Mapping lymph nodes in cancer management - role of (99m)Tc-tilmanocept injection

Comparative aspects of targeted sentinel lymph node mapping in veterinary and human medicine: opportunities for future research

There is a significant overlap in the genetic, metabolic and epigenetic alterations between human and companion animal cancers, including those of the oral cavity, breast, bladder, skin, lungs and pancreas. In many cancer types, the identification and removal of affected lymph nodes are essential for accurate cancer management, including treatment and prognosis. Historically, lymphadenectomy and subsequent radical resection based on regional anatomy, palpation and lymph node aspirates were considered sufficient; however, modern approaches with sentinel lymph node mapping (SLN) mapping have increased the accuracy of surgical decision-making. Preoperative and intraoperative SLN mapping techniques in veterinary patients parallel those used in human medicine. While many of these techniques are highly successful, the main challenges with current methodologies are their sensitivity and specificity for the presence of cancer, which can be overcome via precision medicine and targeted SLN mapping agents. Given the large population of dogs and cats with cancer, the crossover of knowledge between species can help to deepen our understanding of many of these cancers and can be useful in evaluating new drugs and/or therapies. In this review, we discuss SLN mapping techniques in veterinary medicine and the concept of precision medicine as it relates to targeted SLN mapping imaging agents. The large number of companion animals affected by cancer is an underutilized resource to bridge the translational gap and we aim to provide a reference for the use of dogs and cats as a comparative model for human SLN mapping.

99mTc-Tilmanocept vs. Sulfur Colloid for Sentinel Node Biopsy for Melanoma in the Head and Neck

The objective of the study is to compare sentinel lymph node (SLN) identification rates and performance characteristics of lymphoscintigraphy using 99mTc-sulfur colloid (SC) and 99mTc-tilmanocept (TL) for head and neck cutaneous melanoma. This study is a retrospective study, conducted at a single, tertiary care cancer center. Patients underwent sentinel lymph node biopsy (SLNB) for head and neck cutaneous melanoma, using SC or TL, between October 2014 and February 2019. Differences in SLN identification rates and performance characteristics between the groups were examined using the Mann-Whitney, or Fisher's exact test. Sixty patients underwent SLNB, of which 19 employed TL. There were no significant differences between SC vs. TL in operative duration (116 vs. 127 min, P = 0.97), radiation dose (530 vs. 547 μCi, P = 0.27), median number of SLNs removed (3 vs. 2, P = 0.32), or median follow-up (46.3 vs. 38.4 months, P = 0.11). The rates of positive SLNs (17% vs. 37%, P = 0.11), intraoperative non-localization (12% vs. 16%, P = 0.70), and false-negative SLNB (5% each, P = 1.00) were not significantly different between groups. In patients with head and neck melanoma undergoing SLNB, 99mTc-tilmanocept may not differ from 99mTc-sulfur colloid in identifying SLNs or other performance characteristics. The added expense related to 99mTc-tilmanocept and lack of favorable performance data should urge caution in its adoption and promote further examination of its value in similar patient cohorts.

Applications and Safety of Sentinel Lymph Node Biopsy in Endometrial Cancer

Lymph node status is important in predicting the prognosis and guiding adjuvant treatment in endometrial cancer. However, previous studies showed that systematic lymphadenectomy conferred no therapeutic values in clinically early-stage endometrial cancer but might lead to substantial morbidity and impact on the quality of life of the patients. The sentinel lymph node is the first lymph node that tumor cells drain to, and sentinel lymph node biopsy has emerged as an acceptable alternative to full lymphadenectomy in both low-risk and high-risk endometrial cancer. Evidence has demonstrated a high detection rate, sensitivity and negative predictive value of sentinel lymph node biopsy. It can also reduce surgical morbidity and improve the detection of lymph node metastases compared with systematic lymphadenectomy. This review summarizes the current techniques of sentinel lymph node mapping, the applications and oncological outcomes of sentinel lymph node biopsy in low-risk and high-risk endometrial cancer, and the management of isolated tumor cells in sentinel lymph nodes. We also illustrate a revised sentinel lymph node biopsy algorithm and advocate to repeat the tracer injection and explore the presacral and paraaortic areas if sentinel lymph nodes are not found in the hemipelvis.

A Prospective Double-Blinded Randomized Controlled Trial Comparing the Intraoperative Injection of Technetium Tc 99m Tilmanocept with Technetium Tc 99m Sulfur Colloid in Breast Cancer Lymphatic Mapping

Introduction. Technetium-labeled sulfur colloid (TSC) is a radiolabeled mapping agent commonly used for sentinel lymph node biopsy (SLNBx). Tilmanocept, a CD206 receptor-targeted mapping agent, has gained recent popularity due to potential advantages of rapid and quick uptake to the SLNs. The objectives of this study were to assess (1) the difference in the number of SLNs harvested using tilmanocept versus TSC and (2) the difference in time to transcutaneous localization when using an intraoperative injection approach. Methods. Patients undergoing breast conservation and SLNBx were consented and randomized to receive either 0.5 mCi of filtered TSC or 0.5 mCi of tilmanocept injected intradermally immediately after induction of anesthesia. Axillary transcutaneous gamma detector probe counts were taken at 1-minute intervals until a hot spot was identified. SLNs were then identified and excised. Additional nodes were excised if their counts per second (cps) were greater than 10% of the cps of the hottest SLN. The number of SLNs was based on both number of nodes collected intraoperatively and the number recorded in the final pathology report. Results. The study population consisted of 86 patients, 48 randomized to tilmanocept and 38 to TSC. There were no significant differences in patient or tumor characteristics between the two groups. Localization rates were 100% for both cohorts. The mean number of SLNs identified and removed was not significantly different ( $p=0.34$ , intraoperatively; $p=0.57$ , pathology reported). Time to transcutaneous localization was 3.3 ± 2.0 minutes for tilmanocept and 3.9 ± 2.3 minutes for TSC ( $p=0.19$ ). The average cps for the hottest node was 2,180.0 ± 2,460.5 in the tilmanocept group compared to 2,679.3 ± 2,687.5 in the TSC group ( $p=0.94$ ). Conclusion. There was no significant difference in the number of SLNs harvested or in the time to transcutaneous localization when using tilmanocept versus TSC as the radiolabeled mapping agents for intraoperative injection and mapping. Either agent can be used without any significant difference in performance.

Sentinel Lymph Node Mapping: Current Applications and Future Perspectives in Gynecology Malignant Tumors

The sentinel lymph nodes (SLNs) is a group of lymph nodes initially involved in the metastatic spread of cancer cells. SLN mapping refers to intraoperative localization and biopsy of SLNs with specific tracers to assess lymph node metastases. It is widely used in a variety of tumor surgeries for its high sensitivity and high negative predictive value. In the evaluation of the status of lymph node metastases in gynecological malignancies, it has received increasingly more attention due to its minor invasiveness, few complications, and high diagnosis rate. The National Comprehensive Cancer Network (NCCN) guidelines provide an excellent introduction to the indications and methods of SLN techniques in vulvar, cervical, and endometrial cancers, but they provide little explanation about some specific issues. In this review, we summarize different dyes and injection methods and discuss the indications of application and the clinical trials of SLN mapping in gynecological malignant tumors, aiming to provide a reference for the rational application of sentinel techniques in gynecology malignant tumors before relevant guidelines are updated.

Initial experience with targeted axillary dissection after neoadjuvant therapy in breast cancer patients

Background

Targeted axillary dissection (TAD) combines sentinel node biopsy (SNB) with the removal of the previously marked metastatic node. TAD is a promising concept for axillary restaging in node-positive breast cancer patients with pathological complete response (pCR) to neoadjuvant therapy (NAT). We aimed to evaluate TAD feasibility in this context.

Methods

A prospective observational study was conducted in biopsy-confirmed cN1 patients. The removal of the clipped node (CN) was guided by intraoperative ultrasound. SNB used indocyanine green and patent blue V dye. If the CN or sentinel lymph nodes (SLN) had any metastatic foci, or the TAD procedure was unsuccessful, the patient underwent axillary lymph node dissection (ALND).

Results

Thirty-seven patients were included. TAD and SNB identification rates were 97.3%. Every retrieved CN was also a SLN. At the individual level, SNB identification rate was 89.2% with indocyanine green and 85.5% with patent blue V dye. The CN identification rate was 81.1%, being higher when the CN was localized on the intraoperative ultrasound (84.4% vs 60.0%). Nodal pCR was achieved by 54.1% of our patients and was more frequent in HER2-positive and triple-negative tumors (p = 0.039). Nineteen patients were spared from ALND.

Conclusion

TAD with intraoperative ultrasound-guided excision of the CN and SNB with indocyanine green and patent blue V dye is a feasible concept to identify patients without axillary residual disease after NAT, that can be spared from ALND, although the need for marking the biopsied node should be further investigated.

Contemporary update of SPECT tracers and novelties in radioguided surgery: a perspective based on urology

Recent technical advances and implementation of novel radiotracers have further increased the potential of radioguided surgery for a broad variety of malignancies. Indeed, the possibilities for future applications of novel radiotracers in diverse oncological strategies has become more promising than ever. This literature review aims to provide a contemporary update on a selected group of radiotracers and evaluates the usability of radioguided surgery and sentinel node procedures, focusing on most promising advances. For example, the impact of targeted radiotracers on prostate specific membrane antigen (PSMA), CD206 receptor-targeted agents (^99mTc-tilmanocept), and hybrid tracers adding fluorescence to radioguidance (ICG-^99mTc-nanocolloid) as well as targeting hypoxia-induced carbonic anhydrase IX (CAIX) will be covered. Furthermore, future outlooks on the implementation of gold nanoparticles (AuNP's), but also technical advances in improved radiotracer detection by hybrid gamma devices will be discussed.

Cutaneous adverse effects of methylene blue in an animal skin-flap model

Background and objectives: Sentinel lymph node biopsy is important for metastasis surveillance in the management of a number of human cancers. Identification of sentinel lymph nodes may be facilitated by the use of several methods including methylene blue injection. However tissue necrosis is a known effect of methylene blue application. This study aimed to investigate the effects of methylene blue injection on skin flaps using a rodent model.Methods: Modified McFarlane flaps were prepared using Wistar Albino rats. Local injection of methylene blue was given to one group while saline was injected into the control group. A third group received systemic methylene blue via intraperitoneal injection. Observational and histological comparison was made between the groups to investigate the necrotic effects of methylene blue on skip flaps.Results: The control group's surviving flap areas were significantly larger than local methylene blue group's surviving flap area. However, there was no significant difference in skin flap survival area between the control group and the systemic methylene blue group. Furthermore, there is no significant difference between local and systemic methylene blue group's surviving flap areas.Conclusions: Local methylene blue injection increases skin necrosis and decreases rates of surviving flap areas in an experimental rat models.

Mannan-based conjugates as a multimodal imaging platform for lymph nodes

We show that mannan-based conjugates possess exceptional features for multimodal imaging because of their biocompatibility, biodegradability and self-targeting properties. Two new mannan conjugates, containing a gadolinium complex and a fluorescent probe, one based only on polysaccharide and the other one comprising polysaccharide with poly(2-methyl-2-oxazoline) grafts, were prepared and simultaneously visualized in vitro and in vivo by magnetic resonance and fluorescence imaging. The synthesis of these mannan-based complexes was based on alkylation with allyl bromide or grafting with poly(2-methyl-2-oxazoline) chains, followed by a thiol-ene click reaction with cysteamine to introduce primary amino groups into their structure. Finally, the obtained conjugates were functionalized with contrast labels using the corresponding N-hydroxysuccinimide esters. When used to detect lymph nodes, the polymers showed better imaging properties than a commercially available contrast agent.

[Application of carbon nanoparticles as lymph node tracers in patients with cN0 lingual squamous cell carcinoma un-dergoing neck dissection]

OBJECTIVE

This study aimed to investigate the value of carbon nanoparticles as lymph node tracers in neck dissection for cN0 lingual squamous cell carcinoma patients.

METHODS

Ninety-six patients with cN0 lingual squamous cell carcinoma were recruited to undergo surgical treatment were randomly divided into two groups, namely, the carbon nanoparticle-labeled group (the experimental group, 50 cases) and the control group (46 cases). Carbon nanoparticle suspension was injected into the submucosal layer around the site of the primary tumor at three or four points (0.1 mL for each point) 12 h before surgery. Supraomohyoid neck dissection (SOHND, Levels Ⅰ to Ⅲ) or comprehensive neck dissection (CND, Levels Ⅰto Ⅴ) were performed based on the size and location of the primary tumor. All the lymph nodes were dissected and separated from the ex vivo surgical specimens for histopathological evaluation. The number, size, location, and pathological result of all the lymph nodes were compared between the two groups. Statistical analyses were conducted by SPSS 19.0 software.

RESULTS

A total of 1 137 lymph nodes were detected in 31 SOHND patients. The average number of lymph nodes detected in the experimental group was (43.79±19.23) /case, which was significantly higher than that in the control group [(30.82±8.77) /case] (P=0.019). Level Ⅲ covered the largest number of lymph nodes in the two groups. However, the number and proportion of lymph nodes found in Level Ⅱ of the experimental group were significantly higher than those of the control group (P=0.000). A total of 3 938 lymph nodes were detected in 65 CND patients. The average number of lymph nodes detected in the experimental group [(66.67±20.02) /case] was larger than that in the control group [(53.03±20.98) /case] (P=0.026). The difference in the lymph node location between the two groups was not statistically significant (P=0.354). In the two neck dissection methods, both the proportion of minute lymph nodes and the accuracy of the detected lymph nodes in the experimental group were significantly larger than those in the control groups (P=0.000). Compared with the control group, more metastases were proven by the carbon nanoparticle-labeled lymph nodes (P=0.000) in the experimental group.

CONCLUSIONS

Carbon nanoparticles as lymph node tracers in patients with cN0 lingual squamous cell carcinoma undergoing neck dissection can increase the number of detected lymph nodes, especially the minute nodes. Such nanoparticles can further ensure the thoroughness of neck dissection and the accuracy of clinicopathological stage.

Mapping Sentinel Lymph Node Metastasis by Dual-probe Optical Imaging

Purpose: Sentinel lymph node biopsy (SLNB) has emerged as the preferred standard procedure in patients with breast cancer, melanoma and other types of cancer. Herein, we developed a method to intra-operatively map SLNs and differentiate tumor metastases within SLNs at the same time, with the aim to provide more accurate and real-time intraoperative guidance. Experimental Design: Hyaluronic acid (HA), a ligand of lymphatic vessel endothelial hyaluronan receptor (LYVE)-1, is employed as a SLN mapping agent after being conjugated with a near-infrared fluorophore (Cy5.5). Different sized HAs (5, 10 and 20K) were tested in normal mice and mice with localized inflammation to optimize LN retention time and signal to background ratio. Cetuximab, an antibody against epidermal growth factor receptor (EGFR), and trastuzumab, an antibody against human epidermal growth factor receptor 2 (HER2), were labeled with near-infrared fluorophore (IRDye800) for detecting metastatic tumors. LN metastasis model was developed by hock injection of firefly luciferase engineered human head neck squamous carcinoma cancer UM-SCC-22B cells or human ovarian cancer SKOV-3 cells. The metastases within LNs were confirmed by bioluminescence imaging (BLI). IRDye800-Antibodies were intravenously administered 24 h before local administration of Cy5.5-HA. Optical imaging was then performed to identify nodal metastases. Results: Binding of HA with LYVE-1 was confirmed by ELISA and fluorescence staining. HA with a size of 10K was chosen based on the favorable migration and retention profile. After sequential administration of IRDye800-antibodies intravenously and Cy5.5-HA locally to a mouse model with LN metastases and fluorescence optical imaging, partially metastasized LNs were successfully distinguished from un-metastasized LNs and fully tumor occupied LNs, based on the different signal patterns. Conclusions: Fluorophore conjugated HA is a potential lymphatic mapping agent for SLNB. Dual-tracer imaging with the combination of lymphatic mapping agents and tumor targeting agents can identify tumor metastases within SLNs, thus may provide accurate and real-time intra-operative guidance to spare the time spent waiting for a biopsy result.

Sentinel lymph node surgery after neoadjuvant chemotherapy in patients with T2 to T4, N0 and N1 breast cancer

BACKGROUND

Histological status of axillary lymph nodes is an important prognostic factor in patients receiving surgery for breast cancer (BC). Sentinel lymph node (SLN) biopsy (B) has rapidly replaced axillary lymph node dissection (ALND), and is now the standard of care for axillary staging in patients with clinically node-negative (N0) operable BC. The aim of this study is to compare pretreatment lymphoscintigraphy with a post primary systemic treatment (PST) scan in order to reduce the false-negative rates for SLNB.

METHODS

In this single-institution study we considered 170 consecutive T2-4 N0-1 M0 BC patients treated with anthracycline-based PST. At the time of incisional biopsy, we performed sentinel lymphatic mapping. After PST, all patients repeated lymphoscintigraphy with the same methodology. During definitive surgery we performed further sentinel lymphatic mapping, SLNB and ALND.

RESULTS

The SLN was removed in 158/170 patients giving an identification rate of 92.9% (95% confidence interval (CI) = 88.0-96.3%) and a false-negative rate of 14.0% (95% CI = 6.3-25.8%). SLNB revealed a sensitivity of 86.0% (95% CI = 74.2-93.7%), an accuracy of 94.9% (95% CI = 90.3-97.8%) and a negative predictive value of 92.7% (95% CI = 86.1-96.8%).

CONCLUSION

Identification rate, sensitivity and accuracy are in accordance with other studies on SLNB after PST, even after clinically negative node conversion following PST. This study confirms that diagnostic biopsy and neoadjuvant chemotherapy maintain breast lymphatic drainage unaltered.

64 CuS-labeled nanoparticles: a new sentinel-lymph-node-mapping agent for PET-CT and photoacoustic tomography

Determining sentinel lymph node (SLN) status is critical to cancer staging and treatment decisions. Currently, in clinical practice, ^99m Tc-radiocolloid-mediated planar scintigraphy and single-photon emission computed tomography (SPECT) are used to guide the biopsy and resection of SLNs. Recently, an emerging technique that combines positron emission tomography (PET) and photoacoustic tomography (PAT; PET-PAT) may offer accurate information in detecting SLNs. Herein, we report a kind of ⁶⁴ CuS-labeled nanoparticle (⁶⁴ CuS-NP) for the detection of SLNs with PET-PAT. We subcutaneously injected ⁶⁴ CuS-NPs into the rats' forepaw pads. After 24 h, the rats' first draining axillary lymph nodes (i.e. the SLNs) could be clearly visualized with micro-PET (μPET)-CT. Rats were sacrificed after μPET-CT imaging, their axillary lymph nodes were surgically identified, and then PAT was employed to discover ⁶⁴ CuS-NP-avid SLNs, which were embedded inside tissues. Biodistribution, autoradiography, and copper staining analyses confirmed the SLNs' high uptake of ⁶⁴ CuS-NPs. Our study indicates that ⁶⁴ CuS-NPs are a promising dual-function agent for both PET-CT and PAT and could be used with multi-modal imaging strategies such as PET-PAT to identify SLNs in a clinical setting. Copyright © 2016 John Wiley & Sons, Ltd.

Technetium-99m-labeled rituximab for use as a specific tracer of sentinel lymph node biopsy: a translational research study

PURPOSE

We aimed to develop and translate a CD20-antigen-targeted radiopharmaceutical, Technetium-99 m-labeled (99mTc) rituximab, for sentinel lymph node (SLN) detection.

METHODS

99mTc-rituximab was synthesized and tested for stability in human serum. The binding affinity to CD20 was evaluated in Raji cells by flow cytometric analysis. Biodistribution and sentinel node mapping were carried out in bal b/c mice. Eighty-five patients with breast cancer participated in this study. Dynamic sentinel lymphoscintigraphy was first assessed in 12 patients before planar lymphoscintigraphy was assessed in a larger cohort. All patients underwent sentinel lymph node biopsy (SLNB), followed by axillary lymph node dissection.

RESULTS

The cell-binding study showed that 99mTc-rituximab possessed compatible affinity to human CD20. In the mechanism study, 99mTc-labeled anti-mouse CD20 monoclonal antibodies could bind to mouse CD20 and accumulate in the SLN with 2.62±1.25 % of the percentage of injected activity, which could be blocked by excessive unlabeled antibody. Low uptake of non-sentinel nodes and fast clearance from the injection site were observed in the mice. Sentinel nodes were identified in 82 of 85 breast cancer patients (96.5%) by lymphoscintigraphy and SLNB. The sensitivity, specificity, and accuracy were 96.8% (30/31), 100% (51/51), and 98.8% (81/82), respectively.

CONCLUSION

99mTc-rituximab, specifically binding to CD20, met most of the requirements of an ideal sentinel mapping agent for use in clinical settings.

Lymphatic imaging: focus on imaging probes

In view of the importance of sentinel lymph nodes (SLNs) in tumor staging and patient management, sensitive and accurate imaging of SLNs has been intensively explored. Along with the advance of the imaging technology, various contrast agents have been developed for lymphatic imaging. In this review, the lymph node imaging agents were summarized into three groups: tumor targeting agents, lymphatic targeting agents and lymphatic mapping agents. Tumor targeting agents are used to detect metastatic tumor tissue within LNs, lymphatic targeting agents aim to visualize lymphatic vessels and lymphangionesis, while lymphatic mapping agents are mainly for SLN detection during surgery after local administration. Coupled with various signal emitters, these imaging agents work with single or multiple imaging modalities to provide a valuable way to evaluate the location and metastatic status of SLNs.