M. Hekman

Targeted Dual-Modality Imaging in Renal Cell Carcinoma: An Ex Vivo Kidney Perfusion Study

Purpose: Antibodies labeled with both a near-infrared fluorescent dye and a radionuclide can be used for tumor-targeted intraoperative dual-modality imaging. Girentuximab is a chimeric monoclonal antibody against carbonic anhydrase IX (CAIX), an antigen expressed in 95% of clear cell renal cell carcinoma (ccRCC). This study aimed to assess the feasibility of targeted dual-modality imaging with 111In-girentuximab-IRDye800CW using ex vivo perfusion of human tumorous kidneys. Experimental Design: Seven radical nephrectomy specimens from patients with ccRCC were perfused during 11 to 15 hours with dual-labeled girentuximab and subsequently rinsed during 2.5 to 4 hours with Ringers Lactate solution. Then, dual-modality imaging was performed on a 5- to 10-mm-thick lamella of the kidney. Fluorescence imaging was performed with a clinical fluorescence camera set-up as applied during image-guided surgery. The distribution of Indium-111 in the slice of tumor tissue was visualized by autoradiography. In two perfusions, an additional dual-labeled control antibody was added to demonstrate specific accumulation of dual-labeled girentuximab in CAIX-expressing tumor tissue. Results: Both radionuclide and fluorescence imaging clearly visualized uptake in tumor tissue and tumor-to-normal tissue borders, as confirmed (immuno)histochemically and by gamma counting. Maximum uptake of girentuximab in tumor tissue was 0.33% of the injected dose per gram (mean, 0.12 %ID/g; range, 0.01–0.33 %ID/g), whereas maximum uptake in the normal kidney tissue was 0.04 %ID/g (mean, 0.02 %ID/g; range, 0.00–0.04 %ID/g). Conclusions: Dual-labeled girentuximab accumulated specifically in ccRCC tissue, indicating the feasibility of dual-modality imaging to detect ccRCC. A clinical study to evaluate intraoperative dual-modality imaging in patients with ccRCC has been initiated. Clin Cancer Res; 22(18); 4634–42. ©2016 AACR.

Detection of Micrometastases Using SPECT/Fluorescence Dual-Modality Imaging in a CEA-Expressing Tumor Model

Intraoperative dual-modality imaging can help the surgeon distinguish tumor from normal tissue. This technique may prove particularly valuable if small tumors need to be removed that are difficult to detect with the naked eye. The humanized anticarcinoembryonic antigen (anti-CEA) monoclonal antibody, labetuzumab, can be used as a tumor-targeting agent in colorectal cancer, since CEA is overexpressed in approximately 95% of colorectal cancer. Dual-labeled labetuzumab, labeled with both a near-infrared fluorescent dye (IRDye800CW) and a radioactive label (111In), can be used as a tracer for dual-modality imaging. This study aimed to assess whether dual-modality imaging using 111In-diethylenetriaminepentaacetic acid (DTPA)–labetuzumab-IRDye800CW can detect pulmonary micrometastases in a mouse model. Methods: Pulmonary GW-39 human colonic carcinoma microcolonies were induced in athymic BALB/c mice by intravenous injection of 100 μL of a GW-39 cell suspension. After 1, 2, 3, and 4 wk of tumor growth, dual-modality imaging was performed 3 d after intravenous injection of 111In-DTPA-labetuzumab-IRDye800CW (10 μg, 25 MBq). Small-animal SPECT images and optical images were acquired, and image-guided surgery was performed. Finally, the biodistribution of the dual-labeled tracer was determined. Formalin-fixed sections of the lungs were analyzed using fluorescence imaging, autoradiography, and immunohistochemistry. Results: Submillimeter pulmonary tumor colonies could be visualized with both small-animal SPECT and fluorescence imaging from the first week of tumor growth, before they became visible to the naked eye. Furthermore, dual-modality imaging could be used to guide resection of tumors. Mean uptake (percentage injected dose per gram) of the dual-labeled tracer in tumors was 17.2 ± 5.4 and 16.5 ± 4.4 at weeks 3 and 4, respectively. Immunohistochemical analysis of the tumorous lungs showed that the distribution of the radioactive and fluorescent signal colocalized with CEA-expressing tumors. Conclusion: Dual-modality imaging after injection of 111In-labetuzumab-IRDye800CW can be used to detect submillimeter CEA-expressing pulmonary tumors before they become visible to the naked eye, supporting the added value of this technique in the resection of small tumors.

Intraoperative Imaging Techniques to Support Complete Tumor Resection in Partial Nephrectomy

CONTEXT With more complex kidney tumors treated by nephron-sparing surgery (NSS), complete tumor resection is becoming increasingly challenging. Intraoperative imaging may improve the establishment of negative surgical margins. OBJECTIVE To discuss intraoperative imaging techniques that may help achieve complete tumor resection in NSS of renal tumors. EVIDENCE ACQUISITION PubMed was searched for English articles on intraoperative imaging during NSS of renal cell carcinoma published after 2005, and a reference search of retrieved articles was performed. EVIDENCE SYNTHESIS Included studies reported about ultrasonography, fluorescence imaging, augmented reality, optical coherence tomography, and ex vivo magnetic resonance imaging (MRI). The number of patients included in these studies is limited, and randomized controlled trials have not been performed. Ultrasonography is a well-established technique to assess tumor localization and may be used to evaluate surgical margins of the resected specimen. Fluorescence imaging with indocyanine green may help differentiate tumor from normal kidney tissue. It is yet unclear whether fluorescence imaging can detect positive surgical margins. Augmented reality is best studied in robotic laparoscopic surgery, and may be useful for tumor localization and resection, if the problem of tissue deformation during surgery can be solved. More results have to be awaited about optical coherence tomography and ex vivo MRI. CONCLUSIONS Ultrasonography is a widely used technique to assist the surgeon in partial nephrectomy nowadays, while the use of fluorescence imaging and augmented reality is emerging. Although various techniques can be used during NSS, the added value of intraoperative imaging to support negative surgical margins remains to be demonstrated. PATIENT SUMMARY In this review, we discuss the value of various intraoperative imaging techniques that may help a urologist achieve complete tumor resection in nephron-sparing surgery for kidney tumors. Ultrasonography, fluorescence imaging, and augmented reality have been studied best, but their added value needs further investigation.

Improved Intraoperative Detection of Ovarian Cancer by Folate Receptor Alpha Targeted Dual-Modality Imaging

Complete resection of tumor lesions in advanced stage ovarian cancer patients is of utmost importance, since the extent of residual disease after surgery strongly affects survival. Intraoperative imaging may be useful to improve surgery in these patients. Farletuzumab is a humanized IgG1 antibody that specifically recognizes the folate receptor alpha (FRα). Labeled with a radiolabel and a fluorescent dye, farletuzumab may be used for the intraoperative detection of ovarian cancer lesions. The current aim is to demonstrate the feasibility of FRα-targeted dual-modality imaging using 111In-farletuzumab-IRDye800CW in an intraperitoneal ovarian cancer model. Biodistribution studies were performed 3 days after injection of 3, 10, 30, or 100 μg of 111In-farletuzumab-IRDye800CW in mice with subcutaneous IGROV-1 tumors (5 mice per group). In mice with intraperitoneal IGROV-1 tumors the nonspecific uptake of 111In-farletuzumab-IRDye800CW was determined by coinjecting an excess of unlabeled farletuzumab. MicroSPECT/CT and fluorescence imaging were performed 3 days after injection of 10 μg of 111In-farletuzumab-IRDye800CW. FRα expression in tumors was determined immunohistochemically. Optimal tumor-to-blood-ratios (3.4–3.7) were obtained at protein doses up to 30 μg. Multiple intra-abdominal tumor lesions were clearly visualized by microSPECT/CT, while uptake in normal tissues was limited. Fluorescence imaging was used to visualize and guide resection of superficial tumors. Coinjection of an excess of unlabeled farletuzumab significantly decreased tumor uptake of 111In-farletuzumab-IRDye800CW (69.4 ± 27.6 versus 18.3 ± 2.2% ID/g, p < 0.05). Immunohistochemical analyses demonstrated that the radioactive and fluorescent signal corresponded with FRα-expressing tumor lesions. FRα-targeted SPECT/fluorescence imaging using 111In-farletuzumab-IRDye800CW can be used to detect ovarian cancer in vivo and could be a valuable tool for enhanced intraoperative tumor visualization in patients with intraperitoneal metastases of ovarian cancer.

Tumor-targeted Dual-modality Imaging to Improve Intraoperative Visualization of Clear Cell Renal Cell Carcinoma: A First in Man Study

Intraoperative imaging with antibodies labeled with both a radionuclide for initial guidance and a near-infrared dye for adequate tumor delineation may overcome the main limitation of fluorescence imaging: the limited penetration depth of light in biological tissue. In this study, we demonstrate the feasibility and safety of intraoperative dual-modality imaging with the carbonic anhydrase IX (CAIX)-targeting antibody 111In-DOTA-girentuximab-IRDye800CW in clear cell renal cell carcinoma (ccRCC) patients. Methods: A phase I protein dose escalation study was performed in patients with a primary renal mass who were scheduled for surgery. 111In-DOTA-girentuximab-IRDye800CW (5, 10, 30, or 50 mg, n=3 ccRCC patients per dose level) was administered intravenously and after 4 days SPECT/CT imaging was performed. Seven days after antibody injection, surgery was performed with the use of a gamma probe and near-infrared fluorescence camera. Results: In total, fifteen patients were included (12 ccRCC, 3 CAIX-negative tumors). No study-related serious adverse events were observed. All ccRCC were visualized by SPECT/CT and localized by intraoperative gamma probe detection (mean tumor-to-normal kidney (T:N) ratio 2.5 ± 0.8), while the T:N ratio was 1.0 ± 0.1 in CAIX-negative tumors. ccRCC were hyperfluorescent at all protein doses and fluorescence imaging could be used for intraoperative tumor delineation, assessment of the surgical cavity and detection of (positive) surgical margins. The radiosignal was crucial for tumor localization in case of overlying fat tissue. Conclusion: This first in man study shows that tumor-targeted dual-modality imaging using 111In-DOTA-girentuximab-IRDye800CW is safe and can be used for intraoperative guidance of ccRCC resection.

Positron Emission Tomography/Computed Tomography with 89Zr-girentuximab Can Aid in Diagnostic Dilemmas of Clear Cell Renal Cell Carcinoma Suspicion

Based on the high expression of carbonic anhydrase IX (CAIX) in 95% of clear cell renal cell carcinoma (ccRCC), the anti-CAIX monoclonal antibody girentuximab can be used for the detection of ccRCC. This clinical study explores the value of 89Zr-labeled girentuximab positron emission tomography/computed tomography (PET/CT) imaging in diagnostic challenges regarding ccRCC. PET/CT imaging was performed 4 or 5 d after injection of 89Zr-girentuximab in patients with a primary renal mass (n=16) or a history of ccRCC (n=14). Scans were used for decision making (surgery/active surveillance) in case of indistinct renal masses. All resected PET-positive primary lesions proved to be ccRCC, while no lesion progression was seen in PET-negative masses. In patients suspected of recurrent/metastatic ccRCC, PET/CT with 89Zr-girentuximab was useful to confirm or exclude ccRCC, evaluate the extent of the disease, and differentiate from other cancers. In this group, 89Zr-girentuximab PET/CT resulted in a major change in clinical management in five patients (36%), while in three patients (21%) repeat biopsies could be avoided. We conclude that 89Zr-girentuximab PET/CT is a valuable diagnostic tool that can guide clinical decision making in case of diagnostic dilemmas concerning ccRCC suspicion. PATIENT SUMMARY Positron emission tomography/computed tomography imaging with 89Zr-girentuximab can be a valuable diagnostic tool to identify clear cell renal cell carcinoma.

1 Dual-modality imaging bij niercelcarcinoom. Een ex-vivonierperfusiestudie

SamenvattingBeeldgestuurde chirurgie kan van meerwaarde zijn om complete tumorresectie te bereiken. Hiervoor kunnen radioactieve en/of fluorescerende antitumorantilichamen gebruikt worden.