Electroporation Gene Therapy Preclinical and Clinical Trials for Melanoma

In vivo electroporation (EP) is a versatile delivery method for gene transfer which can be applied to any accessible tissue. Delivery of plasmid DNA encoding therapeutic genes or cDNAs with in vivo EP has been tested extensively in preclinical melanoma models. Direct delivery to the tumor has been shown to generate a direct antitumor effect. Delivery to alternative sites may generate additional therapeutic options, for example the production of cancer vaccines, the reduction of tumor angiogenesis, or the induction of tumor cell apoptosis. Several of the preclinical therapies tested have a demonstrated therapeutic effect against melanomas. Two immunotherapies have advanced to melanoma clinical trials. Delivery of a plasmid DNA encoding interleukin-12 (IL-12) or interleukin-2 (IL-2) using electroporation was demonstrated to be safe with no grade 3 or 4 toxicities reported. Delivery of IL-12 with electroporation resulted in significant necrosis of melanoma cells in the majority of treated tumors and significant lymphocytic infiltrate in biopsies from patients in several cohorts. In addition, clinical evidence of responses in untreated lesions suggested the induction of a systemic response following therapy. This review discusses preclinically tested electroporation gene therapies for melanoma with clinical potential and the conversion of these therapies to clinical trials.