Molecularly targeted therapy for metastatic colon cancer: Proven treatments and promising new agents

There has been a dramatic upsurge in the investigation of molecularly targeted therapy in colorectal cancer over the past two decades, with the first success being bevacizumab, a monoclonal antibody directed at vascular endothelial growth factor (VEGF). The latest additions to our armament are epidermal growth factor receptor (EGFR) inhibitors and the discovery of K-ras mutation's impact on treatment efficacy. This review summarizes the new therapies targeting established pathways, such as VEGF and EGFR, and introduces tyrosine kinase inhibitors and monoclonal antibodies, as well as exciting novel agents targeting insulin-like growth factor, tumor necrosis factor, the Sonic Hedgehog pathway, Src kinase, mammalian target of rapamycin, and protein kinase C, which already have shown activity in other cancers and are currently being studied in phase 1/2 trials in metastatic colorectal cancer.