All subjects may receive up to six cycles of treatment consisting of two treatment days, Days 1 and 8, in a 28-day cycle. Patients will receive intra-tumoral injection of pIL-12 at a concentration of 0.5mg/ml and a fixed volume of 0.25 mL per each 1.0 cm diameter of target region, followed immediately by electrical discharge around the tumor site resulting in electroporation of plasmid DNA into tumor cells.