Background: The present study aimed to validate the accuracy of a tumor-specific antibody to target liver metastases of colorectal cancer. Methods: A humanized anti-CEA antibody conjugated to a fluorescent dye (M5A-IR800) was tested for targeting human colorectal cancer liver metastases (CRLMs) expressing luciferase in an orthotopic mouse model. Orthotopic mouse models of CRLMs were established by implanting fragments of a luciferase-expressing human colorectal cancer cell line, LS174T, in the liver of nude mice. Mice received 50 µg M5A-IR800 72 h prior to imaging. To test co-localization, bioluminescence imaging was performed using D-luciferin, which was given via intraperitoneal injection just prior to imaging. Results: Tumors were able to be visualized non-invasively through the skin with the luciferase–luciferin signal. Intra-abdominal imaging showed accurate labeling of CRLMs with M5A-IR800, which co-localized with the luciferase–luciferin signal. Conclusions: The present results validate the accuracy of a tumor-specific anti-CEA antibody in targeting liver metastases of colorectal cancer.

Background/Objectives: Pancreatic cancer is the fourth leading cause of deaths related to cancer. It is a highly aggressive malignancy and often metastasizes quickly to other parts of the body and organs. The most effective cure is surgical resection, which also is limited by tumor identification and clear tumor margin visualization. Previously, we used MUC4 antibodies labeled with IRDye800CW (anti-MUC4-IR800) to target primary human pancreatic cancer in orthotopic cell line mouse models. Methods: In the present study, we established a pancreatic cancer liver metastasis mouse model by implanting a tumor fragment in the liver and a peritoneal carcinomatosis mouse model by injecting pancreatic cancer cells interperitoneally. Once the tumors were established, anti-MUC4-IR800 was administered to the mice by tail vein injection. Laparotomy was performed and tumors were imaged under white-light and near-infrared (NIR) fluorescence with the Pearl Small Animal Imaging System. Results: NIR imaging after 72 h shows the bright targeting of pancreatic cancer metastasis in both mouse models with high tumor-to-background ratios. Conclusions: Anti-MUC4-IR800 was able to successfully target and brightly label metastatic pancreatic cancer as small as 1 mm. Future clinical applications of the results of the present study are discussed.