Cancer therapy is given by using two different gene systems.

GCG-HSVtk suicide gene therapy and gene based  immunotherapy have been combined to treat cancers. 

Tumor cells transduced separately with HSV tk gene and  cloned cytokine cDNA or gene.

Cytokines such as Interleukin-2, Interleukin-12, and others act as signals that mobilize immune cells and stimulate immune response against tumor cells.

Tumor cell peptides that are released, after cell death caused by suicide gene therapy, will interact with immune cells and cause immunological reaction against tumor cells.  An added benefit is circulating tumor cell antibodies which  prevent initiation of cancer at other sites in the body.