Ratio Therapeutics has expanded its manufacturing collaboration with radiopharmaceutical CDMO PharmaLogic Holdings Corp., to scale clinical supply of [Ac-225]RTX-2358, its lead FAP-targeted alpha-emitting radioligand therapy currently in the Phase I/II ATLAS trial for relapsed or refractory soft tissue sarcoma. The expansion adds PharmaLogic's Idaho Falls therapeutics facility to the manufacturing network and introduces larger-scale multi-dose batch production capabilities. Financial terms were not disclosed.
The expanded scope is designed to support ongoing clinical supply for ATLAS and to position the program for potential registrational trials. Ratio, which also operates its own manufacturing facility in Salt Lake City, Utah, is building redundant production infrastructure — a practical necessity for Actinium-225-based therapies, where isotope supply chain complexity and radiolabeling constraints make single-site dependency a material risk.
Deal context
[Ac-225]RTX-2358 is a small molecule FAP-targeted radiotherapeutic built on Ratio's proprietary Trillium and Macropa platforms. The Trillium scaffold incorporates a reversible albumin-binding motif that extends plasma circulation time and increases cumulative tumor radiation dose, while the Macropa macrocyclic chelator enables stable Actinium-225 complexation at room temperature — a meaningful manufacturing advantage over the conventional DOTA chelator, which requires temperatures above 90°C for adequate Ac-225 labeling. Ratio describes the compound as engineered for high tumor uptake and prolonged retention, with optimized plasma clearance to limit off-target radiation exposure.
The ATLAS trial is an open-label Phase I/II study evaluating safety, tolerability, dosimetry, biodistribution, pharmacokinetics, and anti-tumor activity in FAP-expressing soft tissue sarcoma.
FAP is a serine protease overexpressed on cancer-associated fibroblasts across multiple solid tumor types, making it an attractive pan-tumor target. Other FAP-directed radiopharmaceuticals in development — including programs using Lu-177 beta-emitting payloads — have generated broad industry interest, but Ratio's use of Actinium-225, an alpha emitter with high linear energy transfer and short path length, is intended to deliver more potent, localized cytotoxicity.