Targeted Therapy for Medullary Thyroid Cancer: A Review

An Illustrated Review of the Recent 2019 World Health Organization Classification of Neuroendocrine Neoplasms: A Radiologic and Pathologic Correlation

ABSTRACT

Recent advances in molecular pathology and an improved understanding of the etiology of neuroendocrine neoplasms (NENs) have given rise to an updated World Health Organization classification. Since gastroenteropancreatic NENs (GEP-NENs) are the most common forms of NENs and their incidence has been increasing constantly, they will be the focus of our attention. Here, we review the findings at the foundation of the new classification system, discuss how it impacts imaging research and radiological practice, and illustrate typical and atypical imaging and pathological findings. Gastroenteropancreatic NENs have a highly variable clinical course, which existing classification schemes based on proliferation rate were unable to fully capture. While well- and poorly differentiated NENs both express neuroendocrine markers, they are fundamentally different diseases, which may show similar proliferation rates. Genetic alterations specific to well-differentiated neuroendocrine tumors graded 1 to 3 and poorly differentiated neuroendocrine cancers of small cell and large-cell subtype have been identified. The new tumor classification places new demands and creates opportunities for radiologists to continue providing the clinically most relevant report and on researchers to design projects, which continue to be clinically applicable.

Changes in Drug Clinical Trials of Thyroid Diseases in China, 2009-2022

OBJECTIVE

The incidence rate of thyroid diseases increased worldwide. This study aims to overview the changing landscape of drug clinical trials on thyroid disease during 2009-2022.

METHODS

The detailed information of thyroid disease drug trials registered on the National Medical Products Administration (NMPA) Registration and Information Disclosure Platform for Drug Clinical Studies was searched and collected. The thyroid drug clinical trials were analyzed by the characteristics, time trends, indications, and geographical distribution.

RESULTS

Sixty-five thyroid disease drug clinical trials were launched from 2009 to 2022 in China, which included 21 trials in nontumorous thyroid disease and 44 trials in thyroid carcinoma. The number of registered trials of thyroid diseases including thyroid carcinoma and nontumorous thyroid disease increased steadily from 2009 to 2020. Bioequivalence studies accounted for the largest proportion (32[49.2%]), while phase I and Phase II studies both only accounted for 18.5% (12/65). A significant difference was observed in the trials phase, and randomization between thyroid carcinoma and nontumorous thyroid disease. In terms of clinical indications and drug mechanisms, the number of trials in multi-target tyrosine kinase inhibitors for thyroid carcinoma (n=35) ranked first, followed by thyroid hormone for hypothyroidism (n=7), thyrotropin for thyroid carcinoma (n=6). Sixty-five trials were led by 36 principal investigator (PI) units, and more than 30% of PI-leading units were located in Shanghai (n=7) and Beijing (n=4).

CONCLUSION

During the past 13 years, the development of thyroid diseases drugs trials has achieved certain progress in thyroid carcinoma, especially the molecular targeted therapy, yet the development of drug trials on nontumorous thyroid disease was very slow.

Medullary thyroid carcinoma

INTRODUCTION

Medullary thyroid carcinoma (MTC) constitutes approximately 5-10% of all thyroid cancers. Although the tumor forms in the thyroid, it doesn't originate from thyroid cells, but from the C cells or parafollicular cells which produce and release a hormone called calcitonin (CT). Starting from the second half of the 1900s, MTC was progressively studied and defined.

AREAS COVERED

This study aims to analyze the history, clinical presentation and biological behavior of MTC, bio-humoral and instrumental diagnosis, molecular profiling, genetic screening, preoperative staging and instrumental procedures, indispensable in expert and dedicated hands, such as high-resolution ultrasonography, CT-scan, MRI and PET/TC. We examine recommended and controversial surgical indications and procedures, prophylactic early surgery and multiple endocrine neoplasia surgery. Also, we discuss pathological anatomy classification and targeted therapies. The role of serum CT is valued both as undisputed and constant preoperative diagnostic marker, obscuring cytology and as early postoperative marker that predicts disease persistence.

EXPERT OPINION

With a complete preoperative study, unnecessary or useless, late and extended interventions can be reduced in favor of tailored surgery that also considers quality of life. Finally, great progress has been made in targeted therapy, with favorable impact on survival.

Voltage-Gated Sodium Channel NaV1.7 Inhibitors with Potent Anticancer Activities in Medullary Thyroid Cancer Cells

Our results from quantitative RT-PCR, Western blotting, immunohistochemistry, and the tissue microarray of medullary thyroid cancer (MTC) cell lines and patient specimens confirm that VGSC subtype NaV1.7 is uniquely expressed in aggressive MTC and not expressed in normal thyroid cells and tissues. We establish the druggability of NaV1.7 in MTC by identifying a novel inhibitor (SV188) and investigate its mode of binding and ability to inhibit INa current in NaV1.7. The whole-cell patch-clamp studies of the SV188 in the NaV1.7 channels expressed in HEK-293 cells show that SV188 inhibited the INa current in NaV1.7 with an IC50 value of 3.6 µM by a voltage- and use-dependent blockade mechanism, and the maximum inhibitory effect is observed when the channel is open. SV188 inhibited the viability of MTC cell lines, MZ-CRC-1 and TT, with IC50 values of 8.47 μM and 9.32 μM, respectively, and significantly inhibited the invasion of MZ-CRC-1 cells by 35% and 52% at 3 μM and 6 μM, respectively. In contrast, SV188 had no effect on the invasion of TT cells derived from primary tumor, which have lower basal expression of NaV1.7. In addition, SV188 at 3 μM significantly inhibited the migration of MZ-CRC-1 and TT cells by 27% and 57%, respectively.

Adefovir Dipivoxil as a Therapeutic Candidate for Medullary Thyroid Carcinoma: Targeting RET and STAT3 Proto-Oncogenes

Aberrant gene expression is often linked to the progression of various cancers, making the targeting of oncogene transcriptional activation a potential strategy to control tumor growth and development. The RET proto-oncogene’s gain-of-function mutation is a major cause of medullary thyroid carcinoma (MTC), which is part of multiple endocrine neoplasia type 2 (MEN2) syndrome. In this study, we used a cell-based bioluminescence reporter system driven by the RET promoter to screen for small molecules that potentially suppress the RET gene transcription. We identified adefovir dipivoxil as a transcriptional inhibitor of the RET gene, which suppressed endogenous RET protein expression in MTC TT cells. Adefovir dipivoxil also interfered with STAT3 phosphorylation and showed high affinity to bind to STAT3. Additionally, it inhibited RET-dependent TT cell proliferation and increased apoptosis. These results demonstrate the potential of cell-based screening assays in identifying transcriptional inhibitors for other oncogenes.

Metastatic Neuroendocrine Tumors to Parotid Gland: Where Do They Come From?

Background. Metastasis to parotid gland occurs mostly from skin cancers of the head and neck region. Metastatic neuroendocrine tumors to the parotid gland are rare and not well studied so far. In this study, we undertook a retrospective review of secondary neuroendocrine tumors of the parotid diagnosed in our institution. The most common entities, primary tumor locations, their clinical presentations and histopathological features were analyzed. Methods. Cases of secondary neuroendocrine tumors to parotid diagnosed from August 1995 to Jan 2021 were retrieved from our institution's pathology databases, and their clinicopathological features were reviewed. Results. About 29% (120 of 420 cases) of parotid neoplasms were malignant, including 70 cases of parotid primary malignant tumors and 50 cases of metastases to parotid glands. Among metastatic tumors to the parotid glands, squamous cell carcinoma and melanoma of the head and neck region together accounted for about 78% of the cases. Only 11 of 50 metastatic tumors to the parotid were neuroendocrine carcinomas (22%). The most common primaries were poorly differentiated neuroendocrine carcinoma of lung (5 of 11 cases), including 4 cases of small cell carcinoma and one case of large cell neuroendocrine carcinoma. The second most common secondary tumor was Merkel cell carcinoma (4 of 11 cases, 36%) including one case of direct invasion from overlying skin. Medullary carcinoma of the thyroid comprised the rest of the metastases to the parotid (2 of 11 cases, 18%). Conclusion. Our results show that metastatic neuroendocrine carcinomas to the parotid gland account for about 22% of all metastatic tumors to the organ. Lung is the most common primary neuroendocrine carcinoma location. It is not uncommon for metastatic neuroendocrine carcinoma to present as the first sign of systemic clinical manifestation. Merkel cell carcinoma is the second most common entity that metastasizes to parotid, followed by medullary carcinoma of the thyroid.

Guideline Adherence and Practice Patterns in the Management of Medullary Thyroid Cancer

INTRODUCTION

Little is known about nationwide practice patterns for the management medullary thyroid cancer (MTC) in relation to the 2015 American Thyroid Association guidelines and their impact on survival.

METHODS

Using the Surveillance, Epidemiology, and End Results Program database (2000-2018), MTC treatment patterns were evaluated in terms of adherence to the 2015 American Thyroid Association guidelines across three time periods (2000-2009, 2010-2015, and 2016-2018). Outcomes of interest were guideline concordance, treatment utilization trends, disease-specific survival (DSS), and overall survival (OS).

RESULTS

A total of 3332 patients with MTC were identified. Of which, 53.8%, 33.2%, and 11.4% of patients had localized, regional, and distant disease, respectively. In patients with locoregional disease, the rate of guideline-concordant surgery improved over time from 63.0% in 2000-2009 to 76.0% in 2016-2018 (P < 0.001). Guideline-concordant care was associated with increased OS (HR = 1.85, 95% CI: 1.42-2.43, P < 0.001) in patients with localized disease and increased DSS (HR = 1.65, 95% CI: 1.01-2.54, P < 0.001) and OS (HR = 1.89, 95% CI: 1.35-2.58, P < 0.001) in patients with regional disease. The median OS and DSS in patients with distant disease were 31 and 55 mo, respectively, and the rate of chemotherapy use rose from 21.6% to 39.2% (P = 0.003).

CONCLUSIONS

The rate of guideline-concordant surgery for locoregional MTC increased after guideline publication in 2015, with an observed prolongment in OS and DSS. Chemotherapy use among patients with distant disease has increased over time, but their prognosis remains variable.

A Novel Germline Deletion of p.C630 in RET Causes MTC and Promotes Cell Proliferation and Sensitivity to Pralsetinib

CONTEXT

Medullary thyroid cancer (MTC) is usually caused by gain-of-function mutations in the proto-oncogene RET.

OBJECTIVE

This study aimed to determine the underlying mechanism in a male patient diagnosed with MTC at age 51 years.

METHODS

Genomic DNA extracted from leukocytes or tumor tissues of patients was used for next-generation sequencing (NGS)-panel sequencing and Sanger sequencing. Wild-type (WT) and p.C630 deletion RET were expressed in HEK 293T cells. Activation of phosphorylation of the crucial tyrosine-905 of RET and MAPK/ERK was analyzed by Western blotting. The effect of RET mutants on cell viability and colony formation ability was determined by CCK8 assay and a colony forming assay.

RESULTS

NGS-Panel sequencing revealed a 3-nucleotide/1-amino acid C630 in-frame deletion in exon 11 of RET (c.1887_1889delGTG p.C630del). In vitro expression showed that phosphorylation of the crucial tyrosine 905 was much stronger in the p.C630del RET mutant than in WT RET, indicating ligand-independent activation of the Ret protein tyrosine kinase. Furthermore, p.C630del RET mutant induced strong activation of the MAPK/ERK pathway. In addition, p.C630del RET mutant cells exhibited increased HEK 293T cell viability and colony formation compared with WT RET cells. Pralsetinib (BLU-667), a highly selective RET inhibitor, inhibited the viability of WT RET and p.C630del RET mutant-transfected HEK 293T cells (IC50s: 18.54 and 16.49 µM after treatment for 24 hours), followed by inhibition of the RET-induced MAPK/ERK pathway.

CONCLUSION

The finding in our patient with MTC was a 3-base-pair deletion in exon 11 of RET, a p.C630 deletion not previously reported. The p.C630del RET stimulates cell proliferation by increasing ligand-independent phosphorylation and activation of MAPK/ERK pathway, demonstrating the pathogenic nature of the mutation. We therefore recommend screening panel sequence of RET in MTC patients with indications of a genetic cause.

Molecular basis and targeted therapies for radioiodine refractory thyroid cancer

Patients diagnosed with radioiodine refractory thyroid cancer (RAIR-TC) are not amenable to novel ¹³¹ I therapy due to the reduced expression of sodium iodide symporter (Na+/I- symporter, NIS) and/or the impairment of NIS trafficking to the plasma membrane. RAIR-TC patients have a relatively poor prognosis with a mean life expectancy of 3-5 years, contributing to the majority of TC-associated mortality. Identifying RAIR-TC patients and selecting proper treatment strategies remain challenging for clinicians. In this review, we demonstrate the updated clinical scenarios or the so-called "definitions" of RAIR-TC suggested by several associations based on ¹³¹ I uptake ability and tumor response post-¹³¹ I therapy. We also discuss current knowledge of the molecular alterations involved in membrane-localized NIS loss, which provides a preclinical basis for the development of targeted therapies, in particular, tyrosine kinase inhibitors (TKIs), redifferentiation approaches, and immune checkpoint inhibitors.

Discovery of Pharmaceutical Composition for Prevention and Treatment in Patient-Derived Metastatic Medullary Thyroid Carcinoma Model

Medullary thyroid carcinoma (MTC) is a well-known neuroendocrine carcinoma, derived from C cells of the thyroid gland. Additionally, MTC is an uncommon aggressive carcinoma that metastasizes to lymph nodes, bones, lungs and liver. For MTC, the 10-year general survival ratio of patients with localized disease is about 95%, whereas that of patients with local phase disorder is around 75%. Only 20% of patients with distant metastasis to lung at diagnosis survive 10 years, which is notably lower than survival for well-differentiated thyroid carcinoma (WDTC). The management of MTC with distant metastasis to lung could be re-surgery or chemotherapy. In this research, we planned to assess the in vitro and in vivo combinational anticancer effect of a novel combination of low-dose cisplatin and sorafenib in patient-derived MTC. The patient-derived MTC cell lines YUMC-M1, M2, and M3 were isolated and treated with a combination of cisplatin and sorafenib or either agent alone. Cisplatin and sorafenib acted in combination to forward tumor restraint compared with each agent administered alone at a low dose. Therefore, a combination of cisplatin and sorafenib could be a new therapeutic approach for MTC.

Medullary thyroid carcinoma: a narrative historical review

INTRODUCTION

Sporadic or hereditary medullary thyroid carcinoma (MTC) is an uncommon thyroid malignancy arising from calcitonin secreting parafollicular C cells. Interestingly, MTC and calcitonin were distinct entities that were discovered independently yet concurrently, and their association was unknown.

AREAS COVERED

This review aims to present a historical review of the evolution of our understanding of MTC and its tumor marker calcitonin to highlight the prominent individuals that influenced and shaped our knowledge of this uncommon thyroid cancer type up to the dawn of the 21^st century. An overview of all published reports of novel research and work summarizing important findings for MTC and calcitonin was carried out.

EXPERT OPINION

Surgery remains the cornerstone of treatment for localized MTC. However, several new treatment options are either available or in development for advanced or metastatic MTC, including several novel small molecules targeting oncogenic RET and peptide receptor radionuclide therapy, immunotherapy, radioimmunotherapy, and radiofrequency ablation. In the near future, these novel treatments hold promise for therapy of this very distinct thyroid cancer type.

First-in-Human Experience With 177Lu-DOTAGA.(SA.FAPi)2 Therapy in an Uncommon Case of Aggressive Medullary Thyroid Carcinoma Clinically Mimicking as Anaplastic Thyroid Cancer

ABSTRACT

A 56-year-old man was diagnosed with calcitonin negative, plasma chromogranin A-positive, immunohistochemistry-negative, high-grade MTC (medullary thyroid cancer) behaving clinically like anaplastic thyroid cancer and presented with progressive disease after conventional therapies. A theranostic approach of 68Ga-DOTA.SA.FAPi-guided 177Lu-DOTAGA.(SA.FAPi)2 radionuclide therapy was administered on compassionate grounds as per the Declaration of Helsinki because known standard lines of treatment were ineffective. Treatment with a single cycle of 1.65 GBq 177Lu-DOTAGA.(SA.FAPi)2 demonstrated a sustainable reduction in the neck mass with significant improvement in the quality of life of the patient. 177Lu-DOTAGA.(SA.FAPi)2 is a potential theranostic option for high-grade MTC refractory to standard therapeutic options.

Metastatic medullary thyroid carcinoma: a new way forward

Medullary thyroid carcinoma (MTC) is a rare malignancy comprising 1-2% of all thyroid cancers in the United States. Approximately 20% of cases are familial, secondary to a germline RET mutation, while the remaining 80% are sporadic and also harbour a somatic RET mutation in more than half of all cases. Up to 15-20% of patients will present with distant metastatic disease, and retrospective series report a 10-year survival of 10-40% from time of first metastasis. Historically, systemic therapies for metastatic MTC have been limited, and cytotoxic chemotherapy has demonstrated poor objective response rates. However, in the last decade, targeted therapies, particularly multitargeted tyrosine kinase inhibitors (TKIs), have demonstrated prolonged progression-free survival in advanced and progressive MTC. Both cabozantinib and vandetanib have been approved as first-line treatment options in many countries; nevertheless, their use is limited by high toxicity rates and dose reductions are often necessary. New generation TKIs, such as selpercatinib or pralsetinib, that exhibit selective activity against RET, have recently been approved as a second-line treatment option, and they exhibit a more favourable side-effect profile. Peptide receptor radionuclide therapy or immune checkpoint inhibitors may also constitute potential therapeutic options in specific clinical settings. In this review, we aim to present all current therapeutic options available for patients with progressive MTC, as well as new or as yet experimental treatments.

A patent review on efficient strategies for the total synthesis of pazopanib, regorafenib and lenvatinib as novel anti-angiogenesis receptor tyrosine kinase inhibitors for cancer therapy

Angiogenesis is an important and interesting scientific subject in the area of malignant tumours. Current research importance and interest are directed in connection to blood microvessels in cancer cell proliferation, tumour growth, and metastasis. Tyrosine kinases have been intensely implicated as therapeutic targets that affect the angiogenic process in tumour growth. In the last decades, targeting angiogenesis has led to achievements in the therapy of different carcinomas by different mechanisms, such as the utilization of anti-angiogenic small molecule receptor tyrosine kinase inhibitors. In the current review, we aim to track the advancements in the total synthesis of three receptor tyrosine kinase inhibitors (pazopanib, regorafenib and lenvatinib). This review surveys different synthetic routes for these three approved drugs (pazopanib, regorafenib and lenvatinib) which were previously published as patents (2014-2021). The purity of medicines is a very important factor during manufacturing so we have decided to review the purification process of these anticancer medicines as well. It should be noted that the different patents may have reported some procedures with different yields and purities for the synthesis of desired drug and their intermediates. In order to simplify the understanding of the contents of this review article, only the best results reported in each of these patents are reported for the synthesis of desired drug and their intermediates.

Multiple endocrine neoplasia 2: an overview

This review article discusses the diagnosis and treatment of patients with multiple endocrine neoplasia type 2 (MEN2). The most common tumors associated with MEN2 are those of the parathyroid, thyroid, and adrenal glands. Additional manifestations include characteristic clinical phenotypes or features as described in the article. This review provides an overview of clinical manifestations, screening, diagnosis, treatment, and surveillance of patients with MEN2.

Encapsulated papillary variant of medullary carcinoma of thyroid with extensive cystic change: an extremely rare presentation

Papillary variant of medullary carcinoma of the thyroid is an unusual subtype with many diagnostic challenges. The authors report a case of papillary variant of thyroid medullary carcinoma in a 37-year-old female, who presented with complaints of pain in the thyroid nodule for the latter two months. Contrast enhanced computed tomography (CECT) neck revealed an enlarged and heterogeneously enhancing left lobe of thyroid. This was followed by hemithyroidectomy for suspicion of colloid goitre. Gross examination of the cut surface of the thyroid parenchyma had a sponge like appearance. On histopathology a diagnosis of encapsulated papillary variant of medullary carcinoma thyroid was made with the help of special stains and immunohistochemistry (IHC).

Opportunities and Challenges of Liquid Biopsy in Thyroid Cancer

Thyroid cancer is the most common malignancy of the endocrine system, encompassing different entities with distinct histological features and clinical behavior. The diagnostic definition, therapeutic approach, and follow-up of thyroid cancers display some controversial aspects that represent unmet medical needs. Liquid biopsy is a non-invasive approach that detects and analyzes biological samples released from the tumor into the bloodstream. With the use of different technologies, tumor cells, free nucleic acids, and extracellular vesicles can be retrieved in the serum of cancer patients and valuable molecular information can be obtained. Recently, a growing body of evidence is accumulating concerning the use of liquid biopsy in thyroid cancer, as it can be exploited to define a patient's diagnosis, estimate their prognosis, and monitor tumor recurrence or treatment response. Indeed, liquid biopsy can be a valuable tool to overcome the limits of conventional management of thyroid malignancies. In this review, we summarize currently available data about liquid biopsy in differentiated, poorly differentiated/anaplastic, and medullary thyroid cancer, focusing on circulating tumor cells, circulating free nucleic acids, and extracellular vesicles.

Selective Antitumor Activity of Datelliptium toward Medullary Thyroid Carcinoma by Downregulating RET Transcriptional Activity

Simple Summary

Medullary thyroid carcinoma (MTC) is a rare aggressive type of thyroid cancer with a propensity for metastasizing to the lymph nodes, liver, bones, and lungs. Previous studies have demonstrated that activated REarranged during Transfection (RET) mutants are key regulators of invasive and metastatic behaviors in MTC. The present study aimed to evaluate the antiinvasive and antimetastatic potential of a novel RET transcription inhibitor, datelliptium, which stabilizes the RET G-quadruplex structures and suppresses RET oncogene transcription by examining its effects on epithelial-to-mesenchymal transition (EMT), cancer stem cells (CSCs), and MTC cell migration. Interestingly, the ablation of RET with datelliptium resulted in decreased EMT, spheroid formation, and MTC cell migration. In this study, we also demonstrated the in vivo antitumor activity in TT tumor-bearing mice with about 75% tumor growth inhibition.

Abstract

Medullary thyroid carcinoma (MTC) is a rare aggressive form of thyroid cancer with high rates of metastasis. Sporadic and hereditary MTC are strongly driven by somatic and germline mutations, respectively, in the transmembrane REarranged during Transfection (RET) proto-oncogene, which encodes a receptor tyrosine kinase. Our previous study identified datelliptium as a novel RET transcription inhibitor, which stabilizes the RET G-quadruplex structures and suppresses RET oncogene transcription. The present study aimed to elucidate the effect of datelliptium on the suppression of epithelial-to-mesenchymal transition (EMT) and metastasis-related behaviors of MTC cells, including cell migration and formation of cancer stem cells (CSCs). Our results demonstrated that datelliptium downregulated the expression of the mesenchymal markers, including N-cadherin, vimentin, slug, snail, and claudin-1. Compared to untreated cells, datelliptium significantly decreased the migration of TT cells in a dose-dependent manner in a wound healing assay. Additionally, datelliptium significantly reduced the size of preformed spheroids from TT cells over the time course. Finally, datelliptium inhibited approximately 75% of MTC xenograft growth with minimal systemic toxicity. In conclusion, datelliptium exerts its antitumor activity against MTC cells by reducing the EMT program, migratory ability, and self-renewal capacity of TT cells, thus preventing invasive and metastatic behavior of MTC.

Vandetanib versus Cabozantinib in Medullary Thyroid Carcinoma: A Focus on Anti-Angiogenic Effects in Zebrafish Model

Medullary thyroid carcinoma (MTC) is a tumor deriving from the thyroid C cells. Vandetanib (VAN) and cabozantinib (CAB) are two tyrosine kinase inhibitors targeting REarranged during Transfection (RET) and other kinase receptors and are approved for the treatment of advanced MTC. We aim to compare the in vitro and in vivo anti-tumor activity of VAN and CAB in MTC. The effects of VAN and CAB on viability, cell cycle, and apoptosis of TT and MZ-CRC-1 cells are evaluated in vitro using an MTT assay, DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, respectively. In vivo, the anti-angiogenic potential of VAN and CAB is evaluated in Tg(fli1a:EGFP)^y1 transgenic fluorescent zebrafish embryos by analyzing the effects on the physiological development of the sub-intestinal vein plexus and the tumor-induced angiogenesis after TT and MZ-CRC-1 xenotransplantation. VAN and CAB exert comparable effects on TT and MZ-CRC-1 viability inhibition and cell cycle perturbation, and stimulated apoptosis with a prominent effect by VAN in MZ-CRC-1 and CAB in TT cells. Regarding zebrafish, both drugs inhibit angiogenesis in a dose-dependent manner, in particular CAB shows a more potent anti-angiogenic activity than VAN. To conclude, although VAN and CAB show comparable antiproliferative effects in MTC, the anti-angiogenic activity of CAB appears to be more relevant.

Long-term follow-up and safety of vandetanib for advanced medullary thyroid cancer

INTRODUCTION

Vandetanib is indicated for adults with advanced medullary thyroid cancer (MTC).

OBJECTIVES

To describe the efficacy and toxicity profile of vandetanib treatment with a maximal follow-up of 11 years at Institut Gustave Roussy/France.

METHODS

A review of the clinical files of the 76 MTC patients treated with vandetanib. Efficacy was estimated by markers and imaging.

RESULTS

A total of 76 patients received vandetanib. Nine were excluded from efficacy analysis because lack of morphological data. The overall (N = 76) median treatment duration was 17.6 (range: 0.7-130.6) months and the median progression-free survival (PFS) was 22.7 (95% CI, 13.9-37.3) months. In total, 21/76 (27.6%) patients were classified as long-term users because have received vandetanib for more than 48 months, with a median treatment duration of 68.1 (range: 49.1-130.6) months. For long-term vandetanib users, the objective response rate was 85.7%, the median time to best response was 27.8 (11.6.1-110) months and the median duration of response was 70.4 (38.3-127.5) (95% CI 49.5-102.8) months with a median PFS of 73.2 (95% CI, 53.1-105.6) months. Duration of response had a significant negative correlation with patient age at diagnosis (p = 0.03) and was significantly higher in patients that did not have confirmed tumor progression before treatment onset (p = 0.007). After 48 months of vandetanib use, renal failure took place in two patients and heart failure, cholecystitis, acute pancreatitis, posterior encephalopathy, and skin cancer first occurred in one patient, each.

CONCLUSIONS

Our findings suggest that a substantial number of patients receiving first-/second-line vandetanib may sustain long clinical benefit and that a younger age at diagnosis and the absence of progression before treatment could be considered as predictors of durable response.

Role of tissue and circulating microRNAs and DNA as biomarkers in medullary thyroid cancer

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor comprising hereditary or sporadic form with frequent mutations in the rearranged during transfection (RET) or RAS genes. Diagnosis is based on the presence of thyroid tumor mass with altered levels of calcitonin (Ctn) and carcinoembryonal antigen (CEA) in the serum and/or in the cytological smears from fine needle aspiration biopsies. Treatment consists of total thyroidectomy, followed by tyrosine kinase inhibitors (TKi) in case of disease persistence. During TKi treatment, Ctn and CEA levels can fluctuate regardless of tumor volume, metastasis or response to therapy. Research for more reliable non-invasive biomarkers in MTC is still underway. In this context, circulating nucleic acids, namely circulating microRNAs (miRNAs) and cell free DNA (cfDNA), have been evaluated by different research groups. Aiming to shed light on whether miRNAs and cfDNA are suitable as MTC biomarkers we searched three different databases, PubMed, Scopus, WOS and reviewed the literature. We classified 83 publications fulfilling our search criteria and summarized the results. We report data on miRNAs and cfDNA that can be evaluated for validation in independent studies and clinical application.

[The role of molecular testing in thyroid tumors]

&sup1;I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; &sup2;Endocrinology Research Centre, Moscow, Russia Thyroid cancer is the most common endocrine gland cancer. In the last few decades, the molecular diagnostics for thyroid tumors have been widely researched. It is one of the few cancers whose incidence has increased in recent years from microcarcinomas to common, large forms, in all age groups, from children to the elder people. Most researches focus on the genetic basis, since our current knowledge of the genetic background of various forms of thyroid cancer is far from being complete. Molecular and genetic research has several main directions: firstly, differential diagnosis of thyroid tumors, secondly, the prognostic value of detected mutations in thyroid cancer, and thirdly, targeted therapy for aggressive or radioactive iodine-resistant forms of thyroid cancer. In this review, we wanted to update our understanding and describe the prevailing advances in molecular genetics of thyroid cancer, focusing on the main genes associated with the pathology and their potential application in clinical practice.

Molecular Diagnosis and Treatment of Multiple Endocrine Neoplasia Type 2B in Ethnic Han Chinese

BACKGROUND

Multiple endocrine neoplasia type 2B (MEN 2B) is mainly caused by M918T RET germline mutation, and characterized by medullary thyroid carcinoma (MTC), pheochromocytoma (PHEO) and non-endocrine features. However, the diagnosis and treatment are usually delayed.

METHODS

This study reports 5 Chinese pedigrees with 5 individuals harboring germline RETM918T, and systematically reviewed previous Chinese literature reported.

RESULTS

All 5 patients initially presented MTC, but none had biochemically cured postoperatively. 2 also presented bilateral PHEO after adrenal-sparing surgery, 1 needed steroid replacement. Further, a total of 32 MEN 2B patients from literature were clustered with 28 available for analysis. 26 (92.8%) were diagnosed by endocrine-related symptoms; the remaining 2 (7.2%) due to RET testing and oral symptoms, respectively. 25 patients underwent thyroidectomy with/without neck lymph node dissection at the mean age of (23.3 ± 10.4) years. Histopathological examination revealed MTC (100%). Of them, 17 had definite TNM stage, with 1 in stage III and others in IV. Other information of MEN 2B-related symptoms included penetrance of PHEO (60.7%), constipation (32.1%), Hirschsprung disease (25%), alacrima (17.8%), mucosal ganglioneuroma (96.4%) and marfanoid habitus (71.4%). 19 patients were verified harboring RET-M918T (c.2753T>C), of whom 15 (78.9%) were de novo mutation. The other 9 were clinically diagnosed as MEN 2B.

DISCUSSION & CONCLUSION

The initial diagnosis of MEN 2B is relatively later, and diagnosed by non-endocrine components is extremely lower. Recognition of MEN 2B and its non-endocrine-related components is still the utmost requirement for a Chinese physician. Combined RET screening and serum calcitonin detection can facilitate early diagnosis.

The Benefit of Primary Tumor Surgical Resection in Distant Metastatic Carcinomas of the Thyroid

OBJECTIVES/HYPOTHESIS

Thyroid cancer with distant metastasis (TCDM) at diagnosis has significantly worse survival rates when compared to localized/regional thyroid cancer. This study sought to report on the characteristics of patients presenting with TCDM and the potential survival advantage of surgical resection.

STUDY DESIGN

Data were acquired from the Surveillance, Epidemiology, and End Results (SEER) database with cases from 2004 to 2015.

METHODS

TCDM cases (n = 2,558) were identified from the SEER database. The Bonferroni correction was applied for multivariate analysis. Kaplan-Meier analysis was utilized to obtain disease-specific survival (DSS) rates. Cox regression analysis was utilized to identify independent factors significantly associated with survival.

RESULTS

The average age of diagnosis of TCDM was 62.0 (±17.5) years. Patients were predominantly white (74.6%), female (54.6%), in a relationship (56.0%), and between ages 36 and 80 years (76.4%). Cases consisted of papillary (57.2%), follicular (16.0%), medullary (8.9%), anaplastic (17.9%) TCDM histological variants. Overall 1-, 5-, and 10-year DSS rates were 72.0%, 56.8%, and 43.8%, respectively. Anaplastic and medullary variants had the worst 10-year DSS (0% and 25.5%, respectively). Patients who underwent surgical resection only and surgical resection with radiation were 49% and 59% less likely to die, respectively. Treatment, age, histology, T staging, relationship status, and metastasis site were determined to be significant predictors of survival.

CONCLUSIONS

Surgical resection with radiation was found to be a significant predictor of survival after applying the Bonferroni correction for all thyroid cancer variants except medullary. To increase survival, surgical intervention should be recommended in patients who are deemed to be medically tolerant of surgery.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1026-1034, 2021.

MET receptor in oncology: From biomarker to therapeutic target

First discovered in the 1984, the MET receptor tyrosine kinase (RTK) and its ligand hepatocyte growth factor or HGF (also known as scatter factor or SF) are implicated as key players in tumor cell migration, proliferation, and invasion in a variety of cancers. This pathway also plays a key role during embryogenesis in the development of muscular and nervous structures. High expression of the MET receptor has been shown to correlate with poor prognosis and resistance to therapy. MET exon 14 splicing variants, initially identified by us in lung cancer, is actionable through various tyrosine kinase inhibitors (TKIs). For this reason, this pathway is of interest as a therapeutic target. In this chapter we will be discussing the history of MET, the genetics of this RTK, and give some background on the receptor biology. Furthermore, we will discuss directed therapeutics, mechanisms of resistance, and the future of MET as a therapeutic target.

Management of treatment-related toxicities in advanced medullary thyroid cancer

PURPOSE OF REVIEW

Tyrosine kinase inhibitors (TKI), predominantly vandetanib and cabozantinib, are increasingly used for management of advanced medullary thyroid cancer. This review aims to discuss the major and serious adverse events associated with TKI.

RECENT FINDINGS

The choice of TKI depends on the patient's existing comorbidities. Patients who have long QT interval should avoid vandetanib and those at risk of gastrointestinal perforation should avoid cabozantinib. Hypertension is common during the first 3 months. Treatments include ACE inhibitors, calcium channel blockers (avoiding verapamil and diltiazem, which are CYP3A4 inhibitors), and beta blockers. Diuretics should be second line because of derangement of electrolytes, which may exacerbate QT interval. As nitric oxide (NO) blockade and ET1 are implicated in the mechanism of hypertension, nitrates and endothelin receptor antagonists may be used. Thromboembolism may require anticoagulation or revascularization procedures. Prolonged QT interval should be treated by dose interruption and reduction, correction of electrolytes, and avoidance of medications, which prolong QTc interval. Diarrhoea is managed symptomatically and with electrolyte replacement, dermatological adverse events with avoidance of exacerbating factors and topical therapies. Thyroid function should be monitored.

SUMMARY

Toxicities are common with TKI use, and management involves symptomatic treatment, avoidance of triggers, dose interruption, and dose reduction.

Salinomycin and its derivatives as potent RET transcriptional inhibitors for the treatment of medullary thyroid carcinoma

Rearranged during transfection kinase (RET) is a validated molecular target in medullary thyroid cancer (MTC), as activating mutations in RET are often associated with the development of MTC. The present study reports the first preclinical characterization of salinomycin and selected analogs as potent RET transcriptional inhibitors. Reverse transcription‑PCR and immunoblotting revealed that salinomycin profoundly decreased RET expression in the TT human MTC cell line by inhibiting RET transcription. Moreover, salinomycin resulted in remarkable anti‑proliferative activity against MTC that is driven by RET (gain of function mutation) by selectively inhibiting the intracellular PI3K/Akt/mTOR signaling pathway. Also, flow cytometry and fluorescence‑activated cell sorting showed that salinomycin induces G1 phase arrest and apoptosis by reducing the expression of retinoblastoma protein, E2F1, cyclin D and CDK4. The structure‑activity relationship of salinomycin was investigated in this study. Some of the salinomycin derivatives showed the ability to reduce RET expression where others fail to alter RET expression. These results suggest that the RET‑suppressing effect of salinomycin may be largely attributed to disruption of the Wnt pathway, presumably through interference with the ternary LRP6‑Frizzled‑Wnt complex. Furthermore, these findings support the further preclinical evaluation of salinomycin and its analogs as a promising new class of therapeutic agents for the improved treatment of MTC.

Molecular Alterations in Thyroid Cancer: From Bench to Clinical Practice

Thyroid cancer comprises different clinical and histological entities. Whereas differentiated (DTCs) malignancies are sensitive to radioiodine therapy, anaplastic (ATCs) and medullary (MTCs) tumors do not uptake radioactive iodine and display aggressive features associated with a poor prognosis. Moreover, in a majority of DTCs, disease evolution leads to the progressive loss of iodine sensitivity. Hence, iodine-refractory DTCs, along with ATCs and MTCs, require alternative treatments reflective of their different tumor biology. In the last decade, the molecular mechanisms promoting thyroid cancer development and progression have been extensively studied. This has led to a better understanding of the genomic landscape, displayed by thyroid malignancies, and to the identification of novel therapeutic targets. Indeed, several pharmacological compounds have been developed for iodine-refractory tumors, with four multi-target tyrosine kinase inhibitors already available for DTCs (sorafenib and lenvatinib) and MTCs (cabozantib and vandetanib), and a plethora of drugs currently being evaluated in clinical trials. In this review, we will describe the genomic alterations and biological processes intertwined with thyroid cancer development, also providing a thorough overview of targeted drugs already tested or under investigation for these tumors. Furthermore, given the existing preclinical evidence, we will briefly discuss the potential role of immunotherapy as an additional therapeutic strategy for the treatment of thyroid cancer.

Recent advances on anti-angiogenesis receptor tyrosine kinase inhibitors in cancer therapy

Angiogenesis has always been the topic of major scientific interest in the field of malignant tumors. Nowadays, targeting angiogenesis has achieved success in various carcinomas by several mechanisms, including the use of anti-angiogenic small molecule receptor tyrosine kinase inhibitors (TKIs). The development of TKIs targeting pro-angiogenic receptors, mainly vascular endothelial growth factor receptor (VEGFR) family, have significantly improved the outcome of certain types of cancers, like renal cell carcinoma, hepatocellular carcinoma, and colorectal carcinoma. However, the general response rate is not very satisfactory. The particular toxicity profile and resistance to anti-angiogenic targeted agents are unavoidable, and no specific marker is available to screen responsive patients to TKIs for precision therapy. To date, about 11 anti-angiogenic TKIs with different binding capacities to angiogenic receptor tyrosine kinase have been approved for the treatment of patients with advanced cancers. This review presents all approved anti-angiogenic small molecule receptor TKIs so far with an emphasis on their indications and clinical efficacy. We also discuss the combination between TKIs and immune checkpoint blockade inhibitors based on the most recent exciting outcome in immunotherapy.

Novel Prognostic Factors Associated with Cell Cycle Control in Sporadic Medullary Thyroid Cancer Patients

BACKGROUND

Medullary thyroid cancer (MTC) is a rare neuroendocrine-derived malignancy. It is represented by sporadic and familiar forms, and both can have RET oncogene mutations. Numerous markers can be used to define MTC; however, none is generally approved for predicting the outcome of sporadic MTC.

AIM

The aim of this work was to analyze PTTG1/securin and Aurora kinase A expressions in MTC patients, both at the gene and protein levels, and to define their prognostic role in MTC assessing their association with lab and clinical parameters.

PATIENTS AND METHODS

Seventy-one sporadic MTC human samples were analyzed for RET mutations and by qPCR for PTTG1 and AURKA (Aurora kinase A) expression. Ki-67 levels and western blot reactivity for PTTG1 and Aurora kinase A were also determined in a selected cohort of patients.

RESULTS

RET somatic mutations were found in 48% of the patients (34/71). PTTG1 expression was statistically different among the groups with or without regional lymph node metastasis (p < 0.0001) and advanced stage disease (p < 0.01). PTTG1 and AURKA expressions were statistically higher than those of controls (p = 0.01 and p < 0.002, respectively). PTTG1 expression and Ki-67 levels were statistically different among the groups with remitted or persistent disease (p < 0.05 and p < 0.01, respectively). We found a significant correlation between the expressions of AURKA and PTTG1 (p < 0.0002, r = 0.5298) and between the expressions of PTTG1 and Ki-67 (p = 0.01). Ki-67 levels were statistically different among the groups with or without metastatic lymph nodes (p = 0.01) or distant metastases (p = 0.003).

CONCLUSION

The presence of an altered expression of PTTG1 and AURKA is a negative prognostic factor associated with a more aggressive course of disease, such as an advanced stage or disease persistence. It emerges as a cell cycle process mediated by the 2 factors, in addition to the RET pathway, which can be altered in MTC patients.

Therapeutic options for advanced thyroid cancer

Thyroid cancer can be largely classified as well-differentiated, poorly differentiated, medullary and anaplastic. Differentiated thyroid cancer (DTC) includes follicular and papillary subtypes, with the incidence of papillary thyroid cancer (PTC) on the rise. The mainstay of treatment for DTC includes a combination of surgery, radioactive iodine (RAI) and levothyroxine suppression. DTC portends a favorable prognosis, even in the presence of distant metastases, with a 50% rate of 5-year survival largely due to tumor cell's sensitivity to RAI therapy influencing disease outcome. In radioactive iodine refractory differentiated thyroid cancer (RAI-refractory DTC) there is a lower survival rate prompting the use of other therapeutic options available. RAI refractoriness is more common in older patients (age >40), large metastases and lesions that are fluorodeoxyglucose (FDG) avid on position emission tomography (PET). Over the past decade, Identification of genetic mutations in the signaling pathway involved in thyroid tumorigenesis has led to the approval of tyrosine kinase inhibitors (TKIs); Sorafenib and Lenvatinib in RAI-refractory DTC. Similarly, metastatic medullary thyroid cancer (MTC) implies an unfavorable 10-year survival rate of only 20% as the principal treatment options focuses on loco regional control via surgical and/or non-surgical options. The approval of TKIs such as Cabozantinib and Vandetanib has introduced an encouraging, novel, systemic therapeutic option for metastatic MTC. Lastly, anaplastic thyroid cancer (ATC) carries the worst prognosis with high recurrence rates. Treatment includes surgery, chemotherapy and external beam radiation. The FDA recently approved Dabrafenib plus trametinib for BRAF V600E mutated ATC. Considering the modality of chemotherapy and the expanding field of targeted therapies, the role of the oncologist and interaction with endocrinologist in the management of thyroid cancer needs further clarification aiming at collaborative management plans more than ever. This review summarizes the key phase III trials that led to the approval of TKIs in the treatment of DTC and metastatic MTC. Additionally, the review aims to clarify the patient selection criteria for initiation of TKIs and examine the implications, considerations and adverse effects prior to utilizing targeted therapy. Clinical trials are ongoing with promising results and may contribute to the addition of several targeted molecules and immune check point inhibitors to the therapeutic armamentarium for RAI-refractory DTC, medullary and anaplastic thyroid cancer.

Pazopanib, Cabozantinib, and Vandetanib in the Treatment of Progressive Medullary Thyroid Cancer with a Special Focus on the Adverse Effects on Hypertension

Medullary thyroid cancer (MTC) is a rare malignancy with a poor prognosis. First line therapy is surgery, which is the only curative method of the disease. However, in non-operable cases or with tumor progression and metastases, a systemic treatment is necessary. This form of cancer is often insensitive to conventional chemotherapy, but the use of tyrosine kinase inhibitors (TKIs), such as pazopanib, cabozantinib, and vandetanib, has shown promising results with an increase in progression-free survival and prolonged lifetime. Therefore, we focused on the pharmacological characteristics of TKIs, their mechanism of action, their application as a secondary treatment option for MTC, their efficacy as a cancer drug treatment, and reviewed the ongoing clinical trials. TKIs also act systemically causing various adverse events (AEs). One common AE of this treatment is hypertension, known to be associated with cardiovascular disease and can therefore potentially worsen the well-being of the treated patients. The available treatment strategies of drug-induced hypertension were discussed. The mechanism behind the development of hypertension is still unclear. Therefore, the treatment of this AE remains symptomatic. Thus, future studies are necessary to investigate the link between tumor growth inhibition and hypertension. In addition, optimized, individual treatment strategies should be implemented.

ERBB1- and ERBB2-Positive Medullary Thyroid Carcinoma: A Case Report

Medullary thyroid carcinomas (MTCs) are rare thyroid tumors occurring in both sporadic and hereditary forms, whose pathogenesis is related to RET proto-oncogene alterations. MTCs originate from parafollicular cells, which produce calcitonin that represents the biochemical activity of MTC. Total thyroidectomy is the main treatment for MTC and often cures patients with confined diseases. In the presence of metastasis, the therapeutic approach depends on the rate of disease progression. We report a case of a 54-year-old female with a single, incidentally discovered, thyroid nodule of 1 cm, classified as suspicious MTC after a stimulation test with intravenous (iv) calcium. After surgery, we examined the nodule using immunohistochemistry, immunofluorescence, and electron microscopy. In addition to calcitonin, we found that it expressed intracellular positivity for the tyrosine kinase RTK receptors ERBB1 and ERBB2. Consistently with MTC features, the ultrastructural examination of the tumor displayed heterogeneous spindle-shaped cells containing two groups of secretory granules. Because of the significant correlation found between high ERBB1/ERBB2 levels in MTCs and extrathyroidal growth, the detection of ERBB1 and ERBB2 expression suggests that the two oncoproteins may be involved in the tumor proliferative responses and/or in the differentiation of parafollicular C-cells. The biological, prognostic, and therapeutic significance of these patterns would merit further investigations.