Blood-Based Biomarkers In Metastatic Colorectal Cancer Patients Treated With Folfiri Plus Regorafenib Or Placebo: Results From Lccc1029

587Background: The LCCC1029 trial demonstrated that addition of the multitargeted kinase inhibitor regorafenib (Rego) to FOLFIRI in metastatic colorectal cancer (mCRC) patients (pts) modestly prolonged progression-free survival (PFS). In this preplanned analysis, circulating angiogenic and inflammatory proteins were explored as potential prognostic and predictive biomarkers of Rego benefit. Methods: Plasma samples from 149 mCRC pts (107 in Rego + FOLFIRI and 42 in placebo + FOLFIRI) were evaluated for 20 markers at baseline (n = 149) and cycle 1 day 21 (C1D21, n = 81). Predictive and prognostic values of each marker at baseline were analyzed for both PFS and overall survival (OS) using Cox proportional hazard models. On-treatment changes were quantified as fold change [log2(C1D21/baseline)] and differences between arms were evaluated using the Mann-Whitney test. Results: The primary objective of this study was to determine whether any marker was predictive of benefit with Rego for PFS. Although no treatme...