Challenges in monoclonal antibody-based therapies.

Therapeutic monoclonal antibodies (mAbs) are the fastest growing class of new therapeutic molecules. They hold great promises for the treatment of a variety of diseases, including chronic inflammatory diseases and cancer. However, the current manufacturing and purification processes cause limitations in the production capacity of therapeutic antibodies, leading to an increase in cost. Genetic delivery of therapeutic monoclonal antibodies by in vivo production offers a new potential solution to these problems. Firstly, therapeutic efficacy can be improved by maintaining stable therapeutic, non-toxic levels within the blood circulation over a long period of time. Repeated high-dose bolus injections could be avoided, thereby reducing the possibility of side-effects. Secondly, the high cost of manufacturing and purification of the therapeutic antibodies could be reduced, making an in vivo/ex vivo mAb gene transfer an economically viable and attractive option. In general, three approaches can be used for the stable long-term expression and secretion of therapeutic antibodies in vivo: 1) direct in vivo administration of integrating vectors carrying a mAb gene, 2) grafting of ex vivo genetically modified autologous cells, and 3) implantation of an encapsulated antibody producing heterologous or autologous cells. This paper describes the key factors and problems associated with the current antibody-based immunotherapies and reviews prospects for genetic in vivo delivery of therapeutic antibodies.