Inclusion Criteria:

- Histologically confirmed carcinoma of the prostate. Histologic evidence may be
confirmed through local or metastatic biopsy review

- Radiographic Evidence of metastatic disease

- Evidence of disease progression despite castrate levels of testosterone.

- A circulating timor cell count using FDA approved CellSearch methodology of ≥ 10 per
7.5 cc whole blood, drawn within 4 weeks of study registration

- Serum PSA greater than or equal to 2ng/dl at registration

- At least 4 weeks since prior palliative radiation therapy and/or major surgery, and
resolution of all toxic effects of prior therapy NCI CTCAE Grade less than or equal
to 1

- Age ≥ 18 years

- Adequate laboratory parameters

- Karnofsy Performance Status ≥ 60

- Life expectancy of at least 3 months

Exclusion Criteria:

- History of or active central nervous system metastases

- The use of cytotoxic, biologic, or hormonal therapies within 4 weeks of study entry.

- Subjects receiving known strong CYP3A4 isoenzyme inhibitors and/or inducers

- Major surgery, open biopsy, traumatic injury, or radiotherapy within 4 weeks of the
screening visit

- Have not recovered from prior biopsy, surgery, traumatic injury, and/or radiation
therapy.

- Presence of non-healing wound or ucer

- Grade ≥ 3 hemorrhage in the past month to study entry

- Hypertension with systolic blood pressure of ≥ 180mmHg and/or diastolic pressure ≥
100mmHg (Anti-hypertensive medications are permitted)

- Subjects with Class 2-4 heart disease or any history of congestive heart failure with
an ejection fraction <50% or a recent (within 12 months) cardiovascular event.

- Anticoagulation with warfarin

- Diabetes mellitus with glycosylated hemoglobin A1c ≥ 10% despite therapy

- History of interstitial pneumonitis

- Subjects with active autoimmune disorder(s) being treated with immunosuppressive
agents within 4 weeks prior to screening visit

- Subjects receiving immunosuppressive agents and those with chronic
viral/bacterial/fungal illnesses. Replacement doses of corticosteroids are
permitted.

- Active infection(s), active antimicrobial therapy or serious intercurrent illness.

- History of other prior malignancy in past 5 years, other than basal cell carcinoma,
squamous cell carcinoma of the skin, cervical carcinoma in sity, localized prostate
cancer, or superficial bladder cancer.

- Agreement to use medically acceptable contraceptive methods while on study and for 3
months after the last dose of temsirolimus.

- Any other major medical or psychiatric illness that, in the investigator's judgment,
will substantially increase the risk associated with the subject's participation in
this study, including inability to absorb oral medications.

- Known hypersensitivity to any of the components in the temsirolimus infusion or other
medical reasons for not being able to receive adequate premedication.

- QTc interval on baseline EKG of >500 milliseconds

- the use of agents that significantly prolong the QTc interval and who are unable to
stop medications prior to study initiation.

- Prior exposure to an mTOR inhibitor

- Presence of nephrotic syndrome as determined by clinical evaluation of 24 hour urine.