Radium-223 in patients with metastatic castration-resistant prostate cancer: Efficacy and safety in clinical practice

Radium-223 has improved overall survival (OS) and reduced symptomatic skeletal events (SSE) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases (ALSYMPCA trial). Our aim was to assess clinical and biochemical factors related to survival, safety and survival outcomes of Radium-223 in a clinical practice setting. We retrospectively analysed 32 mCRPC patients treated with Radium-223, assessing bone scan, pain reduction, alkaline phosphatase (ALP) and prostate-specific antigen (PSA) response (≥30% reduction). At scintigraphic assessment, 41% had partial response with a disease control rate of 91%; 56% had ALP response and 25% had PSA response; 41% had pain reduction with pain control of 72%. Scintigraphic response and stability were correlated with longer median progression-free survival (mPFS) (13 and 12 vs. 6 months; P=0.002) and mOS (16 and 12 vs. 6 months; P=0.003). ALP response was associated with longer mPFS (13 vs. 12 months; P=0.2) and mOS (16 vs. 12 months; P=0.2). PSA response was associated with longer mPFS (13 vs. 12 months; P=0.02), whereas mOS could not be computed. Pain response and stability were associated with survival benefit according to mPFS (13 and 12 vs. 9 months) and mOS (both 16 vs. 12 months) without statistical significance. Baseline ALP <220 UI/l, Eastern Cooperative Oncology Group (ECOG) performance status 0 and absence of previous chemotherapy correlated with statistically significantly longer survival outcomes. Skeletal-related events (SRE) occurred in three patients and median time to first SRE was 9.5 months, mPFS was 12 months and mOS 14 months. G3-G4 toxicities developed in 16% of patients. Our results are in line with those reported in the pivotal trial and in other retrospective studies. In conclusion, Radium-223 was associated with high scintigraphic, biochemical and pain response rates and was tolerated well by most patients. Response to Radium-223 and better baseline factors correlated to longer survival in clinical practice experience as in the clinical trial setting.