Exosomes from pancreatic cancer-associated fibroblasts and mesenchymal stem cells that have been transduced with the yeast cytosine deaminase::uracil phosphoribosyl transferase release suicide gene exosomes acting as "Trojan horse" drugs, effectively killing pancreatic cancer cells by converting the non-toxic prodrug 5-fluorocytosine intracellularly into the cytotoxic 5-fluorouracil. We have shown in experiments in vitro, involving a simulated desmoplastic pancreatic tumor, that the combined action of these targeted exosomes could be an approach for pancreatic ductal adenocarcinoma treatment.