The hypothesis investigators will test in this study is whether layering radium-223 following 16 weeks of enzalutamide or darolutamide exposure in patients demonstrating a biochemical response improves disease outcomes. By adding radium-223 following a potential bone flare phenomenon [after first 12-14 weeks of therapy with an androgen receptor blocker (ARB)], including patients expected to have durable response to systemic therapy, and mandating the use of bone protective agents during treatment, the investigators aim to demonstrate an optimal time to add radium-223 in the mCRPC landscape.
This is a randomized, multi-center, double-blind, Phase III study of radium-223 plus enzalutamide or darolutamide compared to enzalutamide or darolutamide treatment plus placebo.