A Prospective Observational Study for Assessment and Outcome Association of Circulating Endothelial Cells in Clear Cell Renal Cell Carcinoma Patients Who Show Initial Benefit from First-line Treatment. The CIRCLES (CIRCuLating Endothelial cellS) Study (SO

Antiangiogenics are the cornerstone of treatment in kidney cancer. Since they target endothelial rather than tumor cells, we studied the correlation between levels of circulating endothelial cells in peripheral blood and long-term benefit in patients on antiangiogenic therapy. Higher levels were associated with long-term benefit, suggesting that this determination could help to separate best responders from those who could require a more intensive approach.