Tumor-specific gene therapy for pancreatic cancer using human neural stem cells encoding carboxylesterase

Advanced pancreatic cancer is one of the most lethal malignant human diseases lacking effective treatment. Its extremely low survival rate necessitates development of novel therapeutic approach. Human neural stem cells (NSCs) are known to have tumor-tropic effect. We genetically engineered them to express rabbit carboxyl esterase (F3.CE), which activates prodrug CPT-11(irinotecan) into potent metabolite SN-38. We found significant inhibition of the growth of BxPC3 human pancreatic cancer cell line in vitro by F3.CE in presence of CPT-11. Apoptosis was also markedly increased in BxPC3 cells treated with F3.CE and CPT-11. The ligand VEGF and receptor VEGF-1(Flt1) were identified to be the relevant tumor-tropic chemoattractant. We confirmed in vivo that in mice injected with BxPC3 on their skin, there was significant reduction of tumor size in those treated with both F3.CE and BxPC3 adjacent to the cancer mass. Administration of F3.CE in conjunction with CPT-11 could be a new possibility as an effective treatment regimen for patients suffering from advanced pancreatic cancer.