Rationale: The introduction of angiogenesis inhibitors, like sunitinib and bevacizumab, has improved the outcome of patients with several types of cancer remarkably. However, their application is hampered by side effects, such as development of hypertension with consequences for renal and cardiac function. Moreover patients treated with angiogenesis inhibitors may suffer from weight loss, and insulin sensitivity during treatment appears to change. The treatment with angiogenesis inhibitors, will improve life expectancy of patients with various cancer diagnoses and therefore the clinical relevance of both short term and long lasting adverse events will translate into reduced quality of life. In addition, premature withdrawal of angiogenesis inhibitors due to side effects may result in lower response, shorter duration of response and possibly a shorter survival. Therefore, adequate treatment of above mentioned side effects in patients treated with angiogenesis inhibitors is of relevance for the response rate, the duration of progression free survival and overall survival and for quality of life.

Mechanistic insight in the pathogenesis of these side effects will help optimizing treatment.

Objective: The primary objective of the study is to investigate the effect of sunitinib on endothelial function, insulin sensitivity, renal function and renal blood flow.

Study design: Single-centre non randomized observational study Study population: 30 Patients (>18 years old) starting with sunitinib as treatment for metastatic renal cell carcinoma.

Inclusion Criteria:

• Subject is able and willing to sign the Informed Consent Form
• Age 18 years or older
• WHO performance status 0-2
• Life expectancy ≥ 12 weeks
• mRCC patients in which the treatment of choice is sunitinib

Exclusion Criteria:

• Use of corticosteroids
• Any evidence of severe or uncontrolled diseases other than renal cell carcinoma eg, unstable or uncompensated respiratory, cardiac, hepatic or renal disease.
• Known risk of the patient transmitting HIV, hepatitis B or C via infected blood
• Patients being treated with oral anticoagulants if to be included in group A.

30 patients with metastatic renal cell carcinoma starting treatment with sunitinib