ORLANDO, Fla., Feb. 12, 2013 /PRNewswire/ -- Janssen Research & Development, LLC [Janssen] announced today updated results showing ZYTIGA ® (abiraterone acetate) plus prednisone continued to provide statistically significant improvements in disease progression compared to placebo plus prednisone, and longer overall survival in men with metastatic castration-resistant prostate cancer. The Phase 3, randomized, multicenter, placebo-controlled study (COU-AA-302) also demonstrated statistically significant improvement compared to placebo in the secondary endpoints of median time to opiate use for prostate cancer pain and to initiation of chemotherapy. The data, from the latest pre-specified interim analysis of the study, were presented today at the annual American Society of Clinical Oncology Genitourinary Cancers Symposium (ASCO GU). "These results show that the benefits of earlier use of abiraterone acetate are sustained for many patients with metastatic castration-resistant prostate cancer," said Dana Rathkopf, MD, lead investigator of the study and assistant attending physician in the Genitourinary Oncology Service at Memorial Sloan-Kettering Cancer Center in New York City. "We were particularly pleased with the long median overall survival among patients treated with abiraterone acetate plus prednisone." Results from this most recent analysis and earlier interim analyses from COU-AA-302 were the basis of the December 2012 U.S. Food and Drug Administration (FDA) approval of an expanded indication for ZYTIGA, in combination with prednisone, for the treatment of patients with mCRPC. The European Commission has also approved an expanded indication for ZYTIGA for the treatment of patients with mCRPC. "It's important that clinicians have proven treatments to offer patients with metastatic castration-resistant prostate cancer before chemotherapy," said Michael L. Meyers, M.D., Ph.D., vice president, compound development team leader, ZYTIGA, Janssen. "When ZYTIGA was first approved, it provided a significant option for men with metastatic castration resistant disease after chemotherapy with docetaxel; now, with its broader indication and supported by the data presented at ASCO GU, we are pleased that more mCRPC patients may benefit from this treatment option. The findings also broaden our knowledge about the therapeutic activity of ZYTIGA." The analysis showed a statistically significant 47 percent reduction in risk of disease progression – measured as radiographic progression-free survival (rPFS) – in the ZYTIGA plus prednisone arm (ZYTIGA arm) compared to the placebo plus prednisone arm (control arm). The median rPFS was 16.5 months in the ZYTIGA arm vs. 8.3 months in the control arm [hazard ratio (HR) 0.53; 95% confidence interval (CI): 0.45 to 0.62; P<0.0001].