Background: TRIBE is a phase III randomized trial comparing FOLFOXIRI/ Bev vs FOLFIRI/Bev as first-line treatment for metastatic colorectal cancer. In this post genomic area, whole exome sequence is emerging as an useful tool to identify novel snps to associated with clinical outcome. Here we tested the hypothesis that whole exome sequence may identifies snps to predict clinical outcome in mCRC patients enrolled in TRIBE study. Methods: Genomic DNA was extracted from peripheral blood of 503 pts. Arm A(FOLFIRI/BEV)(n=253); Arm B (FOLFOXIRI/BEV)(n=250), median age 60 years(29-75), Females(n=202) and males(n=301);Median follow up is 32.3 months. The Illumina HumanExome array with custom content was genotyped on 432 pts on Illumina HiSeq plateform. After applying genotyping quality control filters, 385 individuals and 241,812 single nucleotide polymorphisms (SNPs) remained in the analysis. Arm A included 163 pts with a mean age of 59.9 years (SD=9.14) and mean OS of 22.9 months while Arm B included 222 pts with mean age of 59.9 years and mean OS of 23.3 months. A Cox proportional hazard regression analysis was implemented to assess SNP associations with RR,PFS and OS after adjusting for sex, treatment arm, age at trial entry, number of metastases, ECOG, and mutation status for KRAS and BRAF. GenABEL was used for the statistical analysis. Results: Although our main effect analysis did not identify a genome-wide association (P<5x10^-8), our preliminary analysis did observe several promising associations between SNPs and OS. Our top association, rs10008360 on chromosome 4(VEGFR-2), with hazard ratio (HR) of 6.49 (P=2.84x10^-6). We observed four additional markers associated with OS (P<1.0x10^-4). Rare burden testing and pathway analyses are underway to determine additional biological candidates. Updated detailed analysis including response and PFS results will be presented at meeting. Conclusions: This is the first study identifies novel snps may predict which patient could benefit from bevacizumab-based therapy. These preliminary data warrants further validation clinical trials.