Bone-targeting radiopharmaceuticals for the treatment of bone-metastatic castration-resistant prostate cancer: Exploring the implications of new data

Background: Clinical features of patients with castrationresistant prostate cancer (CRPC) are characterized by a high incidence of bone metastases, which are associated with impairment of quality of life, pain, skeletal-related events (SREs), and a negative impact on prognosis. Advances in the understanding of cancer cell-bone stroma interactions and molecular mechanisms have recently permitted the development of new agents. Purpose: Wereview the merits, applications, and limitations of emerging data sets on bone-metastatic CRPC with a focus on radium-223, an a-emitting radiopharmaceutical, and its use in therapy for this disease. Methods: References for this review were identified through searches of PubMed and Medline databases, and only papers published in English were considered. Related links in the databases were reviewed, along with relevant published guidelines, recently published abstracts from major medical meetings, and transcripts from a recent round table of clinical investigators. Results: Prior to radium-223, available bone-targeted therapies demonstrated the ability to delay SREs and palliate bone pain in patients with metastatic CRPC but without evidence of improvement in overall survival (OS). In a randomized controlled phase III trial, radium-223 demonstrated the ability to improve OS and delay SREs in docetaxel-pretreated or docetaxel-unfit men with symptomatic bone-metastatic CRPC and was not associated with significantly more grade 3 or 4 adverse events than placebo.Conclusion: Radium-223 has a targeted effect on bone metastases in CRPC and has an important role in docetaxel-pretreated or docetaxel-unfit menwith symptomatic bone-metastatic CRPC.