Reovirus inhibits the peritoneal dissemination of pancreatic cancer cells in an immunocompetent animal model.

The prognosis of pancreatic cancer with peritoneal dissemination has not improved. The aim of this study was to clarify whether oncolytic reovirus is effective against the peritoneal dissemination of pancreatic cancer in an immunocompetent animal model. The hamster pancreatic cancer cells HaP-T1 were inoculated into the peritoneal cavity of the hamster and reovirus (1x10(8) plaque-forming units) was administered into the peritoneal cavity on days 1, 3, 5 and 7 after HaP-T1 inoculations. The number and weight of the disseminated nodules in each group were recorded. Reovirus protein in the disseminated nodules was examined by immunohistochemical staining. The tumor volumes of peritoneal dissemination in the treatment group were significantly less than those in the control group (p<0.05). In addition, the amount of ascites was decreased in the treatment group in comparison to the control group. Immunohistochemical examination revealed that reovirus replication was seen only in the disseminated nodules but not in surrounding normal tissues. There were no serious side effects observed in this study. These data suggested that intraperitoneal administration of reovirus might be an effective form of oncolytic viral therapy for peritoneal dissemination of pancreatic cancer.