Safety and Efficacy Study of Enzalutamide Plus Leuprolide in Patients With Nonmetastatic Prostate Cancer (EMBARK)

The purpose of this study is to assess enzalutamide plus leuprolide in patients with high-risk nonmetastatic prostate cancer progressing after radical prostatectomy or radiotherapy or both. The randomized / blinded portion of the study is now completed following primary endpoint analyses. The study remains ongoing in open label format.

Inclusion Criteria: * Histologically or cytologically confirmed adenocarcinoma of the prostate at initial biopsy, without neuroendocrine differentiation, signet cell, or small cell features; * Prostate cancer initially treated by radical prostatectomy or radiotherapy (including brachytherapy) or both, with curative intent; * PSA doubling time ≤ 9 months; * Screening PSA by the central laboratory ≥ 1 ng/mL for patients who had radical prostatectomy (with or without radiotherapy) as primary treatment for prostate cancer and at least 2 ng/mL above the nadir for patients who had radiotherapy only as primary treatment for prostate cancer; * Serum testosterone ≥ 150 ng/dL (5.2 nmol/L). Exclusion Criteria: * Prior or present evidence of distant metastatic disease as assessed by radiographic imaging; * Prior hormonal therapy. Neoadjuvant/adjuvant therapy to treat prostate cancer ≤ 36 months in duration and ≥ 9 months before randomization, or a single dose or a short course (≤ 6 months) of hormonal therapy given for rising PSA ≥ 9 months before randomization is allowed.; * Prior cytotoxic chemotherapy, aminoglutethimide, ketoconazole, abiraterone acetate, or enzalutamide for prostate cancer; * Prior systemic biologic therapy, including immunotherapy, for prostate cancer; * Major surgery within 4 weeks before randomization; * Treatment with 5-α reductase inhibitors (finasteride, dutasteride) within 4 weeks of randomization; * Known or suspected brain metastasis or active leptomeningeal disease; * History of another invasive cancer within 3 years before screening, with the exception of fully treated cancers with a remote probability of recurrence