Estuary Biotherapeutics has officially launched with a 93 million dollar Series A round, BioPharma Dive reported, to develop gene therapies for autosomal dominant polycystic kidney disease, or ADPKD, an inherited disorder in which cysts progressively damage the kidneys and often lead to renal failure. The condition affects roughly one in every 400 to 1,000 people, and only one drug, tolvaptan, is specifically approved to treat it, slowing rather than reversing the disease.
The science comes from Yale, where co-founders Stefan Somlo and Michael Caplan showed in mice that reactivating proteins called polycystins could shrink cysts and reverse kidney inflammation and scarring, and that only a small piece of the full polycystin protein is needed to suppress the disease. That second finding matters for delivery: helpful genetic material small enough to package into standard viral vectors could reach the kidney, which chief executive Wayne Sackett called the most crucial remaining barrier to kidney gene therapy.
Estuary’s two lead programmes attack the disease’s two main genetic drivers. EST-201 delivers a full length version of the PKD2 gene’s product, while EST-101 delivers the most useful portion of the PKD1 protein; both are designed as one time, locally administered treatments, with human testing expected in 2027 and 2028 respectively.
The round was led by RA Capital Management, with participation from Deep Track Capital, 4BIO Capital, GV and Biogen’s early stage investment arm, and the management team is stocked with former Biogen leaders. Estuary is not alone in the indication: Novartis agreed last year to acquire Regulus Therapeutics for 800 million dollars for an RNA targeting ADPKD medicine, and Renasant Bio emerged with 55 million dollars in seed funding for its own approach.