Estuary Biotherapeutics

Biotech · Gene Therapy · Kidney Disease

Funding

Estuary Biotherapeutics raises $93M Series A for kidney gene therapy

A kidney-confined gene therapy approach aims to sidestep the systemic toxicity issues that have stalled AAV treatments elsewhere in the body.

• Estuary Biotherapeutics emerged from stealth with $103M in total financing, anchored by a new $93M Series A led by RA Capital Management, to develop gene therapies for kidney disease.
• The company is a Yale spinout built on research from Stefan Somlo and Michael Caplan of Yale School of Medicine, targeting autosomal dominant polycystic kidney disease (ADPKD).
• Lead programs EST-201 and EST-101 target the two most common genetic subtypes of ADPKD and are slated to enter clinical trials in 2027 and 2028.
• The therapies use a one-time, locally delivered AAV vector to restore polycystin protein across the kidney's nephrons, a kidney-confined design meant to avoid the systemic toxicity that has limited AAV gene therapies in other organs.
• The $93M Series A follows a $10M seed round co-led by 4BIO Capital and GV, bringing Estuary's total committed financing to $103M.
• ADPKD, a progressive inherited disease that causes kidney cysts leading to organ failure, currently has only one FDA-approved drug to slow its progression.
• Gene therapy developers have struggled to make systemic AAV delivery safe at the doses needed to treat organ-specific diseases, so a localized, kidney-only approach could open a path other programs have been unable to find.