Therapeutic Potential of Sodium Selenite Application for Promoting Radioactive Iodine Avidity in Papillary Thyroid Cancer

Disclosure: D. Toro-Tobon: None. J.C. Morris: None. C. Hilger: None. C.S. Peskey: None. D.M. Jolanta: None. M.M. Ryder: None. Objective: Patients with metastatic differentiated thyroid cancer (DTC) that are radioactive iodine (RAI) refractory (RAIR) have a poor prognosis. Redifferentiation therapy (RDT) has emerged as a potential approach to restore RAI avidity in this disease. The aim of this study was to examine the efficacy and predictors of RAI restoration in RAIR disease, as well as examine the outcomes of patients re-treated with high dose RAI following RDT. Methods: A retrospective review was conducted of 33 patients with RECIST-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic. All patients underwent genomic profiling, and either MEK inhibitor alone or combination BRAF-MEK inhibitors were prescribed for 4 weeks. At week 3, Thyrogen-stimulated I-123 whole body scans were performed. Those with increased RAI avidity in metastatic foci received high dose I-131 therapy using a previously published modified dosimetry protocol. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 12 of 23 (52%) with papillary thyroid cancers (PTC), 4 of 4 (100%) with follicular variant PTCs (FV-PTC), and 7 of 7 (100%) with follicular thyroid cancers (FTC) had restored RAI avidity following RDT using dabrafenib/trametinib (7 for BRAF mutant disease) or trametinib monotherapy (12 for RAS mutant disease). All 11 (100%) RAS mutant tumors (2 PTC, 3 FV-PTC, and 6 FTC) had RAI avidity restoration compared to 7 (36%) with BRAF mutant disease (6 PTC, and 1 FV-PTC). Of the 19 patients (57%) with restored RAI avidity (responders), 18 (94%) received I-131 with a median dose of 294 mCi. The median thyroglobulin (Tg) in responders was 294 mIU/L as compared to 29 mIU/L in non-responders. Following RDT-facilitated I-131 treatment, 94.7% achieved RECIST defined objective response (complete or partial response, stable disease, non-complete response/non-progressive disease) with a median progression free survival of 18 months and an overall survival of 30 months. Overall, patients with FTC (p=0.01), RAS mutation (p<0.001), Tg of 294 mIU/L or more (p=0.03), largest tumor diameter of 1.7 cm or less (p=0.05), bone metastasis (p=0.007), and without locoregional nodal disease (p=0.04), were more likely to demonstrate restored RAI avidity following RDT. Of the entire cohort, 2 (6%) patients experienced histologic transformation to anaplastic thyroid cancer and 5 (15%) patients died, all had had RAI restoration and received high-dose RAI following RDT. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following I-131 therapy in select patients with RAIR-DTC, particularly those with RAS mutations and ‘follicular’ phenotypes. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic transformation. Presentation Date: Saturday, June 17, 2023

TPS10078 Background: Targetable kinase fusions and mutations are common in pediatric and young adult patients with papillary thyroid cancer (TC) and are associated with metastatic disease and lack of response to radioactive iodine therapy (RAI). While survival outcomes are excellent, less than 20% of children with metastatic TC achieve a complete response to standard treatment with surgery and radioactive iodine (RAI). Thus, repeated RAI therapy is common, increasing the risk of pulmonary fibrosis and secondary malignancies. Targeted kinase inhibitors are highly effective at shrinking oncogene-driven TC. Preliminary data suggest that these targeted therapies can improve tumor differentiation and RAI sensitivity. However, optimal integration of targeted therapy with standard of care RAI for TC remains uncertain. The objective of this study is to evaluate if targeted inhibitors in patients with metastatic, oncogene-driven differentiated TC will improve or restore tumor RAI uptake and ultimately induce durable clinical responses in patients with metastatic differentiated TC. Methods: Patients with TC lung metastases, both RAI naïve and refractory, with an identified targetable molecular driver (Table) and intent to start oncogene-specific targeted therapy are eligible for this study. Patients who received a prior oncogene-specific targeted therapy are excluded. A RAI-whole body scan (WBS) is performed at baseline and after 4 weeks of targeted therapy. Patients will be followed for up to 5 years to monitor clinical response. Response parameters include structural (CT, WBS, and/or neck US) and biochemical (thyroglobulin, thyroglobulin antibodies) evaluation. The primary endpoint is the change in RAI avidity between baseline and 4 weeks of treatment. This will be calculated as the ratio of RAI uptake in the lungs/disease sites versus the whole body for each subject at each time point. Secondary endpoints include progression free survival and the proportion of patients who achieve a complete response to the combination of targeted therapy and RAI. Five of 32 patients have been enrolled. Clinical trial information: NCT05024929 . [Table: see text]

The purpose of this study was to detect the relative expression of long non-coding ribonucleic acid (lncRNA) in non-homologous end joining pathway 1 (LINP1) in papillary thyroid cancer (PTC) tissues and cells, and to investigate the molecular mechanisms of abnormal expression and biological function of LINP1. The relative expression of LINP1 in PTC tissues and cells was detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), and the impact of small interfering (si)-LINP1 on the proliferative capacity of PTC cells was studied using Cell Counting Kit-8 (CCK-8) and colony formation assays. After the expression of LINP1 in PTC cells was interfered, flow cytometry was applied to determine the changes in cell cycle distribution and apoptosis rate. The transcription factors binding to the promoter region of LINP1 were predicted by bioinformatics. Next, qRT-PCR assay was adopted to measure the changes in LINP1 expression after interference in the expression of signal transducer and activator of transcription 1 (STAT1). Finally, the changes in the expressions of molecular markers of the adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway were examined via Western blotting assay after the expressions of STAT1 and LINP1 were interfered. It was shown in qRT-PCR results that LINP1 expression was upregulated in 42 out of 53 cases of PTC tissues and in all PTC cells. After interference in the expression of LINP1 in PTC cells, the results of CCK-8 and colony formation assays indicated that the proliferative capacity of the cells was repressed. According to the results of flow cytometry, the cell cycle was arrested at the G1/G0 phase, and the apoptosis rate was increased. In addition, the bioinformatics predicted that STAT1 could bind to the promoter region of LINP1, and the results of qRT-PCR indicated that the expression of LINP1 declined after STAT1 expression was interfered. Moreover, it was indicated in the Western blotting assay after interference in the expressions of STAT1 and LINP1 that the expression of molecular marker (Phosphorylation AMPK, p-AMPK) of the AMPK signaling pathway was altered but the expression of total AMPK did not change. The transcription factor STAT1 promotes the expression of LINP1 in PTC, and highly expressed LINP1 facilitates the proliferation and inhibits the apoptosis of PTC by suppressing the AMPK signaling pathway.

Metastatic differentiated thyroid cancers (DTC) are resistant to traditional chemotherapy. Kinase inhibitors have shown promise in patients with progressive DTC, but dose-limiting toxicity is commonplace. HSP90 regulates protein degradation of several growth-mediating kinases such as RET, and we hypothesized that HSP90 inhibitor (AUY922) could inhibit RET-mediated medullary thyroid cancer (MTC) as well as papillary thyroid cancer (PTC) cell growth and also radioactive iodine uptake by PTC cells. Studies utilized MTC cell lines TT (C634W) and MZ-CRC-1 (M918T) and the PTC cell line TPC-1 (RET/PTC1). Cell viability was assessed with MTS assays and apoptosis by flow cytometry. Signaling target expression was determined by western blot and radioiodine uptake measured with a gamma counter. Prolonged treatment of both MTC cell lines with AUY922 simultaneously inhibited both MAPK and mTOR pathways and significantly induced apoptosis (58.7 and 78.7% reduction in MZ-CRC-1 and TT live cells respectively, following 1 μM AUY922; P<0.02). Similarly in the PTC cell line, growth and signaling targets were inhibited, and also a 2.84-fold increase in radioiodine uptake was observed following AUY922 administration (P=0.015). AUY922 demonstrates in vitro activity against MTC and PTC cell lines. We observed a potent dose-dependent increase in apoptosis in MTC cell lines following drug administration confirming its anti-tumorigenic effects. Western blots confirm inhibition of pro-survival proteins including AKT suggesting this as the mechanism of cell death. In a functional study, we observed an increase in radioiodine uptake in the PTC cell line following AUY922 treatment. We believe HSP90 inhibition could be a viable alternative for treatment of RET-driven chemo-resistant thyroid cancers.

Effects of I-131 therapy on gonads and pregnancy outcome in patients with thyroid cancer

Epidemiology of Thyroid Cancer.

Long non-coding RNA (lncRNA) PITPNA antisense RNA 1 (PITPNA-AS1) expression characteristics, function, and mechanism in papillary thyroid cancer are unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied for detecting PITPNA-AS1, UNC-5 netrin receptor B (UNC5B) mRNA, and miR-129-5p expressions in papillary thyroid cancer tissues and cell lines. EdU assay, cell counting kit-8 (CCK-8) assay, wound healing assay, and flow cytometry analysis were performed to investigate the biological functions of PITPNA-AS1 in papillary thyroid cancer. Dual-luciferase reporter assay was utilized for determining whether PITPNA-AS1 and miR-129-5p, as well as UNC5B and miR-129-5p could directly bind to each other. Western blot assay was employed for measuring UNC5B protein expression level in papillary thyroid cancer cell lines. PITPNA-AS1 and UNC5B expressions were markedly increased in papillary thyroid cancer tissues and cell lines while miR-129-5p expression was down-regulated. Knockdown of PITPNA-AS1 could significantly inhibit papillary thyroid cancer cell growth and migration and promote cell apoptosis while UNC5B overexpression plasmids or miR-129-5p inhibitors counteracted the knockdown effect of PITPNA-AS1 on papillary thyroid cancer cells. PITPNA-AS1 targeted miR-129-5p to repress its expression and miR-129-5p targeted UNC5B to repress its expression. Silencing PITPNA-AS1 reduced the expression of UNC5B via regulating miR-129-5p expression. PITPNA-AS1 facilitated papillary thyroid cancer cell proliferation and migration, and suppressed apoptosis through miR-129-5p/UNC5B axis.

The incidence of thyroid cancer has grown over the last three decades, and in the United States, it has increased more than any other cancer (1, 2). Differentiated thyroid cancer (DTC) is the most common of all thyroid cancers, accounting for approximately 90% of cases, and includes papillary, follicular, and hurthle cell histologies (3). Although most patients with DTC have a favorable prognosis with standard treatments, including surgery, radioactive iodine (RAI), and TSH suppression, 10–15% of patients will develop disease refractory to RAI therapy (4, 5). These patients have a median overall survival of 2.5 to 3.5 years (6, 7). For decades, standard therapy for RAI-refractory DTC consisted of cytotoxic chemotherapy with doxorubicin, with unsatisfactory results and side effects (8). The discovery of oncogenic v-raf murine sarcoma viral oncogene homolog B (BRAF) mutations in papillary thyroid cancer in 2003 and the recognition that thyroid cancers are also highly vascular paved the way for the use of sorafenib in metastatic RAI-refractory DTC. A serine-threonine kinase inhibitor, sorafenib, has been found to have multiple targets including VEGFR1–3, platelet derived growth factor receptor beta (PDGFR ), V-Raf-1 murine Leukemia viral oncogene homolog (RAF-1), and BRAF (9). Its activity in DTC, first shown in phase II studies, resulted in the design and execution of DECISION: a double-blind, randomized, placebo-controlled phase III trial evaluating the efficacy and safety of sorafenib in patients with locally advanced or metastatic RAI-refractory DTC (10–12). DECISION was important in helping to define patients with RAI-refractory DTC that were in need of systemic therapy in addition to determining the benefit of sorafenib. Patients were eligible if they met criteria for RAI-refractory disease, defined either as: 1) Having received a total lifetime dose of greater than or equal to 600mCi, 2) The presence of progressing lesions that were RAI non-Avid, or 3) The presence of lesions that had progressed in the period immediately after a therapeutic dose of RAI (12). Furthermore, patients needed to have met RECIST (Response Evaluation Criteria In Solid Tumors) criteria for progressive disease in the year before going on study, which included progression of target lesions by 20% or the development of new lesions (12). The study met its primary endpoint; the median progression free survival (PFS) in the sorafenib arm was 10.8 months, compared to 5.8 months in the placebo arm (hazard ratio, 0.587; P .0001) (12). In November of 2013, based on the data from DECISION, sorafenib became the first multikinase inhibitor (MKI) to be approved by the Food and Drug Administration for the treatment of RAI-refractory progressive DTC. This was practice changing; patients now had a tolerable systemic therapy to manage progressive, RAI-refractory disease. However, the median PFS for patients who receive sorafenib in the first-line setting is 10.8 months (12), leaving open the question of which therapies to consider in the second-line setting. This is especially important because most patients who stop treatment because of disease progression or the development of intolerable or unmanageable adverse events often maintain a good performance status and are candidates for subsequent therapy. In this issue of the JCEM, Dadu et al (13) report results of their retrospective analysis examining the efficacy of second-line therapy in patients with metastatic, RAI-refractory DTC previously treated with sorafenib.

RETRACTED: KDM5B-mediated microRNA-448 up-regulation restrains papillary thyroid cancer cell progression and slows down tumor growth via TGIF1 repression

Differentiated thyroid cancer and selenium supplements for protection of salivary glands from 131I treatment.

Papillary thyroid carcinoma is the most frequent histological subtype of thyroid cancer with a high incidence. We aimed to explore the function of circular RNA_0039411 (circ_0039411) and its associated mechanism in papillary thyroid carcinoma progression. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were conducted to determine the expression of RNA and protein, respectively. The colony formation ability, migration, invasion, and apoptosis were analyzed by colony formation assay, transwell migration assay, transwell invasion assay, and flow cytometry. Cell glycolytic metabolism was analyzed using fluorescence-based glucose assay kit and fluorescence-based lactate assay kit. Dual-luciferase reporter assay and RNA-Pull-Down Assay were performed to validate the binding between microRNA-423-5p (miR-423-5p) and circ_0039411 or SRY-box transcription factor 4 (SOX4). The xenograft tumor model was used to assess the role of circ_0039411 in the tumor growth in vivo. Circ_0039411 was highly expressed in papillary thyroid carcinoma tissues and cell lines compared with adjacent normal tissues and NTHY-ORI3.1 cells. Circ_0039411 interference suppressed the colony formation ability, migration, invasion, and glycolysis but promoted the apoptosis of papillary thyroid carcinoma cells. MiR-423-5p was a target of circ_0039411 in papillary thyroid carcinoma cells. Circ_0039411 knockdown-mediated effects in papillary thyroid carcinoma cells were largely overturned by the silence of miR-423-5p. MiR-423-5p bound to the 3' untranslated region (3'UTR) of SOX4. SOX4 overexpression largely reversed circ_0039411 silencing-mediated effects in papillary thyroid carcinoma cells. Circ_0039411 positively regulated SOX4 expression by sponging miR-423-5p in papillary thyroid carcinoma cells. Circ_0039411 silencing notably suppressed the growth of xenograft tumors in vivo. Circ_0039411 promoted the malignant behaviors of papillary thyroid carcinoma cells partly depending on the regulation of the miR-423-5p/SOX4 axis.

Iodine or Not (IoN) for Low-risk Differentiated Thyroid Cancer: The Next UK National Cancer Research Network Randomised Trial following HiLo

Knockdown of TRIM44 inhibits the proliferation and invasion in papillary thyroid cancer cells through suppressing the Wnt/β-catenin signaling pathway

MicroRNAs (miRNAs/miRs) are widely dysregulated in papillary thyroid cancer (PTC). Dysregulated miRNAs, together with their target genes, comprise a complex network that has been implicated in the regulation of PTC pathogenesis. Further knowledge of the functional roles of aberrantly expressed miRNAs in PTC, and the underlying molecular mechanisms, may assist in the identification of novel therapeutic targets. miR‑766 has been well studied in human cancer; however, the expression status, specific roles and regulatory mechanisms of miR‑766 in PTC remain unclear. The present study aimed to detect miR‑766 expression in PTC tissues and cell lines, to explore the biological roles of miR‑766 in the malignant biological behaviors of PTC cells, and to determine the underlying mechanism of action of miR‑766 in PTC cells. The results revealed that miR‑766 was downregulated in PTC tissues and cell lines, and its downregulation was strongly associated with TNM stage and lymph node metastasis. Overexpression of miR‑766 inhibited PTC cell proliferation, colony formation, migration and invasion, promoted cell apoptosis and reduced tumor growth invivo. Mechanistically, insulin receptor substrate2 (IRS2) was identified as a direct target of miR‑766 in PTC cells. IRS2 was upregulated in PTC tissues, and this was inversely correlated with miR‑766 expression. Inhibition of IRS2 simulated the tumor suppressor activity of miR‑766 in PTC cells. Restoration of IRS2 expression negated the tumor‑suppressing effects of miR‑766 overexpression on PTC cells. Notably, miR‑766 directly targeted IRS2 to inhibit activation of the phosphoinositide3‑kinase (PI3K)/protein kinaseB (Akt) pathway in PTC cells invitro and invivo. Overall, these findings indicated that miR‑766 may inhibit the malignant biological behaviors of PTC cells by directly targeting IRS2 and regulating the PI3K/Akt pathway, thus suggesting that this miRNA may be a promising therapeutic target for PTC.

Radioactive iodine (RAI) is the mainstay of treatment for differentiated thyroid carcinoma (DTC). Nevertheless, the mechanism of RAI resistance that occurs in many patients with DTC remains unknown. We aimed to elucidate the role of post-translational regulation of radioiodine uptake. We analyzed the expression pattern of the ribosomal glycosylphosphatidylinositol transamidase (GPIT) complex in freshly excised tumors from 10 patients with DTC. We used functional RAI uptake assays to assess the role of GPIT in iodine uptake both in vivo and in vitro. The effects of MEK inhibition on the GPIT subunit PIGU and the sodium iodide symporter (NIS) were assessed in three DTC cell lines and in four human DTC biopsies. We used a multivariable logistic regression model to study the role of PIGU in the response to RAI treatment in advanced DTC. All statistical tests were two-sided. Expression profiling of different GPIT complex subunits revealed statistically significantly lower expression of PIGU in papillary carcinomas than in matched normal thyroid tissue (P < .001). Expression of PIGU in the K1 human papillary carcinoma cell line resulted in a robust increase in NIS glycosylation and trafficking to the cell membrane, accompanied by a robust increase in I125 uptake both in vitro (465 200 ± 56 343 vs 1236 ± 156 counts per million, P < .001) and in vivo (128 945 ± 28 556 vs 7963 ± 192 counts per million, P < .001, n = 5 mice per group). Treatment with the MEK inhibitors U0126 and PD302 rescued PIGU expression. Finally, the PIGU expression levels in tumors of 18 patients with recurrent DTC were associated with a biochemical response to RAI treatment (hazard ratio = 8.06, 95% confidence interval = 3.72 to 12.3, P = .001). We showed that downregulation of PIGU in DTC determines NIS function and RAI avidity. This represents a novel mechanism for RAI resistance.