The role of radium-223 in the evolving treatment landscape of metastatic castration-resistant prostate cancer: A narrative review

The treatment of metastatic castration-resistant prostate cancer (mCRPC) has been rapidly evolving over the last two decades. The advent of new androgen receptor pathway inhibitors (ARPIs) such as abiraterone acetate or enzalutamide marks a great advance for treating mCRPC patientd in the pre- and post-docetaxel settings. The subsequent approval of ARPIs in early stages—i.e., metastatic hormone-sensitive (mHSPC) or nonmetastatic CRPC—led to a realignment of subsequent treatment choices upon progression to mCRPC, given the possibility of cross-resistance between ARPIs. Therapies with mechanisms of action different from those of ARPIs are now the focus of new treatment developments. Also, this anomalous situation brings the focus back to well-known treatments currently used later in the treatment sequence. This is the case of radium-223 which, when administered with enzalutamide, has recently been shown to prolong radiographic progression-free survival vs. enzalutamide alone in the first line in asymptomatic or mildly symptomatic patients with no known visceral metastases. In this narrative review, we summarize the treatment landscape for mCRPC, both from a historical and practical point of view, to understand the new potential of radium-223 as a treatment option in this setting.