Targeted therapies in colorectal cancer: Complications and management

The promise of targeted therapeutics is tumor selectivity. The gold standard for this approach is monoclonal antibodies with exquisite target specificity. In the case of colorectal cancer, this promise has been partially fulfilled. The epidermal growth factor and vascular endothelial growth factor pathways were identified as putative therapeutic targets and inhibitory antibodies were developed with clinical activity. However, although these reagents are not associated with toxicities characteristic of traditional cytotoxics, they are not devoid of side effects. In fact, these side effects can generally be explained on the basis of expected biologic effects of the reagents, highlighting the notion that targets with true tumor specificity remain elusive. In this review, we will profile the unique toxicities associated with monoclonal antibody inhibitors of the epidermal growth factor receptor and vascular endothelial growth factor, and offer suggestions for management.