City Therapeutics announced on June 8 a $99.5 million Series B financing round to support the development of its RNA interference (RNAi) medicines pipeline. The company said the new funds will be used to advance its lead asset, CITY-FXI, which is in Phase 1 development for thromboembolic diseases and is designed to prevent blood clots without increasing bleeding risk.
According to City Therapeutics, CITY-FXI targets the coagulation protein Factor XI. In addition to this program, the company is developing a therapy for Stargardt disease and three other undisclosed targets, though these have not yet entered clinical trials. The funding will also support City’s next-generation RNAi engineering platform and other business development activities.
City Therapeutics launched in October 2024 with $135 million in Series A funding. Its mission is to develop next-generation small interfering RNA (siRNA) medicines for diseases that are not typically addressed by traditional RNAi approaches. John Maraganore, former CEO of Alnylam Pharmaceuticals, co-founded City and serves as executive chairman; Andy Orth is the CEO.
The company’s technology relies on trigger molecules paired with targeting ligands intended to deliver payloads across a wide range of tissue types beyond just the liver. This approach aims to expand the reach of RNAi therapies.
In May 2025, Biogen entered into a research partnership with City worth up to $1 billion for an undisclosed central nervous system disease therapy based on City’s platform. The Series B round includes backing from Regeneron Ventures, ARCH Venture Partners, Rock Springs Capital, Sofinnova Investments, and Viking Global Investors.
Maraganore said in a prepared statement, “This Series B financing reflects the exceptional progress our team has made in delivering on our mission to lead the next generation of RNAi-based medicines.” He added, “The advances our team is making with our next-generation RNAi platform speak to the breadth of what is possible beyond traditional RNAi.”
