Radioactive Uptake Research Articles

Site-Specific Modification of Native IgGs with Flexible Drug-Load.

Homogeneous, site-specifically conjugated antibodies have shown to result in antibody-drug conjugates (ADCs) with improved efficacy and tolerability compared to stochastically conjugated ADCs. However, precisely controlling the drug load as well as attaching multiple payload moieties to the antibody remains challenging. Here, we demonstrate the simple and direct modification of native IgG-antibodies at the residue glutamine 295 (Q295) without the need for any protein engineering with flexible drug-to-antibody ratios of one or multiple payloads. The conjugation is enabled through short, positively charged lysine containing peptides and native, commercially available microbial transglutaminase. In proof-of-concept studies, HER2-targeting ADCs based on trastuzumab were generated with drug-to-antibody ratios (DARs) of 2 and 4 of the same or different payloads using orthogonal conjugation chemistries. Quantitative biodistribution studies performed with 111In-radiolabeled conjugates showed high tumour uptake and low accumulation of radioactivity in non-targeted tissues. A single dose study of trastuzumab conjugated to the highly potent payload α-Amanitin demonstrated complete and long-lasting tumour remission and was well-tolerated at all dose levels tested.

Immuno-PET Imaging of EGFR with 64Cu-NOTA Panitumumab in Subcutaneous and Metastatic Nonsmall Cell Lung Cancer Xenografts.

Objective: About 65-90% of nonsmall cell lung cancer (NSCLC) express the epithelial growth factor receptor (EGFR) as a transmembrane protein that is activated by binding of specific ligands, including epidermal growth factor and transforming growth factor α (TGFα). Identifying EGFR as an oncogene has led to the development of anticancer therapeutics directed against EGFR, including the full-length human IgG2 monoclonal antibody panitumumab. The main goal of the present study was to investigate 64Cu-labeled panitumumab with immuno-PET in subcutaneous and metastatic EGFR-positive NSCLC xenografts. Methods: Bifunctional chelating agent 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclo-nonane-1,4,7-triacetic acid (NOTA-NCS) was attached to panitumumab. The number of chelators per panitumumab was determined using matrix-assisted laser desorption/ionization (MALDI) mass spectroscopy. The incorporation efficiency of 64Cu into NOTA-panitumumab was measured by using radio-TLC. EGFR-expressing epithelial-like H1299-luc+ NSCLC cells were used for in vitro and in vivo experiments. Cell uptake of [64Cu]Cu-NOTA-panitumumab was measured in the presence and absence of panitumumab. Subcutaneous and metastatic H1299-luc tumor models were grown in male NSG mice. The presence of tumors at lung and metastatic sites was analyzed by [18F]FLT PET. Immuno-PET with [64Cu]Cu-NOTA-panitumumab was performed as static PET imaging at 2, 24, and 48 h postinjection in both tumor models. Proof-of-target was confirmed by blocking experiments with panitumumab. Detailed ex vivo biodistribution experiments were performed in both animal tumor models to confirm biodistribution profiles obtained by immuno-PET imaging. Results: MALDI analysis confirmed the attachment of ∼1.5 NOTA per antibody. Radiolabeling efficiency with [64Cu]CuCl2 was 93.8 ± 5.7% and a molar activity of 0.65 MBq/μg. Cellular uptake studies with [64Cu]Cu-NOTA-panitumumab in H1299 cells demonstrated increasing uptake over time, reaching 29.1 ± 2.9% radioactivity(Bq)/mg protein (n = 3) and plateauing at 45 min. Addition of 25 μg of panitumumab reduced radioligand uptake to 1.22 ± 0.06% radioactivity/mg protein (n = 3). PET imaging revealed high uptake of [64Cu]Cu-NOTA-panitumumab in subcutaneous tumors: Standardized uptake values (SUV)mean reached 4.70 ± 0.42 and 5.37 ± 0.40 (n = 5) after 24 and 48 h postinjection, respectively. Administration of 1 mg panitumumab reduced tumor uptake significantly to 1.94 ± 0.22 and 1.66 ± 0.08 (n = 4; p < 0.001). In the metastatic model, the following SUVmean were analyzed from liver and lung lesions: 5.55 ± 0.34 and 6.28 ± 0.46 (both n = 23 lesions from 6 mice) after 24 and 48 h postinjection, which was also significantly reduced to 2.53 ± 0.39 and 2.31 ± 0.15 (both n = 16 lesions from 4 mice; p < 0.001) after injection of 1 mg panitumumab. Detailed ex vivo biodistribution confirmed immuno-PET analysis in both models. Panitumumab reduced radioactivity uptake into subcutaneous tumors from 11.01 ± 0.72 (n = 4) to 3.67 ± 0.33% ID/g (n = 5; p < 0.001), and in metastatic liver lesions from 29.44 ± 8.14 (n = 4) to 8.35 ± 1.30% ID/g (n = 5; p < 0.001), respectively. Conclusions: [64Cu]Cu-NOTA-panitumumab was successfully used for immuno-PET imaging of EGFR-expressing subcutaneous and metastatic NSCLC tumors. This result represents the basis for developing radiotheranostics for targeting EGFR in cancers and for selecting the right patients for the right treatment at the right time.

[18F]TFB PET/CT misses intense [124I]iodine-avid metastases after redifferentiation therapy in metastatic thyroid cancer

BackgroundFluorine 18-labelled tetrafluoroborate ([18F]TFB) is a substrate for the sodium/iodide symporter. In thyroid cancer, [18F]TFB-PET/CT may be an alternative to iodine imaging to evaluate the extent of disease, eligibility for radioiodine treatment, and success of redifferentiation therapies. We report the results of a pilot study to determine tumor uptake of [18F]TFB and compare its properties to [124I]IodinePET/CT in patients with metastatic thyroid cancer.MethodsFive patients were included in a prospective study. All patients received PET/CT 1 h after injection of 356 ± 12 MBq [18F]TFB and were given 230 ± 9 MBq [124I]Iodine orally on the same day, followed by PET/CT after 48 h. Before redifferentiation therapy, patients underwent an additional baseline [124I]Iodine PET/CT. Cases were analyzed by two board-certified specialists. Detection rates and Spearman correlation for [18F]TFB and [124I]Iodine were calculated.ResultsThree patients had poorly differentiated thyroid cancer and received trametinib in a redifferentiation trial. Two patients had papillary thyroid cancer and did not receive redifferentiation therapy. Of the 33 lesions seen before/without redifferentiation therapy, 19 (58%) were visible on [18F]TFB and 30 (91%) on [124I]Iodine imaging. In the patients who underwent redifferentiation therapy, 48 lesions were newly seen on [124I]Iodine PET/CT with a median SUVmax of 3.3 (range, 0.4–285.0). All of these lesions were [18F]TFB-negative.Conclusion[18F]TFB failed to predict radioactive iodine uptake in patients with poorly differentiated thyroid cancer who underwent redifferentiation therapy with trametinib. It is unclear whether such discrepancies may also occur in other redifferentiation therapies or may even be encountered in redifferentiation-naïve thyroid cancer.Trial registration numberNCT03196518, registered on June 22, 2017.

6601 A Case of Recurrent Painless Thyroiditis and Discussion of Management

Abstract Disclosure: M.C. Slack: None. S. Grock: None. Introduction: Painless (silent) thyroiditis is characterized as a subacute and generally self-limited disease process in which patients develop transient thyrotoxicosis, which is often followed by a hypothyroid phase before entering the recovery euthyroid phase. Given high frequency of positive thyroid antibodies, it may be autoimmune-mediated; recurrence is rare. Here we present a case of recurrent painless thyroiditis and discuss management options. Clinical Case: A Korean woman was followed by endocrinology from age 38 to 60 and experienced at least seven episodes of painless thyroiditis over this time. The episodes occurred without an identifiable trigger and were not preceded by viral illness. During episodes she developed palpitations, hair loss, and dyspnea on exertion and biochemical evidence of thyrotoxicosis with TSH suppressed to &amp;lt;0.2 mIU/mL (normal 0.3-4.7) and elevated free T4 levels as high as 5.4 ng/dL (normal 0.8-1.7). TSI, TPO, and TSH receptor antibodies were checked during multiple episodes and resulted negative, though thyroglobulin antibody was significantly elevated. A radioactive iodine uptake scan was obtained during an active episode of thyroiditis and revealed diffusely low uptake. The patient’s episodes lasted approximately two to three months before normalization of her TSH and FT4. She had at least one instance of transient hypothyroidism after thyrotoxicosis with a TSH of 13.2 and FT4 of 0.6 which subsequently normalized 6 weeks later. The patient did not have known cardiovascular disease and DXA scans revealed mild osteopenia with the lowest T-score -1.3. RAI was considered for the patient based on the total number and increasing frequency of her episodes. She ultimately declined treatment with RAI and continues to follow with endocrinology. Clinical Lessons: While the deleterious effects of prolonged hyperthyroidism (e.g. osteoporosis, arrhythmia, cardiovascular disease) are well known, it is unclear what risk recurrent painless thyroiditis episodes pose. As there are no guidelines regarding treatment, clinical gestalt incorporating frequency and duration of episodes, as well as symptoms, is often used to determine if definitive management is indicated. There are case reports in the literature of treatment of recurrent thyroiditis with RAI ablation performed during a euthyroid state, which eliminated recurrence of episodes but did lead to permanent hypothyroidism necessitating hormone replacement. Surgical thyroidectomy may also be considered in select patients. This case highlights the challenges in treating rare cases of recurrent painless thyroiditis given the lack of research or established guidelines. It is reasonable to consider the frequency, severity, and total number of episodes, as well as patient risk factors, symptoms, and preferences when making recommendations regarding management. Presentation: 6/1/2024

9188 Hashitoxicosis To Graves': A Case Of Fluctuating Thyroid Autoimmunity Induced By The Covid Vaccine

Abstract Disclosure: K. Lamar: None. N. Meda: None. J. Straughan: None. D. John: None. S.K. Suryanarayanan: None. Introduction: Thyroid antibodies are essential for identifying autoimmune thyroid disease. In Graves' disease thyroid stimulating immunoglobulin (TSI) is crucial to diagnosing, guiding treatment, and determining prognosis for ophthalmopathy; thyroid peroxidase (TPO) antibody is likewise crucial in the diagnosis of Hashimoto’s Thyroiditis. Conversion between these two diseases is extremely rare. Case: The patient is a 60-year-old female with a medical history of hypertension, asthma, T2NxM0 low grade gastrointestinal stromal tumor (GIST), and hyperaldosteronism who was referred to the endocrine clinic for “thyroid disorders'' with symptoms including weight gain and palpitations. Her labs showed thyroid stimulating hormone (TSH) &amp;lt;0.01mIU/L, free Triiodothyronine (fT3) 6.5ng/mL, free Thyroxine (fT4) 1.6ng/dL, TPO antibodies 46IU/mL, negative TSI antibodies 102%, and a negative Thyroglobulin antibody (Tg Ab) &amp;lt;1IU/mL. A slightly enlarged thyroid was noted on ultrasound. Radioactive iodine uptake (RAI) was normal with 15% uptake at 6 hours and 25% at 24 hours. These findings led to the diagnosis of Hashimoto thyrotoxicosis. She started methimazole 10mg and atenolol 50mg. One year later, she received the Pfizer mRNA COVID-19 vaccine and had her GIST tumor resected. She then began switching between hyper-, hypo-, and euthyroid states with multiple titrations of her Methimazole dose. Repeat testing demonstrated a positive TPO 41 IU/mL, negative Tg Ab &amp;lt;1, positive TSI 294%, and positive RAI with 47% uptake at 6 hours and 61% at 24 hours, consistent with Graves’ disease. It was found that even minor titration by 2.5mg in her Methimazole led to profound changes in her thyroid laboratory values and symptoms. She underwent total thyroidectomy and was started on levothyroxine with significant improvement. Discussion: This patient initially presented with antibodies as well as low uptake on the radio-iodine scan indicating her state of hyperthyroidism was due to Hashitoxicosis, but then later these tests were repeated and were more indicative of Grave’s disease. This was possibly due to immune challenges in the patient, assay inter-variability of thyroid autoantibodies, or an effect of the patient receiving the COVID vaccine. The phenomenon of TSI antibodies converting from negative to positive has not been well documented previously. The goal of this case was to report an interesting conversion of Grave’s disease identifying antibodies and the importance of evaluating underlying immune challenges which could play a role in altering clinical disease. Presentation: 6/1/2024

6770 Graves’ disease induced by COVID-19 infection in a 49 year old male

Abstract Disclosure: N. Al-hosainat: None. A. Al Najada: None. T. Salar: None. S. Iqbal: None. K. Abdel Gadir: None. Introduction: Graves’ disease is an autoimmune disease causing hyperthyroidism, characterized by elevated thyrotropin-receptor antibodies. COVID-19 infection has been increasingly reported as a trigger of thyroid illness including Graves’ disease. We present a unique case of 49-year-old patient who was diagnosed with Graves’ disease after COVID-19 infection. Case description: A 49-year-old male patient with history of prediabetes presented with complaints of tremor, fatigue, generalized itching, and unintentional weight loss (30 Ibs in 6 months). He had COVID-19 infection 3 months prior. The remainder of review of systems was negative. No family history of thyroid disease. On exam, the patient had sinus tachycardia with otherwise normal vital signs. Diffuse thyromegaly was noted along with an intermittent fine tremor of the extremities. Blood work was notable for low TSH &amp;lt;0.01 uIU/mL, elevated free T4 (3.4 ng/dL), free T3 (17.6ng/dL), and TSH receptor antibody (12 IU/L). Thyroid ultrasound showed mild goiter with 2 nodules, one of which was TIRADS 4 and 1.5cm. This nodule was biopsied and found to be benign. Radioactive iodine uptake scan revealed homogeneous diffuse increased thyroid uptake. The diagnosis of Graves’ disease was made, and the patient was started on propranolol and methimazole with significant improvement of his symptoms and his laboratory tests normalizing. Discussion: Graves' disease is an autoimmune disease, characterized by hyperthyroidism, goiter, occasional orbitopathy and dermopathy. Caused by antibodies against thyroid-stimulating hormone receptors which stimulate thyroid hormone secretion and thyroid growth. Treatment is aimed to decrease thyroid hormone synthesis by either a Thionamide, radioiodine ablation, or surgery. Remission rates with antithyroid drugs average under 40 percent after one to two years of treatment and could exceed 80 percent after 5 to 10 years of treatment. COVID-19 is a multi-system disease, caused by SARS-CoV-2 virus, transmitted by large droplets and small particle aerosols, was declared a pandemic in 2020 and affected millions of people worldwide. There is emerging data showing the association of COVID-19 with various thyroid diseases including thyroiditis and relapse of known Graves' disease after the infection. We present a case of newly diagnosed Graves’ disease after COVID-19 infection in a patient with no personal or family history of such disease which raises the concern of autoimmune pathway activation induced by the infection. The onset of Graves’ disease after COVID-19 infection does not depend on the presence of pre-existing thyroid pathology and in this case responded well to antithyroid medication. Conclusion: COVID-19 can lead to the development of a range of medical illnesses. In patients who develop symptoms of thyrotoxicosis, Graves’ disease should be suspected, investigated, and treated appropriately Presentation: 6/3/2024

8791 A Case of Hyperfunctioning Thyroid Nodules Evaluated for Thyroid Metastasis in the Setting of Oropharyngeal Squamous Cell Carcinoma

Abstract Disclosure: M. Alashoor: None. J. Gogineni: None. A. Bakar: None. Introduction: Identifying and evaluating hyperfunctioning thyroid nodules in the setting of metastatic head and neck cancers represents a diagnostic challenge that may result in inaccurate identification of perithyroidal lymph node metastasis as malignant or metastatic thyroid nodules with standard workup. Case presentation: A 72-year-old male with a history of stage IV metastatic oropharyngeal squamous cell carcinoma, metastasized to the lymph nodes, lungs, mediastinum, and bilateral iliac bones. He was diagnosed two years ago and received chemotherapy, maintenance immunotherapy with pembrolizumab, and targeted palliative radiation therapy, with good clinical response. Restaging PET-CT two years later revealed local progression. During his workup, he was noted to have persistently abnormal thyroid function test with low TSH (0.03​​µIU/mL, n 0.3-5.33), normal free T4 (0.97ng/dL, n 0.60 - 1.40), mildly elevated free T3 (3.91pg/mL, n 2.5-3.9), negative thyrotropin receptor antibodies levels, negative TSI, negative TPO antibody, noted evidence of subclinical hyperthyroidism consistent over the past year. Radioactive iodine uptake demonstrated multinodular gland, mildly elevated 24-hour uptake of 28% consistent with hyperthyroidism, with decreased activity in the left lobe. Thyroid ultrasound revealed multiple probable malignant thyroid nodules, a 1.8 cm TI-RADS 5 lesion of the deep margin of the lower pole of the right lobe, and a 1.6 cm TI-RADS 5 lesion of the upper pole on the right lobe. He was treated with methimazole 5 mg. Further workup with fine needle aspiration demonstrated the right upper lobe nodule sample was positive for squamous cell carcinoma, findings suspicious for metastasis. He subsequently proceeded with radical tonsillectomy, right neck dissection, and right hemithyroidectomy. Surgical pathology results noted, right neck metastatic HPV-associated squamous cell carcinoma involving the lymph nodes with extranodal extension, right oropharyngeal HPV-mediated squamous cell carcinoma. The thyroid gland biopsy was significant for incidental papillary microcarcinoma 2mm, thyroid follicular nodular disease, without evidence of squamous cell carcinoma or metastatic infiltration. Post-hemithyroidectomy, his thyroid function normalized, and methimazole was discontinued. Conclusion: Thyroid metastasis from head and neck cancers represent a rare entity. In patients with a history of malignancy, evaluation of new thyroid masses remains crucial. While FNA is a sensitive method for detecting thyroid metastases, inaccuracies may occur, impacting the identification of thyroid nodules in the presence of local metastatic lymphadenopathy. Identifying squamous cell carcinoma in the thyroid can significantly influence the treatment plan of patients with metastatic carcinomas, therefore careful consideration must be undertaken on evaluation. Presentation: 6/1/2024

7314 The Thyroid Tetralogy: Hypothyroidism, Graves' Disease, AFTN, and Thyroid Cancer in a Single Patient

Abstract Disclosure: F. Sajid: None. F. Mohammadrezaei: None. K. Tiwari: None. J. Shapiro: None. F. Mohsin: None. T. Lin: None. Introduction: In this case, we explore a rare and complex situation involving a patient's shift from hypothyroidism to hyperthyroidism. This transition led to the diagnosis of Marine Lenhart Syndrome (MLS), an uncommon condition characterized by the coexistence of Graves' disease and autonomously functioning thyroid nodules (AFTNs). Adding to the complexity of the case, the patient was also diagnosed with papillary thyroid carcinoma (PTC). Case Presentation: A 47-year-old woman with a history of hypothyroidism, treated with levothyroxine for 14 years, presented with palpitations, weight loss, and insomnia for a few months. Her levothyroxine dose was gradually reduced and eventually discontinued by her primary care physician due to low TSH and high free T4 levels. Post-discontinuation, her symptoms were improving. Laboratory tests showed TSH 0.01 mIU/mL (0.39-4.08), Thyroglobulin (TG) 72 ng/mL (3-40), Free T4 2.5 ng/dL (0.8-1.8), Free T3 11.5 ng/dL (0.2-0.5ng/dL). Furthermore, Thyrotropin Receptor Antibody (TRAb), and Thyroid Peroxidase Antibody (TPO Ab) were positive leading to a diagnosis of Graves' Disease and initiation of Methimazole. After three months on Methimazole, her TSH remained suppressed with normalized free T4 and T3 levels. A thyroid ultrasound revealed bilateral nodules, with a calcified well-circumscribed nodule in the right mid-pole. A Radioactive iodine uptake (RAIU) scan showed a hyperfunctioning right mid-pole thyroid nodule. Fine-needle aspiration biopsy was consistent with Bethesda V, suggestive of possible malignancy. Consequently, she underwent a total thyroidectomy, with pathology confirming multifocal classic PTC, stage pT1bN0. Post-surgery, she developed hypothyroidism and was started on levothyroxine. Four weeks later, her TSH remain suppressed, other thyroid function tests and calcium levels were within normal range: TSH 0.01 mIU/mL, Free T4 1.0 ng/dL, TG 4.6 ng/mL, Thyroglobulin antibodies 1 IU/mL (less than or equal to 1), PTH intact 43 pg/mL (16-77), and Calcium 8.9 mg/dL (8.6-10.2). Conclusion: This case represents a complex and unusual medical scenario where a patient transitioned from hypothyroidism to hyperthyroidism, ultimately leading to the diagnosis of MLS in conjunction with PTC. The exact mechanism behind this transition is not fully understood. In the management of hypothyroidism, adjustments in thyroxine dosage are common, but significant tapering of the dose should prompt further investigation. The presence of PTC in AFTNs is considered rare, as AFTNs are typically characterized as hot nodules, implying they are hyperfunctioning and generally considered to be less likely malignant compared to cold nodules. This case underscores the need for comprehensive evaluation and follow-up in patients with thyroid disorders, especially when there is a change in thyroid function or the presence of nodules. Presentation: 6/3/2024

8288 Navigating Diagnostic Challenges of Amiodarone Induced Thyrotoxicosis in a Psychiatrically Complex Patient within a Community Hospital Setting

Abstract Disclosure: M.S. Shah: None. K.P. Sanu: None. S. Humayon: None. R. Chawla: None. N.K. Bains: None. This case delves into the intricate diagnostic and therapeutic journey of a 64-year-old male who presented to a community hospital with psychosis. Medical history was pertinent for ventricular arrhythmias treated with amiodarone 400 mg once daily, bipolar disorder with medication non-compliance and heart failure with reduced ejection fraction status post automatic implantable cardioverter-defibrillator placement. Collaboration with the patient's family revealed a history of repeated hospitalizations for similar presentations as well as recent weight loss. The challenge lay in distinguishing between manic episodes and other potential underlying medical causes. The patient's recent weight loss and amiodarone use prompted a thyroid panel, revealing a TSH of 0.01 mlU/L (n = 0.27 to 4.20 mIU/L), free T4 of &amp;gt;7.77ng/dL (n = 0.93 to 1.70 ng/dL), and free T3 of &amp;gt;7.51ng/dL (n = 2.00 to 4.40 pg/mL). Inadequate facilities for a radioactive iodine uptake (RAIU) scan and thyroid doppler ultrasound heightened the diagnostic challenge, making the history and physical exam pivotal in steering the course of this patient's care. The Burch-Wartofsky score was found to be elevated at 30 due to delirium and abdominal pain reported in the emergency department. Amiodarone use for over two years with no prior history of thyroid dysfunction, along with the absence of a goiter or thyroid antibodies suggestive of Graves disease heightened the suspicion for amiodarone-induced thyrotoxicosis type 2 (AIT type 2). Due to the lack of RAIU scan and thyroid ultrasound to better differentiate between AIT type 1 and type 2, the patient was treated with methimazole and prednisone along with an antipsychotic medication regimen. The discontinuation of antipsychotic medications became necessary due to QTc prolongation and subsequent defibrillator discharge. The patient's further improvement without psychiatric medications highlighted the success of the tailored treatment strategy, emphasizing the importance of accurate diagnosis in patients with psychiatric comorbidities. The patient’s relatively rapid clinical response also aids in differentiating AIT type 1 from type 2. This case brings awareness to the importance of a comprehensive history and physical exam, particularly in the setting of a community hospital with limited diagnostic resources. Despite the inability to obtain history directly from the patient and having diagnostic constraints, the judicious use of available resources and clinical acumen led to the diagnosis of Amiodarone-induced thyrotoxicosis type 2. Clinicians should keep a broad differential to avoid confirmation bias in treating psychiatric patients with a complex medical history. This case serves as a testament to the importance of a holistic approach to patient care and the need for ongoing advancements in diagnostic capabilities within community healthcare settings. Presentation: 6/2/2024

8135 A Rare Case of Late Recurrence of Graves’ Disease Decades After Radioactive Iodine Therapy: Is it Really a Definitive Treatment?

Abstract Disclosure: K.S. Hill: None. R. Osman: None. Graves’ disease (GD) is the most common cause of hyperthyroidism in the US and worldwide. Radioactive iodine (RAI) therapy has excellent success rates in treatment of GD. Studies have demonstrated that RAI successfully treats GD with a single session in the majority of cases. Recurrence after RAI, if it occurs, is most commonly seen in the first year after RAI. However, this is rare particularly in patients who have developed evidence of successful treatment in the form of post-ablative hypothyroidism. Only a few case reports have demonstrated recurrence of GD more than 10 years after treatment of GD with RAI and development of post-ablative hypothyroidism. We report a case of GD recurrence approximately 30 years after ablation. A 69 y/o woman presented for evaluation of hyperthyroidism and newly discovered thyroid nodule. Her history was significant for GD with orbitopathy diagnosed in the early 1990s and treated with RAI. Following the ablation, she developed hypothyroidism and was managed for over 20 years on levothyroxine therapy. In recent years she began to develop symptoms of palpitations and heat intolerance with biochemical evidence of thyrotoxicosis despite reductions in her levothyroxine dose. She also developed recurrence of her orbitopathy, confirmed by ophthalmology. During this time, a neck CT incidentally described an atrophic thyroid gland with a 9 mm soft tissue nodule in the left thyroid bed. Follow up ultrasound showed a 1.1 cm nodule with increased vascularity in the left thyroid bed with an otherwise atrophic gland and no lymphadenopathy. Her levothyroxine was stopped for one month in preparation for a thyroid uptake scan, during which TSH increased to 15 mcU/mL. Scan showed overall severely decreased radioactive iodine uptake of the gland consistent with prior ablation although there was a faint uptake most focally conspicuous on the left side inferiorly. Thyroid stimulating immunoglobulin (TSI) was elevated at 1.35 IU/L (Ref 0.00-0.55). After discussion with the patient, the decision was made for surgical treatment with thyroidectomy. Pathology was benign. She was continued on her prior dose of levothyroxine 75 mcg daily however now with clinical and biochemical evidence of hypothyroidism requiring continued increase in levothyroxine dose to normalize TSH levels. GD is the most common cause of hyperthyroidism and RAI therapy is the most common definitive treatment for GD in the US. Recurrence of GD after ablative hypothyroidism is rare, particularly in the case of late recurrence decades after ablation. Only a few cases are reported in the literature, ours with the longest interval-to-relapse. Recurrence of orbitopathy may be the first clue. Our case highlights the need to continue to monitor clinically for recurrence of Graves’ disease long after RAI use. Presentation: 6/3/2024

8105 Radiation-Induced Hyperthyroidism in the Context of Palliative Radiation Therapy

Abstract Disclosure: A. Randhawa: None. G. Palaguachi: None. J.G. Karam: None. Introduction: Palliative radiotherapy, designed to alleviate focal symptoms in advanced, incurable cancer, aims to enhance quality of life with minimal treatment burden. The thyroid gland's susceptibility to neck radiation is known, primarily leading to hypothyroidism. However, hyperthyroidism is a much less frequently reported adverse effect that is poorly understood. This case report highlights an unusual instance of radiation-induced hyperthyroidism. Case Presentation:The patient is a 53 years-old woman with history of Ewing’s sarcoma of the sacrum diagnosed in August 2022, treated initially with chemotherapy (cyclophosphamide, vincristine, etoposide and ifosfamide), but diagnosed with leptomeningeal metastasis and T12/L1 mass in October 2023 when she presented with lower extremities weakness and urinary incontinence. She underwent T12-L1 laminectomy, resection of tumor and fusion, and was started on palliative intent radiation therapy for the brain and C-spine. A month later, she was admitted for altered mental status and was found to be persistently tachycardic at 140 bpm. Thyroid function testing was sent and revealed hyperthyroidism with TSH of 0.07 mIU/L (0.39-4.08), Free T4 of 1.74 ng/dl (0.58-1.64), T4 of 10.7ug/ml (4.4-9.5), T3 of 0.54 ng/ml (0.72-1.35), with undetectable Thyroid Peroxidase Antibodies and Thyroid Stimulating Immunoglobulin level. Thyroid Ultrasound showed a small and homogenous thyroid gland with no discrete nodules. Radioactive Iodine uptake and scan was not obtained because of exposure to iodized contrast during hospital stay. The patient had no available baseline thyroid function tests. She had no recent fever or viral illness. Unfortunately, her clinical condition deteriorated rapidly, and she passed away on the seventh day of admission. Conclusion: While hypothyroidism is a well-established consequence of high-dose irradiation, the mechanisms behind the rarer radiation-induced hyperthyroidism remain unclear. Speculation includes the release of autoantigens from damaged thyroid glands, triggering an immune response and potentially leading to Graves' hyperthyroidism. However, our case more likely represents a hyperthyroid phase in the triphasic sequence of destructive subacute thyroiditis, given the absence of elevated thyroid antibodies, thyroid nodules, and other causes of thyroiditis. Increasing awareness of radiation-induced hyperthyroidism, unraveling its mechanisms, and refining diagnostic strategies such as obtaining baseline and monitoring thyroid function testing are crucial, particularly in the context of palliative therapy, where striking the delicate balance between efficacy and minimizing toxicity is paramount. Presentation: 6/3/2024

Association of COVID-19 with thyroid dysfunction and autoimmune thyroid disease: A retrospective cohort study

BackgroundSince the end of the COVID-19 pandemic, the potential roles of thyroid-inflammatory derangements in driving or being associated with the prognosis of COVID-19 remain controversial. We aimed to clarify the association between COVID-19 infection and thyroid dysfunction, and highlight the impacts of subsequent autoimmune thyroid disease (AITD) on the prognosis of COVID-19. MethodsThe retrospective, multicenter, cohort study enrolled 2,339 participants with COVID-19 from three hospitals located in the north, middle, and south regions of Shaan Xi Province, China, between December 2022 and July 2023. 464 non-COVID-19 patients within the same period were supplemented, divided into groups with and without AITD. At hospital admission (baseline), 3- and 6-month follow-ups, we presented a dynamic description and correlation analysis of thyroid-inflammatory-autoimmune derangements in patients with AITD. ResultsA total of 2,082 COVID-19 patients diagnosed with AITD and 257 cases without AITD were included in the study, and 464 non-COVID-19 patients were supplemented, dividing into 14 AITD and 450 non-AITD cases. We found that COVID-19 infection was closely associated with thyroid dysfunction (χ2 = 1518.129, p = 0.000). AITD patients with COVID-19 showed a higher prevalence of symptoms and comorbidities and longer hospital stays at baseline than non-AITD patients with COVID-19 (p = 0.000, p = 0.000, and p = 0.000). The baseline free triiodothyronine (FT3), free thyroxine, and radioactive iodine uptake at 24 h in AITD cases significantly decreased (p = 0.000, p = 0.000, and p = 0.000), while thyroid stimulating hormone, thyroglobulin, reverse triiodothyronine (rT3), and thyroid antibodies varying elevated from the baseline to the follow-up (baseline: p = 0.000, p = 0.000, p = 0.000, p = 0.000, p = 0.000, and p = 0.000; 3-month follow-up: p = 0.000, p = 0.000, p = 0.000, p = 0.000, p = 0.030, and p = 0.000). C-reactive protein, calcitonin, interleukin-6, -8, -10, and tumor necrosis factor-α rose significantly at baseline (p = 0.000, p = 0.000, p = 0.000, p = 0.000, p = 0.000, and p = 0.000) in AITD. Interferon-α and interferon-γ at baseline showed a significant decrease (p = 0.000 and p = 0.000), and remained at low levels after 6 months (p = 0.000 and p = 0.000). FT3 and rT3 were positively and negatively correlated with hospitalization, respectively (r = -0.208 and 0.231; p = 0.000 and p = 0.000). ROC curves showed that FT3 and rT3 had better robustness in predicting severe COVID-19 prognosis (AUC = 0.801 and 0.705). Ordered logistic regression revealed that ORs were 0.370, 0.048, and 0.021 for AITD [(subacute thyroiditis, Grave's disease, and Hashimoto's thyroiditis compared to non-thyroidal illness syndrome (NTIS)] with COVID-19 risk, indicating that NTIS was the predominant risk factor for the severity of COVID-19. ConclusionsA robust association has been identified, wherein COVID-19 infection is closely associated with thyroid dysfunction, and the subsequent AITD may aggravate the poor prognosis of COVID-19.

Le cancer thyroïdien différencié réfractaire à l’iode : quelle prise en charge en 2024 ?

TREATING RADIO-IODINE REFRACTORY DIFFERENTIATED THYROID CANCER IN 2024: About 5 to 10% of patients with differentiated thyroid cancer (DTC) have advanced tumors at presentation or recurrence, with invasive cervical disease and/or distant metastases that cannot be effectively treated by conventional treatment, i.e. thyroid surgery and radioactive iodine. These DTC cases are defined as refractory to radioiodine (RAIR) and require expert multidisciplinary management. In France, patients are referred to centers of the ENDOCAN-TUTHYREF Network. This review summarizes current management of RAIR DTC patients and therapeutic options available in 2024. We discuss following topics : epidemiological data, modalities of local ablative treatment for selected metastatic lesions, molecular tests to be performed, optimum timing for initiating systemic therapy, choice of first-line treatment among validated tyrosine kinase inhibitors (TKIs), alternative targeted treatments (including selective TKIs adapted to the molecular profile, some of which can redifferentiate and restore radioactive iodine uptake), proactive management of TKI side effects, and finally give an overview of systemic strategies. Management of RAIR DTC is still challenging but substantial progress has been made over the last decade that has significantly improved outcome for these more aggressive thyroid cancer.

Zirconium- 89 Labeled Antibody K1-70 for PET Imaging of Thyroid-stimulating Hormone Receptor Expression in Thyroid Cancer.

Thyroid-stimulating hormone receptor (TSHR) is a G-protein coupled receptor that is highly expressed on benign and malignant thyroid tissues. TSHR binding and activation has long been a component of thyroid cancer molecular imaging and radiotherapy, by promoting expression of the sodium-iodide symporter (NIS) and incorporation of I-131 into thyroid hormones. Here, we report the radiosynthesis and preclinical evaluation of a Zirconium-89 (89Zr) labeled TSHR antibody to serve as a positron emission tomography (PET) diagnostic correlate for therapeutic agents targeting TSHR without reliance on NIS. TSHR human monoclonal antibody K1-70 was conjugated to chelator desferrioxamine-p-benzyl-isothiocyanate, followed by labeling with Zr-89, yielding the radiotracer 89Zr-DFO-TSHR-Ab. The in vitro cellar uptake and binding affinity of 89Zr-DFO-TSHR-Ab were analyzed in three new TSHR stable overexpressing tumor cell lines and their corresponding wild types (WT) with low or no TSHR expression. 89Zr-DFO-TSHR-Ab PET/CT imaging of TSHR expression was evaluated in tumor mouse models bearing one TSHR-positive tumor and other negative control with or without the coinjection of antibody K1-70, and then verified by radiotracer biodistribution study and tumor immunohistochemistry (IHC). The conjugate DFO-TSHR-Ab was labeled with Zr-89 at 37°C for 60min and purified by PD-10 column in radiochemical yields of 68.8 ± 9.9%, radiochemical purities of 98.7 ± 0.8%, and specific activities of 19.1 ± 2.7mCi/mg (n = 5). In vitro cell studies showed 89Zr-DFO-TSHR-Ab had significantly high uptake on TSHR expressing tumor cells with nanomolar affinity and high potency. Preclinical PET/CT imaging revealed that 89Zr-DFO-TSHR-Ab selectively detected TSHR expressing thyroid tumors and displayed improved in vivo performance with the coinjection of unlabeled TSHR antibody K1-70 leading to higher uptake in TSHR expressing tumors than parental WT tumors and physiologic tissues; this observation was confirmed by the biodistribution and immunostaining analyses. We synthesized 89Zr-labeled antibody K1-70 as a new radiopharmaceutical for PET imaging of TSHR. 89Zr-DFO-TSHR-Ab has high radioactive uptake and retention in TSHR expressing tumors and cleared quickly from most background tissues in mouse models. Our study demonstrated that 89Zr-DFO-TSHR-Ab has the potential for PET imaging of TSHR-positive thyroid cancer and monitoring TSHR-targeted therapy.

Lipoma: An Unusual Iodine-131 Uptake on Whole-Body Scanning: A Case Report

Whole-body radioiodine scintigraphy plays a major role in detecting metastases or recurrence of differentiated thyroid cancers. However, radioactive iodine uptake is not specific to thyroid tissue, and many physiological and pathological variants can bind radioactive iodine, resulting in false positives that can compromise the correct interpretation of results. We report the case of a 73-year-old patient with papillary thyroid carcinoma who underwent surgery 2 years ago, and whose whole-body scan, performed in the face of rising thyroglobulin levels, revealed abnormal fixation on the thigh, and further investigations suggested a lipoma. Our aim in reporting this case is to contribute to the knowledge of new false positives linked to iodine-131 fixation, in order to avoid unusual diagnostic errors that can lead to the unnecessary administration of therapeutic doses of iodine-131 or to aberrant surgical interventions.

Visualizing of engineered five-helix bundle protein for blocking SARS-CoV-2 variants in live animals

Variants of Concern (VOCs), and variant under monitoring (VUM) of SARS-CoV-2 have emerged with heightened infectivity, antibody resistance, and vaccine breakthrough. In light of this, it is imperative to establish efficient and streamlined testing models for the prompt detection of newly emerging mutant strains. The 5-Helix Bundle (5-HB) protein was engineered as potent inhibitors predicated on the S2 subunit of the SARS-CoV-2 spike protein, exerting a broad-spectrum inhibitory influence against SARS-CoV-2 infections. Positron emission tomography (PET) quantifications revealed significantly reduced radioactive uptake in infected tissue of 5-HB protein-treated mice. The reduction was much lower than that of untreated infected mice imaged at 4 h (48.6 % reduction), 12 h (45.2 % reduction), and 24 h (36.9 % reduction) (p < 0.01). The newly engineered 5-HB protein features with the capability of binding to conservative pre-fusion spike of SARS-CoV-2 in live animals, highlighting its entry-inhibition capacity for a wide spectrum of SARS-CoV-2 variants.

Discovery of a highly specific radiolabeled antibody targeting B-cell maturation antigen: Applications in PET imaging of multiple myeloma.

Multiple myeloma (MM) is characterized by the uncontrolled proliferation of monoclonal plasma cells (PC) in the bone marrow (BM). B-cell maturation antigen (BCMA) is predominantly expressed in malignant plasma cells, and associated with the proliferation, survival, and progression of various myeloma cells. Given these important roles, BCMA emerges as an ideal target antigen for MM therapy. However, effective stratification of patients who may benefit from targeted BCMA therapy and real-time monitoring the therapeutic efficacy poses significant clinical challenge. This study aims to develop a BCMA targeted diagnostic modality, and preliminarily explore its potential value in the radio-immunotherapy of MM. Using zirconium-89 (89Zr, t1/2 = 78.4 h) for labeling the BCMA-specific antibody, the BCMA-targeting PET tracer [89Zr]Zr-DFO-BCMAh230430 was prepared. The EC50 values of BCMAh230430 and DFO-BCMAh230430 were determined by ELISA assay. BCMA expression was assessed in four different tumor cell lines (MM.1S, RPMI 8226, BxPC-3, and KYSE520) through Western blot and flow cytometry. In vitro binding affinity was determined by cell uptake studies of [89Zr]Zr-DFO-BCMAh230430 in these tumor cell lines. For in vivo evaluation, PET imaging and ex vivo biodistribution studies were conducted in tumor-bearing mice to evaluate imaging performance and systemic distribution of [89Zr]Zr-DFO-BCMAh230430. Immunochemistry analysis was performed to detect BCMA expression in tumor tissues, confirming the specificity of our probe. Furthermore, we explored the anti-tumor efficacy of Lutetium-177 labeled BCMA antibody, [177Lu]Lu-DTPA-BCMAh230430, in tumor bearing-mice to validate its radioimmunotherapy potential. The radiolabeling of [89Zr]Zr-DFO-BCMAh230430 and [177Lu]Lu-DTPA-BCMAh230430 showed satisfactory radiocharacteristics, with a radiochemical purity exceeding 99%. ELISA assay results revealed closely aligned EC50 values for BCMAh230430 and DFO-BCMAh230430, which are 57 pM and 67 pM, respectively. Western blot and flow cytometry analyses confirmed the highest BCMA expression level. Cell uptake data indicated that MM.1S cells hada total cellular uptake (the sum of internalization and surface binding) of 38.3% ± 1.53% for [89Zr]Zr-DFO-BCMAh230430 at 12 h. PET imaging of [89Zr]Zr-DFO-BCMAh230430 displayed radioactive uptake of 7.71 ± 0.67%ID/g in MM.1S tumors and 4.13 ± 1.21%ID/g in KYSE520 tumors at 168 h post-injection (n = 4) (P < 0.05), consistent with ex vivo biodistribution studies. Immunohistochemical analysis of tumor tissues confirmed higher BCMA expression in MM.1S tumors xenograft compared to KYSE520 tumors. Notably, [177Lu]Lu-DTPA-BCMAh230430 showed some anti-tumor efficacy, evidenced by slowed tumor growth. Furthermore, no significant difference in body weight was observed in MM.1S tumor-bearing mice over 14 days of administration with or without [177Lu]Lu-DTPA-BCMAh230430. Our study has successfully validated the essential role of [89Zr]Zr-DFO-BCMAh230430 in non-invasively monitoring BCMA status in MM tumors, showing favorable tumor uptake and specific binding affinity to MM tumors. Furthermore, our research revealed, as a proof-of-concept, the effectiveness of [177Lu]Lu-DTPA-BCMAh230430 in radioimmunotherapy for MM tumors. In conclusion, we present a novel BCMA antibody-based radiotheranostic modality that holds promise for achieving efficient and precise MM diagnostic and therapy.

Affibody-based molecular probe 99mTc-(HE)3ZHER2:V2 for non-invasive HER2 detection in ovarian and breast cancer xenografts.

This study aimed to assess the biodistribution and bioactivity of the affibody molecular probe 99mTc-(HE)3ZHER2:V2, prepared by genetic recombination, and to investigate its potential for targeted human epidermal growth factor receptor 2 (HER2) imaging in SKOV3 ovarian cancer and MDA-MB-361 breast cancer xenografts. Affibody molecules were generated through genetic recombination. The radiochemical purity of the 99mTc-labeled HER2 affibody was determined using reverse phase high performance liquid chromatography (RP-HPLC). Evaluation of HER2 affinity in SKOV3 ovarian cancer cells and MDA-MB-361 breast cancer cells (HER2-positive) was conducted by calculating equilibrium dissociation constants. Biodistribution of the 99mTc-labeled affibody molecular probe was assessed in Balb/c mice bearing SKOV3 tumors. Tumor targeting specificity was evaluated in Balb/c mice using SKOV3, MDA-MB-361, and AT-3 (HER2-negative) xenografts. Affibody (HE)3ZHER2:V2, generated through recombinant gene expression, was successfully labeled with 99mTc, achieving a radiochemical purity of (96.0 ± 1.7)% (n = 3) as determined by RP-HPLC. This molecular probe exhibited specific binding to HER2-positive SKOV3 cells, demonstrating intense radioactive uptake. Biodistribution analysis showed rapid accumulation of 99mTc-(HE)3ZHER2:V2 in HER2-positive tumors post-administration, primarily clearing through the urinary system. Single-photon emission computed tomography imaging conducted 1-3 h after intravenous injection of 99mTc-(HE)3ZHER2:V2 into HER2-positive SKOV3 and MDA-MB-361 nude mouse models confirmed targeted uptake of the molecular probe by the tumors. The molecular probe 99mTc-(HE)3ZHER2:V2 developed in this study effectively targets HER2 for imaging HER2-positive SKOV3 and MDA-MB-361 xenografts in vivo. It exhibits rapid blood clearance without evident toxic effects, suggesting its potential as a valuable marker for detecting HER2 expression in tumor cells.

Association between 99mTc-PSMA SPECT/CT imaging and prostate-specific antigen (PSA) and alkaline phosphatase (ALP) levels post-endocrine therapy in patients with prostate cancer and bone metastases

AimTo investigate the association between positive lesions detected by 99mTc-PSMA SPECT/CT and blood levels of prostate-specific antigen (PSA) and alkaline phosphatase (ALP) in patients with prostate cancer (PCa) and bone metastasis undergoing endocrine therapy. MethodsA retrospective analysis was performed on 43 patients diagnosed with PCa bone metastasis who underwent endocrine therapy. PSA, ALP, whole body bone imaging and 99mTc-PSMA SPECT/CT imaging were collected from all patients (Among them, 17 cases were re-examined 99mTc-PSMA SPECT/CT imaging). According to the results of the first 99mTc-PSMA SPECT/CT imaging for detecting bone metastasis, all cases were divided into two groups: positive group and negative group. The relationship between 99mTc-PSMA imaging and PSA and ALP was analyzed by ROC curve. Fisher exact probability method was used to examine the changes in imaging radioactivity uptake, PSA, and ALP levels in 17 patients after treatment, and P < 0.05 was statistically significant. ResultsAll 43 patients had different degrees of radioactive concentrations on whole-body bone imaging. The first 99mTc-PSMA SPECT/CT imaging showed positive bone metastases in 31 cases and negative bone metastases in 12 cases. ROC curve analysis of PSA and ALP, AUC were 0.778 and 0.770, respectively. When PSA > 1.13 ng/mL, 99mTc-PSMA SPECT/CT imaging diagnostic sensitivity was 93.55%, and specificity was 66.67%. When ALP was >86U/L, the diagnostic sensitivity of 99mTc-PSMA SPECT/CT imaging was 64.52%, and the specificity was 83.33%. In 17 cases, the PSA level decreased in 7 and increased in 10. There were 10 cases of increased ALP and 7 cases of decreased ALP levels. In the second 99mTc-PSMA imaging lesion, there were 9 cases with decreased or no uptake, and 8 cases with increased uptake or number of lesions. The changes in 99mTc-PSMA uptake by Fisher’s exact probability method were statistically significant (P < 0.05, P = 0.006, and P = 0.006, respectively), and ALP level was not statistically significant (P = 0.563). Conclusion99mTc-PSMA SPECT/CT imaging can detect PCa bone metastases, which are related to PSA levels. When PSA > 1.13 ng/mL, the sensitivity of diagnosis and detection of positive bone metastases is higher, and when ALP is >86U/L, 99mTc-PSMA imaging has higher specificity.

Increase 68Ga-FAPI Uptake in Urogenital Tuberculosis.

Urogenital tuberculosis is one of common sites of extrapulmonary tuberculosis. A 60-year-old man with an elevated prostate-specific antigen level underwent multiparametric MRI, which revealed abnormal signals in the prostate. However, the 68Ga-PSMA PET/CT results were unrevealing. Subsequent 68Ga-FAPI PET/CT imaging revealed intense radioactivity uptake in the prostate and mild radioactivity uptake in the left kidney, which was eventually proven due to tuberculosis.