Abstract
Although the idea of immunotherapy for cancer is not new, recent advances in gene delivery systems and the discovery of new immunomodulatory genes has meant that the field is currently extremely active [1]. The delivery of genes which can modify the host’s response to its own tumour cells has been carried out both by using viral vectors and by non-viral delivery systems. In addition the genes have been delivered both directly to the tumours in vivo [2], or, more commonly, to tumour cells ex vivo, which are then re-injected into the tumour-bearing host [3]. There are two key features which may bear on the success of such approaches to the immunotherapy of cancer. Firstly the choice of immunomodulatory gene. Although there are a very large number of possible genes to test, and even larger number of potential combinations of genes, most reported work has concentrated on one or two key genes, principally cytokines such as IL-2 and GM-CSF. The second key element of the approach, and the subject of this article, is the choice of delivery system.