Recent Advances in Preclinical Studies of the Theranostic Agent [ 64 Cu]CuCl 2 .

64 Cu is gaining recognition not only for its diagnostic capabilities in nuclear medical imaging but also for its therapeutic and theranostic potential. The simultaneous β- and Auger emissions of 64 Cu can be utilized to induce a therapeutic effect on cancerous lesions. The finding of the exceptional biodistribution characteristics of the radionuclide 64 Cu, when administered as basic copper ions, has highlighted its potential therapeutic application in cancer treatment. Preclinical and clinical research on the effectiveness of [ 64 Cu]CuCl 2 as a theranostic radiopharmaceutical has commenced only in the past decade. Current clinical studies are increasingly demonstrating the high specificity and uptake of [ 64 Cu]Cu 2+ by malignant tissues during early cancer progression, indicating its potential for early cancer diagnosis across various organs. This short review aims to present the latest preclinical studies involving [ 64 Cu]CuCl 2 , offering valuable insights for researchers planning new in vitro and in vivo studies to explore the theranostic potential of [ 64 Cu]Cu 2+ .