Abstract 722: Evaluation of a chimeric anti CEA-conjugated antibody with AlexaFlour or Dylight fluorescent dyes for imaging pancreatic cancer in orthotopic nude mouse models.
Authors: Maawy Ali A. , Kaushal Sharmeela , Snyder Cynthia S. , Luiken George A. , Talamini Mark A. , Hoffman Robert M. , Bouvet Michael 
Published: August 2014

In this study, we evaluated multiple wavelengths of different fluorophores of the AlexaFlour (Invitrogen) and Dylight (Thermofisher scientific) series of fluorescent probes for labeling of mouse models of pancreatic cancer. BxPC-3 human pancreatic cancer cells were cultured in-vitro and subsequently injected subcutaneously in nude mice. After the development of subcutaneous tumors, the tumors were harvested and orthotopically implanted into the pancreatic tails of nude mice (1x1 mm fragments). The following fluorescent dyes were evaluated: 488 group (Alexa 488 and Dylight 488); 550 group (Alexa 555 and Dylight 550); 650 group (Alexa 660 and Dylight 650). The dyes were conjugated to chimeric anti-CEA antibody at a ratio of 3-4moles of dye per mole of protein. 50-100 μg of the fluorophore conjugated antibody was injected per mouse intravenously. Mice were then imaged with the OV100 Small Animal Imager (Olympus Corp, Tokyo, Japan). Whole body and intravital imaging were done at various time points (post implantation day 7-14). Mice that had tumor visible on whole body imaging were sacrificed, after which tumor depth, size, weight and fluorescence intensity were recorded. The smallest tumor size was first discernible on whole body imaging with the 650 group of dyes, followed by the 550 group and finally the 488 group with significantly larger tumors. The fluorescence intensity of the Dylight panel of dyes overall was brighter than the AlexaFluor dyes and therefore able to detect smaller and deeper tumors. The 550 and 650 group of dyes had the least amount background fluorescence with the highest amount of tumor to normal tissue contrast. In evaluation of tumor depth the 650 group of dyes were able to detect the deepest tumors; of the group the 488 group had the least tissue penetrance. In this study, the Dylight group of dyes had brighter conjugates with better tissue penetration and tumor delineation when compared to the AlexaFluor dyes. The 650 group of dyes had the most tissue penetration. The 550 group of dyes had similar background autofluorescence to the 650 group that was signficantly less than the 488 group. Both the 550 and 650 group had the highest tumor to background ratio of fluoresence that allows for very high fidelity in the delineation of neoplastic tissue from normal tissue.

Citation Format: Ali A. Maawy, Sharmeela Kaushal, Cynthia S. Snyder, George A. Luiken, Mark A. Talamini, Robert M. Hoffman, Michael Bouvet. Evaluation of a chimeric anti CEA-conjugated antibody with AlexaFlour or Dylight fluorescent dyes for imaging pancreatic cancer in orthotopic nude mouse models. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 722. doi:10.1158/1538-7445.AM2013-722