Development of molecular biomarkers in individualized treatment of colorectal cancer

Colorectal cancer is a leading cause of cancer mortality despite recent expansion of treatment options in metastatic colorectal cancer (mCRC). Our knowledge about key signaling pathways in colorectal tumors has contributed to the identification of specific molecular markers of response to targeted agents. In this review we discuss well-established and potential predictive biomarkers of benefit with epidermal growth factor receptor (EGFR) inhibitors. Data derived from multiple phase III trials have indicated that KRAS mutations can be considered a highly specific negative biomarker of response to anti-EGFR monoclonal antibodies. Other molecular aberrations in pathways downstream of EGFR such as BRAF, NRAS, and PIK3CA mutations, and PTEN loss are also reviewed. Moreover biomarkers of efficacy to classic chemotherapeutic agents as well as recent advances regarding high-throughput technologies and circulating tumor cells are also considered. Personalized cancer medicine in the mCRC scenario seems to be near reality, but validation of many biomarkers in prospective clinical trials is urgently warranted.