Uptake of verteporfin by orthotopic xenograft pancreas models with different levels of aggression

Pancreatic cancer is an aggressive disease with a poor prognosis, usually treated with chemoradiation therapy. Interstitial photodynamic therapy is a potentially effective adjuvant treatment that is under development. In the current study, two orthotopic pancreatic cancer models (AsPC-1 and Panc-1), have been characterized with respect to growth rates, morphology and liposomal drug (Verteporfin) uptake and distribution in SCID mice. Fluorescence of Verteporfin was measured in liver and tumor in vivo using a PDT fluorescence dosimeter with measurements taken before and up to one hour after tail vein injection. Fluorescence reached a plateau by about 15 minutes and did not decrease over the first hour. At time points from 15 minutes to 24 hrs, the internal organs (kidney, spleen, pancreas, tumor, muscle, lung, liver, and skin were excised and scanned on a Typhoon imager. The ratio of fluorescence in tumor versus normal tissues was analyzed with image processing, calculated at each time point and compared to in vivo results. Tissue distribution of Verteporfin in relation to functional vasculature marked by DiOc7 was carried out on frozen sections. Final analysis will result in determination of the ideal time point to administer light to achieve maximum tumor destruction while preserving normal tissue.