In this study, glycosaminoglycan (GAG) profiling in subjects first diagnosed with metastatic ccRCC is hypothesized to be useful in monitoring drug response and predict the outcome of a CT scan. To this end, regularly measured plasmatic and urinary GAGs in prospectively enrolled subjects will be correlated to drug response as evaluated by the designated clinician based on CT scans. A positive correlation indicates that this test can successfully detect patients that are not responding to treatment before the scheduled follow-up in which CT scans are performed. Data on the extent of metastasis (number of metastatic sites) will be collected to assess whether the biomarker level correlates accordingly.