Potential predictive and prognostic biomarkers identified in baseline plasma samples from the VELOUR trial.

638 Background: Biomarkers of resistance or susceptibility to vascular endothelial growth factor (VEGF) inhibition have not been validated. Ziv-aflibercept (ZALTRAP), a fusion protein that binds and neutralizes ligands of VEGFR1 and VEGFR2 (e.g., VEGFA, PLGF, and VEGFB), is approved for the treatment of metastatic colorectal cancer (mCRC) in combination with FOLFIRI in patients who have progressed after oxaliplatin therapy. We are currently analyzing plasma samples from VELOUR, the registration trial of FOLFIRI +/- ziv-aflibercept, in an effort to identify prognostic and predictive factors. Methods: VELOUR was a prospective, multicenter, multinational, randomized (1:1), double-blind, parallel-arm phase III study conducted in 1,226 patients. Retrospective analysis of circulating proteins from 553 baseline plasma samples was performed. Samples were analyzed for levels of 98 analytes using multiplex assays and ELISA. Biomarker values were dichotomized around the median value and analyzed with respect to over...