Applications of (211) At and Ra-223 in Targeted Alpha-Particle Radiotherapy

Targeted radiotherapy using agents tagged with alpha-emitting radionuclides is gaining traction with several clinical trials already undertaken or ongoing, and others in the advanced planning stage. The most commonly used alpha-emitting radionuclides are Bi-213, At-211, Ra-223 and Ac-225. While each one of these has pros and cons, it can be argued that At-211 probably is the most versatile based on its half life, decay scheme and chemistry. On the other hand, for targeting bone metastases, Ra-223 is the ideal radionuclide because simple cationic radium can be used for this purpose. In this review, we will discuss the recent developments taken place in the application of (211) At-labeled radiopharmaceuticals and give an overview of the current status of Ra-223 for targeted alpha-particle radiotherapy.