Engineering TfR1 binding CNS targeted AAV capsids that evade pre-existing neutralizing antibodies

Adeno-associated virus (AAV) gene therapy shows promise for treating numerous severe CNS disorders that currently lack disease-modifying treatments. However, its widespread application is hindered by delivery efficiency challenges and pre-existing neutralizing antibodies (NAbs) against the AAV capsid. Our group recently developed a novel AAV capsid, BI-hTFR1, that efficiently crosses the blood-brain barrier (BBB) and delivers genes to neurons and glia throughout the CNS after systemic administration. This capsid functions by interacting with the human transferrin receptor (TfR1), a protein that mediates transport of iron-loaded transferrin into cells and across the BBB via receptor-mediated transcytosis. BI-hTFR1 and its later-generation variants efficiently deliver genes throughout the brains of mice modified to express a humanized TFRC gene, but show no enhanced delivery in mice expressing mouse TfR1. While BI-hTFR1 enables brain-wide gene delivery, it remains sensitive, like natural AAVs, to neutralizing antibodies present in 40-80% of individuals. This sensitivity limits the pool of patients who could benefit from these transformative gene therapies. Our proposal aims to develop AAV capsids that evade NAbs while maintaining their previously engineered TfR1-dependent tropism enhancement. In preliminary experiments, we have demonstrated that our NAb evasion engineering strategy has generated TfR1-binding capsids that can fully evade neutralization in over 40% of human sera samples containing antibodies that neutralize AAV9 and AAV5. In this project, we will use a suite of established and new screening assays to develop TfR1-binding capsids that evade antibody neutralization in the vast majority of patients while retaining their TfR1-dependent CNS tropism enhancement and scalable manufacturability. The capsids resulting from this effort will expand the pool of eligible patients for CNS gene therapy and will be made available to the wider research community. Project Number: 1R61NS146351-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Neurological Disorders and Stroke (NINDS) | Principal Investigator: Benjamin Deverman | Institution: BROAD INSTITUTE, INC., CAMBRIDGE, MA | Award Amount: $404,282 | Activity Code: R61 | Study Section: Special Emphasis Panel[ZRG1 NV-F (51)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11288689