(UroToday.com) In this poster, the authors presented efficacy and safety results from a phase 2 single-center randomized study of enzalutamide monotherapy versus combination enzalutamide and radium-223 in progressive metatstatic castration-resistant prostate cancer (mCRPC). This combination has been previously published as being safe and resulting in PSA declines that correlated with reductions in bone metabolic markers (10.1158/1078-0432.CCR-19-2591). Treatment consisted of 160 mg daily enzalutamide with or without standard radium-223 dosing every 4 weeks up to six treatments. Outcomes presented in this poster included PSA progression free survival, overall survival, PSA-PFS2, time to next therapy, and long term safety. Of all outcomes reported, the combination was shown to statistically significantly improve PSA-PFS2 relative to enzalutamide alone (18.7 months versus 8.4 months, p = 0.033). Overall survival, PSA PFS, rPFS and time to next treatment were numerically superior in the combination arm, but these differences were not statistically significant.