The Developing Role of Anti-Epidermal Growth Factor Receptor Agents in the Treatment of Advanced or Metastatic Colorectal Cancer.

The first studies of epidermal growth factor receptor (EGFR) inhibitors in metastatic colorectal cancer were begun before the predictive role of RAS mutations had been elucidated. Secondary analyses of many large randomized trials have shown that mutations in exons 2-4 of KRAS and NRAS, BRAF V600E mutation, and right-sided primary tumor all predict lack of response to EGFR inhibition in the first-line setting. However, even in patient populations defined by a lack of these negative predictors, there is still not uniform response to anti-EGFR therapy. Additionally, although older adults have been shown to have the potential to both tolerate and respond to anti-EGFR therapy, the criteria for selecting the most appropriate older patients for treatment remain unclear.