Development of a Nonviral Gene Therapy for X-linked Alport Syndrome by Targeted Transcutaneous Ultrasound-Mediated Gene Delivery

Background: X-linked Alport syndrome (XLAS) is a genetic condition characterized by kidney disease, as well as hearing loss and eye abnormalities. Kidney disease in XLAS is caused by a dysfunction of the glomerular basement membrane (GBM), due to a mutation in the COL4A5 gene encoding the type IV collagen a5 chain. Ultrasound mediated gene delivery (UMGD) is an effective approach for noninvasive targeted transgene delivery into kidney cells and so offers the opportunity to develop a COL4A5 gene replacement therapy for XLAS. Methods: Multiple codon-optimized COL4A5 open-reading frame sequences under control of podocyte-specific promoters were engineered and screened in vitro in primary human kidney cells with the goal of developing a podocyte-specific COL4A5 DNA construct. The top COL4A5 candidate was tested in vivo using SonoThera’s proprietary noninvasive UMGD-based gene delivery platform targeting the kidney of an XLAS mouse model. Safety of gene delivery was also evaluated using established methods. Results: Genetic engineering and in vitro screening allowed for the development of an optimized podocyte-specific COL4A5 construct, which was successfully delivered using UMGD to the kidney of the XLAS mouse model. Molecular analysis of XLAS mouse model kidney tissue samples demonstrated gene expression localized to podocytes. Established safety and tolerability endpoints were evaluated which provided an excellent safety profile without off-target delivery to liver or other non-targeted organs, supporting continued therapeutic development. Conclusion: COL4A5 expression in podocytes of the XLAS mouse model kidney along with the favorable safety profile of noninvasive targeted UMGD delivery supports translation of this approach towards clinical development for the treatment of the XLAS.