A scalable protocol for the radiosynthesis of clinical grade lutetium-177-labeled theranostic agents.

Abstract

Theranostics utilizes tandem targeted diagnostic and therapeutic agents that are molecularly analogous. In a theranostic approach, the diagnostic agent is a tracer typically radiolabeled with a positron emission tomography radionuclide such as fluorine-18 or gallium-68. Utilizing the selectivity of the tracer, the therapeutic agent is subsequently radiolabeled with an ablative radionuclide such as the β^- emitting lanthanide lutetium-177 (¹⁷⁷Lu). ¹⁷⁷Lu is typically incorporated into theranostics using the chelators 2,2',2'',2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) and 2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioic acid (DOTAGA) that are used to prepare the ¹⁷⁷Lu-radiopharmaceutical [¹⁷⁷Lu]Lu-DOTA-TATE, [¹⁷⁷Lu]Lu-PSMA-617 and [¹⁷⁷Lu]Lu-PSMA-I&T. Here we describe the scalable and validated production for these ¹⁷⁷Lu-radiopharmaceuticals and further include the necessary quality control protocols. The procedures can be generalized and support both carrier added and noncarrier added ¹⁷⁷Lu sources for use in a clinical setting. With robust procedures that accommodate ¹⁷⁷Lu activity levels from 5 to 100 GBq, the procedures ensure stability for up to 8 h postproduction and achieve an average activity yield of 98%. As proven in over 1,000 patient cycles, this methodology is adaptable to both centralized production facilities and regional centers, enabling versatile application across small and large-scale production settings.