Inclusion Criteria:

          1. Written informed consent obtained prior to any study-related procedure being
             performed.

          2. Male patients at least 18 years of age or older at time of consent.

          3. Histological evidence of adenocarcinoma of the prostate.

          4. Patients must have one of the following documented conditions:

               -  Metastatic castration sensitive prostate cancer (mCSPC);

               -  Castration sensitive prostate cancer (CSPC) with biochemical relapse (using the
                  Prostate Cancer Working Group 3 [PCWG3] definition of PSA progression) of
                  prostate cancer;

               -  Castration sensitive prostate cancer (CSPC) with oligometastatic prostate cancer
                  (e.g., Positron Emission Tomography (PET) positive);

               -  Metastatic castration resistant prostate cancer (mCRPC) (only allowed in Phase 1
                  at the discretion of the Investigator and after a dose cohort that demonstrates
                  adequate suppression of serum testosterone is determined.)

          5. Undergone orchiectomy or ongoing GnRH agonist or antagonist therapy for at least 1
             month prior to the Screening Visit, AND a serum testosterone level <50 ng/dL but >2
             ng/dL at screening.

        Exclusion Criteria:

          1. Metastatic castration resistant prostate cancer (mCRPC) patients more than minimally
             symptomatic or with a reported pain score on an 11-point (0 - 10) numeric rating scale
             of >3 over the previous 7 days.

          2. Known active central nervous system (CNS) metastases. Patients with CNS metastases
             that have been treated with surgery and/or radiation therapy, who are off
             pharmacologic doses of glucocorticoids, and who are neurologically stable are
             eligible.

          3. Clinically significant cardiac disease, defined as any of the following:

               -  Clinically significant cardiac arrhythmias including bradyarrhythmia and/or
                  subjects who require anti-arrhythmic therapy (excluding beta blockers or
                  digoxin). Subjects with controlled atrial fibrillation are not excluded.

               -  Congenital long QT syndrome

               -  QTcF ≥450 msec at Screening.

               -  History of clinically significant cardiac disease or congestive heart failure
                  >New York Heart Association Class II or left ventricular ejection fraction
                  measurement of <50% at baseline. Subjects must not have unstable angina (symptoms
                  at rest) or new-onset angina within the last 3 months or myocardial infarction
                  within the past 6 months.

               -  Uncontrolled hypertension, defined as systolic blood pressure >160 mmHg or
                  diastolic blood pressure >100 mmHg which has been confirmed by 2 successive
                  measurements despite optimal medical management.

               -  Arterial or venous thrombotic or embolic events such as cerebrovascular accident
                  (including transient ischemic attacks), deep vein thrombosis, or pulmonary
                  embolism within the 3 months before start of study medication (except for
                  adequately treated catheter-related venous thrombosis occurring >1 month before
                  the start of study medication).

          4. Prior treatment with abiraterone, orteronel or current treatment with systemic
             ketoconazole or any other CYP17 inhibitor.

          5. Required concomitant use of strong inducers of CYP3A4 and substrates of CYP2C8 and
             CYP2D6.