Comparison of [(99m)Tc]tilmanocept and filtered [(99m)Tc]sulfur colloid for identification of SLNs in breast cancer patients

A Four-Arm Randomized Clinical Trial of Topical Pain Control for Sentinel Node Radiotracer Injections in Patients with Breast Cancer

BACKGROUND

Radioactive tracer injections for breast cancer sentinel lymph node mapping can be painful. In this randomized trial, we compared four approaches to topical pain control for radiotracer injections.

METHODS

Breast cancer patients were randomized (9 April 2021-8 May 2022) to receive the institutional standard of ice prior to injection (n = 44), or one of three treatments: ice plus a vibrating distraction device (Buzzy®; n = 39), 4% lidocaine patch (n = 44), or 4% lidocaine patch plus ice plus Buzzy® (n = 40). Patients completed the Wong-Baker FACES® pain score (primary outcome) and a satisfaction with pain control received scale (secondary). Nuclear medicine technologists (n = 8) rated perceived pain control and ease of administration for each patient. At study conclusion, technologists rank-ordered treatments. Data were analyzed as intention-to-treat. Wilcoxon rank-sum tests were used to compare pain scores of control versus pooled treatment arms (primary) and then control to each treatment arm individually (secondary).

RESULTS

There were no differences in pain scores between the control and treatment groups, both pooled and individually. Eighty-five percent of patients were 'satisfied/very satisfied' with treatment received, with no differences between groups. No differences in providers' perceptions of pain were observed, although providers perceived treatments involving Buzzy© more difficult to administer (p < 0.001). Providers rated lidocaine patch as the easiest, with ice being second.

CONCLUSION

In this randomized trial, no differences in patient-reported pain or satisfaction with treatment was observed between ice and other topical treatments. Providers found treatments using Buzzy® more difficult to administer. Given patient satisfaction and ease of administration, ice is a reasonable standard.

Cost-Effectiveness of [99mTc]Tilmanocept Relative to [99mTc]Sulfur Colloid for Sentinel Lymph Node Biopsy in Early Stage Oral Cavity Cancer

BACKGROUND

Several studies have demonstrated varying rates of efficacy, reliability, and sensitivity of sentinel lymph node biopsy (SLNB) in identifying occult nodal disease for early stage oral cavity squamous cell carcinoma (OCSCC) depending on the radionuclide agent utilized. No head-to-head comparison of cost or clinical outcomes of SLNB when utilizing [99mTc]tilmanocept versus [99mTc]sulfur colloid has been performed. The goal of this study was to develop a decision model to compare the cost-effectiveness of [99mTc]tilmanocept versus [99mTc]sulfur colloid in early stage OCSCC.

PATIENTS AND METHODS

A decision model of disease and treatment as a function of SLNB was created. Patients with a negative SLNB entered a Markov model of the natural history of OCSCC parameterized with published data to simulate five states of health and iterated over a 30-year time horizon. Treatment costs and quality-adjusted life-years (QALYs) for each health state were included. The incremental cost-effectiveness ratio (ICER) was then estimated using $100,000 per additional QALY as the threshold for determining cost-effectiveness.

RESULTS

The base case cost-effectiveness analysis suggested [99mTc]tilmanocept was more effective than [99mTc]sulfur colloid by 0.12 QALYs (7.06 versus 6.94 QALYs). [99mTc]Tilmanocept was more costly, with a lifetime cost of $84,961 in comparison with $84,264 for sulfur colloid, however, the overall base case ICER was $5859 per additional QALY, well under the threshold for cost-effectiveness. Multiple one-way sensitivity analyses were performed, and demonstrated the model was robust to alternative parameter values.

CONCLUSION

Our analysis showed that while [99mTc]tilmanocept is more costly upfront, these costs are worth the additional QALYs gained by the use of [99mTc]tilmanocept.

99mTc-Tilmanocept performance for sentinel node mapping in breast cancer, melanoma, and head and neck cancer: a systematic review and meta-analysis from a European expert panel

PURPOSE

Although multiple radiopharmaceuticals are currently available for sentinel node (SN) biopsy, 99mTc-tilmanocept is of particular interest due to its low molecular weight and specific binding capability for the mannose receptors of lymphatic reticuloendothelial cells. In the current systematic review and meta-analysis, we aimed to provide an update from a European expert panel on the performance of 99mTc-tilmanocept for SN biopsy.

METHODS

A systematic literature search of the PubMed/Medline and Embase databases was performed to identify studies on the use of 99mTc-tilmanocept for SN identification in oncological patients. The articles' methodological quality was assessed before inclusion. The pooled estimates of the pre-/intraoperative detection rates (DR; proportion of patients with ≥ 1 SN identified) and/or pN + sensitivity (SN + /pN + patients ratio), with 95% confidence intervals (CIs), were calculated for breast cancer, melanoma, and head and neck cancer.

RESULTS

Twenty-four articles were included in the systematic review, and twenty-one provided data for the meta-analysis. According to data availability, the 99mTc-tilmanocept-estimated pooled preoperative and intraoperative DRs were 0.94 (95%CI, 0.88-1.01) and 0.99 (0.98-1.00) for breast cancer, 0.98 (0.96-0.99) and 1.00 (0.99-1.00) for melanoma, and 0.97 (0.93-1.02) and 0.99 (0.96-1.01) for head and neck carcinoma. Finally, the pooled sensitivity for nodal metastasis in melanoma was 0.97 (95% CI, 0.92-1.03).

CONCLUSION

99mTc-tilmanocept is a promising radiotracer for SN mapping in patients with breast cancer, melanoma, or head and neck cancer. We strongly believe that multicenter trials are still needed to assess if 99mTc-tilmanocept is superior to other radiotracers used in clinical routine.

Lymphoscintigraphy Using Tilmanocept Detects Multiple Sentinel Lymph Nodes in Melanoma Patients

BACKGROUND

Technetium-99m-labeled Tilmanocept, a multivalent mannose, is readily internalized by the CD206 surface receptor on macrophages and dendritic cells which are abundantly present in lymph nodes. We want to examine the drainage patterns of Technetium-99m-labeled Tilmanocept to sentinel lymph nodes (SLNs) in melanoma patients following the 10% rule.

METHODS

Multi-center retrospective review of patients with cutaneous melanoma undergoing SLN biopsy using Technetium-99m-labeled Tilmanocept between 2008 and 2014 was conducted. Statistical methods were used for data analyses.

RESULTS

Of the 564 patients (mean age of 60.3 and 62% male) with preoperative lymphoscintigraphy showing at least one SLN, several primary tumor sites were included: 27% head/neck, 33% trunk, 21% upper extremity and 19% lower extremity. For the head/neck primary site, 36.5% of patients had multiple draining basins; for the trunk site, 36.4% of patients; for the upper extremity site, 13% of patients; and for the lower extremity, 27.4% of patients. A median of 3 (range 1-18) SLNs were identified and resected. Overall, 78% of patients had >1 SLN identified by Technetium-99m-labeled Tilmanocept. In a multivariate model, patients with >1 SLN were significantly associated with age, Breslow depth, tumor location and higher AJCC tumor stage. A total of 17.7% of patients (100/564) had a positive SLN identified. A total of 145 positive SLNs were identified out of 1,812 SLNs with a positive SLN rate of 8%. Positive SLN status was significantly associated with younger age, greater Breslow depth, mitosis rate, higher AJCC tumor stage, presence of ulceration and angiolymphatic invasion.

CONCLUSIONS

Using the 10% rule, Technetium-99m-labeled Tilmanocept detects multiple SLNs in most melanoma patients.

Intraoperative diagnosis of «sentinel» lymph nodes in the patients with mammary gland cancer

Objective. To improve intraoperative determination of «sentinel» lymph nodes in patients, suffering mammary gland cancer. Materials and methods. In the 2016 – 2021 yrs period on the base of the Odessa Regional Clinical Hospital 200 patients, suffering mammary gland cancer Stages Т1–Т3N0М0, were operated, using two dyes: the blue patented dye and fluorescent dye indocyanine green. All the patients were distributed into two groups. In Group I in 100 patients the "sentinel" lymph nodes biopsy was conducted. The blue patented dye was used for the lymph nodes staining. The same was conducted in 100 patients of Group II with the "sentinel" lymph nodes biopsy. For the lymph nodes staining there were applied the blue patented dye and fluorescent dye indocyanine green, which were introduced intravenously into the upper extremity on the side of the affected mammary gland along outflow from the upper extremity to mammary gland. Results. General five–year survival after axillary lympho–dissection and after biopsy of «sentinel» lymph nodes have constituted 91 and 92%, accordingly, while recurrence–free five–year survival – 82.2 and 83.9% accordingly. Only in 1.1% patient a regional recurrence in «sentinel» lymph nodes on the affected mammary gland side was revealed. In 57% patients the unaffected «sentinel» lymph nodes were diagnosed, that's why further lympho–dissection was accomplished. In 43% women–patients there was revealed metastatic affection of the lymph nodes. Recurrence was registered in 0.2% patients as an isolated metastases in axillary lymph nodes. Conclusion. The method of the «sentinel» lymph nodes diagnosis in mammary gland cancer, using the dyes, permits to escape the performance of traumatic operations in favor of organ–preserving interventions with biopsy of «sentinel» lymph nodes.

Technetium Tc 99m tilmanocept fails to detect sentinel lymph nodes in endometrial cancer

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Indocyanine green (ICG) is effective for sentinel lymph node detection (SLN) in endometrial cancer.

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Technetium Tc 99m tilmanocept is FDA-approved for SLN detection in breast cancer, melanoma, and head and neck cancers.

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We aimed to determine the SLN detection rate in endometrial cancer with concurrent technetium Tc 99m tilmanocept and ICG use.

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Technetium Tc 99m tilmanocept failed to detect sentinel lymph nodes in endometrial cancer patients in our prospective study.

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ICG alone remains a standard SLN detection technique in endometrial cancer, while limiting burdens from a dual agent.

Background

Technetium Tc 99m tilmanocept is a synthetic radiotracer specifically designed for sentinel lymph node (SLN) mapping that has been FDA-approved in breast cancer, melanoma, and head and neck cancer. No published studies exist for the use of this radiotracer in endometrial cancer.

Objective

The primary objective was to determine the detection rate of bilateral SLNs in endometrial cancer with the concurrent use of technetium Tc 99m tilmanocept and ICG.

Methods

An open-label, single cohort, prospective feasibility study was conducted with participants receiving preoperative cervical injections of technetium Tc 99m tilmanocept followed by subsequent imaging and SPECT/CT. Intraoperative ICG injections were administered for all patients with near-infrared imaging used to visualize lymphatic vessels and nodes. A laparoscopic gamma counter was used to detect radioactive SLN intraoperatively.

Results

All six evaluated patients had FIGO grade 1 or 2 endometrioid histology. Stage IA/IB were in 33% and 66% of patients, respectively. Tilmanocept did not map any SLN in the first six patients but instead showed retention of the tracer in the cervical stroma, leading to study discontinuation for futility. ICG mapped bilateral SLN in all patients with the most common location being the external iliac region, followed by the obturator and common iliac areas. All patients had CD206 positive staining throughout the full wall thickness of ectocervix, transformation zone, endocervix, and lymphatic vessels. No patients experienced adverse events.

Conclusion

Technetium Tc 99m tilmanocept did not detect SLN in early stage endometrial cancers and is unlikely to improve bilateral detection rate compared to ICG alone. ICG remains a standard technique for SLN detection in low stage, low grade endometrial cancer.

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.

The Use and Technique of Sentinel Node Biopsy for Skin Cancer

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the indications for and prognostic value of sentinel lymph node biopsy in skin cancer. 2. Learn the advantages and disadvantages of various modalities used alone or in combination when performing sentinel lymph node biopsy. 3. Understand how to perform sentinel lymph node biopsy in skin cancer patients.

SUMMARY

Advances in technique used to perform sentinel lymph node biopsy to assess lymph node status have led to increased accuracy of the procedure and improved patient outcomes.

Value of Quantitative SPECT/CT Lymphoscintigraphy in Improving Sentinel Lymph Node Biopsy in Breast Cancer

Methods

We retrospectively enrolled breast cancer patients who underwent SPECT/CT prior to sentinel lymph node biopsy. Quantification of radiotracer uptake from SPECT/CT data was performed. A radioactivity count threshold (R_SPECT) using SPECT/CT was calculated for detecting metastatic sentinel lymph nodes. To localize sentinel lymph nodes exactly, we compared the positions of sentinel lymph nodes localized using SPECT/CT with positions localized surgically using an intraoperative γ-probe.

Results

491 patients were included, with a median of 3 sentinel lymph nodes/patient detected by the γ-probe and 2 sentinel lymph nodes/patient detected by SPECT/CT. As the number of sentinel lymph nodes visualized on SPECT/CT images, the metastasis incidence of lymph nodes in the ≤2 SLNs group was significantly higher than that in the >2 SLNs group (35% vs. 15%, P < 0.001). No metastasis was found in lymph nodes with R_SPECT ≤ 30% in the >2 SLNs group, and thus, 30% (157/526) of SPECT/CT-identified nodes would avoid unnecessary removal. The positions of sentinel lymph nodes localized by SPECT/CT and γ-probe were identical in 42% (39/93) of patients.

Conclusions

Quantitative Tc-99 m SC SPECT/CT imaging has the potential to preoperatively locate sentinel lymph nodes and intraoperatively avoid unnecessary sentinel lymph node biopsy.

How much time is enough? Sentinel lymph node mapping time depends on the radiotracer agent

BACKGROUND

In 2014, technetium-99m tilmanocept (TcTM) replaced technetium-99m sulfur colloid (TcSC) as the standard lymphoscintigraphy (LS) mapping agent in melanoma patients undergoing sentinel lymph node biopsy (SLNB). The aim of this study was to examine differences in mapping time, intra-operative identification of sentinel lymph node (SLN), and false negative rate (FNR) between patients who underwent SLNB with TcTM compared to TcSC.

METHODS

Patients who underwent SLNB between 2010 and 2018 were retrospectively identified. Patient demographic, tumor, and imaging data was stratified by receipt of TcSC (n = 258) or TcTM (n = 133). Student's t test and χ² test were used to compare characteristics and outcomes.

RESULTS

Both cohorts were similar in demographic, primary tumor characteristics, and total number of SLN identified (TcTM 3.56 vs. TcSC 3.28, p = 0.244). TcTM was associated with significantly shorter LS mapping times (51.8 vs. 195.1 min, p < 0.01). There was no significant difference in the number of patients with positive SLN (TcTM 11.3 vs. TcSC 17.4%, p = 0.109) and the FNR was similar between both groups (TcTM 25% vs. TcSC 22%).

CONCLUSION

TcTM was associated with significantly shorter LS mapping time while identifying similar numbers of SLN. Our results support further study to ensure similar FNR and oncologic outcomes between agents.

Sentinel Lymph Node Biopsy in Breast Cancer with 99mTc-Tilmanocept: A Multicenter Study on Real-Life Use of a Novel Tracer

^99mTc-tilmanocept is a novel radiopharmaceutical for sentinel lymph node (SLN) biopsy in breast cancer. Our aim was to describe results with ^99mTc-tilmanocept in a heterogeneous group of breast cancer patients scheduled for SLN biopsy. Methods: Radiotracer preparation followed the manufacturer's indications. Local protocols for SLN detection within 9 participant centers were not changed for the entire duration of the study. In total, 344 patients with T1-T4, N0-N2 breast cancer (352 lesions) were included. Superficial (intradermal or periareolar) or deep (peritumoral or intratumoral) injections were performed. The doses were adjusted depending on the scheduled time for surgery. Results: Lymphoscintigraphy was able to depict at least 1 SLN in 339 of 352 breast lesions (96.3%), and the intraoperative SLN detection rate reached 97.2%. On univariable analysis, SLN detection rates did not differ by age, clinical T or N stage, tumor location, histologic subtype, or prior neoadjuvant therapy. Lymphoscintigraphy showed higher SLN detection in patients with a normal weight (body mass index < 25) than in those who were overweight or obese (body mass index ≥ 25), at 99.2% versus 94.6%, respectively (P = 0.031). The proportion of patients with preoperative lymphoscintigraphic detection or excised SLNs was higher with superficial than deep injections. Reinjected cases were significantly lower when superficial injection was chosen first (P < 0.001). Injection site and the tumor markers human epidermal growth factor receptor 2 and estrogen receptor had an impact on preoperative SLN visualization and intraoperative localization. In 80 cases, SLN biopsy resulted in a positive lymph node. During a mean follow-up of 19 mo, no axillary recurrences were observed. Conclusion: Whatever the protocol, ^99mTc-tilmanocept showed good results in a heterogeneous breast cancer population, although the best results were achieved when a superficial injection was chosen.

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.

Interventional nuclear medicine: a focus on radioguided intervention and surgery

Within interventional nuclear medicine (iNM) a prominent role is allocated for the sub-discipline of radioguided surgery. Unique for this discipline is the fact that an increasing number of clinical indications (e.g. lymphatic mapping, local tumor demarcation and/or tumor receptor targeted applications) have been adopted into routine care. The clinical integration is further strengthened by technical innovations in chemistry and engineering that enhance the translational potential of radioguided procedures in iNM. Together, these features not only ensure ongoing expansion of iNM but also warrant a lasting clinical impact for the sub-discipline of radioguided surgery.

Optimal efficient imaging time for identification of sentinel lymph node with Tc-99m Tilmanocept in breast cancer patients

We determined the optimal imaging time for axillary lymph node (LN) visualization following Tc-99m Tilmanocept in breast cancer patients to establish imaging guidelines that can allow for a reliable and efficient yet high yield study prior to surgery. Retrospective analysis in 651 patients who underwent lymphoscintigraphy, comparing LN visualization on immediate, 15-minute, and 90-minute delayed imaging after injection of Tc-99m Tilmanocept. Statistical analysis was performed using McNemar's test, kappa coefficient, and Pearson Chi-square test. Five hundred and six patients had either immediate or immediate and 90-minute delayed imaging. Of these patients, 203 (40.1%) had both immediate and 90-minute delayed images. Of these 203 patients, 54 (26.6%) had ≥1 lymph node(s) identified immediately and 196 (96.6%) had ≥1 lymph node(s) identified at 90 minutes (P<0.0001). A kappa coefficient of .0256 was observed (95% CI: .0058-.0453). One hundred and forty-five additional patients had 15-minute delayed imaging. Of these patients, 117 (80.7%) had ≥1 lymph node(s) identified, which was significantly fewer compared to the number of patients with ≥1 lymph node(s) detected at 90 minutes (P<0.0001). Ninety-minute delayed imaging is optimal for identifying sentinel lymph node(s) following Tc-99m Tilmanocept injection in breast cancer patients.

Positron Lymphography via Intracervical 18F-FDG Injection for Presurgical Lymphatic Mapping in Cervical and Endometrial Malignancies

The presence of metastasis in local lymph nodes (LNs) is a key factor influencing choice of therapy and prognosis in cervical and endometrial cancers; therefore, the exploration of sentinel LNs (SLNs) is highly important. Currently, however, SLN mapping requires LN biopsy for pathologic evaluation, since there are no clinical imaging approaches that can identify tumor-positive LNs in early stages. Staging lymphadenectomy poses risks, such as leg lymphedema or lymphocyst formation. Furthermore, in 80%-90% of patients, the explored LNs are ultimately tumor-free, meaning most patients are unnecessarily subjected to lymphadenectomy. Methods: Current lymphoscintigraphy methods identify only the anatomic location of the SLNs and do not provide information on their tumor status. There are no noninvasive methods to reliably identify metastases in LNs before surgery. We have developed positron lymphography (PLG), a method to detect tumor-positive LNs, in which ¹⁸F-FDG is injected interstitially into the uterine cervix on the day of surgery, and its rapid transport through the lymphatic vessels to the SLN is then visualized with dynamic PET/CT. We previously showed that PLG was able to identify metastatic LNs in animal models. Here, we present the first results from our pilot clinical trial (clinical trials identifier NCT02285192) in 23 patients with uterine or cervical cancer. On the morning of surgery, ¹⁸F-FDG was injected into the cervix, followed by an immediate dynamic PET/CT scan of the pelvis and a delayed 1-h whole-body scan. Results: There were 3 (15%) node-positive cases on final pathologic analysis, and all of these LNs (including 1 with a focus of only 80 tumor cells) were identified by PLG. There were 2 (10%) false-positive cases with PLG, in which the final pathology of the corresponding SLNs was negative for tumor. Conclusion: This first-in-humans study of PLG in women with uterine and cervical cancer demonstrates its feasibility and its ability to identify patients with nodal metastases and warrants further evaluation in additional studies.

Single Photon Emission Computed Tomography Tracer

Single photon emission computed tomography (SPECT) is the state-of-the-art imaging modality in nuclear medicine despite the fact that only a few new SPECT tracers have become available in the past 20 years. Critical for the future success of SPECT is the design of new and specific tracers for the detection, localization, and staging of a disease and for monitoring therapy. The utility of SPECT imaging to address oncologic questions is dependent on radiotracers that ideally exhibit excellent tissue penetration, high affinity to the tumor-associated target structure, specific uptake and retention in the malignant lesions, and rapid clearance from non-targeted tissues and organs. In general, a target-specific SPECT radiopharmaceutical can be divided into two main parts: a targeting biomolecule (e.g., peptide, antibody fragment) and a γ-radiation-emitting radionuclide (e.g., ^99mTc, ¹²³I). If radiometals are used as the radiation source, a bifunctional chelator is needed to link the radioisotope to the targeting entity. In a rational SPECT tracer design, these single components have to be critically evaluated in order to achieve a balance among the demands for adequate target binding, and a rapid clearance of the radiotracer. The focus of this chapter is to depict recent developments of tumor-targeted SPECT radiotracers for imaging of cancer diseases. Possibilities for optimization of tracer design and potential causes for design failure are discussed and highlighted with selected examples.

Detection of lymph node metastasis with near-infrared upconversion luminescent nanoprobes

The detection of lymph node metastasis is of great importance for therapy planning and prognosis of cancers, but remains challenging in the clinic. In the current study, we report a tumor-specific imaging probe constructed with NaGdF4:Yb,Tm,Ca@NaLuF4 core@shell upconversion nanoparticles showing distinctive near infrared emission. The following studies revealed that the characteristic Tm dopant emission at 804 nm showed a penetration depth up to 7.7 mm through multi-layered mice skin tissues, substantially greater than emissions at 655 nm and 541 nm typically from the widely used Er dopant, which is apparently favorable for sensitive tumor diagnosis. The cell binding assay further revealed that the anti-HER2 antibodies covalently attached on the particle surface endowed the nanoprobe with excellent binding specificity in targeting HER2-positive cancer cells in vitro, which further enabled the detection of lymph node metastasis of breast cancer in vivo in mice. In addition, the pharmacokinetics of the resulting nanoprobes were intensively studied through both upconversion luminescence imaging and SPECT imaging for comparing with that of the mother particles. The results obtained through both approaches were well consistent and revealed that the surface conjugation of antibodies largely altered the pharmacokinetic behaviors and substantially prolonged the blood half-life of the underlying nanoparticles, which was never reported before.

Next generation of radiotracers for sentinel lymph node biopsy: What is still necessary to establish new imaging paradigms?

Sentinel lymph node (SLN) biopsy is now the standard of care for regional staging in several solid tumors. The interstitial administration of a radiotracer around the primary tumor provide the possibility to sequentially obtain images with a gamma camera and visualize lymphatic mapping and the SLN. There is, however, a large geographical variability in those radiotracers and nanocolloids ranging from 15-100nm which are most widely employed in Europe, while filtered and unfiltered ^99mTc-sulfur colloid (range 20-1000nm) is usually used in the USA with different drawbacks in its use. The new radiotracer ^99mTc-Tilmanocept, designed specifically for the identification of SLNs and recently becoming commercially available in USA and Europe, appears to have the potency to overcome the shortcomings described for the conventional radiotracers used until now for SLN biopsy and at the same time to transform current imaging paradigms. After delineating the challenges for the next generation of radiotracers, this paper discusses the properties of ^99mTc-Tilmanocept, its validation process for SLN biopsy and its emerging clinical applications in various malignancies.

Consecutive Case Series of Melanoma Sentinel Node Biopsy for Lymphoseek Compared to Sulfur Colloids

BACKGROUND

Sentinel lymph node biopsy (SLNB) is an important adjunct in the staging of patients with melanoma. Preoperative lymphoscintigraphy with radiolabeled isotopes is essential to localize sentinel nodes for removal. Our study compared the effectiveness of Lymphoseek to standard sulfur colloids in patients with melanoma undergoing SLNB.

METHODS

We queried our IRB-approved melanoma database to identify 370 consecutive patients who underwent SLNB from 2012 to 2016 with at least 1 y of follow-up. There were 185 patients in each group. Data points included characteristics of the primary melanoma lymphoscintigraphy and SLNB. Student's t-test and chi-square were used to analyze the data with a P value of <0.05 being considered significant.

RESULTS

Patients were equally matched in regard to age, sex, and primary characteristics of their melanoma. In comparison to sulfur colloid, Lymphoseek required lower radiation dosages (P < 0.001), shorter mapping times (P = 0.008), and decreased number of sentinel nodes removed (P = 0.03). There was no difference in the number of patients with positive nodes (P = 0.5). In addition, there were no statistical differences between the two radioactive tracers in regard to the number of patients with false-negative SLNB.

CONCLUSION

Lymphoseek has the potential to decrease radioactivity and mapping time in patients who need SLNB. With a decrease in the number of nodes removed without loss of sensitivity, there is a potential to avoid unnecessary node removal and thus complications such as lymphedema. Longer follow-up will help to determine if there is any increase in false-negative rates despite fewer nodes removed.

Outcomes of "one-day" vs "two-day" injection protocols using Tc-99m tilmanocept for sentinel lymph node biopsy in breast cancer

No prior studies have compared Tc-99m tilmanocept (TcTM) one-day and two-day injection protocols for sentinel lymph node (SLN) biopsy in breast cancer (BC). We retrospectively identified patients with clinically node-negative BC undergoing SLN biopsy at our institution. Patients received a single, intradermal peritumoral injection of TcTM on day of surgery or day prior to surgery in addition to an intraoperative injection of isosulfan blue dye. Univariable and multivariable Poisson regression count models were constructed to assess the effects of injection timing, radiologist, patient and surgeon characteristics on the number of removed SLNs. A total of 617 patients underwent SLN biopsy with TcTM and blue dye. Sixty-seven (10.9%) patients were injected with the two-day protocol. Patients in the one-day protocol had a mean of 3.0 (standard deviation (SD) 1.9) SLNs removed compared with 2.7 (SD 1.4) SLNs in the two-day protocol, P-value = .13. On multivariable analysis, patient age and operating surgeon significantly affected the number of removed SLNs; however, the injection timing and the nuclear radiologist did not influence the number of removed SLNs. The performance of Tc-99m tilmanocept did not differ significantly between one-day and two-day injection protocols. These results are similar to other radiotracers used for SLN biopsy in BC.

Dual-Modal Probe Based on Polythiophene Derivative for Pre- and Intraoperative Mapping of Lymph Nodes by SPECT/Optical Imaging

The metastatic spread of primary tumors to regional lymph nodes (LNs) is an important prognostic indicator for cancer staging and clinical therapy. Therefore, developing lymphatic mapping probes with improved accuracy and efficiency is of vital importance. Conjugated polymers (CPs) have been established as useful optical probes for sensitive biological and chemical detection. As a member of CPs family, polythiophene derivatives have drawn increasing attraction because of their superior photostability, signal amplification ability, and flexible structures for modification. In addition, these excellent properties allow the promising in vivo application to real-time LNs mapping. Here, we first reported a radiolabeled dual-modal probe based on the polythiophene derivative (^99mTc-PTP) that was used for LNs mapping with high sensitivity and specificity by preoperative single-photon emission computed tomography imaging and intraoperative optical guidance. ^99mTc-PTP exhibits an excellent radio-fluorescence guidance ability and a remarkable biocompatibility and holds great potential to be a powerful probe for noninvasive LNs mapping.

Desirable Properties of Radiopharmaceuticals for Sentinel Node Mapping in Patients With Breast Cancer Given the Paradigm Shift in Patient Management

Over the past 2 decades, lymphoscintigraphy and sentinel node biopsy have become widely accepted and are used by surgeons to stage many solid cancers, especially breast cancer. However, despite growing experience, there are a number of unresolved issues. In addition, the impact of a new radiopharmaceutical remains to be determined. The present article addresses some of these issues (either unresolved, recurrent, or newly emerged), with a focus on the properties of radiopharmaceuticals used for sentinel node mapping in breast cancer.

Lymphoscintigraphy detecting alterations of upper limb lymphatic flow following early sentinel lymph node biopsy in breast cancer

Purpose

To evaluate early variations in lymphatic circulation of the arm pre- and post-sentinel lymph node biopsy (SLNB) and conservative breast surgery by lymphoscintigraphy (LS).

Patients and methods

Between 2005 and 2012, 15 patients underwent LS before and after the SLNB (total=30 studies). The pre-SLNB study was considered the control. Early images within twenty minutes (dynamic and static images) and delayed images within ninety minutes of arms and armpits were acquired using a gamma camera. The LS images before and after the SLNB of each patient were paired and compared to each other, evaluating the site of lymphatic flow (in the early phase) and identifying the number of lymph nodes (in the late phase). These dynamic images were subjected to additional quantitative analysis to assess the lymphatic flow rate using the slope assessed by the angular coefficient of the radioactivity × time curves in areas of interest recorded in the axillary region. The variations of lymphatic flow and the number of lymph nodes in the post-SLNB LS compared to the pre-SLNB LS of each patient were classified as decreased, sustained or increased. The clinical variables analyzed included the period between performing the SLNB and the subsequent LS imaging, age, body mass index, number of removed lymph nodes, type of surgery and whether immediate oncoplastic surgery was performed.

Results

The mean age was 54.53±9.03 years (36–73 years), the mean BMI was 27.16±4.16 kg/m² (19.3–34.42), and the mean number of lymph nodes removed from each patient was 1.6±0.74 (1–3). There was significant difference in the time between surgery and the realization of LS (p=0.002; Mann–Whitney U test), but in an inverse relationship, the higher was the range, the smaller was the lymphatic flow, indicating a gradual reduction of lymphatic flow after surgery (Spearman’s p=0.498, with p=0.013).

Conclusion

Upper limb lymphatic flow gradually decreased after the SLNB and conservative breast surgery in this study, but these results are exploratory because of the small sample size. Further studies are needed to confirm and to investigate more in depth these findings.

The role of ultrasound and lymphoscintigraphy in the assessment of axillary lymph nodes in patients with breast cancer

Breast cancer is the most common malignancy and the leading cause of death due to cancer in European women. Mammography screening programs aimed to increase the detection of early cancer stages were implemented in numerous European countries. Recent data show a decrease in mortality due to breast cancer in many countries, particularly among young women. At the same time, the number of sentinel node biopsy procedures and breast-conserving surgeries has increased. Intraoperative sentinel lymph node biopsy preceded by lymphoscintigraphy is used in breast cancer patients with no clinical signs of lymph node metastasis. Due to the limited sensitivity and specificity of physical examination in detecting metastatic lesions, developing an appropriate diagnostic algorithm for the preoperative assessment of axillary lymph nodes seems to be a challenge. The importance of ultrasound in patient qualification for sentinel lymph-node biopsy has been discussed in a number of works. Furthermore, different lymphoscintigraphy protocols have been compared in the literature. The usefulness of novel radiopharmaceuticals as well as the methods of image acquisition in sentinel lymph node diagnostics have also been assessed. The aim of this article is to present, basing on current guidelines, literature data as well as our own experience, the diagnostic possibilities of axillary lymph node ultrasound in patient qualification for an appropriate treatment as well as the role of lymphoscintigraphy in sentinel lymph node biopsy.

The inextricable axis of targeted diagnostic imaging and therapy: An immunological natural history approach

In considering the challenges of approaches to clinical imaging, we are faced with choices that sometimes are impacted by rather dogmatic notions about what is a better or worse technology to achieve the most useful diagnostic image for the patient. For example, is PET or SPECT most useful in imaging any particular disease dissemination? The dictatorial approach would be to choose PET, all other matters being equal. But is such a totalitarian attitude toward imaging selection still valid? In the face of new receptor targeted SPECT agents one must consider the remarkable specificity and sensitivity of these agents. (99m)Tc-Tilmanocept is one of the newest of these agents, now approved for guiding sentinel node biopsy (SLNB) in several solid tumors. Tilmanocept has a Kd of 3×10(-11)M, and it specificity for the CD206 receptor is unlike any other agent to date. This coupled with a number of facts, that specific disease-associated macrophages express this receptor (100 to 150 thousand receptors), that the receptor has multiple binding sites for tilmanocept (>2 sites per receptor) and that these receptors are recycled every 15 min to bind more tilmanocept (acting as intracellular "drug compilers" of tilmanocept into non-degraded vesicles), gives serious pause as to how we select our approaches to diagnostic imaging. Clinically, the size of SLNs varies greatly, some, anatomically, below the machine resolution of SPECT. Yet, with tilmanocept targeting, the SLNs are highly visible with macrophages stably accruing adequate (99m)Tc-tilmanocept counting statistics, as high target-to-background ratios can compensate for spatial resolution blurring. Importantly, it may be targeted imaging agents per se, again such as tilmanocept, which may significantly shrink any perceived chasm between the imaging technologies and anchor the diagnostic considerations in the targeting and specificity of the agent rather than any lingering dogma about the hardware as the basis for imaging approaches. Beyond the elements of imaging applications of these agents is their evolution to therapeutic agents as well, and even in the neo-logical realm of theranostics. Characteristics of agents such as tilmanocept that exploit the natural history of diseases with remarkably high specificity are the expectations for the future of patient- and disease-centered diagnosis and therapy.

Comparison of Post-injection Site Pain Between Technetium Sulfur Colloid and Technetium Tilmanocept in Breast Cancer Patients Undergoing Sentinel Lymph Node Biopsy

BACKGROUND

No prior studies have examined injection pain associated with Technetium-99m Tilmanocept (TcTM).

METHODS

This was a randomized, double-blinded study comparing postinjection site pain between filtered Technetium Sulfur Colloid (fTcSC) and TcTM in breast cancer lymphoscintigraphy. Pain was evaluated with a visual analogue scale (VAS) (0-100 mm) and the short-form McGill Pain Questionnaire (SF-MPQ). The primary endpoint was mean difference in VAS scores at 1-min postinjection between fTcSC and TcTM. Secondary endpoints included a comparison of SF-MPQ scores between the groups at 5 min postinjection and construction of a linear mixed effects model to evaluate the changes in pain during the 5-min postinjection period.

RESULTS

Fifty-two patients underwent injection (27-fTcSC, 25-TcTM). At 1-min postinjection, patients who received fTcSC experienced a mean change in pain of 16.8 mm (standard deviation (SD) 19.5) compared with 0.2 mm (SD 7.3) in TcTM (p = 0.0002). At 5 min postinjection, the mean total score on the SF-MPQ was 2.8 (SD 3.0) for fTcSC versus 2.1 (SD 2.5) for TcTM (p = 0.36). In the mixed effects model, injection agent (p < 0.001), time (p < 0.001) and their interaction (p < 0.001) were associated with change in pain during the 5-min postinjection period. The model found fTcSC resulted in significantly more pain of 15.2 mm (p < 0.001), 11.3 mm (p = 0.001), and 7.5 mm (p = 0.013) at 1, 2, and 3 min postinjection, respectively.

CONCLUSIONS

Injection with fTcSC causes significantly more pain during the first 3 min postinjection compared with TcTM in women undergoing lymphoscintigraphy for breast cancer.

Sentinel Lymph Node Mapping of Liver

BACKGROUND

Although the sentinel lymph node (SLN) hypothesis has been applied to many tissues and organs, liver has remained unstudied. Currently, it is unclear whether hepatic SLNs even exist. If so, they could alter the management of intrahepatic cholangiocarcinoma and other hepatic malignancies by minimizing the extent of surgery while still providing precise nodal staging. This study investigated whether invisible yet tissue-penetrating near-infrared (NIR) fluorescent light can provide simultaneous identification of both the SLN and all other regional lymph nodes (RLNs) in the liver.

METHODS

In 25 Yorkshire pigs, this study determined whether SLNs exist in liver and compared the effectiveness of two clinically available NIR fluorophores [methylene blue and indocyanine green (ICG)], and two novel NIR fluorophores previously described by our group (ESNF14 and ZW800-3C) for SLN and RLN mapping.

RESULTS

In this study, ESNF14 showed the highest signal-to-background ratio and the longest retention time in SLNs without leakage to second-tier lymph nodes. The findings showed that ICG had apparent leakage to second-tier nodes, and ZW800-3C had poor migration after intraparenchymal injection. However, when injected intravenously, ZW800-3C was able to highlight all RLNs in liver during a 4- to 6-h period. Simultaneous dual-channel imaging of SLN (ESNF14) and RLN (ZW800-3C) permitted unambiguous identification and image-guided resection of SLNs and RLNs in liver.

CONCLUSION

The NIR imaging technology enables real-time intraoperative identification of SLNs and RLNs in the liver of swine. If these results are confirmed in patients, new strategies for the surgical management of intrahepatic malignancies should be possible.