An investigational agent called abiraterone acetate significantly improves overall survival among men with advanced metastatic prostate cancer, according to new study findings presented at the 35th Annual European Society for Medical Oncology Congress.

Treatment with the drug was associated with a 35% reduction in death risk and a 36% increase in median survival compared with placebo (14.8 vs. 10.9 months).

In addition, the median time to PSA progression was 10.2 months for subjects who received abiraterone versus 6.6 months for placebo recipients, which translated into a significant 42% reduced risk of PSA progression, researchers reported.

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The phase 3 study involved 1,195 men with advanced metastatic castration-resistant prostate cancer previously treated with one or two chemotherapy regimens, at least one of which contained docetaxel. Researchers randomly assigned subjects receive abiraterone plus low-dose prednisone/prednisolone or prednisone/prednisolone plus placebo.

The abiraterone-treated patients experienced more mineralocorticoid-related adverse events than subjects in the placebo arm. The most frequent adverse events were fluid retention (30.5% vs. 22.3%) and hypokalemia (17.1% vs. 8.4%). Investigators observed liver function test abnormalities in 10.4% of the abiraterone group compared with 8.1% of the placebo recipients.

In a press release issued by abiraterone’s developer, Ortho Biotech Oncology Research & Development, one of the investigators, Johann S. de Bono, MD, PhD, of the Institute of Cancer Research, The Royal Marsden NHS Foundation, London, noted: “Abiraterone acetate has the potential to meet a significant unmet need so this news will be incredibly important to prostate cancer patients and their families.”

Another investigator, Howard I. Scher, MD, of Memorial Sloan-Kettering Cancer Center in New York, observed: “These results are important because men with progressive metastatic, castration-resistant prostate cancer often have a poor prognosis and currently have few treatment options.”

Ortho Biotech said it plans to file applications seeking market approval in the United States and Europe by the end of this year.