Orteronel/Prednisone Combo Improves Progression-Free Survival in Men With Metastatic Prostate Cancer
Improvement in overall survival not statistically significant
Data from a pivotal, international, double-blind, randomized, phase III clinical trial have shown that the investigational drug orteronel (Takeda Pharmaceutical Company) plus prednisone reduced the risk of radiographic progression-free survival (rPFS), one of the study’s two primary endpoints, by 30% compared with placebo plus prednisone in men with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) (median rPFS, 11.0 vs. 8.3 months, respectively; P < 0.001).
The study’s other primary endpoint, overall survival (OS), showed a numerical improvement in median OS of 1.9 months, which was not statistically significant compared with that of placebo (median OS, 31.4 vs. 29.5 months, respectively; P = 0.314).
Results from this study will be presented June 1 at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago.
The study compared orteronel 400 mg twice daily (BID) plus prednisone 5 mg BID with placebo plus prednisone in 1,560 men with progressive chemotherapy-naïve mCRPC (i.e., increasing prostate-specific antigen [PSA] levels and/or radiographic evidence of metastases) and serum testosterone levels of less than 50 ng/dL post-orchiectomy or with maintained gonadotropin-releasing hormone (GnRH) suppression.
In the study, men with progressive mCRPC were randomly assigned to either the treatment group or the control group. The final analysis for rPFS was conducted at an interim analysis for OS, and the final analysis for OS was conducted at 600 deaths.
Key secondary endpoints showed that more patients experienced at least a 50% decrease in PSA levels and favorable circulating tumor cell counts at 12 weeks in the treatment arm compared with the control arm.
Common adverse events with orteronel plus prednisone compared with control included nausea (36% vs. 15%, respectively), fatigue (34% vs. 20%), constipation (33% vs. 15%), and diarrhea (28% vs. 14%). Thirty percent and 18% of patients in the treatment and control arms, respectively, discontinued therapy because of adverse events.
Source: Takeda; May 16, 2014.