These phenomena inspired the development of numerous rudimentary cancer immunotherapies, starting with nonspecific immunostimulatory approaches first used by William Coley [1] and leading to the concept of therapeutic vaccination against cancer. The recent identification and characterization of genes coding for tumour antigens (Ag) has enabled the design of antigen-specific cancer vaccines based on plasmid DNA and recombinant viral vectors. Gene therapy can be used to manipulate the immune system to help body's natural defences to recognise and target cancer cells.