Inclusion Criteria:

          -  Histologically or cytologically confirmed adenocarcinoma of the prostate.

          -  >75% prostate specific antigen (PSA) decline after 12 to 16 weeks of run in period
             with Gonadotropin-releasing Hormone (GnRH) analog abiraterone plus prednisone.

          -  Performance status Eastern Cooperative Oncology Group (ECOG) 0-1

          -  Adequate organ function Serum alanine aminotransferase (ALT) or aspartate
             aminotransferase (AST) must be < 2.5 x upper limit of normal (ULN), total bilirubin
             less than 1.5 X ULN, estimated creatinine clearance must be >40 mL/min, absolute
             neutrophil count (ANC) > 1500/l, hemoglobin above 9 g/dl, platelet count > 100,000/l

          -  Stable medical condition, including the absence of acute exacerbations of chronic
             illnesses, serious infections or major surgery within 28 days prior to study
             enrollment

          -  Ability to give written informed consent

        Exclusion Criteria:

          -  Prior GnRH analog with GnRH analogue for non-metastatic prostate cancer within 12
             months prior to study enrollment or >3 months of GnRH analog in the metastatic setting

          -  Prior treatments with TAK-700/Orteronel, ketoconazole, apalutamide or enzalutamide.

          -  Documented central nervous system metastases or liver metastasis

          -  Prior surgical castration

          -  Requiring opioids for cancer related pain.

          -  Treatment with any investigational compound within 30 days prior to the first dose of
             study drugs

          -  Diagnosis or treatment for another systemic malignancy within 2 years before the first
             dose of study drugs, or previously diagnosed with another malignancy & have any
             evidence of residual disease. Patients with non-melanoma skin cancer or carcinoma in
             situ of any type are not excluded if they have undergone complete resection.

          -  Uncontrolled hypertension despite appropriate medical therapy (blood pressure of
             greater than 160 mmHg systolic and 90 mmHg diastolic at 2 separate measurements no
             more than 60 minutes apart during the Screening period). Note: Patients may be
             rescreened after adjustments of antihypertensive medications

          -  Unstable symptomatic ischemic heart disease, ongoing arrhythmias of Grade > 2 (NCI
             CTCAE, version 5), New York Association Class III or IV heart failure

          -  Known human immunodeficiency virus (HIV) infection, active chronic hepatitis B or C
             not contained with anti-viral therapy, life threatening illness unrelated to cancer,
             or any serious medical or psychiatric illness that could, in investigator's opinion,
             potentially interfere with participation in this study.

          -  Known gastrointestinal (GI) disease or GI procedure that could interfere with the GI
             absorption or tolerance of study drugs, including difficulty swallowing tables.

          -  Delayed healing of wounds, ulcers, and/or bone fractures

          -  Inability to comply with protocol requirements