11.2.2 Gene Therapy Strategies for Cancer

Traditional cancer treatment is either radiation or chemotherapy.  These treatments depend on the action of these agents on destroying the rapidly dividing cells or by preventing cells from entering cell cycle and therefore stopping the cells from dividing. Recently, attention was made to use modern technology for cancer treatment. Among these technologies is gene therapy.  (Vile, 1996 and Roth & Cristiano 1997) that specifically targets cancer cells.

For gene therapy of cancer to be successful, the gene must target specifically the malignant cells, while leaving the normal tissue. This means the development of selective gene delivery with highly specific gene expression and specific gene product activity and possibly specific drug activation.

There are a number of approaches to gene therapy of cancer. These include, non-specific immune stimulation, selective enhancement of toxicity to cancer cells, general tumour suppressions and specific tumour suppression genes.

However, there are two principal obstacles that limit the advances in gene therapy of cancer. The first, is the development of the appropriate delivery system that must be reliable, safe and effective to introduce the genetic material into the target cells or tissues.  The second problem is the understanding of the molecular basis of cancer, in order to determine where single changes might allow effective anticancer therapy.

Progress is underway to develop a number of vectors used for gene delivery.  Viral vectors, such as retrovirus, adenovirus, adenoassociated virus are used (Robbins, et al 1998, Reynolds, et al 1999). Also non-viral methods such as using liposomes for injection are also used (Lasic,. 1998).   

The following represent some of the approaches used for gene therapy of cancer.