Inclusion Criteria:

          -  Male 18 years of age or older.

          -  Histologically, pathologically, or cytologically confirmed prostate cancer without
             small cell features.

          -  Evidence of castration-resistant prostate cancer (CRPC).

          -  Presence of metastatic disease at study entry documented by 1 or more bone lesions on
             bone scan or by soft tissue disease observed by CT/MRI.

          -  No further treatment options available known to confer clinical benefit in this
             disease setting from the perspective of the treating physician.

          -  Evidence of progressive disease defined as 1 or more Prostate Cancer Working Group 3
             (PCWG3) criteria.

          -  The patient must have recovered from toxicities related to any prior treatments.

          -  Castrate at screening.

          -  Patients receiving bisphosphonates or other approved bone-targeting therapy must be on
             a stable dose for at least 4 weeks prior to the start of study drug.

          -  Demonstrate adequate organ function.

          -  Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 1.

        Exclusion Criteria:

          -  Biologic anti-cancer therapy or a cytotoxic chemotherapy within 4 weeks prior to the
             start of study drug.

          -  Use of hormonal agents with anti-tumor activity against prostate cancer within 4 weeks
             prior to the start of study drug.

          -  Intervention with any chemotherapy, investigational agents, or other anti-cancer drugs
             within 14 days or 5 half-lives, whichever is longer, of the first dose of study drug.

          -  Use of radium-223 dichloride or other radioligand/radiopharmaceutical within 28 days
             prior to the start of study drug.

          -  Received limited-field palliative bone radiotherapy >5 fractions and/or any
             radiotherapy within 2 weeks prior to the start of study drug.

          -  Received a blood transfusion within 28 days of screening.

          -  Known intra-cerebral disease or brain metastasis unless adequately treated and stable
             for the last 4 weeks before enrollment.

          -  Spinal cord compression.

          -  Diagnosis of another invasive malignancy within the previous 3 years other than
             curatively treated non-melanomatous skin cancer or superficial urothelial carcinoma.

          -  Gastrointestinal disorder affecting absorption.

          -  Significant cardiovascular disease.

          -  Concurrent disease or any clinically significant abnormality.

          -  Use of compounds known to be strong inducers and strong inhibitors of CYP3A and CYP2C8
             within 14 days of the first dose of study drug.

          -  Use of narrow therapeutic index sensitive CYP2C8 or sensitive substrates for CYP3A and
             CYP2B6.