Gene-based cancer immunotherapy and vaccines

Extract: Cancer cells are able to escape immune detection and/or rejection by a variety of measures. Cell surface molecules, which are required for the effective policing of tissues by the immune system, are often modified, reduced or eliminated. In addition cancer cells secrete soluble molecules that inhibit the patients' ability to develop an immune response. The ability of the immune system to recognize and reject cancerous growths has been demonstrated in a series of experimental model systems. Efforts are now being made to use this knowledge for the treatment of cancer. Described below are two different gene-based approaches to stimulate the rejection of an established cancer in patients. The first involves procedures which modify the tumor itself, render it a more attractive target to the immune system, and allow immune cells to penetrate the tumor and kill the cancerous cells. The second approach requires a very powerful vaccine to stimulate a strong immune response against the tumor associated antigens in patients with an established cancer. Early efforts to harness the power of the immune system to eliminate cancer were made by Dr. William Coley very early in the 20th century. Dr. Coley injected cancerous tissue, usually sarcomas (tumors of the supportive tissues such as bone, cartilage fat or muscle), with a mix of bacteria and/or their toxins. This would result in an inflammatory response in the tumor and the influx of many immune cells.