Combination Targeted Therapy with Pembrolizumab and Lenvatinib in Progressive, Radioiodine-Refractory Differentiated Thyroid Cancers

PURPOSE

Lenvatinib, a potent multikinase inhibitor, improves progression-free survival (PFS) in patients with radioiodine (RAI)-refractory differentiated thyroid cancer; however, most patients experience disease progression, warranting further therapy. We evaluated the efficacy and safety of lenvatinib plus pembrolizumab in these patients.

PATIENTS AND METHODS

We enrolled patients with progressive, RAI-refractory differentiated thyroid cancer who were either naïve to multikinase inhibitors (cohort 1) or who had progressed on lenvatinib (cohort 2). Patients received oral lenvatinib daily (cohort 1, 20 mg; cohort 2, dose at progression) and intravenous pembrolizumab (200 mg) every 21 days.

RESULTS

In cohorts 1 and 2, 30 and 27 patients were enrolled, respectively. Adverse events were consistent with those observed in other cancers. In cohort 1, the confirmed overall response rate was 65.5%. There were no complete responses (primary endpoint). The 12- and 18-month PFS were 72.0% and 58.0%, respectively, and the median PFS was 26.8 months. In cohort 2, the confirmed overall response rate was 16% (primary endpoint), and the median PFS was 10.0 months (95% confidence interval, 7.0-17.9 months). Tumor histology, driver mutations, and immune-related biomarkers, including PD-L1 expression, thyroid-specific antibody levels, and CD8+ T-cell tumor infiltrate, did not correlate with response to therapy. Increased baseline peripheral blood monocytes and neutrophil to lymphocyte ratio were associated with a worse PFS in cohort 1.

CONCLUSIONS

Lenvatinib plus pembrolizumab may enhance the durability of lenvatinib monotherapy in lenvatinib-naïve patients. Furthermore, the addition of pembrolizumab may be a viable salvage therapy for patients who have progressed on lenvatinib.

Molecular Alterations and Comprehensive Clinical Management of Oncocytic Thyroid Carcinoma: A Review and Multidisciplinary 2023 Update

Importance

Oncocytic (Hürthle cell) thyroid carcinoma is a follicular cell-derived neoplasm that accounts for approximately 5% of all thyroid cancers. Until recently, it was categorized as a follicular thyroid carcinoma, and its management was standardized with that of other differentiated thyroid carcinomas. In 2022, given an improved understanding of the unique molecular profile and clinical behavior of oncocytic thyroid carcinoma, the World Health Organization reclassified oncocytic thyroid carcinoma as distinct from follicular thyroid carcinoma. The International Thyroid Oncology Group and the American Head and Neck Society then collaborated to review the existing evidence on oncocytic thyroid carcinoma, from diagnosis through clinical management and follow-up surveillance.

Observations

Given that oncocytic thyroid carcinoma was previously classified as a subtype of follicular thyroid carcinoma, it was clinically studied in that context. However, due to its low prevalence and previous classification schema, there are few studies that have specifically evaluated oncocytic thyroid carcinoma. Recent data indicate that oncocytic thyroid carcinoma is a distinct class of malignant thyroid tumor with a group of distinct genetic alterations and clinicopathologic features. Oncocytic thyroid carcinoma displays higher rates of somatic gene variants and genomic chromosomal loss of heterozygosity than do other thyroid cancers, and it harbors unique mitochondrial DNA variations. Clinically, oncocytic thyroid carcinoma is more likely to have locoregional (lymph node) metastases than is follicular thyroid carcinoma-with which it was formerly classified-and it develops distant metastases more frequently than papillary thyroid carcinoma. In addition, oncocytic thyroid carcinoma rarely absorbs radioiodine.

Conclusions and Relevance

The findings of this review suggest that the distinct clinical presentation of oncocytic thyroid carcinoma, including its metastatic behavior and its reduced avidity to radioiodine therapy, warrants a tailored disease management approach. The reclassification of oncocytic thyroid carcinoma by the World Health Organization is an important milestone toward developing a specific and comprehensive clinical management for oncocytic thyroid carcinoma that considers its distinct characteristics.

Thyroid Cancer Polygenic Risk Score Improves Classification of Thyroid Nodules as Benign or Malignant

CONTEXT

Thyroid nodule ultrasound-based risk stratification schemas rely on the presence of high-risk sonographic features. However, some malignant thyroid nodules have benign appearance on thyroid ultrasound. New methods for thyroid nodule risk assessment are needed.

OBJECTIVE

We investigated polygenic risk score (PRS) accounting for inherited thyroid cancer risk combined with ultrasound-based analysis for improved thyroid nodule risk assessment.

METHODS

The convolutional neural network classifier was trained on thyroid ultrasound still images and cine clips from 621 thyroid nodules. Phenome-wide association study (PheWAS) and PRS PheWAS were used to optimize PRS for distinguishing benign and malignant nodules. PRS was evaluated in 73 346 participants in the Colorado Center for Personalized Medicine Biobank.

RESULTS

When the deep learning model output was combined with thyroid cancer PRS and genetic ancestry estimates, the area under the receiver operating characteristic curve (AUROC) of the benign vs malignant thyroid nodule classifier increased from 0.83 to 0.89 (DeLong, P value = .007). The combined deep learning and genetic classifier achieved a clinically relevant sensitivity of 0.95, 95% CI [0.88-0.99], specificity of 0.63 [0.55-0.70], and positive and negative predictive values of 0.47 [0.41-0.58] and 0.97 [0.92-0.99], respectively. AUROC improvement was consistent in European ancestry-stratified analysis (0.83 and 0.87 for deep learning and deep learning combined with PRS classifiers, respectively). Elevated PRS was associated with a greater risk of thyroid cancer structural disease recurrence (ordinal logistic regression, P value = .002).

CONCLUSION

Augmenting ultrasound-based risk assessment with PRS improves diagnostic accuracy.

Anthropometric, dietary, and lifestyle factors and risk of advanced thyroid cancer: The NIH-AARP diet and health cohort study

BACKGROUND

Most patients diagnosed with thyroid cancer have low-risk disease, but some have a higher risk for persistent or recurrent disease and even death from thyroid cancer. Few studies have evaluated potential anthropometric, lifestyle, or dietary risk factors for advanced or aggressive types of thyroid cancer.

METHODS

Using data from a large US cohort study, we examined associations for high-risk thyroid cancer (HRTC) and, separately, low-risk thyroid cancer (LRTC) in relation to anthropometric factors, diet, smoking, and alcohol consumption. The National Institutes of Health-American Association of Retired Persons (NIH-AARP) Diet and Health Study included 304,122 participants (124,656 women and 179,466 men) without a history of cancer who completed a mailed questionnaire in 1996-1997 and were followed for cancer incidence through 2011 via linkages with state cancer registries. Hazard ratios (HRs) for anthropometric, dietary, and lifestyle factors in relation to HRTC or LRTC, defined using guidance from the American Thyroid Association initial risk of recurrence classification, were calculated using multivariable-adjusted Cox proportional hazards regression models.

RESULTS

During follow-up (median = 10.1 years), 426 participants were diagnosed with HRTC (n = 95) or LRTC (n = 331). In models combining men and women, baseline waist circumference (per 5 cm, HR = 1.13, 95% confidence interval [CI] 1.01-1.27) and weight gain from age 18 years to baseline age (per 5 kg, HR = 1.14, 95% CI 1.02-1.28) were positively associated with risk of HRTC but not LRTC. In contrast, vegetable intake (per cup equivalents/day, HR = 1.15, 95% CI 1.01-1.30), cigarette smoking (current vs. never, HR = 0.39, 95% CI 0.23-0.68), and alcohol consumption (per drink/day, HR = 0.83, 95% CI 0.70-0.97) were associated with risk of LRTC but not HRTC. The association of LRTC risk with vegetable intake was limited to men, and that of current smoking was more pronounced in women.

CONCLUSIONS

Our findings suggest that greater waist circumference and adulthood weight gain are associated with thyroid cancers at higher risk for recurrence. These results may have implications for the primary prevention of advanced thyroid cancer.

Molecular Profiling of 50 734 Bethesda III-VI Thyroid Nodules by ThyroSeq v3: Implications for Personalized Management

CONTEXT

Comprehensive genomic analysis of thyroid nodules for multiple classes of molecular alterations detected in a large series of fine needle aspiration (FNA) samples has not been reported.

OBJECTIVE

To determine the prevalence of clinically relevant molecular alterations in Bethesda categories III-VI (BCIII-VI) thyroid nodules.

METHODS

This retrospective analysis of FNA samples, tested by ThyroSeq v3 using Genomic Classifier and Cancer Risk Classifier at UPMC Molecular and Genomic Pathology laboratory, analyzed the prevalence of diagnostic, prognostic, and targetable genetic alterations in a total of 50 734 BCIII-VI nodules from 48 225 patients.

RESULTS

Among 50 734 informative FNA samples, 65.3% were test-negative, 33.9% positive, 0.2% positive for medullary carcinoma, and 0.6% positive for parathyroid. The benign call rate in BCIII-IV nodules was 68%. Among test-positive samples, 73.3% had mutations, 11.3% gene fusions, and 10.8% isolated copy number alterations. Comparing BCIII-IV nodules with BCV-VI nodules revealed a shift from predominantly RAS-like alterations to BRAF V600E-like alterations and fusions involving receptor tyrosine kinases (RTK). Using ThyroSeq Cancer Risk Classifier, a high-risk profile, which typically included TERT or TP53 mutations, was found in 6% of samples, more frequently BCV-VI. RNA-Seq confirmed ThyroSeq detection of novel RTK fusions in 98.9% of cases.

CONCLUSION

In this series, 68% of BCIII-IV nodules were classified as negative by ThyroSeq, potentially preventing diagnostic surgery in this subset of patients. Specific genetic alterations were detected in most BCV-VI nodules, with a higher prevalence of BRAF and TERT mutations and targetable gene fusions compared to BCIII-IV nodules, offering prognostic and therapeutic information for patient management.

Thyroid hormone enhances estrogen-mediated proliferation and cell cycle regulatory pathways in steroid receptor-positive breast Cancer

Estrogen receptor (ER) α expression and associated signaling is a major driver of over two-thirds of all breast cancers (BC). ER targeting strategies are typically used as a first-line therapy in patients with steroid receptor positive (SR+) disease. Secondary resistance to anti-estrogenic agents may occur with clonal expansion and disease progression. Mechanisms underlying hormone resistance are an expanding field of significant translational importance. Cross-talk with other nuclear hormones, receptors, and signaling pathways, including thyroid hormones (TH) and their receptors (THRs), have been shown to promote endocrine therapy resistance in some studies. We have shown that TH replacement therapy (THRT) was independently and significantly associated with higher rates of relapse and mortality in SR positive (+), node-negative (LN-) BC patients, whereas it showed no association with outcomes in SR negative (-) patients. LN-, SR+ patients receiving THRT and tamoxifen had the worst outcomes, suggesting a pro-carcinogenic interaction that significantly and independently shortened survival and increased mortality. Using in vivo and in vitro models, we previously showed hormonal cross-talk, altered gene signaling, target gene activation, and resistance to tamoxifen in the presence of TH. In this report, we show TH ± E2 ± tamoxifen inhibits cell cycle control signaling, reduces apoptosis, and enhances cell proliferation, tumor growth, tamoxifen resistance, and clonal expansion. Mechanistically these changes involve numerous genes and pathways, including critical cell cycle regulatory proteins and genes identified using various molecular methods. These studies facilitate a greater mechanistic understanding of the biological and molecular impact of TH on SR+ BC.

Computer-Assisted Levothyroxine Dose Selection for the Treatment of Postoperative Hypothyroidism

Background: Thyroid hormone replacement with levothyroxine (LT4) is a recommended treatment for patients undergoing thyroidectomy. The starting LT4 dose is frequently calculated based on the patient's weight. However, the weight-based LT4 dosing performs poorly in clinical practice, with only ∼30% of patients achieving target thyrotropin (TSH) levels at the first thyroid function testing after treatment initiation. A better way to calculate the LT4 dose for patients with postoperative hypothyroidism is needed. Methods: In this retrospective cohort study we used demographic, clinical, and laboratory data for 951 patients after thyroidectomy and several regression and classification machine learning methods to develop an LT4 dose calculator for treating postoperative hypothyroidism targeting the desired TSH level. We compared the accuracy with the current standard-of-care practice and other published algorithms and evaluated generalizability with fivefold cross-validation and out-of-sample testing. Results: The retrospective clinical chart review showed that only 285/951 (30%) patients met their postoperative TSH goal. Obese patients were overtreated with LT4. An ordinary least squares regression based on weight, height, age, sex, calcium supplementation, and height:sex interaction predicted prescribed LT4 dose in 43.5% of all patients and 45.3% of patients with normal postoperative TSH (0.45-4.5 mIU/L). The ordinal logistic regression, artificial neural networks regression/classification, and random forest methods achieved comparable performance. LT4 calculator recommended lower LT4 doses to obese patients. Conclusions: The standard-of-care LT4 dosing does not achieve the target TSH in most thyroidectomy patients. Computer-assisted LT4 dose calculation performs better by considering multiple relevant patient characteristics and providing personalized and equitable care to patients with postoperative hypothyroidism. Prospective validation of LT4 calculator performance in patients with various TSH goals is needed.

Preclinical Models of Follicular Cell-Derived Thyroid Cancer: An Overview from Cancer Cell Lines to Mouse Models

The overall prognosis of thyroid cancer is excellent, but some patients have grossly invasive disease and distant metastases with limited responses to systemic therapies. Thus, relevant preclinical models are needed to investigate thyroid cancer biology and novel treatments. Different preclinical models have recently emerged with advances in thyroid cancer genetics, mouse modeling and new cell lines. Choosing the appropriate model according to the research question is crucial to studying thyroid cancer. This review will discuss the current preclinical models frequently used in thyroid cancer research, from cell lines to mouse models, and future perspectives on patient-derived and humanized preclinical models in this field.

RF11 | PSAT234 Deep learning analysis of thyroid nodule ultrasound images has high sensitivity and negative predictive value to rule-out thyroid cancer

Purpose

To evaluate deep learning analysis of thyroid nodule ultrasound images as a rule-out test for thyroid malignancy.

Methods

Supervised deep learning (DL) classifier of thyroid nodules was trained on 32,545 thyroid US images from 621 nodules representing all major benign and malignant types of thyroid lesions and tested on an independent set of 145 nodules collected at a different healthcare system in the United States. The Big Transfer BiT-M ResNet-50×1 convolutional neural net architecture was modified to contain 3, 4, 6 and 3 PreActBottleneck units per block 1 through 4. Weights pretrained on the ImageNet-21k dataset were loaded and weights for blocks 3 and 4 were fine-tuned for the binary classification task of distinguishing benign and malignant thyroid nodules.

Results

The deep learning thyroid nodule classifier achieved an area under receiver operating characteristic curve (AUROC) of 0.889 on five-fold cross-validation. The AUROC improved when images were scaled by nodule size and six randomly selected cine clip frames were added to the training set per epoch. GradCAM class activation heatmaps revealed that microcalcifications and spongiform appearance were reliably recognized by the classifier as malignant and benign features, respectively. Spongiform nodules were found to be benign even when microcystic spaces constituted less than 50% of nodule volume.

To investigate the clinical relevance of the benign vs. malignant classifier, the binary classification threshold for the probability of malignancy generated by model was set at 7% to achieve sensitivity and negative predictive value (NPV) comparable to that of the fine needle aspiration biopsy (FNA). At this threshold, cross-validated deep-learning model achieved a sensitivity of 90%, specificity of 63%, positive predictive value (PPV) of 46% and negative predictive value of 94%. When tested on an independent image set that includes 18 classic papillary thyroid cancers (PTC), 5 follicular variant PTC, 4 medullary thyroid cancers, 3 follicular thyroid cancers (FTC), and 1 Hurthle cell thyroid cancer, the DL classifier achieved AUROC of 0.88, sensitivity of 97%, specificity of 61%, PPV of 40% and NPV of 99%. A single minimally-invasive FTC that had no suspicious features on thyroid ultrasound was incorrectly classified as benign.

Conclusions

This study demonstrates that the ultrasound-based deep-learning classifier of thyroid nodules achieves sensitivity and negative predictive value comparable to that of thyroid fine needle aspiration (FNA). Clinicians may use this tool to augment clinical judgment when determining whether to perform FNA procedures.

Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Saturday, June 11, 2022 1:06 p.m. - 1:11 p.m.

What's in a Name? A Cost-Effectiveness Analysis of the Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features' Nomenclature Revision

Background: The noninvasive subtype of encapsulated follicular variant of papillary thyroid carcinoma (eFVPTC) has been reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in 2016 to reflect the indolent behavior and favorable prognosis of this type of tumor. This terminology change has also de-escalated its management approach from cancer treatment to a more conservative treatment strategy befitting a benign thyroid neoplasm. Objective: To characterize the reduced health care costs and improved quality of life (QOL) from management of NIFTP as a nonmalignant tumor compared with the previous management as eFVPTC. Methods: A cost-effectiveness analysis was performed by creating Markov models to simulate two management strategies for NIFTP: (i) de-escalated management of the tumor as NIFTP involving lobectomy with reduced follow-up, (ii) management of the tumor as eFVPTC involving completion thyroidectomy/radioactive iodine ablation for some patients, and follow-up recommended for carcinoma. The model was simulated for 5 and 20 years following diagnosis of NIFTP. Aggregate costs and quality-life years were measured. One-way sensitivity analysis was performed for all variables. Results: Over a five-year simulation period, de-escalated management of NIFTP had a total cost of $12,380.99 per patient while the more aggressive management of the tumor as eFVPTC had a total cost of $16,264.03 per patient (saving $3883.05 over five years). Management of NIFTP provided 5.00 quality-adjusted life years, whereas management as eFVPTC provided 4.97 quality-adjusted life years. Sensitivity analyses showed that management of NIFTP always resulted in lower costs and greater quality-adjusted life years (QALYs) over the sensitivity ranges for individual variables. De-escalated management for NIFTP is expected to produce ∼$6-42 million in cost savings over a five-year period for these patients, and incremental 54-370 QALYs of increased utility in the United States. Conclusion: The degree of cost savings and improved patient utility of de-escalated NIFTP management compared with traditional management was estimated to be $3883.05 and 0.03 QALYs per patient. We demonstrate that these findings persisted in sensitivity analysis to account for variability in recurrence rate, surveillance approaches, and other model inputs. These findings allow for greater understanding of the economic and QOL impact of the NIFTP reclassification.

Lenvatinib Plus Anti-PD-1 Combination Therapy for Advanced Cancers: Defining Mechanisms of Resistance in an Inducible Transgenic Model of Thyroid Cancer

Background: Combination therapy with lenvatinib plus programmed death-1 (PD-1) immune checkpoint blockades (ICBs) is under investigation in many solid tumors, including thyroid cancer. Lenvatinib is known to reduce angiogenesis and may overturn the immunosuppressive effects of vascular endothelial growth factor in the tumor microenvironment. Previous studies investigating the effects of VEGF receptor inhibition on the immune response were performed in rapidly growing tumor models where immune equilibrium is not established before treatment. We hypothesize that physiologically relevant preclinical models are necessary to define mechanisms of resistance to immune-targeted combination therapies. Methods: We utilized the TPO-CreER/Braf^V600E/wt/Trp53^{Δex2-10/Δex2-10} inducible transgenic model of advanced thyroid cancer to investigate lenvatinib treatment in the context of an anti-PD-1 ICB. Following tumor establishment, 3.5 months postinduction, mice were treated with high- (10 mg/kg) or low-dose (2 mg/kg) lenvatinib, anti-PD-1, or combination of lenvatinib with anti-PD-1. Tumor volume and lung metastases were assessed in each group. Immune infiltrate was characterized by flow cytometry and immunohistochemistry, and TCRß sequencing was performed to further investigate the T cell response. Results: Both low- and high-dose lenvatinib reduced tumor volume, while anti-PD-1 had no effect, alone or in combination. Although both low- and high-dose lenvatinib reduced vascular density, low-dose lenvatinib was superior in controlling tumor size. Lung metastases and survival were not improved with therapy despite the effects of lenvatinib on primary tumor size. Low-dose lenvatinib treatment led to a subtle reduction in the dominant Ly6G⁺CD11b⁺ myeloid cell population and was associated with increased CD4⁺ T cell infiltrate and enrichment in 4-1BB⁺ and granzyme B⁺ CD4⁺ T cells and FoxP3⁺ regulatory T cells. Polyclonal T cell expansion was evident in the majority of mice, suggesting that a tumor-specific T cell response was generated. Conclusions: The effects of lenvatinib on the immune response were most pronounced in mice treated with low-dose lenvatinib, suggesting that dose should be considered in clinical application. While the immune-modulating potential of lenvatinib is encouraging, alterations in the immune milieu and T cell activation status were insufficient to sustain durable tumor regression, even with added anti-PD-1. Additional studies are necessary to develop more effective combination approaches in low-mutation burden tumors, such as thyroid cancer.

Do Ultrasound Patterns and Clinical Parameters Inform the Probability of Thyroid Cancer Predicted by Molecular Testing in Nodules with Indeterminate Cytology?

Background: Molecular testing (MT) is commonly used to refine cancer probability in thyroid nodules with indeterminate cytology. Whether or not ultrasound (US) patterns and clinical parameters can further inform the risk of thyroid cancer in nodules predicted to be positive or negative by MT remains unknown. The aim of this study was to test if clinical parameters, including patient age, sex, nodule size (by US), Bethesda category (III, IV, V), US pattern (American Thyroid Association [ATA] vs. American College of Radiology Thyroid Image Reporting and Data System [TI-RADS] systems), radiation exposure, or family history of thyroid cancer can modify the probability of thyroid cancer or noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) predicted by MT. Methods: We studied 257 thyroid nodules in 232 patients from 10 study centers with indeterminate fine needle aspiration cytology and informative MT results using the ThyroSeq v3 genomic classifier (TSv3). Univariate and multivariate logistic regression was used for data analysis. Results: The presence of cancer/NIFTP was associated with positive TSv3 results (odds ratio 61.39, p < 0.0001). On univariate regression, patient sex, age, and Bethesda category were associated with cancer/NIFTP probability (p < 0.05 for each). Although ATA (p = 0.1211) and TI-RADS (p = 0.1359) US categories demonstrated positive trends, neither was significantly associated with cancer/NIFTP probability. A multivariate regression model incorporating the four most informative non-MT covariates (sex, age, Bethesda category, and ATA US pattern; Model No. 1) yielded a C index of 0.653; R² = 0.108. When TSv3 was added to Model number 1, the C index increased to 0.888; R² = 0.572. However, age (p = 0.341), Bethesda category (p = 0.272), and ATA US pattern (p = 0.264) were nonsignificant, and other than TSv3 (p < 0.0001), male sex was the only non-MT parameter that potentially contributed to cancer/NIFTP risk (p = 0.095). The simplest and most efficient clinical model (No. 3) incorporated TSv3 and sex (C index = 0.889; R² = 0.588). Conclusions: In this multicenter study of thyroid nodules with indeterminate cytology and MT, neither the ATA nor TI-RADS US scoring systems further informed the risk of cancer/NIFTP beyond that predicted by TSv3. Although age and Bethesda category were associated with cancer/NIFTP probability on univariate analysis, in sequential nomograms they provided limited incremental value above the high predictive ability of TSv3. Patient sex may contribute to cancer/NIFTP risk in thyroid nodules with indeterminate cytology.

Tailoring the approach to radioactive iodine treatment in thyroid cancer

The treatment of differentiated thyroid cancer continues to move away from a 'one size fits all' approach to a process of tailored therapeutic decision-making that incorporates disease-specific factors and individual patient preferences. Management options range from active surveillance to thyroid lobectomy to total thyroidectomy with or without the use of postoperative radioactive iodine (RAI). RAI may be administered for one or more reasons: Thyroid remnant ablation, adjuvant therapy, or therapy for persistent structural disease. It is important to be cognizant of the therapeutic intent of RAI and weigh the risks and benefits of treatment for each individual patient. Risk stratification should be used to identify those patients who are most likely to benefit from RAI and guide therapeutic choices. Available data suggest that RAI can be safely deferred for most patients considered at low risk for structural recurrence, while adjuvant RAI is associated with improved disease-free survival in patients with higher-risk disease. Although progress has been made, many areas of uncertainty related to the use of RAI remain. These include: (1) The appropriate selection of intermediate-risk patients to receive adjuvant RAI, (2) the superiority or inferiority of different RAI dosing activities, (3) the optimal approach to the use of RAI in special populations, including patients with end-stage renal disease and children, and (4) the management of patients with RAI-refractory disease.

Exogenous Thyroid Hormone Is Associated with Shortened Survival and Upregulation of High-Risk Gene Expression Profiles in Steroid Receptor-Positive Breast Cancers

PURPOSE

Thyroid disease is a frequent comorbidity in women with breast cancer, and many require thyroid hormone replacement therapy (THRT). We postulated that THRT has a deleterious clinical effect mechanistically through hormonal interactions, nuclear receptor cross-talk, and upregulation of high-risk breast cancer genes.

EXPERIMENTAL DESIGN

Observational studies of patients with lymph node-negative (LN-) breast cancer (n = 820 and n = 160) were performed to test interactions between THRT and clinical, histologic, outcome, and treatment variables. Differences between the two cohorts include but are not limited to patient numbers, decades of treatment, duration of follow-up/treatment, tumor sizes, incidence, and type and dose/regimen of antihormonal and/or chemotherapeutic agents. In vivo and vitro models, in silico databases, and molecular methods were used to study interactions and define mechanisms underlying THRT effects.

RESULTS

THRT significantly and independently reduced disease-free and breast cancer-specific overall survival of only the steroid receptor (SR)-positive (as compared with SR-negative) node-negative patients in both long-term observational studies. Patients with SR+ LN- breast cancer who received THRT and tamoxifen experienced the shortest survival of all treatment groups. A less potent interaction between THRT and aromatase inhibitors was noted in the second patient cohort. Using in vivo and in vitro models, TH administration enhanced estrogen and TH-associated gene expression and proliferation, nuclear colocalization of estrogen receptor and thyroid hormone receptor, and activation of genes used clinically to predict tumor aggression in SR+ breast cancer, including the IGF-IR, WNT, and TGFβ pathways.

CONCLUSIONS

We show clinically significant adverse interactions between THRT, estrogenic, and oncogenic signaling in patients with SR+ LN- breast cancer.

Comprehensive Immune Profiling of Medullary Thyroid Cancer

Background: Despite advances in targeted kinase inhibitor development for patients with medullary thyroid cancer (MTC), most patients develop resistance and would benefit from alternative approaches. Immune-based therapies are now considered for patients with progressive MTC. This study is the first comprehensive assessment of the immune milieu, immune-suppressive molecules, and potential tumor antigens in patients with MTC. Methods: Primary and/or regionally metastatic tumor tissues from 46 patients with MTC were screened for immune infiltrates by using standard immunohistochemistry (IHC) and further analyzed by multispectral imaging for T cell and myeloid markers. RNASeq expression profiling was performed in parallel. RNASeq, targeted sequencing, and IHC techniques identified cancer-associated mutations and MTC-enriched proteins. Results: Organized immune infiltration was observed in 49% and 90% of primary and metastatic tumors, respectively. CD8⁺ cells were the dominant T cell subtype in most samples, while CD163⁺ macrophages were most frequent among myeloid infiltrates. PD-1⁺ T cells were evident in 24% of patients. Myeloid subsets were largely major histocompatibility complex II (MHCII^-), suggesting a dysfunctional phenotype. Expression profiling confirmed enrichment in T cell, macrophage, and inflammatory profiles in a subset of samples. PD-L1 was expressed at low levels in a small subset of patients, while the immune regulatory molecules CD155 and CD47 were broadly expressed. Calcitonin, GRP, HIST1H4E, NOMO3, and NPIPA2 were highly and specifically expressed in MTC. Mutations in tumor suppressors, PTEN and p53, and mismatch repair genes, MSH2 and MSH6, may be relevant to disease progression and antigenicity. Conclusions: This study suggests that MTC is a more immunologically active tumor that has been previously reported. Patients with advanced MTC should be screened for targetable antigens and immune checkpoints to determine their eligibility for current clinical trials. Additional studies are necessary to fully characterize the antigenic potential of MTC and may encourage the development of adoptive T cells therapies for this rare tumor.

A Survey of American Thyroid Association Members Regarding the 2015 Adult Thyroid Nodule and Differentiated Thyroid Cancer Clinical Practice Guidelines

Background: The 2015 American Thyroid Association (ATA) clinical practice guidelines (CPGs) on management of thyroid nodules (TNs) and differentiated thyroid cancer (DTC) in adults were developed to inform clinicians, patients, researchers, and health policy makers about the best available evidence, and its limitations, relating to management of these conditions. Methods: We conducted a cross-sectional electronic survey of ATA members' perspectives of these CPGs, using a standardized survey (Clinician Guidelines Determinant Questionnaire) developed by the Guidelines International Network. A survey link was electronically mailed to members in February of 2019, with reminders sent to nonrespondents 2 and 5 weeks later. Data were descriptively summarized, after excluding missing responses. Results: The overall response rate was 19.8% (348/1761). The effective response rate was 20.2% (348/1720), after excluding a recently deceased member and individuals who had either invalid e-mail addresses or whose e-mails were returned. Of the respondents, 37.9% (132/348) were female, 60.4% (209/346) were endocrinologists, 27.5% (95/346) were surgeons, and 3.5% (12/346) were nuclear medicine specialists. The majority of respondents (71.9%; 250/348) were at a mid- or advanced-career level, and more than half were in academia (57.5%; 195/339). The majority (69.8%; 243/348) practiced in North America. The vast majority of respondents indicated that the CPGs explained the underlying evidence (92.3%; 298/323) and 92.9% (300/323) agreed or strongly agreed with the content. Most respondents stated that they regularly used the CPGs in their practice (83.0%; 268/323). Most respondents (83.0%; 268/323) also agreed or strongly agreed that the recommendations were easy to incorporate in their practice. The most popular CPG format was an electronic desktop file (78.8%; 252/320). Shorter more frequent CPGs were favored by 55.0% (176/320) of respondents, and longer traditional CPGs were favored by 39.7% (127/320). Conclusions: The clinical content and evidence explanations in the adult TN and DTC CPGs are widely accepted and applied among ATA survey respondents. Future ATA CPG updates need to be optimized to best meet users' preferences regarding format, frequency, and length.

Performance of a Multigene Genomic Classifier in Thyroid Nodules With Indeterminate Cytology: A Prospective Blinded Multicenter Study

Question

Can the diagnosis of benign disease or cancer in thyroid nodules with indeterminate cytology be established by molecular testing instead of diagnostic surgery?

Findings

This prospective, blinded, multicenter cohort study of a multigene genomic classifier (ThyroSeq v3) test included 257 indeterminate cytology thyroid nodules with informative test results. It demonstrated a high sensitivity (94%) and reasonably high specificity (82%), with 61% of the nodules yielding a negative test result and only 3% residual cancer risk in these nodules.

Meanings

Up to 61% of patients with indeterminate cytology thyroid nodules may avoid diagnostic surgery by undergoing multigene genomic classifier testing.

Importance

Approximately 20% of fine-needle aspirations (FNA) of thyroid nodules have indeterminate cytology, most frequently Bethesda category III or IV. Diagnostic surgeries can be avoided for these patients if the nodules are reliably diagnosed as benign without surgery.

Objective

To determine the diagnostic accuracy of a multigene classifier (GC) test (ThyroSeq v3) for cytologically indeterminate thyroid nodules.

Design, Setting, and Participants

Prospective, blinded cohort study conducted at 10 medical centers, with 782 patients with 1013 nodules enrolled. Eligibility criteria were met in 256 patients with 286 nodules; central pathology review was performed on 274 nodules.

Interventions

A total of 286 FNA samples from thyroid nodules underwent molecular analysis using the multigene GC (ThyroSeq v3).

Main Outcomes and Measures

The primary outcome was diagnostic accuracy of the test for thyroid nodules with Bethesda III and IV cytology. The secondary outcome was prediction of cancer by specific genetic alterations in Bethesda III to V nodules.

Results

Of the 286 cytologically indeterminate nodules, 206 (72%) were benign, 69 (24%) malignant, and 11 (4%) noninvasive follicular thyroid neoplasms with papillary-like nuclei (NIFTP). A total of 257 (90%) nodules (154 Bethesda III, 93 Bethesda IV, and 10 Bethesda V) had informative GC analysis, with 61% classified as negative and 39% as positive. In Bethesda III and IV nodules combined, the test demonstrated a 94% (95% CI, 86%-98%) sensitivity and 82% (95% CI, 75%-87%) specificity. With a cancer/NIFTP prevalence of 28%, the negative predictive value (NPV) was 97% (95% CI, 93%-99%) and the positive predictive value (PPV) was 66% (95% CI, 56%-75%). The observed 3% false-negative rate was similar to that of benign cytology, and the missed cancers were all low-risk tumors. Among nodules testing positive, specific groups of genetic alterations had cancer probabilities varying from 59% to 100%.

Conclusions and Relevance

In this prospective, blinded, multicenter study, the multigene GC test demonstrated a high sensitivity/NPV and reasonably high specificity/PPV, which may obviate diagnostic surgery in up to 61% of patients with Bethesda III to IV indeterminate nodules, and up to 82% of all benign nodules with indeterminate cytology. Information on specific genetic alterations obtained from FNA may help inform individualized treatment of patients with a positive test result.

Molecular Diagnostic Evaluation of Thyroid Nodules

The historical management approach for many patients with indeterminate thyroid nodule fine needle aspiration cytology is a diagnostic lobectomy or thyroidectomy. However, the majority of patients undergo surgery unnecessarily, because most are proven to have benign disease on histology. Molecular testing is a diagnostic tool that can be used to help guide the clinical management of thyroid nodules with indeterminate cytology results. Testing has evolved substantially over the last decade with significant advances in testing methodology and improvements in our understanding of the genetic basis of thyroid cancer.

Comprehensive Genetic Characterization of Human Thyroid Cancer Cell Lines: A Validated Panel for Preclinical Studies

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.

Establishment and Characterization of Four Novel Thyroid Cancer Cell Lines and PDX Models Expressing the RET/PTC1 Rearrangement, BRAFV600E, or RASQ61R as Drivers

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.

American Head and Neck Society Endocrine Section clinical consensus statement: North American quality statements and evidence-based multidisciplinary workflow algorithms for the evaluation and management of thyroid nodules

BACKGROUND

Care for patients with thyroid nodules is complex and multidisciplinary, and research demonstrates variation in care. The objective was to develop clinical guidelines and quality metrics to reduce unwarranted variation and improve quality.

METHODS

Multidisciplinary expert consensus and modified Delphi approach. Source documents were workflow algorithms from Kaiser Permanente Northern California and Cancer Care of Ontario based on the 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer.

RESULTS

A consensus-based, unified preoperative, perioperative, and postoperative workflow was developed for North American use. Twenty-one panelists achieved consensus on 16 statements about workflow-embedded process and outcomes metrics addressing safety, access, appropriateness, efficiency, effectiveness, and patient centeredness of care.

CONCLUSION

A panel of Canadian and United States experts achieved consensus on workflows and quality metric statements to help reduce unwarranted variation in care, improving overall quality of care for patients diagnosed with thyroid nodules.

Outcomes of Bethesda categories III and IV thyroid nodules over 5 years and performance of the Afirma gene expression classifier: A single-institution study

OBJECTIVE

The second edition Bethesda System for Reporting Thyroid Cytology estimates 6%-18% malignancy rate of category III (B3) and 10%-40% for category IV (B4) nodules; however, reported malignancy rates have considerable variability among institutions. Use of molecular classifiers (including Afirma Gene Expression Classifier, GEC) can be utilized in management of thyroid nodules. Our objective was to analyse malignancy rates of B3 and B4 nodules and determine clinical outcomes of GEC Benign nodules.

METHODS

A retrospective analysis of 2019 thyroid FNAs was performed at the University of Colorado from 2011 to 2015, including molecular, surgical and clinical follow-up.

RESULTS

Of 2019 FNAs analysed, 231 (11.4%) were diagnosed as B3 and 80 (4.0%) as B4. GEC was obtained in 54.1% of B3 cases, with nearly half (48.8%) having a Benign result. Surgery was performed in 40.7% B3 cases with a 24.5% malignancy rate, ranging 8%-38% by year. In the B4 group, 52.5% underwent molecular testing with 28.6% as GEC Benign. About 68.8% of B4 cases underwent surgery with a 20% malignancy rate, ranging 0%-42% by year. Seventy-three GEC Benign cases were reviewed: 5 (6.8%) underwent surgery, with none demonstrating malignancy in the target nodule. Size remained stable for most GEC Benign nodules: 75.9% (B3) and 71.4% (B4) with no malignancy on repeat FNA.

CONCLUSIONS

Our 5-year review demonstrated that malignancy rates of B3 and B4 nodules showed year-to-year variability. We suggest that clinicians use a multi-year average of their institution's malignancy rates to optimally manage patients. Follow-up for GEC Benign cases thus far supports their indolent nature.