Researchers reported that blood ctDNA profiling can better select patients with metastatic castration-resistant prostate cancer (mCRPC) for radium-223 (^223Ra) radiopharmaceutical therapy. A study in the July issue of The Journal of Nuclear Medicine described a framework in which ctDNA signals identify those most likely to benefit. The approach aims to reduce trial-and-error in radioisotope treatment selection by aligning therapy with tumor biology detected in circulating DNA, supporting a broader shift toward biomarker-guided use of targeted radiopharmaceuticals.