Bayer HealthCare Pharmaceuticals has reported that the investigational drug radium-223 chloride showed positive data in the phase III ALSYMPCA (ALpharadin in SYMptomatic prostate cancer) trial. The study met its primary endpoint by significantly improving overall survival by 44% in patients with castration-resistant prostate cancer (CRPC) and symptomatic bone metastases. All of the main secondary efficacy endpoints analyzed to date were met, including delay in skeletal-related events (SREs).

The data showed that patients who were treated with radium-223 chloride had the following outcomes: median overall survival of 14 months compared to 11.2 months for the placebo group; time to first SREs (13.6 months vs. 8.4 months, 64% improvement); total alkaline phosphatase (ALP) normalization (33% vs. 1% of patients); and a 49% improvement in time to prostate-specific antigen (PSA) progression.

The most common non-hematologic adverse events (occurring in at least 15% of patients) included bone pain (43% vs. 58%), nausea (34% vs. 32%), diarrhea (22% vs. 13%), constipation (18% vs. 18%) and vomiting (17% vs. 13%); and the most common hematologic adverse events included anemia (27% vs. 27%) for patients receiving radium-223 chloride as compared to placebo. With respect to grade 3 to 4 adverse events, the most common events included bone pain (18% vs. 23%) for patients receiving radium-223 chloride as compared to placebo. Following a pre-planned interim analysis, the company agreed with the Independent Data Monitoring Committee's (IDMC) recommendation to stop the study and offer patients on the placebo arm treatment with radium-223 chloride.

Radium-223 chloride was recently granted Fast Track designation by the FDA. The company plans to file a New Drug Application with the FDA for radium-223 chloride in mid-2012.