Estuary Biotherapeutics launched with $103 million to develop locally delivered AAV gene therapies aimed at autosomal dominant polycystic kidney disease (ADPKD). The financing includes a $93 million Series A led by RA Capital Management plus a $10 million seed round co-led by 4BIO Capital and GV. The company says it will advance two lead programs through clinical proof-of-concept and expand its kidney-targeting platform. Both therapies are intended to restore polycystin levels across the nephron by delivering gene therapies that address the genes behind more than 90% of ADPKD cases. Estuary positions the approach as differentiated from currently approved disease-modifying care, citing that Otsuka’s tolvaptan slows progression without correcting the underlying cause. Its strategy targets delivery as the central barrier to effective gene therapy in inherited kidney disease. If successful, the company’s platform could reshape how locally administered AAV treatments are designed for organ-specific gene replacement, particularly for nephron-level distribution challenges.