Vaccines and Monoclonal Antibodies

The immunoglobulin molecule contains structural features that make it a powerful tool for cancer therapy (eg, an extremely high specificity and binding affinity for the target molecule that results in low toxicity). Several approaches have been used: monoclonal antibodies targeting a ligand (eg, bevacizumab, anti-vascular endothelial growth factor), monoclonal antibodies targeting a receptor (eg, cetuximab, anti-epidermal growth factor receptor), vaccines targeting a ligand (eg, G17DT, anti-gastrin), or a cell surface antigen (eg, carcinoembryonic antigen-TRIad of COstimulatory Molecules, anti-CEA). Another approach attempts to harness the cellular arm of the immune response (ie, cytotoxic T cells, natural killer cells) for specific killing of tumor cells. The putative underlying mechanism of antibody strategy is the inhibition of intracellular signaling pathways and induction of apoptosis. Clinical evidence suggests that while most of these antibodies achieve limited antitumor activity as monotherapy, they are significantly more efficacious than single agents when combined with chemotherapy. Future use of these agents will include optimized combination chemotherapy/immunotherapy regimens as well as monoclonal antibodies conjugated to cytotoxic molecules and radionuclides.