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Background: The 2022 World Health Organization classification introduced the term high-grade follicular cell-derived nonanaplastic thyroid carcinoma (HGFCTC) to define invasive/infiltrative nonanaplastic thyroid carcinoma with high-grade features, including poorly differentiated thyroid carcinoma and high-grade differentiated thyroid carcinoma. Our objectives were to compare clinicopathological characteristics, oncologic outcomes, and mutation profiles among HGFCTC subgroups to better inform prognostication and treatment. Methods: In this single-center, retrospective cohort study of 252 patients who had surgery for HGFCTC from 1986 to 2020, we categorized HGFCTC and its related entity, "encapsulated noninvasive neoplasms of follicular cells with high-grade features," into five subgroups: (A) encapsulated noninvasive, (B) encapsulated with capsular invasion only (minimally invasive), (C) encapsulated angioinvasive with focal vascular invasion (VI), (D) encapsulated angioinvasive with extensive VI, and (E) infiltrative tumors. Next-generation sequencing with Memorial Sloan Kettering Cancer Center-Integrated Mutation Profiling of Actionable Cancer Targets was available for 117/252 patients to investigate differences in mutation profiles. Results: The cohort comprised 50% infiltrative, 33% encapsulated angioinvasive, and 18% encapsulated noninvasive/minimally invasive tumors. No patients with encapsulated noninvasive or minimally invasive disease had regional or distant metastases at presentation. Patients with infiltrative tumors were significantly more likely to present with T3/T4 disease (71%), regional metastases (55%), and distant metastases (25%) ( p ≤ 0.003 ). Five-year disease-specific survival was poorer in patients with infiltrative disease (67.7%), compared to encapsulated angioinvasive focal VI (90.4%), encapsulated angioinvasive extensive VI (88.1%), and encapsulated noninvasive/minimally invasive (100%) ( p = 0.0002) subgroups. Common mutations were TERT (42%), BRAF V600E (29%), NRAS (27%), EIF1AX (11%), and TP53 (9%). Pathways altered included RTK/RAS/RAF/MAPK (69%), PI3K/AKT/MTOR (14%), histone methyltransferases (9%), and SWI/SNF chromatin remodeling complex (8%). Subgroup analysis showed the infiltrative subgroup was mainly BRAF V600E -driven, and the encapsulated angioinvasive and minimally invasive subgroups were NRAS- driven. Encapsulated noninvasive tumors had a different mutation profile, with DICER1 as the main driver mutation. Conclusions: HGFCTC comprises different subgroups with different clinical behaviors determined by the extent of vascular invasion and degree of infiltration. Excellent recurrence and survival outcomes occur in encapsulated noninvasive and minimally invasive tumors compared to infiltrative tumors. Infiltrative tumors are largely " BRAF -like," whereas encapsulated angioinvasive tumors are " RAS -like." Encapsulated noninvasive tumors have a particularly unique molecular profile consisting of DICER1 mutations and a lack of BRAF V600E mutations.

Thyroid nodules are a common endocrine condition with an increasing incidence over the decades. Data-independent acquisition has been widely utilized in discovery proteomics to identify disease biomarkers and therapeutic targets. To analyze the thyroid disease-related proteome in a high-throughput, reproducible and reliable manner, we introduce thyroid-specific peptide spectral libraries. Here, we generated four deep-coverage libraries through four mass spectrometers comprising Q Exactive HF, Orbitrap Exploris 480, ZenoTOF 7600, and timsTOF Pro. These libraries encompass over 215,000 precursors, 172,000 peptides, and 12,000 proteins, derived from 245 tissue samples across nine histological types and 50 cell lines across six histological types. Moreover, the spectral libraries are applied to nine types of thyroid samples to facilitate the exploration of disease-specific proteins. Our spectral libraries serve as a valuable resource for analyzing thyroid protein content, facilitating deeper insights into thyroid disorders., Competing Interests: Competing interests: T.G. and Y.Z. are shareholders of Westlake Omics Inc. The other authors declare no competing interests in this paper., (© 2024. The Author(s).)

Anaplastic thyroid cancer (ATC) is a clinically aggressive malignancy with a dismal prognosis. Combined BRAF/MEK inhibition offers significant therapeutic benefit in patients with BRAF V600E -mutant ATCs. However, relapses are common and overall survival remains poor. Compared with differentiated thyroid cancer, a hallmark of ATCs is significant infiltration with myeloid cells, particularly macrophages. ATCs are most common in the aging population, which also has an increased incidence of TET2 -mutant clonal hematopoiesis (CH). CH-mutant macrophages have been shown to accelerate CH-associated pathophysiology including atherosclerosis. However, the clinical and mechanistic contribution of CH-mutant clones to solid tumour biology, prognosis and therapeutic response has not been elucidated. Here we show that TET2 -mutant CH is enriched in the tumour microenvironment of patients with solid tumours and associated with adverse prognosis in ATC patients. We find that Tet2 -mutant macrophages selectively infiltrate mouse Braf V600E -mutant ATC and that their overexpression of Tgfβ-family ligands mediates resistance to BRAF/MEK inhibition. Importantly, inhibition of Tgfβ signaling restores sensitivity to MAPK pathway inhibition, opening a path for synergistic strategies to improve outcomes of patients with ATCs and concurrent CH.

Background: Fluorine 18-labelled tetrafluoroborate ([ 18 F]TFB) is a substrate for the sodium/iodide symporter. In thyroid cancer, [ 18 F]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 [ 18 F]TFB and compare its properties to [ 124 I]IodinePET/CT in patients with metastatic thyroid cancer., Methods: Five patients were included in a prospective study. All patients received PET/CT 1 h after injection of 356 ± 12 MBq [ 18 F]TFB and were given 230 ± 9 MBq [ 124 I]Iodine orally on the same day, followed by PET/CT after 48 h. Before redifferentiation therapy, patients underwent an additional baseline [ 124 I]Iodine PET/CT. Cases were analyzed by two board-certified specialists. Detection rates and Spearman correlation for [ 18 F]TFB and [ 124 I]Iodine were calculated., Results: Three 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 [ 18 F]TFB and 30 (91%) on [ 124 I]Iodine imaging. In the patients who underwent redifferentiation therapy, 48 lesions were newly seen on [ 124 I]Iodine PET/CT with a median SUV max of 3.3 (range, 0.4-285.0). All of these lesions were [ 18 F]TFB-negative., Conclusion: [ 18 F]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 Number: NCT03196518, registered on June 22, 2017., (© 2024. The Author(s).)

Background: Diffuse sclerosing papillary thyroid carcinoma (DSPTC) is an aggressive histopathologic subtype of papillary thyroid carcinoma. Correlation between genotype and phenotype has not been comprehensively described. This study aimed to describe the genomic landscape of DSPTC comprehensively using next-generation sequencing (NGS), analyze the prognostic implications of different mutations, and identify potential molecular treatment targets., Methods: Tumor tissue was available for 41 DSPTC patients treated at Memorial Sloan Kettering Cancer Center between 2004 and 2021. After DNA extraction, NGS was performed using the Memorial Sloan Kettering Integrated Mutation Profiling of Actionable Cancer Targets platform, which sequences 505 critical cancer genes. Clinicopathologic characteristics were compared using the chi-square test. The Kaplan-Meier method and log-rank statistics were used to compare outcomes., Results: The most common mutation was RET fusion, occurring in 32% (13/41) of the patients. Other oncologic drivers occurred in 68% (28/41) of the patients, including 8 BRAF V600E mutations (20%) and 4 USP8 mutations (10%), which have not been described in thyroid malignancy previously. Patients experienced RET fusion-positive tumors at a younger age than other drivers, with more aggressive histopathologic features and more advanced T stage (p = 0.019). Patients who were RET fusion-positive had a significantly poorer 5-year recurrence-free survival probability than those with other drivers (46% vs 84%; p = 0.003; median follow-up period, 45 months). In multivariable analysis, RET fusion was the only independent risk factor for recurrence (hazard ratio [HR], 7.69; p = 0.017)., Conclusion: Gene-sequencing should be strongly considered for recurrent DSPTC due to significant prognostic and treatment implications of RET fusion identification. The novel finding of USP8 mutation in DSPTC requires further investigation into its potential as a driver mutation., (© 2024. Society of Surgical Oncology.)

In the clinical development of farnesyltransferase inhibitors (FTIs) for HRAS-mutant tumors, responses varied by cancer type. Co-occurring mutations may affect responses. We aimed to uncover cooperative genetic events specific to HRAS-mutant tumors and to study their effect on sensitivity to FTIs. Using targeted sequencing data from the MSK-IMPACT and Dana-Farber Cancer Institute Genomic Evidence Neoplasia Information Exchange databases, we identified comutations that were observed predominantly in HRAS-mutant versus KRAS-mutant or NRAS-mutant cancers. HRAS-mutant cancers had a higher frequency of coaltered mutations (48.8%) in the MAPK, PI3K, or RTK pathway genes, compared with KRAS-mutant (41.4%) and NRAS-mutant (38.4%) cancers (p < 0.05). Class 3 BRAF, NF1, PTEN, and PIK3CA mutations were more prevalent in HRAS-mutant lineages. To study the effects of comutations on sensitivity to FTIs, Hras G13R was transfected into "RASless" (Kras lox/lox /Hras -/- /Nras -/- /RERT ert/ert ) mouse embryonic fibroblasts (MEFs), which sensitized nontransfected MEFs to tipifarnib. Comutation in the form of Pten or Nf1 deletion and Pik3ca H1047R transduction led to resistance to tipifarnib in Hras G13R -transfected MEFs in the presence or absence of Kras WT , whereas Braf G466E transduction led to resistance to tipifarnib only in the presence of Kras WT . Combined treatment with tipifarnib and MEK inhibition sensitized cells to tipifarnib in all settings, including in MEFs with PI3K pathway comutations. HRAS-mutant tumors demonstrate lineage-dependent MAPK or PI3K pathway alterations, which confer resistance to tipifarnib. The combined use of FTIs and MEK inhibition is a promising strategy for HRAS-mutant tumors., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

RBM10 modulates transcriptome-wide cassette exon splicing. Loss-of-function RBM10 mutations are enriched in thyroid cancers with distant metastases. Analysis of transcriptomes and genes mis-spliced by RBM10 loss showed pro-migratory and RHO/RAC signaling signatures. RBM10 loss increases cell velocity. Cytoskeletal and ECM transcripts subject to exon-inclusion events included vinculin (VCL), tenascin C (TNC) and CD44. Knockdown of the VCL exon inclusion transcript in RBM10 -null cells reduced cell velocity, whereas knockdown of TNC and CD44 exon-inclusion isoforms reduced invasiveness. RAC1-GTP levels were increased in RBM10 -null cells. Mouse Hras G12V /Rbm1O KO thyrocytes develop metastases that are reversed by RBM10 or by combined knockdown of VCL, CD44 and TNC inclusion isoforms. Thus, RBM10 loss generates exon inclusions in transcripts regulating ECM-cytoskeletal interactions, leading to RAC1 activation and metastatic competency. Moreover, a CRISPR-Cas9 screen for synthetic lethality with RBM10 loss identified NFkB effectors as central to viability, providing a therapeutic target for these lethal thyroid cancers., Competing Interests: J.A.F. is a co-inventor of intellectual property focused on HRAS as a biomarker for treating cancer using tipifarnib which has been licensed by MSK to Kura Oncology. J.A.F. received prior research funding from Eisai and was a former consultant for LOXO Oncology, both unrelated to the current manuscript. B.R.U. and J.A.K are co-inventors of intellectual property (HRAS as a biomarker of tipifarnib efficacy) that has been licensed by MSK to Kura Oncology. O.A.-W. has served as a consultant for H3B Biomedicine, Foundation Medicine Inc., Merck, Prelude Therapeutics, and Janssen, and is on the Scientific Advisory Board of Envisagenics Inc., AIChemy, Harmonic Discovery Inc., and Pfizer Boulder. O.A.-W. has received prior research funding from H3B Biomedicine, Nurix Therapeutics, Minovia Therapeutics, and LOXO Oncology unrelated to the current manuscript. R.K.B. is an inventor on patent applications filed by Fred Hutchinson Cancer Center related to modulating splicing for cancer therapy. R.K.B. and O.A.-W. are founders and scientific advisors of Codify Therapeutics, hold equity in this company and receive research support from this company unrelated to the current manuscript. R.K.B. is a founder and scientific advisor of Synthesize Bio and holds equity in this company. A.R.G is currently an Associate Professor of Surgery at the University of Sydney, Australia. M.S. is currently employed by Loxo Oncology.The remaining authors declare no competing interests.

Aims: Papillary thyroid carcinoma, tall cell subtype (PTC-TC) is a potentially aggressive histotype. The latest World Health Organisation (WHO) classification introduced a novel class of tumours; namely, high-grade differentiated thyroid carcinoma (HGDTC), characterised by elevated mitotic count and/or necrosis, which can exhibit a tall cell phenotype (HGDTC-TC)., Methods and Results: We analysed the clinical outcomes in a large retrospective cohort of 1456 consecutive thyroid carcinomas with a tall cell phenotype, including PTC-TC and HGDTC-TC. HGDTC-TC is uncommon, accounting for 5.3% (77 of 1379) of carcinomas with tall cell morphology. HGDTC-TC was associated with significantly older age, larger tumour size, angioinvasion, gross extrathyroidal extension, higher AJCC pT stage, positive resection margin and nodal metastasis (P < 0.05). Compared with PTC-TC, HGDTC was associated with a significantly decreased DSS, LRDFS and distant metastasis-free survival (DMFS; P < 0.001). The 10-year DSS was 72 and 99%, the 10-year LRDFS was 61 and 92% and the 10-year DMFS was 53 and 97%, respectively, for HGDTC-TC and PTC-TC. On multivariate analysis, the classification (HGDTC-TC versus PTC-TC) was an independent adverse prognostic factor for DSS, LRDF, and DMFS when adjusted for sex, age, angioinvasion, margin status, AJCC pT and pN stage., Conclusions: Compared with PTC-TC, HGDTC-TC is associated with adverse clinicopathological features, a higher frequency of TERT promoter mutations (59% in HGDTC-TC versus 34% in PTC-TC) and incurs a significantly worse prognosis. HGDTC-TC is an independent prognostic factor for carcinoma with tall cell morphology. This validates the concept of HGDTC and the importance of tumour necrosis and high mitotic count for accurate diagnosis and prognosis of differentiated thyroid carcinomas., (© 2024 John Wiley & Sons Ltd.)

Background: Genomic profiling is now available for risk stratification of cytologically indeterminate thyroid nodules (ITNs). Mutations in RAS genes ( HRAS , NRAS , KRAS ) are found in both benign and malignant thyroid nodules, although isolated RAS mutations are rarely associated with aggressive tumors. Because the long-term behavior of RAS -mutant ITNs is not well understood, most undergo immediate surgery. In this multicenter retrospective cohort study, we characterize tumor growth kinetics of RAS -mutant ITNs followed with active surveillance (AS) using serial ultrasound (US) scans and examine the histopathologic diagnoses of those surgically resected. Methods: US and histopathologic data were analyzed retrospectively from two cohorts: (1) RAS -mutant ITNs managed with AS at three institutions (2010-2023) and (2) RAS -mutant ITNs managed with immediate surgery at two institutions (2016-2020). AS cohort subjects had ≥3 months of follow-up and two or more US scans. Cumulative incidence of nodule growth was determined by the Kaplan-Meier method and growth by ≥72% change in tumor volume. Pathological diagnoses for the immediate surgery cohort were analyzed separately. Results: Sixty-two patients with 63 RAS -mutated ITNs under AS had a median diameter of 1.7 cm (interquartile range [IQR] 1.2-2.6) at time of diagnosis. During a median AS period of 23 months (IQR 9.5-53.5 months), growth was observed in 12 of 63 nodules (19.0%), with a cumulative incidence of 1.9% (1 year), 23.0% (3 years), and 28.0% (5 years). Most nodules (81.0%) demonstrated stability. Surgery was ultimately performed in 6 nodules, of which 1 (16.7%) was malignant. In the cohort of 209 RAS -mutant ITNs triaged to immediate surgery, 33% were malignant (23.9% American Thyroid Association [ATA] low-risk cancers, 7.2% ATA intermediate-risk, and 1.9% ATA high-risk. During a median follow-up of 6.9 (IQR 4.4-7.1) years, there were no disease-specific deaths in these patients. Conclusions: We describe the behavior of RAS -mutant ITNs under AS and find that most demonstrate stability over time. Of the resected RAS -mutant nodules, most were benign; of the cancers, most were ATA low-risk. Immediate surgical resection of all RAS -mutant ITNs appears to be a low-value practice. Further research is needed to help define cases most appropriate for AS or immediate surgery.

Purpose: The prognostic importance of RET and RAS mutations and their relationship to clinicopathologic parameters and outcomes in medullary thyroid carcinoma (MTC) need to be clarified. Experimental Design: A multicenter retrospective cohort study was performed utilizing data from 290 patients with MTC. The molecular profile was determined and associations were examined with clinicopathologic data and outcomes. Results: RET germ line mutations were detected in 40 patients (16.3%). Somatic RET and RAS mutations occurred in 135 (46.9%) and 57 (19.8%) patients, respectively. RET M918T was the most common somatic RET mutation ( n  = 75). RET somatic mutations were associated with male sex, larger tumor size, advanced American Joint Committee Cancer (AJCC) stage, vascular invasion, and high International Medullary Thyroid Carcinoma Grading System (IMTCGS) grade. When compared with other RET somatic mutations, RET M918T was associated with younger age, AJCC (eighth edition) IV, vascular invasion, extrathyroidal extension, and positive margins. RET somatic or germ line mutations were significantly associated with reduced distant metastasis-free survival on univariate analysis, but there were no significant independent associations on multivariable analysis, after adjusting for tumor grade and stage. There were no significant differences in outcomes between RET somatic and RET germ line mutations, or between RET M918T and other RET mutations. Other recurrent molecular alterations included TP53 (4.2%), ARID2 (2.9%), SETD2 (2.9%), KMT2A (2.9%), and KMT2C (2.9%). Among them, TP53 mutations were associated with decreased overall survival (OS) and disease-specific survival (DSS), independently of tumor grade and AJCC stage. Conclusions: RET somatic mutations were associated with high-grade, aggressive primary tumor characteristics, and decreased distant metastatic-free survival but this relationship was not significant after accounting for tumor grade and disease stage. RET M918T was associated with aggressive primary tumors but was not independently associated with clinical outcomes. TP53 mutation may represent an adverse molecular event associated with decreased OS and DSS in MTC, but its prognostic value needs to be confirmed in future studies.

Mutations in the promoter of the telomerase reverse transcriptase (TERT) gene are the paradigm of a cross-cancer alteration in a noncoding region. TERT promoter mutations (TPM) are biomarkers of poor prognosis in cancer, including thyroid tumors. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert-123C>T) and crossed it with thyroid-specific BrafV600E-mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all BrafV600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of BrafV600E+Tert-123C>T and BrafV600E+K5-Tert mice progressed to poorly differentiated cancers at week 20, respectively. Tert-upregulated tumors showed increased mitosis and necrosis in areas of solid growth, and older animals displayed anaplastic-like features, that is, spindle cells and macrophage infiltration. Murine TPM increased Tert transcription in vitro and in vivo, but temporal and intratumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine, and chemokine signaling, were overactivated. These models constitute useful preclinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs., Implications: Telomerase-driven cancer progression activates pathways that can be dissected and perhaps therapeutically exploited., (©2023 American Association for Cancer Research.)

Background: Very little was known about the molecular pathogenesis of thyroid cancer until the late 1980s. As part of the Centennial celebration of the American Thyroid Association, we review the historical discoveries that contributed to our current understanding of the genetic underpinnings of thyroid cancer. Summary: The pace of discovery was heavily dependent on scientific breakthroughs in nucleic acid sequencing technology, cancer biology, thyroid development, thyroid cell signaling, and growth regulation. Accordingly, we attempt to link the primary observations on thyroid cancer molecular genetics with the methodological and scientific advances that made them possible. Conclusions: The major genetic drivers of the common forms of thyroid cancer are now quite well established and contribute to a significant extent to how we diagnose and treat the disease. However, many challenges remain. Future work will need to unravel the complexity of thyroid cancer ecosystems, which is likely to be a major determinant of their biological behavior and on how they respond to therapy.

The genomic simplicity of differentiated cancers derived from thyroid follicular cells offers unique insights into how oncogenic drivers impact tumour phenotype. Essentially, the main oncoproteins in thyroid cancer activate nodes in the receptor tyrosine kinase-RAS-BRAF pathway, which constitutively induces MAPK signalling to varying degrees consistent with their specific biochemical mechanisms of action. The magnitude of the flux through the MAPK signalling pathway determines key elements of thyroid cancer biology, including differentiation state, invasive properties and the cellular composition of the tumour microenvironment. Progression of disease results from genomic lesions that drive immortalization, disrupt chromatin accessibility and cause cell cycle checkpoint dysfunction, in conjunction with a tumour microenvironment characterized by progressive immunosuppression. This Review charts the genomic trajectories of these common endocrine tumours, while connecting them to the biological states that they confer., (© 2023. Springer Nature Limited.)

Objective: Exposure to therapeutic radioactive iodine (RAI) is associated with an increased relative risk of myeloid malignancies. Clonal hematopoiesis (CH) is a precursor state that can be detected in blood of healthy individuals decades before overt development of leukemia. We prospective studied the effects of RAI on CH., Design: Prospective cohort study., Patients and Measurements: We examined the effect of RAI on CH in 20 patients exposed to RAI for thyroid carcinoma and 20 age-matched unexposed controls. CH status was determined at baseline, 6, 12, 18 and 24 months. We also examined the effect of CH on structural progression of disease., Results: No CH mutations were observed in the patient population that were not present at baseline. Using a variant allelic fraction (VAF) of 2% to define CH, 6/20 older patients (55-80 years old) had CH compared to 2/20 younger patients (20-40 years old) (p = 0.11). Six patients exposed to RAI had CH compared to two patients not exposed to RAI (30% vs. 10%, p = 0.11). There was no significant difference in CH VAF increase in patients treated with RAI compared to untreated age-matched controls (3.8% vs. 1.2%, p = 0.2). CH was significantly associated with somatic BRAFV600E mutations and with worse progression-free survival in the overall cohort as well as among BRAFV600E-mutant tumors., Conclusions: There was no increase in CH in patients treated with RAI over a 2-year follow-up period. Larger studies with longer follow-up periods are needed to investigate the association between RAI and clonal dynamics. The presence of CH is associated with worse structural progression in both BRAFV600E-mutant and wild-type thyroid cancers., (© 2023 John Wiley & Sons Ltd.)

Purpose: The determinants of response or resistance to radioiodine (RAI) are unknown. We aimed to identify genomic and transcriptomic factors associated with structural responses to RAI treatment of metastatic thyroid cancer, which occur infrequently, and to test whether high MAPK pathway output was associated with RAI refractoriness., Experimental Design: Exceptional response to RAI was defined as reduction of tumor volume based on RECIST v1.1. We performed a retrospective case-control study of genomic and transcriptomic characteristics of exceptional responders (ER; n = 8) versus nonresponders (NR; n = 16) matched by histologic type and stage at presentation on a 1:2 ratio., Results: ER are enriched for mutations that activate MAPK through RAF dimerization (RAS, class 2 BRAF, RTK fusions), whereas NR are associated with BRAFV600E, which signals as a monomer and is unresponsive to negative feedback. ER have a lower MAPK transcriptional output and a higher thyroid differentiation score (TDS) than NR (P < 0.05). NR are enriched for 1q-gain (P < 0.05) and mutations of genes regulating mRNA splicing and the PI3K pathway. BRAFV600E tumors with 1q-gain have a lower TDS than BRAFV600E/1q-quiet tumors and transcriptomic signatures associated with metastatic propensity., Conclusions: ER tumors have a lower MAPK output and higher TDS than NR, whereas NR have a high frequency of BRAFV600E and 1q-gain. Molecular profiling of thyroid cancers and further functional validation of the key findings discriminating ER from NR may help predict response to RAI therapy., (©2023 American Association for Cancer Research.)

Mutations in the promoter of the telomerase reverse transcriptase ( TERT ) gene are the paradigm of a cross-cancer alteration in a non-coding region. TERT promoter mutations (TPMs) are biomarkers of poor prognosis in several tumors, including thyroid cancers. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert -123C>T ) and crossed it with thyroid-specific Braf V600E -mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all Braf V600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of Braf V600E +Tert -123C>T and Braf V600E +K5-Tert mice progressed to poorly differentiated thyroid cancers at week 20, respectively. Braf+Tert tumors showed increased mitosis and necrosis in areas of solid growth, and older animals from these cohorts displayed anaplastic-like features, i.e., spindle cells and macrophage infiltration. Murine Tert promoter mutation increased Tert transcription in vitro and in vivo , but temporal and intra-tumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine and chemokine signaling, were overactivated. Braf+Tert animals remained responsive to MAPK pathway inhibitors. These models constitute useful pre-clinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs.

Therapy resistance is a major challenge in the treatment of cancer. Here, we performed CRISPR-Cas9 screens across a broad range of therapies used in acute myeloid leukemia to identify genomic determinants of drug response. Our screens uncover a selective dependency on RNA splicing factors whose loss preferentially enhances response to the BCL2 inhibitor venetoclax. Loss of the splicing factor RBM10 augments response to venetoclax in leukemia yet is completely dispensable for normal hematopoiesis. Combined RBM10 and BCL2 inhibition leads to mis-splicing and inactivation of the inhibitor of apoptosis XIAP and downregulation of BCL2A1, an anti-apoptotic protein implicated in venetoclax resistance. Inhibition of splicing kinase families CLKs (CDC-like kinases) and DYRKs (dual-specificity tyrosine-regulated kinases) leads to aberrant splicing of key splicing and apoptotic factors that synergize with venetoclax, and overcomes resistance to BCL2 inhibition. Our findings underscore the importance of splicing in modulating response to therapies and provide a strategy to improve venetoclax-based treatments., Competing Interests: Declaration of interests E.M., E.C., M.J., C.B., C.-C.M., and D.M.B. are employees of Biosplice Therapeutics. O.A.-W. has served as a consultant for H3B Biomedicine, Foundation Medicine Inc., Merck, Prelude Therapeutics, and Janssen and is on the Scientific Advisory Board of Envisagenics Inc., AIChemy, Harmonic Discovery Inc., and Pfizer Boulder. O.A.-W. has received prior research funding from H3B Biomedicine, Nurix Therapeutics, and LOXO Oncology unrelated to the current manuscript. The remaining authors declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Inactivation of the Hippo pathway promotes Yap nuclear translocation, enabling execution of a transcriptional program that induces tissue growth. Genetic lesions of Hippo intermediates only identify a minority of cancers with illegitimate YAP activation. Yap has been implicated in resistance to targeted therapies, but the mechanisms by which YAP may impact adaptive resistance to MAPK inhibitors are unknown., Methods: We screened 52 thyroid cancer cell lines for illegitimate nuclear YAP localization by immunofluorescence and fractionation of cell lysates. We engineered a doxycycline (dox)-inducible thyroid-specific mouse model expressing constitutively nuclear YAP S127A , alone or in combination with endogenous expression of either Hras G12V or Braf V600E . We also generated cell lines expressing dox-inducible sh-miR-E-YAP and/or YAP S127A . We used cell viability, invasion assays, immunofluorescence, Western blotting, qRT-PCRs, flow cytometry and cell sorting, high-throughput bulk RNA sequencing and in vivo tumorigenesis to investigate YAP dependency and response of BRAF-mutant cells to vemurafenib., Results: We found that 27/52 thyroid cancer cell lines had constitutively aberrant YAP nuclear localization when cultured at high density (NU-YAP), which rendered them dependent on YAP for viability, invasiveness and sensitivity to the YAP-TEAD complex inhibitor verteporfin, whereas cells with confluency-driven nuclear exclusion of YAP (CYT-YAP) were not. Treatment of BRAF-mutant thyroid cancer cells with RAF kinase inhibitors resulted in YAP nuclear translocation and activation of its transcriptional output. Resistance to vemurafenib in BRAF-mutant thyroid cells was driven by YAP-dependent NRG1, HER2 and HER3 activation across all isogenic human and mouse thyroid cell lines tested, which was abrogated by silencing YAP and relieved by pan-HER kinase inhibitors. YAP activation induced analogous changes in BRAF melanoma, but not colorectal cells., Conclusions: YAP activation in thyroid cancer generates a dependency on this transcription factor. YAP governs adaptive resistance to RAF kinase inhibitors and induces a gene expression program in BRAF V600E -mutant cells encompassing effectors in the NRG1 signaling pathway, which play a central role in the insensitivity to MAPK inhibitors in a lineage-dependent manner. HIPPO pathway inactivation serves as a lineage-dependent rheostat controlling the magnitude of the adaptive relief of feedback responses to MAPK inhibitors in BRAF- V600E cancers., (© 2022. The Author(s).)

Accurate ancestry inference is critical for identifying genetic contributors of cancer disparities among populations. Although methods to infer genetic ancestry have historically relied upon genome-wide markers, the adaptation to targeted clinical sequencing panels presents an opportunity to incorporate ancestry inference into routine diagnostic workflows. We show that global ancestral contributions and admixture of continental populations can be quantitatively inferred using markers captured by the MSK-IMPACT clinical panel. In a pan-cancer cohort of 45,157 patients, we observed differences by ancestry in the frequency of somatic alterations, recapitulating known associations and revealing novel associations. Despite the comparable overall prevalence of driver alterations by ancestry group, the proportion of patients with clinically actionable alterations was lower for African (30%) compared with European (33%) ancestry. Although this result is largely explained by population-specific cancer subtype differences, it reveals an inequity in the degree to which different populations are served by existing precision oncology interventions., Significance: We performed a comprehensive analysis of ancestral associations with somatic mutations in a real-world pan-cancer cohort, including >5,000 non-European individuals. Using an FDA-authorized tumor sequencing panel and an FDA-recognized oncology knowledge base, we detected differences in the prevalence of clinically actionable alterations, potentially contributing to health care disparities affecting underrepresented populations. This article is highlighted in the In This Issue feature, p. 2483., (©2022 American Association for Cancer Research.)

Papillary thyroid carcinoma (PTC) is the most frequent histological subtype of thyroid cancers (TC), and BRAF V600E genetic alteration is found in 60% of this endocrine cancer. This oncogene is associated with poor prognosis, resistance to radioiodine therapy, and tumor progression. Histological follow-up by anatomo-pathologists revealed that two-thirds of surgically-removed thyroids do not present malignant lesions. Thus, continued fundamental research into the molecular mechanisms of TC downstream of BRAF V600E remains central to better understanding the clinical behavior of these tumors. To study PTC, we used a mouse model in which expression of BRAF V600E was specifically switched on in thyrocytes by doxycycline administration. Upon daily intraperitoneal doxycycline injection, thyroid tissue rapidly acquired histological features mimicking human PTC. Transcriptomic analysis revealed major changes in immune signaling pathways upon BRAF V600E induction. Multiplex immunofluorescence confirmed the abundant recruitment of macrophages, among which a population of LYVE-1+/CD206+/STABILIN-1+ was dramatically increased. By genetically inactivating the gene coding for the scavenger receptor STABILIN-1, we showed an increase of CD8+ T cells in this in situ BRAF V600E -dependent TC. Lastly, we demonstrated the presence of CD206+/STABILIN-1+ macrophages in human thyroid pathologies. Altogether, we revealed the recruitment of immunosuppressive STABILIN-1 macrophages in a PTC mouse model and the interest to further study this macrophage subpopulation in human thyroid tissues.

Hürthle cell carcinomas (HCCs) display two exceptional genotypes: near-homoplasmic mutation of mitochondrial DNA (mtDNA) and genome-wide loss of heterozygosity (gLOH). To understand the phenotypic consequences of these genetic alterations, we analyzed genomic, metabolomic, and immunophenotypic data of HCC and other thyroid cancers. Both mtDNA mutations and profound depletion of citrate pools are common in HCC and other thyroid malignancies, suggesting that thyroid cancers are broadly equipped to survive tricarboxylic acid cycle impairment, whereas metabolites in the reduced form of NADH-dependent lysine degradation pathway were elevated exclusively in HCC. The presence of gLOH was not associated with metabolic phenotypes but rather with reduced immune infiltration, indicating that gLOH confers a selective advantage partially through immunosuppression. Unsupervised multimodal clustering revealed four clusters of HCC with distinct clinical, metabolomic, and microenvironmental phenotypes but overlapping genotypes. These findings chart the metabolic and microenvironmental landscape of HCC and shed light on the interaction between genotype, metabolism, and the microenvironment in cancer.

Purpose: Selumetinib can increase radioactive iodine (RAI) avidity in RAI-refractory tumors. We investigated whether selumetinib plus adjuvant RAI improves complete remission (CR) rates in patients with differentiated thyroid cancer (DTC) at high risk of primary treatment failure versus RAI alone., Methods: ASTRA (ClinicalTrials.gov identifier: NCT01843062) is an international, phase III, randomized, placebo-controlled, double-blind trial. Patients with DTC at high risk of primary treatment failure (primary tumor > 4 cm; gross extrathyroidal extension outside the thyroid gland [T4 disease]; or N1a/N1b disease with ≥ 1 metastatic lymph node(s) ≥ 1 cm or ≥ 5 lymph nodes [any size]) were randomly assigned 2:1 to selumetinib 75 mg orally twice daily or placebo for approximately 5 weeks (no stratification). On treatment days 29-31, recombinant human thyroid-stimulating hormone (0.9 mg)-stimulated RAI ( 131 I; 100 mCi/3.7 GBq) was administered, followed by 5 days of selumetinib/placebo. The primary end point (CR rate 18 months after RAI) was assessed in the intention-to-treat population., Results: Four hundred patients were enrolled (August 27, 2013-March 23, 2016) and 233 randomly assigned (selumetinib, n = 155 [67%]; placebo, n = 78 [33%]). No statistically significant difference in CR rate 18 months after RAI was observed (selumetinib n = 62 [40%]; placebo n = 30 [38%]; odds ratio 1.07 [95% CI, 0.61 to 1.87]; P = .8205). Treatment-related grade ≥ 3 adverse events were reported in 25/154 patients (16%) with selumetinib and none with placebo. The most common adverse event with selumetinib was dermatitis acneiform (n = 11 [7%]). No treatment-related deaths were reported., Conclusion: Postoperative pathologic risk stratification identified patients with DTC at high risk of primary treatment failure, although the addition of selumetinib to adjuvant RAI failed to improve the CR rate for these patients. Future strategies should focus on tumor genotype-tailored drug selection and maintaining drug dosing to optimize RAI efficacy., Competing Interests: Alan L. HoConsulting or Advisory Role: Bristol Myers Squibb, Eisai, Genzyme, Merck, Novartis, Sun Pharma, Eisai, Regeneron, TRM Oncology, Ayala Pharmaceuticals, AstraZeneca, Sanofi, CureVac, Prelude Therapeutics, Kura Oncology, McGivney Global Advisors, Rgenta, AffyImmune Therapeutics, Exelixis, Cellestia, InxmedSpeakers’ Bureau: Medscape, Omniprex America, NovartisResearch Funding: Lilly, Genentech/Roche (Inst), AstraZeneca, Allos Therapeutics, Astellas Pharma, Ayala Pharmaceuticals, Bayer, Bristol Myers Squibb, Daiichi Sankyo, Eisai, Elevar Therapeutics, Kolltan Pharmaceuticals, Kura Oncology, Merck, Novartis, PfizerTravel, Accommodations, Expenses: Janssen Oncology, Merck, Kura Oncology, Ignyta, Ayala Pharmaceuticals, Klusa Pharma Marek DedecjusHonoraria: Sanofi/Aventis, Bayer, Berlin-ChemieResearch Funding: AstraAzeneca/Merck, Exelixis Lori J. WirthConsulting or Advisory Role: Merck, Loxo, Blueprint Medicines, Eisai, Lilly, Bayer, ExelixisResearching Funding: Checkmate Pharmaceuticals (Inst), Lilly (Inst), Ayala Pharmaceuticals (Inst), Eisai (Inst)Expert Testimony: EisaiOther Relationship: PDS Biotechnology R. Michael TuttleResearch Funding: Elesta (Inst) Fernanda VaismanConsulting or Advisory Role: AstraZeneca/Merck, Ipsen, Lilly, Bayer HealthSpeaker’s Bureau: Bayer, AstraZeneca/Merck, Sanofi, United Medical Lars BastholtResearch Funding: Bristol Myers Squibb (Inst) Andrew G. GianoukakisConsulting or Advisory Role: Eisai, Exelixs Patrice RodienConsulting or Advisory Role: Eisai EuropeResearch Funding: Pfizer (Inst) Ralf PaschkeConsulting or Advisory Role: Bayer, EisaiResearching Funding: Bayer (Inst)Patents, Royalties, Other Intellectual Property: Licensing fee for a diagnostic testRossella EliseiConsulting or Advisory Role: EISAI, Genezyme, Loxo, Ipsen, Bayer, Lilly Karen SoEmployment: AstraZenecaStock and Other Ownership Interests: AstraZeneca Danielle CarrollEmployment: AstraZeneca/MedImmune, Azeria therapeutics (I)Leadership: Azeria therapeutics (I)Stock and Other Ownership Interests: AstraZeneca/MedImmune, Azeria Therapeutics (I)Honoraria: AstraZeneca (I)Consulting or Advisory Role: Azeria therapeutics (I)Research Funding: AstraZeneca (I)Patents, Royalties, Other Intellectual Property: Royalties from Active Motif (I), Compositions featuring an attenuated Newcastle disease virus and methods of use for treating neoplasia, Anti-cxc chemokine-2 binding molecules and uses thereof Tina HoveyEmployment: PhastarConsulting or Advisory Role: AstraZenecaResearch Funding: AstraZeneca James A. FaginHonoraria: Eisai EuropeConsulting or Advisory Role: Loxo OncologyPatents, Royalties, Other Intellectual Property: 3. MSK Ref. SK 2014-024-03 Title: Treatment of H-RAS-Driven Tumors. Application Number: 15/305,788. 3. Anti-TSHR Multispecific Antibodies and Uses Thereof, provisional patent.No other potential conflicts of interest were reported.

Purpose: The development of the selective RET inhibitors selpercatinib and pralsetinib has revolutionized the treatment of metastatic progressive RET-mutant medullary thyroid carcinoma (MTC) and other RET-driven cancers, given their more favorable side-effect profile. The aim of this study is to investigate the mechanisms of selpercatinib-induced thyroid dysfunction in athyreotic patients with RET-mutant MTC and in patients with RET-mutant non-small-cell lung cancer (NSCLC) who had a functional thyroid., Materials and Methods: Thyroid hormone levels were evaluated in an observational cohort of five athyreotic patients with MTC and 30 patients with NSCLC before and after initiation of selpercatinib. In vitro experiments to identify the mechanism of selpercatinib-induced thyroid dysfunction were conducted in cells expressing endogenous D1, D2, and D3 iodothyronine deiodinases., Results: Upon initiating treatment with selpercatinib, athyreotic patients developed clinical hypothyroidism with approximately 60% lower T3 levels despite adequate levothyroxine supplementation, whereas in patients with NSCLC, who retain a normal thyroid, selpercatinib resulted in a more attenuated reduction in serum T3, which was dose-dependent. We conducted studies in cells endogenously expressing either D1, D2, or D3, the three iodothyronine deiodinases. Selpercatinib inhibited D2-mediated T3 production in MSTO-211 cells by 50%. A modest repression of D2 mRNA was present in human thyroid cancer TT cells that express RET, but not in the MSTO-211 cells that do not. No effect of the drug was observed on D1 (activating deiodinase) or D3 (inactivating deiodinase). Thus, a nontranscriptional effect of selpercatinib on D2 activity is the most plausible explanation for the low T3 levels., Conclusion: An off-target effect of selpercatinib on D2-mediated T3 production leads to clinical hypothyroidism, primarily in levothyroxine-treated athyreotic patients. Liothyronine supplementation was needed to achieve normal T3 levels and restore clinical euthyroidism., Competing Interests: Eric ShermanConsulting or Advisory Role: Eisai, UpToDate, Lilly, Blueprint Medicines, ExelixisResearch Funding: Plexxikon (Inst), Regeneron (Inst), Lilly (Inst), HUTCHMED (Inst), Novartis (Inst) Charles M. RudinConsulting or Advisory Role: Harpoon Therapeutics, Genentech/Roche, AstraZeneca, Ipsen, Bridge Medicines, Syros Pharmaceuticals, Amgen, Jazz Pharmaceuticals, Epizyme, Syros Pharmaceuticals, Earli, AbbVie, Daiichi Sankyo/UCB Japan, Kowa, MerckResearch Funding: Merck (Inst), Roche/Genentech (Inst)Open Payments Link: https://openpaymentsdata.cms.gov/physician/111056 Alexander DrilonStock and Other Ownership Interests: Treeline BiosciencesHonoraria: Pfizer, Loxo/Bayer/Lilly, IASLC, Helsinn Therapeutics, BeiGene, Remedica, TP Therapeutics, Verastem, Ignyta/Genetech/Roche, AstraZeneca, Liberum, Lungevity, NIH, PER, OncLive/MJH Life Sciences, Clinical Care Options/NCCN, Lung Cancer Research Foundation, Associazione Italiana Oncologia Toracica (AIOT), Chugai Pharma, Sirio Libanes Hospital, Answers in CME, Research to Practice, RV MoreConsulting or Advisory Role: Ignyta, Loxo, AstraZeneca, Pfizer, Blueprint Medicines, Genentech/Roche, BeiGene, Hengrui Therapeutics, Exelixis, Bayer, Tyra Biosciences, Takeda/Millennium, BerGenBio, MORE Health, Lilly, AbbVie, 14ner Oncology/Elevation Oncology, Monopteros Therapeutics, Novartis, EMD Serono/Merck, Repare Therapeutics, Melendi, Archer, Nuvalent, Inc, Janssen, Amgen, Merus, Axis Pharma, Medscape, Liberum, Med Learning, PeerView, EPG Health, Journal of the National Comprehensive Cancer Network, Ology Medical Education, Clinical Care Options, touchIME, Entos, Prelude Therapeutics, Applied Pharmaceutical Science, Treeline BioResearch Funding: Foundation MedicinePatents, Royalties, Other Intellectual Property: Wolters Kluwer (Royalties for Pocket Oncology)Other Relationship: Merck, GlaxoSmithKline, Teva, Taiho Pharmaceutical, Pfizer, PharmaMar, Puma Biotechnology, Merus, Boehringer Ingelheim Antonio C. BiancoConsulting or Advisory Role: AbbVie, Allergan, Syntonics, Sention, Thyron James A. FaginHonoraria: Eisai EuropeConsulting or Advisory Role: LoxoPatents, Royalties, Other Intellectual Property: 3. MSK Ref. SK 2014-024-03 Title: Treatment of H-RAS-Driven Tumors. Application Number: 15/305,788, Anti-TSHR Multispecific Antibodies and Uses Thereof. Provisional patent (Inst)No other potential conflicts of interest were reported.

Purpose: Anaplastic thyroid carcinoma (ATC) is the most lethal form of thyroid cancer with most patients dying of their disease within a few months. Only a very small percentage of long-term survivors (LTS) are alive for 2 years or longer. In this retrospective case-control study, we provided a comprehensive comparison between 46 ATC LTSs and 75 ATC control patients who suffered disease-specific mortality within 2 years, aiming to identify factors that may be associated with prolonged survival in ATC., Methods: A comprehensive clinicopathologic and molecular comparison was performed between 46 ATC LTSs and 75 ATC control patients. Peripheral neutrophil count and neutrophil-to-lymphocyte ratio (NLR) were recorded. The composition of the tumor microenvironment was compared using immunohistochemistry., Results: Compared with ATC control patients, ATC LTSs were characterized by 1) higher frequency of (primary) resection as well as clinicopathologic parameters attributed to resectability; 2) lower rate of concurrent RAS/BRAF and TERT promoter mutations; 3) lower peripheral neutrophil count and NLR; and 4) lower number of tumor-infiltrating neutrophils/myeloid-derived suppressor cells (MDSC). The survival benefits of low peripheral neutrophil counts and low NLR persisted even when controlling for distant metastasis status at presentation., Conclusions: In addition to traditional beneficial prognostic factors, e.g., surgical resection, factors attributed to resectability, and absence of co-existing RAS/BRAF and TERT promoter mutations, we herein show that tumor-infiltrating and circulating neutrophils/MDSC are adverse prognostic factors in ATC., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: The development of systemic treatment options leveraging the molecular landscape of advanced thyroid cancer is a burgeoning field. This is a multidisciplinary evidence-based statement on the definition of advanced thyroid cancer and its targeted systemic treatment., Methods: An expert panel was assembled, a literature review was conducted, and best practice statements were developed. The modified Delphi method was applied to assess the degree of consensus for the statements developed by the author panel., Results: A review of the current understanding of thyroid oncogenesis at a molecular level is presented and characteristics of advanced thyroid cancer are defined. Twenty statements in topics including the multidisciplinary management, molecular evaluation, and targeted systemic treatment of advanced thyroid cancer are provided., Conclusions: With the growth in targeted treatment options for thyroid cancer, a consensus definition of advanced disease and statements regarding the utility of molecular testing and available targeted systemic therapy is warranted., (© 2022 Wiley Periodicals LLC.)

Competing Interests: James A. FaginHonoraria: Eisai EuropeConsulting or Advisory Role: Loxo OncologyPatents, Royalties, Other Intellectual Property: MSK Ref. SK 2014-024-03 Title: Treatment of H-RAS–Driven Tumors. Application Number: 15/305,788, Anti-TSHR Multispecific Antibodies and Uses Thereof. Provisional patent (Inst)No other potential conflicts of interest were reported.

Context: The BRAFV600E mutation has been associated with more advanced clinical stage in papillary thyroid cancer (PTC) and decreased responsiveness to radioiodine (RAI). However, some BRAF mutant PTCs respond to RAI and have an indolent clinical behavior suggesting the presence of different subtypes of BRAF mutant tumors with distinct prognosis., Objective: To characterize the molecular and clinical features of 2 subtypes of BRAF-mutant PTCs defined by their degree of expression of iodine metabolism genes., Design: 227 BRAF-mutant PTCs from the Cancer Genome Atlas Thyroid Cancer study were divided into 2 subgroups based on their thyroid differentiation score (TDS): BRAF-TDShi and BRAF-TDSlo. Demographic, clinico-pathological, and molecular characteristics of the 2 subgroups were compared., Results: Compared to BRAF-TDShi tumors (17%), BRAF-TDSlo tumors (83%) were more frequent in blacks and Hispanics (6% vs 0%, P = 0.035 and 12% vs 0%, P = 0.05, respectively), they were larger (2.95 ± 1.7 vs 2.03 ± 1.5, P = 0.002), with more tumor-involved lymph nodes (3.9 ± 5.8 vs 2.0 ± 4.2, P = 0.042), and a higher frequency of distant metastases (3% vs 0%, P = 0.043). Gene set enrichment analysis showed positive enrichment for RAS signatures in the BRAF-TDShi cohort, with corresponding reciprocal changes in the BRAF-TDSlo group. Several microRNAs (miRs) targeting nodes in the transforming growth factor β (TGFβ)-SMAD pathway, miR-204, miR-205, and miR-144, were overexpressed in the BRAF-TDShi group. In the subset with follow-up data, BRAF-TDShi tumors had higher complete responses to therapy (94% vs 57%, P < 0.01) than BRAF-TDSlo tumors., Conclusion: Enrichment for RAS signatures, key genes involved in cell polarity and specific miRs targeting the TGFβ-SMAD pathway define 2 subtypes of BRAF-mutant PTCs with distinct clinical characteristics and prognosis., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Papillary thyroid cancer (PTC) is the most common endocrine malignancy for which diagnosis and recurrences still challenge clinicians. New perspectives to overcome these issues could come from the study of extracellular vesicle (EV) populations and content. Here, we aimed to elucidate the heterogeneity of EVs circulating in the tumor and the changes in their microRNA content during cancer progression. Using a mouse model expressing BRAF V600E , we isolated and characterized EVs from thyroid tissue by ultracentrifugations and elucidated their microRNA content by small RNA sequencing. The cellular origin of EVs was investigated by ExoView and that of deregulated EV-microRNA by qPCR on FACS-sorted cell populations. We found that PTC released more EVs bearing epithelial and immune markers, as compared to the healthy thyroid, so that changes in EV-microRNAs abundance were mainly due to their deregulated expression in thyrocytes. Altogether, our work provides a full description of in vivo-derived EVs produced by, and within, normal and cancerous thyroid. We elucidated the global EV-microRNAs signature, the dynamic loading of microRNAs in EVs upon BRAF V600E induction, and their cellular origin. Finally, we propose that thyroid tumor-derived EV-microRNAs could support the establishment of a permissive immune microenvironment.

Background: Oncogenic activation of mitogen-activated protein kinase (MAPK) signaling is associated with radioiodine refractory (RAIR) thyroid cancer. Preclinical models suggest that activation of the receptor tyrosine kinase erbB-3 (HER3) mitigates the MAPK pathway inhibition achieved by BRAF inhibitors in BRAF V600E mutant thyroid cancers. We hypothesized that combined inhibition of BRAF and HER3 using vemurafenib and the human monoclonal antibody CDX-3379, respectively, would potently inhibit MAPK activation and restore radioactive iodine (RAI) avidity in patients with BRAF- mutant RAIR thyroid cancer. Methods: Patients with BRAF V600E RAIR thyroid cancer were evaluated by thyrogen-stimulated iodine-124 ( 124 I) positron emission tomography-computed tomography (PET/CT) at baseline and after 5 weeks of treatment with oral vemurafenib 960 mg twice daily alone for 1 week, followed by vemurafenib in combination with 1000 mg of intravenous CDX-3379 every 2 weeks. Patients with adequate 124 I uptake on the second PET/CT then received therapeutic radioactive iodine ( 131 I) with vemurafenb+CDX-3379. All therapy was discontinued two days later. Treatment response was monitored by serum thyroglobulin measurements and imaging. The primary endpoints were safety and tolerability of vemurafenib+CDX-3379, as well as the proportion of patients after vemurafenb+CDX-3379 therapy with enhanced RAI incorporation warranting therapeutic 131 I. Results: Seven patients were enrolled; six were evaluable for the primary endpoints. No grade 3 or 4 toxicities related to CDX-3379 were observed. Five patients had increased RAI uptake after treatment; in 4 patients this increased uptake warranted therapeutic 131 I. At 6 months, 2 patients achieved partial response after 131 I and 2 progression of disease. Next-generation sequencing of 5 patients showed that all had co-occurring telomerase reverse transcriptase promoter alterations. A deleterious mutation in the SWItch/Sucrose Non-Fermentable (SWI/SNF) gene ARID2 was discovered in the patient without enhanced RAI avidity after therapy and an RAI-resistant tumor from another patient that was sampled off-study. Conclusions: The endpoints for success were met, providing preliminary evidence of vemurafenib+CDX-3379 safety and efficacy for enhancing RAI uptake. Preclinical data and genomic profiling in this small cohort suggest SWI/SNF gene mutations should be investigated as potential markers of resistance to redifferentiation strategies. Further evaluation of vemurafenib+CDX-3379 as a redifferentiation therapy in a larger trial is warranted (ClinicalTrials.gov: NCT02456701).

Hurthle cell carcinomas (HCCs) are refractory to radioactive iodine and unresponsive to chemotherapeutic agents, with a fatality rate that is the highest among all types of thyroid cancer after anaplastic thyroid cancer. Our previous study on the genomic landscape of HCCs identified a high incidence of disruptions of mTOR pathway effectors. Here, we report a detailed analysis of mTOR signaling in cell line and patient-derived xenograft mouse models of HCCs. We show that mTOR signaling is upregulated and that targeting mTOR signaling using mTOR inhibitors suppresses tumor growth in primary tumors and distant metastasis. Mechanistically, ablation of mTOR signaling impaired the expression of p-S6 and cyclin A2, resulting in the decrease of the S phase and blocking of cancer cell proliferation. Strikingly, mTOR inhibitor treatment significantly reduced lung metastatic lesions, with the decreased expression of Snail in xenograft tumors. Our data demonstrate that mTOR pathway blockade represents a novel treatment strategy for HCC., (©2021 American Association for Cancer Research.)

Aims: We aimed to study the clinicopathological and molecular features of high-grade non-anaplastic thyroid carcinomas (HGTCs), a carcinoma with a prognosis intermediate between those of well-differentiated carcinoma and anaplastic carcinoma., Methods and Results: This study included 364 HGTC patients: 200 patients (54.9%) were diagnosed with poorly differentiated thyroid carcinoma (PDTC), based on the Turin consensus (HGTC-PDTC), and 164 were diagnosed with high-grade features that did not meet the Turin criteria (HGTC-nonPDTC). HGTCs are aggressive: the 3-year, 5-year, 10-year and 20-year disease-specific survival (DSS) rates were 89%, 76%, 60%, and 35%, respectively. Although DSS was similar between HGTC-PDTC and HGTC-nonPDTC patients, HGTC-PDTC was associated with higher rate of radioactive iodine avidity, a higher frequency of RAS mutations, a lower frequency of BRAF V600E mutations and a higher propensity for distant metastasis (DM) than HGTC-nonPDTC. Independent clinicopathological markers of worse outcome were: older age, male sex, extensive necrosis and lack of encapsulation for DSS; older age, male sex and vascular invasion for DM-free survival; and older age, necrosis, positive margins and lymph node metastasis for locoregional recurrence-free survival. The frequencies of BRAF, RAS, TERT, TP53 and PTEN alterations were 28%, 40%, 55%, 11%, and 10%, respectively. TP53, PTEN and TERT were independent molecular markers associated with an unfavourable outcome, independently of clinicopathological parameters. The coexistence of BRAF V600E and TERT promoter mutation increased the risk of DM., Conclusions: The above data support the classification of HGTC as a single group with two distinct subtypes based on tumour differentiation: HGTC-PDTC and HGTC-nonPDTC., (© 2021 John Wiley & Sons Ltd.)

Targeted inhibition of BRAF V600E achieves tumor control in a subset of advanced thyroid tumors. Nearly all tumors develop resistance, and some have been observed to subsequently undergo dedifferentiation. The molecular alterations associated with thyroid cancer dedifferentiation in the setting of BRAF inhibition are unknown. We analyzed targeted next-generation sequencing data from 639 advanced, recurrent and/or metastatic thyroid carcinomas, including 15 tumors that were treated with BRAF inhibitor drugs and had tissue sampled during or posttreatment, 8 of which had matched pretherapy samples. Pre- and posttherapy tissues from one additional patient were profiled with whole-exome sequencing and RNA expression profiling. Mutations in genes comprising the SWI/SNF chromatin remodeling complex and the PI3K-AKT-mTOR, MAPK, and JAK-STAT pathways all increased in prevalence across more dedifferentiated thyroid cancer histologies. Of 7 thyroid cancers that dedifferentiated after BRAF inhibition, 6 had mutations in these pathways. These mutations were mostly absent from matched pretreatment samples and were rarely detected in tumors that did not dedifferentiate. Additional analyses in one of the vemurafenib-treated tumors before and after anaplastic transformation revealed the emergence of an oncogenic PIK3CA mutation, activation of ERK signaling, dedifferentiation, and development of an immunosuppressive tumor microenvironment. These findings validate earlier preclinical data implicating these genetic pathways in resistance to BRAF inhibitors, and suggest that genetic alterations mediating acquired drug resistance may also promote thyroid tumor dedifferentiation. IMPLICATIONS: The possibility that thyroid cancer dedifferentiation may be attributed to selective pressure applied by BRAF inhibitor-targeted therapy should be investigated further., (©2021 American Association for Cancer Research.)

Purpose: Medullary thyroid carcinoma (MTC) is an aggressive neuroendocrine tumor (NET) arising from the calcitonin-producing C cells. Unlike other NETs, there is no widely accepted pathologic grading scheme. In 2020, two groups separately developed slightly different schemes (the Memorial Sloan Kettering Cancer Center and Sydney grade) on the basis of proliferative activity (mitotic index and/or Ki67 proliferative index) and tumor necrosis. Building on this work, we sought to unify and validate an internationally accepted grading scheme for MTC., Patients and Methods: Tumor tissue from 327 patients with MTC from five centers across the United States, Europe, and Australia were reviewed for mitotic activity, Ki67 proliferative index, and necrosis using uniform criteria and blinded to other clinicopathologic features. After reviewing different cutoffs, a two-tiered consensus grading system was developed. High-grade MTCs were defined as tumors with at least one of the following features: mitotic index ≥ 5 per 2 mm 2 , Ki67 proliferative index ≥ 5%, or tumor necrosis., Results: Eighty-one (24.8%) MTCs were high-grade using this scheme. In multivariate analysis, these patients demonstrated decreased overall (hazard ratio [HR] = 11.490; 95% CI, 3.118 to 32.333; P < .001), disease-specific (HR = 8.491; 95% CI, 1.461 to 49.327; P = .017), distant metastasis-free (HR = 2.489; 95% CI, 1.178 to 5.261; P = .017), and locoregional recurrence-free (HR = 2.114; 95% CI, 1.065 to 4.193; P = .032) survivals. This prognostic power was maintained in subgroup analyses of cohorts from each of the five centers., Conclusion: This simple two-tiered international grading system is a powerful predictor of adverse outcomes in MTC. As it is based solely on morphologic assessment in conjunction with Ki67 immunohistochemistry, it brings the grading of MTCs in line with other NETs and can be readily applied in routine practice. We therefore recommend grading of MTCs on the basis of mitotic count, Ki67 proliferative index, and tumor necrosis., Competing Interests: Eric BaudinConsulting or Advisory Role: Ipsen, Novartis, AAA HealthCare, Pfizer, Hutchison MediPharmaResearch Funding: Pfizer (Inst), Novartis (Inst), HRA Pharma (Inst) James A. FaginConsulting or Advisory Role: Loxo OncologyPatents, Royalties, Other Intellectual Property: 3. MSK Ref. SK 2014-024-03 Title: Treatment of H-RAS-Driven Tumors. Application Number: 15/305,788 Dana HartlConsulting or Advisory Role: Medtronic Fedaa NajdawiEmployment: PathAINo other potential conflicts of interest were reported.

Background: The use of external-beam radiotherapy for locally advanced nonanaplastic thyroid cancer remains controversial. This prospective study evaluated the efficacy and tolerability of intensity-modulated radiation therapy (IMRT) with or without concurrent chemotherapy in patients with locally advanced thyroid cancer., Methods: The authors conducted a nonrandomized phase 2 trial of IMRT with or without concurrent doxorubicin in patients with gross residual or unresectable nonanaplastic thyroid carcinoma (ClinicalTrials.gov identifier NCT01882816). The primary end point was 2-year locoregional progression-free survival (PFS). Secondary end points included overall survival (OS), safety, patient-reported outcomes, and functional outcomes., Results: Twenty-seven patients were enrolled: 12 (44.4%) with unresectable disease and 15 (55.6%) with gross residual disease. The median follow-up was 45.6 months (interquartile range, 42.0-51.6 months); the 2-year cumulative incidences of locoregional PFS and OS were 79.7% and 77.3%, respectively. The rate of grade 3 or higher acute and late toxicities was 33.4%. There were no significant functional differences 12 months after treatment (assessed objectively by the modified barium swallow study). Patient-reported quality of life in the experimental group was initially lower but returned to the baseline after 6 months and improved thereafter. In a post hoc analysis, concurrent chemotherapy with intensity-modulated radiation therapy (CC-IMRT) resulted in significantly less locoregional failure at 2 years (no failure vs 50%; P = .001), with higher rates of grade 2 or higher acute dermatitis, mucositis, and dysphagia but no difference in long-term toxicity, functionality, or patient-reported quality of life., Conclusions: In light of the excellent locoregional control rates achieved with CC-IMRT and its acceptable toxicity profile as confirmed by functional assessments and patient-reported outcomes, CC-IMRT may be preferred over IMRT alone., (© 2021 American Cancer Society.)

Background: To compare laser ablation (LA) zone dimensions at two predetermined energy parameters to cover a theoretical 10 mm zone + 2 mm margin in a thyroid swine model., Methods: Approval of the Institutional Animal Care and Use Committee was obtained. After hydrodissection, an ultrasound-guided LA (Elesta Echolaser X4 with Orblaze technology, 1064 nm) was performed in the periphery of the thyroid in 10 swine. Two cohorts were established to ablate a region of 10mm diameter with 2mm margin based on manufacturer's ex vivo data (n= 5 at 3W/1400J and n= 5 at 3W/1800J). The ablation zone was measured on contrast-enhanced computed tomography (CT) and compared to the pathological specimen. Euthanasia was performed 48 hours following ablation., Results: All ablations in the 3W/1800J group achieved a diameter of 12 mm ± 1 mm in three dimensions. In the 3W/1400J group, 1 ablation reached 12 mm ± 1 mm in 2 dimensions and 4 ablations reached this size in one dimension. Maximum diameter was higher in the 3W/1800J compared to the 3W/1400J group, both on histology (1.46 cm ± 0.05 vs. 1.1 cm ± 0.0, p< 0.01) and CT (1.52 cm ± 0.04 vs. 1.18 cm ± 0.04, p< 0.01). Similar results were obtained regarding volumes, both on histology (1.12 mL ± 0.13 vs. 0.57 mL ± 0.06, p< 0.01) and CT (1.24 mL ± 0.13 vs. 0.59 mL ± 0.07, p< 0.01). Histology showed coagulation necrosis and correlated well with CT measurements., Conclusion: Optimal parameters to obtain a LA zone of 10 mm with 2 mm margin utilizing a single needle are 3W/1800J., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).)

A prototypic pediatric cancer that frequently shows activation of RAS signaling is embryonal rhabdomyosarcoma (ERMS). ERMS also show aberrant Hedgehog (HH)/GLI signaling activity and can be driven by germline mutations in this pathway. We show, that in ERMS cell lines derived from sporadic tumors i.e. from tumors not caused by an inherited genetic variant, HH/GLI signaling plays a subordinate role, because oncogenic mutations in HRAS, KRAS, or NRAS (collectively named oncRAS) inhibit the main HH target GLI1 via the MEK/ERK-axis, but simultaneously increase proliferation and tumorigenicity. oncRAS also modulate expression of stem cell markers in an isoform- and context-dependent manner. In Hh-driven murine ERMS that are caused by a Patched mutation, oncHRAS and mainly oncKRAS accelerate tumor development, whereas oncNRAS induces a more differentiated phenotype. These features occur when the oncRAS mutations are induced at the ERMS precursor stage, but not when induced in already established tumors. Moreover, in contrast to what is seen in human cell lines, oncRAS mutations do not alter Hh signaling activity and marginally affect expression of stem cell markers. Together, all three oncRAS mutations seem to be advantageous for ERMS cell lines despite inhibition of HH signaling and isoform-specific modulation of stem cell markers. In contrast, oncRAS mutations do not inhibit Hh-signaling in Hh-driven ERMS. In this model, oncRAS mutations seem to be advantageous for specific ERMS populations that occur within a specific time window during ERMS development. In addition, this window may be different for individual oncRAS isoforms, at least in the mouse., (© 2021. The Author(s).)

Constitutive MAPK activation silences genes required for iodide uptake and thyroid hormone biosynthesis in thyroid follicular cells. Accordingly, most BRAFV600E papillary thyroid cancers (PTC) are refractory to radioiodide (RAI) therapy. MAPK pathway inhibitors rescue thyroid-differentiated properties and RAI responsiveness in mice and patient subsets with BRAFV600E-mutant PTC. TGFB1 also impairs thyroid differentiation and has been proposed to mediate the effects of mutant BRAF. We generated a mouse model of BRAFV600E-PTC with thyroid-specific knockout of the Tgfbr1 gene to investigate the role of TGFB1 on thyroid-differentiated gene expression and RAI uptake in vivo. Despite appropriate loss of Tgfbr1, pSMAD levels remained high, indicating that ligands other than TGFB1 were engaging in this pathway. The activin ligand subunits Inhba and Inhbb were found to be overexpressed in BRAFV600E-mutant thyroid cancers. Treatment with follistatin, a potent inhibitor of activin, or vactosertib, which inhibits both TGFBR1 and the activin type I receptor ALK4, induced a profound inhibition of pSMAD in BRAFV600E-PTCs. Blocking SMAD signaling alone was insufficient to enhance iodide uptake in the setting of constitutive MAPK activation. However, combination treatment with either follistatin or vactosertib and the MEK inhibitor CKI increased 124I uptake compared to CKI alone. In summary, activin family ligands converge to induce pSMAD in Braf-mutant PTCs. Dedifferentiation of BRAFV600E-PTCs cannot be ascribed primarily to activation of SMAD. However, targeting TGFβ/activin-induced pSMAD augmented MAPK inhibitor effects on iodine incorporation into BRAF tumor cells, indicating that these two pathways exert interdependent effects on the differentiation state of thyroid cancer cells.

Mutations of subunits of the SWI/SNF chromatin remodeling complexes occur commonly in cancers of different lineages, including advanced thyroid cancers. Here we show that thyroid-specific loss of Arid1a, Arid2 , or Smarcb1 in mouse BRAF V600E -mutant tumors promotes disease progression and decreased survival, associated with lesion-specific effects on chromatin accessibility and differentiation. As compared with normal thyrocytes, BRAF V600E -mutant mouse papillary thyroid cancers have decreased lineage transcription factor expression and accessibility to their target DNA binding sites, leading to impairment of thyroid-differentiated gene expression and radioiodine incorporation, which is rescued by MAPK inhibition. Loss of individual SWI/SNF subunits in BRAF tumors leads to a repressive chromatin state that cannot be reversed by MAPK pathway blockade, rendering them insensitive to its redifferentiation effects. Our results show that SWI/SNF complexes are central to the maintenance of differentiated function in thyroid cancers, and their loss confers radioiodine refractoriness and resistance to MAPK inhibitor-based redifferentiation therapies. SIGNIFICANCE: Reprogramming cancer differentiation confers therapeutic benefit in various disease contexts. Oncogenic BRAF silences genes required for radioiodine responsiveness in thyroid cancer. Mutations in SWI/SNF genes result in loss of chromatin accessibility at thyroid lineage specification genes in BRAF -mutant thyroid tumors, rendering them insensitive to the redifferentiation effects of MAPK blockade. This article is highlighted in the In This Issue feature, p. 995 ., (©2020 American Association for Cancer Research.)

Growth hormone-secreting (GH-secreting) pituitary tumors are driven by oncogenes that induce cAMP signaling. In this issue of the JCI, Ben-Shlomo et al. performed a whole-exome study of pituitary adenomas. GH-secreting tumors had a high frequency of whole chromosome or chromosome arm copy number alterations and were associated with an increase in the tumor protein p53 and the cyclin-dependent kinase inhibitor p21WAF1/CIP1, which are findings consistent with induction of a response to DNA damage. Further, treatment of mouse pituitary cells with cAMP pathway agonists in vitro and in vivo elicited biomarkers of DNA replication stress or double-strand breaks. The findings of Ben Shlomo et al. indicate that oncoproteins that drive constitutively high cAMP signaling pathway output in susceptible cell types can elicit DNA replication stress and may promote genomic instability.

Background: Anaplastic thyroid carcinoma (ATC) is nearly always fatal. Large studies on ATC are exceedingly rare. We aimed to study the clinical, genotypic, and histologic characteristics of ATC in the largest retrospective cohort of ATC to date. Methods: Three hundred sixty patients with ATC from two tertiary centers were studied. Molecular testing was performed in 126 cases including 107 using next-generation sequencing. Results: The median patients' age was 68 years. Differentiated thyroid carcinoma (DTC) was present in 208 cases (58%), the most common being papillary carcinoma ( n  = 150). The 1-, 2-, 3-, and 5-year overall survival (OS) was 36%, 17%, 13%, and 11%, respectively. On univariate analysis, age, resectability, chemotherapy, radiotherapy, margin status, encapsulation, gross residual disease, gross extrathyroidal extension, percentage, and size of ATC in the primary tumor predicted OS ( p  < 0.05). Age, resectability, chemotherapy, and gross residual disease were independent prognostic factors in the entire cohort, while gross residual disease was the only independent predictor of OS in patients who had resection of their tumor. BRAF , RAS , TERT promoter, TP53 , PIK3CA , E1F1AX , and PTEN mutations were detected in 45%, 24%, 75%, 63%, 18%, 14%, and 14% of ATC, respectively. Concomitant BRAF/RAS and TERT mutations were associated with worse outcome than mutation in only one of the genes. BRAF- mutated and RAS -mutated ATCs had similar frequency of nodal and distant metastasis. Twelve cases were pure squamous cell carcinoma, 60% of which carried BRAF V600E mutation and showed a similar OS to other ATCs. Conclusions: (i) Gross residual disease remains the most crucial indicator of outcome in ATC. (ii) Encapsulation, margin status, percentage, and size of ATC in the primary were prognostically relevant. (iii) Pure thyroid squamous cell carcinoma may be considered as ATC given a BRAF V600E genotype and similar outcome. (iv) In contrast to DTC, BRAF -mutated and RAS -mutated ATCs have similar metastatic spread. (v) Concomitant mutations of BRAF or RAS with TERT confer a worse prognosis.

The purpose of this study was to identify the optimal tracer kinetic model from T 1 -weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data and evaluate whether parameters estimated from the optimal model predict tumor aggressiveness determined from histopathology in patients with papillary thyroid carcinoma (PTC) prior to surgery. In this prospective study, 18 PTC patients underwent pretreatment DCE-MRI on a 3 T MR scanner prior to thyroidectomy. This study was approved by the institutional review board and informed consent was obtained from all patients. The two-compartment exchange model, compartmental tissue uptake model, extended Tofts model (ETM) and standard Tofts model were compared on a voxel-wise basis to determine the optimal model using the corrected Akaike information criterion (AICc) for PTC. The optimal model is the one with the lowest AICc. Statistical analysis included paired and unpaired t-tests and a one-way analysis of variance. Bonferroni correction was applied for multiple comparisons. Receiver operating characteristic (ROC) curves were generated from the optimal model parameters to differentiate PTC with and without aggressive features, and AUCs were compared. ETM performed best with the lowest AICc and the highest Akaike weight (0.44) among the four models. ETM was preferred in 44% of all 3419 voxels. The ETM estimates of K trans in PTCs with the aggressive feature extrathyroidal extension (ETE) were significantly higher than those without ETE (0.78 ± 0.29 vs. 0.34 ± 0.18 min -1 , P = 0.005). From ROC analysis, cut-off values of K trans , v e and v p , which discriminated between PTCs with and without ETE, were determined at 0.45 min -1 , 0.28 and 0.014 respectively. The sensitivities and specificities were 86 and 82% (K trans ), 71 and 82% (v e ), and 86 and 55% (v p ), respectively. Their respective AUCs were 0.90, 0.71 and 0.71. We conclude that ETM K trans has shown potential to classify tumors with and without aggressive ETE in patients with PTC., (© 2019 John Wiley & Sons, Ltd.)

The sodium iodide symporter (NIS) is required for iodide uptake, which facilitates thyroid hormone biosynthesis. NIS has been exploited for over 75 years in ablative radioiodine (RAI) treatment of thyroid cancer, where its ability to transport radioisotopes depends on its localization to the plasma membrane. The advent of NIS-based in vivo imaging and theranostic strategies in other malignancies and disease modalities has recently increased the clinical importance of NIS. However, NIS trafficking remains ill-defined. Here, we used tandem mass spectrometry followed by coimmunoprecipitation and proximity ligation assays to identify and validate two key nodes-ADP-ribosylation factor 4 (ARF4) and valosin-containing protein (VCP)-controlling NIS trafficking. Using cell-surface biotinylation assays and highly inclined and laminated optical sheet microscopy, we demonstrated that ARF4 enhanced NIS vesicular trafficking from the Golgi to the plasma membrane, whereas VCP-a principal component of endoplasmic reticulum (ER)-associated degradation-governed NIS proteolysis. Gene expression analysis indicated VCP expression was particularly induced in aggressive thyroid cancers and in patients who had poorer outcomes following RAI treatment. Two repurposed FDA-approved VCP inhibitors abrogated VCP-mediated repression of NIS function, resulting in significantly increased NIS at the cell-surface and markedly increased RAI uptake in mouse and human thyroid models. Collectively, these discoveries delineate NIS trafficking and highlight the new possibility of systemically enhancing RAI therapy in patients using FDA-approved drugs. SIGNIFICANCE: These findings show that ARF4 and VCP are involved in NIS trafficking to the plasma membrane and highlight the possible therapeutic role of VCP inhibitors in enhancing radioiodine effectiveness in radioiodine-refractory thyroid cancer., (©2019 American Association for Cancer Research.)

Context: Most papillary microcarcinomas (PMCs) are indolent and subclinical. However, as many as 10% can present with clinically significant nodal metastases., Objective and Design: Characterization of the genomic and transcriptomic landscape of PMCs presenting with or without clinically important lymph node metastases., Subjects and Samples: Formalin-fixed paraffin-embedded PMC samples from 40 patients with lateral neck nodal metastases (pN1b) and 71 patients with PMC with documented absence of nodal disease (pN0)., Outcome Measures: To interrogate DNA alterations in 410 genes commonly mutated in cancer and test for differential gene expression using a custom NanoString panel of 248 genes selected primarily based on their association with tumor size and nodal disease in the papillary thyroid cancer TCGA project., Results: The genomic landscapes of PMC with or without pN1b were similar. Mutations in TERT promoter (3%) and TP53 (1%) were exclusive to N1b cases. Transcriptomic analysis revealed differential expression of 43 genes in PMCs with pN1b compared with pN0. A random forest machine learning-based molecular classifier developed to predict regional lymph node metastasis demonstrated a negative predictive value of 0.98 and a positive predictive value of 0.72 at a prevalence of 10% pN1b disease., Conclusions: The genomic landscape of tumors with pN1b and pN0 disease was similar, whereas 43 genes selected primarily by mining the TCGA RNAseq data were differentially expressed. This bioinformatics-driven approach to the development of a custom transcriptomic assay provides a basis for a molecular classifier for pN1b risk stratification in PMC., (Copyright © 2019 Endocrine Society.)

Purpose: Thyroid cancer cell lines are valuable models but have been neglected in pancancer genomic studies. Moreover, their misidentification has been a significant problem. We aim to provide a validated dataset for thyroid cancer researchers., Experimental Design: We performed next-generation sequencing (NGS) and analyzed the transcriptome of 60 authenticated thyroid cell lines and compared our findings with the known genomic defects in human thyroid cancers., Results: Unsupervised transcriptomic analysis showed that 94% of thyroid cell lines clustered distinctly from other lineages. Thyroid cancer cell line mutations recapitulate those found in primary tumors (e.g., BRAF , RAS , or gene fusions). Mutations in the TERT promoter (83%) and TP53 (71%) were highly prevalent. There were frequent alterations in PTEN , PIK3CA , and of members of the SWI/SNF chromatin remodeling complex, mismatch repair, cell-cycle checkpoint, and histone methyl- and acetyltransferase functional groups. Copy number alterations (CNA) were more prevalent in cell lines derived from advanced versus differentiated cancers, as reported in primary tumors, although the precise CNAs were only partially recapitulated. Transcriptomic analysis showed that all cell lines were profoundly dedifferentiated, regardless of their derivation, making them good models for advanced disease. However, they maintained the BRAF V600E versus RAS-dependent consequences on MAPK transcriptional output, which correlated with differential sensitivity to MEK inhibitors. Paired primary tumor-cell line samples showed high concordance of mutations. Complete loss of p53 function in TP53 heterozygous tumors was the most prominent event selected during in vitro immortalization., Conclusions: This cell line resource will help inform future preclinical studies exploring tumor-specific dependencies., (©2019 American Association for Cancer Research.)

Cancer cell lines are critical models to study tumor progression and response to therapy. In 2008, we showed that approximately 50% of thyroid cancer cell lines were redundant or not of thyroid cancer origin. We therefore generated new authenticated thyroid cancer cell lines and patient-derived xenograft (PDX) models using in vitro and feeder cell approaches, and characterized these models in vitro and in vivo . We developed four thyroid cancer cell lines, two derived from 2 different patients with papillary thyroid cancer (PTC) pleural effusions, CUTC5, and CUTC48; one derived from a patient with anaplastic thyroid cancer (ATC), CUTC60; and one derived from a patient with follicular thyroid cancer (FTC), CUTC61. One PDX model (CUTC60-PDX) was also developed. Short tandem repeat (STR) genotyping showed that each cell line and PDX is unique and match the original patient tissue. The CUTC5 and CUTC60 cells harbor the BRAF (V600E) mutation, the CUTC48 cell line expresses the RET/PTC1 rearrangement, and the CUTC61 cells have the HRAS (Q61R) mutation. Moderate to high levels of PAX8 and variable levels of NKX2-1 were detected in each cell line and PDX. The CUTC5 and CUTC60 cell lines form tumors in orthotopic and flank xenograft mouse models. IMPLICATIONS: We have developed the second RET/PTC1-expressing PTC-derived cell line in existence, which is a major advance in studying RET signaling. We have further linked all cell lines to the originating patients, providing a set of novel, authenticated thyroid cancer cell lines and PDX models to study advanced thyroid cancer., (©2019 American Association for Cancer Research.)