The present study reviews the use of tumor-specific antibodies conjugated to fluorescent dyes in preclinical and clinical studies to enhance visualization of primary tumors and metastases for fluorescence-guided surgery (FGS) in colorectal cancer (CRC). A search strategy was developed using the peer-reviewed National Center for Biotechnology Information (NCBI) database on PubMed. Studies using tumor-specific fluorescence imaging and FGS techniques on murine models of colorectal cell lines or patient-derived orthotopic xenograft (PDOX) colorectal cancer are reviewed. A total of 24 articles were identified that met the inclusion criteria, 21 preclinical and 3 clinical trials. The most widely used target antigen in preclinical and clinical trials was carcinoembryonic antigen (CEA). Mouse studies and clinical studies have demonstrated that the use of FGS in CRC can aid in decreased residual tumor and decreased rates of recurrence. As the mainstay of colorectal cancer treatment is surgery, the addition of intraoperative fluorescence imaging can help locate tumor margins, visualize occult micro-metastases, drive surgical decision making and improve patient outcomes.

Colorectal cancer (CRC) is a common cause of cancer and cancer-related death. Surgery is the only curative modality. Fluorescence-enhanced visualization of CRC with targeted fluorescent probes that can delineate boundaries and target tumor-specific biomarkers can increase rates of curative resection. Approaches to enhancing visualization of the tumor-to-normal tissue interface are active areas of investigation. Nonspecific dyes are the most-used approach, but tumor-specific targeting agents are progressing in clinical trials. The present narrative review describes the principles of fluorescence targeting of CRC for diagnosis and fluorescence-guided surgery with molecular biomarkers for preclinical or clinical evaluation.

Tumor-specific targeting with fluorescent probes can enhance contrast for identification of cancer during surgical resection and visualize otherwise invisible tumor margins. Nanobodies are the smallest naturally-occurring antigen-binding molecules with rapid pharmacokinetics. The present work demonstrates the efficacy of a fluorescent anti-CEA nanobody conjugated to an IR800 dye to target and label patient derived pancreatic cancer xenografts. After intravenous administration, the probe rapidly localized to the pancreatic cancer tumors within an hour and had a tumor-to-background ratio of 2.0 by 3 h. The fluorescence signal was durable over a prolonged period of time. With the rapid kinetics afforded by fluorescent nanobodies, both targeting and imaging can be performed on the same day as surgery.

Gastric cancer is the third leading cause of cancer-related deaths, with more than one million new cases and approximately 841,000 deaths annually worldwide. We report a case of a young patient (25 years old) with an aggressive form of gastric cancer. The patient had previously been treated for Helicobacter pylori (H. pylori), which is a main risk factor for developing gastric cancer. Genetic testing showed an E-cadherin (CDH1) germline mutation of unknown significance. After eight cycles of chemotherapy, a positron emission tomography (PET) scan showed disease progression with an enlarging hypermetabolic right adnexal mass suspicious for metastatic disease. Tumor pathology demonstrated invasive and poorly differentiated gastric carcinoma. The analysis of the tumor biopsy indicated the very high expression of a chemokine, C-X-C motif chemokine 5 (CXCL5). The combination of H. pylori infection with an existence of a rare CDH1 mutation could have contributed to this aggressive gastric cancer.

A major barrier to the diagnosis and effective treatment of solid-tumor cancers is the difficulty in detection and visualization of tumor margins in primary and metastatic disease. The use of fluorescence can augment the surgeon's ability to detect cancer and aid in its resection. Several cancer types express carcinoembryonic antigen (CEA) including colorectal, pancreatic and gastric cancer. Antibodies to CEA have been developed and tagged with near-infrared fluorescent dyes. This review article surveyed the use of CEA antibodies conjugated to fluorescent probes for in vivo studies since 1990. PubMed and Google Scholar databases were queried, and 900 titles and abstracts were screened. Fifty-nine entries were identified as possibly meeting inclusion/exclusion criteria and were reviewed in full. Forty articles were included in the review and their citations were screened for additional entries. A total of 44 articles were included in the final review. The use of fluorescent anti-CEA antibodies has been shown to improve detection and resection of tumors in both murine models and clinically. The cumulative results indicate that fluorescent-conjugated anti-CEA antibodies have important potential to improve cancer diagnosis and surgery. In an emerging technology, anti-CEA fluorescent antibodies have also been successfully used for photoimmunotherapy treatment for cancer.

Helicobacter pylori (H. pylori) infection is a known cause of many digestive diseases, including gastritis, peptic ulcers, and gastric cancer. However, the underlying mechanisms by which H. pylori infection triggers these disorders are still not clearly understood. Gastric cancer is a slow progressing disease, which makes it difficult to study. We have developed an accelerated disease progression mouse model, which leverages mice deficient in the myeloid differentiation primary response 88 gene (Myd88^-/-) infected with Helicobacter felis (H. felis). Using this model and gastric biopsy samples from patients, we report that activation of the Toll/interleukin-1 receptor (TIR)-domain-containing adaptor inducing interferon-β (TRIF)-type I interferon (IFN-I) signaling pathway promotes Helicobacter-induced disease progression toward severe gastric pathology and gastric cancer development. Further, results implicated downstream targets of this pathway in disease pathogenesis. These findings may facilitate stratification of Helicobacter-infected patients and thus enable treatment prioritization of patients.

Pancreatic cancer is a recalcitrant disease in which R0 resection is often not achieved owing to difficulty in visualization of the tumor margins and proximity of adjacent vessels. To improve outcomes, we have developed fluorescence-guided surgery (FGS) and photoimmunotherapy (PIT) using a fluorescent tumor-specific antibody. Nude mice received surgical orthotopic implantation (SOI) of the human pancreatic cancer cell line BxPC-3 expressing green fluorescent protein. An anti-carcinoembryonic antigen-related cell adhesion molecule (CEACAM) monoclonal antibody (6G5j) was conjugated to the 700-nm fluorescent dye IR700DyeDX (6G5j-IR700DX). Three weeks after SOI, 16 mice received 50 μg 6G5j-IR700DX via the tail vein 24 h before surgery and were randomized to two groups: FGS-only (n = 8) and FGS + PIT (n = 8). All tumors were imaged with the Pearl Trilogy imaging system and resected under the guidance of the FLARE imaging system. The FGS + PIT group received PIT of the post-surgical bed at an intensity of 150 mW/cm2 for 30 min. Mice were sacrificed 4 weeks after initial surgery, and tumors were imaged with a Dino-Lite digital microscope, excised, and weighed. The 6G5j-IR700DX dye illuminated the orthotopic pancreatic tumors for FGS and PIT. The metastatic recurrence rate was 100.0% for FGS-only and 25.0% for FGS + PIT (p = 0.007). The average total recurrent tumor weight was 2370.3 ± 1907.8 mg for FGS-only and 705.5 ± 1200.0 mg for FGS + PIT (p = 0.039). FGS and adjuvant PIT can be combined by using a single antibody-fluorophore conjugate to significantly reduce the frequency of pancreatic cancer recurrence.