Monoclonal Antibodies as Immune Modulators for Cancer Therapy

Monoclonal antibodies may modulate immune and/or biological responsesalone, or as carriers of specific agents. Monoclonal antibodies directed against tumours may be indirectlycytotoxic by modulation of antibody-dependent, cell-mediated cytotoxicity or complement-mediatedcytotoxicity. Monoclonal antibodies directed against certain tumour cell receptors may alter the biologicalbehaviour of tumour cells such as blocking or downregulation of growth factors essential to tumour cellproliferation. Monoclonal antibodies directed to certain receptors on host immune cells. such as the CD3receptor on T lymphocytes. may activate those cells and increase their cytotoxicity. Antitumour monoclonalantibodies can serve as carriers of interferons, interleukin-2, tumour necrosis factor and other lymphokinesand cytokines to modulate selectively the cytotoxic potential of immune cells in the vicinity of tumour cells.Cytotoxic chemotherapy agents conjugated to antitumour monoclonal antibodies may be processeddifferently so that they bypass certain mechanisms of drug resistance. The penultimate application ofmonoclonal antibodies in cancer therapy is to combine various monoclonal antibodies and immunoconjugatesfor selective combination therapy based on known antigenic tumour cell determinants and thestatus of the host immune system