Analysis of plasma protein biomarkers from the phase 3 CONCUR study of regorafenib in Asian patients with metastatic colorectal cancer (mCRC).

672 Background: In the randomized phase 3 CONCUR trial (NCT01584830), regorafenib significantly improved overall survival (OS) and progression-free survival (PFS) vs placebo (PBO) in Asian patients (n = 136 regorafenib; n = 68 PBO) with treatment-refractory mCRC (HR [95% CI]: OS 0.55 [0.40‒0.77]; PFS 0.31 (0.22‒0.44]). Protein biomarker data from the phase 3 CORRECT trial of mostly Western patients with mCRC identified TIE-1 as a potential predictor of clinical response to regorafenib; however, this association was not significant in multivariable analyses. We present an exploratory protein biomarker analysis of patients in CONCUR. Methods: Sixteen proteins of interest, many of which are involved in angiogenesis, were quantified by multiplex immunoassay or ELISA in plasma samples collected at study entry from 121/204 (59%) patients (n = 83 regorafenib; n = 38 PBO). Potential predictive and prognostic effects were evaluated. Results: The biomarker cohort was representative of the overall study population i...