Drug targeting with monoclonal antibodies. A review

Monoclonal antibodies have been widely used in attempts to target anti-neoplastic agents selectively to tumours. Problems associated with the use of monoclonal antibodies as the targeting moiety include lack of complete tumour selectivity, antigenic heterogeneity, tumour access and immunogenicity. Considerable effort in the targeting field is being expended in an attempt to reduce or overcome these problems. Attachment of monoclonal antibodies to low molecular weight cytotoxic drugs, protein toxins, radionuclides or enzymes capable of conversion of inactive prodrugs to cytotoxic drugs, has, despite these problems, resulted in conjugates which do have selective anti-tumour effects in animal models. The advantages and limitations of these different approaches are reviewed. It remains to be established in man if any of these approaches will result in significant therapeutic benefit in major solid tumours.