An LED light source and novel fluorophore combinations improve fluorescence laparoscopic detection of metastatic pancreatic cancer in orthotopic mouse models

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

A major barrier to the diagnosis and effective treatment of solid-tumor cancers is the difficulty in detection and visualization of tumor margins in primary and metastatic disease. The use of fluorescence can augment the surgeon's ability to detect cancer and aid in its resection. Several cancer types express carcinoembryonic antigen (CEA) including colorectal, pancreatic and gastric cancer. Antibodies to CEA have been developed and tagged with near-infrared fluorescent dyes. This review article surveyed the use of CEA antibodies conjugated to fluorescent probes for in vivo studies since 1990. PubMed and Google Scholar databases were queried, and 900 titles and abstracts were screened. Fifty-nine entries were identified as possibly meeting inclusion/exclusion criteria and were reviewed in full. Forty articles were included in the review and their citations were screened for additional entries. A total of 44 articles were included in the final review. The use of fluorescent anti-CEA antibodies has been shown to improve detection and resection of tumors in both murine models and clinically. The cumulative results indicate that fluorescent-conjugated anti-CEA antibodies have important potential to improve cancer diagnosis and surgery. In an emerging technology, anti-CEA fluorescent antibodies have also been successfully used for photoimmunotherapy treatment for cancer.

A review of tumor-specific fluorescence-guided surgery for colorectal cancer

The present study reviews the use of tumor-specific antibodies conjugated to fluorescent dyes in preclinical and clinical studies to enhance visualization of primary tumors and metastases for fluorescence-guided surgery (FGS) in colorectal cancer (CRC). A search strategy was developed using the peer-reviewed National Center for Biotechnology Information (NCBI) database on PubMed. Studies using tumor-specific fluorescence imaging and FGS techniques on murine models of colorectal cell lines or patient-derived orthotopic xenograft (PDOX) colorectal cancer are reviewed. A total of 24 articles were identified that met the inclusion criteria, 21 preclinical and 3 clinical trials. The most widely used target antigen in preclinical and clinical trials was carcinoembryonic antigen (CEA). Mouse studies and clinical studies have demonstrated that the use of FGS in CRC can aid in decreased residual tumor and decreased rates of recurrence. As the mainstay of colorectal cancer treatment is surgery, the addition of intraoperative fluorescence imaging can help locate tumor margins, visualize occult micro-metastases, drive surgical decision making and improve patient outcomes.

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

INTRODUCTION

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

ImmunoPET and Near-Infrared Fluorescence Imaging of Pancreatic Cancer with a Dual-Labeled Bispecific Antibody Fragment

Dual-targeted imaging agents have shown improved targeting efficiencies in comparison to single-targeted entities. The purpose of this study was to quantitatively assess the tumor accumulation of a dual-labeled heterobifunctional imaging agent, targeting two overexpressed biomarkers in pancreatic cancer, using positron emission tomography (PET) and near-infrared fluorescence (NIRF) imaging modalities. A bispecific immunoconjugate (heterodimer) of CD105 and tissue factor (TF) Fab' antibody fragments was developed using click chemistry. The heterodimer was dual-labeled with a radionuclide (⁶⁴Cu) and fluorescent dye. PET/NIRF imaging and biodistribution studies were performed in four-to-five week old nude athymic mice bearing BxPC-3 (CD105/TF^+/+) or PANC-1 (CD105/TF^-/-) tumor xenografts. A blocking study was conducted to investigate the specificity of the tracer. Ex vivo tissue staining was performed to compare TF/CD105 expression in tissues with PET tracer uptake to validate in vivo results. PET imaging of ⁶⁴Cu-NOTA-heterodimer-ZW800 in BxPC-3 tumor xenografts revealed enhanced tumor uptake (21.0 ± 3.4%ID/g; n = 4) compared to the homodimer of TRC-105 (9.6 ± 2.0%ID/g; n = 4; p < 0.01) and ALT-836 (7.6 ± 3.7%ID/g; n = 4; p < 0.01) at 24 h postinjection. Blocking studies revealed that tracer uptake in BxPC-3 tumors could be decreased by 4-fold with TF blocking and 2-fold with CD105 blocking. In the negative model (PANC-1), heterodimer uptake was significantly lower than that found in the BxPC-3 model (3.5 ± 1.1%ID/g; n = 4; p < 0.01). The specificity was confirmed by the successful blocking of CD105 or TF, which demonstrated that the dual targeting with ⁶⁴Cu-NOTA-heterodimer-ZW800 provided an improvement in overall tumor accumulation. Also, fluorescence imaging validated the PET imaging, allowing for clear delineation of the xenograft tumors. Dual-labeled heterodimeric imaging agents, like ⁶⁴Cu-NOTA-heterodimer-ZW800, may increase the overall tumor accumulation in comparison to single-targeted homodimers, leading to improved imaging of cancer and other related diseases.

Targeting the insulin growth factor-1 receptor with fluorescent antibodies enables high resolution imaging of human pancreatic cancer in orthotopic mouse models

The goal of the present study was to determine whether insulin-like growth factor-1 receptor (IGF-1R) antibodies, conjugated with bright fluorophores, could enable visualization of pancreatic cancer in orthotopic nude mouse models. IGF-1R antibody (clone 24-31) was conjugated with 550 nm or 650 nm fluorophores. Western blotting confirmed the expression of IGF-1R in Panc-1, BxPC3, and MIAPaCa-2 human pancreatic cancer cell lines. Labeling with fluorophore-conjugated IGF-1R antibody demonstrated fluorescent foci on the membrane of the pancreatic cancer cells. Subcutaneous Panc-1, BxPC-3, and MIA PaCa-2 tumors became fluorescent after intravenous administration of fluorescent IGF-1R antibodies. Orthotopically-transplanted BxPC-3 tumors became fluorescent with the conjugated IGF-1R antibodies, and were easily visible with intravital imaging. Gross and microscopic ex vivo imaging of resected pancreatic tumor and normal pancreas confirmed that fluorescence indeed came from the membrane of cancer cells, and it was stronger from the tumor than the normal tissue. The present study demonstrates that fluorophore-conjugated IGF-1R antibodies can visualize pancreatic cancer and it can be used with various imaging devices such as endoscopy and laparoscopy for diagnosis and fluorescence-guided surgery.

A dual-emitting core–shell carbon dot–silica–phosphor composite for LED plant grow light

Light-emitting diodes (LEDs) are widely used for artificial lighting in plant factories and have been applied for disease prevention and for accelerating plant growth.

Fluorescence-guided surgery of human prostate cancer experimental bone metastasis in nude mice using anti-CEA DyLight 650 for tumor illumination

The present report demonstrates efficacy of fluorescence-guided surgery (FGS) to resect and prevent recurrence of experimental skeletal metastasis in a nude-mouse model of human prostate cancer. Green fluorescent protein (GFP)-expressing PC-3 human prostate cancer cells were injected into the intramedullary cavity of the tibia in 25 nude mice. One week after implantation, monoclonal antibodies, specific for carcinoembryonic antigen (CEA), labeled with DyLight 650, were injected into the tail vein of 13 mice. Thirteen mice underwent FGS and 12 mice underwent bright-light surgery (BLS). Weekly GFP fluorescence imaging of the mice was performed to observe tumor recurrence. The extent of residual tumor after BLS was 13-fold greater than after FGS (p < 0.001). Time-course imaging visualized rapid growth of the residual tumor in the BLS group, whereas the FGS group showed only slight tumor growth and significantly improved disease-free survival of the treated mice. Our study demonstrated that FGS significantly reduced residual tumor as well as the recurrence of experimental prostate-cancer bone metastasis. The present results suggest that FGS will be effective for resection of skeletal metastases in selected patients with prostate cancer.

Fluorescent-Antibody Targeting of Insulin-Like Growth Factor-1 Receptor Visualizes Metastatic Human Colon Cancer in Orthotopic Mouse Models

Fluorescent-antibody targeting of metastatic cancer has been demonstrated by our laboratory to enable tumor visualization and effective fluorescence-guided surgery. The goal of the present study was to determine whether insulin-like growth factor-1 receptor (IGF-1R) antibodies, conjugated with bright fluorophores, could enable visualization of metastatic colon cancer in orthotopic nude mouse models. IGF-1R antibody (clone 24–31) was conjugated with 550 nm, 650 nm or PEGylated 650 nm fluorophores. Subcutaneous, orthotopic, and liver metastasis models of colon cancer in nude mice were targeted with the fluorescent IGF-1R antibodies. Western blotting confirmed the expression of IGF-1R in HT-29 and HCT 116 human colon cancer cell lines, both expressing green fluorescent protein (GFP). Labeling with fluorophore-conjugated IGF-1R antibody demonstrated fluorescent foci on the membrane of colon cancer cells. Subcutaneously- and orthotopically-transplanted HT-29-GFP and HCT 116-GFP tumors brightly fluoresced at the longer wavelengths after intravenous administration of fluorescent IGF-1R antibodies. Orthotopically-transplanted HCT 116-GFP tumors were brightly labeled by fluorescent IGF-1R antibodies such that they could be imaged non-invasively at the longer wavelengths. In an experimental liver metastasis model, IGF-1R antibodies conjugated with PEGylated 650 nm fluorophores selectively highlighted the liver metastases, which could then be non-invasively imaged. The IGF-1R fluorescent-antibody labeled liver metastases were very bright compared to the normal liver and the fluorescent-antibody label co-located with green fluorescent protein (GFP) expression of the colon cancer cells. The present study thus demonstrates that fluorophore-conjugated IGF-1R antibodies selectively visualize metastatic colon cancer and have clinical potential for improved diagnosis and fluorescence-guided surgery.

Molecular Imaging of Pancreatic Cancer with Antibodies

Development of novel imaging probes for cancer diagnostics remains critical for early detection of disease, yet most imaging agents are hindered by suboptimal tumor accumulation. To overcome these limitations, researchers have adapted antibodies for imaging purposes. As cancerous malignancies express atypical patterns of cell surface proteins in comparison to noncancerous tissues, novel antibody-based imaging agents can be constructed to target individual cancer cells or surrounding vasculature. Using molecular imaging techniques, these agents may be utilized for detection of malignancies and monitoring of therapeutic response. Currently, there are several imaging modalities commonly employed for molecular imaging. These imaging modalities include positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance (MR) imaging, optical imaging (fluorescence and bioluminescence), and photoacoustic (PA) imaging. While antibody-based imaging agents may be employed for a broad range of diseases, this review focuses on the molecular imaging of pancreatic cancer, as there are limited resources for imaging and treatment of pancreatic malignancies. Additionally, pancreatic cancer remains the most lethal cancer with an overall 5-year survival rate of approximately 7%, despite significant advances in the imaging and treatment of many other cancers. In this review, we discuss recent advances in molecular imaging of pancreatic cancer using antibody-based imaging agents. This task is accomplished by summarizing the current progress in each type of molecular imaging modality described above. Also, several considerations for designing and synthesizing novel antibody-based imaging agents are discussed. Lastly, the future directions of antibody-based imaging agents are discussed, emphasizing the potential applications for personalized medicine.

Current status and future perspectives of fluorescence-guided surgery for cancer

Curative cancer surgery is dependent on the removal of all primary tumor and metastatic cancer cells. Preoperative imaging, intraoperative inspection and palpation, as well as pathological margin confirmation aid the surgeon, but these methods are lacking in sensitivity and can be highly subjective. Techniques in fluorescence-guided surgery (FGS) are emerging that selectively illuminate cancer cells, enhancing the distinction between tumors and surrounding tissues with the potential for single-cell sensitivity. FGS enhances tumor detection, surgical navigation, margin confirmation, and in some cases can be combined with therapeutic techniques to eliminate microscopic disease. In this review, we describe the preclinical developments and currently-used techniques for FGS.

Tumor imaging technologies in mouse models

In this chapter, we describe protocols for tumor imaging technologies in mouse models. These models utilize human cancer cell lines which have been genetically engineered to selectively express high levels of green fluorescent protein (GFP) or red fluorescent protein (RFP). Tumors with fluorescent genetic reporters are established subcutaneously in nude mice, and fragments of the subcutaneous tumors are then surgically transplanted onto the orthotopic organ. Locoregional tumor growth and distant metastasis of these orthotopic implants occur spontaneously and rapidly throughout the abdomen in a manner consistent with clinical human disease. Highly specific, high-resolution, real-time quantitative fluorescence imaging of tumor growth and metastasis may be achieved in vivo without the need for contrast agents, invasive techniques, or expensive imaging equipment. Transplantation of RFP-expressing tumor fragments onto the pancreas of GFP- or cyan fluorescent protein (CFP)-expressing transgenic nude mice was used to facilitate visualization of tumor-host interaction between the pancreatic cancer cells and host-derived stroma and vasculature. Such in vivo models have enabled us to visualize in real time and acquire images of the progression of pancreatic cancer in the live animal, and to demonstrate the real-time antitumor and antimetastatic effects of several novel therapeutic strategies on a variety of malignancies. We discuss studies from our laboratory that demonstrate that fluorescence imaging in mice is complementary to other modalities such as magnetic resonance imaging (MRI) or ultrasound. These fluorescent models are powerful and reliable tools with which to investigate metastatic human cancer and novel therapeutic strategies directed against it.

Precise navigation surgery of tumours in the lung in mouse models enabled by in situ fluorescence labelling with a killer-reporter adenovirus

Background

Current methods of image-guided surgery of tumours of the lung mostly rely on CT. A sensitive procedure of selective tumour fluorescence labelling would allow simple and high-resolution visualisation of the tumour for precise surgical navigation.

Methods

Human lung cancer cell lines H460 and A549 were genetically transformed to express red fluorescent protein (RFP). Tumours were grown subcutaneously for each cell line and harvested and minced for surgical orthotopic implantation on the left lung of nude mice. Tumour growth was measured by fluorescence imaging. After the tumours reached 5 mm in diameter, they were injected under fluorescence guidance with the telomerase-dependent green fluorescent protein (GFP)-containing adenovirus, OBP-401. Viral labelling of the lung tumours with GFP precisely colocalised with tumour RFP expression. Three days after administration of OBP-401, fluorescence-guided surgery (FGS) was performed.

Results

FGS of tumours in the lung was enabled by labelling with a telomerase-dependent adenovirus containing the GFP gene. Tumours in the lung were selectively and brightly labelled. FGS enabled complete lung tumour resection with no residual fluorescent tumour.

Conclusions

FGS of tumours in the lung is feasible and more effective than bright-light surgery.

Color-coding cancer and stromal cells with genetic reporters in a patient-derived orthotopic xenograft (PDOX) model of pancreatic cancer enhances fluorescence-guided surgery

Precise fluorescence-guided surgery (FGS) for pancreatic cancer has the potential to greatly improve the outcome in this recalcitrant disease. To achieve this goal, we have used genetic reporters to color code cancer and stroma cells in a patient-derived orthotopic xenograft (PDOX) model. The telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 was used to label the cancer cells of a pancreatic cancer PDOX. The PDOX was previously grown in a red fluorescent protein (RFP) transgenic mouse that stably labeled the PDOX stroma cells bright red. The color-coded PDOX model enabled FGS to completely resect the pancreatic tumors including stroma. Dual-colored FGS significantly prevented local recurrence, which bright-light surgery or single-color FGS could not. FGS, with color-coded cancer and stroma cells has important potential for improving the outcome of recalcitrant-cancer surgery.

Experimental Curative Fluorescence-guided Surgery of Highly Invasive Glioblastoma Multiforme Selectively Labeled With a Killer-reporter Adenovirus

Fluorescence-guided surgery (FGS) of cancer is an area of intense current interest. However, although benefits have been demonstrated with FGS, curative strategies need to be developed. Glioblastoma multiforme (GBM) is one of the most invasive of cancers and is not totally resectable using standard bright-light surgery (BLS) or current FGS strategies. We report here a curative strategy for FGS of GBM. In this study, telomerase-dependent adenovirus OBP-401 infection brightly and selectively labeled GBM with green fluorescent protein (GFP) for FGS in orthotopic nude mouse models. OBP-401-based FGS enabled curative resection of GBM without recurrence for at least 150 days, compared to less than 30 days with BLS.

Near infra-red photoimmunotherapy with anti-CEA-IR700 results in extensive tumor lysis and a significant decrease in tumor burden in orthotopic mouse models of pancreatic cancer

Photoimmunotherapy (PIT) of cancer utilizes tumor-specific monoclonal antibodies conjugated to a photosensitizer phthalocyanine dye IR700 which becomes cytotoxic upon irradiation with near infrared light. In this study, we aimed to evaluate the efficacy of PIT on human pancreatic cancer cells in vitro and in vivo in an orthotopic nude mouse model. The binding capacity of anti-CEA antibody to BxPC-3 human pancreatic cancer cells was determined by FACS analysis. An in vitro cytotoxicity assay was used to determine cell death following treatment with PIT. For in vivo determination of PIT efficacy, nude mice were orthotopically implanted with BxPC-3 pancreatic tumors expressing green fluorescent protein (GFP). After tumor engraftment, the mice were divided into two groups: (1) treatment with anti-CEA-IR700 + 690 nm laser and (2) treatment with 690 nm laser only. Anti-CEA-IR700 (100 μg) was administered to group (1) via tail vein injection 24 hours prior to therapy. Tumors were then surgically exposed and treated with phototherapy at an intensity of 150 mW/cm² for 30 minutes. Whole body imaging was done subsequently for 5 weeks using an OV-100 small animal imaging system. Anti-CEA-IR700 antibody bound to the BxPC3 cells to a high degree as shown by FACS analysis. Anti-CEA-IR700 caused extensive cancer cell killing after light activation compared to control cells in cytotoxicity assays. In the orthotopic models of pancreatic cancer, the anti-CEA-IR700 group had significantly smaller tumors than the control after 5 weeks (p<0.001). There was no significant difference in the body weights of mice in the anti-CEA-IR700 and control groups indicating that PIT was well tolerated by the mice.

Fluorescence-guided surgery of retroperitoneal-implanted human fibrosarcoma in nude mice delays or eliminates tumor recurrence and increases survival compared to bright-light surgery

The aim of this study is to determine if fluorescence-guided surgery (FGS) can eradicate human fibrosarcoma growing in the retroperitoneum of nude mice. One week after retroperitoneal implantation of human HT1080 fibrosarcoma cells, expressing green fluorescent protein (GFP) (HT-1080-GFP), in nude mice, bright-light surgery (BLS) was performed on all tumor-bearing mice (n = 22). After BLS, mice were randomized into 2 treatment groups; BLS-only (n = 11) or the combination of BLS + FGS (n = 11). The residual tumors remaining after BLS were resected with FGS using a hand-held portable imaging system under fluorescence navigation. The average residual tumor area after BLS + FGS was significantly smaller than after BLS-only (0.4 ± 0.4 mm² and 10.5 ± 2.4 mm², respectively; p = 0.006). Five weeks after surgery, the fluorescent-tumor areas of BLS- and BLS + FGS-treated mice were 379 ± 147 mm² and 11.7 ± 6.9 mm², respectively, indicating that FGS greatly inhibited tumor recurrence compared to BLS. The combination of BLS + FGS significantly decreased fibrosarcoma recurrence compared to BLS-only treated mice (p < 0.001). Mice treated with BLS+FGS had a significantly higher disease-free survival rate than mice treated with BLS-only at five weeks after surgery. These results suggest that combination of BLS + FGS significantly reduced the residual fibrosarcoma volume after BLS and improved disease-free survival.

Photoimmunotherapy lowers recurrence after pancreatic cancer surgery in orthotopic nude mouse models

BACKGROUND

Photoimmunotherapy (PIT) is based on the use of a monoclonal antibody specific to cancer epitopes conjugated to a photosensitizer near-infrared phthalocyanine dye (IR700). In this study, PIT with IR700 conjugated to anti-carcinoembryonic antigen (CEA) was used as an adjunct to surgery in orthotopically-implanted human pancreatic cancer in a nude mouse model to eliminate microscopic disease in the post-surgical tumor bed and prevent local as well as metastatic recurrence.

MATERIALS AND METHODS

Athymic nude mice were orthotopically implanted with the human pancreatic cancer cell line BxPC3 expressing green fluorescent protein. After tumor engraftment, the mice were divided into two groups as follows: bright light surgery (BLS) + anti-CEA-IR700 + 690 nm laser (PIT); and BLS only. Anti-CEA-IR700 (100 μg) was administered to the treatment group via tail-vein injection 24 h before therapy. Tumors were resected, and the surgical bed was treated with intraoperative phototherapy at an intensity of 150 mW/cm(2) for 30 min. Mice were imaged noninvasively for 8 wk using an OV-100 small animal fluorescence imager.

RESULTS

BLS + PIT reduced local recurrence to 1/7 mice from 7/7 mice with BLS-only (P = 0.001) and metastatic recurrence to 2/7 mice compared with 6/7 mice with BLS-only (P = 0.03). Local tumor growth continued at a rapid rate after BLS-only compared with BLS + PIT where almost no local growth occurred. There was a significant difference in tumor size between mice in the BLS + PIT (2.14 mm(2), 95% confidence interval [CI] [-2.06 to 6.34] and BLS-only groups (115.2 mm(2), 95% CI [88.8-141.6]) at 6 wk after surgery (P < 0.001). There was also a significant difference in tumor weight between the BLS + PIT group (6.65 mg, 95% CI [-6.35 to 19.65] and BLS-only group (1100 mg, 95% CI [794-1406] at 8 wk after surgery (P < 0.001).

CONCLUSIONS

PIT holds promise in the treatment of pancreatic cancer and may serve as a useful adjunct to surgery in the eradication of microscopic residual disease that can lead to both local and metastatic recurrence. Further studies are warranted to investigate the potential toxicities of PIT, especially with regard to anastomoses, such as those involved in pancreaticoduodenectomy.

Photodynamic diagnosis for detection of peritoneal carcinomatosis

BACKGROUND

Peritoneal carcinomatosis is the dissemination of cancer in the peritoneal cavity secondary to abdominal or extra-abdominal malignancies. Accurate assessment of the disease's burden is a challenge because of the complexity of the peritoneal cavity and the small size of the metastatic nodules. Photodynamic diagnosis (PDD) is an emerging technology in tumor diagnosis. A photosensitizer is administered, which is preferentially taken up by cancer cells. The photosensitizer emits fluorescence when exposed to a light of a specific wavelength. This helps distinguish cancer from normal tissues.

METHODS

We systematically reviewed the evidence for using PDD in detecting peritoneal carcinomatosis in both animal and human literature. Both Medline and EMBASE databases were searched (November 2014). The titles and the abstracts of all retrieved citations were inspected, and the full articles of the relevant articles were obtained.

RESULTS

A total of 12 human and 18 animal studies were included. Clinical studies have shown PDD to be a safe modality with no significant adverse effects. It increases the detection of malignant peritoneal nodules by 21%-34% in comparison with white light alone. The sensitivity and specificity of PDD were reported at 83%-100% and 95%-100%, respectively. These findings were supported by multiple animal studies, which have shown an increase in the sensitivity of tumor detection when using PDD (72%-91%) in comparison with white light alone (39%).

CONCLUSIONS

PDD is a promising modality, which improves the detection of peritoneal carcinomatosis lesions. Further research, however, should investigate the impact of PDD on the patients' therapeutic management and final outcomes.

Fluorescence-guided surgery improves outcome in an orthotopic osteosarcoma nude-mouse model

In order to develop a model for fluorescence-guided surgery (FGS), 143B human osteosarcoma cells expressing red fluorescent protein (RFP) were injected into the intramedullary cavity of the tibia in nude mice. The fluorescent areas of residual tumors after bright-light surgery (BLS) and FGS were 10.2 ± 2.4 mm(2) and 0.1 ± 0.1 mm(2) , respectively (p<0.001). The BLS-treated mice and BLS+cisplatinum (CDDP)-treated mice had significant recurrence. In contrast, the FGS mice and FGS+CDDP mice had very little recurring tumor growth. Disease-free survival (DFS) in the BLS-, BLS+CDDP-, FGS-, and FGS+CDDP-treated mice was 12.5%, 37.5%, 75.0%, and 87.5%, respectively. The FGS-treated mice had a significantly higher DFS rate than the BLS-treated mice (p=0.021). The FGS+CDDP-treated mice had significantly higher DFS rate than the BLS+CDDP-treated mice (p=0.043). Although chemotherapy significantly reduced multiple metastases (p=0.033), there was no significant correlation between FGS and lung metastasis. FGS significantly reduced the recurrence of the primary tumor but did not reduce lung metastasis. The combination of FGS and adjuvant CDDP reduced tumor recurrence and prevented multiple metastases. FGS and adjuvant chemotherapy should be performed as early as possible in the disease to prevent both recurrence and metastatic development.

Fluorescence-guided surgery of prostate cancer bone metastasis

BACKGROUND

The aim of this study is to investigate the effectiveness of fluorescence-guided surgery (FGS) of prostate cancer experimental skeletal metastasis.

MATERIALS AND METHODS

Green fluorescent protein-expressing PC-3 human prostate cancer cells (PC-3-green fluorescent protein) were injected into the intramedullary cavity of the tibia in 32 nude mice. After 2 wk, 16 of the mice underwent FGS; the other 16 mice underwent bright-light surgery (BLS). Half of BLS and FGS mice (8 mice in each group) received zoledronic acid (ZOL). Weekly fluorescence imaging of the mice was performed. Six weeks after surgery, metastases to lung and inguinal lymph node were evaluated by fluorescence imaging.

RESULTS

The percentage of residual tumor after BLS and FGS was 9.9 ± 2.2% and 0.9 ± 0.3%, respectively (P < 0.001). FGS reduced recurrent cancer growth compared with BLS (P < 0.005). Although FGS alone had no significant effect on inguinal lymph node metastases, lung metastasis or disease-free survival (DFS), ZOL in combination with FGS significantly increased DFS (P = 0.01) in comparison with the combination of BLS and ZOL. ZOL reduced lymph node metastases (P = 0.033) but not lung metastasis.

CONCLUSIONS

FGS significantly reduced recurrence of experimental prostate cancer bone metastasis compared with BLS. The combination of FGS and ZOL increased DFS over BLS and ZOL. ZOL inhibited lymph node metastasis but not lung metastasis.

Ratiometric activatable cell-penetrating peptides label pancreatic cancer, enabling fluorescence-guided surgery, which reduces metastases and recurrence in orthotopic mouse models

BACKGROUND

The aim of this study was to evaluate the efficacy of using matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9)-cleavable ratiometric activatable cell-penetrating peptides (RACPPs) conjugated to Cy5 and Cy7 fluorophores to accurately label pancreatic cancer for fluorescence-guided surgery (FGS) in an orthotopic mouse model.

METHODS

Orthotopic mouse models were established using MiaPaCa-2-GFP human pancreatic cancer cells. Two weeks after implantation, tumor-bearing mice were randomized to conventional white light reflectance (WLR) surgery or FGS. FGS was performed at far-red and infrared wavelengths with a customized fluorescence-dissecting microscope 2 h after injection of MMP-2 and MMP-9-cleavable RACPPs. Green fluorescence imaging of the GFP-labeled cancer cells was used to assess the effectiveness of surgical resection and monitor recurrence. At 8 weeks, mice were sacrificed to evaluate tumor burden and metastases.

RESULTS

Mice in the WLR group had larger primary tumors than mice in the FGS group at termination [1.72 g ± standard error (SE) 0.58 vs. 0.25 g ± SE 0.14; respectively, p = 0.026). Mean disease-free survival was significantly lengthened from 5.33 weeks in the WLR group to 7.38 weeks in the FGS group (p = 0.02). Recurrence rates were lower in the FGS group than in the WLR group (38 vs. 73 %; p = 0.049). This translated into lower local and distant recurrence rates for FGS compared to WLR (31 vs. 67 for local recurrence, respectively, and 25 vs. 60 % for distant recurrence, respectively). Metastatic tumor burden was significantly greater in the WLR group than in the FGS group (96.92 mm(2) ± SE 52.03 vs. 2.20 mm(2) ± SE 1.43; respectively, χ (2) = 5.455; p = 0.02).

CONCLUSIONS

RACPPs can accurately and effectively label pancreatic cancer for effective FGS, resulting in better postresection outcomes than for WLR surgery.

Fluorescence-guided surgery in combination with UVC irradiation cures metastatic human pancreatic cancer in orthotopic mouse models

The aim of this study is to determine if ultraviolet light (UVC) irradiation in combination with fluorescence-guided surgery (FGS) can eradicate metastatic human pancreatic cancer in orthotopic nude–mouse models. Two weeks after orthotopic implantation of human MiaPaCa-2 pancreatic cancer cells, expressing green fluorescent protein (GFP), in nude mice, bright-light surgery (BLS) was performed on all tumor-bearing mice (n = 24). After BLS, mice were randomized into 3 treatment groups; BLS-only (n = 8) or FGS (n = 8) or FGS-UVC (n = 8). The residual tumors were resected using a hand-held portable imaging system under fluorescence navigation in mice treated with FGS and FGS-UVC. The surgical resection bed was irradiated with 2700 J/m² UVC (254 nm) in the mice treated with FGS-UVC. The average residual tumor area after FGS (n = 16) was significantly smaller than after BLS only (n = 24) (0.135±0.137 mm² and 3.338±2.929 mm², respectively; p = 0.007). The BLS treated mice had significantly reduced survival compared to FGS- and FGS-UVC-treated mice for both relapse-free survival (RFS) (p<0.001 and p<0.001, respectively) and overall survival (OS) (p<0.001 and p<0.001, respectively). FGS-UVC-treated mice had increased RFS and OS compared to FGS-only treated mice (p = 0.008 and p = 0.025, respectively); with RFS lasting at least 150 days indicating the animals were cured. The results of the present study suggest that UVC irradiation in combination with FGS has clinical potential to increase survival.

Polyethylene glycol (PEG) linked to near infrared (NIR) dyes conjugated to chimeric anti-carcinoembryonic antigen (CEA) antibody enhances imaging of liver metastases in a nude-mouse model of human colon cancer

We report here that polyethylene glycol (PEG) linked to near infrared dyes conjugated to chimeric mouse-human anti-carcinoembryonic antigen (CEA) antibody greatly improves imaging of liver metastases in a nude mouse model of colon-cancer experimental metastases. PEGylated and non-PEGylated DyLight 650 and 750 dyes were conjugated to the chimeric anti-CEA antibody. The dyes were initially injected intravenously into nude mice without tumors. Tissue biodistribution was determined by tissue sonication and analyzing tissue dye concentration profiles over time. PEGylated dyes had significantly lower accumulation in the liver (p = 0.03 for the 650 dyes; p = 0.002 for the 750 dyes) compared to non-PEGylated dyes. In an experimental liver metastasis model of HT-29 colon cancer, PEGylated dyes conjugated to the anti-CEA antibody showed good labeling of metastatic tumors with high contrast between normal and malignant tissue which was not possible with the non-PEGylated dyes since there was so much non-specific accumulation in the liver. PEGylation of the DyLight 650 and 750 NIR dyes significantly altered tissue biodistribution, allowing brighter tissue labeling, decreased accumulation in normal organs, particularly the liver. This enabled high fidelity and high contrast imaging of liver metastases.

Advantages of fluorescence-guided laparoscopic surgery of pancreatic cancer labeled with fluorescent anti-carcinoembryonic antigen antibodies in an orthotopic mouse model

BACKGROUND

Our laboratory has previously developed fluorescence-guided surgery of pancreatic and other cancers in orthotopic mouse models. Laparoscopic surgery is being used more extensively in surgical oncology. This report describes the efficacy of laparoscopic fluorescence-guided surgery of pancreatic cancer in an orthotopic mouse model.

STUDY DESIGN

Mouse models of human pancreatic cancer were established with fragments of the BxPC-3 red fluorescent protein-expressing human pancreatic cancer using surgical orthotopic implantation. Mice were randomized to bright-light laparoscopic surgery (BLLS) or to fluorescence-guided laparoscopic surgery (FGLS). Fluorescence-guided laparoscopic surgery was performed with a light-emitting diode light source through a 495-nm emission filter in order to resect the primary tumors and any additional separate submillimeter tumor deposits within the pancreas, the latter of which was not possible with BLLS. Tumors were labeled with anti-CEA AlexaFluor 488 antibodies 24 hours before surgery with intravenous injection. Perioperative fluorescence images were obtained to evaluate tumor size. Mice were followed postoperatively to assess for recurrence and at termination to evaluate tumor burden.

RESULTS

At termination, the FGLS-treated mice had less pancreatic tumor volume than the BLLS-treated mice (5.75 mm(2) vs 28.43 mm(2), respectively; p = 0.012) and lower tumor weight (21.1 mg vs 174.4 mg, respectively; p = 0.033). Fluorescence-guided laparoscopic surgery compared with BLLS also decreased local recurrence (50% vs 80%, respectively; p = 0.048) and distant recurrence (70% vs 95%, respectively; p = 0.046). More mice in the FGLS group than the BLLS group were free of tumor at termination (25% vs 5%, respectively). Median disease-free survival was lengthened from 2 weeks with BLLS (95% CI, 1.635-2.365) to 7 weeks with FGLS (95% CI, 5.955-8.045; p = 0.001).

CONCLUSIONS

Fluorescence-guided laparoscopic surgery is more effective than BLLS and, therefore, has important potential for surgical oncology.

[Further technical and digital development in minimally invasive and conventional surgery]

Technological innovations have initiated a fundamental change in invasive therapeutic approaches which has led to a welcome reduction of surgical trauma but was also associated with a declining role of conventional surgery. Active utilization of future technological developments is decisive to promote new therapeutic strategies and to avoid a further loss of importance of surgery. This includes individualized preoperative therapy planning as well as intraoperative diagnostic work-up and navigation and the use of new functional intelligent implants. The working environment "surgical operating room" has to be refurbished into an integrated cooperating functional system. The impact of new technological developments is particularly obvious in minimally invasive surgery. There is a clear tendency towards further reduction in trauma in the surgical access. The incision will become smaller and the number of ports will be further reduced, with the aim of ultimately having just one port (monoport surgery) or even via natural access routes (scarless surgery). Among others, improved visualization including, e.g. autostereoscopy, digital image processing and intelligent support systems, which are able to assist in a cooperative way, will enable these goals to be achieved.

Fluorescence-guided surgery with a fluorophore-conjugated antibody to carcinoembryonic antigen (CEA), that highlights the tumor, improves surgical resection and increases survival in orthotopic mouse models of human pancreatic cancer

BACKGROUND

We have developed a method of distinguishing normal tissue from pancreatic cancer in vivo using fluorophore-conjugated antibody to carcinoembryonic antigen (CEA). The objective of this study was to evaluate whether fluorescence-guided surgery (FGS) with a fluorophore-conjugated antibody to CEA, to highlight the tumor, can improve surgical resection and increase disease-free survival (DFS) and overall survival (OS) in orthotopic mouse models of human pancreatic cancer.

METHODS

We established nude-mouse models of human pancreatic cancer with surgical orthotopic implantation of the human BxPC-3 pancreatic cancer. Orthotopic tumors were allowed to develop for 2 weeks. Mice then underwent bright-light surgery (BLS) or FGS 24 h after intravenous injection of anti-CEA-Alexa Fluor 488. Completeness of resection was assessed from postoperative imaging. Mice were followed postoperatively until premorbid to determine DFS and OS.

RESULTS

Complete resection was achieved in 92 % of mice in the FGS group compared to 45.5 % in the BLS group (p = 0.001). FGS resulted in a smaller postoperative tumor burden (p = 0.01). Cure rates with FGS compared to BLS improved from 4.5 to 40 %, respectively (p = 0.01), and 1-year postoperative survival rates increased from 0 % with BLS to 28 % with FGS (p = 0.01). Median DFS increased from 5 weeks with BLS to 11 weeks with FGS (p = 0.0003). Median OS increased from 13.5 weeks with BLS to 22 weeks with FGS (p = 0.001).

CONCLUSIONS

FGS resulted in greater cure rates and longer DFS and OS using a fluorophore-conjugated anti-CEA antibody. FGS has potential to improve the surgical treatment of pancreatic cancer.

Specific tumor labeling enhanced by polyethylene glycol linkage of near infrared dyes conjugated to a chimeric anti-carcinoembryonic antigen antibody in a nude mouse model of human pancreatic cancer

Labeling of metastatic tumors can aid in their staging and resection of cancer. Near infrared (NIR) dyes have been used in the clinic for tumor labeling. However, there can be a nonspecific uptake of dye by the liver, lungs, and lymph nodes, which hinders detection of metastasis. In order to overcome these problems, we have used two NIR dyes (DyLight 650 and 750) conjugated to a chimeric anti-carcinoembryonic antigen antibody to evaluate how polyethylene glycol linkage (PEGylation) can improve specific tumor labeling in a nude mouse model of human pancreatic cancer. The conjugated PEGylated and non-PEGylated DyLight 650 and 750 dyes were injected intravenously into non-tumor-bearing nude mice. Serum samples were collected at various time points in order to determine serum concentrations and elimination kinetics. Conjugated PEGylated dyes had significantly higher serum dye concentrations than non-PEGylated dyes (p=0.005 for the 650 dyes and p<0.001 for the 750 dyes). Human pancreatic tumors subcutaneously implanted into nude mice were labeled with antibody-dye conjugates and serially imaged. Labeling with conjugated PEGylated dyes resulted in significantly brighter tumors compared to the non-PEGylated dyes (p<0.001 for the 650 dyes; p=0.01 for 750 dyes). PEGylation of the NIR dyes also decreased their accumulation in lymph nodes, liver, and lung. These results demonstrate enhanced selective tumor labeling by PEGylation of dyes conjugated to a tumor-specific antibody, suggesting their future clinical use in fluorescence-guided surgery.

In vivo fluorescence imaging of gastrointestinal stromal tumors using fluorophore-conjugated anti-KIT antibody

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are frequently characterized by KIT overexpression. Tumor-free margins and complete cytoreduction of disease are mainstays of treatment. We hypothesized that fluorescently labeled anti-KIT antibodies can label GIST in vivo.

METHODS

KIT K641E(+/-) transgenic mice that spontaneously develop cecal GISTs were used in this study, with C57BL/6 mice serving as controls. Alexa 488 fluorophore-conjugated anti-KIT antibodies were delivered via the tail vein 24 h prior to fluorescence imaging. Following fluorescence laparoscopy, mice were sacrificed. The gastrointestinal tracts were grossly examined for tumors followed by fluorescence imaging. Tumors were harvested for histologic confirmation.

RESULTS

KIT K641E(+/-) mice and C57BL/6 control mice received anti-KIT antibody or isotope control antibody. Fluorescence laparoscopy had a high tumor signal-to-background noise ratio. Upon blinded review of intravital fluorescence and bright light images, there were 2 false-positive and 0 false-negative results. The accuracy was 92 %. The sensitivity, specificity, positive and negative predictive values were 100, 87, 85, and 100 %, respectively, for the combined modalities.

CONCLUSIONS

In this study, we present a method for in vivo fluorescence labeling of GIST in a murine model. Several translatable applications include: laparoscopic staging; visualization of peritoneal metastases; assessment of margin status; endoscopic differentiation of GISTs from other benign submucosal tumors; and longitudinal surveillance of disease response. This novel approach has clear clinical applications that warrant further research and development.

Comparison of a chimeric anti-carcinoembryonic antigen antibody conjugated with visible or near-infrared fluorescent dyes for imaging pancreatic cancer in orthotopic nude mouse models

The aim of this study was to evaluate a set of visible and near-infrared dyes conjugated to a tumor-specific chimeric antibody for high-resolution tumor imaging in orthotopic models of pancreatic cancer. BxPC-3 human pancreatic cancer was orthotopically implanted into pancreata of nude mice. Mice received a single intravenous injection of a chimeric anti-carcinoembryonic antigen antibody conjugated to one of the following fluorophores: 488-nm group (Alexa Fluor 488 or DyLight 488); 550-nm group (Alexa Fluor 555 or DyLight 550); 650-nm group (Alexa Fluor 660 or DyLight 650), or the 750-nm group (Alexa Fluor 750 or DyLight 755). After 24 h, the Olympus OV100 small-animal imaging system was used for noninvasive and intravital fluorescence imaging of mice. Dyes were compared with respect to depth of imaging, resolution, tumor-to-background ratio (TBR), photobleaching, and hemoglobin quenching. The longer wavelength dyes had increased depth of penetration and ability to detect the smallest tumor deposits and provided the highest TBRs, resistance to hemoglobin quenching, and specificity. The shorter wavelength dyes were more photostable. This study showed unique advantages of each dye for specific cancer imaging in a clinically relevant orthotopic model.

Fluorescently labeled chimeric anti-CEA antibody improves detection and resection of human colon cancer in a patient-derived orthotopic xenograft (PDOX) nude mouse model

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate a new fluorescently labeled chimeric anti-CEA antibody for improved detection and resection of colon cancer.

METHODS

Frozen tumor and normal human tissue samples were stained with chimeric and mouse antibody-fluorophore conjugates for comparison. Mice with patient-derived orthotopic xenografts (PDOX) of colon cancer underwent fluorescence-guided surgery (FGS) or bright-light surgery (BLS) 24 hr after tail vein injection of fluorophore-conjugated chimeric anti-CEA antibody. Resection completeness was assessed using postoperative images. Mice were followed for 6 months for recurrence.

RESULTS

The fluorophore conjugation efficiency (dye/mole ratio) improved from 3-4 to >5.5 with the chimeric CEA antibody compared to mouse anti-CEA antibody. CEA-expressing tumors labeled with chimeric CEA antibody provided a brighter fluorescence signal on frozen human tumor tissues (P = 0.046) and demonstrated consistently lower fluorescence signals in normal human tissues compared to mouse antibody. Chimeric CEA antibody accurately labeled PDOX colon cancer in nude mice, enabling improved detection of tumor margins for more effective FGS. The R0 resection rate increased from 86% to 96% with FGS compared to BLS.

CONCLUSION

Improved conjugating efficiency and labeling with chimeric fluorophore-conjugated antibody resulted in better detection and resection of human colon cancer in an orthotopic mouse model.

Hand-held high-resolution fluorescence imaging system for fluorescence-guided surgery of patient and cell-line pancreatic tumors growing orthotopically in nude mice

BACKGROUND

In this study, we investigated the advantages of fluorescence-guided surgery (FGS) in mice of a portable hand-sized imaging system compared with a large fluorescence imaging system or a long-working-distance fluorescence microscope.

METHODS

Mouse models of human pancreatic cancer for FGS included the following: (1) MiaPaCa-2-expressing green fluorescent protein, (2) BxPC3 labeled with Alexa Fluor 488-conjucated anti-carcinoembryonic antigen (CEA) antibody, and (3) patient-derived orthotopic xenograft (PDOX) labeled with Alexa Fluor 488-conjugated anti-carbohydrate antigen 19-9 antibody.

RESULTS

Each device could clearly detect the primary MiaPaCa-2-green fluorescent protein tumor and any residual tumor after FGS. In the BxPC3 model labeled with Alexa Fluor 488-conjugated anti-CEA, each device could detect the primary tumor, but the MVX10 could not clearly detect the residual tumor remaining after FGS whereas the other devices could. In the PDOX model labeled with Alexa Fluor 488-conjugated anti-carbohydrate antigen 19-9, only the portable hand-held device could distinguish the residual tumor from the background, and complete resection of the residual tumor was achieved under fluorescence navigation.

CONCLUSIONS

The results described in the present report suggest that the hand-held mobile imaging system can be applied to the clinic for FGS because of its convenient size and high sensitivity which should help make FGS widely used.

Fluorescence-guided surgery and fluorescence laparoscopy for gastrointestinal cancers in clinically-relevant mouse models

There are many challenges that face surgeons when attempting curative resection for gastrointestinal cancers. The ability to properly delineate tumor margins for complete resection is of utmost importance in achieving cure and giving the patient the best chance of prolonged survival. Targeted tumor imaging techniques have gained significant interest in recent years to enable better identification of tumor lesions to improve diagnosis and treatment of cancer from preoperative staging modalities to optimizing the surgeon's ability to visualize tumor margins at the initial operation. Using unique characteristics of the tumor to fluorescently label the tissue can delineate tumor margins from normal surrounding tissue, allowing improved precision of surgical resection. In this paper, different methods of fluorescently labeling native tumor are discussed as well as the development of fluorescence laparoscopy and the potential role for fluorescence-guided surgery in the treatment of gastrointestinal cancers.

Fluorescence-guided surgery of human colon cancer increases complete resection resulting in cures in an orthotopic nude mouse model

BACKGROUND

We inquired if fluorescence-guided surgery (FGS) could improve surgical outcomes in fluorescent orthotopic nude mouse models of human colon cancer.

METHODS

We established fluorescent orthotopic mouse models of human colon cancer expressing a fluorescent protein. Tumors were resected under bright light surgery (BLS) or FGS. Pre- and post-operative images with the OV-100 Small Animal Imaging System (Olympus Corp, Tokyo Japan) were obtained to assess the extent of surgical resection.

RESULTS

All mice with primary tumor that had undergone FGS had complete resection compared with 58% of mice in the BLS group (P = 0.001). FGS resulted in decreased recurrence compared with BLS (33% versus 62%, P = 0.049) and lengthened disease-free median survival from 9 to >36 wk. The median overall survival increased from 16 wk in the BLS group to 31 weeks in the FGS group. FGS resulted in a cure in 67% of mice (alive without evidence of tumor at >6 mo after surgery) compared with only 37% of mice that underwent BLS (P = 0.049).

CONCLUSIONS

Surgical outcomes in orthotopic nude mouse models of human colon cancer were significantly improved with FGS. The present study can be translated to the clinic by various effective methods of fluorescently labeling tumors.