Estuary Biotherapeutics, a California-based genetic medicines company, launched with $93 million in Series A funding to develop gene therapies for autosomal dominant polycystic kidney disease (ADPKD). The round was led by RA Capital Management and included Biogen's early-stage investment arm, among others.
The company's science is based on Yale research showing that reactivating polycystin proteins can shrink cysts and reverse kidney damage in mice. Estuary's two lead programs, EST-201 and EST-101, aim to deliver functional versions of the PKD2 and PKD1 genes, respectively, through one-time local administration. The company expects to enter human testing in 2027 and 2028.
ADPKD affects roughly 1 in 400 to 1,000 people, and only tolvaptan is specifically approved to treat it. Estuary's CEO said patients are still awaiting a therapy that can transform the disease course. Other developers are also active: Novartis agreed to acquire Regulus Therapeutics, and Renasant Bio emerged with $55 million, while Sanofi's candidate failed a key study.