The purpose of this study is to determine the proportion of patients with a serological prostate specific antigen (PSA) by day 85.

A serological PSA response is defined as a reduction from baseline PSA serum concentration of at least 50%, which is confirmed by a second PSA value 28 or more days later.

Inclusion Criteria:

• at least 18 yrs of age
• diagnosis of adenocarcinoma of the prostate
• no detectable metastatic disease as assessed by bone and CT scans
• has increasing serum PSA concentrations
• life expectancy of at least 3 months
• ECOG of 0 or 1
• has been withdrawn from antiandrogen therapy for at least 6 weeks prior to entering screening period

Exclusion Criteria:

• has asymptomatic disease
• has active GI ulceration or bleeding
• has been treated with non-hormonal systemic anticancer therapy or has received radiation within 4 weeks of baseline visit
• bilirubin >2x ULN or ALT or AST >2xULN or serum creatinine >1.5mg/dL
• hemoglobin <9g/dL or platelets below 100,000/uL or ANC below 1500/uL
• receiving treatment for HIV with protease inhibitors
• has had prior malignancy within past 5 yrs with exception of resected basal or squamous cell carcinomas of the skin
• has used investigational drug with previous one month