Preliminary results from two trials presented at the 44th Annual Meeting of ASCO in Chicago have consolidated the role of K-ras as a biomarker of nonresponse to cetuximab and panitumumab in metastatic colorectal cancer (mCRC). The phase III CRYSTAL and OPUS trials presented unplanned subgroup analyses of the correlation of K-ras status with response to therapy with first-line FOLFIRI or FOLFOX, respectively, with or without cetuximab in patients with mCRC. Both studies demonstrated a clear benefit with the addition of cetuximab in K-ras WT patients.
