Pancreatic cancer and colon cancer metastasis are recalcitrant cancers that are often difficult to detect. Mucin 5AC (MUC5A) and Mucin 4 (MUC4) have been found to be overexpressed in pancreatic and colon cancers, respectively, while having minimal expression in normal tissue. Using Mucin antibodies conjugated to a fluorescent dye, we demonstrate their specific labeling of human derived pancreatic and colon cancers in both subcutaneous and orthotopic mouse models. Tumor-specific fluorescent antibodies are clinically promising tools for improving both oncologic resection and patient survival.
Background: Colon-cancer liver metastases is the frequent cause of death due to difficulties in visualizing margins of the metastases resulting in incomplete resection. To perform safer and more reliable liver surgery, indocyanine green (ICG) labeling has been used to visualize liver tumors and liver segment, but it is difficult to distinguish between a liver metastasis and its adjacent liver segment with traditional use of ICG alone. We have previously developed a method to label a liver metastasis with a tumor-specific fluorescent conjugated antibody and the adjacent liver segment with ICG in order to perform image guided metastasectomy. Methods: Nude mice were surgically orthotopically implanted with a human coloncancer cell-line or colon-cancer liver metastases derived from patients. After liver tumor growth, mice received near-infrared conjugated anti-CEA or anti-CEACAM antibody to label the liver metastases. ICG was intravenously injected after ligation of the left or left lateral Glissonean pedicle resulting in specific labeling of the segment adjacent to the tumor with preserved blood-flow in the liver. Imaging was performed with the FLARE Imaging Systems. Results: The liver metastasis was brightly labeled with near infrared fluorescence with selective tumor targeting by the fluorescent anti-CEA or anti-CEACAM antibody, which was imaged on the 700 nm channel. The adjacent liver segment with preserved bloodflow in the liver had a bright fluorescence ICG 800 nm signal, while the left or left lateral segment had no fluorescence signal. Overlay of the images showed clear color-coded differentiation between the tumor and the liver segment, enabling image guided metastasectomy. Conclusions: Color coded imaging of the liver metastasis and adjacent liver segment in the present review can be used in the future for improved liver metastasectomy in the clinic.
Introduction The 5 year survival rate of pancreatic cancer is <10%. Most patients have metastatic disease at time of diagnosis, often to the liver. Innovative imaging modalities, i.e. fluorescence guided surgery (FGS), may better appreciate metastatic disease and guide treatment. Mucin 4 (MUC4), a glycoprotein, is found in 89% of pancreatic cancers and absent in normal pancreatic tissue making it a candidate for tumor targeting in FGS. In the present study, a fluorescently-labeled MUC4 antibody preferentially targets patient pancreatic cancer in a mouse model. Methods and Materials A MUC4 antibody was conjugated to the infrared dye IRDye800CW (LICOR, Lincoln, NE) to synthesize MUC4-IR800. A high MUC4 expressing patient-derived hepatic metastatic pancreatic tumor (Panc Met) was divided into 1mm3 tumor fragments and implanted under the skin of the nude mouse. After the tumors grew ~5mm3, two mice received 50 μg and two mice received 75 μg of MUC4-IR800 via tail vein injection. Daily in-vivo imaging was performed with the Pearl Trilogy Imager (LICOR, Lincoln, NE) for 3 days. Tumor to background ratios (TBR) were calculated using skin as background. Results MUC4-IR800 selectively imaged the Panc Met tumors (see figure below). TBRs for all time points and doses were <2. The 75 μg arm had higher TBRs at 24 and 72 hours. At 48 hours, the TBRs were the same. Conclusion This present study demonstrated the successful targeting of a patient hepatic metastatic pancreatic cancer mouse model with MUC4-IR800. This has potential to improve metastatic pancreatic cancer detection. Future studies will be conducted with orthotopic models.
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