(CHICAGO, IL) – Radium-223 chloride therapy significantly prolongs median overall survival (OS) time for men with castration-resistant prostate cancer (CRPC) bone metastasis, according to a randomized, double-blind, multinational Phase 3 trial presented at the 2012 American Society of Clinical Oncology Annual Meeting.

“Radium-223, a first-in-class alpha emitter, may provide a new standard of care for the treatment of CRPC patients with bone metastasis,” said lead author Chris Parker, MD, Consultant Clinical Oncologist at the Royal Marsden NHS Foundation Trust, Sutton, UK. 

Eligible patients had confirmed symptomatic CRPC with 2 or more bone metastases, no known visceral metastasis, and were not currently taking docetaxel. Patients were randomized 2:1 to receive 6 intravenous administrations of Ra-223 (50kBq/kg) every 4 weeks (n=614) or matching placebo (n=307).

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Compared to placebo, radium-223 significantly prolonged median OS by 3.6 months (14.9 vs. 11.3 months; HR=0.695; P=0.00007) and was associated with a 30.5% reduction in the risk of death. Radium-223 also significantly prolonged median time to first skeletal related event (SRE) by 5.5 months (HR=0.64; P<0.0001), Dr. Parker and colleagues reported.

Grade 3/4 toxicities were similar between the radium-223 and placebo arms (neutropenia, 2% vs. 1%; thrombocytopenia, 6% vs. 2%). Grade 3/4 anemia occurred in 13% of patients in each study arm.

“Further follow-up in all randomized patients continues to show highly favorable safety profile,” Dr. Parker said. “Safety and tolerability of Ra-223 remained favorable, with low myelosuppression.”