City Therapeutics, a Cambridge MA-based developer of next-generation RNAi therapeutics, has raised $99.5 million in Series B funding. The company engineers siRNA trigger molecules and extra-hepatic targeting ligands to create more potent and durable medicines that reach tissues beyond the liver. The capital will advance CITY-FXI into Phase 1 for clotting disorders and CITY-RBP4 for Stargardt disease while expanding the platform.
RNAi Funding Wave Accelerates
The timing aligns with renewed investor interest in RNAi. Roche licensed an RNAi therapy from SangeneBio in a deal worth up to $1.7 billion in June 2026. City’s approach uses novel cleavage chemistry and peptide ligands to target the eye and CNS, addressing delivery gaps that have constrained earlier platforms.
Liver Focus Leaves Most Tissues Untreated
Current RNAi medicines primarily reach the liver, leaving over 200 cell types without approved gene-silencing options. The RNAi therapeutics market stood at $1.28 billion in 2024 and is projected to reach $5.11 billion by 2034 at a 14.9% CAGR. Demand is rising for therapies in rare eye diseases and cardiometabolic conditions where liver delivery alone falls short.
cityRNA Triggers Enable Extrahepatic Reach
City Therapeutics is developing smaller, more potent "cityRNA" triggers paired with cell-type specific peptide ligands. CITY-FXI targets Factor XI to prevent clots without raising bleeding risk. CITY-RBP4 silences RBP4 to reduce toxic retinoid buildup in Stargardt disease via twice-yearly dosing.
As CEO Andy Orth noted:
“One reason people are so attracted to these first couple programs is because they have rock solid belief in the technology.”
This differentiates the company from Alnylam Pharmaceuticals and Arrowhead Pharmaceuticals, which focus primarily on liver and select extrahepatic targets with established chemistries.
Tier-1 Syndicate Validates Platform
Viking Global Investors and Sofinnova Investments joined as new investors with board observer roles. Existing backers ARCH Venture Partners, Regeneron Ventures, and Casdin Capital also participated. The syndicate reflects conviction in founder John Maraganore’s track record and the company’s preclinical duration-of-effect data supporting infrequent dosing.
Extrahepatic Delivery Defines Next Wave
The broader RNAi market is shifting toward CNS, muscle, and kidney targets. Public competitors include Alnylam Pharmaceuticals with over $3.2 billion in cumulative funding and Arrowhead Pharmaceuticals with over $1.1 billion. Silence Therapeutics has raised over $500 million. City’s focus on novel trigger engineering positions it for the post-liver era of RNAi medicines.
Clinical Transition Signals Momentum
City has submitted a clinical trial application for CITY-FXI and presented preclinical data for CITY-RBP4 at ARVO 2026. The company is hiring across discovery, data science, and clinical development to support multiple programs entering the clinic.
With deployments advancing toward human data, City is positioned to test whether its next-generation chemistry can expand RNAi into previously inaccessible tissues.