Enzalutamide, a potent oral androgen receptor inhibitor, improves survival in men with metastatic castration-resistant prostate cancer (CRPC) before and after chemotherapy. Bicalutamide, a nonsteroidal antiandrogen, is widely used to treat men with nonmetastatic or metastatic CRPC.
The efficacy and safety of these drugs were compared in this randomized, double-blind, phase II study of men with CRPC.
A total of 396 men with nonmetastatic (n = 139) or metastatic (n = 257) CRPC were randomly assigned to enzalutamide 160 mg per day (n = 198) or bicalutamide 50 mg per day (n = 198). Androgen deprivation therapy was continued in both arms. The primary end point was progression-free survival (PFS).
Enzalutamide reduced the risk of progression or death by 76% compared with bicalutamide (hazard ratio [HR], 0. 24; 95% CI, 0. 18 to 0. 32; P < . 001). Median PFS was 19. 4 months with enzalutamide versus 5. 7 months with bicalutamide. Enzalutamide resulted in significant improvements in all key secondary end points: time to prostate-specific antigen progression (HR, 0. 19; 95% CI, 0. 14 to 0. 26; P < . 001); proportion of patients with a ≥ 50% prostate-specific antigen response (81% v 31%; P < . 001); and radiographic PFS in metastatic patients (HR, 0. 32; 95% CI, 0. 21 to 0. 50; P < . 001). Beneficial effects with enzalutamide were observed in both nonmetastatic and metastatic subgroups. The observed adverse event profile was consistent with that from phase III enzalutamide trials.
Enzalutamide significantly reduced risk of prostate cancer progression or death compared with bicalutamide in patients with nonmetastatic or metastatic CRPC.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2016 Jan 25 [Epub ahead of print]
Supported by Medivation and Astellas Pharma Global Development (codevelopers of enzalutamide) for the STRIVE study and for Ellen Lewis, PhD, Timothy Lohret, PhD, and Shannon Davis of Infusion Communications who provided writing and editorial assistance. Presented in part at the American Urological Association 2015 Annual Meeting, New Orleans, LA, May 15-19, 2015.
David F Penson, Andrew J Armstrong, Raoul Concepcion, Neeraj Agarwal, Carl Olsson, Lawrence Karsh, Curtis Dunshee, Fong Wang, Kenneth Wu, Andrew Krivoshik, De Phung, Celestia S Higano
David F. Penson, Vanderbilt University Medical Center and Tennessee Valley Veterans Administration Medical Center Geriatric Research, Education, and Clinical Center; Raoul Concepcion, Urology Associates PC, Nashville, TN; Andrew J. Armstrong, Duke Cancer Institute, Duke University, Durham, NC; Neeraj Agarwal, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT; Carl Olsson, Icahn School of Medicine at Mount Sinai, New York, NY; Lawrence Karsh, The Urology Center of Colorado, Denver, CO; Curtis Dunshee, Urological Associates of Southern Arizona, Tucson, AZ; Fong Wang and Kenneth Wu, Medivation, San Francisco, CA; Andrew Krivoshik, Astellas Pharma Global Development, Northbrook, IL; De Phung, Astellas Pharma Global Development, Leiden, The Netherlands; and Celestia S. Higano, Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA.