4CPS-191 Effectiveness and safety of radium-223 chloride in bone-metastatic castration-resistant prostate cancer

Background Radium-223 ( 223 Ra) chloride has been shown to improve overall survival (OS) and progression-free survival (PFS) in patients with castration-resistant prostate cancer (CRPC) and bone metastases. Purpose To evaluate the effectiveness and safety of 223 Ra in real-life clinical practice in patients with CRPC and bone metastases. Material and methods Retrospective observational multicentre study evaluating all males with CRCP treated with 223 Ra from July 2015 until September 2018. Demographical, diagnostic, therapeutic and clinical variables were collected. The response was assessed through the PFS and OS. To assess safety, all treatment-related adverse events were recorded. Results Sixty-three patients with metastatic CRPC were treated with 223 Ra at three different hospitals. Mean age 71.9 years (SD=10.3), 64% of patients ECOG 0–1% and 36% ECOG 2–3. Six per cent of patients received 223 Ra as first treatment, 48% as second line and 25% as the third one: the remaining 21% 223 Ra was used in the fourth line or higher. Thirty-seven patients completed six treatment cycles and 26 stopped treatment before completing six cycles because of side effects or worsening performance status: 223 Ra mean dose was 4.6 MBq (SD=0.7). Fifteen per cent of patients had more than a 40% reduction in PSA levels at the end of treatment. According to Kaplan–Meier estimation, median OS and PFS were 10.0 (95% CI: 8.1 to 11.9) and 5.0 (95% CI: 4.1 to 5.9) months, respectively. Six- and 12 month OS rates were 76% and 39%, respectively. Patients receiving all six cycles experienced the major benefit from the therapy. In addition, nine patients were given 223 Ra at least 1 month prior to death. Forty-nine per cent of patients suffered haematological adverse effects such as thrombocytopaenia and neutropaenia, three patients grade 3 or 4 toxic effects and 24% of patients showed gastrointestinal side effects such as diarrhoea, nausea and vomiting in grade 1–2. Fourteen patients reported a worsening of their bone pain. Conclusion PFS and OS observed in this study are lower than those reported in the clinical trial. This could be explained by a worse performance status and that approximately half of the patients had been heavily pre-treated, 223 Ra receiving as a third line or higher. 223 Ra was well tolerated, the adverse effects being clinically manageable. References and/or acknowledgements No conflict of interest.