These enzymes convert harmless prodrugs into lethal drugs. Kill only tumor cells since that's the only area with the enyzme. C.Cancer Vaccines 1.Whole cancer cell vaccines - use either regular tumor cells or tumor cells that are engineered to express IL2 or IL4 cytokines. Induces immunity against both the virus and the tumor cells. 4.DNA vaccines - inject naked DNA into muscle tissue.
Normal cells take up DNA and begin expressing the protein which induces an immune response.