Molecular in vivo imaging of gastric cancer in a human-murine xenograft model: targeting epidermal growth factor receptor

Targeting Patient-Derived Orthotopic Gastric Cancers with a Fluorescent Humanized Anti-CEA Antibody

BACKGROUND

Gastric cancer poses a major diagnostic and therapeutic challenge as surgical resection provides the only opportunity for a cure. Specific labeling of gastric cancer could distinguish resectable and nonresectable disease and facilitate an R0 resection, which could improve survival.

METHODS

Two patient-derived gastric cancer lines, KG8 and KG10, were established from surgical specimens of two patients who underwent gastrectomy for gastric adenocarcinoma. Harvested tumor fragments were implanted into the greater curvature of the stomach to establish patient-derived orthotopic xenograft (PDOX) models. M5A (humanized anti-CEA antibody) or IgG control antibodies were conjugated with the near-infrared dye IRDye800CW. Mice received 50 µg of M5A-IR800 or 50 µg of IgG-IR800 intravenously and were imaged after 72 hr. Fluorescence imaging was performed by using the LI-COR Pearl Imaging System. A tumor-to-background ratio (TBR) was calculated by dividing the mean fluorescence intensity of the tumor versus adjacent stomach tissue.

RESULTS

M5A-IR800 administration resulted in bright labeling of both KG8 and K10 tumors. In the KG8 PDOX models, the TBR for M5A-IR800 was 5.85 (SE ± 1.64) compared with IgG-IR800 at 0.70 (SE ± 0.17). The K10 PDOX models had a TBR of 3.71 (SE ± 0.73) for M5A-IR800 compared with 0.66 (SE ± 0.12) for IgG-IR800.

CONCLUSIONS

Humanized anti-CEA (M5A) antibodies conjugated to fluorescent dyes provide bright and specific labeling of gastric cancer PDOX models. This tumor-specific fluorescent antibody is a promising potential clinical tool to detect the extent of disease for the determination of resectability as well as to visualize tumor margins during gastric cancer resection.

Toward next-generation endoscopes integrating biomimetic video systems, nonlinear optical microscopy, and deep learning

According to the World Health Organization, the proportion of the world's population over 60 years will approximately double by 2050. This progressive increase in the elderly population will lead to a dramatic growth of age-related diseases, resulting in tremendous pressure on the sustainability of healthcare systems globally. In this context, finding more efficient ways to address cancers, a set of diseases whose incidence is correlated with age, is of utmost importance. Prevention of cancers to decrease morbidity relies on the identification of precursor lesions before the onset of the disease, or at least diagnosis at an early stage. In this article, after briefly discussing some of the most prominent endoscopic approaches for gastric cancer diagnostics, we review relevant progress in three emerging technologies that have significant potential to play pivotal roles in next-generation endoscopy systems: biomimetic vision (with special focus on compound eye cameras), non-linear optical microscopies, and Deep Learning. Such systems are urgently needed to enhance the three major steps required for the successful diagnostics of gastrointestinal cancers: detection, characterization, and confirmation of suspicious lesions. In the final part, we discuss challenges that lie en route to translating these technologies to next-generation endoscopes that could enhance gastrointestinal imaging, and depict a possible configuration of a system capable of (i) biomimetic endoscopic vision enabling easier detection of lesions, (ii) label-free in vivo tissue characterization, and (iii) intelligently automated gastrointestinal cancer diagnostic.

Confocal laser endomicroscopy in gastro-intestinal endoscopy: technical aspects and clinical applications

Confocal laser endomicroscopy (CLE) is an advanced endoscopic imaging technology that provides a magnified, cellular level view of gastrointestinal epithelia. In conjunction with topical or intravenous fluorescent dyes, CLE allows for an "optical biopsy" for real-time diagnosis. Two different CLE system have been used in clinical endoscopy, probe-based CLE (pCLE) and endoscope-based CLE (eCLE). Using pCLE, the device can be delivered: (I) into the luminal gastrointestinal tract through the working channel of standard endoscopes; (II) into extraluminal cystic and solid parenchymal lesions through an endoscopic ultrasound (EUS) needle; or (III) into the biliary system through an endoscopic retrograde cholangiopancreatography (ERCP) accessory channel. With eCLE, the probe is directly integrated into the tip of a conventional endoscope, however, these endoscopes are no longer commercially available. CLE has moderate to high diagnostic accuracy for neoplastic and inflammatory conditions through the gastrointestinal tract including: oesophageal, gastric and colonic neoplasia, pancreatic cysts and solid lesions, malignant pancreatobiliary strictures and inflammatory bowel disease. Some studies have demonstrated the diagnostic benefit of CLE imaging when combined with either conventional white light endoscopy or advanced imaging technologies. Therefore, optical biopsies using CLE can resolve diagnostic dilemmas in some cases where conventional imaging fails to achieve conclusive results. CLE could also reduce the requirement for extensive tissue sampling during surveillance procedures. In the future, CLE in combination with molecular probes, could allow for the molecular characterization of diseases and assess response to targeted therapy. However, the narrow field of view, high capital costs and specialized operator training requirements remain the main limitations. Future multi-center, randomized trials with a focus on conventional diagnostic applications, cost-effectiveness and standardized training will be required for definitive evidence. The objective of this review is to evaluate the technical aspects and current applications of CLE in patients with gastrointestinal and pancreatobiliary diseases and discuss future directions for this technique.

Molecular mechanisms of chemo- and radiotherapy resistance and the potential implications for cancer treatment

Cancer is a leading cause of death worldwide. Surgery is the primary treatment approach for cancer, but the survival rate is very low due to the rapid progression of the disease and presence of local and distant metastasis at diagnosis. Adjuvant chemotherapy and radiotherapy are important components of the multidisciplinary approaches for cancer treatment. However, resistance to radiotherapy and chemotherapy may result in treatment failure or even cancer recurrence. Radioresistance in cancer is often caused by the repair response to radiation-induced DNA damage, cell cycle dysregulation, cancer stem cells (CSCs) resilience, and epithelial-mesenchymal transition (EMT). Understanding the molecular alterations that lead to radioresistance may provide new diagnostic markers and therapeutic targets to improve radiotherapy efficacy. Patients who develop resistance to chemotherapy drugs cannot benefit from the cytotoxicity induced by the prescribed drug and will likely have a poor outcome with these treatments. Chemotherapy often shows a low response rate due to various drug resistance mechanisms. This review focuses on the molecular mechanisms of radioresistance and chemoresistance in cancer and discusses recent developments in therapeutic strategies targeting chemoradiotherapy resistance to improve treatment outcomes.

Antibody-Targeted Imaging of Gastric Cancer

The specificity of antibodies for antigens overexpressed or uniquely expressed in tumor cells makes them ideal candidates in the development of bioconjugates for tumor imaging. Molecular imaging can aid clinicians in the diagnosis of gastric tumors and in selecting patients for therapies targeting receptors with a heterogeneous intratumoral or intertumoral expression. Antibodies labeled with an imaging radiometal can be used to detect primary tumors and metastases using whole-body positron emission tomography (PET) or single photon emission computed tomography (SPECT), both during diagnosis and monitoring disease response. Conjugated with fluorescent dyes, antibodies can image tumors by targeted optical imaging. This review provides an overview of the most recent advances in the use of antibodies labeled with radiometals or conjugated with fluorescent dyes for gastric cancer imaging.

Molecular endoscopic imaging: the future is bright

The prediction and final survival rate of gastrointestinal cancers are dependent on the stage of disease. The ideal would be to detect those gastrointestinal lesions at early stage or even premalignant forms which are difficult to detect by conventional endoscopy with white light optical imaging as they show minimum or no changes in morphological characteristics and are thus left untreated. The introduction of molecular imaging has greatly changed the pattern for detecting gastrointestinal lesions from purely macroscopic structural imaging to the molecular level. It allows microscopic examination of the gastrointestinal mucosa with endoscopy after the topical or systemic application of molecular probes. In recent years, major advancements in endoscopic instruments and specific molecular probes have been achieved. This review focuses on the current status of endoscopic imaging and highlights the application of molecular imaging in gastrointestinal and hepatic disease in the context of diagnosis and therapy based on recently published literature in this field. We also discuss the challenges of molecular endoscopic imaging, its future directions and potential that could have a tremendous impact on endoscopic research and clinical practice in future.

Molecular endoscopic imaging in cancer

Cancer is one of the major causes of death in both the USA and Europe. Molecular imaging is a novel field that is revolutionizing cancer management. It is based on the molecular signature of cells in order to study the human body both in normal and diseased conditions. The emergence of molecular imaging has been driven by the difficulties associated with cancer detection, particularly early-stage premalignant lesions which are often unnoticed as a result of minimal or no structural changes. Endoscopic surveillance is the standard method for early-stage cancer detection. In addition to recent major advancements in endoscopic instruments, significant progress has been achieved in the exploration of highly specific molecular probes and the combination of both will permit significant improvement of patient care. In this review, we provide an outline of the current status of endoscopic imaging and focus on recent applications of molecular imaging in gastrointestinal, hepatic and other cancers in the context of detection, targeted therapy and personalized medicine. As new imaging agents have the potential to broadly expand our cancer diagnostic capability, we will also present an overview of the main types of optical molecular probes with their pros and cons. We conclude by discussing the challenges and future prospects of the field.

A guide to multimodal endoscopy imaging for gastrointestinal malignancy - an early indicator

Multimodality imaging is an essential aspect of endoscopic surveillance for the detection of neoplastic lesions, such as dysplasia or intramucosal cancer, because it improves the efficacy of endoscopic surveillance and therapeutic procedures in the gastrointestinal tract. This approach reveals mucosal abnormalities that cannot be detected by standard endoscopy. Currently, these imaging techniques are divided into those for primary detection and those for targeted imaging and characterization, the latter being used to visualize areas of interest in detail and permit histological evaluation. This Review outlines the use of virtual chromoendoscopy, narrow-band imaging, autofluorescence imaging, optical coherence tomography, confocal endomicroscopy and volumetric laser endomicroscopy as new imaging techniques for diagnostic investigation of the gastrointestinal tract. Insights into use of multimodal endoscopic imaging for early disease detection, in particular for pre-malignant lesions, in the oesophagus, stomach and colon are described.

Intraoperative Gastroscopy for Tumor Localization in Laparoscopic Surgery for Gastric Adenocarcinoma

Determining resection margins for gastric cancer, which are not exposed to the serosal surface of the stomach, is the most important procedure during totally laparoscopic gastrectomy (TLG). The aim of this protocol is to introduce a procedure for intraoperative gastroscopy, in order to directly mark tumors during TLG for gastric cancer in the middle third of the stomach. Patients who were diagnosed with adenocarcinoma in the middle third of the stomach were enrolled in this case series. Before surgery, additional gastroscopy for tumor localization is not performed. Under general anesthesia, laparoscopic mobilization of the stomach is performed first. After the first portion of the duodenum is mobilized from the pancreas and clamped, the surgeon moves to the other side for the gastroscopic procedure. On the insertion of a gastroscope through the oral cavity into the stomach, 2 - 3 cc of indigo carmine is administered via an endoscopic injector into the gastric muscle layer at the proximal margin of the stomach. The location of stained serosa in the laparoscopic view is used to guide distal subtotal gastrectomy, however, total gastrectomy is performed if the tumor is too close to the esophagogastric junction. A specimen is sampled after distal gastrectomy to confirm sufficient length from resection margin to tumor before reconstruction. In our case series, all patients had tumor-free margins and required no additional resection. There was no morbidity related to the gastroscopic procedure, and the time required for the procedure has gradually decreased to about five minutes. Intraoperative gastroscopy for tumor localization is an accurate and tolerated method for gastric cancer patients undergoing totally laparoscopic distal gastrectomy.

Advanced gastrointestinal endoscopic imaging for inflammatory bowel diseases

Gastrointestinal luminal endoscopy is of paramount importance for diagnosis, monitoring and dysplasia surveillance in patients with both, Crohn's disease and ulcerative colitis. Moreover, with the recent recognition that mucosal healing is directly linked to the clinical outcome of patients with inflammatory bowel disorders, a growing demand exists for the precise, timely and detailed endoscopic assessment of superficial mucosal layer. Further, the novel field of molecular imaging has tremendously expanded the clinical utility and applications of modern endoscopy, now encompassing not only diagnosis, surveillance, and treatment but also the prediction of individual therapeutic responses. Within this review, we describe how novel endoscopic approaches and advanced endoscopic imaging methods such as high definition and high magnification endoscopy, dye-based and dye-less chromoendoscopy, confocal laser endomicroscopy, endocytoscopy and molecular imaging now allow for the precise and ultrastructural assessment of mucosal inflammation and describe the potential of these techniques for dysplasia detection.

Endoscopic molecular imaging of gastrointestinal tumors

In China, the incidence and mortality of gastrointestinal cancers are high, and early diagnosis is the key to improving the survival rate. In recent years, endoscopic molecular imaging in tumor diagnosis with its unique advantages has attracted more and more attention. With the rapid development of molecular biology, the mechanism of tumor occurrence and development has been gradually elucidated. The advent of fluorescent labeled molecular probes and targeted binding to molecular targets of gastrointestinal tumors makes it possible achieve real-time endoscopic molecular diagnosis of digestive tract tumors, which has a significant impact on tumor targeted therapy. In this paper, we review the progress in endoscopic molecular imaging of digestive tract tumors.

From the surface to the single cell: Novel endoscopic approaches in inflammatory bowel disease

Inflammatory bowel diseases (IBD) comprise the two major entities Crohn's disease and ulcerative colitis and endoscopic imaging of the gastrointestinal tract has always been an integral and central part in the management of IBD patients. Within the recent years, mucosal healing emerged as a key treatment goal in IBD that substantially decides about the clinical outcome of IBD patients, thereby demanding for a precise, timely and detailed endoscopic assessment of the mucosal inflammation associated with IBD. Further, molecular imaging has tremendously expanded the clinical utility and applications of modern endoscopy, now encompassing not only diagnosis, surveillance, and treatment but also the prediction of individual therapy response. Within this review we describe novel endoscopic approaches and advanced endoscopic imaging methods for the diagnosis, treatment and surveillance of IBD patients. We begin by providing an overview over novel and advanced imaging techniques such as magnification endoscopy and dye-based and dye-less chromoendoscopy, endomicroscopy and endocytoscopy. We then describe how these techniques can be utilized for the precise and ultrastructural assessment of mucosal inflammation and dysplasia development associated with IBD and outline how they have enabled the endoscopist to gain insight onto the cellular level in real-time. Finally, we provide an outlook on how molecular imaging has rapidly evolved in the recent past and can be used to make individual predictions about the therapeutic response towards biological treatment.

Characterization of lesions in the stomach: will confocal laser endomicroscopy replace the pathologist?

Confocal laser endomicroscopy (CLE) permits microscopic visualization of the mucosa during endoscopy at an approximately 1000fold magnification, permitting endoscopists to obtain microscopic analysis during gastroscopy. This can result in optimized diagnosis of diffuse alterations such as gastric atrophy and intestinal metaplasia and may limit the sampling error of untargeted biopsies. It also allows risk stratification prior to endoscopic therapy of neoplastic lesions of the stomach. In these areas, CLE represents a valuable adjunct for targeted histopathology. In addition, CLE allows on-site in vivo imaging, and by this insight into physiologic and pathophysiologic as well as molecular events of the stomach without major artifacts.

Human epidermal growth factor receptor 2 testing in gastric and gastroesophageal junction adenocarcinomas: role of the gastroenterologist

Endoscopic biopsy sampling of a gastric or GEJ mass is no longer just for histologic diagnosis. The biopsy material may be used for ancillary IHC and/or DNA testing. When possible, multiple biopsy specimens for sampling different areas of the tumor should be obtained to provide the best opportunity to identify overexpression of HER2 and abnormalities in other genes/proteins that may be expressed in different areas of the tumor. Thorough sampling at the time of initial diagnosis may prevent the need for future endoscopic procedures for the sole purpose of obtaining additional tissue for biomarker studies. Communication and coordination with oncologists and pathologists is essential to ensure an appropriate HER2 evaluation is performed. In the coming age of targeted therapeutics, endoscopy may not only be used to obtain tissue for histology and biomarker evaluation but may also be used for the direct in vivo evaluation of biomarkers that guide therapy.

Advanced endoscopic imaging for gastric cancer assessment: new insights with new optics?

The most immediate strategy for improving survival of gastric cancer patients is secondary prevention through diagnosis of early gastric cancer either through screening or follow-up of individuals at high risk. Endoscopy examination is therefore of paramount importance and two general steps are to be known in assessing gastric mucosa - detection and characterization. Over the past decade, the advent of advanced endoscopic imaging technology led to diverse descriptions of these modalities reporting them to be useful in this setting. In this review, we aim at summarizing the current evidence on the use of advance imaging in individuals at high-risk (i.e., advance stages of gastric atrophy/intestinal metaplasia) and in those harbouring neoplastic lesions, and address its potential usefulness providing the readers a framework to use in daily practice. Further research is also suggested.

Novel imaging modalities for immune cell monitoring in the intestine

PURPOSE OF REVIEW

The introduction of novel molecular imaging modalities that can not only define disease states on the basis of structural changes and morphology, but also allow in-vivo visualization and characterization of molecular and biochemical alterations on a cellular level add a new dimension to our current diagnostic possibilities. The advents of innovative endoscopic devices coupled with the introduction of novel targeting ligands contribute to the recent advances made in the field of molecular imaging. The purpose of this review is to present and discuss the concepts and the potential of novel endoscopic imaging modalities for immune cell monitoring in the intestine.

RECENT FINDINGS

Recent progress concerning molecular imaging studies in animals and human patients implicates that this approach can be used to improve detection of mucosal lesions in wide-field imaging and for in-vivo characterization of the mucosa with the ultimate goal of assessing the likelihood of response to targeted therapy with biological agents. In particular, molecular endomicroscopy for assessment of mucosal immune responses ('immunoendoscopy') emerges as a novel approach for optimized endoscopic diagnosis and individualized therapy.

SUMMARY

Molecular imaging modalities in the intestine have the immediate potential to have an impact on current clinical practice and could therefore open new frontiers for clinical endoscopy and give hope for improved diagnosis and targeted therapies.

Advances in imaging probes and optical microendoscopic imaging techniques for early in vivo cancer assessment

A new chapter in the history of medical diagnosis happened when the first X-ray technology was invented in the late 1800s. Since then, many non-invasive and minimally invasive imaging techniques have been invented for clinical diagnosis to research in cellular biology, drug discovery, and disease monitoring. These imaging modalities have leveraged the benefits of significant advances in computer, electronics, and information technology and, more recently, targeted molecular imaging. The development of targeted contrast agents such as fluorescent and nanoparticle probes coupled with optical imaging techniques has made it possible to selectively view specific biological events and processes in both in vivo and ex vivo systems with great sensitivity and selectivity. Thus, the combination of targeted molecular imaging probes and optical imaging techniques have become a mainstay in modern medicinal and biological research. Many promising results have demonstrated great potentials to translate to clinical applications. In this review, we describe a discussion of employing imaging probes and optical microendoscopic imaging techniques for cancer diagnosis.

An EGFR targeted PET imaging probe for the detection of colonic adenocarcinomas in the setting of colitis

Colorectal cancer is a serious complication associated with inflammatory bowel disease, often indistinguishable by screening with conventional FDG PET probes. We have developed an alternative EGFR-targeted PET imaging probe that may be used to overcome this difficulty, and successfully assessed its utility for neoplastic lesion detection in preclinical models. Cetuximab F(ab′)2 fragments were enzymatically generated, purified, and DOTA-conjugated. Radiolabeling was performed with ⁶⁷Ga for cell based studies and ⁶⁴Cu for in vivo imaging. Competitive binding studies were performed on CT26 cells to assess affinity (K_D) and receptors per cell (B_max). In vivo imaging using the EGFR targeted PET probe and ¹⁸F FDG was performed on CT26 tumor bearing mice in both control and dextran sodium sulfate (DSS) induced colitis settings. Spontaneous adenomas in genetically engineered mouse (GEM) models of colon cancer were additionally imaged. The EGFR imaging agent was generated with high purity (> 98%), with a labeling efficiency of 60 ± 5% and ≥99% radiochemical purity. The K_D was 6.6 ± 0.7 nM and the B_max for CT26 cells was 3.3 ± 0.1 × 10⁶ receptors/cell. Target to background ratios (TBR) for CT26 tumors compared to colonic uptake demonstrated high values for both ¹⁸F-FDG (3.95 ± 0.13) and the developed ⁶⁴Cu-DOTA-cetuximab-F(ab′)2 probe (4.42 ± 0.11) in control mice. The TBR for the EGFR targeted probe remained high (3.78 ± 0.06) in the setting of colitis, while for ¹⁸F FDG, this was markedly reduced (1.54 ± 0.08). Assessment of the EGFR targeted probe in the GEM models demonstrated a correlation between radiotracer uptake in spontaneous colonic lesions and the EGFR staining level ex vivo. A clinically translatable PET imaging probe was successfully developed to assess EGFR. The imaging agent can detect colonic tumors with a high TBR for detection of in situ lesions in the setting of colitis, and opens the possibility for a new approach for screening high-risk patients.

Molecular confocal laser endomicroscopy: A novel technique for in vivo cellular characterization of gastrointestinal lesions

While flexible endoscopy is essential for macroscopic evaluation, confocal laser endomicroscopy (CLE) has recently emerged as an endoscopic method enabling visualization at a cellular level. Two systems are currently available, one based on miniprobes that can be inserted via a conventional endoscope or via a needle guided by endoscopic ultrasound. The second system has a confocal microscope integrated into the distal part of an endoscope. By adding molecular probes like fluorescein conjugated antibodies or fluorescent peptides to this procedure (either topically or systemically administered during on-going endoscopy), a novel world of molecular evaluation opens up. The method of molecular CLE could potentially be used for estimating the expression of important receptors in carcinomas, subsequently resulting in immediate individualization of treatment regimens, but also for improving the diagnostic accuracy of endoscopic procedures by identifying otherwise invisible mucosal lesions. Furthermore, studies have shown that fluorescein labelled drugs can be used to estimate the affinity of the drug to a target organ, which probably can be correlated to the efficacy of the drug. However, several of the studies in this research field have been conducted in animal facilities or in vitro, while only a limited number of trials have actually been carried out in vivo. Therefore, safety issues still needs further evaluations. This review will present an overview of the implications and pitfalls, as well as future challenges of molecular CLE in gastrointestinal diseases.

Molecular imaging in endoscopy

Molecular imaging focuses on the molecular signature of cells rather than morphological changes in the tissue. The need for this novel type of imaging arises from the often difficult detection and characterization especially of small and/or premalignant lesions. Molecular imaging specifically visualizes biological properties of a lesion and might thereby be able to close diagnostic gaps, e.g. when differentiating hyperplastic from neoplastic polyps or detecting the margins of intraepithelial neoplastic spread. Additionally, not only the detection and discrimination of lesions could be improved: based on the molecular features identified using molecular imaging, therapy regimens could be adjusted on the day of diagnosis to allow for personalized medicine and optimized care for each individual patient.

Endoscopic molecular imaging of cancer

White light endoscopy has proven to be a very powerful tool in oncology. There is still, however, a need for better endoscopic techniques to overcome the current limitations of white light optics. New technologies that allow higher sensitivity, improved microanatomy and molecular characterization have been available for in vitro microscopy and are now being translated into in vivo endoscopy. Endoscopic molecular imaging is still in its infancy but holds the promise for enhancing sensitivity for early lesions, thus allowing earlier diagnosis and enabling early image-guided endoscopic intervention. A key feature of endoscopic molecular imaging is its increased sensitivity and specificity, which will be illustrated in this article, as well as describing perspectives on its future use in oncologic surgery.

In vivo molecular imaging of HER2 expression in a rat model of Barrett's esophagus adenocarcinoma

Human epidermal growth factor receptor 2 (HER2) is involved in the malignant progression of several human cancers, including esophageal adenocarcinoma (EAC). The purpose of this study was to evaluate HER2 overexpression and to explore the feasibility of confocal laser endomicroscopy for in vivo molecular imaging of HER2 status in an animal model of Barrett's-related EAC. Rats underwent esophagojejunostomy with gastric preservation. At 30 weeks post-surgery, the esophagus of 46 rats was studied; endoscopic and histological findings were correlated with HER2 immunofluorescence on excised biopsies and gross specimens. At this age, 23/46 rats developed Barrett's esophagus (BE), and 6/46 had cancer (four EAC and two squamous cell carcinomas). A significant overexpression of HER2 was observed in esophageal adenocarcinoma compared with normal squamous esophagus (9.4-fold) and BE (6.0-fold). AKT and its phosphorylated form were also overexpressed in cancer areas. Molecular imaging was performed at 80 weeks post-surgery in four rats after tail injection of fluorescent-labeled anti-HER2 antibody. At this age, 3/4 rats developed advance adenocarcinoma and showed in vivo overexpression of HER2 by molecular confocal laser endomicroscopy with heterogeneous distribution within cancer; no HER2 signal was observed in normal or Barrett's tissues. Therefore, HER2 overexpression is a typical feature of the surgical induced model of EAC that can be easily quantified in vivo using an innovative mini-invasive approach including confocal endomicroscopy; this approach may avoid limits of histological evaluation of HER2 status on 'blinded' biopsies.

Confocal laser endomicroscopy and molecular imaging in barrett esophagus and stomach

Detection of premalignant lesions in the upper gastrointestinal tract may facilitate endoscopic treatment and improve survival. Despite technological advances in white light endoscopy, its ability to detect premalignant lesions remains limited. Early detection could be improved by using advanced endoscopic imaging techniques, such as magnification endoscopy, narrow band imaging, i-scanning, flexible spectral imaging color enhancement, autofluorescence imaging, and confocal laser endomicroscopy (CLE), as these techniques may increase the rate of detection of mucosal abnormalities and allow optical diagnosis. The present review focuses on advanced endoscopic imaging techniques based on the use of CLE for diagnosing premalignant lesions in Barrett esophagus and stomach.

Molecular imaging in gastroenterology

Molecular imaging is a novel field in gastroenterology that uses fluorescently labelled probes to specifically highlight neoplastic lesions on the basis of their molecular signature. The development of molecular imaging has been driven by the need to improve endoscopic diagnosis and by progress in targeted therapies in gastrointestinal oncology to provide individualized treatment, which coincides with progress in endoscopy techniques and further miniaturization of detection devices. Different exogenous molecular probes for imaging include labelled antibodies, oligopeptides, affibodies(™) (Affibody AB, Bromma, Sweden), aptamers and activatable probes. Molecular imaging has been evaluated in two major indications: many trials have studied molecular imaging as a red flag technique to improve detection of lesions in wide-field imaging; on the other hand, microscopic analysis has been investigated for in vivo characterization of the molecular fingerprint of tumours with the ultimate goal of assessing the likelihood of response to targeted therapy. This Review focusses on the applications of molecular imaging that have immediate potential for translational science or imminent transition into clinical practice of gastrointestinal endoscopy.

Endoscopic molecular imaging: status and future perspective

During the last decade, researchers have made great progress in the development of new image processing technologies for gastrointestinal endoscopy. However, diagnosis using conventional endoscopy with white light optical imaging is essentially limited, and ultimately, we still rely on the histopathological diagnosis from biopsy specimens. Molecular imaging represents the most novel imaging methods in medicine, and the future of endoscopic diagnosis is likely to be impacted by a combination of biomarkers and technology. Endoscopic molecular imaging can be defined as the visualization of molecular characteristics with endoscopy. These innovations will allow us not only to locate a tumor or dysplastic lesion but also to visualize its molecular characteristics and the activity of specific molecules and biological processes that affect tumor behavior and/or its response to therapy. In the near future, these promising technologies will play a central role in endoluminal oncology.

Endomicroscopy and targeted imaging of gastric neoplasia

Confocal laser endomicroscopy (CLE) allows microscopic imaging of the gastric mucosa in real time during endoscopy. Gastroenterologists are able to evaluate gastric pathologies in real time, which is used to target fewer biopsies to regions of interest by providing multiple "optical" biopsies, and guide endoscopic interventions. CLE provides a powerful tool for translational studies to unravel the pathophysiology of diseases in vivo virtually free of artifacts. Molecular imaging may help to detect suspicious lesions and to predict response to targeted therapy. This review provides an overview of current applications of endomicroscopy of the stomach in clinical and translational science.

Clinical significance of nucleophosmin/B23 and human epidermal growth factor receptor 2/neu expressions in gastric cancers

The aim of the study was to investigate the expression levels of 'NPM'/nucleophosmin/B23 and human epidermal growth factor receptor 2 (Her-2)/neu in gastric cancer (GC) and corresponding non-malignant tissues, correlation with their clinicopathological parameters and the relationship of nucleophosmin/B23 and Her-2/neu in the occurrence and development of GC. A total of 131 postoperative patients were examined for nucleophosmin/B23 expression by immuno-histochemistry and for Her-2/neu expression by fluorescence in situ hybridization with the median follow-up period of 38 months. The positive expression rates of nucleophosmin (NPM) in neoplastic tissues and adjacent gastric mucosa were 65.6% and 52.7%, respectively. Nucleophosmin/B23 levels were linked to more advanced tumor stages, poor prognosis, and likelihood of recurrence (p < 0.05). The Cox multivariate analysis indicated that the nucleophosmin/B23 expression was an independent indicator for tumor recurrence (p = 0.011). Of the total GC specimens 12.21% were positive for Her-2/neu, but whose expression was of no correlation with patients' survival. Patients who were positive for Her-2/neu also had high NPM expression levels (p = 0.0303). The results suggest that nucleophosmin/B23 is a favorable prognostic indicator for GC. But Her-2/neu has no relationship with the prognosis of GC. The combined clinical significance of nucleophosmin/B23 and Her-2/neu remains to be further investigated.

Confocal Laser Endomicroscopy: Applications in Clinical and Translational Science—A Comprehensive Review

Confocal laser endomicroscopy (CLE) is a novel tool in the endoscopist’s armamentarium. It allows on-site histological information. The ability of gastroenterologists to interpret such microscopic information has been demonstrated in multiple studies from the upper and lower gastrointestinal tract. Recently, the field of application has expanded to provide hepatobiliary and intra-abdominal CLE imaging. CLE allows “smart,” targeted biopsies and is able to guide endoscopic interventions. But CLE is also translational in its approach and permits functional imaging that significantly impacts on our understanding of gastrointestinal diseases. Molecular imaging with CLE allows detection and characterization of lesions and may even be used for prediction of response to targeted therapy. This paper provides a comprehensive review over current applications of CLE in clinical applications and translational science.