The investigators wish to explore the variability of baseline metabolomic profile in the blood and urine of patients with mRCC and characterise the inter-subject and intra-subject variability. The study of the baseline levels has not been performed in this cohort previously. This is extremely important in interpreting the emerging data of changes in the levels of the various biomarkers from various trials. This will in turn help in the development of future targeted therapies, especially Phase I/II studies where an early demonstration of target modulation is vital. This study will also help to identify the number of patients required for appropriate statistical evaluation in pharmacodynamic studies to assess biological activity, optimisation of dosing, and investigation of potential mechanisms of resistance. Study of the urinary and blood metabolomic profile in conjunction will give us an insight into the potential use of urine as a diagnostic and prognostic tool.