Enzalutamide versus abiraterone as a first-line endocrine therapy for castration-resistant prostate cancer (ENABLE study for PCa): a study protocol for a multicenter randomized phase III trial

Both enzalutamide and abiraterone have demonstrated improved radiographic progression-free and overall survival for castration-resistant prostate cancer (CRPC) compared with placebo controls before docetaxel treatment in phase III studies. These oral agents target androgen and androgen receptor signaling and are thought to be less toxic than chemotherapy. Cross-resistance to these agents was recently reported because of their similar mechanism of action, and it is important to assess which agent is more effective to use initially for CRPC.

The present study is a phase III, investigator-initiated, multicenter, head-to-head, randomized controlled trial investigating enzalutamide vs. abiraterone as a first-line treatment for CRPC patients. Patients will be randomly assigned to an enzalutamide or an abiraterone treatment group. The primary endpoint is the time to prostate-specific antigen progression. The target sample size is set at 100 patients per group (total, 200 patients). The study duration is 5 years, and the duration for recruitment is 2 years and 6 months.

Thus far, there have been no prospective head-to-head studies comparing enzalutamide and abiraterone. This ENABLE study will clarify which agent should be prioritized for CRPC patients and enable clinicians to decide the appropriate treatment before chemotherapy.

University hospital Medical Information Network (UMIN) Center identifier UMIN000015529 . Registrated 11/1/2014.

BMC cancer. 2017 Oct 10*** epublish ***

Kouji Izumi, Atsushi Mizokami, Mikio Namiki, Shogo Inoue, Nobumichi Tanaka, Yuko Yoshio, Kei Ishibashi, Manabu Kamiyama, Noriyasu Kawai, Hideki Enokida, Takashi Shima, Shizuko Takahara

Department of Integrative Cancer Therapy and Urology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan. ., Department of Integrative Cancer Therapy and Urology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8641, Japan., Department of Urology, Institute of Biomedical and Health Science, Hiroshima University, Hiroshima, Japan., Department of Urology, Nara Medical University, Nara, Japan., Nephro-Urologic Surgery and Andrology, Division of Reparative and Regenerative Medicine, Institute of Medical Life Science, Mie University Graduate School of Medicine, Tsu, Japan., Department of Urology, Fukushima Medical University, Fukushima, Japan., Department of Urology, University of Yamanashi, Chuo, Japan., Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan., Department of Urology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan., Department of Urology, Toyama Prefectural Central Hospital, Toyama, Japan., Innovative Clinical Research Center, Kanazawa University, Kanazawa, Japan.