[Ac-225]RTX-2358

[Ac-225]RTX-2358 is a novel fibroblast activation protein (FAP)-targeted radioligand therapy developed by Ratio Therapeutics. It consists of a high-affinity FAP-binding ligand conjugated to the alpha-emitting radioisotope actinium-225. FAP is highly expressed on cancer-associated fibroblasts (CAFs) in the stroma of many solid tumors and directly on the tumor cells of soft tissue sarcomas. The drug is designed for prolonged tumor residence and limited uptake in normal tissues, allowing for the delivery of high-energy alpha particles that induce double-stranded DNA breaks and potent cytotoxic effects. It is currently being evaluated in the Phase 1/2 ATLAS study for patients with relapsed or refractory soft tissue sarcoma who show FAP expression on PET imaging.