According to a new study published in the Journal of Clinical Oncology, researchers have found that the addition of orteronel to prednisone did not improve overall survival in patients with metastatic castration-resistant prostate cancer that progressed following treatment with docetaxel.
Orteronel is an investigational, nonsteroidal, reversible, selective 17,20-lyase inhibitor. For the double-blind, multicenter phase 3 study, researchers enrolled 1,099 men with advanced castration-resistant prostate cancer who have progressed during or after docetaxel-based therapy and randomly assigned them to received prednisone 5mg twice daily in combination with orteronel 400mg or placebo.
Results showed that the median overall survival was 17.0 months and 15.2 months for the orteronel-prednisone and placebo-prednisone groups, respectively (HR = 0.886; 95% CI: 0.739 - 1.062; P = 0.190). Despite no improvement in overall survival, researchers found orteronel-prednisone improved radiographic progression-free survival (median, 8.3 vs 5.7 months; HR = 0.760; 95% CI: 0.653 - 0.885; P < 0.001).
In addition, orteronel-prednisone decreased PSA ≥50% in 25% of patients compared with 10% of the placebo-prednisone patients. In regard to safety, nausea, vomiting, fatigue, and increased amylase were more frequently observed in the orteronel-prednisone group than the placebo-orteronel group.
Although there was no significant improvement in overall survival, the findings suggest that orteronel-prednisone has antitumor activity.
This study examined orteronel in patients with metastatic castration-resistant prostate cancer that progressed after docetaxel therapy. The study did not meet the primary end point of OS. Longer rPFS and a higher PSA50 rate with orteronel-prednisone indicate antitumor activity.