Soluble Tie2 and Flt1 extracellular domains in serum of patients with renal cancer and response to antiangiogenic therapy

Antiangiogenesis drugs can be difficult to evaluate because they produce di sease stabilization rather than tumor regression. Markers of endothelial ma ss in tumors may be of value to monitor therapy and evaluate such drugs, So luble domains of the endothelial receptor tyrosine kinases, sTie2 (angiopoi etin receptor) and sFlt1 (vascular endothelial growth factor receptor-1) we re analyzed by sandwich ELISA in serum samples from 43 patients with advanc ed renal cancer before and 1 month after antiangiogenic therapy with razoxa ne, Pretreatment sFlt1 levels were 0.77 ng/ml +/- 0.48 (SD) and sTie2 74.3 ng/ml +/- 15 (SD), Pretreatment sFlt1 levels above the median were associat ed with a lesser chance of stable disease (P = 0.04) and poorer survival (P = 0.01), Fall of sTie2 on treatment was associated with stable disease (P = 0.05) and improved survival (P = 0.04), The soluble receptors measured we eks before response were assessed and correlated with response and survival , showing they may be useful to monitor and develop antiangiogenic therapy.