Inclusion Criteria:

- Histologically or cytologically confirmed adenocarcinoma of the prostate, but not
with neuroendocrine differentiation or of small cell histology

- Prior chemotherapy for prostate cancer with regimen(s) containing paclitaxel or
docetaxel

- Documented prostate-specific antigen (PSA) progression according to PSA Working Group
eligibility criteria with a PSA >5 ng/mL

- On-going androgen deprivation with serum testosterone <50 ng/dL (< 2.0nM)

- Serum potassium >=3.5 mmol/L

- Eastern Cooperative Oncology Group (ECOG) Performance Status of <=2 (Karnofsky
Performance Status >=50%)

- No history of adrenal insufficiency or hyperaldosteronism

- Any acute toxicities of prior chemotherapy, radiotherapy have resolved to a NCI CTCAE
(version 3) grade of <=1 (chemotherapy induced alopecia and grade-2 neuropathy are
excluded from this consideration)

- No radiotherapy, chemotherapy, or immunotherapy within 30 days of administration of
the Cycle 1 Day 1 (supportive care with glucocorticoid is not considered as an
immunotherapy; however, PSA progression must be documented under current
dose/regimen)

- No surgery or local prostatic intervention within 28 days of the first dose and any
clinically relevant sequelae from the surgery must have resolved prior to Cycle 1 Day
1)

- Agrees to protocol-defined use of effective contraception

- Life expectancy >12 weeks

Exclusion Criteria:

- Active or uncontrolled autoimmune disease that may require corticosteroid therapy

- Serious or uncontrolled co-existent non-malignant disease, including active and
uncontrolled infection

- Uncontrolled hypertension

- Laboratory values not within protocol-defined parameters

- Clinically significant heart disease as evidenced by a myocardial infarction in the
past 12 months, severe or unstable angina, or New York Heart Association (NYHA) Class
III or IV heart disease (patients with a history of atherosclerotic vascular disease
requiring coronary or peripheral artery bypass surgery may be enrolled provided the
surgery occurred at least 2 years prior to enrollment and after consultation with a
cardiologist to insure that the disease is stable)

- Other malignancy within the previous 5 years other than basal cell or squamous cell
carcinomas of skin with a >30% probability of recurrence within 12 months

- History of gastrointestinal disorders (medical disorders or extensive surgery) which
may interfere with the absorption of the study medication

- Current enrollment in an investigational drug or device study or participation in
such a study within 30 days of Cycle 1 Day 1

- Condition or situation which, in the investigator's opinion, may put the patient at
significant risk, may confound the study results, or may interfere significantly with
patient's participation in the study