Feasibility of endoscopic ultrasound-guided OncoGel (ReGel/paclitaxel) injection into the pancreas in pigs

Background and Study Aims: OncoGel (ReGel/paclitaxel) is a formulation of the chemotherapeutic drug paclitaxel which can be injected intratumorally, and which was developed for local treatment of solid tumors. Immediately after injection, and in response to body temperature, an insoluble gel depot of OncoGel is formed inside the tissue. Paclitaxel is released continuously from this depot into the adjacent tissue for up to 6 weeks. The aim of this study was to determine the feasibility of injecting OncoGel into pig pancreas under endoscopic ultrasound (EUS) guidance. Methods: Three pigs were sedated by general anesthesia and OncoGel was injected under EUS guidance into the tail of the pancreas using a 22-gauge needle. The end points of this study were the feasibility of the injections, the presence of gross and/or microscopic evidence of inflammation in the pancreas after injection, and how well the animals tolerated the procedure. Results: EUS-guided fine-needle injection of 2 ml of OncoGel into the tail of the pancreas was performed successfully in all three animals. The injections took an average of 4 minutes and an echo-rich intrapancreatic focus was visible by EUS in the tail of the pancreas after injection. The animals were monitored for 4 days (n = 2)or 5 days (n = 1) after the injection and no fever(average body temperature was 37.8 C), vomiting,or anorexia was observed during this period. After the animals had been killed, a depot of OncoGel was observed in the tail of the pancreas, both grossly and histologically. There was no evidence of extravasation of OncoGel Out of the pancreas, and cross-sectional histological studies demonstrated the depot but no evidence of pancreatitis. There was an abrupt transition from the OncoGel depot to normal pancreatic tissue with no sclerotic or necrotic tissue formation. Conclusions: EUS-guided injection of OncoGel into the pancreas was successful in all the pigs and We found no evidence of pancreatitis. This technique is a potential option for minimally invasive local treatment of unresectable pancreatic cancer.