Intermittent Androgen Deprivation Therapy for Stage IV Castration Sensitive Prostate Cancer

Prior treatment

• 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.
• Prior surgical castration
• 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.

Other illness

• Requiring opioids for cancer related pain.
• 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.

Other

• Documented central nervous system metastases or liver metastasis
• Delayed healing of wounds, ulcers, and/or bone fractures
• Inability to comply with protocol requirements

• 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