Genetic Profiles of Aggressive Variants of Papillary Thyroid Carcinomas

A Critical Assessment of Diagnostic Criteria for the Tall Cell Subtype of Papillary Thyroid Carcinoma-How Much? How Tall? And When Is It Relevant?

Tall cell papillary thyroid carcinoma (TC-PTC) is considered adverse histology. However, previous studies are confounded by inconsistent criteria and strong associations with other adverse features. It is therefore still unclear if TC-PTC represents an independent prognostic factor in multivariate analysis and, if it does, what criteria should be employed for the diagnosis. We retrospectively reviewed 487 PTCs from our institution (where we have historically avoided the prospective diagnosis of TC-PTC) for both the height of tall cells (that is if the cells were two, or three, times as tall as wide) and the percentage of tall cells. On univariate analysis, there was significantly better disease free survival (DFS) in PTCs with no significant tall cell component (< 30%) compared to PTCs with cells two times tall as wide (p = 0.005). The proportion of tall cells (30-50% and > 50%) was significantly associated with DFS (p = 0.012). In a multivariate model including age, size, vascular space invasion, and lymph node metastasis, the current WHO tall cell criteria, met by 7.8% of PTCs, lacked statistical significance for DFS (p = 0.519). However, in the subset of tumours otherwise similar to the American Thyroid Association (ATA) guidelines low-risk category, WHO TC-PTC demonstrated a highly significant reduction in DFS (p = 0.004). In contrast, in intermediate to high-risk tumours, TC-PTC by WHO criteria lacked statistical significance (p = 0.384). We conclude that it may be simplistic to think of tall cell features as being present or absent, as both the height of the cells (two times versus three times) and the percentage of cells that are tall have different clinical significances in different contexts. Most importantly, the primary clinical significance of TC-PTC is restricted to PTCs that are otherwise low risk by ATA guidelines.

Clinical use of Molecular Data in Thyroid Nodules and Cancer

Over the past 3 decades, advances in the molecular genetics of thyroid cancer (TC) have been translated into diagnostic tests, prognostic markers, and therapeutic agents. The main drivers in differentiated TC pathogenesis are single-point mutations and gene fusions in components of the Mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase-protein kinase B/Akt (PI3K/Akt) pathways. Other important genetic alterations in the more advanced types of TC include TERT promoter, TP53, EIF1AX, and epigenetic alterations. Using this knowledge, several molecular tests have been developed for cytologically indeterminate thyroid nodules. Currently, 3 commercially available tests are in use including a DNA/RNA-based test (ThyroSeq v.3), an RNA-based test (Afirma Gene Sequencing Classifier), and a hybrid DNA/miRNA test, ThyGeNEXT/ThyraMIR. These tests are mostly used to rule out malignancy in Bethesda III and IV thyroid nodules because they all have high sensitivities and negative predictive values. Their common use, predominantly in the United States, has resulted in a significant reduction in unnecessary thyroid surgeries for benign nodules. Some of these tests also provide information on the underlying molecular drivers of TC; this may support decision making in initial TC management planning, although this practice has not yet been widely adopted. More importantly, molecular testing is essential in patients with advanced disease before using specific mono-kinase inhibitors (eg, selpercatinib for RET-altered TC) because these drugs are ineffective in the absence of a specific molecular target. This mini-review discusses the utilization of molecular data in the clinical management of patients with thyroid nodules and TC in these different clinical situations.

Molecular signature incorporating the immune microenvironment enhances thyroid cancer outcome prediction

Genomic and transcriptomic analysis has furthered our understanding of many tumors. Yet, thyroid cancer management is largely guided by staging and histology, with few molecular prognostic and treatment biomarkers. Here, we utilize a large cohort of 251 patients with 312 samples from two tertiary medical centers and perform DNA/RNA sequencing, spatial transcriptomics, and multiplex immunofluorescence to identify biomarkers of aggressive thyroid malignancy. We identify high-risk mutations and discover a unique molecular signature of aggressive disease, the Molecular Aggression and Prediction (MAP) score, which provides improved prognostication over high-risk mutations alone. The MAP score is enriched for genes involved in epithelial de-differentiation, cellular division, and the tumor microenvironment. The MAP score also identifies aggressive tumors with lymphocyte-rich stroma that may benefit from immunotherapy. Future clinical profiling of the stromal microenvironment of thyroid cancer could improve prognostication, inform immunotherapy, and support development of novel therapeutics for thyroid cancer and other stroma-rich tumors.

Genomic and Transcriptomic Characteristics of Metastatic Thyroid Cancers with Exceptional Responses to Radioactive Iodine Therapy

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.

Papillary Thyroid Carcinomas with Tall Cell Features: An Intermediate Entity between Classic and Tall Cell Subtypes

BACKGROUND While the diagnosis of papillary thyroid carcinomas with tall cell features (PTCtcf) is often made for carcinomas with histologic features intermediate between classic and tall cell subtypes of PTC (tcPTC), its comparative signature to that of either tcPTC or classic PTC is less clear. The objective of this study was to perform an integrative clinicopathologic and genomic analysis elucidating the spectrum of tcPTC, PTCtcf and classic PTC. METHODS We analyzed all consecutive patients with tcPTC and PTCtcf evaluated at a tertiary academic referral center between 2005-2020, as well as a comparative cohort of classic PTC, in a retrospective observational cohort analysis. Clinicopathological data were compared among the three groups, including progression-free survival (PFS), recurrent/persistent disease, and a negative composite outcome of death, progression, or need for advanced therapy. To specifically understand differences between tcPTC and PTCtcf, targeted next-generation sequencing (NGS) was performed in a subset of these cohorts. RESULTS A total of 292 patients were analyzed (81 tcPTC, 65 PTCtcf, 146 classic PTC). Thirteen percent tcPTC vs. 8% PTCtcf vs. 1% classic PTC had advanced AJCC stage (p=0.002). Similarly, macroscopic extrathyroidal extension was observed in 38% of tcPTC, 14% of PTCtcf and 12% of classic PTC (p<0.001). The 5-year PFS was 76.5%, 81.5% and 88.3% for tcPTC, PTCtcf and classic PTC, respectively, while the rates of the negative composite outcome 40.2% for tcPTC, 20.7% for PTCtcf and 11.2% for classic PTC (p<0.001). In a multivariable Cox regression analysis, the negative composite outcome was independently associated with tcPTC [HR 4.3 95% CI (1.1-16.1), p=0.03]. tcPTC demonstrated substantially more hotspot TERT promoter mutations than PTCtcf (44% vs. 6%, p=0.012). CONCLUSIONS Our study demonstrates a continuum of disease-specific risk of PTC, pointing at PTCtcf as an intermediate entity between tcPTC and classic PTC. These data provide a more refined understanding of risk at time of presentation, while better elucidating the diversity of genomic drivers.

Variants in TPO rs2048722, PTCSC2 rs925489 and SEMA4G rs4919510 affect thyroid carcinoma susceptibility risk

BACKGROUND

Thyroid carcinoma (THCA) is a malignant endocrine tumor all around the world, which is influenced by genetic and environmental factors.

OBJECTIVE

To explore the association between TPO rs2048722, PTCSC2 rs925489, SEMA4G rs4919510 polymorphisms and THCA susceptibility in Chinese population.

METHODS

We recruited 365 THCA patients and 498 normal controls for the study. Logistic regression analysis was used to evaluate the association between TPO rs2048722, PTCSC2 rs925489, SEMA4G rs4919510 polymorphisms and THCA susceptibility. MDR was used to assess the genetic interactions among the three SNPs.

RESULTS

Overall analysis demonstrated that rs925489 of PTCSC2 was evidently associated with increased risk of THCA in multiple genetic models (OR = 1.59, 95%CI = 1.12-2.24, p = 0.009). The results of stratified analysis illustrated that rs2048722 of TPO can significantly increase the THCA susceptibility of participants less than or equal to 44 years old and smokers. Similarly, rs925489 of PTCSC2 obviously improved the risk of THCA among participants older than 44 years, males, smokers and drinkers. However, rs4919510 of SEMA4G has a protective effect on the development of THCA among participants with less than or equal to 44 years old and non-drinkers. Interestingly, there was a strong genetic interaction among the three SNPs in the occurrence of THCA risk.

CONCLUSION

TPO rs2048722, PTCSC2 rs925489 and SEMA4G rs4919510 polymorphisms were evidently associated with the risk of THCA in the Chinese population, which was affected by age, gender, smoking and drinking consumption.

Disease-Specific Survival Trends for Patients Presenting with Differentiated Thyroid Cancer and Distant Metastases in the United States, 1992-2018

Objective: Differentiated thyroid cancer (DTC) is associated with an excellent prognosis, but patients with distant metastatic DTC have a 10-year disease-specific survival (DSS) of just 50%. The incidence of distant metastatic DTC has steadily increased in the United States since the 1980s. The aim of this study was to examine trends in survival and treatment for patients with distant metastatic DTC. Methods: In this population-based, retrospective cohort study, patients with distant metastatic DTC were identified from the Surveillance, Epidemiology, and End Results-13 cancer registry program. Multivariable logistic and Cox regression analyses were used to examine factors associated with DSS and management. Annual percentage changes in treatment patterns were calculated using log-linear regression. Results: During 1992-2018, 1991 patients (69.7% white, 58.0% female, 47.5% aged ≥65 years) were diagnosed with distant metastatic DTC. Papillary thyroid cancer was the most common histological type (74.5%). While the 10-year DSS for overall DTC increased over time (95.4% for patients diagnosed in 1992-1998, 96.6% in 1999-2008, and 97.3% in 2009-2018; p < 0.01), 10-year DSS for DTC with distant metastases did not change (50.2%, 47.3%, and 52.4%, respectively; p = 0.48). Ten-year DSS rates were reduced for patients aged ≥65 years (28.1%), patients undergoing nonsurgical treatment with external beam radiation therapy and/or systemic therapy (6.0%), and patients undergoing no/unknown treatment (32.8%). On multivariable analysis, oncocytic carcinoma, age 65-79 and ≥80 years, male sex, node-positive disease, larger tumor size, nonsurgical treatment, and no/unknown treatment were associated with increased risk of thyroid cancer death. Between 1992 and 2018, the rate of nonsurgical treatment increased, on average, 1.3% per year (1992-1998: 22.9% vs. 2009-2018: 25.6%; p = 0.03), and the rate of patients receiving no/unknown treatment increased 1.9% per year (1992-1998: 11.3% vs. 2009-2018: 15.6%; p = 0.01). Patients aged 65-79 and ≥80 years were more likely than younger patients to receive nonsurgical management or no/unknown treatment. Conclusion: Patients diagnosed with distant metastatic DTC have experienced no improvement in DSS over the past three decades. An increasing proportion of patients diagnosed with distant metastatic DTC are receiving nonsurgical treatment or no/unknown treatment over time; the proportion was highest among the oldest patients.

Advances in Thyroid Carcinoma

"Thyroid cancer" encompasses a heterogeneous group of tumors that range from the predominant papillary thyroid cancer (PTC) subtype, which shows excellent survival rates, to the poorly differentiated (PDTC) and anaplastic thyroid cancer (ATC) forms, accounting for most of the disease-related morbidity and mortality [...].

LncRNA ABHD11-AS1 promotes tumor progression in papillary thyroid carcinoma by regulating EPS15L1/EGFR signaling pathway

OBJECTIVES

lncRNA ABHD11 antisense RNA 1 (ABHD11-AS1) acts as an oncogene involved in papillary thyroid carcinoma (PTC) occurrence and progression. ABHD11-AS1 exerts biologic functions by some miRNAs and proteins to regulate multiple targets. Identification of novel mechanism of ABHD11-AS1 could be helpful in therapeutic targeting for PTC treatment.

METHODS

Differentially expressed lncRNAs were selected from TCGA database. qRT-PCR analysis was applied to examine the expression of ABHD11-AS1 in PTC cell lines and tissues. The relationship of ABHD11-AS1 expression and clinicopathological features was analyzed by Kaplan-Meier analysis. Two PTC cell lines (TPC-1 and KTC-1) were transfected with pcDNA 3.1, pcDNA3.1-ABHD11-AS1, si-NC and si-ABHD11-AS1, respectively, to verify the ABHD11-AS1 oncogene-regulating capacity to promote tumor progression. The cell metastasis and proliferation had been evaluated both in vitro and in vivo.

RESULTS

High expression of ABHD11-AS1 was found in PTC tissues (P < 0.01), which was significantly correlated with lymph node metastasis (P < 0.05). ABHD11-AS1 overexpression noticeably promoted cell proliferation, migration, and invasion capabilities, which were obviously decreased upon ABHD11-AS1 knockdown. ABHD11-AS1 positively regulated EGFR/EPS15L1 pathway, as EGFR, EPS15L1, STAT3, and p-STAT3 were activated.

CONCLUSION

ABHD11-AS1 promotes tumor progression in PTC by regulating EPS15L1/EGFR pathway.

Positive Correlation of Thyroid Nodule Cytology with Molecular Profiling-a Single-Center Experience

Despite several reports on the association between molecular profiling, aggressive histology, and clinical outcomes, the association between mutation expression and pre-operative cytology is yet to be demonstrated. Therefore, we performed a retrospective, single-center study, including all patients who underwent molecular profiling of thyroid nodules in Bethesda System for Reporting Thyroid Cytopathology (BSRTC) categories III to VI, between 2018 and 2019. Medical records were reviewed to collect demographics, cytology results according to BSRTC, final pathology (presence of malignancy and its type, as well as presence of aggressive features, including extrathyroidal extension, positive neck lymph nodes, and multifocality), and the identified genetic variants stratified by risk levels, according to the 2015 ATA guidelines. We supplemented this analysis with a systematic review to identify the variant distributions across the literature. We included data on 55 nodules from 48 patients for the final analysis. A significant positive correlation was found between BSRTC categories and the mutation risk level, shown by an increase in the intermediate to high-risk mutation rate in the higher BSRTC categories (Rs = 0.660, p ≤ 0.001). A significant positive correlation was also found between mutation risk levels and the presence of malignancy and aggressive tumor features (Rs = 0.637, p < 0.001 and Rs = 0.459, p = 0.006, respectively). This novel positive and significant correlation between BSRTC categories and the mutation risk level provides additional insight to aid clinicians in the interpretation of BSRTC results and may contribute to the discussion of appropriate management of thyroid nodule with patients.

Mutation in Genes Encoding Key Functional Groups Additively Increase Mortality in Patients with BRAFV600E-Mutant Advanced Papillary Thyroid Carcinoma

The prognosis of BRAFV600E-mutant papillary thyroid carcinoma (PTC) ranges from indolent to highly aggressive courses. To better define the genetic diversity of this subtype, we evaluated the survival according to the presence of an additional mutation in genes encoding functional groups (FGs) in BRAFV600E-mutant advanced PTC patients. Targeted next-generation sequencing was performed in primary tumors of 50 BRAFV600E-mutant PTCs with distant metastasis or aggressive variants. The mutation in genes encoding FGs included alterations in histone methyltransferases, SWI/SNF subunit, and the PI3K/AKT/mTOR pathway. The primary outcome was overall survival (OS). Fifteen patients only had the BRAFV600E-mutation (group 1), 22 had BRAFV600E and mutation other than FGs (group 2), and 13 had BRAFV600E and FG mutation (group 3). OS was significantly lower in patients with FG mutations (p = 0.001) than those without, and group 3 patients had the worst survival (p = 0.004). OS significantly varied among none, one, or two FG mutation sites (p = 0.005). Presence of FG mutation was independently associated with increased mortality (hazard ratio 11.65, 95% confidence interval 1.39-97.58, p = 0.024). Coexistence of mutations in BRAFV600E and genes encoding FGs was associated with high mortality. Identification of FG mutation in BRAFV600E-mutant PTCs may be valuable in risk stratifying this subtype.

Carbonic-anhydrase IX expression is increased in thyroid cancer tissue and represents a potential therapeutic target to eradicate thyroid tumor-initiating cells

The expression of Carbonic-anhydrase IX (CAIX) in thyroid cancer (TC) subtypes was determined and its role in cancer cell growth and tumor-initiating cells (TICs) investigated. Immunohistochemistry in 114 TC patients revealed that CAIX expression was increased in tumor specimens of papillary, follicular and anaplastic TCs compared to normal thyroid tissue. Clinicopathological data indicated that lymph node metastases were more frequent in patients with high CAIX expression. The Cancer Genome Atlas database analysis demonstrated that a strong CAIX-mRNA expression was associated with advanced tumor stages and poor survival in TCs. In TC cell lines, CAIX expression was elevated in tumorspheres compared to monolayer cultures and was associated with an increased expression of stemness markers. Genetic knockdown or pharmacological inhibition of CAIX suppressed cell proliferation and the TIC ability to form tumorspheres by an induction of apoptosis and cell-cycle arrest. These findings suggest CAIX as a potential prognostic marker and a therapeutic target for thyroid cancer.