225Ac-RTX-2358

**225Ac-RTX-2358** is a targeted radiopharmaceutical in early clinical development by Ratio Therapeutics for treating advanced solid tumors, particularly soft tissue sarcoma. It consists of Actinium-225 (**225Ac**), an alpha-emitting radioisotope, conjugated to RTX-2358, a radioligand that specifically targets **fibroblast activation protein (FAP)**, which is overexpressed in the tumor stroma of many cancers. The alpha particles deliver high-energy, short-range radiation to destroy cancer cells with minimal damage to surrounding healthy tissue. It is being evaluated in the **ATLAS trial (NCT07156565)**, a seamless Phase 1/2 study assessing safety, tolerability, dosimetry, pharmacokinetics, and antitumor activity, with dosing every 8 weeks for up to 6 cycles over 12 months, paired with the diagnostic agent **[Cu64]LNTH-1363S**.

Other names

[Ac 225]-RTX-2358