Radium 223: How Can We Optimize This New Tool for Metastatic Castration-Resistant Prostate Cancer?

Abstract

Radium 223 is an alpha-emitting intravenous radiotherapy approved for the treatment of men with metastatic castration-resistant prostate cancer (mCRPC). The approved indication covers men with pain from bony metastatic disease and no visceral involvement; however, questions remain as to optimal patient selection and timing of this treatment relative to other life-extending therapies for mCRPC. Limited data exist to guide clinicians on how to position radium 223 in the therapeutic sequence, however, some theoretical considerations and data derived from the ALSYMPCA trial populations pre- and postdocetaxel will be outlined. Subgroup analyses may provide some insight into patient selection.KEY POINTSRadium 223 delays time to symptomatic skeletal-related events and prolongs overall survival for men with mCRPC and more than two bone metastases with pain attributed to bone metastases.Greater benefit may occur in subgroups of men with more than six bone metastases and elevated serum alkaline phosphatase over 220 U/L.There is a modestly higher rate of hematologic toxicity in men receiving radium 223 after previous docetaxel therapy, but no data exist regarding the effect of radium 223 on bone marrow reserve for subsequent chemotherapy.Follow-up data are limited regarding the possibility of long-term myelosuppression and secondary myelodysplasia or leukemia.Prostate-specific antigen changes should not be used to determine response to treatment or duration of treatment.