Inclusion Criteria

• Must meet all of the following
  • Voluntary written consent
  • Male
  • Age 18 years or older
  • Histologically or cytologically confirmed diagnosis of prostate adenocarcinoma
  • Radiograph-documented metastatic disease
  • Progressive disease
  • Prior surgical castration or concurrent use of an agent for medical castration
  • Either absence of pain or pain not requiring use of any opioid or narcotic analgesia in the 2 weeks prior to study entry
  • Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
  • Even if surgically sterilized, must practice effective barrier contraception during the entire study treatment and for 4 months after the last dose of study drug, or abstain from heterosexual intercourse
  • Meets screening laboratory values as specified in protocol
  • Stable medical condition

Exclusion Criteria

• Must not meet any of the following
  • Known hypersensitivity to orteronel, prednisone or gonadotropin-releasing hormone (GnRH) analogue
  • Received prior therapy with orteronel, aminoglutethimide, ketoconazole or abiraterone
  • Received antiandrogen therapy within 6 weeks for bicalutamide and 4 weeks for all others prior to first dose of study drug
  • Continuous daily use of oral prednisone or oral dexamethasone for more than 14 days within 3 months prior to study
  • Received prior chemotherapy for prostate cancer with exception of neoadjuvant/adjuvant therapy as part of initial primary treatment for local disease that was completed 2 or more years prior to screening
  • Exposure to radioisotope therapy within 4 weeks of receiving first dose of study drug
  • Exposure to external beam radiation within 2 weeks of start of screening until receiving the first dose of study drug
  • Documented central nervous system metastases
  • Treatment with any investigational compound within 30 days prior to first dose of study drug
  • Current spinal cord compression, bilateral hydronephrosis or current bladder neck outlet obstruction
  • Diagnosis or treatment of another malignancy within 2 years preceding first dose of study drug except nonmelanoma skin cancer or in situ malignancy completely resected
  • Uncontrolled cardiovascular condition as specified in study protocol
  • Known history of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis C
  • Unwilling or unable to comply with protocol
  • Uncontrolled nausea, vomiting or diarrhea
  • Known gastrointestinal disease or procedure that could interfere with oral absorption or tolerance of orteronel