Response to ²²³Ra-dichloride in castration-resistant prostate cancer with bone metastasis: A case report

Painful bone metastases are common in prostate cancer, with current treatments including non-steroidal analgesics and opiates, surgery, external beam radiotherapy and bone-targeting β-emitting radiopharmaceuticals. The α-emitting isotope ²²³Ra-dichloride (Ra-223) has been associated with improved overall survival and increased time to first skeletal-related events in patients with castration-resistant prostate cancer (CRPC) presenting with symptomatic bone metastases. The current study reports the case of a 70-year-old male patient, who was diagnosed with prostate cancer in 1999 upon presentation with increased prostate-specific antigen (PSA) levels and painful bone metastases in the context of CRPC. In November 2010, subsequent to undergoing hormonal blockage, the patient was treated with ketoconazole (200 mg/8 h) followed by 10 cycles of docetaxel (75 mg/m² every 3 weeks). Following disease progression, the patient received 6 doses of Ra-223 (50 kBq/kg; 1 dose/4 weeks). During this treatment period, an improvement in the patient's symptoms, and levels of bone alkaline phosphatase (BAP) and PSA were noted. Furthermore, Ra-223 was well-tolerated without any relevant bone marrow toxicity. However, 2 months after the administration of the final dose of Ra-223, PSA and BAP levels increased again, and bone pain deteriorated. A bone scan showed stable disease in the previously observed metastatic lesions; however, new lesions simultaneously appeared in different locations, indicating progressive disease.