Monoclonal antibodies (MAbs) are a relatively new innovation in cancer treatment.At present,some monoclonal antibodies have increased the efficacy of the treatment of certain tumors with acceptable safety profiles.When monoclonal antibodies enter the body and attach to cancer cells,they function in several different ways:first,they can trigger the immune system to attack and kill that cancer cell; second,they can block the growth signals; third,they can prevent the formation of new blood vessels.Some naked MAbs such as rituximab can be directed to attach to the surface of cancer cells and make them easier for the immune system to find and destroy.The ability to produce antibodies with limited immunogenicity has led to the production and testing of a host of agents,several of which have demonstrated clinically important antitumor activity and have received U.S.Food & Drug Administration (FDA) approval as cancer treatments.To reduce the immunogenicity of murine antibodies,murine molecules are engineered to remove the immunogenic content and to increase their immunologic efficiency.Radiolabeled antibodies composed of antibodies conjugated to radionuclides show efficacy in non-Hodgkins lymphoma.Antivascular endothelial growth factor (VEGF) antibodies such as bevacizumab intercept the VEGF signal of tumors,thereby stopping them from connecting with their targets and blocking tumor growth.Trifunctional antibodies have revealed a new perspective in cancer therapy extending beyond primary destruction of tumor cells.