Evaluation of the Short and Intermediate Term Outcomes of Ablation of Locally Advanced Unresectable Pancreatic Cancer Using the NanoKnife Irreversible Electroporation (IRE) System - A Prospective Study

The prognosis for pancreatic cancer is dismal, with a five-year survival rate of 4.9%. Current treatment options include surgical resection, chemotherapy and radiation. Only 15% percent of pancreatic cancers are considered resectable at the time of diagnosis. Current chemotherapeutic options are limited, as pancreatic adenocarcinoma is poorly responsive to chemotherapy. Radiofrequency ablation of the pancreas in the setting of locally advanced unresectable disease has been described in a few case series1-6, but implementation of that technology is limited by concerns over thermal injury to adjacent organs and vessels. With 42,470 new cases of pancreatic cancer diagnosed annually in the US and given that pancreatic cancer is expected to claim 35,240 lives this year in the US7, it is the fourth leading cause of cancer death in the Unites States. This information supports the notion that there is an unquestionable need for novel therapeutic strategies for the treatment of this disease.

Irreversible electroporation (IRE) has the potential to dramatically widen the treatment options for patients with pancreatic cancer. It provides a minimally invasive procedure that could potentially avoid radical surgery for smaller lesions, and it could potentially offer palliation of symptoms such as pain, gastric outlet obstruction and jaundice in patients with locally advanced unresectable disease. Preliminary studies of IRE in the liver and prostate have demonstrated that structures such as bile ducts, ejaculatory ducts, neurovascular bundles, blood vessels, and the urethra heal normally after ablation, suggesting that vessels and ducts within and around the pancreas may also be heal normally. Collagen matrix during treatment with IRE is not destroyed thus allowing for a structure to heal normally. There is no evidence that nerve ganglion are damaged.

Heat based ablative therapy in the pancreas has the potential for unique complications. Pancreatic necrosis is believed to play a role in creating a potentially life-threatening systemic inflammatory response in patients with severe acute pancreatitis8, 9 and the presence of free active pancreatic enzymes is believed to contribute to the inflammatory cascade of acute pancreatitis. Irreversible electroporation could potentially cause both pancreatic necrosis and the release of active pancreatic enzymes. Additionally, the pancreas surrounds or abuts several vital structures, including the common bile duct, the pancreatic duct, the superior mesenteric artery and vein (SMA and SMV), the portal vein, the stomach, and the duodenum. IRE as a non-thermic ablative modality has the potential to achieve pancreatic ablation with respect of the surrounding vascular and ductal structures.

Electroporation is a technique that increases cell membrane permeability by momentarily changing the transmembrane potential and subsequently disrupting the lipid bi-layer integrity to allow transportation of molecules across the cell membrane via nano-size pores. This process - when used in a reversible fashion - has been used in research for drug or gene delivery into cells.

Irreversible electroporation (IRE) is a method to induce irreversible disruption of cell membrane integrity (loss of cell homeostasis) resulting in cell death without the need for additional pharmacological injury. Because IRE is a non-thermal technique, changes associated with perfusion-mediated tissue cooling (or heating) are not relevant. While cells in the ablation region are destroyed, the underlying extracellular matrix is not damaged thus allowing tissues in the ablation zone to heal normally.