Treatment with ZYTIGA plus prednisone also resulted in an estimated 21 percent reduction in risk of death [HR=0.79; 95% CI: 0.66, 0.96, P=0.0151]. The median overall survival (OS) in the ZYTIGA arm was 35.3 months and was 30.1 months in the control arm. At the time of this interim analysis, conducted when approximately 55 percent of overall survival events (deaths) occurred, the pre-specified p-value for statistical significance was not met.Secondary Endpoints Treatment with ZYTIGA plus prednisone also resulted in significant improvements in all secondary study endpoints compared to the control arm, specifically:
- 39 percent decrease in the risk of initiation of cytotoxic chemotherapy for prostate cancer: a median of 26.5 months for the ZYTIGA arm vs. 16.8 months for the control arm [HR=0.61 (95% CI: 0.51, 0.72); P<0.0001].
- 29 percent decrease in the risk of opiate use for cancer pain: the median time for the ZYTIGA arm was not reached and was 23.7 months for the control arm [HR=0.71; 95% CI: (0.59, 0.85); P<0.0002].