Inclusion Criteria:

1. Males age ≥ 18 years with histologically confirmed adenocarcinoma of the prostate, which is now metastatic (e.g. any T, any N, M1a-c) based on bone scan, CT scan, or MRI scan.

2. Progression of disease despite androgen deprivation (androgen ablation or surgical castration) and anti-androgen withdrawal as documented by one or more of the following.

   • Progression of measurable disease per RECIST
   • Bone scan progression, defined as the appearance of ≥ 2 new lesions on bone scan, attributable to prostate cancer

   • Rising PSA, as defined by increasing levels on at least two consecutive assessments, following a prior assessment taken as a reference value, where all of the following are met:

     • The assessments are at least one week apart, with the first assessment at least one week later than the reference value
     • Progressive increase in the two assessments after the reference value, without an intervening decrease between assessments.
     • The last value prior to study entry is ≥ 2 ng/mL
3. Serum testosterone level ≤ 50 ng/dL post orchiectomy or while maintained on continuous or intermittent medical androgen suppression with a LHRH agonist or antagonist.
4. At least 2 weeks since ketoconazole or systemic steroids (any dose); 2 weeks since prior flutamide, megestrol, or aminoglutethimide; and at least 2 weeks since prior bicalutamide or nilutamide
5. Radiation therapy and/or therapy with samarium must have been completed 4 weeks prior to first dose of therapy. Strontium therapy must have been completed at least 12 weeks prior to the first dose of therapy. The patient must have recovered from all treatment-related toxicities.
6. ECOG performance status ≤ 2
7. Able to swallow and retain oral medication

Exclusion Criteria:

1. Received prior chemotherapy (including estramustine phosphate [Estracyt]) for HRPC. Adjuvant chemotherapy (including docetaxel) is allowed provided that progression of disease occurred ≥ 6 months after the completion of adjuvant therapy.
2. Patients must not be receiving concurrent anti-androgen hormonal therapy for HRPC (LHRH directed therapies are acceptable to maintain castrate levels of testosterone).
3. Treatment with monoclonal antibody (e.g., VEGF targeting antibody) or prostate cancer vaccine within 45 days prior to the first dose of study treatment. Acute toxicities from prior therapy must have resolved to Grade ≤ 1.
4. Known history of or clinical evidence of central nervous system (CNS) metastases or leptomeningeal carcinomatosis
5. Active secondary malignancy or history of other malignancy within the last 5 years
6. Prior history of radiation therapy to ≥ 30% of the bone marrow
7. Peripheral neuropathy of ≥ Grade 2
8. Patients with malabsorption syndrome, disease significantly affecting gastrointestinal function, or resection of the stomach or small bowel are excluded. Subjects with ulcerative colitis, inflammatory bowel disease, or partial or complete small bowel obstruction are also excluded.
9. Class 3 or 4 cardiac disease as defined by the New York Heart Association Functional Classification
10. Known active symptomatic fungal, bacterial and/or viral infection including active HIV. Note: screening for viruses is not required.
11. Psychiatric illness/social situations that would limit compliance with the study requirements.