Programmed Death - Ligand 1 Expression Distinguishes Invasive Encapsulated Follicular Variant of Papillary Thyroid Carcinoma from Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features

Update regarding the role of PD-L1 in oncocytic thyroid lesions on cytological samples

AIMS

Several papers have shown that programmed death-ligand 1 (PD-L1) expression is a relevant predictive biomarker in anti-PD-L1 cancer immunotherapy. While its role in several human cancers is correlated with poor prognosis and resistance to anticancer therapies, in thyroid cancers the role of PD-L1 remains questionable. Few articles have studied PD-L1 in thyroid fine-needle aspiration cytology (FNAC), demonstrating a possible correlation with papillary thyroid carcinoma. However, its role in oncocytic thyroid lesions remains controversial. We accordingly examine the performance of PD-L1 immunostaining in liquid based cytology (LBC) from oncocytic lesions.

METHODS

From January 2019 to March 2021, 114 thyroid lesions diagnosed by FNAC from lesions with a predominant oncocytic component, were enrolled for evaluation by PD-L1 immunostaining on both LBC and corresponding histology samples.

RESULTS

The FNAC cohort included 51 benign (B, negative controls), 4 atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS), 57 follicular lesions (follicular neoplasm/suspicious for FN, FN/SFN) and 2 suspicious for malignancy (SFM) cases. Fifty-four cases (11B, 2 AUS/FLUS, 39 FN/SFN and 2 SFM) had histological follow-up including: 1B case resulted as a hyperplastic oxyphilic nodule in Hashimoto thyroiditis (HT), 10B as goitre, 2 AUS/FLUS cases as oncocytic adenomas (OAs); 39 FN/SFN included 27 OAs, 4 FA and 8 oncocytic follicular carcinoma (OFC). The two SFM cases were diagnosed on histopathology as OAs. Increased plasma membrane and cytoplasmic PD-L1 expression were found in 47 cases of the LBC cases (41.2%). Among the histological series, 67.3% of OAs and 75% of OFC had PD-L1 expression, while negative PD-L1 was found in hyperplastic oncocytic cells in HT. A positivity in more than 30% of the neoplastic cells was found in 72.9% of the cases including six OFC.

CONCLUSIONS

These data suggest that PD-L1 expression is expressed in oncocytic thyroid lesions. While weak PD-L1 expression failed to discriminate benign from malignant lesions, OFC demonstrated more intense cytoplasmic and membranous expression.

Hashimoto’s Thyroiditis Minimizes Lymph Node Metastasis in BRAF Mutant Papillary Thyroid Carcinomas

Hashimoto’s thyroiditis (HT) (autoimmune thyroiditis) is a clinicopathological entity associated with chronic lymphocytic infiltration resulting in hypothyroidism. HT is a double-edged sword that increases the risk of papillary thyroid cancer (PTC), yet it serves as a protective factor for PTC progression. BRAF mutation in PTCs is associated with rapid cell growth, aggressive tumor characteristics, and higher mortality rates. Here, we aimed to analyze the influence of HT in patients with PTCs and its effect on lymph node metastasis (LNM) in BRAF mutant tumors. Adults diagnosed with PTC between 2008 and January 2021 were retrospectively included. A total of 427 patients, 128 of whom had underlying HT, were included. The HT group had significantly higher rates of microcarcinoma (49.2% vs. 37.5%, p = 0.025) and less lateral LNM (8.6% vs. 17.1%, p = 0.024). Interestingly, BRAF-mutated PTCs were found to have significantly less overall LNM (20.9% vs. 51%, p = 0.001), central LNM (25.6% vs. 45.1%, p = 0.040) and lateral LNM (9.3% vs. 29.4%, p = 0.010) in patients with HT when compared to those without underlying HT. HT was found to be an independent protective predictor of overall and lateral LNM. Altogether, HT was able to neutralize the effect of BRAF mutation and was determined to be an independent protective factor against LNM. Specifically, our work may influence treatment-aggressiveness decision making for endocrinologists, oncologists and surgeons alike.

Combination Strategies Involving Immune Checkpoint Inhibitors and Tyrosine Kinase or BRAF Inhibitors in Aggressive Thyroid Cancer

Thyroid cancer is the most common (~90%) type of endocrine-system tumor, accounting for 70% of the deaths from endocrine cancers. In the last years, the high-throughput genomics has been able to identify pathways/molecular targets involved in survival and tumor progression. Targeted therapy and immunotherapy individually have many limitations. Regarding the first one, although it greatly reduces the size of the cancer, clinical responses are generally transient and often lead to cancer relapse after initial treatment. For the second one, although it induces longer-lasting responses in cancer patients than targeted therapy, its response rate is lower. The individual limitations of these two different types of therapies can be overcome by combining them. Here, we discuss MAPK pathway inhibitors, i.e., BRAF and MEK inhibitors, combined with checkpoint inhibitors targeting PD-1, PD-L1, and CTLA-4. Several mutations make tumors resistant to treatments. Therefore, more studies are needed to investigate the patient's individual tumor mutation burden in order to overcome the problem of resistance to therapy and to develop new combination therapies.

Analysis of anti-apoptotic PVT1 oncogene and apoptosis-related proteins (p53, Bcl2, PD-1, and PD-L1) expression in thyroid carcinoma

Background

An aberrant expression of long non‐coding RNA PVT1 has been associated with apoptosis in various cancer types. We aimed to explore the PVT1 and four apoptosis‐related proteins (p53, Bcl2, and PD‐1/PD‐L1) signature in thyroid cancer (TC).

Methods

The PVT1 expression level was measured in 64 FFPE TC paired samples by real‐time quantitative PCR. Overall and stratified analyses by different clinicopathological features were done. The apoptotic proteins were evaluated by immunohistochemistry staining.

Results

Overall analysis showed significant PVT1upregulation in TC tissues (p < 0.001). Similarly, subgroup analysis by BRAF^V600E mutation showed consistent results. Lower expression of p53 was associated with mortality (p = 0.001). Bcl2 overexpression was associated with greater tumor size (p = 0.005). At the same time, HCV‐positive cases were associated with repressed Bcl2 expression levels (54.3% in HCV‐negative vs. 6.9% in HCV‐positive cases, p = 0.011). PD‐1 expression was associated with lymph node metastasis (p = 0.004). Enhanced PD‐L1 expression in the tumor was associated with a higher tumor stage, lymphovascular invasion, and mortality risk. Kaplan–Meier curves for overall survival showed that low p53 and high PD‐L1 expressions were associated with lower survival time. The p53‐positive staining is associated with a 90% decreased mortality risk (HR = 0.10, 95%CI = 0.02–0.47, p = 0.001), while patients with high PD‐L1 were five times more likely to die (HR = 4.74, 95%CI = 1.2–18.7, p = 0.027).

Conclusion

Our results confirm the upregulation of PVT1 in TC. The apoptosis‐related proteins (p53, Bcl2, and PD‐1/PD‐L1) showed different prognostic utility in TC patients; in particular, low p53 and high PD‐L1 expressions associated with low survival times. Further large‐scale and mechanistic studies are warranted.

Non-invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP) lowers the risk of malignancy in the bethesda system for reporting thyroid cytopathology diagnostic categories

Background:

The introduction of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has been shown to decrease the risk of malignancy (ROM) in The Bethesda System for Reporting Thyroid Cytopathology. This knowledge may alter the management of patients with thyroid nodules.

Objectives:

To correlate cytological diagnosis with histological diagnosis for establishing the ROM of all Bethesda system categories after the introduction of NIFTP.

Methods:

This was a retrospective cohort study. All consecutive fine-needle aspiration cytology (FNAC) specimens collected from January 1, 2013, to December 31, 2017, at King Abdullah Medical City, Jeddah, Saudi Arabia, were assessed, and patients who underwent surgical excision of thyroid nodules were further analyzed. The ROM and overall ROM for each Bethesda category were calculated with and without considering NIFTP as a malignant tumor.

Results:

Overall, 1066 FNAC specimens were collected, of which 281 had a surgical correlation. Our cases included 18 (6.4%) non-diagnostic (ND), 109 (38.8%) benign, 28 (9.9%) atypia/follicular lesion of undetermined significance (AUS/FLUS), 39 (13.8%) follicular neoplasm or suspicion for follicular neoplasm (FN/SFN), 20 (7.1%) suspicion for malignancy (SM), and 67 (23.8%) malignant (POM) cases. After considering NIFTP diagnosis on resection specimens, the ROM decreased as follows: ND, 38.8% to 27.7% (P = 0.2388); benign, 21.1% to 11.9% (P = 0.0343); AUS/FLUS, 50% to 39.2% (P = 0.2089); FN/SFN, 53.8% to 33.3% (P = 0.0336); SM, 85% to 75% (P = 0.2147); POM, 95.5% to 88% (P = 0.0582).

Conclusion:

The introduction of NIFTP would significantly decrease the ROM of thyroid FNAC in both benign and FN/SFN categories of the Bethesda system.

Emerging roles of a pivotal lncRNA SBF2-AS1 in cancers

Long non-coding RNAs refer to transcripts over 200 nt in length that lack the ability to encode proteins, which occupy the majority of the genome and play a crucial role in the occurrence and development of human diseases, especially cancers. SBF2-AS1, a newly identified long non-coding RNA, has been verified to be highly expressed in diversiform cancers, and is involved in processes promoting tumorigenesis, tumor progression and tumor metastasis. Moreover, upregulation of SBF2-AS1 expression was significantly related to disadvantageous clinicopathologic characteristics and indicated poor prognosis. In this review, we comprehensively summarize the up-to-date knowledge of the detailed mechanisms and underlying functions of SBF2-AS1 in diverse cancer types, highlighting the potential of SBF2-AS1 as a diagnostic and prognostic biomarker and even a therapeutic target.

Non-cytomembrane PD-L1: An atypical target for cancer

Programmed death ligand 1 (PD-L1) has conventionally been considered as a type I transmembrane protein that can interact with its receptor, programmed cell death 1 (PD-1), thus inducing T cell deactivation and immune escape. However, targeting the PD-1/PD-L1 axis has achieved adequate clinical responses in very few specific malignancies. Recent studies have explored the extracellularly and subcellularly located PD-L1, namely, nuclear PD-L1 (nPD-L1), cytoplasmic PD-L1 (cPD-L1), soluble PD-L1 (sPD-L1), and extracellular vesicle PD-L1 (EV PD-L1), which might shed light on the resistance to anti-PD1/PDL1 therapy. In this review, we summarize the four atypical localizations of PD-L1 with a focus on their novel functions, such as gene transcription regulation, therapeutic efficacy prediction, and resistance to various cancer therapies. Additionally, we highlight that non-cytomembrane PD-L1s are of significant cancer diagnostic value and are promising therapeutic targets to treat cancer.

Diagnostic Value of Galectin-3 in Distinguishing Invasive Encapsulated Carcinoma from Noninvasive Follicular Thyroid Neoplasms with Papillary-Like Nuclear Features (NIFTP)

Simple Summary

The reclassification of NIFTP raised the need for rebuilding the clinical, histologic, cytological and molecular parameters, including re-evaluation of the previously examined biomarkers, for assisting in the diagnosis of this subset of indolent noninvasive tumors from invasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC). In this retrospective study, Galectin-3 (Gal-3) IHC staining on patient’s thyroid tissues showed a statistically significant higher cytoplasmic Gal-3 expression in invasive EFVPTC than in NIFTP and other benign subgroups. Our findings refined the diagnostic value of Gal-3 expression as an ancillary marker in identifying NIFTP among encapsulated follicular variant nodules.

Abstract

Background: non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), which is considered as low-risk cancer, should be distinguished from the malignant invasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC). Improved discrimination of NIFTPs from invasive EFVPTCs using a molecular biomarker test could provide useful insights into pre- and post-surgical management of the indeterminate thyroid nodule. Galectin-3 (Gal-3), a β-galactosyl-binding molecule in the lectin group, is involved in different biological functions in well differentiated thyroid carcinomas. The aim of this study was to determine whether Gal-3 expression as a diagnostic marker could distinguish indolent NIFTP from invasive EFVPTC on tissue specimens from surgical thyroid nodules. Methods: immunohistochemical (IHC) analysis of cytoplasmic and nuclear Gal-3 expression was performed in formalin-fixed paraffin-embedded (FFPE) surgical tissues in four specific diagnostic subgroups- benign nodules, NIFTPs, EFVPTCs and lymphocytic/Hashimoto’s thyroiditis (LTs). Results: cytoplasmic Gal-3 expression (mean ± SD) was significantly increased in invasive EFVPTCs (4.80 ± 1.60) compared to NIFTPs (2.75 ± 1.58, p < 0.001) and benign neoplasms (2.09 ± 1.19, p < 0.001) with no significant difference between NIFTPs and benign lesions (p = 0.064). The presence of LT enhanced cytoplasmic Gal-3 expression (3.80 ± 1.32) compared to NIFTPs (p = 0.016) and benign nodules (p < 0.001). Nuclear Gal-3 expression in invasive EFVPTCs (1.84 ± 1.30) was significantly higher than in NIFTPs (1.00 ± 0.72, p = 0.001), but similar to benign nodules (1.44 ± 1.77, p = 0.215), thereby obviating its potential clinical application. Conclusions: our observations have indicated that increased cytoplasmic Gal-3 expression shows diagnostic potential in distinguishing NIFTP among encapsulated follicular variant nodules thereby serving as a possible ancillary test to H&E histopathological diagnostic criteria when LT interference is absent, to assist in the detection of the invasive EFVPTC among such nodules.

Pathological findings of the retrospective diagnosis of NIFTP (non-invasive follicular thyroid neoplasm with papillary-like nuclear features) in 84 cases from Turkey and systematic review

AIM

The terminology of "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) was introduced in 2016; and estimated to cause significant effects in the clinical management of thyroid nodules. The aim of our study is to review our cases that were previously diagnosed as non-invasive encapsulated follicular variant PTC (NI/E-FVPTC) which are compatible with NIFTP and to correlate their follow-up.

METHOD

All thyroidectomy cases evaluated in the last 15 years were screened, and possible NIFTP cases were determined among patients with NI/E-FVPTC and they were re-examined microscopically. Revised histopathological criteria were used for the retrospective diagnosis of NIFTP. Histopathological findings were correlated to follow up information.

RESULTS

Totally 2138 cases had been previously diagnosed with PTC; 481 (22.5%) of them were FVPTC. After microscopic reevaluation of potential NIFTP cases, 84 cases (3.9%) received final diagnosis of NIFTP. 78.6% of NIFTP patients were female (F/M: 66/18); mean age was 49.0, tumor diameter was 22.7 mm and follow-up time was 66.4 months. 17.9% of NIFTP cases were multifocal and 13.1% were bilateral. No recurrence, lymph node involvement or distant metastasis was detected in any of the patients who were followed up. The mean age of the patients who had total thyroidectomy and received RAI was significantly higher than those who did not.

CONCLUSION

Although conservative treatment of NIFTP with lobectomy is recommended, age of the patients has been continuing to be the most important determinant for the clinicians to decide on total thyroidectomy and RAI ablation therapy at our institution.

Peripheral Versus Intraparenchymal Papillary Thyroid Microcarcinoma: Different Morphologies and PD-L1 Expression

Peripheral localisation of papillary thyroid microcarcinoma (PTMC), in comparison with intraparenchymal PTMC (i-PTMC) is related to some clinicopathological features related with biological aggressiveness, including lymph node metastasis (LNM). The expression of PD-L1 in tumour cell has been associated with increased tumour survival, progression, and potentially an aggressive clinical course. This study evaluates the relation between clinicopathological features of PTMC, including tumour localisation, with PD-L1 immunoexpression. The study included 99 patients with the histological diagnosis of PTMC (≥ 5 mm). PD-L1 protein expression was assessed by immunohistochemistry. PTMCs were divided into the four following groups: G1- peripherally localised PTMC (p-PTMC) with PD-L1 expression; G2-p-PTMC without PD-L1 expression; G3-i-PTMC with PD-L1 expression and G4-i-PTMC without PD-L1 expression. G1 was the most frequent (n = 46; 46.5%), followed by G4 (n = 25; 25.3%) and similar distribution of G3 (n = 15; 15.2%) and G2 (n = 13; 13.1%). In comparison with other groups, G1 was significantly associated with classical morphology, invasive growth, lymphatic invasion (LI), vascular invasion (VI), psammoma bodies, intratumoral fibrosis, PD-L1 positive tumour-infiltrating lymphocytes, and multinuclear giant cells (MGCs). G4 more commonly exhibited follicular morphology, expansive/circumscribed growth, and absence of the following: intratumoural fibrosis, LI, VI, psammoma bodies, PD-L1 positive tumour-infiltrating lymphocytes, and MGCs. LNMs were significantly more frequent in G1 in comparison with the other groups (p = 0.000). In conclusion, morphology and tumour microenvironment of p-PTMC with PD-L1 expression is different from i-PTMC without PD-L1 expression. The differences between these two groups of PTMC include clinicopathological features related with biological aggressiveness such as the occurrence of LNM.

Actions of Thyroid Hormones on Thyroid Cancers

L-Thyroxine (T4) is the principal ligand of the thyroid hormone analogue receptor on the extracellular domain of integrin αvβ3. The integrin is overexpressed and activated in cancer cells, rapidly dividing endothelial cells, and platelets. The biologic result is that T4 at physiological concentration and without conversion to 3,3',5-triiodo-L-thyronine (T3) may stimulate cancer cell proliferation and cancer-relevant angiogenesis and platelet coagulation. Pro-thrombotic activity of T4 on platelets is postulated to support cancer-linked blood clotting and to contribute to tumor cell metastasis. We examine some of these findings as they may relate to cancers of the thyroid. Differentiated thyroid cancer cells respond to physiological levels of T4 with increased proliferation. Thus, the possibility exists that in patients with differentiated thyroid carcinomas in whom T4 administration and consequent endogenous thyrotropin suppression have failed to arrest the disease, T4 treatment may be stimulating tumor cell proliferation. In vitro studies have shown that tetraiodothyroacetic acid (tetrac), a derivative of T4, acts via the integrin to block T4 support of thyroid cancer and other solid tumor cells. Actions of T4 and tetrac or chemically modified tetrac modulate gene expression in thyroid cancer cells. T4 induces radioresistance via induction of a conformational change in the integrin in various cancer cells, although not yet established in thyroid cancer cells. The thyroid hormone receptor on integrin αvβ3 mediates a number of actions of T4 on differentiated thyroid cancer cells that support the biology of the cancer. Additional studies are required to determine whether T4 acts on thyroid cancer cells.

From biomarkers to therapeutic targets: the promise of PD-L1 in thyroid autoimmunity and cancer

The programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) immune checkpoint proteins hold promise as diagnostic, prognostic, and therapeutic targets for precision oncology. By restoring antitumor T cell surveillance, the high degree of effectiveness of the immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment. However, the majority of patients (65-80 %) treated with ICIs experience significant side effects, called immune-related adverse events (irAEs), resulting in autoimmune damage to various organs. Therefore, broadening the clinical applicability of these treatments to all cancer types requires an improved understanding of the mechanisms linking cancer immune evasion and autoimmunity. The thyroid is the endocrine gland the most frequently involved in autoimmunity and cancer, the growing incidence of which is raising serious public health issues worldwide. In addition, the risk of developing thyroid cancer is increased in patients with autoimmune thyroid disease and thyroid dysfunction is one of the most common irAEs, especially with PD‑1/PD-L1 blockade. Therefore, we chose the thyroid as a model for the study of the link between autoimmunity, irAEs, and cancer. We provide an update into the current knowledge of the PD‑1/PD-L1 axis and discuss the growing interest of this axis in the diagnosis, prognosis, and management of thyroid diseases within the context of autoimmunity and cancer, while embracing personalized medicine.

Novel Therapeutics in Radioactive Iodine-Resistant Thyroid Cancer

Iodine-resistant cancers account for the vast majority of thyroid related mortality and, until recently, there were limited therapeutic options. However, over the last decade our understanding of the molecular foundation of thyroid function and carcinogenesis has driven the development of many novel therapeutics. These include FDA approved tyrosine kinase inhibitors and small molecular inhibitors of VEGFR, BRAF, MEK, NTRK and RET, which collectively have significantly changed the prognostic outlook for this patient population. Some therapeutics can re-sensitize de-differentiated cancers to iodine, allowing for radioactive iodine treatment and improved disease control. Remarkably, there is now an FDA approved treatment for BRAF-mutated patients with anaplastic thyroid cancer, previously considered invariably and rapidly fatal. The treatment landscape for iodine-resistant thyroid cancer is changing rapidly with many new targets, therapeutics, clinical trials, and approved treatments. We provide an up-to-date review of novel therapeutic options in the treatment of iodine-resistant thyroid cancer.

Primary squamous cell carcinoma of thyroid with a novel BRAF mutation and High PDL-1 expression: A case report with treatment implications and review of literature

Primary squamous cell carcinoma of thyroid (SCC-T) is an extremely rare, aggressive neoplasm with median survival of 9 months. Pure squamous morphology with absence of other cell types is required for diagnosis of SCC-T. Clinically, SCC-T behaves like anaplastic thyroid carcinoma (ATC) showing rapid growth, and extra thyroidal extension. We report a 91-year-old woman presenting with an enlarging thyroid mass and accompanying dysphagia and hoarseness. Fine needle aspiration revealed hypercellular specimen with large, pleomorphic, malignant cells. Intraoperative assessment revealed an inoperable tumor involving both thyroid lobes and extensively infiltrating surrounding soft tissues. A subtotal thyroidectomy was performed. Histology revealed squamous cell carcinoma replacing native thyroid tissue and infiltrating adjacent skeletal muscle. Lymphovascular and perineural invasion were present. Immunohistochemistry showed tumor cells positive for CK5-p40, Pax-8, TTF-1 and negative for thyroglobulin. P53 expression by IHC was high and Ki-67 proliferation index was > 90 %. (Next generation sequencing revealed a novel BRAF mutation (BRAF c.1799 T > A; 1801_1812del) along with TP53 and TERT mutations. PDL-1 immunohistochemistry showed positive expression in tumor cells (>80%), making patient also amenable to anti-PDL-1 immunotherapy. Patient was treated with BRAF inhibitor therapy with initial relief but eventually was put on hospice care due to increasing intolerance to therapy. This case represents a rare thyroid malignancy with a unique molecular signature consisting of a novel BRAF mutation [previously not described in SCC-T or ATC], associated with TERT-TP53 mutations. Further, importance of PDL-1 testing as a prognostic marker and as a guide to immunotherapy in refractory tumors is discussed.

Novel Targeted Therapies for Metastatic Thyroid Cancer-A Comprehensive Review

The knowledge on thyroid cancer biology has grown over the past decade. Thus, diagnostic and therapeutic strategies to manage thyroid cancer are rapidly evolving. With new insights into tumor biology and cancer genetics, several novel therapies have been approved for the treatment of thyroid cancer. Tyrosine kinase inhibitors (TKIs), such as lenvatinib and sorafenib, have been successfully utilized for the treatment of radioactive iodine (RAI)-refractory metastatic differentiated thyroid cancer (DTC). In addition, pretreatment with mitogen-activated protein kinase (MAPK) inhibitors (trametinib and selumetinib) has been shown to restore RAI avidity in previously RAI-refractory DTCs. Local therapies, such as external beam radiation and radiofrequency/ethanol ablation, have also been employed for treatment of DTC. Vandetanib and cabozantinib are the two TKIs currently approved by the Food and Drug Administration (FDA) for the treatment of medullary thyroid cancer (MTC). Other novel therapies, such as peptide receptor radionuclide therapy and carcinoembryonic antigen (CEA) vaccine, have also been utilized in treating MTC. Ongoing trials on selective rearranged-during-transfection (RET) protooncogene inhibitors, such as LOXO-292 and BLU-667, have demonstrated promising results in the treatment of metastatic MTC resistant to non-selective TKIs. The FDA-approved BRAF/MEK inhibitor combination of dabrafenib and trametinib has revolutionized treatment of BRAFV600E mutation positive anaplastic thyroid cancer. Several other emerging classes of medications, such as gene fusion inhibitors and immune checkpoint inhibitors, are being actively investigated in several clinical trials. In this review, we describe the molecular landscape of thyroid cancer and novel targeted therapies and treatment combinations available for the treatment of metastatic thyroid cancer.

MicroRNA‑15b‑5p exerts its tumor repressive role via targeting GDI2: A novel insight into the pathogenesis of thyroid carcinoma

Thyroid carcinoma (THCA) is a malignant tumor of the endocrine system. Previous studies have revealed the vital roles of microRNAs (miRNAs/miRs) in THCA procession. The present study aimed to explore the effects of miR-15b-5p on the progression of THCA and its targeting mechanism. The data of THCA and healthy samples were firstly collected from starbase2.0 and used to analyze the relationship of miR-15b-5p with THCA. Dual-luciferase assay was performed to detect the direct interaction between miR-15b-5p and the predicted target gene GDP dissociation inhibitor 2 (GDI2). The effects of miR-15b-5p and GDI2 on the overall survival of patients with THCA were analyzed using Kaplan-Meier analysis with log rank test. Cell Counting Kit-8 and Transwell assays were conducted to assess the impacts of miR-15b-5p and GDI2 on the proliferation and invasion of THCA cells. Reverse transcription-quantitative PCR and western blot analyses were performed to analyze the expression levels of the related miRNAs and proteins, respectively. miR-15b-5p was found to be downregulated both in THCA tissues and cells, and the low expression of miR-15b-5p was associated with the short overall survival time of patients. Moreover, the upregulation or downregulation of miR-15b-5p could inhibit or enhance the proliferation and invasion of THCA cells, respectively. miR-15b-5p reduced the protein expression levels of matrix metalloproteinase (MMP)2 and MMP9, which were related to cell invasion. Furthermore, GDI2, which was enhanced in THCA and related to the poor prognosis of patients with THCA, was identified as the target gene of miR-15b-5p and negatively regulated by miR-15b-5p. Additional experiments demonstrated that GDI2 overexpression could significantly reduce the antitumor effect of miR-15b-5p and its inhibitory action on the expression levels of MMP2 and MMP9. Thus, the results indicated a potential tumor suppressive role of miR-15b-5p in THCA, which was mainly exerted by targeting GDI2 and modulating MMP2 and MMP9. These findings will increase the understanding on the pathogenesis of THCA and provide novel candidates for THCA therapy.

Regression of Papillary Thyroid Cancer during Nivolumab for Renal Cell Cancer

Immune checkpoint inhibitors have been recently approved for cancer treatment. Nivolumab is a monoclonal antibody specific for programmed cell death-1 (PD-1) that modulates T-cell response. It was initially used for the treatment of malignant melanoma and then approved in other cancers, such as non-small cell lung cancer and clear cell renal cell carcinoma (ccRCC). So far, the activity of nivolumab in patients with thyroid malignancies has been reported in a single case of anaplastic thyroid cancer. Here, we report the case of a patient with ccRCC who developed a papillary thyroid carcinoma (PTC) under first-line sunitinib treatment. During nivolumab, the second-line treatment for ccRCC, we unexpectedly observed a complete regression of PTC.

Clinical roles of miR-136-5p and its target metadherin in thyroid carcinoma

BACKGROUND

Thyroid carcinoma (TC) is a common malignancy of the endocrine system. This research aimed to examine the expression levels of miR-136-5p and metadherin (MTDH) in TC and unveil their potential targeting relationship.

METHODS

TC microRNA (miRNA) microarray and miRNA-sequencing data were collected to evaluated miR-136-5p expression. We assessed the comprehensive expression of miR-136-5p by calculating the standard mean difference (SMD) and summary receiver operating characteristic curves (sROC). Subsequently, the miR-136-5p mimic and inhibitor were transfected into the TC B-CPAP cell, Thiazolyl Blue Tetrazolium Bromide (MTT) assay and cell apoptosis assay by FACS with Annexin V-/7-AAD double staining were performed to explore the biological role of miR-136-5p in the B-CPAP cell line. Prediction of target genes and potential biological function analysis of miR-136-5p were made using miRWalk2.0 and DAVID, respectively. Through target gene prediction, MTDH may be the candidate target gene of miR-136-5p. Subsequently, gene microarrays and RNA-sequencing data were also leveraged for MTDH expression. The meta-analysis method was conducted to evaluate the comprehensive expression level of MTDH. In addition, MTDH protein expression was identified using immunohistochemistry. The MTDH protein levels post-miR-136-5p transfection were verified by western blot, and the dual luciferase reporter assay was adapted to confirm the direct targeting relation between miR-136-5p and MTDH.

RESULTS

The miR-136-5p level was remarkably downregulated in TC, the pooled SMD was -0.47 (95% CI: -0.70 to -0.23, I²=36.6%, P=0.192) and the area under the curve (AUC) of the sROC was 0.67 based on 543 cases of TC. MTT indicated that the overexpression of miR-136-5p dramatically inhibited the proliferation of B-CPAP cells. The cell apoptosis increased in the miR-136-5p mimic group compared to the negative control group. In addition, both MTDH mRNA and protein levels were markedly overexpressed, with the pooled SMD being 0.94 (95% CI: -0.35 to 2.24, I²=98.8%, P<0.001), and the AUC of the sROC being 0.85 with 1054 cases of TC. The MTDH protein level was significantly up-regulated in TC than in the non-carcinomic tissues by immunohistochemistry (8.292±1.717 vs. 2.618±2.570, P<0.001). Western blot indicated that MTDH protein expression was suppressed by miR-136-5p mimic in the B-CPAP cell line, which was further supported by the dual luciferase reporter assay.

CONCLUSION

The miR-136-5p/MTDH axis may play a vital role in modulating TC tumorigenesis, providing new insight into possible molecular mechanisms of TC oncogenesis.

Non-invasive follicular thyroid neoplasm with papillary-like nuclearfeatures (NIFTP): a review and update

BACKGROUND

The nomenclature "Non-invasive Follicular Neoplasm with Papillary-like Nuclear Features (NIFTP)" was introduced in 2016. While NIFTP differs from classic papillary thyroid carcinoma (PTC) in imaging, cytomorphology, histology, molecular profile, treatment, follow up, outcome, and behavior, it largely overlaps with follicular variant of PTC at imaging and cytomorphology. Herein, we review the literature for better understanding NIFTP, and its impact on patient care.

METHODS

The English literature was thoroughly evaluated with the key word of "Noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP)".

OBSERVATIONS

NIFTP presents as a thyroid nodule. On imaging, it is a round-to-oval, well circumscribed mass with solid internal content. Aspirated material shows a microfollicular pattern with focal nuclear features of PTC mostly reported in categories 3-5 of the Bethesda System for Reporting Thyroid Cytology (TBRSTC). NIFTP has decreased risk of malignancy in TBRSTC categories 3-6. Histologic examination of NIFTP reveals an encapsulated neoplasm with follicular pattern and nuclear features of PTC with no capsular or vascular invasion. No papillary structure, atypia, or mitosis is present. In contrast to PTC, only 4% of NIFTP cases harbor a BRAF mutation. Because NIFTP carries an excellent prognosis and indolent behavior, the tumor behavior was changed from malignant to a neoplasm with tumor with extremely indolent behavior. The recommended treatment is lobectomy with no further ablation therapy. Until better understanding of NIFTP, patient's follow up should be occasionally performed by neck ultrasonography and serum thyroglobulin measurement.

CONCLUSION

NIFTP carries an excellent prognosis. It is critical for both clinicians and patients to be aware of extremely indolent behavior of NIFTP in order to prevent unnecessary, aggressive treatment.

Needle Biopsy Adequacy in the Era of Precision Medicine and Value-Based Health Care

CONTEXT.—

Needle biopsy of diseased tissue is an essential diagnostic tool that is becoming even more important as precision medicine develops. However, the capability of this modality to efficiently provide samples adequate for diagnostic and prognostic analysis remains quite limited relative to current diagnostic needs. For physicians and patients, inadequate biopsy frequently leads to diagnostic delay, procedure duplication, or insufficient information about tumor biology leading to delay in treatment; for health systems, this results in substantial incremental costs and inefficient use of scarce specialized diagnostic resources.

OBJECTIVE.—

To review current needle biopsy technology, devices, and practice with a perspective to identify current limitations and opportunities for improvement in the context of advancing precision medicine.

DATA SOURCES.—

PubMed searches of fine-needle aspiration and core needle biopsy devices and similar technologies were made generally, by tissue site, and by adequacy as well as by health economics of these technologies.

CONCLUSIONS.—

Needle biopsy adequacy can be improved by recognizing the importance of this diagnostic tool by promoting common criteria for needle biopsy adequacy; by optimizing needle biopsy procedural technique, technologies, clinical practice, professional education, and quality assurance; and by bundling biopsy procedure costs with downstream diagnostic modalities to provide better accountability and incentives to improve the diagnostic process.

PD-1 Ligand Expression in Epithelial Thyroid Cancers: Potential Clinical Implications

The new immunotherapy targeting the programmed cell death 1 (PD-1) receptor and its cognate ligand PD-L1 has renewed hopes of eradicating the most difficult human cancers to treat. Among these, there are the poorly differentiated and anaplastic thyroid cancers, unresponsive to all the therapies currently in use. In the present review we will summarize information regarding the expression of PD-L1 in the different thyroid cancer histotypes, its correlation with clinicopathological features, and its potential prognostic value. Then, we will evaluate the available data indicating the PD-1/PD-L1 axis as a promising target for thyroid cancer therapy.

Cytomorphology of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features and the Impact of New Nomenclature on Molecular Testing

The re-naming of noninvasive follicular variant papillary thyroid cancer to the apparently non-malignant, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) impacts the prevalence of malignancy rates, thereby affecting mutation frequency in papillary thyroid cancer. Preoperative assessment of such nodules could affect management in the future. The original publications following the designation of the new nomenclature have been extensively reviewed. With the adoption of NIFTP terminology, a reduction in the follicular variant of papillary thyroid cancer (FVPTC) prevalence is anticipated, as is a modest reduction of papillary thyroid cancer (PTC) prevalence that would be distributed mainly across indeterminate thyroid nodules. Identifying NIFTP preoperatively remains challenging. RAS mutations are predominant but the presence of BRAF V600E mutation has been observed and could indicate inclusion of the classical PTC. The histological diagnosis of NIFTP to designate low-risk encapsulated follicular variant papillary thyroid cancers (EFVPTCs) would impact malignancy rates, thereby altering the mutation prevalence. The histopathologic criteria have recently been refined with an exclusion of well-formed papillae. The preoperative identification of NIFTP using cytomorphology and gene testing remains challenging.

Development of a prognostic index based on an immunogenomic landscape analysis of papillary thyroid cancer

BACKGROUND

Papillary thyroid cancer (PTC) is the most common subtype of thyroid cancer, and inflammation relates significantly to its initiation and prognosis. Systematic exploration of the immunogenomic landscape therein to assist in PTC prognosis is therefore urgent. The Cancer Genome Atlas (TCGA) project provides a large number of genetic PTC samples that enable a comprehensive and reliable immunogenomic study.

METHODS

We integrated the expression profiles of immune-related genes (IRGs) and progression-free intervals (PFIs) in survival in 493 PTC patients based on the TCGA dataset. Differentially-expressed and survival-associated IRGs in PTC patients were estimated a computational difference algorithm and COX regression analysis. The potential molecular mechanisms and properties of these PTC-specific IRGs were also explored with the help of computational biology. A new prognostic index based on immune-related genes was developed by using multivariable COX analysis.

RESULTS

A total of 46 differentially expressed immune-related genes were significantly correlated with clinical outcome of PTC patients. Functional enrichment analysis revealed that these genes were actively involved in a cytokine-cytokine receptor interaction KEGG pathway. A prognostic signature based on RGs (AGTR1, CTGF, FAM3B, IL11, IL17C, PTH2R and SPAG11A) performed moderately in prognostic predictions and correlated with age, tumor stage, metastasis, number of lesions, and tumor burden. Intriguingly, the prognostic index based on IRGs reflected infiltration by several types of immune cells.

CONCLUSIONS

Together, our results screened several IRGs of clinical significance, revealed drivers of the immune repertoire, and demonstrated the importance of a personalized, IRG-based immune signature in the recognition, surveillance, and prognosis of PTC.

Papillary Thyroid Carcinoma Emerging from Hashimoto Thyroiditis Demonstrates Increased PD-L1 Expression, Which Persists with Metastasis

There is evidence that programmed death-ligand 1 (PD-L1) is expressed by thyroid follicular epithelium in thyroiditis, but the role of PD-L1 in papillary thyroid carcinoma (PTC) is poorly understood. We aimed to determine whether (1) the presence of background chronic lymphocytic thyroiditis (CLT) or Hashimoto thyroiditis (HT) influenced the expression of PD-L1 in benign follicular epithelium or in PTC and (2) if PD-L1 expression in PTC persisted with lymph node metastasis. We performed immunohistochemistry (IHC) for PD-L1 on formalin-fixed paraffin-embedded tissues. We first studied five cases of unremarkable thyroid, five cases of CLT, and five cases of HT without carcinoma. We subsequently performed PD-L1 IHC on ten cases of PTC arising in normal thyroid, ten cases of PTC arising in CLT, and ten cases of PTC arising in HT. Whenever available, we evaluated corresponding synchronous lymph node metastases from all cases for PD-L1 expression. PD-L1 expression was increased (10-90%) in all five cases of HT, only minimal expressed (1-5%) in two of five cases of CLT, and not expressed in five cases of unremarkable thyroid. PTC arising in normal thyroid or CLT nearly uniformly lacked PD-L1 expression. In contrast, PTC arising in HT demonstrated significant PD-L1 expression, which persisted in corresponding lymph node metastases. Background non-neoplastic follicular epithelium in the HT cases also demonstrated PD-L1 expression. Thyroid follicular epithelium in HT demonstrates increased PD-L1 expression, and PTC arising in a background of HT shows increased PD-L1 expression, which is retained with metastasis.

Does Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features (NIFTP) Have a Unique Molecular Profile?

OBJECTIVES

Recognizing preoperative characteristics of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is important for clinical management. Therefore, we assessed presurgical NIFTP molecular profiles using fine-needle aspiration (FNA) material.

METHODS

Presurgical FNA reports of 39 surgically confirmed NIFTP cases from January 2013 through May 2017 were assessed for Afirma and ThyroSeq results.

RESULTS

Twenty-one of 39 NIFTP nodules were preoperatively tested with Afirma with two benign and 19 suspicious results. Twenty-seven of 39 nodules were tested with ThyroSeq (nine of 39 had both Afirma and Thyroseq): 18 (67%) had RAS mutations (13 NRAS, four HRAS, one KRAS), and three of 18 had multiple alterations (NRAS + TP53, n = 1; NRAS + PTEN, n = 2). BRAF T599_R603 + EIF1AX mutation (n = 1), PTEN mutation (n = 1), MET overexpression (n = 1), PAX8/PPARG fusion (n = 3), and THADA/IGF2BP3 fusion (n = 3) comprised the remainder.

CONCLUSIONS

NIFTP cases most commonly displayed suspicious Afirma results and RAS mutations on ThyroSeq, lacking aggressive/BRAF-V600E-like mutations. While NIFTP remains a surgical entity, the lack of aggressive/BRAF-V600E-like mutations can aid in determining the extent of surgery.

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: Can Cytology Face the Challenge of Diagnosis in the Light of the New Classification?

OBJECTIVES

To assess the cytological findings of noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), conventional papillary thyroid carcinomas (C-PTC), and invasive follicular variants of papillary thyroid carcinomas (IFV-PTC) to determine if there are cytological differences between groups.

STUDY DESIGN

We have reviewed all thyroid fine-needle aspiration cytology samples diagnosed between 2000 and 2017. We have included all NIFTP cases (n = 6) and randomly selected cases of C-PTC (n = 14) and IFV-PTC (n = 8).

RESULTS

Comparing NIFTP and C-PTC cases, NIFTP cases showed significantly less papillary or pseudopapillary architecture, more bidimensional groups and microfollicles, and less tridimensionality, giant cells, and nuclear folds. We observed a trend towards significance for smear cellularity and amount of cytoplasm. Presence of nuclear folds was the only significant difference between NIFTP and IFV-PTC cases. The differences between groups in percent papillary or pseudopapillary architecture, cellularity, and tridimensionality showed a trend towards significance. Amount of colloid, dirty background, pleomorphism or atypia, nuclear pseudoinclusions, type of chromatin, and nucleolus were not significant.

CONCLUSIONS

No cytopathological feature can differentiate between invasive and encapsulated IFV-PTC. In accordance with the recently accepted category, PTC smears with cells arranged in a predominantly follicular architecture should be reported as Bethesda IV category with descriptive terms to avoid false-positive cases.

Programmed death-ligand 1 expression by digital image analysis advances thyroid cancer diagnosis among encapsulated follicular lesions

Recognition of noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) that distinguishes them from invasive malignant encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) can prevent overtreatment of NIFTP patients. We and others have previously reported that programmed death-ligand 1 (PD-L1) is a useful biomarker in thyroid tumors; however, all reports to date have relied on manual scoring that is time consuming as well as subject to individual bias. Consequently, we developed a digital image analysis (DIA) protocol for cytoplasmic and membranous stain quantitation (ThyApp) and evaluated three tumor sampling methods [Systemic Uniform Random Sampling, hotspot nucleus, and hotspot nucleus/3,3'-Diaminobenzidine (DAB)]. A patient cohort of 153 cases consisting of 48 NIFTP, 44 EFVPTC, 26 benign nodules and 35 encapsulated follicular lesions/neoplasms with lymphocytic thyroiditis (LT) was studied. ThyApp quantitation of PD-L1 expression revealed a significant difference between invasive EFVPTC and NIFTP; but none between NIFTP and benign nodules. ThyApp integrated with hotspot nucleus tumor sampling method demonstrated to be most clinically relevant, consumed least processing time, and eliminated interobserver variance. In conclusion, the fully automatic DIA algorithm developed using a histomorphological approach objectively quantitated PD-L1 expression in encapsulated thyroid neoplasms and outperformed manual scoring in reproducibility and higher efficiency.

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP): impact on the reclassification of thyroid nodules

The 2017 edition of the WHO book on Classification of Tumours of Endocrine Organs includes a new section entitled 'Other encapsulated follicular-patterned thyroid tumours', in which the newly created NIFTP (non-invasive follicular thyroid neoplasm with papillary-like nuclear features) is identified and described in detail. Despite deleting the word 'carcinoma' from its name, NIFTP is not a benign tumor either and is best regarded as a neoplasm with 'very low malignant potential'. The main goal of the introduction of NIFTP category is to prevent overdiagnosis and overtreatment. Sampling constraints, especially when dealing with heterogeneous and/or large nodules, and difficulties in the invasiveness evaluation, are the major weaknesses of the histological characterization of NIFTP. At the cytological level, NIFTP can be separated from classic papillary carcinoma (cPTC) but not from encapsulated, invasive follicular variant PTC. The impact of NIFTP individualization for cytopathology is the drop of rates of malignancy for each Bethesda category in general and for indeterminate categories in particular. The biggest impact will be seen in institutions with a high frequency of FVPTC. The introduction of NIFTP has changed the utility of predictive values of molecular tests because RAS mutations and PAX8-PPARg rearrangements are frequently detected in NIFTP. This turns less promising the application of mutation detection panels as indicators of malignancy and will probably contribute to switch to a rule-out approach of molecular testing. Selection for surgery will go on being determined by a combined detection of clinical, cytological and ultrasound suspicious features.