Microarray gene expression study of the RESPECT trial for the identification of prognostic and predictive markers.

e14561 Background: The RESPECT trial (n = 198) tested the addition of Sorafenib to standard mFOLFOX6 treatment in first line metastatic colorectal cancer (mCRC) patients but resulted in no statistical significant improvement in progression free survival, and no evidence for overall benefit. Sorafenib inhibits several Raf kinases (including B-Raf). Samples with high BRAF-mutant-like score were previously shown to identify a subset of colon tumors with a similar biology and outcome to BRAF mutant patients (Popovici et al. J. Clin. Oncol., 30(12):1288–95, 2012). Methods: A subset of 125 patients from the trial was available for gene expression analysis from their primary tumor FFPE samples, using the Colon DSA gene expression arrays from Almac. Mutation status for KRAS and BRAF was previously assessed. The potential prognostic and/or predictive effect of a high BRAF-mutant-like score was assessed. The analyses were performed using Cox proportional hazards regression models and Kaplan-Meier curves. The logran...