Cetuximab is a chimeric immunoglobulin G1 monoclonal antibody that targets the ligand-binding domain of the epidermal growth factor receptor and inhibits downstream intracellular signals.Research has shown that cetuximab can stimulate the autoimmune system and produce antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity reactions,which can recruit cytotoxic lymphocytes to attack and kill cancer cells.Cetuximab is mainly indicated for patients with epidermal growth factor receptor-positive metastatic colorectal cancer who fail to respond to both irinotecan- and oxaliplatin-based regimens.The efficacy and safety of cetuximab as monotherapy or in combination with other treatment options were evaluated in a series of phase Ⅱ and phase Ⅲ trials.Identifying the clinical and molecular markers that can predict which patient groups may best benefit from cetuximab treatment is key to improving patient outcomes and avoiding unnecessary toxicities and costs.Herein,we discuss the mechanisms of action by which cetuximab exerts its antitumor effects,as well as the possible clinical and molecular markers that may help predict therapeutic benefits for patients with metastatic colorectal cancer.