# City Therapeutics

> City Therapeutics is a Cambridge, Massachusetts biotechnology company engineering the next generation of RNA interference (RNAi) medicines. Founded by pioneers of the RNAi field, including former Alnylam CEO John Maraganore and Nobel-adjacent academic scientists, the company designs novel siRNA trigger molecules and targeting ligands intended to make RNAi drugs more potent, more specific, and able to reach tissues beyond the liver. Launched in October 2024 with a $135M Series A and backed by a further $99.5M Series B in 2026, City is advancing a pipeline led by CITY-FXI for thromboembolic disease and CITY-RBP4 for Stargardt disease, alongside research collaborations with Biogen and Bausch + Lomb.

- **Founded:** 2024
- **Headquarters:** Cambridge, Massachusetts, United States
- **Founders:** John Maraganore (Executive Chair & Co-founder (former founding CEO of Alnylam)), Sebastian Trousil (Chief Operating Officer & Co-founder), Ari Nowacek (SVP Corporate Development & Co-founder (ARCH Venture Partners)), Robert Nelsen (Co-founder & Board Member (ARCH Venture Partners)), Phillip D. Zamore (Scientific Co-founder (UMass Chan Medical School; Alnylam co-founder)), Kotaro Nakanishi (Scientific Co-founder (The Ohio State University)), Yukihide Tomari (Scientific Co-founder (University of Tokyo)), Mark Keating (Co-founder)
- **Team size:** ~78 employees (2026)
- **Products:** RNAi engineering platform, CITY-FXI, CITY-RBP4
- **Notable:** Launched in October 2024 with a $135M Series A led by ARCH Venture Partners., Assembled a founding team of RNAi pioneers including former Alnylam CEO John Maraganore., Advanced lead program CITY-FXI into a Phase 1 clinical trial within roughly a year of launch.

## Products & services

- **RNAi engineering platform** — A discovery engine built around novel RNAi trigger designs - including 'cleavage-inducing tiny (city) RNAs' - and customized targeting ligands intended to improve potency and specificity and to deliver siRNA beyond the liver to additional cell and tissue types.
- **CITY-FXI** — An investigational RNAi therapy targeting Factor XI (FXI) for thromboembolic diseases; the company's lead program, now in a Phase 1 clinical trial.
- **CITY-RBP4** — An investigational RNAi therapy designed to silence hepatic expression of RBP4, the vitamin A (retinol) carrier, as a potential first-in-class treatment aimed at slowing progression of Stargardt disease.

## Achievements

- Launched in October 2024 with a $135M Series A led by ARCH Venture Partners.
- Assembled a founding team of RNAi pioneers including former Alnylam CEO John Maraganore.
- Advanced lead program CITY-FXI into a Phase 1 clinical trial within roughly a year of launch.
- Signed strategic research collaborations with both Biogen and Bausch + Lomb.
- Closed a $99.5M Series B in 2026 with new investors including Viking Global and Sofinnova.
- Presented preclinical data on CITY-RBP4 for Stargardt disease at the ARVO 2026 Annual Meeting.

## Latest updates

- **2026-06** — Announced a $99.5M Series B financing to advance its next-generation RNAi pipeline and engineering platform.
- **2026-05** — Presented preclinical data on CITY-RBP4 for Stargardt disease at the ARVO 2026 Annual Meeting.
- **2025** — Advanced lead candidate CITY-FXI into a Phase 1 clinical trial for thromboembolic disease.
- **2024-10** — Launched publicly with $135M Series A financing led by ARCH Venture Partners.

## Links

- Website: https://citytx.com
- LinkedIn: https://www.linkedin.com/company/city-therapeutics
- Twitter/X: https://x.com/CityTx_

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Profile page: https://yespress.io/city-therapeutics
Published by YesPress — https://yespress.io
Last updated: 2026-07-22