Excellent Response to Combined 223 Ra-dichloride and Enzalutamide After Failure of 177 Lu-PSMA Radioligand Therapy

We report an 81-year-old man with metastatic castration-resistant prostate cancer (mCRPC) after multiple prior therapies, including androgen deprivation therapy (ADT), the androgen receptor pathway inhibitor (ARPI) abiraterone, taxane chemotherapy with docetaxel and cabazitaxel, radiopharmaceutical therapy (RPT) with 4 cycles of [ 177 Lu]PSMA-I&T, and the PARP inhibitor olaparib in combination with abiraterone. Due to biochemical and clinical progression, [ 18 F]PSMA-1007 PET/CT was performed for restaging, revealing diffuse skeletal metastases without significant extraosseous disease. Based on this imaging pattern, treatment with the ARPI enzalutamide combined with 223 Ra-dichloride was initiated, resulting in an excellent response with a >90% PSA decline and a progression-free survival of 10 months.