[Development and Evaluation of At-211 Labeled Peptides]

Astatine-211 (²¹¹At) has recently attracted significant attention as one of promising alpha-emitting radionuclides for targeted alpha therapy (TAT), owing to its favorable physical and chemical properties. As a halogen element located below iodine in the periodic table, ²¹¹At enables the adaptation of existing radioiodination techniques. It means potential for applications in radiotheranostics by combining ²¹¹At-labeled agents with iodine-123/124 (^123/124I)-labeled agents. Additionally, ²¹¹At has a relatively short half-life of approximately 7.2 h, making it well-suited for use with tumor-targeting small molecules or peptides that rapidly accumulate in tumors. Here, the development of a ²¹¹At-labeled peptide using arginylglycylaspartic acid (RGD) peptide as a model targeting ligand is reviewed.