[Progress of gene therapy for esophageal cancer in Japan]

Retrovirally expressed interleukin-2 gene, granulocyte macrophage-colony stimulating factor gene, herpes simplex virus-thymidine kinase gene and p53 gene in human esophageal cancer cells showed antitumor effects in a nude mice xenotransplant model. We established a clinical protocol of gene therapy for advanced esophageal cancer using the wild type p53 gene with an adenovirus vector. In December of 2000, we began the first tumor suppressor gene therapy trial. Now, this trial, which has 9 patients. There have been no serious adverse event excluding fever and local pain. The feasibility of this treatment appears fairly good in these 9 cases. Furthermore, we developed a new method for transducing genes without a virus vector since a virus vector has several potentially unwanted properties. In vivo electroporation is a useful strategy for cancer gene therapy. Moreover, electric pulse to established solid tumors increases intracellular concentrations of chemotherapeutic agents. Transduction of the wild-type p53 gene by electroporation decreased the amount of nedaplatin required for tumor suppression. Electrochemo-gene therapy is a relatively simple method and can produce a better therapeutic effect.