Effectiveness and safety of radium‐223 dichloride in patients with castration‐resistant prostate cancer and bone metastases in real‐world practice: A multi‐institutional study.

Objective: Radium‐223 (Ra‐223) dichloride is the bone‐targeted radioligand therapy that prolongs overall survival (OS) in patients with bone‐metastatic castration‐resistant prostate cancer (CRPC). We aimed to evaluate the safety and effectiveness of this treatment in real‐world practice. Methods: We included Japanese men treated with Ra‐223 for bone‐metastatic CRPC from 10 institutions, retrospectively. Primary endpoint was OS. Secondary endpoint was maximum decline of alkaline phosphatase (ALP), lactate dehydrogenase, and prostate‐specific antigen values, the rate of adverse events, and time to pathological fracture after Ra‐223 treatment. Exploratory endpoint was the associations between clinical parameters and OS. Results: In total, 73 men with bone metastatic CRPC treated with Ra‐223 were enrolled. The median OS was 20.9 months. ALP levels decreased significantly from pre‐treatment (p = 0.03). Anemia occurred in three (4.1%) patients. Grade ≥ 3 non‐pathological fractures occurred in four (5.5%) men. Nine (12.3%) patients presented pathological fracture; 7/30 (23.3%) were in men without concomitant use of a bone‐modifying agent (BMA) while 2/43 (4.7%) were in patients with concomitant BMA (p = 0.03). The median OS in patients with ≥3 cycles treatment (27.2 months, p < 0.001) or hemoglobin ≥12 g/dl (27.2 months, p = 0.001) or absence of bone pain (36.3 months, p = 0.004) was significantly longer compared to those who with ≤2 cycles or hemoglobin<12 g/dl or presence of bone paint, respectively. Conclusions: This study has shown the outcomes of Ra‐223 treatment in real‐world practice, where the number of treatment cycles, baseline anemia and bone pain may be useful to predict OS in Ra‐223 treatment. [ABSTRACT FROM AUTHOR]