Near-Infrared Intraoperative Molecular Imaging Can Locate Metastases to the Lung

A Phase 2 Multicenter Clinical Trial of Intraoperative Molecular Imaging of Lung Cancer with a pH-Activatable Nanoprobe

PURPOSE

Intraoperative molecular imaging (IMI) uses tumor-targeted optical contrast agents to improve identification and clearance of cancer. Recently, a probe has been developed that only fluoresces when activated in an acidic pH, which is common to many malignancies. We report the first multicenter Phase 2 trial of a pH-activatable nanoprobe (pegsitacianine, ONM-100) for IMI of lung cancer.

METHODS

Patients with suspected or biopsy-confirmed lung cancer scheduled for sublobar resection were administered a single intravenous infusion of pegsitacianine (1 mg/kg) one to three days prior to surgery. Intraoperatively, the patients underwent a white light thoracoscopic evaluation, and then were imaged with an NIR thoracoscope to detect tumor fluorescence. The primary study endpoint was the proportion of patients with a clinically significant event (CSE) which was defined as an intraoperative discovery during IMI that led to a change in the surgical procedure. Possible CSEs included (i) localizing the index lung nodule that could not be located by white light, (ii) identifying a synchronous malignant lesion, or (iii) recognizing a close surgical margin (< = 10 mm). Secondary endpoints were sensitivity, specificity, NPV, and PPV of pegsitacianine in detecting tumor-containing tissue. The safety evaluation was based on adverse event reporting, clinical laboratory parameters, and physical examinations.

RESULTS

Twenty patients were confirmed as eligible and administered pegsitacianine. Most of the patients were female (n = 12 [60%]), middle-aged (mean age 63.4 years), and former smokers (n = 13 [65%], 28.6 mean pack years). Mean lesion size was 1.9 cm, and most lesions (n = 17 [85%]) were malignant. The most common histologic subtype was adenocarcinoma (n = 9). By utilizing IMI with pegsitacianine, one patient had a CSE in the detection of a close margin and another had localization of a tumor not detectable by traditional surgical means. Six of 19 (31.6%) malignant lesions fluoresced with mean tumor-to-background ratio (TBR) of 3.00, as compared to TBR of 1.20 for benign lesions (n = 3). Sensitivity and specificity of pegsitacianine-based IMI for detecting malignant tissue was 31.6% and 33.3%, respectively. Positive predictive value (PPV) and negative predictive value (NPV) of pegsitacianine-based IMI was 75% and 7.1%, respectively. Pegsitacianine-based imaging was not effective in differentiating benign and malignant lymph nodes. From a safety perspective, no drug-related serious adverse events occurred. Four patients experienced mild pegsitacianine-related infusion reactions which required discontinuing the study drug with complete resolution of symptoms.

CONCLUSIONS

Pegsitacianine-based IMI, though well tolerated from a safety perspective, does not consistently label lung tumors during resection and does not provide significant clinical benefit over existing standards of surgical care. The biology of lung tumors may not be as acidic as other solid tumors in the body thereby not activating the probe as predicted.

Non-Small Cell Lung Cancer Imaging Using a Phospholipase A2 Activatable Fluorophore

Lung cancer, the most common cause of cancer-related death in the United States, requires advanced intraoperative detection methods to improve evaluation of surgical margins. In this study we employed DDAO-arachidonate (DDAO-A), a phospholipase A2 (PLA2) activatable fluorophore, designed for the specific optical identification of lung cancers in real-time during surgery. The in vitro fluorescence activation of DDAO-A by porcine sPLA2 was tested in various liposomal formulations, with 100 nm extruded EggPC showing the best overall characteristics. Extruded EggPC liposomes containing DDAO-A were tested for their stability under various storage conditions, demonstrating excellent stability for up to 4 weeks when stored at -20 °C or below. Cell studies using KLN 205 and LLC1 lung cancer cell lines showed DDAO-A activation was proportional to cell number. DDAO-A showed preferential activation by human recombinant cPLA2, an isoform highly specific to arachidonic acid-containing lipids, when compared to a control probe, DDAO palmitate (DDAO-P). In vivo studies with DBA/2 mice bearing KLN 205 lung tumors recapitulated these results, with preferential activation of DDAO-A relative to DDAO-P following intratumoral injection. Topical application of DDAO-A-containing liposomes to human (n = 10) and canine (n = 3) lung cancers ex vivo demonstrated the preferential activation of DDAO-A in tumor tissue relative to adjacent normal lung tissue, with fluorescent tumor-to-normal ratios (TNR) of up to 5.2:1. The combined results highlight DDAO-A as a promising candidate for clinical applications, showcasing its potential utility in intraoperative and back-table imaging and topical administration during lung cancer surgeries. By addressing the challenge of residual microscopic disease at resection margins and offering stability in liposomal formulations, DDAO-A emerges as a potentially valuable tool for advancing precision lung cancer surgery and improving curative resection rates.

Precision Oncology in Lung Cancer Surgery

Precision in lung cancer surgery is our ability to use the most cutting edge and up to date information to provide personalized and targeted surgical care to our patients. It aims to tailor patient care to patient and tumor characteristics and susceptibilities as well as to optimize the ways treatments are administered. This may include specific perioperative medical treatment, changing operative techniques to more minimally invasive ones if the situation permits, performing sub-anatomical surgeries when possible, and using innovative tumor visualization methods to enhance detection of previously occult disease to ultimately decrease the extent of the planned resection.

Children's Oncology Group's 2023 blueprint for research: Surgery

Surgery plays a crucial role in the treatment of children with solid malignancies. A well-conducted operation is often essential for cure. Collaboration with the primary care team is important for determining if and when surgery should be performed, and if performed, an operation must be done in accordance with well-established standards. The long-term consequences of surgery also need to be considered. Indications and objectives for a procedure vary. Providing education and developing and analyzing new research protocols that include aims relevant to surgery are key objectives of the Surgery Discipline of the Children's Oncology Group. The critical evaluation of emerging technologies to ensure safe, effective procedures is another key objective. Through research, education, and advancing technologies, the role of the pediatric surgeon in the multidisciplinary care of children with solid malignancies will continue to evolve.

A pH-Activatable Nanoprobe Labels Diverse Histologic Subtypes of Human Lung Cancer During Resection

BACKGROUND

Intraoperative molecular imaging (IMI) uses tumor-targeted optical contrast agents to improve identification and clearance of cancer during surgery. Recently, pH-activatable contrast agents have been developed but none has been tested in lung cancer. Here, we report the successful clinical translation of pegsitacianine (ONM-100), a pH-activatable nanoprobe, for fluorescence-guided lung cancer resection.

METHODS

We first characterized the pH setpoint for pegsitacianine fluorescence activation in vitro. We then optimized the specificity, dosing, and timing of pegsitacianine in murine flank xenograft models of lung adenocarcinoma and squamous cell carcinoma. Finally, we tested pegsitacianine in humans undergoing lung cancer surgery as part of an ongoing phase 2 trial.

RESULTS

We found that the fluorescence activation of pegsitacianine occurred below physiologic pH in vitro. Using preclinical models of lung cancer, we found that the probe selectively labeled both adenocarcinoma and squamous cell carcinoma xenografts (mean tumor-to-background ratio [TBR] > 2.0 for all cell lines). In the human pilot study, we report cases in which pegsitacianine localized pulmonary adenocarcinoma and pulmonary squamous cell carcinoma (TBRs= 2.7 and 2.4) in real time to illustrate its successful clinical translation and potential to improve surgical management.

CONCLUSIONS

This translational study demonstrates the feasibility of pegsitacianine as an IMI probe to label the two most common histologic subtypes of human lung cancer.

Feasibility of indocyanine green-guided localization of pulmonary nodules in children with solid tumors

BACKGROUND

Clearing all pulmonary metastases is essential for curing pediatric solid tumors. However, intraoperative localization of such pulmonary nodules can be challenging. Therefore, an intraoperative tool that localizes pulmonary metastases is needed to improve diagnostic and therapeutic resections. Indocyanine green (ICG) real-time fluorescence imaging is used for this purpose in adult solid tumors, but its utility in pediatric solid tumors has not been determined.

METHODS

A single-center, open-label, nonrandomized, prospective clinical trial (NCT04084067) was conducted to assess the ability of ICG to localize pulmonary metastases of pediatric solid tumors. Patients with pulmonary lesions who required resection, either for therapeutic or diagnostic intent, were included. Patients received a 15-minute intravenous infusion of ICG (1.5 mg/kg), and pulmonary metastasectomy was performed the following day. A near-infrared spectroscopy iridium system was optimized to detect ICG, and all procedures were photo-documented and recorded.

RESULTS

ICG-guided pulmonary metastasectomies were performed in 12 patients (median age: 10.5 years). A total of 79 nodules were visualized, 13 of which were not detected by preoperative imaging. Histologic examination confirmed the following histologies: hepatoblastoma (n = 3), osteosarcoma (n = 2), and one each of rhabdomyosarcoma, Ewing sarcoma, inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, and papillary thyroid carcinoma. ICG guidance failed to localize pulmonary metastases in five (42%) patients who had inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, or papillary thyroid carcinoma.

CONCLUSIONS

ICG-guided identification of pulmonary nodules is not feasible for all pediatric solid tumors. However, it may localize most metastatic hepatic tumors and high-grade sarcomas in children.

Single-institution experience of 500 pulmonary resections guided by intraoperative molecular imaging

OBJECTIVE

Intraoperative molecular imaging (IMI) using tumor-targeted optical contrast agents can improve thoracic cancer resections. There are no large-scale studies to guide surgeons in patient selection or imaging agent choice. Here, we report our institutional experience with IMI for lung and pleural tumor resection in 500 patients over a decade.

METHODS

Between December 2011 and November 2021, patients with lung or pleural nodules undergoing resection were preoperatively infused with 1 of 4 optical contrast tracers: EC17, TumorGlow, pafolacianine, or SGM-101. Then, during resection, IMI was used to identify pulmonary nodules, confirm margins, and identify synchronous lesions. We retrospectively reviewed patient demographic data, lesion diagnoses, and IMI tumor-to-background ratios (TBRs).

RESULTS

Five hundred patients underwent resection of 677 lesions. We found that there were 4 types of clinical utility of IMI: detection of positive margins (n = 32, 6.4% of patients), identification of residual disease after resection (n = 37, 7.4%), detection of synchronous cancers not predicted on preoperative imaging (n = 26, 5.2%), and minimally invasive localization of nonpalpable lesions (n = 101 lesions, 14.9%). Pafolacianine was most effective for adenocarcinoma-spectrum malignancies (mean TBR, 2.84), and TumorGlow was most effective for metastatic disease and mesothelioma (TBR, 3.1). False-negative fluorescence was primarily seen in mucinous adenocarcinomas (mean TBR, 1.8), heavy smokers (>30 pack years; TBR, 1.9), and tumors greater than 2.0 cm from the pleural surface (TBR, 1.3).

CONCLUSIONS

IMI may be effective in improving resection of lung and pleural tumors. The choice of IMI tracer should vary by the surgical indication and the primary clinical challenge.

Clinical application of indocyanine green fluorescence imaging navigation for pediatric renal cancer

Background

Indocyanine Green (ICG) fluorescence imaging has been widely used in the surgical treatment of adult renal cancers, but its application in pediatric renal cancers has rarely been reported. This study aims to summarize the experience of ICG fluorescence imaging in pediatric renal cancers and explores its safety and feasibility.

Methods

The clinical features, surgical information, ICG administration regimen, near infrared radiography data in vivo and ex vivo and pathological results of children with renal cancers using ICG navigation were analyzed and summarized.

Results

There were 7 cases of renal cancer, including 4 cases of Wilms tumor (WT), 1 case of malignant rhabdoid tumor of the kidney (MRTK) and 2 cases of renal cell carcinoma (RCC). By intraoperative intravenous injection of ICG from 2.5 to 5 mg (0.05-0.67 mg/kg), the tumors were visualized in 6 cases in vivo or ex vivo, and the tumor visualization failed in 1 case due to renal artery embolization before operation. By injecting 5 mg ICG into the normal renal tissue during the operation, 3 patients achieved fluorescent localization of sentinel lymph nodes. No ICG-related adverse reactions were found in any of the patients during or after operation.

Conclusions

ICG fluorescence imaging is safe and feasible for renal cancers in children. Intraoperative administration can achieve tumor and sentinel lymph node visualization which will facilitate the development of nephron sparing surgery (NSS). However, the technique is affected by ICG dose, anatomical conditions around the tumor, and renal blood flow. A proper dose of ICG and the complete removal of perirenal fat are helpful for the fluorescence imaging of the tumor. It has potential in the operation of renal cancer in children.

Comparative Experience of Short-wavelength Versus Long-wavelength Fluorophores for Intraoperative Molecular Imaging of Lung Cancer

BACKGROUND

Intraoperative molecular imaging (IMI) using tumor-targeted optical contrast agents can improve cancer resections. The optimal wavelength of the IMI tracer fluorophore has never been studied in humans and has major implications for the field. To address this question, we investigated 2 spectroscopically distinct fluorophores conjugated to the same targeting ligand.

METHODS

Between December 2011 and November 2021, patients with primary lung cancer were preoperatively infused with 1 of 2 folate receptor-targeted contrast tracers: a short-wavelength folate-fluorescein (EC17; λ em =520 nm) or a long-wavelength folate-S0456 (pafolacianine; λ em =793 nm). During resection, IMI was utilized to identify pulmonary nodules and confirm margins. Demographic data, lesion diagnoses, and fluorescence data were collected prospectively.

RESULTS

Two hundred eighty-two patients underwent resection of primary lung cancers with either folate-fluorescein (n=71, 25.2%) or pafolacianine (n=211, 74.8%). Most tumors (n=208, 73.8%) were invasive adenocarcinomas. We identified 2 clinical applications of IMI: localization of nonpalpable lesions (n=39 lesions, 13.8%) and detection of positive margins (n=11, 3.9%). In each application, the long-wavelength tracer was superior to the short-wavelength tracer regarding depth of penetration, signal-to-background ratio, and frequency of event. Pafolacianine was more effective for detecting subpleural lesions (mean signal-to-background ratio=2.71 vs 1.73 for folate-fluorescein, P <0.0001). Limit of signal detection was 1.8 cm from the pleural surface for pafolacianine and 0.3 cm for folate-fluorescein.

CONCLUSIONS

Long-wavelength near-infrared fluorophores are superior to short-wavelength IMI fluorophores in human tissues. Therefore, future efforts in all human cancers should likely focus on long-wavelength agents.

How effective is indocyanine green (ICG) in localization of malignant pulmonary nodules? A systematic review and meta-analysis

Background

Video-Assisted and Robotic-Assisted techniques become constantly more prominent practice in thoracic surgery for lung cancer. Furthermore, the increased frequency in detection of small lung cancers makes the intra-operative identification of these cancers even more challenging. Indocyanine Green (ICG) is one of the most commonly used dyes that assists surgeons identify small lung cancers intra-operatively. Our study aimed to evaluate the effectiveness and safety of ICG in lung cancer detection.

Methods

We performed a systematic review of the literature by screening the databases of MEDLINE, EMBASE, CENTRAL and Scopus until 30th April 2022 and the first 300 articles of Google Scholar for any suitable grey literature. We included any study that investigated the effectiveness of ICG in lung cancer detection. We excluded studies that explored the use of ICG only in identification of intersegmental planes, lymph node mapping, case reports and non-English articles. We aimed to perform a meta-analysis on test accuracy studies using hierarchical summary receiver operating characteristic (HSROC) and the bivariate random-effects models. In cases where the data for a localization technique was not sufficient for that analysis, it was presented with tables with narrative purposes. Each study was assessed for Risk of Bias (RoB) and Applicability using the QUADAS-2 tool.

Results

We found 30 eligible studies that included a total of 1,776 patients who underwent ICG localization of pulmonary nodules. We identified three ICG localization techniques: CT-guided, endobronchial and intravenous. From the 30 studies, 13 investigated CT-guided localization, 12 explored an endobronchial method while 8 studies administered ICG intravenously the median reported success rate was 94.3% (IQR: 91.4%–100%) and 98.3% (IQR: 94%–100%) for the first two techniques respectively. Intravenous ICG lung cancer localization showed Sensitivity of 88% (95% CI: 59%–0.97%) and Specificity of 25% (95% CI: 0.04%–0.74%). There were 15.2% (150/989) patients who experienced complications from CT guided ICG localization. No ICG-related complications were reported in endobronchial or intravenous techniques.

Conclusion

Our study provides a comprehensive review of the literature on ICG localization techniques for lung cancer. Current evidence suggests that ICG is boh effective and safe. Further prospective research with standardized protocols across multiple thoracic units is required in order to accurately validate these findings.

Assessment and Comparison of Three Dimensional Exoscopes for Near-Infrared Fluorescence-Guided Surgery using Second-Window Indocyanine-Green

Objective

Compared to microscopes, exoscopes have advantages in field-depth, ergonomics, and educational value. Exoscopes are especially well-poised for adaptation into fluorescence-guided surgery (FGS) due to their excitation source, light path, and image processing capabilities. We evaluated the feasibility of near-infrared FGS using a 3-dimensional (3D), 4 K exoscope with near-infrared fluorescence imaging capability. We then compared it to the most sensitive, commercially-available near-infrared exoscope system (3D and 960 p). In-vitro and intraoperative comparisons were performed.

Methods

Serial dilutions of indocyanine-green (1–2000 μg/mL) were imaged with the 3D, 4 K Olympus Orbeye (system 1) and the 3D, 960 p VisionSense Iridium (system 2). Near-infrared sensitivity was calculated using signal-to-background ratios (SBRs). In addition, three patients with brain tumors were administered indocyanine-green and imaged with system 1, with two also imaged with system 2 for comparison.

Results

Systems 1 and 2 detected near-infrared fluorescence from indocyanine green concentrations of >250 μg/L and >31.3 μg/L, respectively. Intraoperatively, system 1 visualized strong near-infrared fluorescence from two, strongly gadolinium-enhancing meningiomas (SBR=2.4, 1.7). The high-resolution, bright images were sufficient for the surgeon to appreciate the underlying anatomy in the near-infrared mode. However, system 1 was not able to visualize fluorescence from a weakly-enhancing intraparenchymal metastasis. In contrast, system 2 successfully visualized both the meningioma and the metastasis but lacked high resolution stereopsis.

Conclusion

Three-dimensional exoscope systems provide an alternative visualization platform for both standard microsurgery and near-infrared fluorescent guided surgery. However, when tumor fluorescence is weak (i.e., low fluorophore uptake, deep tumors), highly sensitive near-infrared visualization systems may be required.

Intraoperative near-infrared molecular imaging for diagnostic thoracoscopy in difficult clinical scenario

Precise diagnosis in intrathoracic malignancies is paramount for adequate treatment planning. Standard approach is histologic analysis from targeted biopsy obtained with different invasive procedures. Rarely, in difficult clinical scenarios, even gold standard diagnostic procedures can be ineffective in obtaining a satisfying result. Procedural developments and technological improvements applied to the chosen technique can be helpful to deal with such situation. We present two clinical cases of suspected intrathoracic malignancy in which repeated unsuccessful diagnostic procedures had already been attempted. We adopted a protocol based on intraoperative fluorescence during diagnostic thoracoscopy to increase diagnostic efficacy. In both cases we obtained a precise pathological diagnosis.

A study on setting standards for near-infrared fluorescence-image guided surgery (NIRFGS) time lapse monitoring based on preoperative liver function assessment

Background

This study aimed to explore the relationship between the fluorescence intensity of indocyanine green (ICG) in near-infrared fluorescence guided surgery (NIRFGS) and preoperative liver function indicators.

Methods

A total of 12 4T1 tumor-bearing mice were used for model establishment. Intraperitoneal injection (i.p.) of 20% carbon tetrachloride (CCl₄) corn oil solution (50 µL) was given to mice in the liver injury model group, 24 hours after injection, the model was established, while the control group received 0% CCl₄ corn oil solution (50 µL) (n=6 for each group). Additionally, doses of 8 mg/kg and 1 mg/kg of free ICG were injected intravenously (i.v.) (n=3 in each group). Fluorescence was imaged in vivo using an NIR fluorescence imaging system at different time points (1, 2, 4, 8, 12, 24, 48, and 72 h) after injection.

Results

The absolute fluorescence intensity of mice in the liver injury model group was stronger than that in the control group. Mice in the liver injury model group had the same clearance rate of ICG from the tumor as normal mice. However, the background clearance rate was slower than that of normal mice, which prolonged the optimal tumor to background ratio (TBR) time. Correlation analysis was also used to determine which preoperative liver function parameters were most correlated with hepatic ICG clearance.

Conclusions

Liver injury does not significantly affect the maximum TBR, but prolongs the optimal TBR time, and at the same time, a wider and more stable surgical window will appear. This study showed that a prolonged surgical start time is feasible according to preoperative liver function testing using NIR fluorescence imaging technology.

Targeted Intraoperative Molecular Imaging for Localizing Nonpalpable Tumors and Quantifying Resection Margin Distances

Importance

Complete (R0) resection is the dominant prognostic factor for survival across solid tumor types. Achieving adequate tumor clearance with appropriate margins is particularly difficult in nonpalpable tumors or in situ disease. Previous methods to address this problem have proven time consumptive, impractical, or ineffective.

Objective

To assess the capability of intraoperative molecular imaging (IMI), a novel technology using a fluorescent tracer targeted to malignant cells, to localize visually occult, nonpalpable tumors and quantify margin distances during resection.

Design, Setting, and Participants

This nonrandomized open-label trial of IMI using a folate receptor-targeted fluorescent tracer enrolled patients between May 2017 and June 2020 at a single referral center. Eligible patients included those with a small (T1) lung lesion suspicious for malignant neoplasms and with radiographic features suggestive of a nonpalpable lesion.

Interventions

Patients were preoperatively infused with a folate receptor-targeted near-infrared tracer. Intraoperatively, surgeons used thoracoscopic visualization and palpation to identify lesions. IMI was performed to detect the lesion in situ, and lesions were imaged ex vivo. Margins were assessed by IMI before comparison with those reported on final histopathologic analysis.

Main Outcomes and Measures

The main outcomes were whether IMI could (1) localize nonpalpable lung lesions in situ and (2) quantify margin distance with comparison with final pathology as the criterion standard. Patient demographic information and lesion characteristics were prospectively recorded.

Results

Of 40 patients, 26 (65%) were female, and the median (interquartile range) age was 66.5 (62-72) years. Conventional surgical methods localized 22 of 40 lesions (55%), while IMI localized 36 of 40 (90%). Of 18 nonpalpable lesions, 15 (83.3%) were identified by IMI. Both palpable and nonpalpable lesions demonstrated mean signal-to-background ratio more than 2. An IMI margin was able to be calculated for 39 of 40 patients (95%). IMI margins were nearly identical to margins reported on final pathology (R2 = 0.9593), with median (interquartile range) difference of 1.3 (0.7-2.0) mm. IMI detected 2 margins in nonpalpable tumors that were clinically unacceptable and would have had a high probability of recurrence.

Conclusions and Relevance

To our knowledge, this study presents the first clinical use of IMI for nonpalpable tumors and provides proof of principle for the utility of IMI across the field of surgical oncology in identifying occult disease and tumor-positive margins.

Introducing Fluorescence-Guided Surgery for Pediatric Ewing, Osteo-, and Rhabdomyosarcomas: A Literature Review

Sarcomas are a rare heterogeneous group of malignant neoplasms of mesenchymal origin which represent approximately 13% of all cancers in pediatric patients. The most prevalent pediatric bone sarcomas are osteosarcoma (OS) and Ewing sarcoma (ES). Rhabdomyosarcoma (RMS) is the most frequently occurring pediatric soft tissue sarcoma. The median age of OS and ES is approximately 17 years, so this disease is also commonly seen in adults while non-pleiomorphic RMS is rare in the adult population. The mainstay of all treatment regimens is multimodal treatment containing chemotherapy, surgical resection, and sometimes (neo)adjuvant radiotherapy. A clear resection margin improves both local control and overall survival and should be the goal during surgery with a curative intent. Real-time intraoperative fluorescence-guided imaging could facilitate complete resections by visualizing tumor tissue during surgery. This review evaluates whether non-targeted and targeted fluorescence-guided surgery (FGS) could be beneficial for pediatric OS, ES, and RMS patients. Necessities for clinical implementation, current literature, and the positive as well as negative aspects of non-targeted FGS using the NIR dye Indocyanine Green (ICG) were evaluated. In addition, we provide an overview of targets that could potentially be used for FGS in OS, ES, and RMS. Then, due to the time- and cost-efficient translational perspective, we elaborate on the use of antibody-based tracers as well as their disadvantages and alternatives. Finally, we conclude with recommendations for the experiments needed before FGS can be implemented for pediatric OS, ES, and RMS patients.

A pilot study of near-infrared fluorescence guided surgery for primary tumor localization and lymph node mapping in colorectal cancer

Background

This pilot study aimed to evaluate the feasibility of near-infrared fluorescence imaging for primary tumor localization, lymph node mapping, and metastatic lymph node detection in colorectal cancer (CRC) using indocyanine green (ICG).

Methods

A total of 11 patients with CRC were prospectively enrolled. ICG (25 mg dissolved in 30 mL sterile water) was intravenously injected preoperatively, and the fluorescence intensity of the primary tumor, lymph nodes, and normal tissues, as well as the signal-to-background ratio (SBR) and contrast-to-noise ratio (CNR) were measured at 0.5, 1, 2, 4, and 24 h after ICG injection.

Results

The primary tumor could be located intraoperatively, and the tumor boundary was clear at 2–4 h. There was good contrast in the fluorescence intensity between tumor and normal tissues (SBR =2.11±0.36, CNR =8.74±0.35). The lymph node detection rate was 95% (38/40), and the SBR threshold of lymph nodes was 1.13.

Conclusions

This pilot study showed that primary tumor localization and lymph node mapping in CRC is feasible using near-infrared fluorescence imaging technology, though metastatic lymph nodes cannot be discriminated from benign ones. In addition, cancer nodules missed by both white light mode and palpation by the surgeon were unexpectedly found, resulting in a change in the surgical prognosis in 9.1% (1/11) of patients.

Evaluation of Intraoperative Near-Infrared Fluorescence Visualization of the Lung Tumor Margin With Indocyanine Green Inhalation

Importance

Identification of the tumor margin during surgery is important for precise minimal resection of lung tumors. Intravenous injection of indocyanine green (ICG) has several limitations when used for intraoperative visualization of lung cancer.

Objectives

To describe a technique for intraoperative visualization of lung tumor margin using ICG inhalation and evaluate the clinical applicability of the technique in mouse and rabbit lung tumor models as well as lung specimens of patients with lung tumors.

Design, Setting, and Participants

In lung tumor models of both mice and rabbits, the distribution of inhaled ICG in the lung tumor margin was investigated in vivo and ex vivo using a near-infrared imaging system. Lung tumor margin detection via inhalation of ICG was evaluated by comparing the results obtained with those of the intravenous injection method (n = 32, each time point for 4 mice). Based on preclinical data, use of ICG inhalation to help detect the tumor margin in patients with lung cancer was also evaluated (n = 6). This diagnostic study was conducted from May 31, 2017, to March 30, 2019.

Main Outcomes and Measures

The use of tumor margin detection by inhaled ICG was evaluated by comparing the inhaled formulation with intravenous administration of ICG.

Results

From 10 minutes after inhalation of ICG to 24 hours, the distribution of ICG in the lungs was significantly higher than that in other organs (signal to noise ratio in the lungs: 39 486.4; interquartile range [IQR], 36 983.74-43 592.5). Ex vivo and histologic analysis showed that, in both lung tumor models, inhaled ICG was observed throughout the healthy lung tissue but was rarely found in tumor tissue. The difference in the fluorescent signal between healthy and tumor lung tissues was associated with the mechanical airway obstruction caused by the tumor and with alveolar macrophage uptake of the inhaled ICG in healthy tissues. Inhalation at a 20-fold lower dose of ICG had a 2-fold higher efficiency for tumor margin detection than did the intravenous injection (2.9; IQR, 2.7-3.2; P < .001).

Conclusions and Relevance

The results of this study suggest that lung-specific inhalation delivery of ICG is feasible and may be useful for the intraoperative visualization of lung tumor margin in clinical practice.

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.

A Surgical Approach to Pulmonary Metastasis in Children

Decisions regarding the role of surgery in pulmonary metastasis need to take into account histology and biology of the cancer. Response to chemotherapy and radiotherapy, balanced with toxicities, factors into decisions about metastasectomy. The less sensitive the tumor is to adjuvant therapy, the more likely that metastasectomy may be beneficial. Broad principles include the following: the aims of resection are localized resections with clear margins, with the aim of preserving adequate lung volume; unnecessary toxic therapy sometimes is avoided with accurate diagnosis; tumor type is of utmost importance; and number of metastases and the disease-free interval are not contraindications to metastasectomy.

Indocyanine Green-Guided Pediatric Tumor Resection: Approach, Utility, and Challenges

Incomplete tumor resection increases the risk of local recurrence. However, the standard of care approach to distinguishing tumor tissue is less than optimal, as it depends on a conglomeration of preoperative imaging and visual and tactile indicators in real time. This approach is associated with a significant risk of inadequate resection; therefore, a novel approach that delineates the accurate intraoperative definition of pediatric tumors is urgently needed. To date, there is no reliable method for the intraoperative assessment of tumor extent and real-time differentiation between tumor- involved tissues and tumor-free tissues. Use of intraoperative frozen sections is challenging, time consuming, and covers a small surface area. Increased vascular permeability and impaired lymphatic drainage in the tumor microenvironment leads to an enhanced permeability and retention effect of small molecules. ICG is a fluorescent dye that when administered intravenously accumulates passively in the tumor because of EPR, thereby providing some tumor contrast for intraoperative real-time tumor recognition. Preclinical and clinical studies suggest that the tumor-to-background fluorescence ratio is optimized when imaging is obtained 24 h after dye injection, and many studies suggest using a high dose of ICG to optimize dye retention in the tumor tissue. However, in childhood cancers, little is known about the ideal dosing, applications, and challenges of ICG-guided tumor resection. This retrospective study examines the feasibility of ICG-guided tumor resection in common childhood solid tumors such as neuroblastoma, sarcomas, hepatic tumors, pulmonary metastases, and other rare tumors. Pediatric dosing and challenges related to the optimization of tumor-to-background ratio are also examined.

Molecularly targeted photothermal ablation improves tumor specificity and immune modulation in a rat model of hepatocellular carcinoma

Thermal ablation is a standard therapy for patients with hepatocellular carcinoma (HCC). Contemporary ablation devices are imperfect, as they lack tumor specificity. An ideal ablation modality would generate thermal energy only within tumoral tissue. Furthermore, as hyperthermia is known to influence tumor immunity, such a tumor-specific ablation modality may have the ability to favorably modulate the tumor immune landscape. Here we show a clinically relevant thermal ablation modality that generates tumor-specific hyperthermia, termed molecularly targeted photothermal ablation (MTPA), that is based upon the excellent localization of indocyanine green to HCC. In a syngeneic rat model, we demonstrate the tumor-specific hyperthermia generated by MTPA. We also show through spatial and transcriptomic profiling techniques that MTPA favorably modulates the intratumoral myeloid population towards tumor immunogenicity and diminishes the systemic release of oncogenic cytokines relative to conventional ablation modalities.

Nina Muñoz et al. present a novel thermal ablation technique, termed molecularly targeted photothermal ablation (MTPA) that generates hyperthermia specifically within tumor tissue in a clinically-relevant rat model of liver cancer. They further show that MTPA modulates the intratumoral immune profile toward stronger tumor immunogenicity while reducing the release of oncogenic cytokines relative to conventional ablation techniques.

Evaluation of Diagnostic Accuracy Following the Coadministration of Delta-Aminolevulinic Acid and Second Window Indocyanine Green in Rodent and Human Glioblastomas

PURPOSE

Fluorescence-guided-surgery offers intraoperative visualization of neoplastic tissue. Delta-aminolevulinic acid (5-ALA), which targets enzymatic abnormality in neoplastic cells, is the only approved agent for fluorescence-guided neurosurgery. More recently, we described Second Window Indocyanine Green (SWIG) which targets neoplastic tissue through enhanced vascular permeability. We hypothesized that SWIG would demonstrate similar clinical utility in identification of high-grade gliomas compared with 5-ALA.

PROCEDURES

Female C57/BL6 and nude/athymic mice underwent intracranial implantation of 300,000 GL261 and U87 cells, respectively. Tumor-bearing mice were euthanized after administration of 5-ALA (200 mg/kg intraperitoneal) and SWIG (5 mg/kg intravenous). Brain sections were imaged for protoporphyrin-IX and ICG fluorescence. Fluorescence and H&E images were registered using semi-automatic scripts for analysis. Human subjects with HGG were administered SWIG (2.5 mg/kg intravenous) and 5-ALA (20 mg/kg oral). Intraoperatively, tumors were imaged for ICG and protoporphyrin-IX fluorescence.

RESULTS

In non-necrotic tumors, 5-ALA and SWIG demonstrated 90.2 % and 89.2 % tumor accuracy (p value = 0.52) in U87 tumors and 88.1 % and 87.7 % accuracy (p value = 0.83) in GL261 tumors. The most distinct difference between 5-ALA and SWIG distribution was seen in areas of tumor-associated necrosis, which often showed weak/no protoporphyrin-IX fluorescence, but strong SWIG fluorescence. In twenty biopsy specimens from four subjects with HGG, SWIG demonstrated 100 % accuracy, while 5-ALA demonstrated 75-85 % accuracy; there was 90 % concordance between SWIG and 5-ALA fluorescence.

CONCLUSION

Our results provide the first direct comparison of the diagnostic utility of SWIG vs 5-ALA in both rodent and human HGG. Given the broader clinical utility of SWIG compared with 5-ALA, our data supports the use of SWIG in tumor surgery to improve the extent of safe resections.

CLINICAL TRIAL

NCT02710240 (US National Library of Medicine Registry; https://www.clinicaltrials.gov/ct2/show/NCT02710240?id=NCT02710240&draw=2&rank=1 ).

The safety and feasibility of intraoperative near-infrared fluorescence imaging with indocyanine green in thoracoscopic sympathectomy for primary palmar hyperhidrosis

Background

We investigated the safety and feasibility of intraoperative near‐infrared (NIR) imaging using indocyanine green (ICG) during sympathectomy in the management of primary palmar hyperhidrosis (PPH).

Methods

We performed a retrospective review of 142 patients (ICG group) who underwent endoscopic thoracic sympathectomy (ETS) between February 2018 and April 2019. All patients received a 5 mg/kg infusion of ICG 24 hours preoperatively. The vital signs before and after ICG injection and adverse reactions were recorded. Meanwhile, 498 patients (Non‐ICG group) who underwent ETS by normal thoracoscopy during August 2017 to April 2019 were also reviewed to compare the abnormal white blood cell (WBC) counts, alanine transaminase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN), and creatinine (Cr) levels before and after operation between two groups.

Results

For ICG group, the vital signs including body temperature, heart rate and blood pressure before and after ICG injection were stable. There was no significant difference in the abnormal WBC counts, ALT, AST, BUN, and Cr levels before and after operation between two groups. Only one patient had mild adverse reaction (0.7%) after ICG injection. The visibility rate of all sympathetic ganglions was 96.7% (1369/1415). The visibility rate from T1 to T5 was 98.23% (278/283), 98.23% (278/283), 97.17% (275/283), 95.76% (271/283), and 94.35% (267/283), respectively. There was no significant difference in the visibility rate with regard to age, gender, height, weight, body mass index, and PPH grade.

Conclusions

NIR fluorescence imaging with ICG for identifying sympathetic ganglions is relatively safe and feasible.

Key points

• Significant findings of the study.

NIR fluorescence imaging with ICG for identifying sympathetic ganglions is relatively safe and feasible.

• What this study adds.

This technology may take the place of the rib‐oriented method as standard practice for the precise localization of sympathetic ganglions, and may improve the effect of sympathectomies.

Surgical Management of Hepatoblastoma and Recent Advances

Hepatoblastoma is the most common childhood liver malignancy. The management of hepatoblastoma requires multidisciplinary efforts. The five-year overall survival is approximately 80% in developed countries. Surgery remains the mainstay of treatment for hepatoblastoma, and meticulous techniques must be employed to ensure safe and effective local control surgeries. Additionally, there have been several advances from both pediatric and adult literature in the way liver tumor surgery is performed. In this review, we highlight important aspects of liver surgery for hepatoblastoma, the management of metastatic disease, and the most current technical advances in performing these procedures in a safe and effective manner.

Review of clinical trials in intraoperative molecular imaging during cancer surgery

Most solid cancers are treated by surgical resections to reduce the burden of disease. Surgeons often face the challenge of detecting small areas of residual neoplasm after resection or finding small primary tumors for the initial resection. Intraoperative molecular imaging (IMI) is an emerging technology with the potential to dramatically improve cancer surgery operations by allowing surgeons to better visualize areas of neoplasm using fluorescence imaging. Over the last two years, two molecular optical contrast agents received U.S. Food and Drug Administration approval, and several more drugs are now on the horizon. Thus a conference was organized at the University of Pennsylvania to bring together oncologic surgeons from different specialties to discuss the current clinical status of IMI trials with a specific focus on phase 2 and phase 3 studies. In addition, phase 1 and experimental trials were also discussed briefly, to highlight other novel techniques. Our review summarizes the discussions from the conference and delves into the types of cancers discussed, different contrast agents in human trials, and the clinical value being studied.

Evaluation of Aminolevulinic Acid-Derived Tumor Fluorescence Yields Disparate Results in Murine and Spontaneous Large Animal Models of Lung Cancer

Fluorescence guided surgery is an emerging technology that may improve accuracy of pulmonary resection for non-small cell lung cancer (NSCLC). Herein we explore optical imaging for NSCLC surgery using the well-studied protoporphyrin IX (PPIX)/5-aminiolevulinic acid (5-ALA) system. More specifically, we evaluate fluorescent patterns observed when using (1) commonly utilized in vitro and murine NSCLC models and with (2) spontaneous canine NSCLCs, which closely mimic human disease. Using flow cytometry and fluorescent microscopy, we confirmed that NSCLC models fluoresce after exposure to 5-ALA in vitro. High levels of fluorescence were similarly observed in murine tumors within 2 hours of systemic 5-ALA delivery. When evaluating this approach in spontaneous canine NSCLC, tumor fluorescence was observed in 6 of 7 canines. Tumor fluorescence, however, was heterogenous owing to intratumoral variations in cellularity and necrosis. Margin and lymph node detection was inaccurate. These data demonstrate the importance of incorporating reliable cancer models into preclinical evaluations of optical agents. Utilization of spontaneous large animal models of cancer may further provide an important intermediate in the path to human translation of optical contrast agents.

Detection and Differentiation of Breast Cancer Sub-Types using a cPLA2α Activatable Fluorophore

Cytosolic phospholipase A2α (cPLA2α) has been shown to be elevated in breast cancer and is a potential biomarker in the differentiation of molecular sub-types. Using a cPLA2α activatable fluorophore, DDAO arachidonate, we explore its ability to function as a contrast agent in fluorescence-guided surgery. In cell lines ranging in cPLA2α expression and representing varying breast cancer sub-types, we show DDAO arachidonate activates with a high correlation to cPLA2α expression level. Using a control probe, DDAO palmitate, in addition to cPLA2α inhibition and genetic knockdown, we show that this activation is a result of cPLA2α activity. In mouse models, using an ex vivo tumor painting technique, we show that DDAO arachidonate activates to a high degree in basal-like versus luminal-like breast tumors and healthy mammary tissue. Finally, we show that using an in vivo model, orthotopic basal-like tumors give significantly high probe activation compared to healthy mammary fat pads and surrounding tissue. Together we conclude that cPLA2α activatable fluorophores such as DDAO arachidonate may serve as a useful contrast agent for the visualization of tumor margins in the fluorescence-guided surgery of basal-like breast cancer.

A clinical trial of intraoperative near-infrared imaging to assess tumor extent and identify residual disease during anterior mediastinal tumor resection

BACKGROUND

The management of most solid tumors of the anterior mediastinum involves complete resection. Because of their location near mediastinal structures, wide resection is not possible; therefore, surgeons must use subjective visual and tactile cues to determine disease extent. This clinical trial explored intraoperative near-infrared (NIR) imaging as an approach to improving tumor delineation during mediastinal tumor resection.

METHODS

Twenty-five subjects with anterior mediastinal lesions suspicious for malignancy were enrolled in an open-label feasibility trial. Subjects were administered indocyanine green (ICG) at a dose of 5 mg/kg, 24 hours before resection (via a technique called TumorGlow). The NIR imaging systems included Artemis (Quest, Middenmeer, the Netherlands) and Iridium (VisionSense Corp, Philadelphia, Pennsylvania). Intratumoral ICG uptake was evaluated. The clinical value was determined via an assessment of the ability of NIR imaging to detect phrenic nerve involvement or incomplete resection. Clinical and histopathologic variables were analyzed to determine predictors of tumor fluorescence.

RESULTS

No drug-related toxicity was observed. Optical imaging added a mean of 10 minutes to case duration. Among the subjects with solid tumors, 19 of 20 accumulated ICG. Fluorescent tumors included thymomas (n = 13), thymic carcinomas (n = 4), and liposarcomas (n = 2). NIR feedback improved phrenic nerve dissection (n = 4) and identified residual disease (n = 2). There were no false-positives or false-negatives. ICG preferentially accumulated in solid tumors; this was independent of clinical and pathologic variables.

CONCLUSIONS

NIR imaging for anterior mediastinal neoplasms is safe and feasible. This technology may provide a real-time tool capable of determining tumor extent and specifically identify phrenic nerve involvement and residual disease.

Kinetics of indocyanine green: Optimizing tumor to normal tissue fluorescence in image-guided oral cancer surgery applications

BACKGROUND

The study aimed to define indocyanine green (ICG) kinetics to determine the optimal ICG dose and surgical time for near-infrared fluorescence-guided oral cancer surgery.

METHODS

Spectrometer and grayscale digital imaging were used to quantify the ICG kinetics in 12 patients with oral cancer. The fluorescence intensity and signal-to-background ratio (SBR) of tumor and normal tissue were tested at 1, 6, and 24 hours after ICG injection.

RESULTS

The greatest contrast in the fluorescence intensity between tumor and normal tissue was observed at 6 hours (P < .01), and of three dose groups (0.5, 0.75, and 1.0 mg/kg), 0.75 mg/kg showed the highest SBR (2.06 ± 0.23) after ICG injection.

CONCLUSIONS

Fluorescence quantification based on spectrometry and grayscale imaging could be effective in determining the optimal ICG dose and surgical time after ICG injection in this cohort of patients with oral cancer.

Near-infrared intraoperative imaging for minimally invasive pulmonary metastasectomy for sarcomas

BACKGROUND

Complete pulmonary metastasectomy for sarcoma metastases provides patients an opportunity for long-term survival and possible cure. Intraoperative localization of preoperatively identified metastases and identification of occult lesions can be challenging. In this trial, we evaluated the efficacy of near-infrared (NIR) intraoperative imaging using second window indocyanine green during metastasectomy to identify known metastases and to detect occult nodules.

METHODS

Thirty patients with pulmonary nodules suspicious for sarcoma metastases were enrolled in an open-label, feasibility study (NCT02280954). All patients received intravenous indocyanine green (5 mg/kg) 24 hours before metastasectomy. Patients 1 through 10 (cohort 1) underwent metastasectomy via thoracotomy to assess fluorescence patterns of nodules detected by traditional methods (preoperative imaging and intraoperative visualization/bimanual palpation). After confirming reliability within cohort 1, patients 11 through 30 (cohort 2) underwent video-assisted thoracic surgery metastasectomy with NIR imaging.

RESULTS

In cohort 1, 14 out of 16 preoperatively identified pulmonary metastases (87.5%) displayed tumor fluorescence. Nonfluorescent metastases were deeper than fluorescent metastases (2.1 cm vs 1.3 cm; P = .03). Five out of 5 metastases identified during thoracotomy displayed fluorescence. NIR imaging identified 3 additional occult lesions in this cohort. In cohort 2, 33 out of 37 known pulmonary metastases (89.1%) displayed fluorescence. Nonfluorescent tumors were deeper than 2.0 cm (P = .007). NIR imaging identified 24 additional occult lesions. Of 24 occult lesions, 21 (87.5%) were confirmed metastases and the remaining 3 nodules were lymphoid aggregates.

CONCLUSIONS

NIR intraoperative imaging with indocyanine green (5 mg/kg and 24 hours before surgery) localizes known sarcoma pulmonary metastases and identifies otherwise occult lesions. This approach may be a useful intraoperative adjunct to improve metastasectomy.

Optimization of Second Window Indocyanine Green for Intraoperative Near-Infrared Imaging of Thoracic Malignancy

BACKGROUND

Near-infrared (NIR) imaging using the second time window of indocyanine green (ICG) allows localization of pulmonary, pleural, and mediastinal malignancies during surgery. Based on empirical evidence, we hypothesized that different histologic tumor types fluoresce optimally at different ICG doses.

STUDY DESIGN

Patients with thoracic tumors biopsy-proven or suspicious for malignancy were enrolled in an NIR imaging clinical trial. Patients received a range of ICG doses 1 day before surgery: 1 mg/kg (n = 8), 2 mg/kg (n = 8), 3 mg/kg (n = 13), 4 mg/kg (n = 8), and 5 mg/kg (n = 8). Intraoperatively, NIR imaging was performed. The endpoint was to identify the highest tumor-to-background fluorescence ratio (TBR) for each tumor type at each dose. Final pathology confirmed tumor histology.

RESULTS

Of 45 patients, 41 had malignancies (18 non-small cell lung cancers [NSCLC], 3 pulmonary neuroendocrine tumors, 13 thoracic metastases, 4 thymomas, 3 mesotheliomas). At doses of 4 to 5 mg/kg, the TBR from primary NSCLC vs other malignancies was no different (2.70 vs 3.21, p = 1.00). At doses of 1 to 3 mg/kg, the TBR was greater for the NSCLCs (3.19 vs 1.49, p = 0.0006). Background fluorescence from the heart or ribs was observed in 1 of 16 cases at 1 to 2 mg/kg, 5 of 13 cases at 3 mg/kg, and 14 of 16 cases at 4 to 5 mg/kg; this was a major determinant of dose optimization.

CONCLUSIONS

This is the first study to demonstrate that the optimal NIR contrast agent dose varies by tumor histology. Lower dose ICG (2 to 3 mg/kg) is superior for nonprimary lung cancers, and high dose ICG (4 to 5 mg/kg) is superior for lung cancers. This will have major implications as more intraoperative imaging trials surface in other specialties, will significantly reduce costs and may facilitate wider application.

Intraoperative fluorescence imaging in thoracic surgery

Intraoperative fluorescence imaging (IFI) can improve real-time identification of cancer cells during an operation. Phase I clinical trials in thoracic surgery have demonstrated that IFI with second window indocyanine green (TumorGlow^® ) can identify subcentimeter pulmonary nodules, anterior mediastinal masses, and mesothelioma, while the use of a folate receptor-targeted near-infrared agent, OTL38, can improve the specificity for diagnosing tumors with folate receptor expression. Here, we review the existing preclinical and clinical data on IFI in thoracic surgery.

A Clinical Trial of TumorGlow to Identify Residual Disease During Pleurectomy and Decortication

BACKGROUND

Macroscopic complete resection can improve survival in a select group of patients with malignant pleural mesothelioma. During resection, differentiating residual tumor from inflammation or scar can be challenging. This trial evaluated near-infrared (NIR) intraoperative imaging using TumorGlow (a novel NIR imaging approach utilizing high-dose indocyanine green and delayed imaging) technology to improve detection of macroscopic residual disease.

METHODS

Twenty subjects were enrolled in an open-label clinical trial of NIR intraoperative imaging with TumorGlow (Indocyanine Green for Solid Tumors [NCT02280954]). Twenty-four hours before pleural biopsy or pleurectomy and decortication (P/D), patients received intravenous indocyanine green. All specimens identified during standard-of-care surgical resection and with NIR imaging underwent histopathologic profiling and correlative microscopic fluorescent tomographic evaluation. For subjects undergoing P/D (n = 13), the hemithorax was evaluated with NIR imaging during P/D to assess for residual disease. When possible, additional fluorescent lesions were resected.

RESULTS

Of 203 resected specimens submitted for evaluation, indocyanine green accumulated within 113 of 113 of resected mesothelioma specimens, with a mean signal-to-background fluorescence ratio of 3.1 (SD, 2.2 to 4.8). The mean signal-to-background fluorescence ratio of benign tissues was 2.2 (SD, 1.4 to 2.4), which was significantly lower than in malignant specimens (p = 0.001). NIR imaging identified occult macroscopic residual disease in 10 of 13 subjects. A median of 5.6 resectable residual deposits per patient (range, 0 to 11 deposits per patient), with a mean size of 0.3 cm (range, 0.1 to 1.5 cm), were identified.

CONCLUSIONS

TumorGlow for malignant pleural mesothelioma is safe and feasible. Excellent sensitivity allows for to reliable detection of macroscopic residual disease during cytoreductive surgical procedures.

Near-Infrared Intraoperative Imaging Can Successfully Identify Malignant Pleural Mesothelioma After Neoadjuvant Chemotherapy

Malignant pleural mesothelioma is a deadly disease. Complete surgical resection provides patients with the best opportunity for long-term survival. Unfortunately, identification of disease during resection can be challenging. In this report, we describe successful intraoperative utilization of the near-infrared imaging agent, indocyanine green, to help the surgeon identify malignant disease in a patient with malignant pleural mesothelioma who had previously received neoadjuvant chemotherapy. This technology may ultimately enhance the thoracic surgeon's ability to identify small disease deposits at the time of resection.

An open label trial of folate receptor-targeted intraoperative molecular imaging to localize pulmonary squamous cell carcinomas

BACKGROUND

Clinical applicability of folate receptor-targeted intraoperative molecular imaging (FR-IMI) has been established for surgically resectable pulmonary adenocarcinoma. A role for FR-IMI in other lung cancer histologies has not been studied. In this study, we evaluate feasibility of FR-IMI in patients undergoing pulmonary resection for squamous cell carcinomas (SCCs).

METHODS

In a human clinical trial (NCT02602119), twelve subjects with pulmonary SCCs underwent FR-IMI with a near-infrared contrast agent that targets the folate receptor-α (FRα), OTL38. Near-infrared signal from tumors and benign lung was quantified to calculate tumor-to-background ratios (TBR). Folate receptor-alpha expression was characterized, and histopathologic correlative analyses were performed to evaluate patterns of OTL38 accumulation. An exploratory analysis was performed to determine patient and histopathologic variables that predict tumor fluorescence.

RESULTS

9 of 13 SCCs (in 9 of 12 of subjects) displayed intraoperative fluorescence upon NIR evaluation (median TBR, 3.9). OTL38 accumulated within SCCs in a FRα-dependent manner. FR-IMI was reliable in localizing nodules as small as 1.1 cm, and prevented conversion to thoracotomy for nodule localization in three subjects. Upon evaluation of patient and histopathologic variables, in situ fluorescence was associated with distance from the pleural surface, and was independent of alternative variables including tumor size and metabolic activity.

CONCLUSIONS

This work demonstrates that FR-IMI is potentially feasible in 70% of SCC patients, and that molecular imaging can improve localization during minimally invasive pulmonary resection. These findings complement previous data demonstrating that ∼98% of pulmonary adenocarcinomas are localized during FR-IMI and suggest broad applicability for NSCLC patients undergoing resection.

A Phase I Clinical Trial of Targeted Intraoperative Molecular Imaging for Pulmonary Adenocarcinomas

BACKGROUND

Intraoperative identification of pulmonary nodules, particularly small lesions, can be challenging. We hypothesize that folate receptor-targeted intraoperative molecular imagining can be safe and improve localization of pulmonary nodules during resection.

METHODS

Twenty subjects with biopsy-proven pulmonary adenocarcinomas were enrolled in a phase I clinical trial to test the safety and feasibility of OTL38, a novel folate receptor-α (FRα) targeted optical contrast agent. During resection, tumors were imaged in situ and ex vivo and fluorescence was quantified. Resected specimens were analyzed to confirm diagnosis, and immunohistochemistry was utilized to quantify FRα expression. A multivariate analysis using clinical and tumor data was performed to determine variables impacting tumor fluorescence.

RESULTS

Of the 20 subjects, three grade I adverse events were observed: all transient nausea/abdominal pain. All symptoms resolved after completing the infusion. Sixteen of 20 subjects (80%) had tumors with in situ fluorescence with a mean tumor-to-background fluorescence level of 2.9 (interquartile range, 2.1 to 4.2). The remaining 4 subjects' tumors fluoresced ex vivo. In situ fluorescence was dependent on depth from the pleural surface. Four subcentimeter nodules not identified on preoperative imaging were detected with intraoperative imaging.

CONCLUSIONS

This phase I trial provides preliminary evidence suggesting that folate receptor-targeted molecular imaging with OTL38 is safe, with tolerable grade I toxicity. These data also suggest that OTL38 accumulates in known lung cancers and may improve identification of synchronous malignancies. Our group is initiating a five-center, phase II study to better understand the clinical implications of intraoperative molecular imaging using OTL38.

Quantitative Primary Tumor Indocyanine Green Measurements Predict Osteosarcoma Metastatic Lung Burden in a Mouse Model

BACKGROUND

Current preclinical osteosarcoma (OS) models largely focus on quantifying primary tumor burden. However, most fatalities from OS are caused by metastatic disease. The quantification of metastatic OS currently relies on CT, which is limited by motion artifact, requires intravenous contrast, and can be technically demanding in the preclinical setting. We describe the ability for indocyanine green (ICG) fluorescence angiography to quantify primary and metastatic OS in a previously validated orthotopic, immunocompetent mouse model.

QUESTIONS/PURPOSES

(1) Can near-infrared ICG fluorescence be used to attach a comparable, quantitative value to the primary OS tumor in our experimental mouse model? (2) Will primary tumor fluorescence differ in mice that go on to develop metastatic lung disease? (3) Does primary tumor fluorescence correlate with tumor volume measured with CT?

METHODS

Six groups of 4- to 6-week-old immunocompetent Balb/c mice (n = 6 per group) received paraphyseal injections into their left hindlimb proximal tibia consisting of variable numbers of K7M2 mouse OS cells. A hindlimb transfemoral amputation was performed 4 weeks after injection with euthanasia and lung extraction performed 10 weeks after injection. Histologic examination of lung and primary tumor specimens confirmed ICG localization only within the tumor bed.

RESULTS

Mice with visible or palpable tumor growth had greater hindlimb fluorescence (3.5 ± 2.3 arbitrary perfusion units [APU], defined as the fluorescence pixel return normalized by the detector) compared with those with a negative examination (0.71 ± 0.38 APU, -2.7 ± 0.5 mean difference, 95% confidence interval -3.7 to -1.8, p < 0.001). A strong linear trend (r = 0.81, p < 0.01) was observed between primary tumor and lung fluorescence, suggesting that quantitative ICG tumor fluorescence is directly related to eventual metastatic burden. We did not find a correlation (r = 0.04, p = 0.45) between normalized primary tumor fluorescence and CT volumetric measurements.

CONCLUSIONS

We demonstrate a novel methodology for quantifying primary and metastatic OS in a previously validated, immunocompetent, orthotopic mouse model. Quantitative fluorescence of the primary tumor with ICG angiography is linearly related to metastatic burden, a relationship that does not exist with respect to clinical tumor size. This highlights the potential utility of ICG near-infrared fluorescence imaging as a valuable preclinical proof-of-concept modality. Future experimental work will use this model to evaluate the efficacy of novel OS small molecule inhibitors.

CLINICAL RELEVANCE

Given the histologic localization of ICG to only the tumor bed, we envision the clinical use of ICG angiography as an intraoperative margin and tumor detector. Such a tool may be used as an alternative to intraoperative histology to confirm negative primary tumor margins or as a valuable tool for debulking surgeries in vulnerable anatomic locations. Because we have demonstrated the successful preservation of ICG in frozen tumor samples, future work will focus on blinded validation of this modality in observational human trials, comparing the ICG fluorescence of harvested tissue samples with fresh frozen pathology.

Image-guided surgery in cancer: A strategy to reduce incidence of positive surgical margins

Primary treatment for many solid cancers includes surgical excision or radiation therapy, with or without the use of adjuvant therapy. This can include the addition of radiation and chemotherapy after primary surgical therapy, or the addition of chemotherapy and salvage surgery to primary radiation therapy. Both primary therapies, surgery and radiation, require precise anatomic localization of tumor. If tumor is not targeted adequately with initial treatment, disease recurrence may ensue, and if targeting is too broad, unnecessary morbidity may occur to nearby structures or remaining normal tissue. Fluorescence imaging using intraoperative contrast agents is a rapidly growing field for improving visualization in cancer surgery to facilitate resection in order to obtain negative margins. There are multiple strategies for tumor visualization based on antibodies against surface markers or ligands for receptors preferentially expressed in cancer. In this article, we review the incidence and clinical implications of positive surgical margins for some of the most common solid tumors. Within this context, we present the ongoing clinical and preclinical studies focused on the use of intraoperative contrast agents to improve surgical margins. This article is categorized under: Laboratory Methods and Technologies > Imaging.

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.

Long-term outcomes after near-infrared sentinel lymph node mapping in non-small cell lung cancer

OBJECTIVE

To report the first analysis of long-term outcomes using near-infrared (NIR) image-guided sentinel lymph node (SLN) mapping in non-small cell lung cancer (NSCLC).

METHODS

Retrospective analysis of patients with NSCLC enrolled in 2 prospective phase 1 NIR-guided SLN mapping trials, including an indocyanine green (ICG) dose-escalation trial, was performed. All patients underwent NIR imaging for SLN identification followed by multistation mediastinal lymph node sampling (MLNS) and pathologic assessment. Disease-free (DFS) and overall survival (OS) were compared between patients with NIR⁺ SLN (SLN group) and those without (non-SLN group).

RESULTS

SLN detection, recurrence, DFS, and OS were assessed in 42 patients with NSCLC who underwent intraoperative peritumoral ICG injection, NIR imaging, and MLNS. NIR⁺ SLNs were identified in 23 patients (SLN group), whereas SLNs were not identified in 19 patients enrolled before ICG dose and camera optimization (non-SLN group). Median follow-up was 44.5 months. Pathology from NIR⁺ SLNs was concordant with overall nodal status in all 23 patients. Sixteen patients with SLN were deemed pN0 and no recurrences were, whereas 4 of 15 pN0 non-SLN patients developed nodal or distant recurrent disease. Comparing SLN versus non-SLN pN0 patients, the probability of 5-year OS is 100% versus 70.0% (P = .062) and 5-year DFS is statistically significantly improved at 100% versus 66.1% (P = .036), respectively. Among the 11 pN+ patients, 7 were in the SLN group, with >40% showing metastases in the SLN alone.

CONCLUSIONS

Patients with pN0 SLNs showed favorable disease-free and overall survival. This preliminary review of NIR SLN mapping in NSCLC suggests that pN0 SLNs may better represent true N0 status. A larger clinical trial is planned to validate these findings.

Near-infrared intraoperative imaging during resection of an anterior mediastinal soft tissue sarcoma

Sarcomas are rare malignancies that are generally treated with multimodal therapy protocols incorporating complete local resection, chemotherapy and radiation. Unfortunately, even with this aggressive approach, local recurrences are common. Near-infrared intraoperative imaging is a novel technology that provides real-time visual feedback that can improve identification of disease during resection. The presented study describes utilization of a near-infrared agent (indocyanine green) during resection of an anterior mediastinal sarcoma. Real-time fluorescent feedback provided visual information that helped the surgeon during tumor localization, margin assessment and dissection from mediastinal structures. This rapidly evolving technology may prove useful in patients with primary sarcomas arising from other locations or with other mediastinal neoplasms.

Intraoperative Molecular Imaging Combined With Positron Emission Tomography Improves Surgical Management of Peripheral Malignant Pulmonary Nodules

OBJECTIVE

To determine if intraoperative molecular imaging (IMI) can improve detection of malignant pulmonary nodules.

BACKGROUND

18-Fluorodeoxyglucose positron emission tomography (PET) is commonly utilized in preoperative assessment of patients with solid malignancies; however, false negatives and false positives remain major limitations. Using patients with pulmonary nodules as a study model, we hypothesized that IMI with a folate receptor targeted near-infrared contrast agent (OTL38) can improve malignant pulmonary nodule identification when combined with PET.

METHODS

Fifty patients with pulmonary nodules with imaging features suspicious for malignancy underwent preoperative PET. Patients then received OTL38 before pulmonary resection. During resection, IMI was utilized to evaluate known pulmonary nodules and identify synchronous lesions. Tumor size, PET standardized uptake value, and IMI tumor-to-background ratios were compared for known and synchronous nodules via paired and unpaired t tests, when appropriate. Test characteristics of PET and IMI with OTL38 were compared.

RESULTS

IMI identified 56 of 59 (94.9%) malignant pulmonary nodules identified by preoperative imaging. IMI located an additional 9 malignant lesions not identified preoperatively. Nodules only detected by IMI were smaller than nodules detected preoperatively (0.5 vs 2.4 cm; P < 0.01), but displayed similar fluorescence (tumor-to-background ratio 3.3 and 3.1; P = 0.50). Sensitivity of IMI and PET were 95.6% and 73.5% (P = 0.001), respectively; and positive predictive values were 94.2% and 89.3%, respectively (P > 0.05). Additionally, utilization of IMI clinically upstaged 6 (12%) subjects and improved management of 15 (30%) subjects.

CONCLUSIONS

These data suggest that combining IMI with PET may provide superior oncologic outcomes for patients with resectable lung cancer.

Near-infrared Intraoperative Molecular Imaging Can Identify Metastatic Lymph Nodes in Prostate Cancer

OBJECTIVE

To propose a novel method to perform indocyanine green (ICG) based near-infrared (NIR) fluorescence imaging during pelvic lymph node dissection (PLND) for prostate cancer patients with lymph node metastasis (LNM).

MATERIALS AND METHODS

A prostate cancer cell line PC3 was used to establish xenograft model in NOD/SCID mice. After tumor growth, the mice were injected with ICG through the tail vein. Xenografts and surrounding tissues were imaged with NIR camera 24 hours after intravenous ICG, and tumor-to-background ratios were calculated. We then performed a pilot human study to evaluate the role of NIR imaging in robotic PLND after systemic ICG in 4 patients with prostate cancer and preoperative lymphadenopathy.

RESULTS

ICG localized to PC3 xenografts in the mice and all xenografts were highly fluorescent compared with surrounding tissues, with a median tumor-to-background ratio of 2.85 (interquartile range = 2.64-3.90). In the human study, intraoperative in vivo NIR imaging identified 3 of the 4 preoperative lymphadenopathies as fluorescence-positive, and back table ex vivo NIR imaging identified all 4 lymphadenopathies as fluorescence-positive. All the lymphadenopathies were found to be LNMs by pathologic examination. Two of the four cases had additional LNMs, all of which were fluorescence-positive with intraoperative in vivo NIR imaging.

CONCLUSION

Intravenously administered ICG accumulates in prostate cancers in both a murine model and human patients. NIR fluorescence based on intravenous ICG may serve as a useful tool to facilitate the identification of positive nodes during PLND in patients with higher risk of LNMs.

The second window ICG technique demonstrates a broad plateau period for near infrared fluorescence tumor contrast in glioblastoma

INTRODUCTION

Fluorescence-guided surgery has emerged as a powerful tool to detect, localize and resect tumors in the operative setting. Our laboratory has pioneered a novel way to administer an FDA-approved near-infrared (NIR) contrast agent to help surgeons with this task. This technique, coined Second Window ICG, exploits the natural permeability of tumor vasculature and its poor clearance to deliver high doses of indocyanine green (ICG) to tumors. This technique differs substantially from established ICG video angiography techniques that visualize ICG within minutes of injection. We hypothesized that Second Window ICG can provide NIR optical contrast with good signal characteristics in intracranial brain tumors over a longer period of time than previously appreciated with ICG video angiography alone. We tested this hypothesis in an intracranial mouse glioblastoma model, and corroborated this in a human clinical trial.

METHODS

Intracranial tumors were established in 20 mice using the U251-Luc-GFP cell line. Successful grafts were confirmed with bioluminescence. Intravenous tail vein injections of 5.0 mg/kg (high dose) or 2.5 mg/kg (low dose) ICG were performed. The Perkin Elmer IVIS Spectrum (closed field) was used to visualize NIR fluorescence signal at seven delayed time points following ICG injection. NIR signals were quantified using LivingImage software. Based on the success of our results, human subjects were recruited to a clinical trial and intravenously injected with high dose 5.0 mg/kg. Imaging was performed with the VisionSense Iridium (open field) during surgery one day after ICG injection.

RESULTS

In the murine model, the NIR signal-to-background ratio (SBR) in gliomas peaks at one hour after infusion, then plateaus and remains strong and stable for at least 48 hours. Higher dose 5.0 mg/kg improves NIR signal as compared to lower dose at 2.5 mg/kg (SBR = 3.5 vs. 2.8; P = 0.0624). Although early (≤ 6 hrs) visualization of the Second Window ICG accumulation in gliomas is stronger than late (≥24 hrs) visualization (SBR = 3.94 vs. 2.32; p<0.05) there appears to be a long plateau period of stable ICG NIR signal accumulation within tumors in the murine model. We call this long plateau period the "Second Window" of ICG. In glioblastoma patients, the delayed visualization of intratumoral NIR signal was strong (SBR 7.50 ± 0.74), without any significant difference within the 19 to 30 hour visualization window (R2 = 0.019).

CONCLUSION

The Second Window ICG technique allows neurosurgeons to deliver NIR optical contrast agent to human glioblastoma patients, thus providing real-time tumor identification in the operating room. This nonspecific tumor accumulation of ICG within the tumor provides strong signal to background contrast, and is not significantly time dependent between 6 hours to 48 hours, providing a broad plateau for stable visualization. This finding suggests that optimal imaging of the "Second Window of ICG" may be within this plateau period, thus providing signal uniformity across subjects.

Intraoperative near-infrared imaging of mesothelioma

Though difficult to achieve, complete resection of malignant pleural mesothelioma is paramount to improving patient survival. Surgeons have traditionally been limited to using visual inspection and manual palpation to locate and remove cancerous tissue. However, intraoperative molecular imaging (IMI) is a promising new technology in surgery. Molecular imaging utilizes a fluorescent tracer that selectively accumulates in cancer cells. An imaging device is then used to detect and augment the fluorescent signal emitted from the fluorescent cancer cells. Our group and others have demonstrated that molecular imaging with either indocyanine green (ICG) or a folate receptor alpha (FRα) targeted fluorophore can accurately identify a number of intrathoracic malignancies. Early studies of intraoperative imaging have suggested its efficacy for malignant pleural mesothelioma. In a murine model of mesothelioma, intraoperative imaging was found to have sensitivity of 87% and specificity of 83%. In a pilot human study, eight patients with biopsy-proven epithelial malignant pleural mesothelioma were administered 5 mg/kg of intravenous ICG injection 24 h prior to resection. The following day, a near-infrared (NIR) imaging device was used to detect tumor fluorescence intraoperatively. After what was believed to be complete tumor excision, the wound bed was re-imaged for residual fluorescence indicative of retained tumor. When residual fluorescence was detected, additional tissue was resected, if feasible, and specimens were sent for pathologic correlation. In all cases, intraoperative fluorescence localized to mesothelioma deposits which were confirmed on final pathology. Following resection, fluorescence was confirmed ex vivo with a mean tumor-to-background ratio (TBR) of 3.2 (IQR: 2.9-3.4). It is hoped that this technology will improve outcomes for mesothelioma patients by allowing for a more complete oncologic resection.