We investigated potential biomarkers of efficacy in a phase III trial of sunitinib versus interferon-alpha ( IFN - ) , first-line in metastatic renal cell carcinoma ( mRCC ) , by analyzing plasma levels of vascular endothelial growth factor ( VEGF ) - A , VEGF-C , soluble VEGF receptor-@ ( sVEGFR-@ ) and interleukin ( IL ) -@ .