# Ratio Therapeutics

Source: https://onco.cc/companies/ratio-therapeutics/  
OnCo record `ratio-therapeutics` (Company). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Ratio Therapeutics, of Boston, designs small molecules that carry a radioactive isotope to fibroblast activation protein, a protein on the supporting tissue of sarcomas and other solid tumours, so radiation is delivered from inside the body. Its lead, an actinium-225 radioligand, is in the ATLAS phase 1/2 trial in advanced sarcomas.

## Summary

Ratio Therapeutics is a clinical-stage Boston radiopharmaceutical company whose Trillium targeting scaffold combines pharmacokinetic modulation with chelation chemistry to create small-molecule radioligands that can be paired with imaging or therapeutic isotopes (theranostics). The lead programme [Ac-225]RTX-2358 is a fibroblast activation protein (FAP)-targeted actinium-225 therapeutic in the ATLAS phase 1/2 trial in advanced sarcomas; the pipeline also includes a next-generation GRPR programme and additional mono- and bispecific radioligands, with a fifth IND filing in preparation. In July 2026 Ratio closed a USD 70 million Series C with Duquesne Family Office, Bristol Myers Squibb, Catalio Capital, Eli Lilly and Wasatch Group, taking total capital raised above USD 240 million. It has manufacturing collaborations with PharmaLogic, an actinium-225 supply agreement with PanTera (June 2026) and, in September 2026, a research collaboration and licence agreement with RayzeBio.

## Fields

- Kind: Company
- Last checked: 2026-09-10
- HQ: Boston, MA
- Type: radiopharma
- Website: https://ratiotx.com/

## Notes

- Earlier rounds (Series A and B) not fetched and omitted.

## Sources

- Official website: https://ratiotx.com/
- Series C press release: https://ratiotx.com/2026/07/31/ratio-therapeutics-closes-70-million-series-c-financing-to-advance-clinical-development-of-targeted-radiotherapeutics-pipeline-and-expand-manufacturing-infrastructure/
- News: https://ratiotx.com/news1/

## Connected records

- cancers: [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/)
- fronts: [Radiopharmaceuticals & Theranostics](https://onco.cc/fronts/radiopharma/)
- technologies: [Radioligand therapy (beta emitters)](https://onco.cc/technologies/radioligand-therapy/), [Targeted alpha therapy](https://onco.cc/technologies/targeted-alpha-therapy/)
- targets: [FAP](https://onco.cc/targets/fap/)

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