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