Fluorescence-guided surgery of prostate cancer bone metastasis

Imidazole fused phenanthroline (PIP) ligands for the preparation of multimodal Re(I) and 99mTc(I) probes

A small library of [2 + 1] 99mTc(i) complexes based on phenyl-imidazole-fused phenanthroline (PIP) ligands were synthesized and evaluated as multimodal molecular imaging probes. Using either a two-step or a one-pot synthesis method, 99mTc-PIP complexes containing N-methylimidazole as the monodentate ligand were prepared and isolated in good (54 to 89%) radiochemical yield, with the exception of one derivative bearing a strongly electron-withdrawing substituent. The stability of the [2 + 1] complexes was assessed in saline and in cysteine and histidine challenge studies, showing 6 hours stability, making them suitable for in vivo studies. In parallel, the Re(i) analogues were prepared as reference standards to verify the structure of the 99mTc complexes. The optical properties were consistent with other previously reported [2 + 1] type Re(i) complexes that have been used as cellular dyes and sensors. To facilitate the development of targeted derivatives, a tetrazine-PIP ligand was also synthesized. The 99mTc complex of the tetrazine PIP ligand effectively coupled to compounds containing a trans-cyclooctene (TCO) group including a TCO-albumin derivative, which was prepared as a model targeting molecule. An added benefit of the Re-PIP-Tz construct is that the emission from the metal complex was quenched by the presence of the tetrazine. Following the addition of TCO, there was a 70-fold increase in fluorescence emission, which can in future be leveraged during in vitro studies to reduce background signal.

Oral recombinant methioninase combined with oxaliplatinum and 5-fluorouracil regressed a colon cancer growing on the peritoneal surface in a patient-derived orthotopic xenograft mouse model

The aim of this study was to determine the efficacy of oral recombinant methioninase (o-rMETase) on a model of colon cancer growing on the peritoneal surface using a patients-derived orthotopic xenograft (PDOX) nude mouse model. Forty PDOX mouse models with colon cancer growing on the peritoneum were divided into 4 groups of 10 mice each by measuring the tumor size and fluorescence intensity: untreated control; 5-fluorouracil (5-FU) (50 mg/kg, once a week for two weeks, ip) and oxaliplatinum (OXA) (6  mg/kg, once a week for two weeks, ip); o-rMETase (100 units/day, oral 14 consecutive days); combination 5-FU + OXA and o-rMETase. All treatments inhibited tumor growth compared to the untreated control. The combination of 5-FU + OXA plus o-rMETase was significantly more efficacious than the control and each drug alone and was the only treatment that caused tumor regression. The present study is the first demonstrating the efficacy of o-rMETase combination therapy on a PDOX model of peritoneal colon cancer, suggesting potential clinical development of o-rMETase in a recalcitrant cancer.

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.

Practical use of imaging technique for management of bone and soft tissue tumors

Imaging modalities including radiography, computed tomography (CT), and magnetic resonance imaging (MRI) are necessary for the diagnosis of bone and soft tissue tumors. The history of imaging began with the discovery of X-rays in the 19th century. The development of CT, MRI, ultrasonography, and positron emission tomography (PET) have improved the management of bone and soft tissue tumors. X-ray imaging and CT scans enable the evaluation of bone destruction, periosteal reaction, sclerotic changes in lesions, condition of cortical bone, and ossification. MRI enables the assessment of tissue characteristics, tumor extent, and the reactive areas. Functional imaging modalities including ²⁰¹thallium (²⁰¹Tl) scintigraphy can be used to differentiate benign lesions from malignant lesions and to assess chemotherapeutic effects. Real-time assessment of soft tissue tumors by ultrasonography enables accurate and safe performance of surgery and biopsy. This article describes useful imaging modalities and characteristic findings in the management of bone and soft tissue tumors.

Effective fluorescence-guided surgery of liver metastasis using a fluorescent anti-CEA antibody

BACKGROUND AND OBJECTIVES

Delineation of adequate tumor margins is critical in oncologic surgery, particularly in resection of metastatic lesions. Surgeons are limited in visualization with bright-light surgery, but fluorescence-guided surgery (FGS) has been efficacious in helping the surgeon achieve negative margins.

METHODS

The present study uses FGS in a mouse model that has undergone surgical orthotopic implantation (SOI) of colorectal liver metastasis tagged with green fluorescent protein (GFP). An anti-CEA antibody conjugated to DyLight 650 was used to highlight the tumor.

RESULTS

The fluorescent antibody clearly demarcated the lesion at deeper tissue depth compared to GFP. Fluorescence of the anti-CEA-DyLight650 showed maximal tumor-to-liver contrast at 72 hr. Fifteen mice underwent bright-light surgery (BLS) versus FGS with GFP versus FGS with anti-CEA-DyLight650. Mice that underwent FGS had a significantly smaller area of residual tumor (P < 0.001) and significantly longer overall survival (P < 0.001) and disease-free survival (P < 0.001). Within the two FGS groups, mice undergoing surgery with anti-CEA-DyLight650 improved survival compared to only GFP labeling.

CONCLUSIONS

In the present report, we demonstrate that an anti-CEA antibody conjugated to a DyLight 650 nm dye clearly labeled colon cancer liver metastases, thereby enabling successful FGS. J. Surg. Oncol. 2016;114:951-958. © 2016 Wiley Periodicals, Inc.

Efficacy of Tumor-Targeting Salmonella A1-R on a Melanoma Patient-Derived Orthotopic Xenograft (PDOX) Nude-Mouse Model

Tumor-targeting Salmonella enterica serovar Typhimurium A1-R (Salmonella A1-R) had strong efficacy on a melanoma patient-derived orthotopic xenograft (PDOX) nude-mouse model. GFP-expressing Salmonella A1-R highly and selectively colonized the PDOX melanoma and significantly suppressed tumor growth (p = 0.021). The combination of Salmonella A1-R and cisplatinum (CDDP), both at low-dose, also significantly suppressed the growth of the melanoma PDOX (P = 0.001). Salmonella A1-R has future clinical potential for combination chemotherapy with CDDP of melanoma, a highly-recalcitrant cancer.

Real-Time In Vivo Confocal Fluorescence Imaging of Prostate Cancer Bone-Marrow Micrometastasis Development at the Cellular Level in Nude Mice

In the present report, we demonstrate in vivo fluorescence imaging of bone-marrow micrometastasis of prostate cancer at the cellular level in nude mice. PC-3 human prostate cancer cells labeled with green fluorescent protein (GFP) or red fluorescent protein (RFP) were injected into the left ventricle or intratibial bone marrow of nude mice. PC-3-GFP, as well as selected high metastatic variants of PC-3-GFP, PC-3-GFP-BM6 or PC-3-RFP were visualized by real-time fluorescence imaging, to traffic and grow in the bone marrow. Formation of bone marrow micrometastasis could be imaged at the single-cell level in live mice, using confocal microscopy. The ability to track bone marrow micrometastasis in real time at the cellular level provides a visual target for evaluating new therapeutics for this recalcitrant disease. J. Cell. Biochem. 117: 2533-2537, 2016. © 2016 Wiley Periodicals, Inc.

New therapeutic targets for cancer bone metastasis

Bone metastases are dejected consequences of many types of tumors including breast, prostate, lung, kidney, and thyroid cancers. This complicated process begins with the successful tumor cell epithelial-mesenchymal transition, escape from the original site, and penetration into the circulation. The homing of tumor cells to the bone depends on both tumor-intrinsic traits and various molecules supplied by the bone metastatic niche. The colonization and growth of cancer cells in the osseous environment, which awaken their dormancy to form micro- and macro-metastasis, involve an intricate interaction between the circulating tumor cells and local bone cells including osteoclasts, osteoblasts, adipocytes, and macrophages. We discuss the most recent advances in the identification of new molecules and novel mechanisms during each step of bone metastasis that may serve as promising therapeutic targets.

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.