Our imaging data convincingly demonstrate that targeting our polyplexes to EGFR allows strong transfection of pancreatic tumors with NIS. In a previous study, using the same vector construct in a subcutaneous hepatocellular carcinoma xenograft model, a tumor-absorbed dose of 47 mGy/MBq/g was calculated for 131I 24 h after polyplex administration [17], while in the current study, a dose of 74.7 mGy/MBq/g tumor 24 h post polyplex injection was achieved. The gene discussed is SLC5A5; the disease is hepatocellular carcinoma.