Gene Therapy of Cancer

Abstract

Gene therapy is defined as the transfer of defined genetic material to specific target cells of a patient for the ultimate purpose of preventing or altering a particular disease state (Jain 1998). It has three components: (1) identification of the gene that is mutated in a disease and obtaining a healthy copy of that gene, (2) carrier or delivery vehicle called vectors to deliver the healthy gene to a patient’s cells, and (3) additional DNA elements that turn on the healthy gene in the right cells and at the right levels. Gene therapy usually involves in situ production of therapeutic proteins but some approaches require suppression of gene expression to achieve therapeutic effects. Applications of gene therapy would be narrow if confined only to transfer of defined genetic material to specific target cells using vectors, which are usually viral but several nonviral vectors are used as well. Genes and DNA can be introduced without the use of vectors, and various techniques are being used to modify the function of genes in vivo without gene transfer, e.g., gene repair. Gene medicines may modify the effects of genes. If one includes cell therapy, particularly with the use of genetically modified cells, the scope of gene therapy becomes much broader. As a further extension, one can include genetically modified bacteria for delivery of therapeutic agents. Gene therapy can now be combined with antisense techniques and RNA interference (RNAi), further increasing the therapeutic scope. Details of gene therapy techniques are described in detail in a special report on this topic (Jain 2013). Cancer, the most important application of gene therapy currently, is the topic of this chapter.