Temsirolimus is a drug that is being studied to possibly treat kidney cancer. It works by starving the cancer of nutrients, by cutting off the blood supply, which is hoping to shrink the cancer. This study will look at the experimental use of temsirolimus, 12 weeks prior to the surgical removal of the entire kidney or a portion of the kidney that is involved by the tumor.

This study will also find out whether or not there are certain biological factors that show up in patients during their treatment with this drug. This will be able to predict how their disease will respond to the therapy (biomarkers), and this will possibly allow anti-cancer therapies to be developed in the future to tailor to a patient's needs.

Inclusion Criteria:

• At least 18 years old and capable of giving informed consent.
• Patient has radiological evidence of RCC consisting of: CT scan with stage T2, T3, T3a, T4, or any stage T with N1/2 and/or metastatic disease.
• Patient is already having a nephrectomy.
• Adequate cardiac function as assessed by electrocardiogram (ECG).
• Patient is will to have a kidney biopsy at baseline/screening.
• Patient has scored a 0 or 1 on the ECOG.
• Patient is negative for HIV, Hepatitis B, Hepatitis C
• If patient is a woman of child-bearing potential, they have to have a negative pregnancy test.

Exclusion Criteria:

• Patient has stage T1 disease without metastases.
• Patient has abnormal laboratory values at screening within the following ranges:
• Absolute neutrophil count ≤1.5 x 10(9)/L; Platelet count ≤ 100 x 10(9)/L
• Leukocyte count ≤ 3 x 10(9)/L; Hemoglobin ≤ 80 g/L
• Serum creatinine ≥ 2.0 x the upper normal limit (UNL)
• Total bilirubin ≤ 1.5 x UNL; AST and ALT ≤ 3.0 x UNL
• Fasting serum cholesterol ≤ 9.0 mmol/L
• Fasting serum triglycerides ≤ 5.0 mmol/L
• Patients with a known hyper-sensitivity to Temsirolimus.
• Other currently active malignancies.
• Currently taking any medications known to interfere with the metabolism of Temsirolimus.
• Patients receiving anticoagulation with warfarin.
• Patients with a history of pulmonary hypertension or interstitial lung disease.
• Unstable angina as judged by the primary investigator, or any recent MI in the last 180 days.