Update on medullary thyroid cancer

Theranostics of Thyroid Cancer

Molecular imaging is pivotal in evaluating and managing patients with different thyroid cancer histotypes. The existing, pathology-based, risk stratification systems can be usefully refined, by incorporating tumor-specific molecular and molecular imaging biomarkers with theranostic value, allowing patient-specific treatment decisions. Molecular imaging with different radioactive iodine isotopes (ie, I131, I123, I124) is a central component of differentiated carcinoma (DTC)'s risk stratification while [18F]F-fluorodeoxyglucose ([18F]FDG) PET/CT is interrogated about disease aggressiveness and presence of distant metastases. Moreover, it is particularly useful to assess and risk-stratify patients with radioiodine-refractory DTC, poorly differentiated, and anaplastic thyroid cancers. [18F]F-dihydroxyphenylalanine (6-[18F]FDOPA) PET/CT is the most specific and accurate molecular imaging procedure for patients with medullary thyroid cancer (MTC), a neuroendocrine tumor derived from thyroid C-cells. In addition, [18F]FDG PET/CT can be used in patients with more aggressive clinical or biochemical (ie, serum markers levels and kinetics) MTC phenotypes. In addition to conventional radioiodine therapy for DTC, new redifferentiation strategies are now available to restore uptake in radioiodine-refractory DTC. Moreover, peptide receptor theranostics showed promising results in patients with advanced and metastatic radioiodine-refractory DTC and MTC, respectively. The current appropriate role and future perspectives of molecular imaging and theranostics in thyroid cancer are discussed in our present review.

The Establishment and Verification of a Nomogram Model for Predicting the Overall Survival of Medullary Thyroid Carcinoma: An Analysis Based on the SEER Database

(1) Background: This study aimed to establish a nomogram model for predicting the overall survival (OS) of medullary thyroid carcinoma (MTC) patients based on the Surveillance, Epidemiology, and End Results (SEER) database. (2) Methods: Patients with MTC in the SEER database from 2004 to 2015 were included and divided into a modeling group and an internal validation group. We also selected MTC patients from our center from 2007 to 2019 to establish an external validation group. Univariate and multivariate Cox regression analyses were used to screen for significant independent variables and to establish a nomogram model. Kaplan-Meier (K-M) curves were plotted to evaluate the influence of the predictors. The C-indexes, areas under the curves (AUCs), and calibration curves were plotted to validate the predictive effect of the model. (3) Results: A total of 1981 MTC patients from the SEER database and 85 MTC patients from our center were included. The univariate and multivariate Cox regression analyses showed that age, tumor size, N stage, and M stage were significant factors, and a nomogram model was established. The C-index of the modeling group was 0.792, and the AUCs were 0.811, 0.825, and 0.824. The C-index of the internal validation group was 0.793, and the AUCs were 0.847, 0.846, and 0.796. The C-index of the external validation group was 0.871, and the AUCs were 0.911 and 0.827. The calibration curves indicated that the prediction ability was reliable. (4) Conclusions: A nomogram model based on age, tumor size, N stage, and M stage was able to predict the OS of MTC patients.

Lobectomy may be more appropriate for patients with early-stage medullary thyroid cancer older than 60 years old

PURPOSE

Clinical guidelines presently recommend total thyroidectomy for the treatment of medullary thyroid cancer (MTC). This study was aimed to investigate whether lobectomy could be the initial treatment for stage I MTC patients.

METHODS

The retrospective study was based on data from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. The risk factors of survival were estimated by the univariate and multivariate Cox proportional-hazards model. The effect of age on death risk was estimated using restricted cubic splines. Survival curves were constructed according to the Kaplan-Meier method.

RESULTS

A total of 988 stage I MTC patients was included in the study. Among them, 506 (51.2%) MTC patients received lobectomy and 482 (48.8%) received total thyroidectomy. The only independent prognostic factor for overall survival (OS) and disease-specific survival (DSS) was age, according to univariate and multivariate Cox regression analysis. The hazard ratio (HR) increased relatively slowly with age growing under the age of approximately 60 years. However, the death risk of MTC patients began to rise sharply with increasing age above 60 years. For patients under the age of 60, a significant survival difference for OS and DSS was observed between the lobectomy group and total thyroidectomy group (p < 0.05). However, for patients aged above 60, no significant survival difference was observed for OS or DSS (p > 0.05).

CONCLUSION

Total thyroidectomy was an appropriate treatment for stage I MTC patients under the age of 60, which was consistent with the recommendation of the clinical guidelines. However, for those over the age of 60, lobectomy may be explored as a better surgical option. The findings may provide the evidence base for improving the clinical management of stage I MTC patients. Further prospective multicenter clinical studies are needed including information regarding RET status as well as calcitonin and CEA levels.

Correlation of molecular data with histopathological and clinical features in a series of 66 patients with medullary thyroid carcinoma

PURPOSE

Medullary thyroid carcinoma (MTC) displays a wide variety of histopathological features, and several histological variants have been described. In follicular cell-derived thyroid carcinomas, there is a good correlation between genotype and phenotype. In this study, we investigated whether such a correlation is also present in MTC.

METHODS

The histopathological features were evaluated in a series of 66 molecularly characterised tumours and correlated with the clinical characteristics.

RESULTS

Most MTC exhibited the classical variant (83.3%). Other variants included spindle cell (6.1%), pseudopapillary (4.5%), paraganglioma-like (3.0%), angiosarcoma-like (1.5%), and oncocytic follicular (1.5%). Tumours were classified into four groups: group 1, with somatic p.Met918Thr and p.Ala883Phe RET mutations; group 2, with other RET mutations; group 3, with RAS mutations; and group 4, without RET or RAS mutations. Tumours from groups 1 and 4 were typically associated with the classical variant, with abundant fibrosis, lymphovascular invasion, extrathyroidal extension, and more advanced stages of disease, whereas group 2 included histological variants other than the classical variant (namely, pseudopapillary and paraganglioma-like), with tumours that were highly cellular, less invasive, and with a better overall prognosis. In tumours from group 4, amyloid deposition was characteristically absent or low. The spindle cell variant appeared only in tumours from group 3, which had high cellularity and a degree of invasion and prognosis intermediate between groups 1 and 2, but better than group 4. The grade of fibrosis correlated directly with the clinical outcome.

CONCLUSION

Our results support the idea that a genotype-phenotype correlation does, indeed, exist in MTC. However, further studies are warranted to confirm these findings in a larger sample size.

Medullary thyroid cancer: molecular factors, management and treatment

Medullary thyroid cancer (MTC) is an infrequent neuroendocrine tumor, which amounts to 3–5% of all thyroid malignancies. Approximately 75–80% of MTCs are sporadic neoplasms. The rest of 20–25% are familial cases that belong to multiple endocrine neoplasia (MEN) syndromes, specifically MEN2 and MEN3. These cases of familial MTC are attributed to an activating germline mutation of a tyrosine kinase receptor gene, the rearranged during transfection (RET) proto-oncogene, located on chromosome 10q11.21. These mutations are also found in some cases of sporadic MTC. This review sets forth in summary the accepted guidelines and approaches regarding diagnosis, management, and treatment of MTC. Surgical resection is the standard care, and an early, prophylactic intervention is performed in genetic cases. Further investigation and understanding of the molecular pathways involved in the growth and advancement of MTC is required in order to provide efficient therapy in cases of progressive disease.

The role of tumour biomarkers in choosing the appropriate positron emission tomography imaging in follow-up of medullary thyroid cancer

INTRODUCTION

We aimed to demonstrate the importance of serum calcitonin (Ct) and carcinoembryonic-antigen (CEA) levels in the selection of appropriate positron emission tomography/computed tomography (PET/CT) modality in the follow-up of operated patients with medullary thyroid cancer.

METHODS

Fourteen operated patients (8 Female, 6 Male) with MTC underwent PET/CT imaging with somatostatin (⁶⁸ Ga-DOTATATE) and glucose (¹⁸ FDG) analogs due to elevated Ct or CEA at follow-up. Ct and CEA levels and both PET/CT findings were compared based on both patients and lesions.

RESULTS

Positive findings were found in 10 patients with ⁶⁸ Ga-DOTATATE-PET/CT and in 8 patients with ¹⁸ FDG-PET/CT, and sensitivity was found as 71.4% and 57.1% for both imaging methods, respectively (P > 0.05). Lesion could be detected with ⁶⁸ Ga-DOTATATE-PET/CT in 3 patients in whom lesion could not be detected with ¹⁸ FDG-PET/CT. In one patient, whereas no pathological lesion was with ⁶⁸ Ga-DOTATATE-PET/CT, lesion could be detected with ¹⁸ FDG-PET/CT in this patient. Of the total 67 lesions, 62 could be shown with ⁶⁸ Ga-DOTATATE-PET/CT, while 48 lesions could be detected with ¹⁸ FDG-PET/CT (P < 0.05). A statistically significant positive correlation was found between Ct level and the number of lesions detected on the ⁶⁸ Ga-DOTATATE-PET/CT, and similarly between CEA level and the number of lesions detected on the ¹⁸ FDG-PET/CT.

CONCLUSIONS

It was found that ⁶⁸ Ga-DOTATATE-PET/CT is superior over ¹⁸ FDG-PET/CT method in detection of recurrent disease in the follow-up of MTC, and serum Ct and CEA levels are important biomarkers in the selection of appropriate PET/CT modality.

Anlotinib for the Treatment of Patients with Locally Advanced or Metastatic Medullary Thyroid Cancer

BACKGROUND

The prognosis of advanced or metastatic medullary thyroid carcinoma (MTC) is poor, and there are few therapeutic options. Anlotinib has previously shown promising antitumor activity on MTC in preclinical models and a Phase I study. This Phase II clinical trial was devised to confirm the antitumor activity of anlotinib in patients with advanced or metastatic MTC.

METHODS

Patients with unresectable locally advanced or metastatic MTC received once daily oral anlotinib 12 mg, two weeks on/one week off, until disease progression, death, unacceptable toxicity, or withdrawal of consent for any reason. The dose was adjusted on the basis of observed toxicity. The primary endpoint was progression-free survival (PFS).

RESULTS

Fifty-eight patients received anlotinib treatment. The primary endpoint PFS has not yet been reached at the time of analysis. On the basis of investigator assessments, 56.9% of patients experienced a partial response. PFS rate at 48 weeks was 85.5%. Forty-five patients had a ≥50% decrease in serum calcitonin concentration from baseline. The most common adverse events were hand-foot syndrome, hypertriglyceridemia, cholesterol elevation, fatigue, and proteinuria.

CONCLUSIONS

Anlotinib demonstrated a durable antitumor activity with a manageable adverse event profile in locally advanced or metastatic MTC.

Medullary Thyroid Cancer: Clinical Characteristics and New Insights into Therapeutic Strategies Targeting Tyrosine Kinases

Medullary thyroid carcinoma (MTC) is a hyperplasia of thyroid C-cells, accounting for 5-10% of all thyroid cancers. MTCs may appear as sporadic or hereditary forms, and several molecules and signaling pathways have been found to function defectively in MTC cells. Tyrosine kinases are the most well-studied molecules that have abnormal function in these tumor cells. Due to their limited response, chemotherapeutic agents and radiation therapy are not effective in treating patients with advanced metastatic MTC. In the past decade, significant attention has been given to the utilization of multikinase inhibitors as targeted therapeutic agents for treating MTC patients, with the most promising results arising from the study of tyrosine kinase inhibitors, which generally bind to the ATP binding sites of these kinases. Two drugs-vandetanib and cabozantinib-are approved for the treatment of aggressive advanced MTC; however, the potential for toxicities and adverse effects of these agents on patient quality of life need to be considered against any therapeutic gain. According to recent data, it appears that inhibition of only one receptor or molecule in a pathway is not as effective as simultaneous inhibition of different pathways, indicating the need to use combination therapy. The main purpose of this review is to describe the clinical characteristics, molecular mechanisms, and current molecular and targeted therapeutic strategies active in clinical trials for advanced MTC treatment.

Quantitative Proteomics Analysis of Sporadic Medullary Thyroid Cancer Reveals FN1 as a Potential Novel Candidate Prognostic Biomarker

BACKGROUND

Sporadic medullary thyroid cancer (MTC) is a rare neuroendocrine tumor. Currently, although the diagnosis of sporadic MTC is relatively simple, the need to discover novel candidate prognostic biomarkers for sporadic MTC and investigate the underlying mechanism involved in this rare disease is urgent.

MATERIALS AND METHODS

We employed tandem mass tag-based liquid chromatography-mass spectrometry to identify and analyze differentially expressed proteins (DEPs) in sporadic MTC. Western blotting was used to validate the DEPs. Immunohistochemistry was performed to investigate FN1 and RPS6KA3 in an independent set of sporadic MTC tissues. Immunohistochemical data were analyzed by different statistical methods.

RESULTS

Three hundred eighty-eight DEPs were identified in mass spectrometry, mainly involved in the extracellular matrix, cytoskeletal remodeling, or oxidoreductase activity. Among them, THBS1, MMP9, FN1, RPS6KA3, SYT1, and carcinoembryonic antigen were successfully validated by Western blot. In addition, FN1 and RPS6KA3, enriched in extracellular matrix (ECM) remodeling and the mitogen-activated protein kinase (MAPK) signaling pathway, respectively, were investigated in an independent set of sporadic MTC tissues. Receiver-operator characteristic curve analysis showed that FN1 and RPS6KA3 can be used for discriminating sporadic MTC tumorous tissues from paired normal thyroid tissues, and the clinical biomarker calcitonin was positively correlated with FN1 and RPS6KA3 in tumorous tissues. Furthermore, the immunohistochemical scores of FN1 in tumorous tissue showed an inverse relationship with tumor classification, lymph node classification, and American Joint Committee on Cancer stage. Through univariate and multivariate analysis for progression-free survival, we also found that low FN1 expression in tumorous tissues was an independent worse prognostic factor for progression-free survival.

CONCLUSION

We identified that the pathophysiology of sporadic MTC involve numerous pathways, including the synaptic vesicle pathway, the MAPK signaling pathway, and the ECM remodeling pathway. Furthermore, our study also identified FN1 as novel prognostic biomarkers related to the pathophysiologic changes in sporadic MTC.

IMPLICATIONS FOR PRACTICE

Proteomic dissection and prognostic biomarkers are scarce in sporadic medullary thyroid cancer (MTC). This article reports the use of proteomics technology to comprehensively investigate the molecular mechanisms of sporadic MTC, which resulted in the identification of FN1 as a novel candidate prognostic biomarker.

Medullary Thyroid Cancer: Overview and Case Study of a Rare Cancer

BACKGROUND

Medullary thyroid cancer (MTC) is a rare cancer that has historically been managed by endocrinologists. In 2011, the first of several multi- targeted tyrosine kinase inhibitors was approved as treatment for MTC. These drugs have changed the management of MTC to teams that include oncologists and oncology nurses.

OBJECTIVES

This article illustrates MTC diagnostics, surveillance, management of adverse drug reactions, and disease progression through a case study.

METHODS

An overview of MTC is offered, followed by an in-depth case study that examines MTC from the patient's perspective.

FINDINGS

Oncology nurses can influence patient outcomes through the provision of patient education, support, and management of disease and treatment complications.

CXCR4/CXCR7/CXCL12 axis promotes an invasive phenotype in medullary thyroid carcinoma

Background:

Medullary thyroid carcinoma (MTC) is a rare and challenging endocrine malignancy. Once spread, the therapeutic options are limited and the outcome poor. For these patients, the identification of new druggable biological markers is of great importance. Here, we investigated the prognostic and biological role of the C-X-C chemokine receptors type 4 and 7 (CXCR4/7) in MTC.

Methods:

Eighty-six MTC and corresponding non-neoplastic thyroid specimens were immunohistochemically stained for CXCR4/7 using tissue microarray technology and expression levels correlated with clinicopathological variables. Medullary thyroid carcinoma cell line TT was treated with recombinant human SDF1α/CXCL12 (rh-SDF1α) and CXCR4 antagonists AMD3100 and WZ811. Changes in cell cycle activation, tumour cell invasiveness as well as changes in mRNA expression levels of genes associated with epithelial–mesenchymal transition (EMT) were investigated.

Results:

High CXCR4 expression was associated with large tumour size and metastatic disease. CXCR4 antagonists significantly reduced tumour cell invasiveness, while the treatment with rh-SDF1α stimulated invasive growth, caused cell cycle activation and induced EMT.

Conclusions:

The CXCR4/CXCR7/CXCL12 axis plays an important role in MTC. We provide first evidence that the chemokine receptors might serve as potential therapeutic targets in patients with advanced MTC and offer new valuable insight into the underlying molecular machinery of metastatic MTC.

A large Chinese pedigree of multiple endocrine neoplasia type 2A with a novel C634Y/D707E germline mutation in RET exon 11

The present study identified the clinical features of the largest multiple endocrine neoplasia type 2 (MEN2) A pedigree from China, with a novel double missense rearranged during transfection (RET) mutation (C634Y/D707E). To the best of our knowledge, the D707E mutation has not been identified to date. In the present study, a total of 101 family members who originated from a large pedigree (134 members in total) underwent RET mutation screening by next-generation sequencing and polymerase chain reaction (PCR) amplification, followed by direct bidirectional DNA sequencing. The clinical features of this pedigree were carefully reviewed retrospectively, and statistical analyses were conducted using SPSS software. A total of 33 (32.67%) carriers were identified to exhibit the C634Y/D707E RET germline mutation. The mean age of the patients with medullary thyroid carcinoma (MTC) identified by RET screening was 38.4±16.5 years (n=11; range, 14–65 years). Only 4 patients with pheochromocytoma with a median age of 37 years were identified. No hyperparathyroidism was diagnosed. Persistent or recurrent disease developed in the patients of the present study who underwent inappropriate initial thyroid surgeries that were performed in previous decades (III10, III23, III24, III27 and IV46, as they had undergone two surgeries prior to the present study). A total of 66.70% (6/9) of patients, following thyroidectomy, continued to develop persistent or recurrent disease during the present screening study. In total, 3 patients succumbed to MTC or distant metastasis in the present study. The increase in carcinoembryonic antigen (CEA) levels correlated with the increase in basal serum calcitonin (Ct) levels according to Pearson correlation analysis in patients with MTC without surgery. Ct and CEA levels were also significantly correlated with tumor volumes. To the best of our knowledge, the present study is the first to identify a novel double RET missense mutation in the largest MEN2A pedigree from China. Additional in-depth study is necessary to elucidate the molecular mechanisms of the D707E mutation and its potential joint effects with the other C634Y mutation in the pedigree of the present study.

Nodular Thyroid Disease and Thyroid Cancer in the Era of Precision Medicine

The management of thyroid nodules, one of the main clinical challenges in endocrine clinical practice, is usually straightforward. Although the most important concern is ruling out malignancy, there are grey areas where uncertainty is frequently present: the nodules labelled as indeterminate by cytology and the extent of therapy when thyroid cancer is diagnosed pathologically. There is evidence that the current available precision medicine tools (from all the "-omics" to molecular analysis, fine-tuning imaging or artificial intelligence) may help to fill present gaps in the future. We present here a commentary on some of the current challenges faced by endocrinologists in the field of thyroid nodules and cancer, and illustrate how precision medicine may improve their diagnostic and therapeutic capabilities in the future.

Bone Metastases and Skeletal-Related Events in Medullary Thyroid Carcinoma

CONTEXT

Bone metastases (BM) can lead to devastating skeletal-related events (SREs) in cancer patients. Data regarding medullary thyroid carcinoma (MTC) with BM are lacking.

OBJECTIVE

We evaluated the natural history of BM and SREs in MTC patients identified by a cancer center tumor registry.

SETTING

The study was conducted at a tertiary cancer center.

PATIENTS AND MAIN OUTCOME MEASURES

We retrospectively reviewed the charts of MTC patients with BM who received care from 1991 to 2014 to characterize BM and SREs.

RESULTS

Of 1008 MTC patients treated, 188 were confirmed to have BM (19%), of whom 89% (168 of 188) had nonosseous distant metastases. Median time from MTC to BM diagnosis was 30.9 months (range 0-533 mo); 25% (45 of 180) had BM identified within 3 months of MTC diagnosis. Median follow-up after detecting BM was 1.6 years (range 0-23.2 y). Most patients (77%) had six or more BM lesions, most often affecting the spine (92%) and pelvis (69%). Many patients (90 of 188, 48%) experienced one or more SREs, most commonly radiotherapy (67 of 90, 74%) followed by pathological fracture (21 of 90, 23%). Only three patients had spinal cord compression. Patients with more than 10 BM lesions were more likely to experience SREs (odds ratio 2.4; P = .007), with no difference in 5-year mortality after MTC diagnosis between patients with (31%) and without SREs (23%) (P = .11).

CONCLUSIONS

In this large retrospective series, BM in MTC was multifocal, primarily involving the spine and pelvis, supporting screening these regions for metastases in at-risk patients. SREs were common but spinal cord compression was rare. Antiresorptive therapies in this population should be investigated further with prospective trials.

Genetic and Clinical Features of Medullary Thyroid Carcinoma: The Experience of a Single Center in Costa Rica

Background. Activating mutations in the RET gene leads to medullary thyroid carcinoma (MTC). Guidelines encourage performing RET analysis in subjects with hereditary and sporadic disease. Materials and Methods. Design. Observational, case series report study. Patients. Subjects diagnosed with MTC, with a thyroidectomy performed in a single center in Costa Rica between the years 2006 and 2015. Diagnosis and Follow-Up. Pre- and postoperative calcitonin, RET mutation, and neck ultrasound and tomography were obtained. Results. 21 subjects with histological diagnosis of MTC were followed up. The average age at diagnosis was 52.0 ± 15.7 years. The preoperative mean value of calcitonin was 1340 ± 665 pg/mL. Evidence of RET mutation was found in 26.3% of the patients, with only 2 of them grouped in the same kindred. We found statistically significant differences in mean ages between mutated (38.4 ± 20.2 y) versus nonmutated RET gene (54.6 ± 11.8 y, p = 0.04). There were no significant differences regarding tumor size, metastases, and surgical reintervention. Conclusions. We report the results of RET mutation analysis in subjects with MTC in a single center of Costa Rica. The availability of this tool increases the probability of identifying familial MTC, with the benefit of detecting affected subjects and their relatives at an earlier age.

Multifocality in Sporadic Medullary Thyroid Carcinoma: An International Multicenter Study

BACKGROUND

Current surgical standard of care in sporadic medullary thyroid carcinoma (sMTC) consists of a minimum of total thyroidectomy with central neck dissection. Some have suggested thyroid lobectomy with isthmusectomy and central neck dissection for patients with sMTC, given their lower frequency of bilateral disease, although this topic has not been thoroughly studied. This study assessed the prevalence of multifocality in sMTC via a large international multi-institutional retrospective review to quantify this prevalence, including the impact of geography, to assess more accurately the risks associated with alternative surgical approaches.

METHODS

A retrospective chart review of sMTC patients from 11 institutions over 29 years (1983-2011) was undertaken. Data regarding focality, extent of disease, RET germline analysis plus family and clinical history for multiple endocrine neoplasia type 2 (MEN2), and demographic data were collected and analyzed.

RESULTS

Patients from four continents and seven countries were included in the sample. Data for 313 patients with documented sMTC were collected. Of these, 81.2% were confirmed with negative RET germline testing, while the remaining 18.8% demonstrated a negative family history and no manifestations of MEN2 syndromes other than MTC. Bilateral disease was identified in 17/306 (5.6%) patients, while multifocal disease was noted in 50/312 (16.0%) sMTC patients. When only accounting for germline negative patients, these rates were not significantly different (5.6% and 17%, respectively). Among them, when disease was unifocal in the ipsilateral lobe and isthmus, bilateral disease was present in 6/212 (2.8%) cases. When disease was multifocal in the ipsilateral lobe or isthmus, then bilateral disease was present in 8/37 (21.6%) cases (p < 0.001). No geographic differences in focality were identified.

CONCLUSIONS

The 5.6% prevalence of bilateral foci in sMTC suggests that total thyroidectomy should remain the standard of care for initial surgery, as less complete thyroid surgery may fail to address fully the primary site of disease. Whether ipsilateral tumor focality should be an independent factor determining the need for completion thyroidectomy when sMTC is diagnosed after hemithyroidectomy remains to be determined.

Systemic treatment and management approaches for medullary thyroid cancer

Although rare, medullary thyroid cancer (MTC) exemplifies the value that ever-expanding knowledge of molecular pathways and mechanisms brings to managing challenging cancers. Although surgery can be curative for MTC in many patients, a substantial proportion of patients present with locoregional or distant metastatic disease. Once distant disease occurs, treatment options are limited, and conventional cancer treatments such as cytotoxic chemotherapy are of minimal benefit. Biomarkers such as calcitonin and carcinoembryonic antigen are important correlates of disease burden as well as predictors of disease progress, including recurrence and survival. MTC is either sporadic (∼75%) or inherited (∼25%) as an autosomal dominant disease. Regardless, germline and somatic mutations, particularly in the rearranged during transfection (RET) proto-oncogene, are key factors in the neoplastic process. Gain-of-function RET mutations result in overactive proteins that lead to abnormal activation of downstream signal transduction pathways, resulting in ligand-independent growth and resistance to apoptotic stimuli. Specific RET mutation variants have been found to correlate with phenotype and natural history of MTC with some defects portending a more aggressive clinical course. Greater understanding of the consequence of the aberrant signaling pathway has fostered the development of targeted therapies. Two small-molecule tyrosine kinase inhibitors, vandetanib and cabozantinib, are currently available as approved agents for the treatment of advanced or progressive MTC and provide significant increases in progression-free survival. Since there have been no head-to-head comparisons, clinicians often select between these agents on the basis of familiarity, patient characteristics, comorbidities, and toxicity profile.

Preclinical testing of selective Aurora kinase inhibitors on a medullary thyroid carcinoma-derived cell line

Deregulated expression of the Aurora kinases (Aurora-A, B, and C) is thought to be involved in cell malignant transformation and genomic instability in several cancer types. Over the last decade, a number of small-molecule inhibitors of Aurora kinases have been developed, which have proved to efficiently restrain malignant cell growth and tumorigenicity. Regarding medullary thyroid carcinoma (MTC), we previously showed the efficacy of a pan-Aurora kinase inhibitor (MK-0457) in impairing growth and survival of the MTC-derived cell line TT. In the present study, we sought to establish if one of the Aurora kinases might represent a preferential target for MTC therapy. The effects of selective inhibitors of Aurora-A (MLN8237) and Aurora-B (AZD1152) were analyzed on TT cell proliferation, apoptosis, cell cycle, and ploidy. The two inhibitors reduced TT cell proliferation in a time- and dose-dependent manner, with IC50 of 19.0 ± 2.4 nM for MLN8237 and 401.6 ± 44.1 nM for AZD1152. Immunofluorescence experiments confirmed that AZD1152 inhibited phosphorylation of histone H3 (Ser10) by Aurora-B, while it did not affect Aurora-A autophosphorylation. MLN8237 inhibited Aurora-A autophosphorylation as expected, but at concentrations required to achieve the maximum antiproliferative effects it also abolished H3 (Ser10) phosphorylation. Cytofluorimetry experiments showed that both inhibitors induced accumulation of cells in G2/M phase and increased the subG0/G1 fraction and polyploidy. Finally, both inhibitors triggered apoptosis. We demonstrated that inhibition of either Aurora-A or Aurora-B has antiproliferative effects on TT cells, and thus it would be worthwhile to further investigate the therapeutical potential of Aurora kinase inhibitors in MTC treatment.

Survivin and XIAP: two valuable biomarkers in medullary thyroid carcinoma

Background:

Medullary thyroid carcinoma (MTC) accounts for ∼5% of all thyroid malignancies. To date, surgery is the first-line therapy with curative intention. However, for advanced MTC, conventional chemotherapeutic agents do not provide convincing results. Therefore, the identification of biomarkers that can be antagonised by small-molecule therapeutics may lead to novel encouraging treatment options.

Methods:

Seventy-nine patients with surgically resected and histologically confirmed MTC were included in this study. Tissue microarrays were constructed to assess the relationship between inhibitor of apoptosis proteins (IAPs) survivin or XIAP expression levels and clinicopathological variables as well as overall survival.

Results:

High survivin or XIAP expression was associated with an advanced T-stage and metastatic disease. Whereas tissue expression levels of survivin correlated with serum calcitonin levels, XIAP was overexpressed in the subgroup of patients with sporadic MTC. Both IAPs were negatively associated with patient survival in the multivariate Cox regressions analysis (survivin: hazard ratio (HR) 1.62; 95% confidence interval (CI): 1.21–2.16; P=0.001; XIAP: HR 1.78; 95% CI: 1.16–2.72; P=0.008).

Conclusions:

Survivin and XIAP demonstrate distinct expression patterns in MTCs, which are associated with advanced disease and poor prognosis. We thus provide first evidence that both IAPs might serve as viable targets in patients with MTC.

Consensus on management of advanced medullary thyroid carcinoma on behalf of the Working Group of Thyroid Cancer of the Spanish Society of Endocrinology (SEEN) and the Spanish Task Force Group for Orphan and Infrequent Tumors (GETHI)

BACKGROUND

Of all thyroid cancers, <5 % are medullary (MTC). It is a well-characterized neuroendocrine tumor arising from calcitonin-secreting C cells, and RET gene plays a central role on its pathogeny.

METHODS

The electronic search was conducted using MEDLINE (PubMed), EMBASE and Cochrane Central Register of Controlled Trials. Quality assessments of selected current articles, guidelines and reviews of MTC were performed.

RESULTS

This consensus updates and summarizes biology, treatment and prognostic considerations of MTC.

CONCLUSIONS

Multidisciplinary teams and specialized centers are recommended for the management of MTC patients. In the metastatic setting, those patients with large volume of disease are candidates to start systemic treatment mainly if they are symptomatic and the tumor has progressed in the last 12-14 months. Wait and see strategy should be offered to patients with: disseminated disease with only high levels of calcitonin and no macroscopic structural disease, low burden and absence of progression.

RAS proto-oncogene in medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare malignancy originating from the calcitonin-secreting parafollicular thyroid C cells. Approximately 75% of cases are sporadic. Rearranged during transfection (RET) proto-oncogene plays a crucial role in MTC development. Besides RET, other oncogenes commonly involved in the pathogenesis of human cancers have also been investigated in MTC. The family of human RAS genes includes the highly homologous HRAS, KRAS, and NRAS genes that encode three distinct proteins. Activating mutations in specific hotspots of the RAS genes are found in about 30% of all human cancers. In thyroid neoplasias, RAS gene point mutations, mainly in NRAS, are detected in benign and malignant tumors arising from the follicular epithelium. However, recent reports have also described RAS mutations in MTC, namely in HRAS and KRAS. Overall, the prevalence of RAS mutations in sporadic MTC varies between 0-43.3%, occurring usually in tumors with WT RET and rarely in those harboring a RET mutation, suggesting that activation of these proto-oncogenes represents alternative genetic events in sporadic MTC tumorigenesis. Thus, the assessment of RAS mutation status can be useful to define therapeutic strategies in RET WT MTC. MTC patients with RAS mutations have an intermediate risk for aggressive cancer, between those with RET mutations in exons 15 and 16, which are associated with the worst prognosis, and cases with other RET mutations, which have the most indolent course of the disease. Recent results from exome sequencing indicate that, besides mutations in RET, HRAS, and KRAS, no other recurrent driver mutations are present in MTC.

Consensus on the management of advanced medullary thyroid carcinoma on behalf of the Working Group of Thyroid Cancer of the Spanish Society of Endocrinology (SEEN) and the Spanish Task Force Group for Orphan and Infrequent Tumors (GETHI)

BACKGROUND

In Spain medullary thyroid carcinoma (MTC) would not exceed 80 new cases per year and less than half of them would be good candidates for systemic treatment with novel agents.

METHODS

Relevant literature was reviewed, including PubMed searches supplemented with additional articles.

RESULTS

The consensus summarizes the clinical outcomes in terms of activity and toxicity of each of the available drugs. A brief summary of the minimum requirements in terms of follow up and genetic counseling around MTC is also included.

CONCLUSIONS

Only those patients with objective imaging progression in the last 12-14 months with large volume of disease are clear candidates to start systemic treatment. However, those patients with low disease volume should be considered for 'wait and see' strategy until symptoms of the disease appear. Multidisciplinary approach for the management of MTC patient is mandatory nowadays.