered with Novartis, Roche, and Sarepta
• AAVhs series — Passage Bio — Phase 1/2 for GM1 gangliosidosis and Krabbe disease; Penn-derived capsids

No clinical data exist for any TfR1-targeting engineered AAV capsid in human patients. Whether TfR1-mediated transcytosis or alternative receptor pathways will prove more effective in clinical settings remains unresolved.

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