Strategy for the modification of cells with cytokines is intensively developing cancer gene therapy . Numerous studies have shown that one of the most effective therapeutic approach is to introduce the gene for interleukin-12 (IL -12) produced in the tumor microenvironment . This prevents severe toxicities caused by IL- 12 administered systemically . The most numerous research papers concern the cancer cells modified to secrete IL -12 ex vivo and used as a vaccine . It was also demonstrated high efficacy fibroblasts introduced gene for IL -12. Due to the modification of dendritic cells to secrete IL -12 were also able to enhance the effectiveness of the related therapeutic strategies. Progress in the field of genetic engineering has allowed the introduction of genes for IL-12 in vivo by gene transfer with adenovirus , and the herpes virus or pox . Non-viral gene transfer methods for IL -12 include the direct injection of naked DNA into skeletal muscles , skin or tumor tissue . Effectiveness of gene transfer was by electroporation or using the ' bombardment ' DNA. Taken up trial with IL -12 gene specifying the mouth. The effectiveness of cancer therapy with IL -12 gene has been enhanced by the simultaneous administration of cytokines : IL- 2 , -15 , -18 , GM- CSF , TNF- ? , Chemokine IP-10 and MIG welding , the introduction of genes for costimulatory molecules B7.1 and 4 - 1BB and adoptive therapy . Experiments in animal models have demonstrated the therapeutic efficacy of modified cells to secrete IL -12. This made it possible to take the first clinical trials.