Favorable Response of 225Ac-PSMA in the Treatment of Castration-Resistant Prostate Cancer With High Bone Metastasis Burden

225 Ac-PSMA treatment demonstrated low hematologic toxicity for prostate cancer with diffuse red marrow infiltration. A 70-year-old man with diffuse bone metastases of castration-resistant prostate cancer received 225 Ac-PSMA radiation therapy. After 1 treatment cycle, the patient's skeletal lesions demonstrated a significant response and a significant decrease in PSA. 225 Ac-PSMA may be a promising therapeutic option for metastatic castration-resistant prostate cancer patients with high bone metastatic burden.