Dual Tracer Research Articles

Cryptic kin discrimination during communal lactation in mice favours cooperation between relatives

Breeding females can cooperate by rearing their offspring communally, sharing synergistic benefits of offspring care but risking exploitation by partners. In lactating mammals, communal rearing occurs mostly among close relatives. Inclusive fitness theory predicts enhanced cooperation between related partners and greater willingness to compensate for any partner under-investment, while females are less likely to bias investment towards own offspring. We use a dual isotopic tracer approach to track individual milk allocation when familiar pairs of sisters or unrelated house mice reared offspring communally. Closely related pairs show lower energy demand and pups experience better access to non-maternal milk. Lactational investment is more skewed between sister partners but females pay greater energetic costs per own offspring reared with an unrelated partner. The choice of close kin as cooperative partners is strongly favoured by these direct as well as indirect benefits, providing a driver to maintain female kin groups for communal breeding.

Quantifying Net Community Production and Calcification at Station ALOHA Near Hawai'i: Insights and Limitations From a Dual Tracer Carbon Budget Approach

AbstractA budget approach is used to disentangle drivers of the seasonal mixed layer carbon cycle at Station ALOHA (A Long‐term Oligotrophic Habitat Assessment) in the North Pacific Subtropical Gyre (NPSG). The budget utilizes data from the WHOTS (Woods Hole—Hawaii Ocean Time‐series Site) mooring, and the ship‐based Hawai'i Ocean Time‐series (HOT) in the NPSG, a region of significant oceanic carbon uptake. Parsing the carbon variations into process components allows an assessment of both the proportional contributions of mixed layer carbon drivers and the seasonal interplay of drawdown and supply from different processes. Annual net community production reported here is at the lower end of previously published data, while net community calcification estimates are 4‐ to 7‐fold higher than available sediment trap data, the only other estimate of calcium carbonate export at this location. Although the observed seasonal cycle in dissolved inorganic carbon in the NPSG has a relatively small amplitude, larger fluxes offset each other over an average year. Major supply comes from physical transport, especially lateral eddy transport throughout the year and entrainment in the winter, offset by biological carbon uptake in the spring. Gas exchange plays a smaller role, supplying carbon to the surface ocean between Dec‐May and outgassing in Jul‐Oct. Evaporation‐precipitation (E‐P) is variable with precipitation prevailing in the first half and evaporation in the second half of the year. The observed total alkalinity signal is largely governed by E‐P with a somewhat stronger net calcification signal in the wintertime.

Somatostatin Receptor Targeted PET-CT and Its Role in the Management and Theranostics of Gastroenteropancreatic Neuroendocrine Neoplasms

Somatostatin receptor (SSTR) agonist-based Positron Emission Tomography-Computed Tomography (PET-CT) imaging is nowadays the mainstay for the assessment and diagnostic imaging of neuroendocrine neoplasms (NEN), especially in well-differentiated neuroendocrine tumors (NET) (World Health Organization (WHO) grade I and II). Major clinical indications for SSTR imaging are primary staging and metastatic workup, especially (a) before surgery, (b) detection of unknown primary in metastatic NET, (c) patient selection for theranostics and appropriate therapy, especially peptide receptor radionuclide therapy (PRRT), while less major indications include treatment response evaluation on and disease prognostication. Dual tracer PET-CT imaging using SSTR targeted PET tracers, viz. [68Ga]Ga-DOTA-Tyr3-Octreotate (DOTA-TATE) and [68Ga]Ga-DOTA-NaI3-Octreotide (DOTA-NOC), and fluorodeoxyglucose (FDG), have recently gained widespread acceptance for better assessment of whole-body tumor biology compared to single-site histopathology, in terms of being non-invasive and the ability to assess inter- and intra-tumoral heterogeneity on a global scale. FDG uptake has been identified as independent adverse risk factor in various studies. Recently, somatostatin receptor antagonists have been shown to be more sensitive and specific in detecting the disease. The aim of this review article is to summarize the clinical importance of SSTR-based imaging in the clinical management of neuroendocrine and related tumors.

Subserosal Indocyanine Green Plus Submucosal Carbon Nanoparticle Navigated Laparoscopic Gastrectomy (DANCE-01): a Cohort Study

BackgroundIndocyanine green (ICG) and carbon nanoparticle (CN) have been widely used for radical gastrectomy. However, synchronous application of ICG and CN in gastrectomy has not been tried yet. For the first time, we herein reported a novel strategy using dual tracers in laparoscopic radical gastrectomy. MethodsThis is a single-center, single-armed, prospective study. For each qualified patient, submucosal CN was injected the day before surgery, and subserosal ICG was injected immediately before surgery. Standard D2 laparoscopic gastrectomy and lymph node examination were subsequently performed. Demographics, lymph nodes (LNs) and postoperative outcome were collected for analysis. To analyze the safety and efficacy of this novel strategy, two contemporary historic control groups using single tracer were established. ResultsA total of 60 patients underwent dual tracer laparoscopic gastrectomy and were divided into distal (n = 41) and total (n = 19) groups. An average of 53.3 and 62.2 LNs was harvested from two groups, respectively. The average operation duration was 213.3 and 250.0 min, and intra-operative blood loss was 100.2 ml and 94.7 ml. None received combined organ resection. Margin negativity and R0 resection were achieved in all patients. Three (7.3%) complications occurred in distal group. None required second operation or deceased. Postoperative hospitalization was 9.7 and 9.6 days, respectively. Compared to single tracer, more LNs (p < 0.01), shorter operation time (p < 0.01), less blood lost (p < 0.01) and accelerated postoperative recovery (p < 0.01) were observed in dual tracer group. ConclusionsWe propose a novel, feasible and safe tracing strategy for laparoscopic gastrectomy. Clinical Trial RegistrationChinese Clinical Trial Registry (ChiCTR2100051309).

Prospective evaluation of the utility of concurrent 18F-FDG PET/CT and 68Ga-DOTA-TOC imaging in gastroenteropancreatic neuroendocrine neoplasms (GEPNENs): The PETNET study.

4022 Background: Somatostatin receptor imaging (SRI) is a standard of care for patients with GEPNETs. The additional value of concurrent 18F-FDG PET/CT (FDG PET) remains unclear. We reviewed a prospective functional imaging study to determine the utility of FDG PET in GEPNENs. Methods: PETNET is a prospective study in British Columbia, Canada, which provides all 68Ga-DOTA-TOC (DOTA PET) imaging in the province. Every patient receives a DOTA PET scan and an FDG PET within 30 days. PETNET enrolls all patients with an indication for SRI. Scans are ordered per treating physician discretion at any point in the disease course. This abstract focuses on the WD-GEPNEN population. Only the first dual functional imaging scans were analyzed and FDG was interpreted qualitatively (positive/negative). Results: From 04/2017-01/2023, 375 patients with NEN were enrolled, 165 (44%) with metastatic GEPNENs. Baseline characteristics are described. Median time between scans was 4 days (IQR 1-11). The proportion of patients with positive FDG PET at baseline increased with WHO grade. For patients with well differentiated G1 to G3 GEPNENs (N=161), overall survival was significantly lower with a positive FDG PET (HR: 4.22; 95%CI 1.61-11.02 p=0.001). FDG remained prognostic when G3 tumors were excluded (N=148) (HR 3.52; 95%CI 1.32-9.42 p= 0.007). When analyzing dual tracer PET imaging, patients with DOTA+/FDG- had reduced risk of dying in comparison with DOTA+/FDG+ (HR:0.26; 95%CI 0.09-0.67 p=0.01). After multivariate analysis, FDG positivity remained independently associated with reduced survival (HR 2.87; 95%CI 1.06-7.75 p=0.04) when controlling for grade of tumor and age. Conclusions: In this prospective cohort of metastatic GEPNENs, a positive FDG PET was significantly associated with reduced overall survival. These results provide additional evidence to support dual tracer functional imaging use in metastatic well differentiated GEPNEN’s. [Table: see text]

Application of fluorescence endoscopy with methylene blue dye and indocyanine green dual-tracer method in sentinel lymph node biopsy for women with breast cancer.

Indocyanine green (ICG) allows for the real-time visualization of lymphatic drainage and provides favorable performance for sentinel lymph node (SLN) mapping. However, the limited ability of tissue penetration of the near-infrared fluorescence of ICG may lead to the failure of lymph node detection in the traditional open approach of sentinel lymph node biopsy (SLNB) for breast cancer, especially in overweight or obese patients. To accurately and quickly detect SLNs, we applied fluorescence endoscopy with a dual-tracer method using ICG and methylene blue dye (MBD) in SLNB for breast cancer. We conducted this study to assess the feasibility and application value of this method in minimally invasive surgery. A total of 117 patients who received dual-tracer injection of ICG and MBD prior to endoscopic SLNB from November 2020 to September 2021 were examined in this study. The number of SLNs identified, the SLN identification rate, the time to identify the first SLN, the procedure duration, and the postoperative morbidity were analyzed. Biopsied SLNs could be identified in 116 patients (99.15%) with an average number of 5.12±1.87 per patient. Blue-stained SLNs were found in 99 patients (84.62%) and fluorescent SLNs in 112 patients (95.73%). A total of 34 patients (29.06%) had positive SLNs. In 6 cases (5.13%), the positive SLNs were only stained with ICG fluorescence. In 1 case (0.85%), the positive SLNs were only blue-stained with no fluorescence staining. The mean durations for the identification of the first SLN and endoscopic SLNB were 7.14±6.31 and 37.75±16.94 min, respectively. Upper-limb lymphoedema was observed 5 cases (4.27%) during a median follow-up period of 10 months. The fluorescence endoscopy method assisted by dual tracer facilitates SLN detection with a comparatively short procedure duration and low complication rate. This approach could serve as a new method for SLNB for patients with breast cancer.

Invited Commentary: De-escalation of axillary surgery in node-positive breast cancer patients after neoadjuvant therapy

The surgical management of patients presenting with node-positive breast cancer who receive neoadjuvant chemotherapy has been an area of focus and debate as neoadjuvant chemotherapy regimens increasingly eradicate the nodal disease. Axillary lymph node dissection has been the standard surgical approach, which carries morbidity risks of lymphedema, pain, and limited range of motion. Although there has been interest in de-escalating axillary surgery, hurdles must be addressed. The first is finding an accurate way to assess nodal response. Many trials have looked at this using the false negative rate as the defining endpoint, all finding that surgical techniques such as using a dual tracer technique, adding immunohistochemistry, and ensuring removal of the node that had biopsy-confirmed disease at diagnosis can impact the accuracy of minimally invasive approaches to evaluate the axilla. However, the second hurdle of defining the impact of minimizing axillary surgery on locoregional and overall outcomes has yet to be answered. Ongoing trials may give us insights over the next few years.

The Systemic Availability of Indispensable Amino Acids from Orally Ingested Algal and Legume Protein in Young Children at Risk of Environmental Enteric Dysfunction

BackgroundThe digestion and absorption of ingested protein may be reduced in children with environmental enteric dysfunction (EED), reducing systemic amino acid availability for protein synthesis with resultant growth faltering. This has not been directly measured in children with EED and associated growth faltering. ObjectivesTo evaluate the systemic availability of algal (spirulina) and legume (mung bean) indispensable amino acids (IAAs) in children with EED. MethodsIndian children (18–24 mo) from urban slums were assigned to EED (n = 24) or no-EED (control, n = 17) groups based on the lactulose rhamnose test, where the lactulose rhamnose ratio cutoff for diagnosing EED (≥0.068) was the mean + 2SD of its distribution in healthy, age-, and sex-matched children of high socioeconomic status. Fecal biomarkers of EED were also measured. Systemic IAA availability was calculated from the plasma: meal IAA enrichment ratio for each protein. True ileal mung bean IAA digestibility was measured by the dual isotope tracer method using spirulina protein as reference. Co-administration of free 13C6-phenylalanine allowed for estimating true ileal phenylalanine digestibility of both proteins, and a phenylalanine absorption index. ResultsThere was no significant difference (independent t-test) in the systemic IAA availability from spirulina or mung bean protein between EED and no-EED groups. There was no between-group difference in true ileal phenylalanine digestibility and its absorption index, or in mung bean IAA digestibility. ConclusionsThe systemic IAA availability of algal and legume protein, or the latter’s IAA/phenylalanine digestibility, is not significantly reduced in children with EED and does not correlate with linear growth.This study was registered in Clinical Trials Registry of India (CTRI) with registration number: CTRI/2017/02/007921.

Preclinical evaluation of sentinel node localization in the stomach via mannose-labelled magnetic nanoparticles and indocyanine green

BackgroundGastrectomy with extended (D2) lymphadenectomy is considered standard of care for gastric cancer to provide the best possible outcomes and pathologic staging. However, D2 gastrectomy is a technically demanding operation and reported to be associated with increased complications and mortality. Application of sentinel lymph node (SLN) concept in gastric cancer has the potential to reduce patient morbidity; however, SLN techniques are not established for gastrectomy, in part due to lack of practical tracers. An effective and convenient tracer with enhanced SLN accumulation is critically needed.MethodsMannose-labelled magnetic tracer ‘FerroTrace’ and fluorescent dye indocyanine green (ICG) were injected laparoscopically into the stomach submucosa of 8 healthy swine under general anaesthesia. Intraoperative fluorescence imaging was used to highlight draining lymphatic pathways containing ICG, while preoperative T2-weighted MRI and ex vivo magnetometer probe measurements were used to identify nodes containing FerroTrace. Lymphadenectomy was performed either robotically (n = 2) or via laparotomy (n = 6).ResultsMixing ICG and FerroTrace ensured concurrence of fluorescent and magnetic signals in SLNs. An initial trial with robotic dissection removed all magnetic LNs (n = 4). In the subsequent laparotomy study that targeted all ICG-LNs based on intraoperative fluorescence imaging, dissection removed an average of 4.7 ± 1.2 fluorescent, and 2.0 ± 1.3 magnetic LNs per animal. Both MRI and magnetometer detected 100% of SLNs (n = 7). FerroTrace demonstrated high specificity to SLNs, which contained 76 ± 30% of total lymphotropic iron, and 88 ± 20 % of the overall magnetometer signal.ConclusionsThrough utilisation of this dual tracer approach, SLNs were identified via preoperative MRI, visualised intraoperatively with fluorescence imaging, and confirmed with a magnetometer. This combination pairs the sensitivity of ICG with SLN-specific FerroTrace and can be used for reliable SLN detection in gastric cancer, with potential applications in neoadjuvant therapy.Graphical abstract

Divergent projections from locus coeruleus to the corticobasal ganglia system and ventral tegmental area of the adult male zebra finch.

The locus coeruleus (LC) is a small noradrenergic brainstem nucleus that plays a central role in regulating arousal, attention, and performance. In the mammalian brain, individual LC neurons make divergent axonal projections to different brain regions, which are distinguished in part by which noradrenaline (NA) receptor subtypes they express. Here, we sought to determine whether similar organizational features characterize LC projections to corticobasal ganglia (CBG) circuitry in the zebra finch song system, with a focus on the basal ganglia nucleus Area X, the thalamic nucleus DLM, as well as the cortical nuclei HVC, LMAN, and RA. Single and dual retrograde tracer injections reveal that single LC-NA neurons make divergent projections to LMAN and Area X, as well as to the dopaminergic VTA/SNc complex that innervates this CBG circuit. Moreover, in situ hybridization revealed that differential expression of mRNA encoding α2A and α2C adrenoreceptors distinguishes LC-recipient CBG song nuclei. Therefore, LC-NA signaling in the zebra finch CBG circuit employs a similar strategy as in mammals, which could allow a relatively small number of LC neurons to exert widespread yet distinct effects across multiple brain regions.

Air–sea gas exchange in a seagrass ecosystem – results from a 3He ∕ SF6 tracer release experiment

Abstract. Seagrass meadows are some of the most productive ecosystems in the world and could help to mitigate the increase of atmospheric CO2 from human activities. However, understanding the role of seagrasses in the global carbon cycle requires knowledge of air–sea CO2 fluxes and hence knowledge of the gas transfer velocity. In this study, gas transfer velocities were determined using the 3He and SF6 dual tracer technique in a seagrass ecosystem in south Florida, Florida Bay, near Bob Allen Keys (25.02663∘ N, 80.68137∘ W) between 1 and 8 April 2015. The observed gas transfer velocity, normalized for CO2 in freshwater at 20 ∘C, k(600), was 4.8 ± 1.8 cm h−1, which was lower than that calculated from published wind speed/gas exchange parameterizations. The deviation in k(600) from other coastal and offshore regions was only weakly correlated with tidal motion and air–sea temperature difference, implying that wind is the dominant factor driving gas exchange. The lower gas transfer velocity was most likely due to wave attenuation by seagrass and limited wind fetch in the study area. A new wind speed/gas exchange parameterization is proposed (k600=0.143u102), which might be applicable to other seagrass ecosystems and wind-fetch-limited environments.

Single-incision endoscope-assisted breast-conserving surgery and sentinel lymph node biopsy: prospective SINA-BCS cohort study.

The current consensus on surgical treatment for early breast cancer is to ensure oncological safety during surgery while preserving functions and aesthetics1–3. Minimally invasive endoscopic surgery has become widely used in modern surgery4–6. Endoscope-assisted surgery allows incision concealment and scar minimization, thereby optimizing aesthetic outcomes and patient satisfaction7–10. The shortcomings of endoscope-assisted surgery are, however, also prominent, including limited working space, increased surgical difficulty11, prolonged operating time, need for additional laparoscopic instruments, and increased costs9,10,12. This study describes single-incision, non-lipolytic, endoscope-assisted breast-conserving surgery (BCS) and sentinel lymph node biopsy (SLNB), the SINA-BCS technique, and compares its perioperative outcomes and cosmetic properties with those of conventional BCS and SLNB (C-BCS). This single-centre prospective cohort study evaluated the efficacy and benefits of SINA-BCS in patients with breast cancer. The study was approved by ChiECRCT (ChiECRCT20200410) and registered at Chictr.org.cn (ChiCTR2100043403). Written informed consent was obtained from all patients. Women aged 20–80 years with pathologically diagnosed cTis–2 N0 breast cancer, who were treated at the West China Hospital of Sichuan University from July 2020 to September 2022, were included. The decision to perform either SINA-BCS or C-BCS was made jointly by the patients and surgeons. Lumpectomy procedures were the same for SINA-BCS and C-BCS. Dual tracers with radioisotope and blue dye were used for SNLB. The operating space of the axilla was established using a non-liposuction method. A subcutaneous tunnel was gradually created through the lumpectomy incision, and expanded by subcutaneous dissociation of the breast tissue toward the axilla. SLNB of SINA-BCS was performed by means of polar diathermy scissors and ultrasonic scalpels, using the working space established through the subcutaneous tunnel and a specifically designed retractor system (Fig. 1). The radionucleotide probe was also inserted through the same incision to detect hot nodes. For C-BCS, an additional 3–4cm axillary incision was made for SLNB (Fig. S1).

Establishment of a sequential dual tracer 18F‐NaF/18F‐FDG PET protocol for imaging the equine foot

The combination of 18 F-Sodium Fluoride (18 F-NaF) and 18 F-FluoroDeoxyGlucose (18 F-FDG) for positron emission tomography (PET) imaging of the equine foot is appealing for detection of both osseous and soft tissue lesions in a single scan. As the combination of tracers could lead to a loss of information, a sequential approach, consisting in imaging with one tracer prior to injecting the second tracer, might be valuable. The goals of this prospective, methods comparison, exploratory study were to establish the order of tracer injectionandtimingforimaging. Six research horses were imaged under general anesthesia with 18 F-NaF PET, 18 F-FDG PET, dual 18 F-NaF/18 F-FDG PET, and CT. Proper uptake could be identified in tendon lesions as early as 10 min after 18F-FDG injection. Bone uptake was limited when 18F-NaF was injected under general anesthesia, even at 1h after injection, when compared with 18 F-NaF injection prior to anesthesia. The sensitivity and specificity of the dual tracer scans were 0.77 (0.63 to 0.86) and 0.98 (0.96 to 0.99) respectively, to assess 18 F-NaF uptake and 0.5 (0.28 to 0.72) and 0.98 (0.95 to 0.99), respectively, for 18F-FDG uptake. These results suggest that the sequential dual tracer approach is a pertinent technique to optimize the PET data gained from a single anesthetic episode. Based on dynamics of tracer uptake, the optimal protocol consists in injecting 18F-NaF prior to anesthesia, acquire 18F-NaF data then inject 18F-FDG and start acquisition of dual tracer PET data 10 min later. This protocol should be further validated in a larger clinical study.

Abstract OT1-09-02: ATNEC: A multicentre, randomized trial investigating whether axillary treatment can be avoided in T1-3N1M0 breast cancer patients with no residual cancer in the axillary lymph nodes after neoadjuvant chemotherapy

Abstract Background: For patients who are node positive at presentation and are found to have a complete nodal tumour response (ypN0) post-neoadjuvant chemotherapy (NACT), we do not yet know whether local axillary therapy can be modified based on the response to NACT. ATNEC addresses whether axillary treatment can be de-escalated, post-surgery, in T1-3N1M0 breast cancer patients who have no residual nodal disease post-NACT. Methods: Design: ATNEC is a phase III, randomized (1:1), multi-centre trial, with embedded economic evaluation. Patients with proven axillary node metastases on needle biopsy receive NACT followed by sentinel node biopsy (SNB). If the sentinel nodes have converted to ypN0, ATNEC randomizes patients to axillary treatment (nodal radiotherapy [ART] or axillary nodal clearance [ANC]) vs. no further axillary treatment. Stratification: Institution, type of surgery (breast conserving surgery vs mastectomy), receptor status (triple negative vs HER2 positive vs ER positive and/or PR positive and HER2 negative). Inclusion criteria: • Age ≥ 18 • Male or female • T1-3N1M0 breast cancer at diagnosis (pre-NACT) • FNA or core biopsy confirmed axillary nodal metastases at presentation • ER and HER2 status evaluated on primary tumour • Received standard NACT as per local guidelines • Imaging of the axilla to assess response to NACT • Dual tracer SNB post-NACT and at least 3 nodes removed (sentinel nodes and marked node). o If a single tracer is used, the patient is eligible if the involved node is marked pre-NACT and at least 3 nodes removed (including the marked node) o If axillary node sampling is performed following failed localization of sentinel nodes, patient is eligible if at least 3 nodes removed (including the marked node). o If node is not marked, or marked node is not removed, patient is eligible if the histology report shows evidence of down-staging with complete pathological response in at least one node of the 3 removed nodes. • No evidence of nodal metastases post-NACT (ypN0) Exclusion criteria: • Bilateral invasive breast cancer • SNB prior to NACT • Previous ipsilateral axillary nodal surgery • Previous cancer within last 5 years or concomitant malignancy Aims: To assess whether omitting further axillary treatment (ART or ANC) for patients with early stage breast cancer and axillary nodal metastases on needle biopsy - who post NACT have no residual nodal disease on SNB (ypN0) - is non-inferior to axillary treatment in terms of disease-free survival, and whether lymphoedema is reduced at 5 years. Statistical methods: All analyses will be carried out on an intention-to-treat basis to preserve randomization, avoid bias from exclusions and preserve statistical power. Radiotherapy Quality Assurance: ATNEC has in-built radiotherapy QA coordinated by National Radiotherapy Trials QA (RTTQA) group. The RTQA monitors trial protocol compliance ensuring clinical outcomes reflect differences in randomization schedules rather than departures from the protocol. ATNEC is the only trial in the UK that offers QA for IMC radiotherapy. Screening Data: ATNEC collects screening data to monitor acceptance rates and reasons why patients decline the trial to identify ways to improve recruitment. Screening data until 30-Jun-22 shows that 69% of eligible patients were approached (244/354) and, of those approached, 45% were consented (109/244). For the 81 patients who declined, the most common reasons were; preference for axillary treatment (31%), preference for no axillary treatment (10%), no reason documented (23%) and ineligibility (21%). ClinicalTrials.gov: NCT04109079 Target accrual: 1900 Target sites: 100 Trial Status: Recruiting. As of 30-Jun-22: 52 sites open, 158 patients enrolled, 54 randomised. ATNEC is open to new sites and international collaboration. Citation Format: Amit Goyal, Sophie Nicholls, Andrea Marshall, Natalie Hammonds, Duncan Wheatley, Beatrix Elsberger, Janice Rose, Helen-Teresa Edwards, Roeum Butt, Abeer Shaaban, Shama Puri, Samreen Ahmed, Tara Homer, Luke Vale, Julie Bruce, Sophie J. Gasson, Helen Higgins, Janet A. Dunn. ATNEC: A multicentre, randomized trial investigating whether axillary treatment can be avoided in T1-3N1M0 breast cancer patients with no residual cancer in the axillary lymph nodes after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-09-02.

Abstract P2-14-21: NiToNo Study. Evaluation in terms of quality of life and upper extremity functionality after Targeted Axillary Dissection versus lymphadenectomy

Abstract Introduction: Targeted Axillary Dissection (TAD) is the combination of the sentinel lymph node biopsy (SLNB) and retrieval of the clipped node that was proved positive before neoadjuvant treatment (NAT). Previous studies have demonstrated that this approach has a low false-negative rate in patients with cN+ before NAT. Current guidelines recommend axillary radiotherapy in cN+ despite a complete pathological response reported after NAT. Aim: To evaluate if TAD improves the quality of life and arm functionality compared to axillary lymph node dissection (ALND) in patients with cN+ before NAT. Methods: Prospective observational study. The study started in 2017 and ended in 2021. We included patients with one to three suspected lymph nodes and at least one confirmed by fine-needle aspiration. Suspicious lymph nodes were clipped before NAT. After NAT if a complete radiological response was achieved by axillary ultrasound, TAD was performed. During surgery, we used ultrasound-guided marked lymph node dissection and dual tracer SLNB. Clipped and SLN were assessed with intraoperative frozen section H&amp;E, standard H&amp;E, and IHC with CKAE1/AE3. After surgery, the breast tumor board analyzes the pathological findings and the surgical performance. When ITC, micro-metastases, or macro-metastases were found in the nodes, or when surgical performance is considered suboptimal, we proceed to ALND. We assessed QoL with standard forms and upper extremity mobility and lymphedema by physical examination. Results: We analyzed 44 women. Median age 53.9 years old. ALND was performed on 28 patients and TAD on 16 patients. Age and other confounding factors such as (BMI, type of surgery, and type of NAT) were similar in both groups. Median follow-up time: 24 months (5-60). No regional relapse in both groups. The axillary staging is shown in table 1. The surgical procedure and indications for ALND are shown in Table 2. Any patient with a Luminal-A-like profile had an axillary response to NAT and subsequent ALND was performed in all 4 patients. By contrast, patients with HER2 overexpression or triple negatives had better axillary responsiveness and 12/21 were stratified only with TAD. Two patients had a false positive finding on the post-NAT axillary ultrasound (one patient with LuminalB-Her2 positive tumor and one patient with HER2 positive not luminal) and ALND was performed, complete pathological response with only fibrosis was observed. Indications of ALND are shown in table 1. On the questionnaires, health status perception (84.9 TAD vs 65.77 ALND, p=0.02), QoL (83.33 TAD vs 64.29 ALND p=0.03), upped extremity symptoms (8.33% TAD vs 30.16% ALND, p&amp;lt; 0.01) and breast symptoms (14.06% TAD vs 31.25% ALND, p=0.03) are better on TAD than in ALND patients. On physical examination, 11 patients of the ALND group had some alteration in functionality (8 patients had limitation of abduction and 7 patients had lymphedema). By contrast, any alteration was found in the patients staged only with TAD. Conclusions: Targeted axillary dissection reduces posttreatment symptomatology and allows a better quality of life with no axillary relapses though follow-up is short. Patients with Luminal-A-like cancer probably are not good candidates for TAD because of a lack of responsiveness and perhaps another approach must be considered. Table 1: Axillary staging after NAT Table 2: Surgical procedure and indications for lymphadennectomy Citation Format: Laia Vila Homs, MAria Lourdes Carrillo-Guivernau, Catalina Sampol, Gabriel Matheu Capo, Pau CAMARASA, Catalina Serra, Monica Mariño, Angela Tarongí, Octavi Cordoba, Antonia Perelló. NiToNo Study. Evaluation in terms of quality of life and upper extremity functionality after Targeted Axillary Dissection versus lymphadenectomy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-21.

Abstract GS4-02: Oncological Outcomes Following Omission of Axillary Lymph Node Dissection in Node Positive Patients Downstaging To Node Negative with Neoadjuvant Chemotherapy: the OPBC-04/EUBREAST-06/OMA study

Abstract Background: Data on the oncologic safety of omission of axillary lymph node dissection (ALND) in node positive (N+) patients who downstage to ypN0 with neoadjuvant chemotherapy (NAC) is sparse. Additionally, there is no consensus on which axillary staging procedure should be used in this setting, sentinel lymph node biopsy (SLNB) alone or in combination with localization and retrieval of the clipped positive node, also known as targeted axillary dissection (TAD). Whether the reduction in the false negative rate observed with TAD translates into a significant reduction in the rate of axillary recurrence is unknown. We sought to evaluate oncologic outcomes after omission of ALND in a large, real-world cohort of breast cancer (BC) patients and to compare rates of axillary recurrence after SLNB with dual tracer mapping vs. TAD. Methods: Data were collected from 19 centers in the Oncoplastic Breast Consortium (OPBC) and EUBREAST networks. Patients with T1-4 biopsy-proven N1-3 BC who underwent NAC followed by axillary staging with either SLNB with dual tracer mapping or TAD and who were pathologically node negative (ypN0) were included. ypN0 was defined as the absence of any tumor or isolated tumor cells. Competing risk analysis was performed to assess the cumulative incidence rates of axillary recurrence, locoregional recurrence, and any invasive (locoregional or distant) recurrence. Two-year cumulative incidence rates were compared between TAD and SLNB using the Gray’s test. Type I error rate was set to 0.05 (α). Results: We included 785 patients (565 treated with SLNB and 220 with TAD) treated with NAC followed by surgery from 01/2014-12/2020. Median patient age was 50 years. The majority (57%) of patients had clinical T2 tumors, and 95% had N1 disease. Most (55%) were HER2+, and 21% were triple negative. Most patients (81%) received anthracycline and taxane-based chemotherapy regimens, but NAC regimens differed between patients treated with TAD and those treated with SLNB (Table 1). All patients with HER2+ tumors received anti HER2 therapy. Nodal radiotherapy was administered to 76% of patients, and was more common in patients who underwent TAD (82% TAD vs 74% SLNB, p=0.017). Breast pathologic complete response (ypT0/is) was more frequent among those patients that had TAD (80% TAD vs. 66% SLNB, p&amp;lt; 0.001). TAD localization was with wire in 46%, radioactive seed in 40%, ultrasound in 5%, tattoo in 2%, and with a combination of these techniques in 7%. The clipped node was successfully retrieved in 94% of TAD cases. The median number of lymph nodes removed was lower in the TAD group compared to the SLNB group [3 (IQR 3-5) vs 4 IQR 3-5), p&amp;lt; 0.001], as was the median number of sentinel lymph nodes [3 (IQR 2-4) vs 4 IQR 3-5), p&amp;lt; 0.001] (Table 1). The 5-year rates of any axillary recurrence, locoregional recurrence, and any invasive recurrence in the entire cohort were 1.1% (95%CI 0.39-2.4%), 3.1% (95%CI 1.6-5.3%) and 10% (95%CI 7.6-13%), respectively. The two-year cumulative incidence of axillary recurrence did not differ between patients treated with TAD compared to SLNB (0% vs 0.9%, p=0.19). Conclusion: Early axillary recurrence after omission of ALND in patients who successfully downstage from N+ to ypN0 with NAC is a rare event following both SLNB or TAD, and was not significantly lower in TAD than SLNB. Although longer follow-up is needed to confirm these findings, the main advantage of TAD seems to be a reduction in the number of lymph nodes removed. Overall, these results support omission of ALND in patients who successfully downstage to node negative disease after NAC. Table 1: Clinicopathological Features of the Study Cohort, Stratified by Axillary Staging Technique Citation Format: Giacomo Montagna, Mary Mrdutt, Astrid Botty, Andrea V. Barrio, Varadan Sevilimedu, Judy C. Boughey, Tanya L. Hoskin, Laura H. Rosenberger, E Shelley Hwang, Abigail Ingham, Bärbel Papassotiropoulos, Bich Doan Nguyen-Sträuli, Christian Kurzeder, Danilo Diaz Aybar, Denise Vorburger, Dieter Michael Matlac, Edvin Ostapenko, Fabian Riedel, Florian Fitzal, Francesco Meani, Franziska Fick, Jacqueline Sagasser, Jörg Heil, Konstantin J. Dedes, Laszlo Romics, Maggie Banys-Paluchowski, Maria Del Rosario Cueva Perez, Marcelo Chavez Diaz, Martin Heidinger, Mathias K. Fehr, Mattea Reinisch, Nadia Maggi, Nicola Rocco, Nina Ditsch, Oreste Davide Gentilini, Regis Resende Paulinelli, Sebastian Sole Zarhi, Sherko Küemmel, Simona Bruzas, Simona Di Lascio, Tamara Parissenti, Uwe Güth, Valentina Ovalle, Christoph Tausch, Monica Morrow, Thorsten Kühn, Walter P. Weber. Oncological Outcomes Following Omission of Axillary Lymph Node Dissection in Node Positive Patients Downstaging To Node Negative with Neoadjuvant Chemotherapy: the OPBC-04/EUBREAST-06/OMA study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-02.

Chiral Separation of Metolachlor Metabolites in a Single, Large Volume Injection to Facilitate Watershed Tracer Studies

Single injection, chiral analysis of two abundant metolachlor metabolites, metolachlor ethanesulfonic acid (MESA) and metolachlor oxanilic acid (MOXA), was accomplished using 10 mL of water samples, modified from the original 1 L method for MESA analysis alone. These compounds revealed a temporal stamp corresponding to a conversion from racemic to S-enriched metolachlor that can be used to reduce uncertainty and equifinality in modeling watershed cropland response. They offer a dual tracer for watershed processing of nitrate that is derived from a common source and provides utility for sampling and consistency in tracing both time-weighted and long-term processes related to hydrology. Six matched grab sample results compared the 1 L and 10 mL procedures with less than a 12% difference. Average recoveries for the 10 mL method were 94% for the four isomers of MOXA and 96% for the three peaks of MESA. The 10 mL method increases the accessibility of this procedure for water age dating on a larger scale.

The potential application of MR-derived ADCmin values from 68Ga-DOTATATE and 18F-FDG dual tracer PET/MR as replacements for FDG PET in assessment of grade and stage of pancreatic neuroendocrine tumors

BackgroundTo evaluate the utility of 68Ga-DOTATATE and 18F-FDG PET/MR for prediction of grade and stage of pancreatic neuroendocrine tumors (PNETs), and to examine the correlation between parameters obtained from FDG PET and diffusion-weighted imaging (DWI) MR parameters.MethodsA retrospective study using 68Ga-DOTATATE and 18F-FDG PET/MR imaging was performed between April 2020 and May 2022 on 46 individuals with histologically confirmed PNETs. Metabolic tumor volume (MTV), maximum standardized uptake value (FSUVmax), and tumor lesion glycolysis (TLG) for FDG; somatostatin receptor density (SRD), maximum standardized uptake value (GSUVmax), and total lesion somatostatin receptor density (TLSRD) for DOTATATE; and minimum and mean apparent diffusion coefficient (ADCmin and ADCmean) values for MRI, respectively. We performed Spearman’s correlation analysis to examine the links between these variables and primary tumor stage and grading.ResultsHigher PNET grading was associated with higher FSUVmax, MTV, and TLG values (P < 0.05). TLG, SRD, ADCmin, and ADCmean values were correlated with N staging, while SRD, MTV, ADCmin, TLG, and ADCmean were associated with M staging. Notably, ADCmin was a negative correlation between FSUVmax (r = − 0.52; P < 0.001), MTV (r = − 0.50; P < 0.001), and TLG (r = − 0.56; P < 0.001).ConclusionsThis study highlights significant correlative relationships between FDG PET-derived parameters and ADCmin. ADCmin may offer utility as a tool for PNET staging and grading in lieu of FDG PET. 68Ga-DOTATATE PET/MR alone may be a sufficient alternative to dual tracer PET/MR when conducting grading and staging of primary PNETs.

Dual targeting PET tracer [68Ga]Ga-FAPI-RGD in patients with lung neoplasms: a pilot exploratory study.

Rationale: Early discovery, accurate diagnosis, and staging of lung cancer is essential for patients to receive appropriate treatment. PET/CT has become increasingly recognized as a valuable imaging modality for these patients, but there remains room for improvement in PET tracers. We aimed to evaluate the feasibility of using [68Ga]Ga-FAPI-RGD, a dual-targeting heterodimeric PET tracer that recognizes both fibroblast activation protein (FAP) and integrin αvβ3 for detecting lung neoplasms, by comparing it with [18F]FDG and single-targeting tracers [68Ga]Ga-RGD and [68Ga]Ga-FAPI. Methods: This was a pilot exploratory study of patients with suspected lung malignancies. All 51 participants underwent [68Ga]Ga-FAPI-RGD PET/CT, of which: 9 participants received dynamic scans, 44 participants also underwent [18F]FDG PET/CT scan within two weeks, 9 participants underwent [68Ga]Ga-FAPI PET/CT scan and 10 participants underwent [68Ga]Ga-RGD PET/CT scan. The final diagnosis was made based on histopathological analyses and clinical follow-up reports. Results: Among those who underwent dynamic scans, the uptake of pulmonary lesions increased over time. The optimal timepoint for a PET/CT scan was identified to be 2 h post-injection. [68Ga]Ga-FAPI-RGD had a higher detection rate of primary lesions than [18F]FDG (91.4% vs. 77.1%, p < 0.05), higher tumor uptake (SUVmax, 6.9 ± 5.3 vs. 5.3 ± 5.4, p < 0.001) and higher tumor-to-background ratio (10.0 ± 8.4 vs. 9.0 ± 9.1, p < 0.05), demonstrated better accuracy in mediastinal lymph node evaluation (99.7% vs. 90.9%, p < 0.001), and identified more metastases (254 vs. 220). There was also a significant difference between the uptake of [68Ga]Ga-FAPI-RGD and [68Ga]Ga-RGD of primary lesions (SUVmax, 5.8 ± 4.4 vs. 2.3 ± 1.3, p < 0.001). Conclusion: In our small scale cohort study, [68Ga]Ga-FAPI-RGD PET/CT gave a higher primary tumor detection rate, higher tracer uptake, and improved detection of metastases compared with [18F]FDG PET/CT, and [68Ga]Ga-FAPI-RGD also had advantages over [68Ga]Ga-RGD and was non-inferior to [68Ga]Ga-FAPI. We thus provide proof-of-concept for using [68Ga]Ga-FAPI-RGD PET/CT for diagnosing lung cancer. With the stated advantages, the dual-targeting FAPI-RGD should also be explored for therapeutic use in future studies.

Dual imaging agent for magnetic particle imaging and computed tomography.

Magnetic particle imaging (MPI) is a novel biomedical imaging modality that allows non-invasive, tomographic, and quantitative tracking of the distribution of superparamagnetic iron oxide nanoparticle (SPION) tracers. While MPI possesses high sensitivity, detecting nanograms of iron, it does not provide anatomical information. Computed tomography (CT) is a widely used biomedical imaging modality that yields anatomical information at high resolution. A multimodal imaging agent combining the benefits of MPI and CT imaging would be of interest. Here we combine MPI-tailored SPIONs with CT-contrast hafnium oxide (hafnia) nanoparticles using flash nanoprecipitation to obtain dual-imaging MPI/CT agents. Co-encapsulation of iron oxide and hafnia in the composite nanoparticles was confirmed via transmission electron microscopy and elemental mapping. Equilibrium and dynamic magnetic characterization show a reduction in effective magnetic diameter and changes in dynamic magnetic susceptibility spectra at high oscillating field frequencies, suggesting magnetic interactions within the composite dual imaging tracers. The MPI performance of the dual imaging agent was evaluated and compared to the commercial tracer ferucarbotran. The dual-imaging agent has MPI sensitivity that is ∼3× better than this commercial tracer. However, worsening of MPI resolution was observed in the composite tracer when compared to individually coated SPIONs. This worsening resolution could result from magnetic dipolar interactions within the composite dual imaging tracer. The CT performance of the dual imaging agent was evaluated in a pre-clinical animal scanner and a clinical scanner, revealing better contrast compared to a commercial iodine-based contrast agent. We demonstrate that the dual imaging agent can be differentiated from the commercial iodine contrast agent using dual energy CT (DECT) imaging. Furthermore, the dual imaging agent displayed energy-dependent CT contrast arising from the combination of SPION and hafnia, making it potentially suitable for virtual monochromatic imaging of the contrast agent distribution using DECT.