Image-Guided Surgery in Patients with Pancreatic Cancer: First Results of a Clinical Trial Using SGM-101, a Novel Carcinoembryonic Antigen-Targeting, Near-Infrared Fluorescent Agent

Intraoperative molecular imaging of colorectal lung metastases with SGM-101: a feasibility study

PURPOSE

Metastasectomy is a common treatment option for patients with colorectal lung metastases (CLM). Challenges exist with margin assessment and identification of small nodules, especially during minimally invasive surgery. Intraoperative fluorescence imaging has the potential to overcome these challenges. The aim of this study was to assess feasibility of targeting CLM with the carcinoembryonic antigen (CEA) specific fluorescent tracer SGM-101.

METHODS

This was a prospective, open-label feasibility study. The primary outcome was the number of CLM that showed a true positive fluorescence signal with SGM-101. Fluorescence positive signal was defined as a signal-to-background ratio (SBR) ≥ 1.5. A secondary endpoint was the CEA expression in the colorectal lung metastases, assessed with the immunohistochemistry, and scored by the total immunostaining score.

RESULTS

Thirteen patients were included in this study. Positive fluorescence signal with in vivo, back table, and closed-field bread loaf imaging was observed in 31%, 45%, and 94% of the tumors respectively. Median SBRs for the three imaging modalities were 1.00 (IQR: 1.00-1.53), 1.45 (IQR: 1.00-1.89), and 4.81 (IQR: 2.70-7.41). All tumor lesions had a maximum total immunostaining score for CEA expression of 12/12.

CONCLUSION

This study demonstrated the potential of fluorescence imaging of CLM with SGM-101. CEA expression was observed in all tumors, and closed-field imaging showed excellent CEA specific targeting of the tracer to the tumor nodules. The full potential of SGM-101 for in vivo detection of the tracer can be achieved with improved minimal invasive imaging systems and optimal patient selection.

TRIAL REGISTRATION

The study was registered in ClinicalTrial.gov under identifier NCT04737213 at February 2021.

Ultrasound-Guided Quantitative Fluorescence Molecular Endoscopy for Monitoring Response in Patients with Esophageal Cancer Following Neoadjuvant Chemoradiotherapy

PURPOSE

The ability to identify residual tumor tissues in patients with locally advanced esophageal cancer following neoadjuvant chemoradiotherapy (nCRT) is essential for monitoring the treatment response. Using the fluorescent tracer bevacizumab-800CW, we evaluated whether ultrasound-guided quantitative fluorescent molecular endoscopy (US-qFME), which combines quantitative fluorescence molecular endoscopy (qFME) with ultrasound-guided needle biopsy/single-fiber fluorescence (USNB/SFF), can be used to identify residual tumor tissues in patients following nCRT.

EXPERIMENTAL DESIGN

Twenty patients received an additional endoscopy procedure the day before surgery. qFME was performed at the primary tumor site (PTS) and in healthy tissue to first establish the optimal tracer dose. USNB/SFF was then used to measure intrinsic fluorescence in the deeper PTS layers and lymph nodes (LN) suspected for metastasis. Finally, the intrinsic fluorescence and the tissue optical properties-specifically, the absorption and reduced scattering coefficients-were combined into a new parameter called omega.

RESULTS

First, a 25-mg bevacizumab-800CW dose allowed for clear differentiation between the PTS and healthy tissue, with a target-to-background ratio (TBR) of 2.98 (IQR, 1.86-3.03). Moreover, we found a clear difference between the deeper esophageal PTS layers and suspected LN compared to healthy tissues, with TBR values of 2.18 and 2.17, respectively. Finally, our new parameter, omega, further improved the ability to differentiate between the PTS and healthy tissue.

CONCLUSIONS

Combining bevacizumab-800CW with US-qFME may serve as a viable strategy for monitoring the response to nCRT in esophageal cancer and may help stratify patients regarding active surveillance versus surgery.

Intraoperative image-guidance during robotic surgery: is there clinical evidence of enhanced patient outcomes?

BACKGROUND

To date, the benefit of image guidance during robot-assisted surgery (IGS) is an object of debate. The current study aims to address the quality of the contemporary body of literature concerning IGS in robotic surgery throughout different surgical specialties.

METHODS

A systematic review of all English-language articles on IGS, from January 2013 to March 2023, was conducted using PubMed, Cochrane library's Central, EMBASE, MEDLINE, and Scopus databases. Comparative studies that tested performance of IGS vs control were included for the quantitative synthesis, which addressed outcomes analyzed in at least three studies: operative time, length of stay, blood loss, surgical margins, complications, number of nodal retrievals, metastatic nodes, ischemia time, and renal function loss. Bias-corrected ratio of means (ROM) and bias-corrected odds ratio (OR) compared continuous and dichotomous variables, respectively. Subgroup analyses according to guidance type (i.e., 3D virtual reality vs ultrasound vs near-infrared fluoresce) were performed.

RESULTS

Twenty-nine studies, based on 11 surgical procedures of three specialties (general surgery, gynecology, urology), were included in the quantitative synthesis. IGS was associated with 12% reduction in length of stay (ROM 0.88; p = 0.03) and 13% reduction in blood loss (ROM 0.87; p = 0.03) but did not affect operative time (ROM 1.00; p = 0.9), or complications (OR 0.93; p = 0.4). IGS was associated with an estimated 44% increase in mean number of removed nodes (ROM 1.44; p < 0.001), and a significantly higher rate of metastatic nodal disease (OR 1.82; p < 0.001), as well as a significantly lower rate of positive surgical margins (OR 0.62; p < 0.001). In nephron sparing surgery, IGS significantly decreased renal function loss (ROM 0.37; p = 0.002).

CONCLUSIONS

Robot-assisted surgery benefits from image guidance, especially in terms of pathologic outcomes, namely higher detection of metastatic nodes and lower surgical margins. Moreover, IGS enhances renal function preservation and lowers surgical blood loss.

Global trends in the application of fluorescence imaging in pancreatic diseases: a bibliometric and knowledge graph analysis

Background

In recent years, with the continuous development of fluorescence imaging technology, research on its application in pancreatic diseases has surged. This area is currently of high research interest and holds the potential to become a non-invasive and effective tool in the diagnosis and treatment of pancreatic diseases. The objective of this study is to explore the hotspots and trends in the field of fluorescence imaging technology applications in pancreatic diseases from 2003 to 2023 through bibliometric and visual analysis.

Methods

This study utilized the Web of Science (core collection) to identify publications related to the application of fluorescence imaging technology in pancreatic diseases from 2003 to 2023. Tools such as CiteSpace (V 6.2.R6), VOSviewer (v1.6.20), and R Studio (Bibliometrix: R-tool version 4.1.4) were employed to analyze various dimensions including publication count, countries, institutions, journals, authors, co-cited references, keywords, burst words, and references.

Results

A comprehensive analysis was conducted on 913 papers published from January 1, 2003, to December 1, 2023, on the application of fluorescence imaging technology in pancreatic diseases. The number of publications in this field has rapidly increased, with the United States being the central hub. The University of California, San Diego emerged as the most active institution. "Biomaterials" was identified as the most influential journal. Authors with the most publications and the highest average citations per article are Hoffman, Robert M. and Luiken, George A., respectively. Keywords such as pancreatic cancer, cancer, expression, indocyanine green, and nanoparticles received widespread attention, with indocyanine green and nanoparticles being current active research hotspots in the field.

Conclusion

This study is the first bibliometric analysis in the field of fluorescence imaging technology applications in pancreatic diseases. Our data will facilitate a better understanding of the developmental trends, identification of research hotspots, and direction in this field. The findings provide practical information for other scholars to grasp key directions and cutting-edge insights.

DOTA-Based Plectin-1 Targeted Contrast Agent Enables Detection of Pancreatic Cancer in Human Tissue

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive and lethal malignancy with extremely poor patient survival rates. A key reason for the poor prognosis is the lack of effective diagnostic tools to detect the disease at curable, premetastatic stages. Tumor surgical resection is PDAC's first-line treatment, however distinguishing between cancerous and healthy tissue with current imaging tools remains a challenge. In this work, we report a DOTA-based fluorescent probe targeting plectin-1 for imaging PDAC with high specificity. To enable heterogeneous functionalization of the DOTA-core with multiple targeting peptide units and the fluorophore, a novel, fully clickable synthetic route that proceeds in one pot was developed. Extensive validation of the probe set the stage for PDAC detection in mice and human tissue. Altogether, these findings may pave the way for improved clinical understanding and early detection of PDAC progression as well as more accurate resection criteria.

A systematic methodology review of fluorescence-guided cancer surgery to inform the development of a core master protocol and outcome set

BACKGROUND

Fluorescence-guided precision cancer surgery may improve survival and minimize patient morbidity. Efficient development of promising interventions is however hindered by a lack of common methodology. This methodology review aimed to synthesize descriptions of technique, governance processes, surgical learning and outcome reporting in studies of fluorescence-guided cancer surgery to provide guidance for the harmonized design of future studies.

METHODS

A systematic search of MEDLINE, EMBASE and CENTRAL databases from 2016-2020 identified studies of all designs describing the use of fluorescence in cancer surgery. Dual screening and data extraction was conducted by two independent teams.

RESULTS

Of 13,108 screened articles, 426 full text articles were included. The number of publications per year increased from 66 in 2016 to 115 in 2020. Indocyanine green was the most commonly used fluorescence agent (391, 91.8%). The most common reported purpose of fluorescence guided surgery was for lymph node mapping (195, 5%) and non-specific tumour visualization (94, 2%). Reporting about surgical learning and governance processes incomplete. A total of 2,577 verbatim outcomes were identified, with the commonly reported outcome lymph node detection (796, 30%). Measures of recurrence (32, 1.2%), change in operative plan (23, 0.9%), health economics (2, 0.1%), learning curve (2, 0.1%) and quality of life (2, 0.1%) were rarely reported.

CONCLUSION

There was evidence of methodological heterogeneity that may hinder efficient evaluation of fluorescence surgery. Harmonization of the design of future studies may streamline innovation.

Novel Near-Infrared Fluorescent Probe for Hepatocyte Growth Factor in Vivo Imaging in Surgical Navigation of Colorectal Cancer

Despite recent advancements in colorectal cancer (CRC) treatment, the prognosis remains unfavorable primarily due to high recurrence and liver metastasis rates. Fluorescence molecular imaging technologies, combined with specific probes, have gained prominence in facilitating real-time tumor resection guided by fluorescence. Hepatocyte growth factor (HGF) is overexpressed in CRC, but the advancement of HGF fluorescent probes has been impeded by the absence of effective HGF-targeting small-molecular ligands. Herein, we present the targeted capabilities of the novel V-1-GGGK-MPA probe labeled with a near-infrared fluorescent dye, which targets HGF in CRC. The V-1-GGGK peptide exhibits high specificity and selectivity for HGF-positive in vitro tumor cells and in vivo tumors. Biodistribution analysis of V-1-GGGK-MPA revealed tumor-specific accumulation with low background uptake, yielding signal-to-noise ratio (SNR) values of tumor-to-colorectal >6 in multiple subcutaneous CRC models 12 h postinjection. Quantitative analysis confirmed the probe's high uptake in SW480 and HT29 orthotopic and liver metastatic models, with SNR values of tumor-to-colorectal and -liver being 5.6 ± 0.4, 4.6 ± 0.5, and 2.1 ± 0.3, 2.0 ± 0.5, respectively, enabling precise tumor visualization for surgical navigation. Pathological analysis demonstrated the excellent tumor boundaries discrimination capacity of the V-1-GGGK-MPA probe at the molecular level. With its rapid tumor targeting, sustained tumor retention, and precise tumor boundary delineation, V-1-GGGK-MPA merges as a promising HGF imaging agent, enriching the toolbox of intraoperative navigational fluorescent probes for CRC.

Magnetic-optical dual-modality imaging monitoring chemotherapy efficacy of pancreatic ductal adenocarcinoma with a low-dose fibronectin-targeting Gd-based contrast agent

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is a lethal hypovascular tumor surrounded by dense fibrosis. Albumin-bound paclitaxel and gemcitabine (AG) chemotherapy is the mainstay of PDAC treatment through depleting peritumoral fibrosis and killing tumor cells; however, it remains challenging due to the lack of a noninvasive imaging method evaluating fibrotic changes during AG chemotherapy. In this study, we developed a dual-modality imaging platform that enables noninvasive, dynamic, and quantitative assessment of chemotherapy-induced fibrotic changes through near-infrared fluorescence molecular imaging (FMI) and magnetic resonance imaging (MRI) using an extradomain B fibronectin (EDB-FN)-targeted imaging probe (ZD2-Gd-DOTA-Cy7).

METHODS

The ZD2-Gd-DOTA-Cy7 probe was constructed by conjugating a peptide (Cys-TVRTSAD) to Gd-DOTA and the near-infrared dye Cy7. PDAC murine xenograft models were intravenously injected with ZD2-Gd-DOTA-Cy7 at a Gd concentration of 0.05 mmol/kg or free Cy7 and Gd-DOTA as control. The normalized tumor background ratio (TBR) on FMI and the T1 reduction ratio on MRI were quantitatively analyzed. For models receiving AG chemotherapy or saline, MRI/FMI was performed before and after treatment. Histological analyses were performed for validation.

RESULTS

The ZD2-Gd-DOTA-Cy7 concentration showed a linear correlation with the fluorescence intensity and T1 relaxation time in vitro. The optimal imaging time was 30 min after injection of the ZD2-Gd-DOTA-Cy7 (0.05 mmol/kg), only half of the clinic dosage of gadolinium. Additionally, ZD2-Gd-DOTA-Cy7 generated a 1.44-fold and 1.90-fold robust contrast enhancement compared with Cy7 (P < 0.05) and Gd-DOTA (P < 0.05), respectively. For AG chemotherapy monitoring, the T1 reduction ratio and normalized TBR in the fibrotic tumor areas were significantly increased by 1.99-fold (P < 0.05) and 1.78-fold (P < 0.05), respectively, in the control group compared with those in the AG group.

CONCLUSION

MRI/FMI with a low dose of ZD2-Gd-DOTA-Cy7 enables sensitive imaging of PDAC and the quantitative assessment of fibrotic changes during AG chemotherapy, which shows potential clinical applications for precise diagnosis, post-treatment monitoring, and disease management.

NIR-II Fluorescent Probes for Fluorescence-Imaging-Guided Tumor Surgery

Second near-infrared (NIR-II) fluorescence imaging is the most advanced imaging fidelity method with extraordinary penetration depth, signal-to-background ratio, biocompatibility, and targeting ability. It is currently booming in the medical realm to diagnose tumors and is being widely applied for fluorescence-imaging-guided tumor surgery. To efficiently execute this modern imaging modality, scientists have designed various probes capable of showing fluorescence in the NIR-II window. Here, we update the state-of-the-art NIR-II fluorescent probes in the most recent literature, including indocyanine green, NIR-II emissive cyanine dyes, BODIPY probes, aggregation-induced emission fluorophores, conjugated polymers, donor-acceptor-donor dyes, carbon nanotubes, and quantum dots for imaging-guided tumor surgery. Furthermore, we point out that the new materials with fluorescence in NIR-III and higher wavelength range to further optimize the imaging results in the medical realm are a new challenge for the scientific world. In general, we hope this review will serve as a handbook for researchers and students who have an interest in developing and applying fluorescent probes for NIR-II fluorescence-imaging-guided surgery and that it will expedite the clinical translation of the probes from bench to bedside.

Preclinical evaluation of AGTR1-Targeting molecular probe for colorectal cancer imaging in orthotopic and liver metastasis mouse models

Despite advancements in colorectal cancer (CRC) treatment, the prognosis remains unfavorable for patients with distant liver metastasis. Fluorescence molecular imaging with specific probes is increasingly used to guide CRC surgical resection in real-time and treatment planning. Here, we demonstrate the targeted imaging capacity of an MPA-PEG4-N3-Ang II probe labeled with near-infrared (NIR) fluorescent dye targeting the angiotensin II (Ang II) type 1 receptor (AGTR1) that is significantly upregulated in CRC. MPA-PEG4-N3-Ang II was highly selective and specific to in vitro tumor cells and in vivo tumors in a mouse CRC xenograft model. The favorable ex vivo imaging and in vivo biodistribution of MPA-PEG4-N3-Ang II afforded tumor-specific accumulation with low background and >10 contrast tumor-to-colorectal values in multiple subcutaneous CRC models at 8 h following injection. Biodistribution analysis confirmed the probe's high uptake in HT29 and HCT116 orthotopic and liver metastatic models of CRC with signal-to-noise ratio (SNR) values of tumor-to-colorectal and -liver fluorescence of 5.8 ± 0.6, 5.3 ± 0.7, and 2.7 ± 0.5, 2.6 ± 0.5, respectively, enabling high-contrast intraoperative tumor visualization for surgical navigation. Given its rapid tumor targeting, precise tumor boundary delineation, durable tumor retention and docking study, MPA-PEG4-N3-Ang II is a promising high-contrast imaging agent for the clinical detection of CRC.

Nerve Visualization using Phenoxazine-Based Near-Infrared Fluorophores to Guide Prostatectomy

Fluorescence-guided surgery (FGS) is poised to revolutionize surgical medicine through near-infrared (NIR) fluorophores for tissue- and disease-specific contrast. Clinical open and laparoscopic FGS vision systems operate nearly exclusively at NIR wavelengths. However, tissue-specific NIR contrast agents compatible with clinically available imaging systems are lacking, leaving nerve tissue identification during prostatectomy a persistent challenge. Here, it is shown that combining drug-like molecular design concepts and fluorophore chemistry enabled the production of a library of NIR phenoxazine-based fluorophores for intraoperative nerve-specific imaging. The lead candidate readily delineated prostatic nerves in the canine and iliac plexus in the swine using the clinical da Vinci Surgical System that has been popularized for minimally invasive prostatectomy procedures. These results demonstrate the feasibility of molecular engineering of NIR nerve-binding fluorophores for ready integration into the existing surgical workflow, paving the path for clinical translation to reduce morbidity from nerve injury for prostate cancer patients.

Consensus conference statement on fluorescence-guided surgery (FGS) ESSO course on fluorescence-guided surgery

BACKGROUND

Fluorescence-guided surgery (FGS) has emerged as an innovative technique with promising applications in various surgical specialties. However, clinical implementation is hampered by limited availability of evidence-based reference work supporting the translation towards standard-of-care use in surgical practice. Therefore, we developed a consensus statement on current applications of FGS.

METHODS

During an international FGS course, participants anonymously voted on 36 statements. Consensus was defined as agreement ≥70% with participation grade of ≥80%. All participants of the questionnaire were stratified for user and handling experience within five domains of applicability (lymphatics & lymph node imaging; tissue perfusion; biliary anatomy and urinary tracts; tumor imaging in colorectal, HPB, and endocrine surgery, and quantification and (tumor-) targeted imaging). Results were pooled to determine consensus for each statement within the respective sections based on the degree of agreement.

RESULTS

In total 43/52 (81%) course participants were eligible as voting members for consensus, comprising the expert panel (n = 12) and trained users (n = 31). Consensus was achieved in 17 out of 36 (45%) statements with highest level of agreement for application of FGS in tissue perfusion and biliary/urinary tract visualization (71% and 67%, respectively) and lowest within the tumor imaging section (0%).

CONCLUSIONS

FGS is currently established for tissue perfusion and vital structure imaging. Lymphatics & lymph node imaging in breast cancer and melanoma are evolving, and tumor tissue imaging holds promise in early-phase trials. Quantification and (tumor-)targeted imaging are advancing toward clinical validation. Additional research is needed for tumor imaging due to a lack of consensus.

Humanized Anti-Carcinoembryonic Antigen Antibodies Brightly Target and Label Gastric Cancer in Orthotopic Mouse Models

INTRODUCTION

Gastric cancer poses a major therapeutic challenge. Improved visualization of tumor margins at the time of gastrectomy with fluorescent tumor-specific antibodies could improve outcomes. The present report demonstrates the potential of targeting gastric cancer with a humanized anti-carcinoembryonic antigen (CEA) antibody in orthotopic mouse models.

METHODS

MKN45 cells were injected subcutaneously into nude mice to establish xenograft models. Tumor fragments collected from subcutaneous models were then implanted into the greater curvature of the stomach to establish orthotopic models. For tumor labeling, a humanized anti-CEA antibody (M5A) and IgG as a control, were conjugated with the near-infrared dye IRDye800CW. Time (24-72 h) and dose (50-100 μg) response curves were performed in subcutaneous models. Orthotopic models received 50 μg of M5A-IR800 or 50 μg IgG-IR800 as a control and were imaged after 72 h. Fluorescence imaging was performed on the mice using the LI-COR Pearl Imaging System.

RESULTS

In subcutaneous models, tumor to background ratios (TBRs) reached 8.85 at 72 h. Median TBRs of orthotopic model primary tumors were 6.25 (interquartile range [IQR] 6.03-7.12) for M5A-IR800 compared to 0.42 (IQR 0.38-0.54) for control. Abdominal wall metastasis median TBRs were 13.52 (IQR 12.79-13.76) for M5A-IR800 and 3.19 (IQR 2.65-3.73) for the control. Immunohistochemistry confirmed CEA expression within tumors.

CONCLUSIONS

Humanized anti-CEA antibodies conjugated to near-infrared dyes provide specific labeling of gastric cancers in mouse models. Orthotopic models demonstrated bright and specific labeling with TBRs greater than ten times that of control. This tumor-specific fluorescent antibody is a promising potential clinical tool for improving visualization of gastric cancer margins at time of surgical resection.

MamoRef: an optical mammography device using whole-field CW diffuse reflectance. Presentation, validation and preliminary clinical results

Objective.MamoRef is an mammography device that uses near-infrared light, designed to provide clinically relevant information for the screening of diseases of the breast. Using low power continuous wave lasers and a high sensitivity CCD (Charge-coupled device) that captures a diffusely reflected image of the tissue, MamoRef results in a versatile diagnostic tool that aims to fulfill a complementary role in the diagnosis of breast cancer providing information about the relative hemoglobin concentrations as well as oxygen saturation.Approach.We present the design and development of an initial prototype of MamoRef. To ensure its effectiveness, we conducted validation tests on both the theoretical basis of the reconstruction algorithm and the hardware design. Furthermore, we initiated a clinical feasibility study involving patients diagnosed with breast disease, thus evaluating the practical application and potential benefits of MamoRef in a real-world setting.Main results.Our study demonstrates the effectiveness of the reconstruction algorithm in recovering relative concentration differences among various chromophores, as confirmed by Monte Carlo simulations. These simulations show that the recovered data correlates well with the ground truth, with SSIMs of 0.8 or more. Additionally, the phantom experiments validate the hardware implementation. The initial clinical findings exhibit highly promising outcomes regarding MamoRef's ability to differentiate between lesions.Significance.MamoRef aims to be an advancement in the field of breast pathology screening and diagnostics, providing complementary information to standard diagnostic techniques. One of its main advantages is the ability of determining oxy/deoxyhemoglobin concentrations and oxygen saturation; this constitutes valuable complementary information to standard diagnostic techniques. Besides, MamoRef is a portable and relatively inexpensive device, intended to be not only used in specific medical imaging facilities. Finally, its use does not require external compression of the breast. The findings of this study underscore the potential of MamoRef in fulfilling this crucial role.

Fluorescent Probes for Imaging in Humans: Where Are We Now?

Optical imaging has become an indispensable technology in the clinic. The molecular design of cell-targeted and highly sensitive materials, the validation of specific disease biomarkers, and the rapid growth of clinically compatible instrumentation have altogether revolutionized the way we use optical imaging in clinical settings. One prime example is the application of cancer-targeted molecular imaging agents in both trials and routine clinical use to define the margins of tumors and to detect lesions that are "invisible" to the surgeons, leading to improved resection of malignant tissues without compromising viable structures. In this Perspective, we summarize some of the key research advances in chemistry, biology, and engineering that have accelerated the translation of optical imaging technologies for use in human patients. Finally, our paper comments on several research areas where further work will likely render the next generation of technologies for translational optical imaging.

Advancements in Intraoperative Near-Infrared Fluorescence Imaging for Accurate Tumor Resection: A Promising Technique for Improved Surgical Outcomes and Patient Survival

Clear surgical margins for solid tumor resection are essential for preventing cancer recurrence and improving overall patient survival. Complete resection of tumors is often limited by a surgeon's ability to accurately locate malignant tissues and differentiate them from healthy tissue. Therefore, techniques or imaging modalities are required that would ease the identification and resection of tumors by real-time intraoperative visualization of tumors. Although conventional imaging techniques such as positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), or radiography play an essential role in preoperative diagnostics, these cannot be utilized in intraoperative tumor detection due to their large size, high cost, long imaging time, and lack of cancer specificity. The inception of several imaging techniques has paved the way to intraoperative tumor margin detection with a high degree of sensitivity and specificity. Particularly, molecular imaging using near-infrared fluorescence (NIRF) based nanoprobes provides superior imaging quality due to high signal-to-noise ratio, deep penetration to tissues, and low autofluorescence, enabling accurate tumor resection and improved survival rates. In this review, we discuss the recent developments in imaging technologies, specifically focusing on NIRF nanoprobes that aid in highly specific intraoperative surgeries with real-time recognition of tumor margins.

Glycoprotein Receptor CEACAM5-Targeted Intraoperative Molecular Imaging Tracer in Non-Small Cell Lung Cancer

BACKGROUND

Intraoperative molecular imaging has emerged as a potential tool in addressing challenges faced during lung cancer surgery by localizing small lesions, ensuring negative margins, and identifying synchronous cancers. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) glycoprotein has emerged as a potential target in fluorescent labeling of non-small cell lung cancer given the high antigen density in tumor cells and absence of expression in normal parenchyma. The goal of our study was to determine whether anti-CEACAM5 targeted near-infrared fluorochrome could be a suitable target in non-small cell lung cancer.

METHODS

The CEACAM5 expression was evaluated in AB-12 (known negative control), HT29 (known positive control), and H460 (non-small cell lung cancer) cell lines by polymerase chain reaction. SGM-101, a CEACAM5 antibody, coupled with a BM-104 near-infrared fluorescent tracer was evaluated with dose escalation, in vitro cellular localization, and immunofluorescence microscopy. Subsequently, in vivo validation was performed in 52 athymic nude xenografts.

RESULTS

Polymerase chain reaction analysis demonstrated 3000x relative expression of CEACAM5 in HT-29 cells compared with AB-12. The H460 cells showed 1000x relative expression compared with AB12 (P < .05). Both HT29 and H460 cells showed tracer internalization with signal to background ratio of 4.5 (SD 0.34) whereas there was minimal uptake by AB12 cells with signal to background ratio 1.1 (SD 0.1; P < .05). There was linear fluorescence increase with increasing tracer dosing in receptor expressing cell lines. In preclinical models, HT-29 and H460 cells lines produced near-infrared fluorescence with average tumor to background ratio of 3.89 (SD 0.25) irrespective of tumor size compared with no fluorescence by AB12 tumors (P < .05). The CEACAM5 expressing tumors had excellent dye uptake compared with AB12 tumors.

CONCLUSIONS

CEACAM5 serves as a possible receptor for targeted intraoperative molecular imaging resections in lung cancer. This study sets a path for evaluation of CEACAM5 targets in future clinical trials.

Dual probe difference specimen imaging for prostate cancer margin assessment

Significance

Positive margin status due to incomplete removal of tumor tissue during radical prostatectomy for high-risk localized prostate cancer requires reoperation or adjuvant therapy, which increases morbidity and mortality. Adverse effects of prostate cancer treatments commonly include erectile dysfunction, urinary incontinence, and bowel dysfunction, making successful initial curative prostatectomy imperative.

Aim

Current intraoperative tumor margin assessment is largely limited to frozen section analysis, which is a lengthy, labor-intensive process that is obtrusive to the clinical workflow within the operating room (OR). Therefore, a rapid method for prostate cancer margin assessment in the OR could improve outcomes for patients.

Approach

Dual probe difference specimen imaging (DDSI), which uses paired antibody-based probes that are labeled with spectrally distinct fluorophores, was shown herein for prostate cancer margin assessment. The paired antibody-based probes consisted of a targeted probe to prostate-specific membrane antigen (PSMA) and an untargeted probe, which were used as a cocktail to stain resected murine tissue specimens including prostate tumor, adipose, muscle, and normal prostate. Ratiometric images (i.e., DDSI) of the difference between targeted and untargeted probe uptake were calculated and evaluated for accuracy using receiver operator characteristic curve analysis with area under the curve values used to evaluate the utility of the DDSI method to detect PSMA positive prostate cancer.

Results

Targeted and untargeted probe uptake was similar between the high and low PSMA expressing tumor due to nonspecific probe uptake after topical administration. The ratiometric DDSI approach showed substantial contrast difference between the PSMA positive tumors and their respective normal tissues (prostate, adipose, muscle). Furthermore, DDSI showed substantial contrast difference between the high PSMA expressing tumors and the minimally PSMA expressing tumors due to the ratiometric correction for the nonspecific uptake patterns in resected tissues.

Conclusions

Previous work has shown that ratiometic imaging has strong predictive value for breast cancer margin status using topical administration. Translation of the ratiometric DDSI methodology herein from breast to prostate cancers demonstrates it as a robust, ratiometric technique that provides a molecularly specific imaging modality for intraoperative margin detection. Using the validated DDSI protocol on resected prostate cancers permitted rapid and accurate assessment of PSMA status as a surrogate for prostate cancer margin status. Future studies will further evaluate the utility of this technology to quantitatively characterize prostate margin status using PSMA as a biomarker.

Novel GRPR-Targeting Peptide for Pancreatic Cancer Molecular Imaging in Orthotopic and Liver Metastasis Mouse Models

Despite advancements in pancreatic cancer treatment, it remains one of the most lethal malignancies with extremely poor diagnosis and prognosis. Herein, we demonstrated the efficiency of a novel peptide GB-6 labeled with a near-infrared (NIR) fluorescent dye 3H-indolium, 2-[2-[2-[(2-carboxyethyl)thio]-3-[2-[1,3-dihydro-3,3-dimethyl-5-sulfo-1-(3-sulfopropyl)-2H-indol-2-ylidene]ethylidene]-1-cyclohexen-1-yl]ethenyl]-3,3-dimethyl-5-sulfo-1-(3-sulfopropyl)-, inner salt (MPA) and radionuclide technetium-99m (99mTc) as targeting probes using the gastrin-releasing peptide receptor (GRPR) that is overexpressed in pancreatic cancer as the target. A short linear peptide with excellent in vivo stability was identified, and its radiotracer [99mTc]Tc-HYNIC-PEG4-GB-6 and the NIR probe MPA-PEG4-GB-6 exhibited selective and specific uptake by tumors in an SW1990 pancreatic cancer xenograft mouse model. The favorable biodistribution of the tracer [99mTc]Tc-HYNIC-PEG4-GB-6 in vivo afforded tumor-specific accumulation with high tumor-to-muscle and -bone contrasts and renal body clearance at 1 h after injection. The biodistribution analysis revealed that the tumor-to-pancreas and -intestine fluorescence signal ratios were 5.2 ± 0.3 and 6.3 ± 1.5, respectively, in the SW1990 subcutaneous xenograft model. Furthermore, the high signal accumulation in the orthotopic pancreatic and liver metastasis tumor models with tumor-to-pancreas and -liver fluorescence signal ratios of 7.66 ± 0.48 and 3.94 ± 0.47, respectively, enabled clear tumor visualization for intraoperative navigation. The rapid tumor targeting, precise tumor boundary delineation, chemical versatility, and high potency of the novel GB-6 peptide established it as a high-contrast imaging probe for the clinical detection of GRPR, with compelling additional potential in molecular-targeted therapy.

Intraoperative Imaging in Hepatopancreatobiliary Surgery

Hepatopancreatobiliary surgery belongs to one of the most complex fields of general surgery. An intricate and vital anatomy is accompanied by difficult distinctions of tumors from fibrosis and inflammation; the identification of precise tumor margins; or small, even disappearing, lesions on currently available imaging. The routine implementation of ultrasound use shifted the possibilities in the operating room, yet more precision is necessary to achieve negative resection margins. Modalities utilizing fluorescent-compatible dyes have proven their role in hepatopancreatobiliary surgery, although this is not yet a routine practice, as there are many limitations. Modalities, such as photoacoustic imaging or 3D holograms, are emerging but are mostly limited to preclinical settings. There is a need to identify and develop an ideal contrast agent capable of differentiating between malignant and benign tissue and to report on the prognostic benefits of implemented intraoperative imaging in order to navigate clinical translation. This review focuses on existing and developing imaging modalities for intraoperative use, tailored to the needs of hepatopancreatobiliary cancers. We will also cover the application of these imaging techniques to theranostics to achieve combined diagnostic and therapeutic potential.

Nerve-Sparing Gynecologic Surgery Enabled by A Near-Infrared Nerve-Specific Fluorophore Using Existing Clinical Fluorescence Imaging Systems

Patients undergoing gynecological procedures suffer from lasting side effects due to intraoperative nerve damage. Small, delicate nerves with complex and nonuniform branching patterns in the female pelvic neuroanatomy make nerve-sparing efforts during standard gynecological procedures such as hysterectomy, cystectomy, and colorectal cancer resection difficult, and thus many patients are left with incontinence and sexual dysfunction. Herein, a near-infrared (NIR) fluorescent nerve-specific contrast agent, LGW08-35, that is spectrally compatible with clinical fluorescence guided surgery (FGS) systems is formulated and characterized for rapid implementation for nerve-sparing gynecologic surgeries. The toxicology, pharmacokinetics (PK), and pharmacodynamics (PD) of micelle formulated LGW08-35 are examined, enabling the determination of the optimal imaging doses and time points, blood and tissue uptake parameters, and maximum tolerated dose (MTD). Application of the formulated fluorophore to imaging of female rat and swine pelvic neuroanatomy validates the continued clinical translation and use for real-time identification of important nerves such as the femoral, sciatic, lumbar, iliac, and hypogastric nerves. Further development of LGW08-35 for clinical use will unlock a valuable tool for surgeons in direct visualization of important nerves and contribute to the ongoing characterization of the female pelvic neuroanatomy to eliminate the debilitating side effects of nerve damage during gynecological procedures.

Highly Selective Targeting of Pancreatic Cancer in the Liver with a Near-Infrared Anti-MUC5AC Probe in a PDOX Mouse Model: A Proof-of-Concept Study

Accurately identifying metastatic disease is critical to directing the appropriate treatment in pancreatic cancer. Mucin 5AC is overexpressed in pancreatic cancer but absent in normal pancreas tissue. The present proof-of-concept study demonstrates the efficacy of an anti-mucin 5AC antibody conjugated to an IR800 dye (MUC5AC-IR800) to preferentially label a liver metastasis of pancreatic cancer (Panc Met) in a unique patient-derived orthotopic xenograft (PDOX) model. In orthotopic models, the mean tumor to background ratio was 1.787 (SD ± 0.336), and immunohistochemistry confirmed the expression of MUC5AC within tumor cells. MUC5AC-IR800 provides distinct visualization of pancreatic cancer liver metastasis in a PDOX mouse model, demonstrating its potential utility in staging laparoscopy and fluorescence-guided surgery.

Specific Targeting and Labeling of Colonic Polyps in CPC-APC Mice with Mucin 5AC Fluorescent Antibodies: A Model for Detection of Early Colon Cancer

Poor visualization of polyps can limit colorectal cancer screening. Fluorescent antibodies to mucin5AC (MUC5AC), a glycoprotein upregulated in adenomas and colorectal cancer, could improve screening colonoscopy polyp detection rate. Adenomatous polyposis coli flox mice with a Cdx2-Cre transgene (CPC-APC) develop colonic polyps that contain both dysplastic and malignant tissue. Mice received MUC5AC-IR800 or IRdye800 as a control IV and were sacrificed after 48 h for near-infrared imaging of their colons. A polyp-to-background ratio (PBR) was calculated for each polyp by dividing the mean fluorescence intensity of the polyp by the mean fluorescence intensity of the background tissue. The mean 25 μg PBR was 1.70 (±0.56); the mean 50 μg PBR was 2.64 (±0.97); the mean 100 μg PBR was 3.32 (±1.33); and the mean 150 μg PBR was 3.38 (±0.87). The mean PBR of the dye-only control was 2.22 (±1.02), significantly less than the 150 μg arm (p-value 0.008). The present study demonstrates the ability of fluorescent anti-MUC5AC antibodies to specifically target and label colonic polyps containing high-grade dysplasia and intramucosal adenocarcinoma in CPC-APC mice. This technology can potentially improve the detection rate and decrease the miss rate of advanced colonic neoplasia and early cancer at colonoscopy.

Biotinylated Fluorescent Polymeric Nanoparticles for Enhanced Immunostaining

The performance of fluorescence immunostaining is physically limited by the brightness of organic dyes, whereas fluorescence labeling with multiple dyes per antibody can lead to dye self-quenching. The present work reports a methodology of antibody labeling by biotinylated zwitterionic dye-loaded polymeric nanoparticles (NPs). A rationally designed hydrophobic polymer, poly(ethyl methacrylate) bearing charged, zwitterionic and biotin groups (PEMA-ZI-biotin), enables preparation of small (14 nm) and bright fluorescent biotinylated NPs loaded with large quantities of cationic rhodamine dye with bulky hydrophobic counterion (fluorinated tetraphenylborate). The biotin exposure at the particle surface is confirmed by Förster resonance energy transfer with dye-streptavidin conjugate. Single-particle microscopy validates specific binding to biotinylated surfaces, with particle brightness 21-fold higher than quantum dot-585 (QD-585) at 550 nm excitation. The nanoimmunostaining method, which couples biotinylated antibody (cetuximab) with bright biotinylated zwitterionic NPs through streptavidin, significantly improves fluorescence imaging of target epidermal growth factor receptors (EGFR) on the cell surface compared to a dye-based labeling. Importantly, cetuximab labeled with PEMA-ZI-biotin NPs can differentiate cells with distinct expression levels of EGFR cancer marker. The developed nanoprobes can greatly amplify the signal from labeled antibodies, and thus become a useful tool in the high-sensitivity detection of disease biomarkers.

Innovative Imaging Techniques Used to Evaluate Borderline-Resectable Pancreatic Adenocarcinoma

A diagnosis of pancreatic cancer carries a 5-y survival rate of less than 10%. Furthermore, the detection of pancreatic cancer occurs most often in later stages of the disease due to its location in the retroperitoneum and lack of symptoms (in most cases) until tumors become more advanced. Once diagnosed, cross-sectional imaging techniques are heavily utilized to determine the tumor stage and the potential for surgical resection. However, a major determinant of resectability is the extent of local vascular involvement of the mesenteric vessels and critical tributaries; current imaging techniques have limited capacity to accurately determine vascular involvement. Surrounding inflammation and fibrosis can be difficult to discriminate from viable tumor, making determination of the degree of vascular involvement unreliable. New innovations in fluorescence and optoacoustic imaging techniques may overcome these limitations and make determination of resectability more accurate. These imaging modalities are able to more clearly discern between viable tumor tissue and non-neoplastic inflammation or desmoplasia, allowing clinicians to more reliably characterize vascular involvement and develop individualized treatment plans for patients. This review will discuss the current imaging techniques used to diagnose pancreatic cancer, the barriers that current techniques raise to accurate staging, and novel fluorescence and optoacoustic imaging techniques that may provide more accurate clinical staging of pancreatic cancer.

Near-Infrared Fluorescence Imaging of Pancreatic Cancer Using a Fluorescently Labelled Anti-CEA Nanobody Probe: A Preclinical Study

Molecular fluorescence-guided surgery using near-infrared light has the potential to improve the rate of complete resection of cancer. Typically, monoclonal antibodies are being used as targeting moieties, however smaller fragments, such as single-domain antibodies (i.e., Nanobodies®) improve tumor specificity and enable tracer injection on the same day as surgery. In this study, the feasibility of a carcinoembryonic antigen-targeting Nanobody (NbCEA5) conjugated to two zwitterionic dyes (ZW800-1 Forte [ZW800F] and ZW800-1) for visualization of pancreatic ductal adenocarcinoma (PDAC) was investigated. After site-specific conjugation of NbCEA5 to the zwitterionic dyes, binding specificity was evaluated on human PDAC cell lines with flow cytometry. A dose escalation study was performed for both NbCEA5-ZW800F and NbCEA5-ZW800-1 in mice with subcutaneously implanted pancreatic tumors. Fluorescence imaging was performed up to 24 h after intravenous injection. Furthermore, the optimal dose for NbCEA5-ZW800-1 was injected in mice with orthotopically implanted pancreatic tumors. A dose-escalation study showed superior mean fluorescence intensities for NbCEA5-ZW800-1 compared to NbCEA5-ZW800F. In the orthotopic tumor models, NbCEA5-ZW800-1 accumulated specifically in pancreatic tumors with a mean in vivo tumor-to-background ratio of 2.4 (SD = 0.23). This study demonstrated the feasibility and potential advantages of using a CEA-targeted Nanobody conjugated to ZW800-1 for intraoperative PDAC imaging.

Prediction of Biomarker Expression on Primary Pancreatic Ductal Adenocarcinoma Tissues Using Fine-Needle Biopsies: Paving the Way for a Patient-Tailored Molecular Imaging Approach

BACKGROUND

Targeted molecular imaging may improve tumor cell identification during diagnosis and resection of pancreatic ductal adenocarcinoma (PDAC). Although many molecular imaging biomarkers are (over)expressed in PDAC, intertumoral heterogeneity of biomarker expression hampers universal tracer administration. Preoperative, patient-specific screening and selection of the most optimal biomarker could therefore improve tumor delineation.

OBJECTIVE

This study evaluated whether fine-needle biopsy (FNB) specimens could be used to preoperatively predict biomarker expression in the corresponding primary PDAC specimen.

METHODS

Expression of previously identified PDAC biomarkers α_vβ₆, CEACAM5, EGFR, mesothelin, Le^a/c/x, and sdi-Le^a on FNB and corresponding primary tumor (PT) specimens (n = 45) was evaluated using immunohistochemistry and quantified using a semi-automated image analysis workflow.

RESULTS

Biomarker expression on FNB and PT tissues showed high concordance (∆H-score ≤ 50), i.e. was present in 62% of cases for α_vβ₆, 61% for CEACAM5, 85% for EGFR, 69% for mesothelin, 76% for Le^a/c/x, and 79% for sdi-Le^a, indicating high concordance. Except for α_vβ₆, biomarker expression on FNB tissues was positively correlated with PT expression for all biomarkers. Subgroup analyses showed that neoadjuvant therapy (NAT) had no major and/or significant effect on concordance, expression difference and, except for mesothelin, correlation of biomarker expression between FNB and PT tissues.

CONCLUSION

This study demonstrated that biomarker expression in FNB tissues is predictive for PT expression, irrespective of the application of NAT. These findings thereby provide the foundation for the clinical application of an FNB-based biomarker-screening workflow, eventually facilitating a patient-specific approach of molecular imaging tracer administration in PDAC.

Consensus Statement on the Use of Near-Infrared Fluorescence Imaging during Pancreatic Cancer Surgery Based on a Delphi Study: Surgeons' Perspectives on Current Use and Future Recommendations

Indocyanine green (ICG) is one of the only clinically approved near-infrared (NIR) fluorophores used during fluorescence-guided surgery (FGS), but it lacks tumor specificity for pancreatic ductal adenocarcinoma (PDAC). Several tumor-targeted fluorescent probes have been evaluated in PDAC patients, yet no uniformity or consensus exists among the surgical community on the current and future needs of FGS during PDAC surgery. In this first-published consensus report on FGS for PDAC, expert opinions were gathered on current use and future recommendations from surgeons' perspectives. A Delphi survey was conducted among international FGS experts via Google Forms. Experts were asked to anonymously vote on 76 statements, with ≥70% agreement considered consensus and ≥80% participation/statement considered vote robustness. Consensus was reached for 61/76 statements. All statements were considered robust. All experts agreed that FGS is safe with few drawbacks during PDAC surgery, but that it should not yet be implemented routinely for tumor identification due to a lack of PDAC-specific NIR tracers and insufficient evidence proving FGS's benefit over standard methods. However, aside from tumor imaging, surgeons suggest they would benefit from visualizing vasculature and surrounding anatomy with ICG during PDAC surgery. Future research could also benefit from identifying neuroendocrine tumors. More research focusing on standardization and combining tumor identification and vital-structure imaging would greatly improve FGS's use during PDAC surgery.

Carcinoembryonic Antigen-Related Cell Adhesion Molecule Type 5 Receptor-Targeted Fluorescent Intraoperative Molecular Imaging Tracer for Lung Cancer: A Nonrandomized Controlled Trial

Importance

Localization of subcentimeter ground glass opacities during minimally invasive thoracoscopic lung cancer resections is a significant challenge in thoracic oncology. Intraoperative molecular imaging has emerged as a potential solution, but the availability of suitable fluorescence agents is a limiting factor.

Objective

To evaluate the suitability of SGM-101, a carcinoembryonic antigen-related cell adhesion molecule type 5 (CEACAM5) receptor-targeted near-infrared fluorochrome, for molecular imaging-guided lung cancer resections, because glycoprotein is expressed in more than 80% of adenocarcinomas.

Design, Setting, and Participants

For this nonrandomized, proof-of-principal, phase 1 controlled trial, patients were divided into 2 groups between August 1, 2020, and January 31, 2022. Patients with known CEACAM5-positive gastrointestinal tumors suggestive of lung metastasis were selected as proof-of-principle positive controls. The investigative group included patients with lung nodules suggestive of primary lung malignant neoplasms. Patients 18 years or older without significant comorbidities that precluded surgical exploration with suspicious pulmonary nodules requiring surgical biopsy were included in the study.

Interventions

SGM-101 (10 mg) was infused up to 5 days before index operation, and pulmonary nodules were imaged using a near-infrared camera system with a dedicated thoracoscope.

Main Outcomes and Measures

SGM-101 localization to pulmonary nodules and its correlation with CEACAM5 glycoprotein expression by the tumor as quantified by tumor and normal pulmonary parenchymal fluorescence.

Results

Ten patients (5 per group; 5 male and 5 female; median [IQR] age, 66 [58-69] years) with 14 total lesions (median [range] lesion size, 0.91 [0.90-2.00] cm) were enrolled in the study. In the control group of 4 patients (1 patient did not undergo surgical resection because of abnormal preoperative cardiac clearance findings that were not deemed related to SGM-101 infusion), the mean (SD) lesion size was 1.33 (0.48) cm, 2 patients had elevated serum CEA markers, and 2 patients had normal serum CEA levels. Of the 4 patients who underwent surgical intervention, those with 2+ and 3+ tissue CEACAM5 expression had excellent tumor fluorescence, with a mean (SD) tumor to background ratio of 3.11 (0.45). In the patient cohort, the mean (SD) lesion size was 0.68 (0.22) cm, and no elevations in serum CEA levels were found. Lack of SGM-101 fluorescence was associated with benign lesions and with lack of CEACAM5 staining.

Conclusions and Relevance

This in-human proof-of-principle nonrandomized controlled trial demonstrated SGM-101 localization to CEACAM5-positive tumors with the detection of real-time near-infrared fluorescence in situ, ex vivo, and by immunofluorescence microscopy. These findings suggest that SGM-101 is a safe, receptor-specific, and feasible intraoperative molecular imaging fluorochrome that should be further evaluated in randomized clinical trials.

Trial Registration

ClinicalTrials.gov identifier: NCT04315467.

Use of Freshly Amputated Human Limbs for Pre-Clinical Evaluation of Molecular-Targeted Fluorescent Probes

We have co-developed a first-in-kind model of fluorophore testing in freshly amputated human limbs. Ex vivo human tissue provides a unique opportunity for the testing of pre-clinical fluorescent agents, collection of imaging data, and histopathologic examination in human tissue prior to performing in vivo experiments. Existing pre-clinical fluorescent agent studies rely primarily on animal models, which do not directly predict fluorophore performance in humans and can result in wasted resources and time if an agent proves ineffective in early human trials. Because fluorophores have no desired therapeutic effect, their clinical utility is based solely on their safety and ability to highlight tissues of interest. Advancing to human trials even via the FDA's phase 0/microdose pathway still requires substantial resources, single-species pharmacokinetic testing, and toxicity testing. In a recently concluded study using amputated human lower limbs, we were able to test successfully a nerve-specific fluorophore in pre-clinical development. This study used systemic administration via vascular cannulization and a cardiac perfusion pump. We envision that this model may assist with early lead agent testing selection for fluorophores with various targets and mechanisms.

Intraoperative Molecular Fluorescence Imaging of Pancreatic Cancer by Targeting Vascular Endothelial Growth Factor: A Multicenter Feasibility Dose-Escalation Study

Tumor visualization with near-infrared fluorescence (NIRF) imaging might aid exploration and resection of pancreatic cancer by visualizing the tumor in real time. Conjugation of the near-infrared fluorophore IRDye800CW to the monoclonal antibody bevacizumab enables targeting of vascular endothelial growth factor A. The aim of this study was to determine whether intraoperative tumor-specific imaging of pancreatic cancer with the fluorescent tracer bevacizumab-800CW is feasible and safe. Methods: In this multicenter dose-escalation phase I trial, patients in whom pancreatic ductal adenocarcinoma (PDAC) was suspected were administered bevacizumab-800CW (4.5, 10, or 25 mg) 3 d before surgery. Safety monitoring encompassed allergic or anaphylactic reactions and serious adverse events attributed to bevacizumab-800CW. Intraoperative NIRF imaging was performed immediately after laparotomy, just before and after resection of the specimen. Postoperatively, fluorescence signals on the axial slices and formalin-fixed paraffin-embedded tissue blocks from the resected specimens were correlated with histology. Subsequently, tumor-to-background ratios (TBR) were calculated. Results: Ten patients with clinically suspected PDAC were enrolled in the study. Four of the resected specimens were confirmed PDACs; other malignancies were distal cholangiocarcinoma, ampullary carcinoma, and neuroendocrine tumors. No serious adverse events were related to bevacizumab-800CW. In vivo tumor visualization with NIRF imaging differed per tumor type and was nonconclusive. Ex vivo TBRs were 1.3, 1.5, and 2.5 for the 4.5-, 10-, and 25-mg groups, respectively. Conclusion: NIRF-guided surgery in patients with suspected PDAC using bevacizumab-IRDye800CW is feasible and safe. However, suboptimal TBRs were obtained because no clear distinction between pancreatic cancer from normal or inflamed pancreatic tissue was achieved. Therefore, a more tumor-specific tracer than bevacizumab-IRDye800CW for PDAC is preferred.

Fluorescence probes for lung carcinoma diagnosis and clinical application

This review provides an overview of the most recent developments in fluorescence probe technology for the accurate detection and clinical therapy of lung carcinoma.

Design and selection of optimal ErbB-targeting bispecific antibodies in pancreatic cancer

The ErbB family of receptor tyrosine kinases is a primary target for small molecules and antibodies for pancreatic cancer treatment. Nonetheless, the current treatments for this tumor are not optimal due to lack of efficacy, resistance, or toxicity. Here, using the novel BiXAb™ tetravalent format platform, we generated bispecific antibodies against EGFR, HER2, or HER3 by considering rational epitope combinations. We then screened these bispecific antibodies and compared them with the parental single antibodies and antibody pair combinations. The screen readouts included measuring binding to the cognate receptors (mono and bispecificity), intracellular phosphorylation signaling, cell proliferation, apoptosis and receptor expression, and also immune system engagement assays (antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity). Among the 30 BiXAbs™ tested, we selected 3Patri-1Cetu-Fc, 3Patri-1Matu-Fc and 3Patri-2Trastu-Fc as lead candidates. The in vivo testing of these three highly efficient bispecific antibodies against EGFR and HER2 or HER3 in pre-clinical mouse models of pancreatic cancer showed deep antibody penetration in these dense tumors and robust tumor growth reduction. Application of such semi-rational/semi-empirical approach, which includes various immunological assays to compare pre-selected antibodies and their combinations with bispecific antibodies, represents the first attempt to identify potent bispecific antibodies against ErbB family members in pancreatic cancer.

Factors for Differential Outcome Across Cancers in Clinical Molecule-Targeted Fluorescence Imaging

Clinical imaging performance using a fluorescent antibody was compared across 3 cancers to elucidate physical and biologic factors contributing to differential translation of epidermal growth factor receptor (EGFR) expression to macroscopic fluorescence in tumors. Methods: Thirty-one patients with high-grade glioma (HGG, n = 5), head-and-neck squamous cell carcinoma (HNSCC, n = 23), or lung adenocarcinoma (LAC, n = 3) were systemically infused with 50 mg of panitumumab-IRDye800 1-3 d before surgery. Intraoperative open-field fluorescent images of the surgical field were acquired, with imaging device settings and operating room lighting conditions being tested on tissue-mimicking phantoms. Fluorescence contrast and margin size were measured on resected specimen surfaces. Antibody distribution and EGFR immunoreactivity were characterized in macroscopic and microscopic histologic structures. The integrity of the blood-brain barrier was examined via tight junction protein (Claudin-5) expression with immunohistochemistry. Stepwise multivariate linear regression of biologic variables was performed to identify independent predictors of panitumumab-IRDye800 concentration in tissue. Results: Optimally acquired at the lowest gain for tumor detection with ambient light, intraoperative fluorescence imaging enhanced tissue-size dependent tumor contrast by 5.2-fold, 3.4-fold, and 1.4-fold in HGG, HNSCC, and LAC, respectively. Tissue surface fluorescence target-to-background ratio correlated with margin size and identified 78%-97% of at-risk resection margins ex vivo. In 4-μm-thick tissue sections, fluorescence detected tumor with 0.85-0.89 areas under the receiver-operating-characteristic curves. Preferential breakdown of blood-brain barrier in HGG improved tumor specificity of intratumoral antibody distribution relative to that of EGFR (96% vs. 80%) despite its reduced concentration (3.9 ng/mg of tissue) compared with HNSCC (8.1 ng/mg) and LAC (6.3 ng/mg). Cellular EGFR expression, tumor cell density, plasma antibody concentration, and delivery barrier were independently associated with local intratumoral panitumumab-IRDye800 concentration, with 0.62 goodness of fit of prediction. Conclusion: In multicancer clinical imaging of a receptor-ligand-based molecular probe, plasma antibody concentration, delivery barrier, and intratumoral EGFR expression driven by cellular biomarker expression and tumor cell density led to heterogeneous intratumoral antibody accumulation and spatial distribution whereas tumor size, resection margin, and intraoperative imaging settings substantially influenced macroscopic tumor contrast.

Preclinical Evaluation of a Humanized, Near-Infrared Fluorescent Antibody for Fluorescence-Guided Surgery of MUC16-Expressing Pancreatic Cancer

Surgery remains the only potentially curative treatment option for pancreatic cancer, but resections are made more difficult by infiltrative disease, proximity of critical vasculature, peritumoral inflammation, and dense stroma. Surgeons are limited to tactile and visual cues to differentiate cancerous tissue from normal tissue. Furthermore, translating preoperative images to the intraoperative setting poses additional challenges for tumor detection, and can result in undetected and unresected lesions. Thus, pancreatic ductal adenocarcinoma (PDAC) has high rates of incomplete resections, and subsequently, disease recurrence. Fluorescence-guided surgery (FGS) has emerged as a method to improve intraoperative detection of cancer and ultimately improve surgical outcomes. Initial clinical trials have demonstrated feasibility of FGS for PDAC, but there are limited targeted probes under investigation for this disease, highlighting the need for development of additional novel biomarkers to reflect the PDAC heterogeneity. MUCIN16 (MUC16) is a glycoprotein that is overexpressed in 60-80% of PDAC. In our previous work, we developed a MUC16-targeted murine antibody near-infrared conjugate, termed AR9.6-IRDye800, that showed efficacy in detecting pancreatic cancer. To build on the translational potential of this imaging probe, a humanized variant of the AR9.6 fluorescent conjugate was developed and investigated herein. This conjugate, termed huAR9.6-IRDye800, showed equivalent binding properties to its murine counterpart. Using an optimized dye:protein ratio of 1:1, in vivo studies demonstrated high tumor to background ratios in MUC16-expressing tumor models, and delineation of tumors in a patient-derived xenograft model. Safety, biodistribution, and toxicity studies were conducted. These studies demonstrated that huAR9.6-IRDye800 was safe, did not yield evidence of histological toxicity, and was well tolerated in vivo. The results from this work suggest that AR9.6-IRDye800 is an efficacious and safe imaging agent for identifying pancreatic cancer intraoperatively through fluorescence-guided surgery.

The current status and future prospects for molecular imaging-guided precision surgery

Molecular imaging technologies are increasingly used to diagnose, monitor, and guide treatment of i.e., cancer. In this review, the current status and future prospects of the use of molecular imaging as an instrument to help realize precision surgery is addressed with focus on the main components that form the conceptual basis of intraoperative molecular imaging. Paramount for successful interventions is the relevance and accessibility of surgical targets. In addition, selection of the correct combination of imaging agents and modalities is critical to visualize both microscopic and bulk disease sites with high affinity and specificity. In this context developments within engineering/imaging physics continue to drive the growth of image-guided surgery. Particularly important herein is enhancement of sensitivity through improved contrast and spatial resolution, features that are critical if sites of cancer involvement are not to be overlooked during surgery. By facilitating the connection between surgical planning and surgical execution, digital surgery technologies such as computer-aided visualization nicely complement these technologies. The complexity of image guidance, combined with the plurality of technologies that are becoming available, also drives the need for evaluation mechanisms that can objectively score the impact that technologies exert on the performance of healthcare professionals and outcome improvement for patients.

Label-free differentiation of human pancreatic cancer, pancreatitis, and normal pancreatic tissue by molecular spectroscopy

SIGNIFICANCE

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer deaths with a best median survival of only 40 to 50 months for localized disease despite multimodal treatment. The standard tissue differentiation method continues to be pathology with histological staining analysis. Microscopic discrimination between inflammatory pancreatitis and malignancies is demanding.

AIM

We aim to accurately distinguish native pancreatic tissue using infrared (IR) spectroscopy in a fast and label-free manner.

APPROACH

Twenty cryopreserved human pancreatic tissue samples were collected from surgical resections. In total, more than 980,000 IR spectra were collected and analyzed using aMATLAB package. For differentiation of PDAC, pancreatitis, and normal tissue, a three-class training set for supervised classification was created with 25,000 spectra and the principal component analysis (PCA) score values for each cohort. Cross-validation was performed using the leaveone- out method. Validation of the algorithm was accomplished with 13 independent test samples.

RESULTS

Reclassification of the training set and the independent test samples revealed an overall accuracy of more than 90% using a discrimination algorithm.

CONCLUSION

IR spectroscopy in combination with PCA and supervised classification is an efficient analytical method to reliably distinguish between benign and malignant pancreatic tissues. It opens up a wide research field for oncological and surgical applications.

Antibody-Based Approaches to Target Pancreatic Tumours

Pancreatic cancer is an aggressive cancer with a dismal prognosis. This is due to the difficulty to detect the disease at an early and curable stage. In addition, only limited treatment options are available, and they are confronted by mechanisms of resistance. Monoclonal antibody (mAb) molecules are highly specific biologics that can be directly used as a blocking agent or modified to deliver a drug payload depending on the desired outcome. They are widely used to target extracellular proteins, but they can also be employed to inhibit intracellular proteins, such as oncoproteins. While mAbs are a class of therapeutics that have been successfully employed to treat many cancers, they have shown only limited efficacy in pancreatic cancer as a monotherapy so far. In this review, we will discuss the challenges, opportunities and hopes to use mAbs for pancreatic cancer treatment, diagnostics and imagery.

Fluorescent Anti-CEA Nanobody for Rapid Tumor-Targeting and Imaging in Mouse Models of Pancreatic Cancer

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.

Novel fluorescent GLUT1 inhibitor for precision detection and fluorescence image-guided surgery in oral squamous cell carcinoma

Early detection and complete resection of oral squamous cell carcinoma (OSCC) are crucial to improving patient survival and prognosis. However, specifically targeted imaging probes for OSCC detection are limited. This study aimed to synthesize a novel near-infrared fluorescence (NIRF) probe for precision detection and fluorescence image-guided surgery in OSCC. Bioinformatics data indicated that glucose transporter 1 (GLUT1) is highly expressed in patients with OSCC. We demonstrated high and specific GLUT1 expression upon immunohistochemical staining of samples from 20 patients with OSCC. The specific expression of GLUT1 was further validated in both human OSCC cell lines and OSCC tumor xenografts. Based on these findings, the GLUT1 inhibitor WZB117 was utilized to synthesize a novel NIRF imaging probe, WZB117-IR820. The fluorescence molecular imaging data revealed that WZB117-IR820 could specifically bind to the tumor areas in an orthotopic OSCC mouse model after intravenous injection and could be further applied for precision fluorescence image-guided surgery with no residual tumor in the orthotopic CAL27-fLUC mouse tumor model. For further clinical translational application in patients with OSCC, precise delineation of OSCC tumor areas was achieved following topical application of the WZB117-IR820 imaging probe and was validated by histopathological and immunohistochemical analyses. In conclusion, we synthesized a novel fluorescent imaging probe, WZB117-IR820, which has potential clinical applications for early detection and fluorescence image-guided surgery in OSCC with no observable toxicity. This article is protected by copyright. All rights reserved.

Near-Infrared Fluorescence Imaging of EGFR-Overexpressing Tumors in the Mouse Xenograft Model Using scFv-IRDye800CW and Cetuximab-IRDye800CW

EGFR (epidermal growth factor receptor) is overexpressed in a variety of human cancers (including squamous cell carcinoma of head and neck, colon cancer, and some breast cancers) and therefore is regarded as an ideal target for cancer therapy or imaging purposes. In the current study, we produced a scFv-based near-infrared probe (called cet.Hum.scFv-IRDye-800CW) and evaluated its ability in recognizing and imaging of EGFR-overexpressing tumors in a mouse model. Like the molecular probe consisting of its parental antibody (cetuximab, an FDA-approved monoclonal antibody) and IRD800CW, cet.Hum.scFv-IRDye-800CW was able to recognize EGFR-overexpressing tumors in mice. cet.Hum.scFv-IRDye-800CW was found to be superior to the cetuximab-based probe in imaging of mouse tumors. The tumor-to-background ratio and blood clearance rate were higher when cet.Hum.scFv-IRDye-800CW was used as an imaging probe.

Recent development of a magneto-optical nanoplatform for multimodality imaging of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. Given its inconspicuous and atypical early symptoms and hidden location, most patients have already reached the terminal stage before diagnosis. At present, the diagnosis of PDAC mainly depends on serological and imaging examinations. However, serum tests cannot identify specific tumor locations and each imaging technology has its own defects, bringing great challenges to the early diagnosis of PDAC. Therefore, it is of great significance to find new strategies for the early and accurate diagnosis of PDAC. In recent years, a magneto-optical nanoplatform integrating near infrared fluorescence, photoacoustic, magnetic resonance imaging, etc. has attracted widespread attention, giving full play to the complementary advantages of each imaging modality. Herein, we summarize the recent advances of imaging modalities in the diagnosis of pancreatic cancer, and then discuss in detail the construction and modification of magneto or/and optical probes for multimodal imaging, and advances in early diagnosis using the combination of various imaging modalities, which can provide potential tools for the early diagnosis or even intraoperative navigation and post-treatment follow-up of PDAC patients.

Fluorescent imaging for cancer therapy and cancer gene therapy

The translation of laboratory science into effective clinical cancer therapy is gaining momentum more rapidly than any other time in history. Understanding cancer cell-surface receptors, cancer cell growth, and cancer metabolic pathways has led to many promising molecular-targeted therapies and cancer gene therapies. These same targets may also be exploited for optical imaging of cancer. Theoretically, any antibody or small molecule targeting cancer can be labeled with bioluminescent or fluorescent agents. In the laboratory setting, fluorescence imaging (FI) and bioluminescence imaging (BLI) have long been used in preclinical research for quantification of tumor bulk, assessment of targeting of tumors by experimental agents, and discrimination between primary and secondary effects of cancer treatments. Many of these laboratory techniques are now moving to clinical trials. Imageable engineered fluorescent probes that are highly specific for cancer are being advanced. This will allow for the identification of tumors for staging, tracking novel therapeutic agents, assisting in adequate surgical resection, and allowing image-guided biopsies. The critical components of FI include (1) a fluorescent protein that is biologically safe, stable, and distinctly visible with a high target to background ratio and (2) highly sensitive optical detectors. This review will summarize the most promising optical imaging agents and detection devices for cancer clinical research and clinical care.

Overview and Future Perspectives on Tumor-Targeted Positron Emission Tomography and Fluorescence Imaging of Pancreatic Cancer in the Era of Neoadjuvant Therapy

BACKGROUND

Despite recent advances in the multimodal treatment of pancreatic ductal adenocarcinoma (PDAC), overall survival remains poor with a 5-year cumulative survival of approximately 10%. Neoadjuvant (chemo- and/or radio-) therapy is increasingly incorporated in treatment strategies for patients with (borderline) resectable and locally advanced disease. Neoadjuvant therapy aims to improve radical resection rates by reducing tumor mass and (partial) encasement of important vascular structures, as well as eradicating occult micrometastases. Results from recent multicenter clinical trials evaluating this approach demonstrate prolonged survival and increased complete surgical resection rates (R0). Currently, tumor response to neoadjuvant therapy is monitored using computed tomography (CT) following the RECIST 1.1 criteria. Accurate assessment of neoadjuvant treatment response and tumor resectability is considered a major challenge, as current conventional imaging modalities provide limited accuracy and specificity for discrimination between necrosis, fibrosis, and remaining vital tumor tissue. As a consequence, resections with tumor-positive margins and subsequent early locoregional tumor recurrences are observed in a substantial number of patients following surgical resection with curative intent. Of these patients, up to 80% are diagnosed with recurrent disease after a median disease-free interval of merely 8 months. These numbers underline the urgent need to improve imaging modalities for more accurate assessment of therapy response and subsequent re-staging of disease, thereby aiming to optimize individual patient's treatment strategy. In cases of curative intent resection, additional intra-operative real-time guidance could aid surgeons during complex procedures and potentially reduce the rate of incomplete resections and early (locoregional) tumor recurrences. In recent years intraoperative imaging in cancer has made a shift towards tumor-specific molecular targeting. Several important molecular targets have been identified that show overexpression in PDAC, for example: CA19.9, CEA, EGFR, VEGFR/VEGF-A, uPA/uPAR, and various integrins. Tumor-targeted PET/CT combined with intraoperative fluorescence imaging, could provide valuable information for tumor detection and staging, therapy response evaluation with re-staging of disease and intraoperative guidance during surgical resection of PDAC.

METHODS

A literature search in the PubMed database and (inter)national trial registers was conducted, focusing on studies published over the last 15 years. Data and information of eligible articles regarding PET/CT as well as fluorescence imaging in PDAC were reviewed. Areas covered: This review covers the current strategies, obstacles, challenges, and developments in targeted tumor imaging, focusing on the feasibility and value of PET/CT and fluorescence imaging for integration in the work-up and treatment of PDAC. An overview is given of identified targets and their characteristics, as well as the available literature of conducted and ongoing clinical and preclinical trials evaluating PDAC-targeted nuclear and fluorescent tracers.

The Use of Fluorescent Anti-CEA Antibodies to Label, Resect and Treat Cancers: A Review

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.

Targeted optical fluorescence imaging: a meta-narrative review and future perspectives

Purpose

The aim of this review is to give an overview of the current status of targeted optical fluorescence imaging in the field of oncology, cardiovascular, infectious and inflammatory diseases to further promote clinical translation.

Methods

A meta-narrative approach was taken to systematically describe the relevant literature. Consecutively, each field was assigned a developmental stage regarding the clinical implementation of optical fluorescence imaging.

Results

Optical fluorescence imaging is leaning towards clinical implementation in gastrointestinal and head and neck cancers, closely followed by pulmonary, neuro, breast and gynaecological oncology. In cardiovascular and infectious disease, optical imaging is in a less advanced/proof of concept stage.

Conclusion

Targeted optical fluorescence imaging is rapidly evolving and expanding into the clinic, especially in the field of oncology. However, the imaging modality still has to overcome some major challenges before it can be part of the standard of care in the clinic, such as the provision of pivotal trial data. Intensive multidisciplinary (pre-)clinical joined forces are essential to overcome the delivery of such compelling phase III registration trial data and subsequent regulatory approval and reimbursement hurdles to advance clinical implementation of targeted optical fluorescence imaging as part of standard practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05504-y.

Development and Characterisation of Antibody-Based Optical Imaging Probes for Inflammatory Bowel Disease

Monoclonal antibodies are an important addition to the medicinal treatment paradigm for IBD patients. While effective, these agents show a high degree of primary and secondary non-response, and methods to predict response are highly desired. Information on drug distribution at the target level is often lacking. Fluorescent endoscopic imaging using labelled antibody drugs may provide insight regarding drug distribution, target engagement and drug response, but these assessments require stable and functional fluorescently-conjugated probes. Infliximab, vedolizumab, adalimumab and ustekinumab were conjugated to IRDye 800CW, IRDye 680LT and ZW800-1. The resulting 12 tracer candidates were analysed and characterised on SE-HPLC, SDS-PAGE, iso-electric focussing (IEF) and ELISA in order to evaluate their feasibility as candidate clinical tracers for cGMP development. Major differences in the conjugation results could be seen for each conjugated drug. For Infliximab, 2 conjugates (800CW and 680LT) showed formation of aggregates, while conjugates of all drugs with ZW800-1 showed reduced fluorescent brightness, reduced purification yield and formation of fragments. All 6 of these candidates were considered unfeasible. From the remaining 6, ustekinumab-680LT showed reduced binding to IL23, and was therefore considered unfeasible. Out of 12 potential tracer candidates, 5 were considered feasible for further development: vedolizumab-800CW, vedolizumab-680LT, adalimumab-800CW, adalimumab-680LT and ustekinumab-800CW. Infliximab-680LT and ustekinumab-680LT failed to meet the standards for this panel, but may be rendered feasible if tracer production methods were further optimized.