Node Uptake Research Articles

Abstract 4136566: Primary Pericardial Mesothelioma: Diagnostic dilemma and rapid decline

Description of case: A 33-year-old man with no medical history or environment exposures, presented with dyspnea, nausea, and vomiting. He was tachycardic, with jugular venous distension, pulsus paradoxus, low voltage QRS and echocardiogram (TTE) showed a large pericardial effusion with ventricular interdependence. He underwent pericardiocentesis with negative fluid studies, including cytology. Two months later he represented with dyspnea and pleuritic chest pain, was diagnosed with pericarditis, and found to have recurrent pericardial effusion without tamponade. He was treated with aspirin and colchicine and discharged, with surveillance TTE showing a stable pericardial effusion but with significant adhesions and constrictive physiology (confirmed on right heart catheterization). Negative QuantiFERON was obtained and Anakinra started. Two months later he remained symptomatic with new pleural effusions and was sent for positron emission tomography scan which revealed diffuse intensely hypermetabolic pericardial thickening/fluid, up to 3.8 cm in maximal thickness and increased uptake in mediastinal nodes. Next, a cardiac MRI showed extensive circumferential thickening of the pericardial space approximately 2.5 cm in thickness. Both the visceral and parietal pericardium exhibited extensive scattered delayed hyperenhancement. Subsequent pericardial biopsy showed markedly fibrotic pericardium and pathology showed biphasic malignant pericardial mesothelioma. Immunosuppressive medications were stopped, and he underwent thoracentesis. After multidisciplinary discussions, he was started on nivolumab every two weeks and ipilimumab with a plan for surgery based on response to therapy. However, progressive symptoms and worsening constriction physiology led to palliative consultation and comfort care transition, with him dying shortly after. Discussion: Recurrent pericarditis and pericardial effusion, along with negative typical pericardial fluid studies, raised suspicion for a non-benign etiology. Multimodality imaging was employed and led to a pericardial biopsy. Constrictive pericarditis is an uncommon presentation of primary pericardial mesothelioma. Biphasic mesotheliomas from pleural or peritoneal origins are normally treated with systemic therapy with preference for combined immunotherapy. Primary pericardial mesothelioma is associated with a late presentation and high mortality rate, with surgery, if able to be done early appearing to be the recommended approach.

89Zr]Zr-PSMA-617 PET/CT in a Patient with Biochemical Recurrence of Prostate Cancer and Prior Indetermined Findings on [18F]PSMA-1007 Imaging.

We report a case of a 79-year-old male patient with a history of radical prostatectomy for prostate cancer. The patient presented with biochemical reoccurrence; however, previous conventional PSMA PET/CT using [18F]PSMA-1007 showed two indetermined findings with low uptake in the right iliac lymph nodes. Further MRI evaluation provided no additional information. A recently introduced PSMA tracer, [89Zr]Zr-PSMA-617 (half-life: 3.3 days), was administered in an attempt to confirm the diagnosis and aid in potential radiation planning. [89Zr]Zr-PSMA-617 PET/CT clearly revealed the previously indetermined right iliac lymph nodes as definitely metastatic and also identified additional lymph node metastases that were undetected in prior scans. This case highlights the potential superior sensitivity of [89Zr]Zr-PSMA-617 PET/CT in detecting recurrent disease, especially in unclear settings of [18F]PSMA-1007 PET/CT and demonstrates its potential for guiding targeted radiation therapy with curative intent.

Characterizing Normal Upper Extremity Lymphatic Flow with 99mTc In-House Dextran: A Retrospective Study.

Lymphoscintigraphy evaluates the lymphatic system using radiocolloid compounds like 99mTc-sulfur colloid and 99mTc-nanocolloid, which vary in particle size and distribution timing. A local in-house Dextran kit (15-40 nm) was developed in 2005 and began clinical use in 2008 to localize sentinel lymph nodes; diagnose lymphedema; and detect lymphatic leakage. The normal drainage pattern remains unexplored. We retrospectively analyzed 84 upper extremity lymphoscintigraphies from 2008 to 2021. 99mTc in-house Dextran was intradermally injected into both hands, followed by whole-body imaging at specified intervals (≤15 min; 16-30 min; 31-45 min; 46-60 min), with some receiving delayed imaging. Visual and quantitative analyses recorded axillary and forearm lymph nodes and liver, kidney, and urinary bladder activity. Results showed 92% (77/84) upper extremity lymphatic tract visualization within 45 min. Axillary node detection rates increased from 46% (≤15 min) to 86% (46-60 min). Delayed imaging further revealed nodes. Epitrochlear or brachial node visualization was rare (4%, 3/84). Hepatic, renal, and urinary bladder activity was noted in 54%, 71%, and 93% at 1 h, respectively. The axillary node uptake ratio was minimal (<2.5% of injection site activity; median 0.33%). This study characterizes normal upper extremity lymphatic drainage using 99mTc in-house Dextran, offering insights into its clinical application.

Use of Laxative-Augmented Contrast Medium Increases the Accuracy in the Detection of Colorectal Neoplasms.

Colonic adenomas are considered a precursor of colorectal cancer. A 75-year-old woman had a history of post-operation left breast cancer. She received an excision when the left chest wall recurred. A later FDG PET/CT scan revealed a focal intense FDG accumulation in the sigmoid, a focal mild FDG uptake in the pericolic lymph node, and a focal increased FDG accumulation in the transverse colon. A delayed FDG PET/CT scan after the per-rectal administration of the laxative-augmented contrast medium revealed a filling defect with persistent FDG uptake in the sigmoid and transverse colon and mild FDG uptake in the pericolic lymph node. In addition, more lesions were observed in the rectum and descending colon. The pathology reports showed sigmoid adenocarcinoma with lymph node metastasis, and adenomas in the transverse colon, descending colon, and rectum.

Correlation of tracer uptake in sentinel lymph nodes as measured on SPECT/CT and during intra-operative gamma tracing with SENSEI: the UZ Leuven experience

Correlation of tracer uptake in sentinel lymph nodes as measured on SPECT/CT and during intra-operative gamma tracing with SENSEI: the UZ Leuven experience

Evaluating 64Cu-DOTA-rituximab as a PET agent in patients with B-cell lymphoma: a head-to-head comparison with 18F-fluorodeoxyglucose PET/computed tomography.

This study aimed to evaluate the biodistribution of 64Cu-DOTA-rituximab and its diagnostic feasibility for lymphoma using CD20-targeted 64Cu-DOTA-rituximab PET/computed tomography (PET/CT). A prospective study involving six patients diagnosed with lymphoma was conducted between January 2022 and January 2023. These patients underwent 18F-fluorodeoxyglucose (18F-FDG) and 64Cu-DOTA-rituximab PET/CT scans. 64Cu-DOTA-rituximab PET/CT images were acquired at 1, 24, and 48 h after administering 64Cu-DOTA-rituximab to assess the biodistribution and dosimetry over time. The observed lymph nodes were categorized into specific regions, including cervical and supraclavicular, axillary and infraclavicular, mediastinal, hilar, abdominal paraaortic and retroperitoneal, iliac, mesenteric, and inguinal regions, to compare the diagnostic ability of 18F-FDG and 64Cu-DOTA-rituximab PET/CT in detecting lymphoma lesions. Furthermore, the tumor-to-background ratio was calculated and compared with the maximum standardized uptake (SUVmax) of the tumors and the mean standardized uptake (SUVmean) of normal organs. Internal radiation dosimetry was determined using the OLINDA/EXM software. 64Cu-DOTA-rituximab uptake in lymph nodes associated with lymphoma progressively increased from 1 to 48 h after injection. In contrast, 64Cu-DOTA-rituximab uptake in normal organs, such as blood, lung, kidney, bladder, muscle, bone, and brain, decreased over time, whereas it increased in the liver and spleen. When it comes to the comparison between 64Cu-DOTA-rituximab and 18F-FDG, the SUVmax of tumors was higher on 64Cu-DOTA-rituximab PET/CT (18.1 ± 8.3) than on 18F-FDG PET/CT (5.2 ± 1.5). Additionally, the tumor-to-background ratio, measured using the SUVmean of normal muscles, was higher on 64Cu-DOTA-rituximab PET/CT (55.7 ± 31.0) than on 18F-FDG PET/CT (8.6 ± 2.8). No adverse events related to 64Cu-DOTA-rituximab injection were reported. The results of this study demonstrate the feasibility of using 64Cu-DOTA-rituximab PET/CT to evaluate the CD20 expression. The increased 64Cu-DOTA-rituximab uptake in lymph nodes associated with tumors, higher SUVmax, and tumor-to-muscle ratios observed with 64Cu-DOTA-rituximab PET/CT compared with 18F-FDG PET/CT, highlight the diagnostic potential of this imaging modality.

Vaccines combining slow delivery and follicle targeting of antigens increase germinal center B cell clonal diversity and clonal expansion.

Vaccines incorporating slow delivery, multivalent antigen display, or immunomodulation through adjuvants have an important role to play in shaping the humoral immune response. Here we analyzed mechanisms of action of a clinically relevant combination adjuvant strategy, where phosphoserine (pSer)-tagged immunogens bound to aluminum hydroxide (alum) adjuvant (promoting prolonged antigen delivery to draining lymph nodes) are combined with a potent saponin nanoparticle adjuvant termed SMNP (which alters lymph flow and antigen entry into lymph nodes). When employed with a stabilized HIV Env trimer antigen in mice, this combined adjuvant approach promoted substantial enhancements in germinal center (GC) and antibody responses relative to either adjuvant alone. Using scRNA-seq and scBCR-seq, we found that the alum-pSer/SMNP combination both increased the diversity of GC B cell clones and increased GC B cell clonal expansion, coincident with increases in the expression of Myc and the proportion of S-phase GC B cells. To gain insight into the source of these changes in the GC response, we analyzed antigen biodistribution and structural integrity in draining lymph nodes and found that the combination adjuvant approach, but not alum-pSer delivery or SMNP alone, promoted accumulation of highly intact antigen on follicular dendritic cells, reflecting an integration of the slow antigen delivery and altered lymph node uptake effects of these two adjuvants. These results demonstrate how adjuvants with complementary mechanisms of action impacting vaccine biodistribution and kinetics can synergize to enhance humoral immunity.

68Ga-PSMA PET/CT and 18F-FDG PET/CT in the diagnosis of prostatic ductal cancer

PurposesTo explore the characteristics of PSMA PET/CT and FDG PET/CT images in prostatic ductal adenocarcinoma (DA) patients. MethodsWe retrospectively enrolled prostatic DA patients with PET/CT scans at Tongji Hospital from 2018 to 2022. Patients with prostatic acinar adenocarcinoma (AA) and benign pathology (BP) were enrolled by 1:1 matching. Differences in the uptake of primary and metastatic foci on PET among the groups were analyzed. ResultsA total of 42 patients were enrolled: 14 in each group. In primary foci, the mean PSMA uptake in the DA group was lower than that in the AA group (14.2 ± 9.6 vs. 27.1 ± 14.3, P = 0.009) and greater than that in the BP group (14.2 ± 9.6 vs. 4.7 ± 1.3, P = 0.003). The AUCs of the DA-AA ROC curve and DA-BP ROC curve were 0.781 and 0.872, respectively. The median PSMA uptake of metastatic lymph nodes in the DA group was lower than that in the AA group (5.6 vs. 14.2, P = 0.033), with no significant difference in metastatic bone lesions (9.5 vs 19.1, P = 0.485). No significant difference was found in the FDG uptake of primary and metastatic foci between the DA and AA groups (P > 0.05). ConclusionProstatic DA has greater PSMA uptake than BP diseases, but lower uptake in both primary foci and metastatic lymph nodes than AA on PSMA PET/CT, aiding in the differential diagnosis of DA, AA and BP diseases. Clinicians should combine traditional imaging with PSMA PET/CT to avoid underestimating the clinical stage of DA patients.

Physiological biodistribution on Ga68-PSMA PET/CT and the factors effecting biodistribution

AimThe study aims to determine the physiological and pathophysiological distribution of the radiopharmaceutical (Ga68-PSMA-617) and investigate whether there are differences in distribution according to the laboratory, histopathological and clinical findings that can affect image evaluation. Also, we aimed to determine cut-off values to distinguish physiological and pathological uptake in prostate, bone, and lymph nodes.Materials and Methods229 prostate cancer patients who underwent Ga68-PSMA PET/CT at our department were retrospectively analyzed. The patients were grouped according to PET/CT results, Gleason scores, PSA values, received treatments, metastatic status and other laboratory values. The SUV values of the organs, tissues, and pathological lesions of the patients in these subgroups were compared among themselves.ResultsNo significant difference was detected in the physiological uptake of lymph nodes and bone between the groups. In the group with patients that received androgen deprivation therapy (ADT), the bone metastasis SUV values were found to be higher and the SUV values of the submandibular gland and renal cortex were found to be lower (Mann–Whitney U, p = 0.043; 0.004; 0.01, respectively). In the group with patients who received radiotherapy, the normal prostate tissue SUV values were determined to be higher (Mann–Whitney U, p = 0.009). The SUV values of the submandibular gland, muscle, liver, and blood pool were found to be lower in the group of patients with high serum LDH values. The cut-off SUVmax value was determined to be 6.945 (sensitivity 89.6%, specificity 98.1%) for primary prostate lesion; 4.72 for lymph node metastasis; 4.25 for bone metastasis. The serum PSA cut-off value to distinguish the negative/positive groups was found to be 1,505 (sensitivity 79.7%, specificity 77.3%).ConclusionIn conclusion, PSMA-617 demonstrates a similar biodistribution with other PSMA ligands. The physiological uptake of lymph nodes and bone which are mostly metastasized in prostate cancer, are not affected by the factors we examined. It should be kept in mind that the normal prostate tissue uptake may increase in patients receiving radiotherapy, and the physiological/pathological uptake of the organs may differ due to the changes in PSMA expression in patients receiving ADT, tumor burden, and kidney function may affect the biodistribution.

Comparative Uptake Patterns of Radioactive Iodine and [18F]-Fluorodeoxyglucose (FDG) in Metastatic Differentiated Thyroid Cancers.

Background: Metastatic differentiated thyroid cancer (DTC) represents a molecularly heterogeneous group of cancers with varying radioactive iodine (RAI) and [18F]-fluorodeoxyglucose (FDG) uptake patterns potentially correlated with the degree of de-differentiation through the so-called "flip-flop" phenomenon. However, it is unknown if RAI and FDG uptake patterns correlate with molecular status or metastatic site. Materials and Methods: A retrospective analysis of metastatic DTC patients (n = 46) with radioactive 131-iodine whole body scan (WBS) and FDG-PET imaging between 2008 and 2022 was performed. The inclusion criteria included accessible FDG-PET and WBS studies within 1 year of each other. Studies were interpreted by two blinded radiologists for iodine or FDG uptake in extrathyroidal sites including lungs, lymph nodes, and bone. Cases were stratified by BRAF V600E mutation status, histology, and a combination of tumor genotype and histology. The data were analyzed by McNemar's Chi-square test. Results: Lung metastasis FDG uptake was significantly more common than iodine uptake (WBS: 52%, FDG: 84%, p = 0.04), but no significant differences were found for lymph or bone metastases. Lung metastasis FDG uptake was significantly more prevalent in the papillary pattern sub-cohort (WBS: 37%, FDG: 89%, p = 0.02) than the follicular pattern sub-cohort (WBS: 75%, FDG: 75%, p = 1.00). Similarly, BRAF V600E+ tumors with lung metastases also demonstrated a preponderance of FDG uptake (WBS: 29%, FDG: 93%, p = 0.02) than BRAF V600E- tumors (WBS: 83%, FDG: 83%, p = 1.00) with lung metastases. Papillary histology featured higher FDG uptake in lung metastasis (WBS: 39%, FDG: 89%, p = 0.03) compared with follicular histology (WBS: 69%, FDG: 77%, p = 1.00). Patients with papillary pattern disease, BRAF V600E+ mutation, or papillary histology had reduced agreement between both modalities in uptake at all metastatic sites compared with those with follicular pattern disease, BRAF V600E- mutation, or follicular histology. Low agreement in lymph node uptake was observed in all patients irrespective of molecular status or histology. Conclusions: The pattern of FDG-PET and radioiodine uptake is dependent on molecular status and metastatic site, with those with papillary histology or BRAF V600E+ mutation featuring increased FDG uptake in distant metastasis. Further study with an expanded cohort may identify which patients may benefit from specific imaging modalities to recognize and surveil metastases.

68Ga]Ga-ABY-025 PET in HER2-positive breast cancer: Benefits and pitfalls in staging of axillary disease.

1035 Background: [68Ga]Ga-ABY-025 PET showed promising results in quantifying human epidermal growth factor receptor Type 2 (HER2) expression in breast cancer patients [1]. In this study we extend the findings from [68Ga]Ga-ABY-025 PET with data from both treatment-naïve patients and previously treated patients with recurrences, mimicking the clinical situation other sites might encounter when HER2-targeting imaging is made more widely available. The focus of this additional data analysis is on staging, potential pitfalls and changes in uptake patterns associated with previous treatments. Methods: [68Ga]Ga-ABY-025 PET and [18F]-FDG PET images from 50 women with biopsy confirmed HER2 positive breast cancer were examined. Each patient underwent both scans within 1 week. A follow-up [18F]-FDG PET was performed after 2 courses of HER2-targeted treatment to assess metabolic response. Results: Twelve out of 50 patients showed heterogeneous [68Ga]Ga-ABY-025 uptake. Three out of these 12 patients presented with a wider local spread that was only detectable using [68Ga]Ga-ABY-025 PET as distinct uptake in lymph nodes of 2-5 mm size. Based on the additional information from [68Ga]Ga-ABY-025 PET, restaging was evaluated in two of the three cases, both of which had lobular carcinoma, and resulted in modifications in treatment plans. Two patients who received COVID-19 vaccine closely before undergoing PET scans showed high uptake on [18F]-FDG PET in lymph nodes ipsilateral to the vaccine injection site, but not on [68Ga]Ga-ABY-025 PET. Additionally, the physiological [68Ga]Ga-ABY-025 uptake in thyroid gland and axillary sweat glands was inversely correlated with the number of previous treatments and was significantly more pronounced in treatment-naïve patients. Conclusions: [68Ga]Ga-ABY-025 PET provided additional information that, in conjunction with [18F]-FDG PET findings, might help in accurate staging, particularly in cases with very small lymph node metastases. It also helped reduce false positive results as [68Ga]Ga-ABY-025 uptake was so far not seen in any benign inflammatory lesions. Physiological uptake can be seen in thyroid and apocrine glandular tissues but gradually disappear with subsequent HER2-targeted therapies. 1,Alhuseinalkhudhur, A. et al. J Nucl Med, 2023 64(9): p. 1364-1370. Clinical trial information: NCT03655353 .

Distribution and predictors of F-18-FDG uptake values of non-malignant cervical lymph nodes in pediatric patients

BackgroundF-18-flurodeoxyglucose (FDG) PET/CT is routinely used for staging, evaluation of response to treatment and follow-up of most pediatric malignancies. Cervical lymph nodes can be involved in some pediatric malignancies, but increased uptake in non-malignant cervical lymph nodes is not exceptional in this population. The aim of the present study is to identify predictors of the maximum uptake in non-malignant cervical lymph nodes in the pediatric population.Methods191 FDG PET/CT studies of pediatric patients without malignant involvement of cervical lymph nodes were retrospectively reviewed. The maximal Standard Uptake Value in the hottest cervical lymph node (SUVmaxCLN), as well as demographic, technical and imaging variables were recorded. The predictive effect of those variables on SUVmaxCLN was estimated using linear regression models.ResultsIncreased FDG activity in cervical nodes was observed in 136/191 studies (71%). The mean SUVmaxCLN was 2.2 ± 1.3. Ipsilateral palatine tonsil SUVmax, mean liver uptake, and treatment status were all statistically significant predictors of SUVmaxCLN. However, in multivariate regression analysis, only ipsilateral palatine tonsil SUVmax was found to be significant. In addition, SUVmaxCLN was greater than the mean liver uptake in 50% of all studies. This proportion was higher in younger children, reaching 77% of studies of children younger than six years.ConclusionSUVmax in ipsilateral palatine tonsil is a strong predictor of the maximal uptake value of non-malignant cervical lymph nodes in children. The intensity of uptake in non-malignant cervical lymph nodes is frequently higher than liver uptake in children, and this tendency increases for younger patients.Trial was registeredIn the internal hospital registry under TRN 0209-22-HMO on date 23.04.2022.

Characterisations and Scan Findings of Non-Small Cell Lung Cancer Seen on Staging FDG PET-CT: Contemporary Review and Institutional Experience

Objective: Fluorodeoxyglucose (FDG) PET-CT scan is extensively being applied in oncology including lung cancer staging and treatment response assessment by depicting glucose consumption of malignant cells. Non- small cell lung cancer (NSCLC) cases such as adenocarcinoma and squamous cell carcinoma (SCC) are more prevalent. We aimed to determine the FDG uptake avidity based on semiquantitative maximum Standardise Uptake Value (SUVmax) observed on staging PET-CT of newly diagnosed NSCLC and associated contributing factors. Methods: Retrospective review of 125 cases of biopsy proven lung cancer referred for FDG PET-CT in our institution over the past 2 years. Staging PET-CT scans (n=54) were included for analysis. Clinical parameters and PET-CT findings (SUVmax of primary lesion, presence of nodal and metastatic disease) were investigated. SUVmax of primary lesion for SCC and adenocarcinoma was compared. Association between SUVmax of primary lesion and extrapulmonary FDG- avid lesions presence was also determined. Results: Males were predominant (60%). Average age was 62.5 years. Majority were adenocarcinoma (65%) followed by SCC (22%) and others (13%). Mean tumour size was 5.1 cm. Lung SCC demonstrated intensely increased FDG uptake that was significantly higher compared to adenocarcinoma (average SUVmax 24.4 vs SUVmax 15.6, p&lt;0.05). FDG-avid ipsilateral hilar nodal involvement seen in 63%, mediastinal nodes in 70% while distant metastatic disease in 33%. Patients having primary lesion with SUVmax 20.0 and above were significantly associated with larger tumour size and FDG-avid ipsilateral hilar nodal uptake (p&lt;0.05). Conclusion: Lung SCC was intensely FDG-avid and had higher SUVmax compared to adenocarcinoma. Primary lesions with SUVmax 20.0 and above were associated with larger tumour size and presence of hypermetabolic ipsilateral hilar nodal spread. Information obtained from this review will provide valuable insight into PET-CT scan characteristics of newly diagnosed NSCLC cases in our institution that may influence not only scan reporting formulation but also patient management.International Journal of Human and Health Sciences Supplementary Issue 01: 2024 Page: S46

Abstract PO1-20-12: CD8+ Tumor Infiltrating Lymphocytes Turn a Cold Tumor Hot in Metastatic Breast Cancer

Abstract Introduction: Turning “cold” tumors “hot” is considered essential for immune-oncology therapies to be effective. Bria-IMT is an allogenic human cancer cell line with antigen presenting cell activity (SV-BR-1-GM) designed to overcome the immune-suppressive tumor microenvironment. However, until now there has not been proof that “cold” tumors can become “hot” with this therapy. Using Zr-89 crefmirlimab berdoxam, a zirconium-89 labelled truncated antibody specific to human CD8α and developed for CD8 ImmunoPET, we image before and after Bria-IMT therapy administration to assess the baseline status as well as changes in CD8 cell presence after initiation of therapy. Here we present the first evidence that cold tumors can become hot on treatment with Bria-IMT combined with an anti-PD-1 checkpoint inhibitor (CPI), showing CD8+ cells increased over baseline using CD8 ImmunoPET. Case: After informed consent, a 61 year-old Hispanic female, enrolled in the ongoing randomized phase 2 Bria-IMT trial in advanced heavily pretreated metastatic breast cancer (MBC) (NCT03328026). Her history included MBC in May 2020, ductal type, grade 3, triple negative breast cancer (TNBC) with 6 prior lines of therapy including a Trop-2-directed antibody-drug conjugate and 6 lines of chemotherapy. Precision medicine testing identified no actionable targets. All prior therapies had progressive disease as their best response. The subject was randomized to start the CPI after 2 cycles of Bria-IMT to “train” the host immune system before proceeding with combination immune-oncology therapy. Baseline testing revealed the subject to be anergic to candida and SV-BR-1-GM inoculation. However, by cycle 3 delayed-type hypersensitivity to SV-BR-1GM developed. Interestingly the subject matched SV-BR-1-GM at 2 HLA loci: DRB3*02:02 and DRB1*11:04 which in previous publications is associated with greater clinical benefit. Tumor markers were stable or decreased slightly including CEA (25% decrease) and CA 15-3 (43% decrease). Circulating Tumor Cells (CTCs) and Cancer Associated Macrophage Like cells (CAMLs) also improved. Standard imaging at baseline showed 3 main sites of disease including a large right breast mass, multiple right axillary lymph nodes and a right lower lobe mass with CD8 ImmunoPET uptake in these areas similar to the blood pool. On the follow-up CT imaging, all of these lesions increased in size with newly appreciated pulmonary nodules. The right lower lobe mass showed increased CD8 ImmunoPET accumulation with an SUV of 5.8 (close to the liver background) as compared to an SUV of 2.2 at baseline. The lesions in the right breast and right axilla remained at blood pool levels. There was an increase in CD8 ImmunoPET uptake in bilateral inguinal lymph nodes reaching an SUV of 4.8 as compared to SUV 2.2 at baseline. In addition, there were non-enlarged lymph nodes in bilateral axillary regions that also showed increased radio-tracer accumulation reaching an SUV of 9.5 as compared to SUV 4.9 at baseline. Conclusion: This subject demonstrated a mixed response of metastatic lesions on CD8 ImmunoPET with encouraging changes in peripheral blood tumor markers and CTCs. The nonspecific nodal localization of CD8 ImmunoPET may indicate a systemic activation of CD8 positive lymphoid cells. This shows the value of CD8 ImmunoPET in identifying lesions that are progressing on treatment versus pseudo progression. It also provides support that the Bria-IMT + CPI combination immune-based therapy can result in an increase of CD8+ tumor infiltrating lymphocytes in breast cancer metastatic sites as well as an increase in lymphoid organs. This advance may aid in triaging patients, adjudicating pseudo-progression and predicting clinical benefit of immune based therapies. Citation Format: Russ Kuker, Frances Valdes-Albini, Giuseppe Del Priore, Aazim Arif, Kristin Schmiedehausen, Carmen Calfa. CD8+ Tumor Infiltrating Lymphocytes Turn a Cold Tumor Hot in Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-20-12.

E032 Low dose methotextrate induced leukoencephalopathy: a case report

Abstract Background/Aims Methotextrate is a widely used disease modifying anti-rheumatic drug (DMARD) used to treat connective tissue disorder and inflammatory arthritis. Methotextrate induced neurological toxicity includes vomiting, headaches, blurred vision, mood alteration, somolescence, brain fog, hyperosmia, leukoencephalopathy and pseudo-stroke like syndrome. Here we report a case of methotextrate induced headache with leptomeningeal enhancement, which reversed after stopping the methotextrate. Methods A 66 year old male with known diagnosis of sero-positive rheumatoid arthritis with past medical history of Hodgkins lymphoma in remission. He started on dual DMARD combination of 15 mg methotextrate subcutaneously once a week and 200 mg hydroxychlroquin twice daily. Thereafter he reported history of headaches, which needed hospital admission. He underwent a CT-head scan on admission which did not show any acute concerns. The case was then discussed with the haematology team and later he underwent a PET scan of the whole body which was reviewed in Lymphoma MDT which showed non-specific uptake in hilar nodes, which does not significantly increase the suspicion of lymphoma relapse. On discharge he had MRI head contrast and MRV cerebral veins, which showed a few areas of irregular nodular curvilinear foci of predominantly meningeal enhancement noted in occipital lobes and adjacent T2 /flair hypertense signal noted in relation to these. These changes were discussed in neurology MDT, given the history of lymphomas a possibility, though rare in the absence of systemic relapse. The differential included low dose (oral) methotextrate related neurotoxicity. Patient was advised to stop methotextrate, they repeated MRI scan 3 weeks later which showed disappearance of the curvilinear lesions with leptomeningeal enhancement and patient reported headaches improved. Results List of investigations 1. CSF- profile, no protein, no growth 2. CSF PCR panel for Adeno/Paracheo/Entero/Varicella Zoster/HSV type 1&amp;2-negative 3. Histology report of CSF- No evidence of lymphoma 4. Neuronal Ab: Purkinje cell/ Hu Ab/Ri Ab amd Anti-amphiphysin Ab-negative 5. Myeloma screen- no paraprotein detected 6. Virus panel- EBV- IgM-, HIV /Hep B and C, Cytomegalovirus IgM-not detected. Conclusion Methotextrate is a potent anti-metabolite preventing the formation of tetrahydrofolate, and used as immunosuppressant and anti-neoplastic medication. Though the exact mechanism of the neurotoxicity is not known, the common hypothesis include; interference with myelin synthesis or maintenance and/or interference with neurotransmitter synthesis. The case reported here reiterates the importance of recognizing the neurological side effects in patients on methotextrate even on low dose of methotextrate. It also emphasizes the fact that the neurological changes are reversible on stopping methotextrate. Headaches can still be a side effect and might mimic stroke like episode in patients treated with low dose of subcutaneous methotextrate and hence stopping the medication should be considered in such cases. Disclosure P. Doddamani: None. A. Kinder: None.

Maximum PET/CT 18F-FDG uptake of lymph nodes predicts prognosis in esophageal squamous cell carcinoma

Maximum PET/CT 18F-FDG uptake of lymph nodes predicts prognosis in esophageal squamous cell carcinoma

Intraepithelial tumor-infiltrating lymphocytes shape loco-regional PET/CT spread of locally advanced cervical cancer

BackgroundData suggest an association between positron emission tomography/CT (PET/CT) metabolic metrics and tumor microenvironment in several malignancies, and a potential role of PET/CT to monitor response to immunotherapy.ObjectiveTo evaluate the...

A Cancer Nanovaccine for Co-Delivery of Peptide Neoantigens and Optimized Combinations of STING and TLR4 Agonists.

Immune checkpoint blockade (ICB) has revolutionized cancer treatment and led to complete and durable responses, but only for a minority of patients. Resistance to ICB can largely be attributed to insufficient number and/or function of antitumor CD8+ T cells in the tumor microenvironment. Neoantigen targeted cancer vaccines can activate and expand the antitumor T cell repertoire, but historically, clinical responses have been poor because immunity against peptide antigens is typically weak, resulting in insufficient activation of CD8+ cytotoxic T cells. Herein, we describe a nanoparticle vaccine platform that can overcome these barriers in several ways. First, the vaccine can be reproducibly formulated using a scalable confined impingement jet mixing method to coload a variety of physicochemically diverse peptide antigens and multiple vaccine adjuvants into pH-responsive, vesicular nanoparticles that are monodisperse and less than 100 nm in diameter. Using this approach, we encapsulated synergistically acting adjuvants, cGAMP and monophosphoryl lipid A (MPLA), into the nanocarrier to induce a robust and tailored innate immune response that increased peptide antigen immunogenicity. We found that incorporating both adjuvants into the nanovaccine synergistically enhanced expression of dendritic cell costimulatory markers, pro-inflammatory cytokine secretion, and peptide antigen cross-presentation. Additionally, the nanoparticle delivery increased lymph node accumulation and uptake of peptide antigen by dendritic cells in the draining lymph node. Consequently, nanoparticle codelivery of peptide antigen, cGAMP, and MPLA enhanced the antigen-specific CD8+ T cell response and delayed tumor growth in several mouse models. Finally, the nanoparticle platform improved the efficacy of ICB immunotherapy in a murine colon carcinoma model. This work establishes a versatile nanoparticle vaccine platform for codelivery of peptide neoantigens and synergistic adjuvants to enhance responses to cancer vaccines.

Identifying Functional Lymph Nodes in Lower Extremity Lymphedema Patients: The Role of High-frequency Ultrasound.

Lymph nodes may play a potential role in lymphedema surgery. Radiologic evaluation of nodes may reveal the status of pathologic conditions but with limited accuracy. This study is the first to evaluate the efficacy of ultrasound in detecting functioning nodes in lymphedema patients and presents a criterion for determining the functionality of the lymph nodes. This retrospective study reviews 30 lower extremity lymphedema cases which were candidates for lymph node to vein anastomosis. Lymphoscintigraphy and magnetic resonant lymphangiography (MRL) imaging were compared with ultrasound features which were correlated to intraoperative indocyanine green (ICG) nodal uptake as an indication of functionality. Majority were International Society of Lymphology stage 2 late (50.0%) and stage 3 (26.7%). ICG positive uptake (functioning nodes) was noted in 22 (73.3%), while 8 patients (26.6%) had negative uptake (nonfunctioning). Ultrasound had significantly the highest specificity (100%) for identifying functional nodes followed by lymphoscintigraphy (55%) and MRL (36%; p = 0.002, p < 0.001, respectively). This was associated with 100% positive predictive value compared against lymphoscintigraphy (44%) and MRL (36%; p < 0.001 for both). The identified ultrasound imaging criteria for functioning lymph node were oval lymph node shape (Solbiati Index), morphology, vascularity pattern, and vascularity quantification. The use of ultrasound in nodal evaluation was proven effective in different pathologic conditions and demonstrated the best prediction for functionality of the lymph node based on the new evaluation criteria.

Hypermetabolic Axillary Lymphadenopathy After Shingrix Vaccination for Varicella Zoster Virus.

A 67-year-old woman underwent staging 18 F-FDG PET/CT scan for recently diagnosed breast cancer. Her scan showed a highly hypermetabolic right breast mass, with ipsilateral hypermetabolic axillary lymph nodes. The contralateral axillary lymph nodes were also enlarged with avid FDG uptake, alongside focal increased uptake in the left deltoid muscle. Upon investigation, the patient reported receiving the new zoster recombinant adjuvanted varicella zoster vaccine (Shingrix, GlaxoSmithKline) 4 days before the scan. The lymph node uptake could be potential pitfall for cancer staging.