Inclusion Criteria:

• Diagnosed with radiographically-documented metastatic prostate cancer that has progressed while receiving androgen-suppressive therapy in the form of a bilateral orchiectomy or GnRH agonist (eg, leuprolide, goserelin).
• Patients must demonstrate evidence of progressive disease based on 1 of the following criteria: 1) Progressive measurable disease, or 2) Progressive rise in PSA level (2 consecutive rises from a prior reference level), or 3) Development of new lesions on bone scan.
• If receiving a GnRH agonist as primary hormonal therapy, the serum testosterone level must be ≤ 50 ng/mL.
• Must have received and progressed during or following 1 prior chemotherapy regimen for metastatic disease (not including an anti-androgen or ketoconazole); or, must have discontinued prior systemic therapy because of poor tolerance or other adverse effects; or, must have refused chemotherapy treatment. Patients having undergone more than 1 prior chemotherapy regimen may be admitted at the discretion of the sponsor.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2.
• Baseline serum PSA level of ≥ 10 ng/mL

Exclusion Criteria:

• Received any anti-cancer medications in the 30 days before receiving their first dose of study medication except for GnRH agonists and bisphosphonates.
• Any unresolved toxicity greater than or equal to Grade 2 from previous anti-cancer therapy, except for stable chronic toxicities not expected to resolve, such as peripheral neurotoxicity.