Characterizing the Utility and Limitations of Repurposing an Open-Field Optical Imaging Device for Fluorescence-Guided Surgery in Head and Neck Cancer Patients

Identification of Optimal Tissue-Marking Dye Color for Pathological Evaluation in Fluorescence Imaging Using IRDye800CW

PURPOSE

Fluorescence-guided surgery using a tumor-specific antibody-dye conjugate is useful in various cancer types. Fluorescence imaging is a valuable tool both intraoperatively and postoperatively for ex vivo imaging. The color of inks used for tumor specimens during ex vivo specimen processing in pathology is an important consideration for fluorescence imaging since the absorption/emission of the dyes may interfere with the fluorescent dye. This study assesses suitable ink colors for use specifically with IRDye800CW fluorescence imaging.

PROCEDURES

Eight tissue-marking inks or dyes (TMDs) commonly used for pathological evaluation were assessed. Agarose tissue-mimicking phantoms containing Panitumumab-IRDye800CW were used as an initial model. Mean fluorescence intensity was measured at 800 nm using both Pearl Trilogy as a closed-field fluorescence imaging system and pde-neo II as an open-field fluorescence imaging system before and after TMD application. An in vivo mouse xenograft model using the human head and neck squamous cell carcinoma FaDu cell line was then used in conjunction with TMDs.

RESULTS

The retained IRDye800CW fluorescence on Pearl Trilogy was as follows: yellow at 91.0 ± 4.5%, red at 90.6 ± 2.7%, orange at 88.2 ± 2.2%, violet at 56.6 ± 1.1%, lime at 40.9 ± 1.8%, green at 19.3 ± 2.8%, black at 13.3 ± 0.6%, and blue at 8.1 ± 0.2%. The retained IRDye800CW fluorescence on pde-neo II was as follows: yellow at 86.5 ± 6.4%, red at 77.0 ± 6.2%, orange at 76.9 ± 2.8%, lime at 72.5 ± 9.5%, violet at 59.7 ± 0.4%, green at 30.1 ± 6.9%, black at 17.0 ± 2.7%, and blue at 6.7 ± 1.7%. The retained IRDye800CW fluorescence in yellow and blue TMDs was 42.1 ± 14.9% and 0.2 ± 0.2%, respectively in the mouse experiment (p = 0.039).

CONCLUSION

Yellow, red, and orange TMDs should be used, and blue and black TMDs should be avoided for evaluating tumor specimens through fluorescence imaging using IRDye800CW.

Preclinical assessment of IRDye800CW-labeled gastrin-releasing peptide receptor-targeting peptide for near infrared-II imaging of brain malignancies

We aimed to develop a new biocompatible gastrin-releasing peptide receptor (GRPR) targeted optical probe, IRDye800-RM26, for fluorescence image-guided surgery (FGS) of brain malignancies in near-infrared window II (NIR-II) imaging. We developed a novel GRPR targeting probe using a nine-amino-acid bombesin antagonist analog RM26 combined with IRDye800CW, and explored the fluorescent probe according to optical properties. Fluorescence imaging characterization in NIR-I/II region was performed in vitro and in vivo. Following simulated NIR-II image-guided surgery, we obtained time-fluorescent intensity curves and time-signal and background ratio curves. Further, we used histological sections of brain from tumor-beating mice model to compare imaging specificity between 5-aminolevulinic acid (5-ALA) and IRDye800-RM26, and evaluated biodistribution and biocompatibility. IRDye800-RM26 had broad emission ranging from 800 to 1200 nm, showing considerable fluorescent intensity in NIR-II region. High-resolution NIR-II imaging of IRDye800-RM26 can enhance the advantages of NIR-I imaging. Dynamic and real time fluorescence imaging in NIR-II region showed that the probe can be used to treat brain malignancies in mice between 12 and 24 h post injection. Its specificity in targeting glioblastoma was superior to 5-ALA. Biodistribution analysis indicated IRDye800-RM26 excretion in the kidney and liver. Histological and blood test analyses did not reveal acute severe toxicities in mice treated with effective dose (40 μg) of the probe for NIR-II imaging. Because of the considerable fluorescent intensity in NIR-II region and high spatial resolution, biocompatible and excretable IRDye800-RM26 holds great potentials for FGS, and is essential for translation into human use.

Fluorescence guidance improves the accuracy of radiological imaging-guided surgical navigation

BACKGROUND

Imaging-based navigation technologies require static referencing between the target anatomy and the optical sensors. Imaging-based navigation is therefore well suited to operations involving bony anatomy; however, these technologies have not translated to soft-tissue surgery. We sought to determine if fluorescence imaging complement conventional, radiological imaging-based navigation to guide the dissection of soft-tissue phantom tumors.

METHODS

Using a human tissue-simulating model, we created tumor phantoms with physiologically accurate optical density and contrast concentrations. Phantoms were dissected using all possible combinations of computed tomography (CT), magnetic resonance, and fluorescence imaging; controls were included. The data were margin accuracy, margin status, tumor spatial alignment, and dissection duration.

RESULTS

Margin accuracy was higher for combined navigation modalities compared to individual navigation modalities, and accuracy was highest with combined CT and fluorescence navigation (p = 0.045). Margin status improved with combined CT and fluorescence imaging.

CONCLUSIONS

At present, imaging-based navigation has limited application in guiding soft-tissue tumor operations due to its inability to compensate for positional changes during surgery. This study indicates that fluorescence guidance enhances the accuracy of imaging-based navigation and may be best viewed as a synergistic technology, rather than a competing one.

Quantifying the Impact of Signal-to-background Ratios on Surgical Discrimination of Fluorescent Lesions

PURPOSE

Surgical fluorescence guidance has gained popularity in various settings, e.g., minimally invasive robot-assisted laparoscopic surgery. In pursuit of novel receptor-targeted tracers, the field of fluorescence-guided surgery is currently moving toward increasingly lower signal intensities. This highlights the importance of understanding the impact of low fluorescence intensities on clinical decision making. This study uses kinematics to investigate the impact of signal-to-background ratios (SBR) on surgical performance.

METHODS

Using a custom grid exercise containing hidden fluorescent targets, a da Vinci Xi robot with Firefly fluorescence endoscope and ProGrasp and Maryland forceps instruments, we studied how the participants' (N = 16) actions were influenced by the fluorescent SBR. To monitor the surgeon's actions, the surgical instrument tip was tracked using a custom video-based tracking framework. The digitized instrument tracks were then subjected to multi-parametric kinematic analysis, allowing for the isolation of various metrics (e.g., velocity, jerkiness, tortuosity). These were incorporated in scores for dexterity (Dx), decision making (DM), overall performance (PS) and proficiency. All were related to the SBR values.

RESULTS

Multi-parametric analysis showed that task completion time, time spent in fluorescence-imaging mode and total pathlength are metrics that are directly related to the SBR. Below SBR 1.5, these values substantially increased, and handling errors became more frequent. The difference in Dx and DM between the targets that gave SBR < 1.50 and SBR > 1.50, indicates that the latter group generally yields a 2.5-fold higher Dx value and a threefold higher DM value. As these values provide the basis for the PS score, proficiency could only be achieved at SBR > 1.55.

CONCLUSION

By tracking the surgical instruments we were able to, for the first time, quantitatively and objectively assess how the instrument positioning is impacted by fluorescent SBR. Our findings suggest that in ideal situations a minimum SBR of 1.5 is required to discriminate fluorescent lesions, a substantially lower value than the SBR 2 often reported in literature.

Applicability of autofluorescence and fluorescent probes in the trans-surgical of oral carcinomas: A systematic review

Oral cancer represents an important health problem, as it is the sixth most common type of cancer in the world and is associated with high rates of morbidity and mortality. The treatment considered the gold standard for this type of tumor is surgical resection with negative margins, with a distance of at least 5 mm from the tumor. This procedure is strongly associated with local control and disease-specific survival, however, in many cases, large amounts of healthy tissue are removed, resulting in surgical defects, compromising various functions and directly affecting the individual's quality of life. From this perspective, this systematic review aimed to evaluate the use of autofluorescence and fluorescent probes as potential adjuvant techniques to facilitate the delineation of surgical margins for oral cancers. A comprehensive search was performed in Pubmed, Scopus, Web of Science, LIVIVO, Embase, ProQuest Open Access Dissertations & Theses, Open Access Theses and Dissertations, and DART Europe databases, where 1948 articles were found. After the different stages of critical evaluation, 15 articles were selected, eligible for the inclusion criteria. Of these, 7 articles used autofluorescence, 7 used fluorescent probes and 1 article used both methods. As for autofluorescence, the most used device was the VELScope, and indocyanine green was the most used probe. Compared to histopathology, autofluorescence did not obtain significant and/or superiors results. In contrast to fluorescent probes that, most articles showed a good performance of margins during surgical resection, making them a promising alternative. However, it is still necessary to carry out the analysis of more articles, with more significant samples and sensitivity and specificity data to qualify the results.

Updates on fluorescent probes and open-field imaging methods for fluorescence-guided cytoreductive surgery for epithelial ovarian cancer: A review

Fluorescence-guided surgery has emerged as a promising imaging technique for real-time intraoperative tumour delineation and visualisation of submillimetre tumour masses in cytoreductive surgery for epithelial ovarian cancer (EOC). Researchers have developed several EOC-targeted fluorescent probes, most of which are currently in the preclinical stage. Interestingly, imaging devices designed for open surgery are proof of concept. This review summarises the recent advances in EOC-targeted fluorescent probes and open-field fluorescence imaging strategies and discusses the challenges and potential solutions for clinical translation.

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.

Fundamentals and developments in fluorescence-guided cancer surgery

Fluorescence-guided surgery using tumour-targeted imaging agents has emerged over the past decade as a promising and effective method of intraoperative cancer detection. An impressive number of fluorescently labelled antibodies, peptides, particles and other molecules related to cancer hallmarks have been developed for the illumination of target lesions. New approaches are being implemented to translate these imaging agents into the clinic, although only a few have made it past early-phase clinical trials. For this translational process to succeed, target selection, imaging agents and their related detection systems and clinical implementation have to operate in perfect harmony to enable real-time intraoperative visualization that can benefit patients. Herein, we review key aspects of this imaging cascade and focus on imaging approaches and methods that have helped to shed new light onto the field of intraoperative fluorescence-guided cancer surgery with the singular goal of improving patient outcomes.

Tumor-Background Ratio is an effective method to identify tumors and false-positive nodules in indocyanine-green navigation surgery for pediatric liver cancer

BACKGROUND

Indocyanine green (ICG) navigation surgery has been used for hepatoblastoma (HB) in children but the technique has been reported for using in other childhood liver cancers were rare. This article summarizes the application experience of ICG in HB and other childhood liver cancers in children and explores the role of fluorescence intensity measurement in identifying tumors.

METHODS

To summarize the clinical experience of children with liver cancer treated by ICG navigation surgery. The tumor and its surrounding tissue were photographed by near infrared during the operation. The fluorescence intensity of tumors, ICG (+) lesions and the normal liver was measured, and the Tumor-Background Ratio (TBR) was calculated.

RESULTS

A total of 11 children with liver cancer were injected intravenously with ICG 1 day before operation. With the help of ICG fluorescence navigation, there was no residual tumor at the surgical margin for all the children. Total fluorescence was seen in 2 cases, rim fluorescence in 2 cases, and partial fluorescence in 7 cases. 19 ICG false-positive nodules were found on the resection stump or residual liver tissue in 5 cases, and the TBR value of tumors was higher than that of false- positive nodules. 10 children have survived without disease.

CONCLUSION

ICG navigation surgery is safe and feasible for liver cancer in children, which can enhance the visualization of the tumor during operation and provide more information about the location and boundaries of the tumor. This technique also has limitations, which can be affected by chemotherapy, tumor location, ICG administration regimen, and equipment. TBR is an effective method to identify tumor and non-cancerous lesions.

An overview of the current clinical status of optical imaging in head and neck cancer with a focus on Narrow Band imaging and fluorescence optical imaging

Early and accurate identification of head and neck squamous cell carcinoma (HNSCC) is important to improve treatment outcomes and prognosis. New optical imaging techniques may assist in both the diagnostic process as well as in the operative setting by real-time visualization and delineation of tumor. Narrow Band Imaging (NBI) is an endoscopic technique that uses blue and green light to enhance mucosal and submucosal blood vessels, leading to better detection of (pre)malignant lesions showing aberrant blood vessel patterns. Fluorescence optical imaging makes use of near-infrared fluorescent agents to visualize and delineate HNSCC, resulting in fewer positive surgical margins. Targeted fluorescent agents, such as fluorophores conjugated to antibodies, show the most promising results. The aim of this review is: (1) to provide the clinical head and neck surgeon an overview of the current clinical status of various optical imaging techniques in head and neck cancer; (2) to provide an in-depth review of NBI and fluorescence optical imaging, as these techniques have the highest potential for clinical implementation; and (3) to describe future improvements and developments within the field of these two techniques.

Recent Developments of ICG-Guided Sentinel Lymph Node Mapping in Oral Cancer

Sentinel lymph node (SLN) biopsy has gained attention as a method of minimizing the extent of neck dissection with a similar survival rate as elective neck dissection in oral cancer. Indocyanine green (ICG) imaging is widely used in the field of surgical oncology. Real-time ICG-guided SLN imaging has been widely used in minimally invasive surgeries for various types of cancers. Here, we provide an overview of conventional SLN biopsy and ICG-guided SLN mapping techniques for oral cancer. Although ICG has many strengths, it still has limitations regarding its potential use as an ideal compound for SLN mapping. The development of novel fluorophores and imaging technology is needed for accurate identification of SLNs, which will allow precision surgery that would reduce morbidities and increase patient survival.

Near-infrared intraoperative imaging of pelvic autonomic nerves: a pilot study

BACKGROUND

The pelvic autonomic nerves control and regulate anorectal and urogenital function. The dysfunction of pelvic autonomic nerves lead to disorders of anorectum, bladder and male sex organs. Thus the intraoperative identification of pelvic autonomic nerves could be crucial in complications prevention and diseases treatment. Our clinical trial aims at estimating the effectiveness and validity of intraoperative indocyanine green fluorescence imaging in pelvic autonomic nerves identification.

METHODS

Intraoperative fluorescence imaging using indocyanine green was performed in ten patients and the feasibility was determined. From February 2019 to June 2019, the seven patients undergoing laparoscopic colorectal resection was administrated 4.5 mg/Kg indocyanine green 24 h before surgery. The near-infrared fluorescence imaging was conducted during surgery. A novel white light and near-infrared dual-channel laparoscopic equipment was applied. For each patient, signal-background ratio values for pelvic autonomic nerves were recorded and analyzed.

RESULTS

We confirmed the dose and timing of indocyanine green administration was 4.5 mg/Kg and 24 h before surgery. Using the dual laparoscopic equipment, we could observe the splanchnic plexus, inferior mesenteric artery plexus, and sacral plexus successfully with a high signal background ratio value of 3.18 (standard deviation: 0.48).

CONCLUSION

This pilot trial shows feasibility of intraoperative indocyanine green fluorescence imaging in pelvic autonomic nerves observation. It demonstrates that nerves can be visualized using alternative imaging techniques but it is not ready yet for prime time. This technique might aid observation with white light alone. Registration number: ChiCTR1900025336.

Current Intraoperative Imaging Techniques to Improve Surgical Resection of Laryngeal Cancer: A Systematic Review

Simple Summary

Laryngeal cancer is a prevalent head and neck malignancy, with poor prognosis and low survival rates for patients with advanced disease. The recurrence rate for advanced laryngeal cancer is between 25 and 50%. In order to improve surgical resection of laryngeal cancer and reduce local recurrence rates, various intraoperative optical imaging techniques have been investigated. In this systematic review we identify these technologies, evaluating the current state and future directions of optical imaging for this indication. Evidently, the investigated imaging modalities are generally unsuitable for deep margin assessment, and, therefore, inadequate to guide resection in advanced laryngeal disease. We discuss two optical imaging techniques that can overcome these limitations and suggest how they can be used to achieve adequate margins in laryngeal cancer at all stages.

Abstract

Laryngeal cancer is a prevalent head and neck malignancy, with poor prognosis and low survival rates for patients with advanced disease. Treatment consists of unimodal therapy through surgery or radiotherapy in early staged tumors, while advanced stage tumors are generally treated with multimodal chemoradiotherapy or (total) laryngectomy followed by radiotherapy. Still, the recurrence rate for advanced laryngeal cancer is between 25 and 50%. In order to improve surgical resection of laryngeal cancer and reduce local recurrence rates, various intraoperative optical imaging techniques have been investigated. In this systematic review, we identify these technologies, evaluating the current state and future directions of optical imaging for this indication. Narrow-band imaging (NBI) and autofluorescence (AF) are established tools for early detection of laryngeal cancer. Nonetheless, their intraoperative utility is limited by an intrinsic inability to image beyond the (sub-)mucosa. Likewise, contact endoscopy (CE) and optical coherence tomography (OCT) are technically cumbersome and only useful for mucosal margin assessment. Research on fluorescence imaging (FLI) for this application is sparse, dealing solely with nonspecific fluorescent agents. Evidently, the imaging modalities that have been investigated thus far are generally unsuitable for deep margin assessment. We discuss two optical imaging techniques that can overcome these limitations and suggest how they can be used to achieve adequate margins in laryngeal cancer at all stages.

Real-time fluorescence imaging in intraoperative decision making for cancer surgery

Fluorescence-guided surgery is an intraoperative optical imaging method that provides surgeons with real-time guidance for the delineation of tumours. Currently, in phase 1 and 2 clinical trials, evaluation of fluorescence-guided surgery is primarily focused on its diagnostic performance, although the corresponding outcome variables do not inform about the added clinical benefit of fluorescence-guided surgery and are challenging to assess objectively. Nonetheless, the effect of fluorescence-guided surgery on intraoperative decision making is the most objective outcome measurement to assess the clinical value of this imaging method. In this Review, we explore the study designs of existing trials of fluorescence-guided surgery that allow us to extract information on potential changes in intraoperative decision making, such as additional or more conservative resections. On the basis of this analysis, we offer recommendations on how to report changes in intraoperative decision making that result from fluorescence imaging, which is of utmost importance for the widespread clinical implementation of fluorescence-guided surgery.

Clinical translation and implementation of optical imaging agents for precision image-guided cancer surgery

INTRODUCTION

The field of tumor-specific fluorescence-guided surgery has seen a significant increase in the development of novel tumor-targeted imaging agents. Studying patient benefit using intraoperative fluorescence-guided imaging for cancer surgery is the final step needed for implementation in standard treatment protocols. Translation into phase III clinical trials can be challenging and time consuming. Recent studies have helped to identify certain waypoints in this transition phase between studying imaging agent efficacy (phase I-II) and proving patient benefit (phase III).

TRIAL INITIATION

Performing these trials outside centers of expertise, thus involving motivated clinicians, training them, and providing feedback on data quality, increases the translatability of imaging agents and the surgical technique. Furthermore, timely formation of a trial team which oversees the translational process is vital. They are responsible for establishing an imaging framework (camera system, imaging protocol, surgical workflow) and clinical framework (disease stage, procedure type, clinical research question) in which the trial is executed. Providing participating clinicians with well-defined protocols with the aim to answer clinically relevant research questions within the context of care is the pinnacle in gathering reliable trial data.

OUTLOOK

If all these aspects are taken into consideration, tumor-specific fluorescence-guided surgery is expected be of significant value when integrated into the diagnostic work-up, surgical procedure, and follow-up of cancer patients. It is only by involving and collaborating with all stakeholders involved in this process that successful clinical translation can occur.

AIM

Here, we discuss the challenges faced during this important translational phase and present potential solutions to enable final clinical translation and implementation of imaging agents for image-guided cancer surgery.

Optimal Dosing Strategy for Fluorescence-Guided Surgery with Panitumumab-IRDye800CW in Head and Neck Cancer

PURPOSE

To identify the optimal dosing strategy for fluorescence-guided surgery in patients with head and neck squamous cell carcinoma, we conducted a dose-ranging study evaluating the anti-epidermal growth factor receptor (EGFR) therapeutic antibody, panitumumab, that was fluorescently labeled with the near-infrared dye IRDye800CW.

PROCEDURES

Patients (n = 24) received either 0.5 or 1.0 mg/kg panitumumab-IRDye800CW in the weight-based dosing group or 25 or 50 mg panitumumab-IRDye800CW in the fixed dosing group. Following surgery, whole primary specimens were imaged in a closed-field device and the mean fluorescence intensity (MFI) and tumor-to-background ratio (TBR) were assessed. Clinical variables, including dose, time of infusion-to-surgery, age, unlabeled dose, gender, primary tumor site, and tumor size, were analyzed to evaluate the factors affecting the fluorescence intensity in order to identify the optimal dose for intraoperative fluorescence imaging.

RESULTS

A total of 24 primary tumor specimens were imaged and analyzed in this study. Although no correlations between TBR and dose of panitumumab-IRDye800CW were found, there were moderate-strong correlations between the primary tumor MFI and panitumumab-IRDye800CW dose for fixed dose (mg) (R² = 0.42) and for dose/weight (mg/kg) (R² = 0.54). Results indicated that the optimal MFI was at approximately 50 mg for fixed dose and 0.75 mg/kg for dose/weight. No significant differences were found for the primary tumor MFI and TBRs between the weight-based dosing and the fixed dosing groups. MFIs significantly increased when the infusion-to-surgery window was reduced to within 2 days (vs. 3 days or more, p < 0.05).

CONCLUSIONS

Antibody-based imaging for surgical resection is under investigation in multiple clinical trials. Our data suggests that a fixed dose of 50 mg is an appropriate diagnostic dose for successful surgical fluorescence imaging.

Fluorescently Labeled Cetuximab-IRDye800 for Guided Surgical Excision of Ameloblastoma: A Proof of Principle Study

PURPOSE

Fluorescently labeled epidermal growth factor receptor (EGFR) antibodies have successfully identified microscopic tumors in multiple in vivo models of human cancers with limited toxicity. The present study sought to demonstrate the ability of fluorescently labeled anti-EGFR, cetuximab-IRDye800, to localize to ameloblastoma (AB) tumor cells in vitro and in vivo.

MATERIAL AND METHODS

EGFR expression in AB cells was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry. Primary AB cells were labeled in vitro with cetuximab-IRDye800 or nonspecific IgG-IRDye800. An in vivo patient-derived xenograft (PDX) model of AB was developed. The tumor tissue from 3 patients was implanted subcutaneously into immunocompromised mice. The mice received an intravenous injection of cetuximab-IRDye800 or IgG-IRDye800 and underwent imaging to detect infrared fluorescence using a Pearl imaging system (LI-COR Biosciences, Lincoln, NE). After resection of the overlying skin, the tumor/background ratios (TBRs) were calculated and statistically analyzed using a paired t test.

RESULTS

EGFR expression was seen in all AB samples. Tumor-specific labeling was achieved, as evidenced by a positive fluorescence signal from cetuximab-IRDye800 binding to AB cells, with little staining seen in the negative controls treated with IgG-IRDye800. In the animal PDX model, imaging revealed that the TBRs produced by cetuximab were significantly greater than those produced by IgG on days 7 to 14 for AB-20 tumors. After skin flap removal to simulate a preresection state, the TBRs increased with cetuximab and were significantly greater than the TBRs with the IgG control for PDX tumors derived from the 3 patients with AB. The excised tissues were embedded in paraffin and examined to confirm the presence of tumor.

CONCLUSIONS

Fluorescently labeled anti-EGFR demonstrated specificity for AB cells and PDX tumors. The present study is the first report of tumor-specific, antibody-based imaging of odontogenic tumors, of which AB is one of the most clinically aggressive. We expect this technology will ultimately assist surgeons treating AB by helping to accurately assess the tumor margins during surgery, leading to improved long-term local tumor control and less surgical morbidity.

Intraoperative Tumor Assessment Using Real-Time Molecular Imaging in Head and Neck Cancer Patients

BACKGROUND

In head and neck cancer, surgical resection using primarily visual and tactile feedback is considered the gold standard for solid tumors. Due to high numbers of tumor-involved surgical margins, which are directly correlated to poor clinical outcomes, intraoperative optical imaging trials have rapidly proliferated over the past 5 years. However, few studies report on intraoperative in situ imaging data that could support surgical resection. To demonstrate the clinical application of in situ surgical imaging, we report on the imaging data that are directly (ie in real-time) available to the surgeon.

STUDY DESIGN

Fluorescence intensities and tumor-to-background ratios (TBRs) were determined from the intraoperative imaging data-the view as seen by the surgeon during tumor resection-of 20 patients, and correlated to patient and tumor characteristics including age, sex, tumor site, tumor size, histologic differentiation, and epidermal growth factor receptor (EGFR) expression. Furthermore, different lighting conditions in regard to surgical workflow were evaluated.

RESULTS

Under these circumstances, intraoperative TBRs of the primary tumors averaged 2.2 ± 0.4 (range 1.5 to 2.9). Age, sex, tumor site, and tumor size did not have a significant effect on open-field intraoperative molecular imaging of the primary tumors (p > 0.05). In addition, variation in EGFR expression levels or the presence of ambient light did not seem to alter TBRs.

CONCLUSIONS

We present the results of successful in situ intraoperative imaging of primary tumors alongside the optimal conditions with respect to both molecular image acquisition and surgical workflow. This study illuminates the potentials of open-field molecular imaging to assist the surgeon in achieving successful cancer removal.

Multimodal image-guided surgery of HER2-positive breast cancer using [111In]In-DTPA-trastuzumab-IRDye800CW in an orthotopic breast tumor model

Background

Combining modalities using dual-labeled antibodies may allow preoperative and intraoperative tumor localization and could be used in image-guided surgery to improve complete tumor resection. Trastuzumab is a monoclonal antibody against the human epidermal growth factor-2 (HER2) receptor and dual-labeled trastuzumab with both a fluorophore (IRDye800CW) and a radioactive label (¹¹¹In) can be used for multimodal imaging of HER2-positive breast cancer. The aim of this study was to demonstrate the feasibility of HER2-targeted multimodal imaging using [¹¹¹In]In-DTPA-trastuzumab-IRDye800CW in an orthotopic breast cancer model.

Methods

Trastuzumab was conjugated with p-isothiocyanatobenzyl (ITC)-diethylenetriaminepentaacetic acid (DTPA) and IRDye800CW-NHS ester and subsequently labeled with ¹¹¹In. In a dose escalation study, the biodistribution of 10, 30, and 100 μg [¹¹¹In]In-DTPA-trastuzumab-IRDye800CW was determined 48 h after injection in BALB/c nude mice with orthotopic high HER2-expressing tumors. Also, a biodistribution study was performed in a low HER2-expressing breast cancer model. In addition, multimodal image-guided surgery was performed in each group. Autoradiography, fluorescence microscopy, and immunohistochemically stained slices of the tumors were compared for co-localization of tumor tissue, HER2 expression, fluorescence, and radiosignal.

Results

Based on the biodistribution data, a 30 μg dose of dual-labeled trastuzumab (tumor-to-blood ratio 13 ± 2) was chosen for all subsequent studies. [¹¹¹In]In-DTPA-trastuzumab-IRDye800CW specifically accumulated in orthotopic HER2-positive BT474 tumors (101 ± 7 %IA/g), whereas uptake in orthotopic low HER2-expressing MCF7 tumor was significantly lower (1.2 ± 0.2 %IA/g, p = 0.007). BT474 tumors could clearly be visualized with both micro-SPECT/CT, fluorescence imaging and subsequently, image-guided resection was performed. Immunohistochemical analyses of BT474 tumors demonstrated correspondence in fluorescence, radiosignal, and high HER2 expression.

Conclusions

Dual-labeled trastuzumab showed specific accumulation in orthotopic HER2-positive BT474 breast tumors with micro-SPECT/CT and fluorescence imaging and enabled image-guided tumor resection. In the clinical setting, [¹¹¹In]In-DTPA-trastuzumab-IRDye800CW could be valuable for preoperative detection of (metastatic) tumors by SPECT/CT imaging, and intraoperative localization by using a gamma probe and fluorescence image-guided surgery to improve radical resection of tumor tissue in patients with HER2-positive tumors.

Fluorescence Guidance in Surgical Oncology: Challenges, Opportunities, and Translation

Surgical resection continues to function as the primary treatment option for most solid tumors. However, the detection of cancerous tissue remains predominantly subjective and reliant on the expertise of the surgeon. Surgery that is guided by fluorescence imaging has shown clinical relevance as a new approach to detecting the primary tumor, tumor margins, and metastatic lymph nodes. It is a technique to reduce recurrence and increase the possibility of a curative resection. While significant progress has been made in developing this emerging technology as a tool to assist the surgeon, further improvements are still necessary. Refining imaging agents and tumor targeting strategies to be a precise and reliable surgical strategy is essential in order to translate this technology into patient care settings. This review seeks to provide a comprehensive update on the most recent progress of fluorescence-guided surgery and its translation into the clinic. By highlighting the current status and recent developments of fluorescence image-guided surgery in the field of surgical oncology, we aim to offer insight into the challenges and opportunities that require further investigation.

Gold nanoclusters as a contrast agent for image-guided surgery of head and neck tumors

With the objective to evaluate the potential of ultra-small gold (Au) nanoclusters (NCs) for optical image-guided surgery, we synthesized and characterized AuNCs shelled by zwitterionic or pegylated ligands. The toxicity of the different AuNCs was evaluated on the Head and Neck Squamous Cell Carcinoma (HNSCC) CAL-33 and SQ20B cell lines in vitro. The safer AuNCs were administrated intravenously to mice for the determination of the pharmacokinetic properties. Biodistributions were performed on orthotopic CAL-33 HNSCC-bearing mice. Finally, the AuNCs were used for image-guided surgery, allowing the increase of the survival time vs. control animals, and the number of animals without any local recurrence.

Surgical margins in oral cavity squamous cell carcinoma: Current practices and future directions

OBJECTIVE

To discuss the current available techniques for intraoperative margin assessment in the surgical treatment of oral squamous cell carcinoma (OSCC) through a review of the available literature.

METHODS

A systematic review was undertaken of the available English literature between 2008 through 2018 regarding surgical margins in OCSS. A total of 893 relevant articles were returned; 144 met criteria for review; and 64 articles were included.

RESULTS

In this review, we discuss the data surrounding the use of frozen section in OCSS. Additionally, alternative techniques for margin assessment are discussed, including Mohs, molecular analysis, nonfluorescent dyes, fluorescent dyes, autofluorescent imaging, narrow-band imaging, optical coherence tomography, confocal microscopy, high-resolution microendoscopy, and spectroscopy. For each technique, particular emphasis is placed on the local recurrence, disease-free survival, and overall survival rates when available.

CONCLUSION

This review provides support for the practice of specimen-driven margin assessment when using frozen section analysis to improve the utility of the results. Finally, several alternatives for intraoperative margin assessment currently under investigation, including pathologic, wide-field imaging and narrow-field imaging techniques, are presented. We aim to fuel further investigation into methods for margin assessment that will improve survival for patients with OSCC through a critical analysis of the available techniques.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:128-138, 2020.

The Clinical Application of Fluorescence-Guided Surgery in Head and Neck Cancer

Although surgical resection has been the primary treatment modality of solid tumors for decades, surgeons still rely on visual cues and palpation to delineate healthy from cancerous tissue. This may contribute to the high rate (up to 30%) of positive margins in head and neck cancer resections. Margin status in these patients is the most important prognostic factor for overall survival. In addition, second primary lesions may be present at the time of surgery. Although often unnoticed by the medical team, these lesions can have significant survival ramifications. We hypothesize that real-time fluorescence imaging can enhance intraoperative decision making by aiding the surgeon in detecting close or positive margins and visualizing unanticipated regions of primary disease. The purpose of this study was to assess the clinical utility of real-time fluorescence imaging for intraoperative decision making. Methods: Head and neck cancer patients (n = 14) scheduled for curative resection were enrolled in a clinical trial evaluating panitumumab-IRDye800CW for surgical guidance (NCT02415881). Open-field fluorescence imaging was performed throughout the surgical procedure. The fluorescence signal was quantified as signal-to-background ratios to characterize the fluorescence contrast of regions of interest relative to background. Results: Fluorescence imaging was able to improve surgical decision making in 3 cases (21.4%): identification of a close margin (n = 1) and unanticipated regions of primary disease (n = 2). Conclusion: This study demonstrates the clinical applications of fluorescence imaging on intraoperative decision making. This information is required for designing phase III clinical trials using this technique. Furthermore, this study is the first to demonstrate this application for intraoperative decision making during resection of primary tumors.

Fluorescent humanized anti-CEA antibody specifically labels metastatic pancreatic cancer in a patient-derived orthotopic xenograft (PDOX) mouse model

Pancreatic cancer is a highly lethal disease in part due to incomplete tumor resection. Targeting by tumor-specific antibodies conjugated with a fluorescent label can result in selective labeling of cancer in vivo for surgical navigation. In the present study, we describe a patient-derived orthotopic xenograft model of pancreatic cancer that recapitulated the disease on a gross and microscopic level, along with physiologic clinical manifestations. We additionally show that the use of an anti-CEA antibody conjugated to the near-infrared (NIR) fluorescent dye, IRDye800CW, can selectively highlight the pancreatic cancer and its metastases in this model with a tumor-to-background ratio of 3.5 (SEM 0.9). The present results demonstrate the clinical potential of this labeling technique for fluorescence-guided surgery of pancreatic cancer.

Determination of Tumor Margins with Surgical Specimen Mapping Using Near-Infrared Fluorescence

For many solid tumors, surgical resection remains the gold standard and tumor-involved margins are associated with poor clinical outcomes. Near-infrared (NIR) fluorescence imaging using molecular agents has shown promise for in situ imaging during resection. However, for cancers with difficult imaging conditions, surgical value may lie in tumor mapping of surgical specimens. We thus evaluated a novel approach for real-time, intraoperative tumor margin assessment. Twenty-one adult patients with biopsy-confirmed squamous cell carcinoma arising from the head and neck (HNSCC) scheduled for standard-of-care surgery were enrolled. Cohort 1 (n = 3) received panitumumab-IRDye800CW at an intravenous microdose of 0.06 mg/kg, cohort 2A (n = 5) received 0.5 mg/kg, cohort 2B (n = 7) received 1 mg/kg, and cohort 3 (n = 6) received 50 mg. Patients were followed 30 days postinfusion and adverse events were recorded. Imaging was performed using several closed- and wide-field devices. Fluorescence was histologically correlated to determine sensitivity and specificity. In situ imaging demonstrated tumor-to-background ratio (TBR) of 2 to 3, compared with ex vivo specimen imaging TBR of 5 to 6. We obtained clear differentiation between tumor and normal tissue, with a 3-fold signal difference between positive and negative specimens (P < 0.05). We achieved high correlation of fluorescence intensity with tumor location with sensitivities and specificities >89%; fluorescence predicted distance of tumor tissue to the cut surface of the specimen. This novel method of detecting tumor-involved margins in surgical specimens using a cancer-specific agent provides highly sensitive and specific, real-time, intraoperative surgical navigation in resections with complex anatomy, which are otherwise less amenable to image guidance.Significance: This study demonstrates that fluorescence can be used as a sensitive and specific method of guiding surgeries for head and neck cancers and potentially other cancers with challenging imaging conditions, increasing the probability of complete resections and improving oncologic outcomes. Cancer Res; 78(17); 5144-54. ©2018 AACR.

The development of fluorescence guided surgery for pancreatic cancer: from bench to clinic

INTRODUCTION

Surgeons face major challenges in achieving curative R0 resection for pancreatic cancers. When the lesion is localized, they must appropriately visualize the tumor, determine appropriate resection margins, and ensure complete tumor clearance. Real-time surgical navigation using fluorescence-guidance has enhanced the ability of surgeons to see the tumor and has the potential to assist in achieving more oncologically complete resections. When there is metastatic disease, fluorescence enhancement can help detect these lesions and prevent unnecessary and futile surgeries. Areas covered: This article reviews different approaches for delivery of a fluorescence signal, their pre-clinical and clinical developments for fluorescence guided surgery, the advantages/challenges of each, and their potential for advancements in the future. Expert commentary: A variety of molecular imaging techniques are available for delivering tumor-specific fluorescence signals. Significant advancements have been made in the past 10 years due to the large body of literature on targeted therapies and this has translated into rapid developments of tumor-specific probes.

Anatomical locations in the oral cavity where surgical resections of oral squamous cell carcinomas are associated with a close or positive margin-a retrospective study

OBJECTIVES

This study aimed to identify anatomical areas where resections of oral squamous cell carcinomas (OSCC) are significantly associated with close or positive margins.

MATERIALS AND METHODS

This retrospective study included 330 patients with a primary OSCC from 2010 to 2015. Patient and tumour data were categorised into three groups by R-status (R0 [clear], ≥ 5 mm, 185 patients [56.06%]; R1 [positive], < 1 mm, 24 patients [7.27%]; and R0 [close], 1-5 mm, 121 patients [36.67%]).

RESULTS

Areas where resections were significantly associated with close or positive margins were the hard palate (p < 0.001), buccal mucosa (p = 0.03), floor of the mouth (p = 0.004), lower alveolar ridge (p = 0.01), retromolar triangle (p = 0.005), and dorsal tongue (p = 0.02).

CONCLUSIONS

Anatomical areas were identified in the oral cavity where it is challenging to resect OSCCs with an adequate safety margin.

CLINICAL RELEVANCE

These results may enable surgeons to achieve a postulated safe distance during tumour resection, leading to a survival benefit for patients.

Tumor-Specific Labeling of Pancreatic Cancer Using a Humanized Anti-CEA Antibody Conjugated to a Near-Infrared Fluorophore

BACKGROUND/PURPOSE

Development of a humanized fluorophore-conjugated antibody that can improve contrast for fluorescence-guided oncologic surgeries.

METHODS

BxPC-3-GFP pancreatic cancer cells were injected into flanks of nude mice. Fragments of subcutaneous tumors were grafted onto the pancreatic tail of recipient mice to create orthotopic xenograft models of pancreatic cancer. After tumors developed for 4 weeks, a humanized anti-carcinoembryonic antigen antibody conjugated to an 800 nm near-infrared fluorescent dye (hM5A-IR800) was injected intravenously. Mice were imaged at 6, 12, 24, 48, and 72 h after injection.

RESULTS

Fluorescence imaging showed that hM5A-IR800 specifically localized to BxPC-3 human pancreatic cancer cells. The fluorescent probe localized to cell surfaces in vitro and specifically co-localized with green fluorescent protein-labeled tumors in an orthotopic pancreatic xenograft model in vivo. Serial imaging at specific time points showed peak signal intensity of the orthotopic pancreatic tumor at 48 h; this time point corresponded with a maximal tumor-to-background ratio (TBR) of 16.6 at 48 h.

DISCUSSION

hM5A-IR800 was successfully able to specifically label orthotopic pancreatic tumors in situ. The longer wavelength allowed deeper tissue penetration, particularly in tumor areas covered by normal pancreatic parenchyma. The probe had expected kinetics for an antibody-fluorophore conjugate, with the peak signal intensity reached at 48 h. A clear tumor signal was observed with a TBR > 5 at all time points, with high contrast (TBR of 16.6) at 48 h.

CONCLUSION

hM5A-IR800 demonstrated excellent tumor localization and a very bright signal. It is a promising agent for future clinical fluorescence-guided surgery applications.

Near-infrared Intraoperative Imaging of Thoracic Sympathetic Nerves: From Preclinical Study to Clinical Trial

The sympathetic nervous system controls and regulates the activities of the heart and other organs. Sympathetic nervous system dysfunction leads to disease. Therefore, intraoperative real-time imaging of thoracic sympathetic nerves (ITSN) would be of great clinical significance for diagnosis and therapy. The aim of this experimental study was to evaluate the feasibility and validity of intraoperative ITSN using indocyanine green (ICG).

METHODS

ITSN using ICG was performed on 10 rabbits to determine its feasibility. Animals were allocated to two groups. The rabbits in one group received the same dose of ICG, but were observed at different times. The rabbits in the other group were administered different doses of ICG, but were observed at the same time. Signal to background ratio (SBR) was measured in regions of interest in all rabbits. Furthermore, fifteen consecutive patients with pulmonary nodules were intravenously injected with ICG 24 h preoperatively and underwent near-infrared (NIR) fluorescence imaging (FI) thoracoscopic surgeries between July 2015 and June 2016. A novel self-developed NIR and white-light dual-channel thoracoscope system was used. SBRs of thoracic sympathetic nerves were calculated in all patients.

RESULTS

In the preclinical study, we were able to precisely recognize each rabbit's second (T2) to fifth (T5) thoracic ganglia on both sides of the spine using ITSN with ICG. In addition, we explored the relationship between SBR and the injection time of ICG and that between SBR and the dose of ICG. Using the novel dual-channel thoracoscope system, we were able to locate the ganglia from the stellate ganglion (SG) to the sixth thoracic ganglion (T6), as well as the chains between these ganglia in all patients with a high SBR value of 3.26 (standard deviation: 0.57). The pathological results confirmed our findings.

CONCLUSION

We were able to use ICG FI to distinguish thoracic sympathetic nerves during NIR thoracoscopic surgery. The technique may replace the rib-oriented method as standard practice for mapping the thoracic sympathetic nerves.

Characterizing the detection threshold for optical imaging in surgical oncology

BACKGROUND AND OBJECTIVES

Optical imaging to guide cancer resections is rapidly transitioning into the operating room. However, the sensitivity of this technique to detect subclinical disease is yet characterized. The purpose of this study was to determine the minimum range of cancer cells that can be detected by antibody-based fluorescence imaging.

METHODS

2LMP (breast), COLO-205 (colon), MiaPaca-2 (pancreas), and SCC-1 (head and neck) cells incubated in vitro with cetuximab-IRDye800CW (dose range 8.6-86 nM) were implanted subcutaneously in mice (n = 3 mice, 5 tumors/mouse). Following incubation with 8.6 × 10^-2  µM of cetuximab-IRDye800CW in vitro, serial dilutions of each cell type (1 × 10³ -1 × 10⁶ ) were implanted subcutaneously (n = 3, 5 tumors/mouse). Tumors were imaged with Pearl Impulse and Xenogen IVIS 100 imaging systems. Scatchard analysis was performed to determine receptor density and kinetics for each cell line.

RESULTS

Under conditions of minimal cetuximab-IRDye800CW exposure to low cellular quantity, closed-field fluorescence imaging theoretically detected a minimum of 4.2 × 10⁴ -9.5 × 10⁴ 2LMP cells, 1.9 × 10⁵ -4.5 × 10⁵ MiaPaca-2 cells, and 2.4 × 10⁴ -6.7 × 10⁴ SCC-1 cells; COLO-205 cells could not be identified. Higher EGFR-mediated uptake of cetuximab correlated with sensitivity of detection.

CONCLUSION

This study supports the clinical utility of cetuximab-IRDye800CW to sensitively localize subclinical disease in the surgical setting.