Inclusion Criteria:

• Patient has hormone-refractory prostate cancer (HRPC) as evidenced by PSA progression or progression of measurable disease.
• Patient has greater than 25% increase in 2 consecutive tests in which the first increase in PSA should occur a minimum of 1 week apart.
• Patients on androgen deprivation treatment and will continue on androgen deprivation treatment during study participation except for patients who are post orchiectomy.
• Patient has evidence of metastatic disease by positive bone scan or evidence of progressive metastatic disease by CT scan.
• Patient has been treated with at least 1 prior hormone therapy or is post orchiectomy.
• Patient has been previously treated at a minimum for an 8-week treatment period on a docetaxel-based regimen for metastatic HRPC.
• Patient has PSA at least 5 ng/mL or greater.
• Patient has testosterone less than 50 ng/dL.
• Patient ECOG performance status of 0 or 1.
• Patient has life expectancy of greater than 8 weeks.
• Patient meets lab values: A. Absolute neutrophil count at least 1,500/mm^3 or greater; B.Platelet count at least 100,000/mm^3 or greater; C. Serum creatinine at least 1.5 mg/dL or less or creatinine clearance at least 60 mL/min or greater; D. Bilirubin less than 2.0 mg/dL. E. AST and ALT less or equal to 2.5 times upper limit of normal
• Any chemotherapy, major surgery, or irradiation must be completed at least 4 weeks prior to study drug.
• Patient recovered from clinically significant toxicities from prior treatment.

Exclusion Criteria:

• Prior treatment with 2 or more prior chemotherapy regimens.
• Concurrent treatment with an estrogen-containing agent including diethylstilbestrol (DES).
• Prior flutamide (Eulexin) within past 4 weeks, prior bicalutamide (Casodex) within past 6 weeks, or prior nilutamide (Nilandron) within past 6 weeks.
• Prior strontium or samarium or other radioisotope therapy.
• Prior radiation therapy to greater than 25% of the bone marrow (e.g., no whole pelvic irradiation is allowed).
• Uncontrolled congestive heart failure or angina, patients with a history of myocardial infarction within 2 months of enrollment.
• Patients with uncontrolled hypertension.
• Pre-existing cardiac, pulmonary, neurologic or other disease that would preclude study participation.
• Documented untreated central nervous system (CNS) metastases. However, patients with treated CNS metastases that have been stable are eligible.
• Any significant concurrent disease or illness, or psychiatric disorders or alcohol or chemical abuse that would preclude study participation.
• Active secondary malignancy except non-melanoma skin cancers.
• Known, active infection, or known HIV positive or presence of an AIDS related illness.