Work

AAV9-Mediated Gene Replacement Therapy for CTNNB1-Related Neurodevelopmental Disorder

Year: 2026

Type: preprint

Abstract: CTNNB1 Syndrome is a severe neurodevelopmental disorder caused by haploinsufficiency of the CTNNB1 gene, which encodes β-catenin, a central regulatory protein of the canonical Wnt signaling and nervous systems development. Today affected patients experience global developmental delays (GDD), intellectual disability, and progressive motor impairments, with no disease-modifying treatment available. We developed and evaluated the first gene therapy targeting CTNNB1 Syndrome based on recombinant adeno-associated virus (rAAV). Six therapeutic cassettes were engineered and screened in patient-derived cortical brain organoids, identifying the lead candidate that restores β-catenin function with downstream pathway normalization. The selected vector was evaluated in a mouse model recapitulating motor and behavioral symptoms of the CTNNB1 Syndrome patients. To do so, juvenile CTNNB1 Syndrome mice received escalating unilateral intracerebroventricular doses of the vector. Mice treated with the highest dose showed improved locomotor and anxiety-related behaviors, with no adverse effects over eight months. Drug material for toxicology and biodistribution studies was manufactured under current Good Manufacturing Practice (cGMP) conditions. Safety, biodistribution and tolerability were further assessed in wild-type mice and non-human primates (NHPs), of which some mice toxicology and biodistribution analyses were conducted under Good Laboratory Practice (GLP) and in compliance with the European Medicines Agency (EMA) regulatory requirements. Following infusion of animals with the drug candidate, no treatment-related clinical, biochemical or histopathological adverse findings were observed and the No Observed Adverse Effect Level (NOAEL) was established at the highest vector dose. These findings support the preclinical safety and therapeutic efficacy in AAV9-mediated β-catenin gene augmentation therapy, paving the way for a clinical trial in Europe, already initiated in December 2025.

Source: Research Square

DOI: 10.21203/rs.3.rs-10408032/v1