Recombinant toxin DAB₃₈₉EGF is cytotoxic to human pancreatic cancer cells

Few malignancies have frustrated the persistent efforts of the oncologist like pancreatic cancer. Pancreatic cancer is usually unresectable at the time of diagnosis because of metastasis or local extension. Despite the aggressive nature of this deadly disease, systemic treatment options are limited. Even the recent introduction of the deoxycytidine analogue gemcitabine does not extend median survival of responders beyond a year. Clearly, alternative, more effective regimens are needed for treating pancreatic carcinoma. In pancreatic cancer, there is overexpression of growth factors and growth factor receptors, including epidermal growth factor receptor (EGFR). Targeted toxins consist of a targeting polypeptide covalently linked to a peptide toxin. DAB ₃₈₉EGF is a fusion protein composed of the catalytic and translocation domains of diphtheria toxin fused via a His-Ala linker to human epidermal growth factor (EGF). The authors have previously shown that DAB ₃₈₉EGF is selectively toxic to EGFR-overexpressing cells, including human brain tumour and lung carcinoma cell lines. Pancreatic adenocarcinoma should be responsive to this fusion protein based on its EGFR overexpression. However, the cytotoxic effect of DAB₃₈₉EGF on human pancreatic carcinoma cell lines has yet to be explored. The authors describe preliminary data showing the potent cytotoxicity of DAB₃₈₉EGF to human pancreatic carcinoma cell lines. Because of the non-specific toxicity to liver and kidney (which possess EGFR) of systemic administration, they also propose a potential novel drug delivery system for direct toxin implantation into pancreatic tumours using endoscopic ultrasound guided fine-needle injection (EUS-FNI). Hopefully, the use of these targeted therapeutic approaches in combination with other modalities may further extend survival and quality of life in patients with pancreatic adenocarcinoma.