Intermittent Androgen Deprivation Therapy for Stage IV Castration Sensitive Prostate Cancer

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