Estuary Biotherapeutics launched with $103 million in financing to develop locally delivered AAV gene therapies for autosomal dominant polycystic kidney disease (ADPKD). The company’s approach targets the kidney directly, aiming to restore polycystin levels across the nephron with potentially one-time administration. The funding included a $93 million Series A led by RA Capital Management, plus a $10 million seed co-led by 4BIO Capital and GV. Investors also included Deep Track Capital, Biogen New Ventures, the National Kidney Foundation Innovation Fund, and a family office linked to an ADPKD patient. Regulatory and clinical differentiation centers on delivery. With tolvaptan remaining the only FDA-approved ADPKD drug and acting downstream rather than correcting the underlying cause, Estuary’s platform is designed to address what it describes as the key barrier to kidney gene therapy: getting the vector to the right cells in the right place.