Enzalutamide significantly reduced the risk of prostate cancer progression or death compared with bicalutamide in patients with nonmetastatic or metastatic castration-resistant prostate cancer (CRPC), a study published online ahead of print in the Journal of Clinical Oncology has shown.1
Bicalutamide is a nonsteroidal antiandrogen that is widely used to treat men with nonmetastatic or metastatic CRPC. Enzalutamide, a potent oral androgen receptor inhibitor, improves survival in patients with metastatic CRPC before and after chemotherapy. Therefore, investigators sought to compare the efficacy and safety of these drugs in men with nonmetastatic or metastatic CRPC.
For the double-blind, phase 2 trial, researchers enrolled 396 men with CRPC and randomly assigned them to receive androgen deprivation therapy with either enzalutamide 160 mg daily or bicalutamide 50 mg daily.
Results showed that enzalutamide significantly reduced the risk of progression or death by 76% compared with bicalutamide (HR, 0.24; 95% CI: 0.18-0.32; P<.001). Researchers found that median progression-free survival was 19.4 months with enzalutamide vs 5.7 months with bicalutamide.
Enzalutamide was also associated with a significant improvement in time to prostate-specific antigen (PSA) progression (HR, 0.19; 95% CI: 0.14-0.26; P<.001), a PSA response of 50% or greater (P<.001), and radiographic progression-free survival in patients with metastatic disease (HR, 0.32; 95% CI: 0.21-0.50; P<.001).
Furthermore, researchers observed beneficial effects with enzalutamide in both patients with nonmetastatic and metastatic disease.
In terms of safety, the reported safety profile was consistent with that of phase 3 enzalutamide trials.
1. Penson DF, Armstrong AJ, Concepcion R, et al. Enzalutamide versus bicalutamide in castration-resistant prostate cancer: The STRIVE trial [published online ahead of print January 25, 2016]. J Clin Oncol. doi:10.1200/JCO.2015.64.9285.