ICG-Fluorescence Imaging for Margin Assessment During Minimally Invasive Colorectal Liver Metastasis Resection.

Importance: Unintended tumor-positive resection margins occur frequently during minimally invasive surgery for colorectal liver metastases and potentially negatively influence oncologic outcomes. Objective: To assess whether indocyanine green (ICG)-fluorescence-guided surgery is associated with achieving a higher radical resection rate in minimally invasive colorectal liver metastasis surgery and to assess the accuracy of ICG fluorescence for predicting the resection margin status. Design, Setting, and Participants: The MIMIC (Minimally Invasive, Indocyanine-Guided Metastasectomy in Patients With Colorectal Liver Metastases) trial was designed as a prospective single-arm multicenter cohort study in 8 Dutch liver surgery centers. Patients were scheduled to undergo minimally invasive (laparoscopic or robot-assisted) resections of colorectal liver metastases between September 1, 2018, and June 30, 2021. Exposures: All patients received a single intravenous bolus of 10 mg of ICG 24 hours prior to surgery. During surgery, ICG-fluorescence imaging was used as an adjunct to ultrasonography and regular laparoscopy to guide and assess the resection margin in real time. The ICG-fluorescence imaging was performed during and after liver parenchymal transection to enable real-time assessment of the tumor margin. Absence of ICG fluorescence was favorable both during transection and in the tumor bed directly after resection. Main Outcomes and Measures: The primary outcome measure was the radical (R0) resection rate, defined by the percentage of colorectal liver metastases resected with at least a 1 mm distance between the tumor and resection plane. Secondary outcomes were the accuracy of ICG fluorescence in detecting margin-positive (R1; <1 mm margin) resections and the change in surgical management. Results: In total, 225 patients were enrolled, of whom 201 (116 [57.7%] male; median age, 65 [IQR, 57-72] years) with 316 histologically proven colorectal liver metastases were included in the final analysis. The overall R0 resection rate was 92.4%. Re-resection of ICG-fluorescent tissue in the resection cavity was associated with a 5.0% increase in the R0 percentage (from 87.4% to 92.4%; P < .001). The sensitivity and specificity for real-time resection margin assessment were 60% and 90%, respectively (area under the receiver operating characteristic curve, 0.751; 95% CI, 0.668-0.833), with a positive predictive value of 54% and a negative predictive value of 92%. After training and proctoring of the first procedures, participating centers that were new to the technique had a comparable false-positive rate for predicting R1 resections during the first 10 procedures (odds ratio, 1.36; 95% CI, 0.44-4.24). The ICG-fluorescence imaging was associated with changes in intraoperative surgical management in 56 (27.9%) of the patients. Conclusions and Relevance: In this multicenter prospective cohort study, ICG-fluorescence imaging was associated with an increased rate of tumor margin-negative resection and changes in surgical management in more than one-quarter of the patients. The absence of ICG fluorescence during liver parenchymal transection predicted an R0 resection with 92% accuracy. These results suggest that use of ICG fluorescence may provide real-time feedback of the tumor margin and a higher rate of complete oncologic resection.

Intraoperative Fluorescence Imaging During Robotic Pancreatoduodenectomy to Detect Suture-Induced Hypoperfusion of the Pancreatic Stump as a Predictor of Postoperative Pancreatic Fistula (FLUOPAN): Prospective Proof-of-concept Study.

Background: A potential downside of robotic pancreatoduodenectomy (RPD) is the lack of tactile feedback when tying sutures, which could be especially perilous during pancreatic anastomosis. Near-infrared fluorescence imaging with indocyanine green (NIRF-ICG) could detect transpancreatic-suture-induced hypoperfusion of the pancreatic stump during RPD, which may be related to postoperative pancreatic fistula (POPF) grade B/C, but studies are lacking. Methods: This prospective study included 37 patients undergoing RPD to assess the relation between pancreatic stump hypoperfusion as objectified with NIRF-ICG using Firefly and the rate of POPF grade B/C. In 27 patients, NIRF-ICG was performed after tying down the transpancreatic U-sutures. In 10 'negative control' patients, NIRF-ICG was performed before tying these sutures. Results: Pancreatic stump hypoperfusion was detected using NIRF-ICG in 9/27 patients (33%) during RPD. Hypoperfusion was associated with POPF grade B/C (67% [6/9 patients] versus 17% [3/18 patients], P = 0.026). No hypoperfusion was objectified in 10 'negative controls'. Conclusions: Transpancreatic-suture-induced pancreatic stump hypoperfusion can be detected using NIRF-ICG during RPD and was associated with POPF grade B/C. Surgeons could use NIRF-ICG to adapt their suturing approach during robotic pancreatico-jejunostomy. Further larger prospective studies are needed to validate the association between transpancreatic-suture-induced hypoperfusion and POPF.

Nanobody-targeted photodynamic therapy induces significant tumor regression of trastuzumab-resistant HER2-positive breast cancer, after a single treatment session.

RATIONALE: A substantial number of breast cancer patients with an overexpression of the human epidermal growth factor receptor 2 (HER2) have residual disease after neoadjuvant therapy or become resistant to trastuzumab. Photodynamic therapy (PDT) using nanobodies targeted to HER2 is a promising treatment option for these patients. Here we investigate the in vitro and in vivo antitumor efficacy of HER2-targeted nanobody-photosensitizer (PS) conjugate PDT. METHODS: Nanobodies targeting HER2 were obtained from phage display selections. Monovalent nanobodies were engineered into a biparatopic construct. The specificity of selected nanobodies was tested in immunofluorescence assays and their affinity was evaluated in binding studies, both performed in a panel of breast cancer cells varying in HER2 expression levels. The selected HER2-targeted nanobodies 1D5 and 1D5-18A12 were conjugated to the photosensitizer IRDye700DX and tested in in vitro PDT assays. Mice bearing orthotopic HCC1954 trastuzumab-resistant tumors with high HER2 expression or MCF-7 tumors with low HER2 expression were intravenously injected with nanobody-PS conjugates. Quantitative fluorescence spectroscopy was performed for the determination of the local pharmacokinetics of the fluorescence conjugates. After nanobody-PS administration, tumors were illuminated to a fluence of 100 J∙cm-2, with a fluence rate of 50 mW∙cm-2, and thereafter tumor growth was measured with a follow-up until 30 days. RESULTS: The selected nanobodies remained functional after conjugation to the PS, binding specifically and with high affinity to HER2-positive cells. Both nanobody-PS conjugates potently and selectively induced cell death of HER2 overexpressing cells, either sensitive or resistant to trastuzumab, with low nanomolar LD50 values. In vivo, quantitative fluorescence spectroscopy showed specific accumulation of nanobody-PS conjugates in HCC1954 tumors and indicated 2 h post injection as the most suitable time point to apply light. Nanobody-targeted PDT with 1D5-PS and 1D5-18A12-PS induced significant tumor regression of trastuzumab-resistant high HER2 expressing tumors, whereas in low HER2 expressing tumors only a slight growth delay was observed. CONCLUSION: Nanobody-PS conjugates accumulated selectively in vivo and their fluorescence could be detected through optical imaging. Upon illumination, they selectively induced significant tumor regression of HER2 overexpressing tumors with a single treatment session. Nanobody-targeted PDT is therefore suggested as a new additional treatment for HER2-positive breast cancer, particularly of interest for trastuzumab-resistant HER2-positive breast cancer. Further studies are now needed to assess the value of this approach in clinical practice.

Fluorescent imaging using indocyanine green during esophagectomy to prevent surgical morbidity: a systematic review and meta-analysis.

BACKGROUND: Fluorescent imaging using indocyanine green (ICG) is an emerging technique that aids the surgeon with intraoperative decision making during upper gastrointestinal cancer surgery. In this systematic review we aim to provide an overview of current practice of fluorescence imaging using ICG during esophagectomy, and to show how this technology can prevent surgical morbidity, such as anastomotic leakage, graft necrosis and chylothorax. METHODS: The PRISMA standard for systematic reviews was used. The PubMed and Embase database were searched to identify articles matching our systematic literature search. Two authors screened all included articles for eligibility. Risk of bias was assessed for all included articles. RESULTS: A total of 25 articles were included in this review: 22 articles on perfusion assessment, and three on the detection of chyle fistula. Five out of 22 articles concerning perfusion assessment evaluated fluorescence signals in quantitative values. In 20 articles the pooled incidence of anastomotic leakage and graft necrosis in the ICG group was 11.10% (95% CI: 8.06-15.09%) and in eight studies the pooled change in management rate was 24.55% (95% CI: 19.16-30.88%). After change in management, the pooled incidence of anastomotic leakage and graft necrosis was 14.08% (95% CI: 6.55-27.70%). A meta-analysis showed that less anastomotic leakages and graft necrosis occur in the ICG group (OR 0.30, 95% CI: 0.14-0.63). Three case-reports (N=3) were identified regarding chyle fistula detection, and ICG lymphography detected the thoracic duct in all cases and the chyle fistula in one case. CONCLUSIONS: Fluorescence imaging using ICG is a promising and safe technology to reduce surgical morbidity after esophagectomy with continuity restoration. ICG fluorescence angiography showed a reduction in anastomotic leakage and graft necrosis. Future studies are needed to demonstrate the feasibility of ICG lymphography for chyle fistula detection.

Detecting tumour-positive resection margins after oral cancer surgery by spraying a fluorescent tracer activated by gamma-glutamyltranspeptidase.

OBJECTIVES: Tumour-positive resection margins are a major problem during oral cancer surgery. gGlu-HMRG is a tracer that becomes fluorescent upon activation by gamma-glutamyltranspeptidase (GGT). This study aims to investigate the combination of gGlu-HMRG and a clinical fluorescence imaging system for the detection of tumour-positive resection margins. MATERIALS AND METHODS: The preclinical Maestro and clinical Artemis imaging systems were compared in vitro and ex vivo with cultured human head and neck cancer cells (OSC19, GGT-positive; and FaDu, GGT negative) and tumour-bearing nude mice. Subsequently, frozen sections of normal and oral cancer tissues were ex vivo sprayed with gGlu-HMRG to determine the sensitivity and specificity. Finally, resection margins of patients with suspected oral cancer were ex vivo sprayed with gGlu-HMRG to detect tumour-positive resection margins. RESULTS: Both systems could be used to detect gGlu-HMRG activation in vitro and ex vivo in GGT positive cancer cells. Sensitivity and specificity of gGlu-HMRG and the Artemis on frozen tissue samples was 80% and 87%, respectively. Seven patients undergoing surgery for suspected oral cancer were included. In three patients fluorescence was observed at the resection margin. Those margins were either tumour-positive or within 1 mm of tumour. The margins of the other patients were clear (≥8 mm). CONCLUSION: This study demonstrates the feasibility to detect tumour-positive resection margins with gGlu-HMRG and a clinical fluorescence imaging system. Applying this technique would enable intraoperative screening of the entire resection margin and allow direct re-resection in case of tumour-positivity.

EGFR targeted nanobody-photosensitizer conjugates for photodynamic therapy in a pre-clinical model of head and neck cancer.

Photodynamic therapy (PDT) induces cell death through local light activation of a photosensitizer (PS) and has been used to treat head and neck cancers. Yet, common PS lack tumor specificity, which leads to collateral damage to normal tissues. Targeted delivery of PS via antibodies has pre-clinically improved tumor selectivity. However, antibodies have long half-lives and relatively poor tissue penetration, which could limit therapeutic efficacy and lead to long photosensitivity. Here, in this feasibility study, we evaluate at the pre-clinical level a recently introduced format of targeted PDT, which employs nanobodies as targeting agents and a water-soluble PS (IRDye700DX) that is traceable through optical imaging. In vitro, the PS solely binds to cells and induces phototoxicity on cells overexpressing the epidermal growth factor receptor (EGFR), when conjugated to the EGFR targeted nanobodies. To investigate whether this new format of targeted PDT is capable of inducing selective tumor cell death in vivo, PDT was applied on an orthotopic mouse tumor model with illumination at 1h post-injection of the nanobody-PS conjugates, as selected from quantitative fluorescence spectroscopy measurements. In parallel, and as a reference, PDT was applied with an antibody-PS conjugate, with illumination performed 24h post-injection. Importantly, EGFR targeted nanobody-PS conjugates led to extensive tumor necrosis (approx. 90%) and almost no toxicity in healthy tissues, as observed through histology 24h after PDT. Overall, results show that these EGFR targeted nanobody-PS conjugates are selective and able to induce tumor cell death in vivo. Additional studies are now needed to assess the full potential of this approach to improving PDT.