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.