Microsurgery guided by sequential preoperative lymphography using 68Ga-NEB PET and MRI in patients with lower-limb lymphedema

Imaging of the Lymphatic Vessels for Surgical Planning: A Systematic Review

BACKGROUND

Secondary lymphedema is a common complication after surgical or radiotherapeutic cancer treatment. (Micro) surgical intervention such as lymphovenous bypass and vascularized lymph node transfer is a possible solution in patients who are refractory to conventional treatment. Adequate imaging is needed to identify functional lymphatic vessels and nearby veins for surgical planning.

METHODS

A systematic literature search of the Embase, MEDLINE ALL via Ovid, Web of Science Core Collection and Cochrane CENTRAL Register of Trials databases was conducted in February 2022. Studies reporting on lymphatic vessel detection in healthy subjects or secondary lymphedema of the limbs or head and neck were analyzed.

RESULTS

Overall, 129 lymphatic vessel imaging studies were included, and six imaging modalities were identified. The aim of the studies was diagnosis, severity staging, and/or surgical planning.

CONCLUSION

Due to its utility in surgical planning, near-infrared fluorescence lymphangiography (NIRF-L) has gained prominence in recent years relative to lymphoscintigraphy, the current gold standard for diagnosis and severity staging. Magnetic resonance lymphography (MRL) gives three-dimensional detailed information on the location of both lymphatic vessels and veins and the extent of fat hypertrophy; however, MRL is less practical for routine presurgical implementation due to its limited availability and high cost. High frequency ultrasound imaging can provide high resolution imaging of lymphatic vessels but is highly operator-dependent and accurate identification of lymphatic vessels is difficult. Finally, photoacoustic imaging (PAI) is a novel technique for visualization of functional lymphatic vessels and veins. More evidence is needed to evaluate the utility of PAI in surgical planning.

Visual analysis of global research output of lymphedema based on bibliometrics

Background

Globally, several generations of doctors in the field of lymphedema have created numerous publications. To date, no bibliometric analysis has been performed specifically on these publications. For the further promotion of research on lymphedema and to align with the international research frontiers, it is essential to understand the current state of Lymphedema research output.

Objective

This study aims to statistically and visually analyze the characteristics of publications output, distribution of contributions and development process of lymphedema, enriching the knowledge base of Lymphedema, and then seek potential research topics and collaborators.

Methods

Based on the Web of Science core collection database, we firstly analyzed the quantity and quality of publications in the field of lymphedema, secondly profiled the publishing groups in terms of country, institution, author's publication and cooperation network, and finally sorted out and summarized the hot topics of research.

Results

A total of 8569 papers were retrieved from 1900-2021. The top4 journals with the most publications were LYMPHOLOGY, LYMPHATIC RESEARCH AND BIOLOGY, PLASTIC AND RECONSTRUCTIVE SURGERY and ANNALS OF SURGICAL ONCOLOGY. The top 4 countries with the most publications were USA, Japan, UK, and China. The United States dominates the total number of publications and the international cooperation network. The most productive research institution is Harvard University, and the research institution with the most collaborating institutions is Memorial Sloan Kettering Cancer Center. Mortimer, Peter S contributes the most research in this field. The research achievements of Japanese scholars in this field are of great significance. The top 5 ranked keywords are "Breast Cancer", "Health-Related Quality Of Life", "Lymphscintigraphy", "Lymphovenous Anastomosis", and "Lymphangiogenesis".

Conclusion

More and more scholars are devoted to the research of cancer-related Lymphedema. It is foreseeable that breast cancer-related lymphedema and lymphangiogenesis will remain a focus of future research. Advances in Lymphatic vessel imaging and the development of lymphatic microsurgery will further play a role in the clinical workup of lymphedema. Meanwhile, This study can help researchers identify potential collaborators and partner institutions and contribute to further research.

The bright future of nanotechnology in lymphatic system imaging and imaging-guided surgery

Lymphatic system is identified the second vascular system after the blood circulation in mammalian species, however the research on lymphatic system has long been hampered by the lack of comprehensive imaging modality. Nanomaterials have shown the potential to enhance the quality of lymphatic imaging due to the unparalleled advantages such as the specific passive targeting and efficient co-delivery of cocktail to peripheral lymphatic system, ease molecular engineering for precise active targeting and prolonged retention in the lymphatic system of interest. Multimodal lymphatic imaging based on nanotechnology provides a complementary means to understand the kinetics of lymphoid tissues and quantify its function. In this review, we introduce the established approaches of lymphatic imaging used in clinic and summarize their strengths and weaknesses, and list the critical influence factors on lymphatic imaging. Meanwhile, the recent developments in the field of pre-clinical lymphatic imaging are discussed to shed new lights on the design of new imaging agents, the improvement of delivery methods and imaging-guided surgery strategies.

Sentinel lymph node detection by combining nonradioactive techniques with contrast agents: State of the art and prospects

The status of sentinel lymph nodes (SLNs) has a substantial prognostic value because these nodes are the first place where cancer cells accumulate along their spreading route. Routine SLN biopsy ("gold standard") involves peritumoral injections of radiopharmaceuticals, such as technetium-99m, which has obvious disadvantages. This review examines the methods used as "gold standard" analogs to diagnose SLNs. Nonradioactive preoperative and intraoperative methods of SLN detection are analyzed. Promising photonic tools for SLNs detection are reviewed, including NIR-I/NIR-II fluorescence imaging, photoswitching dyes for SLN detection, in vivo photoacoustic detection, imaging and biopsy of SLNs. Also are discussed methods of SLN detection by magnetic resonance imaging, ultrasonic imaging systems including as combined with photoacoustic imaging, and methods based on the magnetometer-aided detection of superparamagnetic nanoparticles. The advantages and disadvantages of nonradioactive SLN-detection methods are shown. The review concludes with prospects for the use of conservative diagnostic methods in combination with photonic tools.

The relationship between the drainage function of inguinal lymph nodes and unilateral pelvic cancer-related lymphedema: A retrospective analysis

The aim of this study was to investigate the relationship between iliolumbar lymph nodes (LNs), inguinal LNs, and unilateral pelvic cancer-related lymphedema by retrospective analysis of lymphoscintigraphy data.Ninety-six patients (3 men and 93 women; mean age, 53.3 ± 11.3 years) with pelvic cancer-related lymphedema were enrolled in this retrospective study. Lymphoscintigraphy was performed at 1 hour and 4 to 6 hours after injection. The visualization of inguinal LNs and iliolumbar LNs were recorded.According to statistical analysis, the display of inguinal LNs in lymphoscintigraphy has a significant negative correlation with ipsilateral lower limb lymphedema (P < .01, r = -0.561). However, there is no correlation between the show of iliolumbar LNs and ipsilateral lower extremity lymphedema (P = .056, r = -0.138). When lymphoscintigraphy was performed at 1 hour after injection, there were 13 out of 96 patients without inguinal LNs revealed on imaging, but at 4 to 6 hours after injection, inguinal LNs were seen in lymphoscintigraphy.The drainage function of inguinal LNs has a significant negative correlation with ipsilateral pelvic cancer-related lymphedema. Treatment dedicated to restoring the drainage function of LNs in the inguinal region may effectively relieve lymphedema. The image acquisition at 4 to 6 hours after injection is necessary for significant additional information.

Innovations in lymph node targeting nanocarriers

Lymph nodes are secondary lymphoid tissues in the body that facilitate the co-mingling of immune cells to enable and regulate the adaptive immune response. They are also tissues implicated in a variety of diseases, including but not limited to malignancy. The ability to access lymph nodes is thus attractive for a variety of therapeutic and diagnostic applications. As nanotechnologies are now well established for their potential in translational biomedical applications, their high relevance to applications that involve lymph nodes is highlighted. Herein, established paradigms of nanocarrier design to enable delivery to lymph nodes are discussed, considering the unique lymph node tissue structure as well as lymphatic system physiology. The influence of delivery mechanism on how nanocarrier systems distribute to different compartments and cells that reside within lymph nodes is also elaborated. Finally, current advanced nanoparticle technologies that have been developed to enable lymph node delivery are discussed.

Visualization of Both the Superficial and Deep Lymphatic System of the Upper Extremity Using Magnetic Resonance Lymphography

Background: The lymphatic system consists of the superficial and deep lymphatic system. Several diagnostic methods are used to assess the lymphatic system. Lymphoscintigraphy and indocyanine green lymphography are widely applied, both showing disadvantages, such as a poor resolution and lack of field of view. Magnetic resonance lymphography (MRL) shows satisfactory temporal and spatial resolution. The aim of this study was to assess both the superficial and deep lymphatic system in the upper extremity of healthy subjects, using an MRL protocol. Methods and Results: Ten healthy volunteers underwent an MRL examination, using a three Tesla MRI unit. Water-soluble gadolinium was used as a contrast agent. MRL images were evaluated by an experienced radiologist on image quality, enhancement of veins and lymphatic vessels, and characteristics of the latter. Overall image quality was good to excellent. In all subjects, veins and lymphatic vessels could be distinguished. Superficial and deep lymphatic vessels were seen in 9 out of 10 subjects. Lymphatic vessels with a diameter between 0.9 and 4.3 mm were measured. Both veins and lymphatic vessels showed their characteristic appearance. Enhancement of veins was seen directly after contrast agent injection, which decreased over time. Lymphatic vessel enhancement slowly increased over time. Mean total MRL examination (room) time was 110 minutes (81 minutes scan time). Conclusions: The MRL protocol accurately visualizes both deep and superficial lymphatic vessels showing their characteristic appearances with high spatial resolution, indicating the MRL can be of value in diagnosing and staging peripheral lymphedema.

68Ga-NOTA-Evans Blue PET/CT findings in lymphangioleiomyomatosis compared with 99mTC-ASC lymphoscintigraphy: a prospective study

Background

Lymphangioleiomyomatosis (LAM) is a rare multisystem disease characterized by cystic lung disease and extrapulmonary manifestations, including lymphatic system disorder. The objective of this study was to investigate the findings of ⁶⁸Ga-NOTA-Evans Blue (NEB) PET/CT in LAM and compare it with that of ^99mTc-ASC lymphoscintigraphy.

Methods

Ten patients diagnosed with LAM according to the American Thoracic Society/Japanese Respiratory Society guidelines for LAM were recruited in this study. PET/CT acquisition was performed at 20 to 40 min after subcutaneous injection of ⁶⁸Ga-NEB into the first interdigital spaces of both feet (0.3 ml, 37 MBq/foot). All subjects also underwent ^99mTc-antimony sulfide colloid (ASC) lymphoscintigraphy within a week for comparison.

Results

⁶⁸Ga-NEB PET/CT displayed various lymphatic system abnormalities in 10 (100%) of 10 patients. These included pulmonary lymphatic abnormalities in 10 (100%) of 10 patients, enlarged lymph nodes in 5 (50%), lymphangioleiomyomas in 2 (20%), dilation of the lumbar trunk and/or iliac lymph vessels in 5 (50%), thoracic duct dilation in 2 (20%), chylous effusion in 1 (10%). For pulmonary lymphatic abnormalities, the positive rates of ⁶⁸Ga-NEB PET/CT and ^99mTc-ASC lymphoscintigraphy were 100% (10/10) and 10% (1/10), respectively (P < 0.001). As for the 7 patients with extrapulmonary lymphatic manifestations, ⁶⁸Ga-NEB PET/CT also presented more information than ^99mTc-ASC lymphoscintigraphy.

Conclusion

⁶⁸Ga-NEB PET/CT visualized pulmonary lymphatic abnormality and displayed extrapulmonary lymphatic system disorders of LAM, and might play a role in the diagnosis and evaluation of the disease. ⁶⁸Ga-NEB PET/CT is advantageous over conventional ^99mTc-ASC lymphoscintigraphy in LAM by providing more detailed information of lymphatic dysfunction.

Use of magnetic resonance imaging lymphangiography for preoperative planning in lymphedema surgery: A systematic review

BACKGROUND

In recent years, magnetic resonance imaging lymphangiography (MRL) has emerged as a way to predict if patients are candidates for lymphedema surgery, particularly lymphovenous anastomosis (LVA). Our goal was to conduct a systematic review of the literature on the use of MRL for preoperative planning in lymphedema surgery. We hypothesized that MRL could add valuable information to the standard preoperative evaluation of lymphedema patients.

METHODS

On February 17, 2020, we conducted a systematic review of the PubMed/MEDLINE, Cochrane Clinical Answers, and Embase databases, without time frame or language limitations, to identify articles on the use of MRL for preoperative planning of lymphedema surgery. We excluded studies that investigated other applications of magnetic resonance imaging, such as lymphedema diagnosis and treatment evaluation. The primary outcome was the examination capacity to identify lymphatic anatomy and the secondary outcome was the presence of adverse effects.

RESULTS

Of 372 potential articles identified with the search, nine studies fulfilled the eligibility criteria. A total of 334 lymphedema patients were enrolled in these studies. Two studies compared MRL findings with those of other standard examinations (indocyanine green lymphography [ICG-L] or lymphoscintigraphy). No adverse effects due to MRL were reported. A study shown that MRL had higher sensitivity to detect lymphatic vessel abnormalities compared with lymphoscintigraphy and a statistically higher chance of successful LVA was observed when the results of MRL agreed with those of ICG-L (p < .001).

CONCLUSIONS

MRL could be useful for preoperative planning in lymphedema surgery. The scientific evidence has been limited, so further studies with greater numbers of patients and cost analysis are necessary to justify the addition of MRL to current preoperative protocols.

A systematic review of magnetic resonance lymphography for the evaluation of peripheral lymphedema

OBJECTIVE

Visualization of the lymphatic system is necessary for both early diagnosis and associated treatments. A promising imaging modality is magnetic resonance lymphography (MRL). The aim of this review was to summarize different MRL protocols, to assess the clinical value in patients with peripheral lymphedema, and to define minimal requirements necessary for visualization of lymphatics.

METHODS

A systematic literature search was conducted in PubMed, Embase, and the Cochrane Library in December 2018. Studies performing MRL in patients with peripheral lymphedema or healthy participants were included. Study design, population, etiology, duration of lymphedema, clinical staging, contrast agent, dose, injection site, and technical magnetic resonance imaging details were analyzed. No meta-analyses were performed because of different study aims and heterogeneity of the study populations.

RESULTS

Twenty-five studies involving 1609 patients with both primary lymphedema (n = 669) and secondary lymphedema (n = 657) were included. Upper and lower limbs were examined in 296 and 602 patients, respectively. Twenty-two studies used a gadolinium-based contrast agent that was injected intracutaneously or subcutaneously in the interdigital web spaces. Contrast-enhanced T1-weighted combined with T2-weighted protocols were most frequently used. T1-weighted images showed lymphatics in 63.3% to 100%, even in vessels with a diameter of ≥0.5 mm. Dermal backflow and a honeycomb pattern were clearly recognized.

CONCLUSIONS

MRL identifies superficial lymphatic vessels with a diameter of ≥0.5 mm with high sensitivity and specificity and accurately shows abnormal lymphatics and lymphatic drainage patterns. Therefore, MRL could be of clinical value in both early and advanced stages of peripheral lymphedema. Minimum requirements of an MRL protocol should consist of a gadolinium-based contrast-enhanced T1-weighted gradient-recalled echo sequence combined with T2-weighted magnetic resonance imaging, with acquisition at least 30 minutes after injection of contrast material.

Combined 68Ga-NOTA-Evans Blue Lymphoscintigraphy and 68Ga-NOTA-RM26 PET/CT Evaluation of Sentinel Lymph Node Metastasis in Breast Cancer Patients

In this study, we applied a new strategy to identify sentinel lymph node (SLN) metastasis by combining ⁶⁸Ga-NOTA-Evans Blue (⁶⁸Ga-NEB) for SLN mapping and ⁶⁸Ga-NOTA-RM26 for LN metastasis detection in breast cancer patients. A total of 24 female patients with breast cancer diagnosed by core biopsy or suspected by mammography or ultrasonography were recruited and provided informed consent. All patients underwent ⁶⁸Ga-NEB and ⁶⁸Ga-NOTA-RM26 PET/CT imaging. Visual analysis of ⁶⁸Ga-NEB PET/CT images was used to determine SLNs, and then compared with the ⁶⁸Ga-NOTA-RM26 results and histopathological findings. SLNs were visualized in 24 of 24 patients (100.0%) within 4.0-10.0 (5.6 ± 1.4) min. All patients were pathologically diagnosed with breast cancer, and 12 patients had ipsilateral lymph node metastasis. By combining ⁶⁸Ga-NEB and ⁶⁸Ga-NOTA-RM26 images, 7/12 (58.3%) patients showed mild to intense uptake of ⁶⁸Ga-NOTA-RM26 in SLNs, 1/12 patient (8.3%) had moderate uptake of ⁶⁸Ga-NOTA-RM26 in the non-SLNs rather than SLN, indicating possible bypass lymphatic drainage, partially accounting for the false negatives in SLN biopsy during surgery. No false positives were found. The SUV_max of ⁶⁸Ga-NOTA-RM26 activity in metastatic SLNs was significantly higher than that in non-metastatic SLNs (2.2 ± 2.3 vs 0.7 ± 0.1, P = 0.047). This study manifests the value of combination of ⁶⁸Ga-NEB and ⁶⁸Ga-NOTA-RM26 dual tracer PET/CT in preoperative evaluation of SLN metastasis in breast cancer patients, especially in those patients with lymphatic obstruction and bypass drainage. In general, positive ⁶⁸Ga-NOTA-RM26 uptake in either SLN or other lymph nodes can apply lymph node dissection rather than intraoperative SLN biopsy.

Supermicrosurgical Lymphaticovenous Anastomosis as Alternative Treatment Option for Moderate-to-Severe Lower Limb Lymphedema

BACKGROUND

Supermicrosurgical lymphaticovenous anastomosis (LVA) alleviates lymphedema by draining stagnant lymph from the lymphatic vessels into the venous system. Nevertheless, LVA is believed to be unsuitable for treating moderate-to-severe lymphedema presenting diffuse-pattern dermal backflow (DB). Dermal backflow is considered to be the sign of superficial lymphatic functional failure that renders LVA ineffective. Based on a current algorithm, a more invasive vascularized lymph node flap transfer is recommended instead of LVA. This retrospective study aimed to further investigate and possibly challenge this concept.

STUDY DESIGN

One-hundred patients with unilateral lymphedematous lower limbs who underwent LVA were included. Patients were divided into Group I (10 patients with mild lymphedema) and Group II (90 patients with moderate-to-severe lymphedema). Demographic data and intraoperative findings were recorded. The post-LVA volume reductions by magnetic resonance volumetry were recorded and analyzed.

RESULTS

Preoperatively, significant differences were found in BMI (20.6 vs 26.0 kg/m², p = 0.004) and the volume gained in the lymphedematous limb (396.8 mL vs 1,056.8 mL, p = 0.005) between Groups I and II. Postoperatively, a significant median post-LVA volume reduction (-282.0 mL vs -763.5 mL, p = 0.022) was found in Group II. However, there were no differences in the percentages of post-LVA volume reduction (-43.8% vs -36.4%, p = 0.793) in Groups I and II.

CONCLUSIONS

The use of supermicrosurgical LVA is as effective at treating moderate-to-severe lymphedema as milder lymphedema. The indication for LVA should be broadened to include such cases.

68Ga-NOTA-Evans Blue TOF PET/MR Lymphoscintigraphy Evaluation of the Severity of Lower Limb Lymphedema

PURPOSE

This study was designed to investigate the role of Ga-NOTA-Evans Blue (NEB) time-of-flight (TOF) PET/MR in evaluating lower limb lymphedema by visual analysis and novel parameters.

METHODS

Thirteen patients with unilateral lower limb lymphedema were divided into 3 groups according to the clinical severity: minimal (4 patients), moderate (5 patients), and severe (4 patients). All patients underwent Ga-NEB TOF PET/MR lymphoscintigraphy. The ratio of the standardized uptake value (SUV) of superficial lymphatic vessel (SLV) versus SUV of deep lymphatic vessel (DVL) (SUVslv/dlv) was designed to assess the level of lymphedema severity. The correlation between lymphedema severity and lymphoscintigraphy findings was determined using 1-way analysis of variance, the t test, and Pearson correlation analysis.

RESULTS

There was a significant difference in the SUVslv between the affected limbs and normal limbs in all subjects (affected limbs: 0.57 ± 0.32, normal limbs: 1.86 ± 1.43; P < 0.05), which was not found in the SUVdlv (affected limbs: 0.64 ± 0.39, normal limbs: 0.63 ± 0.31; P > 0.1). The SUVslv/dlv of the affected limbs showed statistical differences within the 3 groups (P < 0.05) (minimal group: 1.91 ± 0.45; moderate group: 0.84 ± 0.16; severe group: 0.42 ± 0.11). The statistical analysis revealed a negative correlation between SUVslv/dlv and the severity of lymphedema (r = -0.899; P < 0.01).

CONCLUSIONS

Ga-NEB TOF PET/MR lymphoscintigraphy can provide anatomical and functional information of lymphatic vessels to guide surgery plans. SUVslv/dlv was well correlated with clinical lymphedema severity and might be potential in evaluating bilateral lower limb lymphedema.

Prostate-Specific Membrane Antigen Accumulation in Lower Extremity Lymphedema

Prostate-specific membrane antigen (PSMA) is overexpressed in a majority of prostate cancer cells, which has led to the development of radiolabeled small-molecule inhibitors of PSMA for molecular imaging and targeted radioligand therapy. Lu-labeled PSMA, with therapeutic β-emission and concomitant γ radiation, permits posttherapy imaging for the assessment of biodistribution and uptake in tumors and normal organs, as well as dosimetry. We report a patient with prostate cancer and metastatic lymph nodes-related lower extremity lymphedema, who presented with dermal backflow and soft-tissue uptake in the lower extremity on posttherapeutic whole body scan after intravenous Lu-PSMA treatment.

Hemolymphangioma involving bones and bladder detected on 68Ga-NEB PET/CT: A rare case report

RATIONALE

Hemolymphangioma is a rare developmental defect of combined vasal and lymphatic vasculature. It is very rare that hemolymphangioma affects the bones and bladder simultaneously, and this condition has never been reported in PubMed.

PATIENT CONCERNS

A 12-year-old male has a history of hospitalization for recurrent episodes of chyluria of 8 years duration and progressively worsening gross hematuria with right hip pain for 6 months.

DIAGNOSIS

Chylous test of urine fluid was positive. There was no organic disease in the kidneys. Ga-NOTA-Evans Blue (NEB) positron emission tomography/computed tomography (PET/CT) images demonstrated clearly several round and strip-shaped low-density shadows with mildly increased radioactive uptake in both bladder wall and pelvis, including sacral, pubic, and ischial bones. Histopathological analysis of biopsy on pubic and ischial bones confirmed the diagnosis of hemolymphangioma.

INTERVENTIONS

The patient received treatment with traditional Chinese medicine.

OUTCOMES

At the 6-month follow-up visit, the patient's symptoms of chyluria, hematuria, and pain were all mitigated.

LESSONS

Hemolymphangioma is a rare benign disease. Ga-NEB PET/CT is a specific method for the lymphatic system, and it might provide more accurate and comprehensive information about the disorder of the lymphatic system compared with CT and magnetic resonance imaging. When patients suffer from suspected lesions of the lymphatic system, Ga-NEB PET/CT might be recommended.

Radioligand Therapy of Prostate Cancer with a Long-Lasting Prostate-Specific Membrane Antigen Targeting Agent 90Y-DOTA-EB-MCG

Several radioligands targeting prostate-specific membrane antigen (PSMA) have been clinically introduced as a new class of radiotheranostics for the treatment of prostate cancer. Among them, ((( R)-1-carboxy-2-mcercaptoethyl)carbamoyl)-l-glutamic acid (MCG) has been successfully labeled with radioisotopes for prostate cancer imaging. The aim of this study is to conjugate MCG with an albumin binding moiety to further improve the in vivo pharmacokinetics. MCG was conjugated with an Evans blue (EB) derivative for albumin binding and a DOTA chelator. PSMA positive (PC3-PIP) and PSMA negative (PC3) cells were used for both in vitro and in vivo studies. Longitudinal PET imaging was performed at 1, 4, 24, and 48 h post-injection to evaluate the biodistribution and tumor uptake of ⁸⁶Y-DOTA-EB-MCG. DOTA-EB-MCG was also labeled with ⁹⁰Y for radionuclide therapy. Besides tumor growth measurement, tumor response to escalating therapeutic doses were also evaluated by immunohistochemistry and fluorescence microscopy. Based on quantification from ⁸⁶Y-DOTA-EB-MCG PET images, the tracer uptake in PC3-PIP tumors increased from 22.33 ± 2.39%ID/g at 1 h post-injection (p.i.), to the peak of 40.40 ± 4.79%ID/g at 24 h p.i. Administration of 7.4 MBq of ⁹⁰Y-DOTA-EB-MCG resulted in significant regression of tumor growth in PSMA positive xenografts. No apparent toxicity or body weight loss was observed in all treated mice. Modification of MCG with an Evans blue derivative resulted in a highly efficient prostate cancer targeting agent (EB-MCG), which showed great potential in prostate cancer treatment after being labeled with therapeutic radioisotopes.

Safety, Pharmacokinetics, and Dosimetry of a Long-Acting Radiolabeled Somatostatin Analog 177Lu-DOTA-EB-TATE in Patients with Advanced Metastatic Neuroendocrine Tumors

Radiolabeled somatostatin analog therapy has become an established treatment method for patients with well to moderately differentiated unresectable or metastatic neuroendocrine tumors (NETs). The most frequently used somatostatin analogs in clinical practice are octreotide and octreotate. However, both peptides showed suboptimal retention within tumors. The aim of this first-in-humans study is to explore the safety and dosimetry of a long-acting radiolabeled somatostatin analog, ¹⁷⁷Lu-1, 4, 7, 10-tetra-azacyclododecane-1, 4, 7, 10-tetraacetic acid-Evans blue-octreotate (¹⁷⁷Lu-DOTA-EB-TATE). Methods: Eight patients (6 men and 2 women; age range, 27-61 y) with advanced metastatic NETs were recruited. Five patients received a single dose, 0.35-0.70 GBq (9.5-18.9 mCi), of ¹⁷⁷Lu-DOTA-EB-TATE and underwent serial whole-body planar and SPECT/CT scans at 2, 24, 72, 120, and 168 h after injection. The other 3 patients received intravenous injection of 0.28-0.41 GBq (7.5-11.1 mCi) of ¹⁷⁷Lu-DOTATATE for the same imaging acquisition procedures at 1, 3, 4, 24, and 72 h after injection. The dosimetry was calculated using the OLINDA/EXM 1.1 software. Results: Administration of ¹⁷⁷Lu-DOTA-EB-TATE was well tolerated, with no adverse symptoms being noticed or reported in any of the patients. Compared with ¹⁷⁷Lu-DOTATATE, ¹⁷⁷Lu-DOTA-EB-TATE showed extended circulation in the blood and achieved a 7.9-fold increase of tumor dose delivery. The total-body effective doses were 0.205 ± 0.161 mSv/MBq for ¹⁷⁷Lu-DOTA-EB-TATE and 0.174 ± 0.072 mSv/MBq for ¹⁷⁷Lu-DOTATATE. Significant dose delivery increases to the kidneys and bone marrow were also observed in patients receiving ¹⁷⁷Lu-DOTA-EB-TATE compared with those receiving ¹⁷⁷Lu-DOTATATE (3.2 and 18.2-fold, respectively). Conclusion: By introducing an albumin-binding moiety, ¹⁷⁷Lu-DOTA-EB-TATE showed remarkably higher uptake and retention in NETs as well as significantly increased accumulation in the kidneys and red marrow. It has great potential to be used in peptide receptor radionuclide therapy for NETs with lower dose and less frequency of administration.