Three-year Safety of Radium-223 Dichloride in Patients with Castration-resistant Prostate Cancer and Symptomatic Bone Metastases from Phase 3 Randomized Alpharadin in Symptomatic Prostate Cancer Trial.
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<h4>Background</h4>In Alpharadin in Symptomatic Prostate Cancer (ALSYMPCA) trial, radium-223 versus placebo prolonged overall survival with favorable safety in castration-resistant prostate cancer patients with symptomatic bone metastases. Long-term radium-223 monitoring underlies a comprehensive safety and risk/benefit assessment.<h4>Objective</h4>To report updated ALSYMPCA safety, including long-term safety up to 3 yr after the first injection.<h4>Design, setting, and participants</h4>Safety analyses from phase 3 randomized ALSYMPCA trial included patients receiving ≥1 study-drug injection (600 radium-223 and 301 placebo). Patients (405 radium-223 and 167 placebo) entered long-term safety follow-up starting 12 wk after the last study-drug injection, to 3 yr from the first injection. Forty-eight of 405 (12%) radium-223 and 12/167 (7%) placebo patients completed follow-up, with evaluations every 2 mo for 6 mo, then every 4 mo until 3 yr.<h4>Outcome measurements and statistical analysis</h4>All adverse events (AEs) were collected until 12 wk after the last injection; subsequently, only treatment-related AEs were collected. Additional long-term safety was assessed by development of acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), aplastic anemia, and secondary malignancies. Data analysis used descriptive statistics.<h4>Results and limitations</h4>During treatment to 12 wk following the last injection, 564/600 (94%) radium-223 and 292/301 (97%) placebo patients had treatment-emergent AEs (TEAEs). Myelosuppression incidence was low. Grade 3/4 hematologic TEAEs in radium-223 and placebo groups were anemia (13% vs 13%), neutropenia (2% vs 1%), and thrombocytopenia (7% vs 2%). Ninety-eight of 600 (16%) radium-223 and 68/301 (23%) placebo patients experienced grade 5 TEAEs. Long-term follow-up showed no AML, MDS, or new primary bone cancer; secondary non-treatment-related malignancies occurred in four radium-223 and three placebo patients. One radium-223 patient had aplastic anemia 16 mo after the last injection. No other cases were observed. Limitations include short (3-yr) follow-up.<h4>Conclusions</h4>Final long-term safety ALSYMPCA analysis shows that radium-223 remained well tolerated, with low myelosuppression incidence and no new safety concerns.<h4>Patient summary</h4>Updated Alpharadin in Symptomatic Prostate Cancer (ALSYMPCA) trial findings show that radium-223 remained well tolerated during treatment and up to 3 yr after each patient's first injection.
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Prostate and Bladder Cancer Research
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European urology, 2018, 73 (3), pp. 427 - 435