Prognostic significance of somatic RET oncogene mutations in sporadic medullary thyroid cancer: a 10-year follow-up study

Treatment of RET-Positive Advanced Medullary Thyroid Cancer with Multi-Tyrosine Kinase Inhibitors—A Retrospective Multi-Center Registry Analysis

Simple Summary

Lately, a more personalized approach in the management of advanced thyroid cancer patients has improved the outcomes, and several novel molecularly guided therapies, including selective RET inhibitors (sRETis), have demonstrated promising efficacy in clinical trials. RET (rearranged during transfection) variants are the most prevalent oncogenic event in medullary thyroid cancer (MTC). We here found RET oncogene variants in 44/48 prospectively collected MTC tumor samples from patients treated with more unselective kinase inhibitors vandetanib and/or cabozantinib. Our study shows that RET variants were highly prevalent in patients with advanced MTC, and the treatment results in RET-positive cases were similar to those reported in unselected cohorts.

Abstract

Background: RET (rearranged during transfection) variants are the most prevalent oncogenic events in medullary thyroid cancer (MTC). In advanced disease, multi-tyrosine kinase inhibitors (MKIs) cabozantinib and vandetanib are the approved standard treatment irrespective of RET status. The actual outcome of patients with RET-positive MTC treated with MKIs is ill described. Methods: We here retrospectively determined the RET oncogene variant status with a targeted DNA Custom Panel in a prospectively collected cohort of 48 patients with advanced MTC treated with vandetanib and/or cabozantinib at four German referral centers. Progression-free survival (PFS) and overall survival (OS) probabilities were estimated using the Kaplan-Meier method. Results: In total, 44/48 (92%) patients had germline or somatic RET variants. The M918T variant was found in 29/44 (66%) cases. In total, 2/32 (6%) patients with a somatic RET variant had further somatic variants, while in 1/32 (3%) patient with a germline RET variant, additional variants were found. Only 1/48 (2%) patient had a pathogenic HRAS variant, and no variants were found in 3 cases. In first-line treatment, the median OS was 53 (95% CI (95% confidence interval), 32–NR (not reached); n = 36), and the median PFS was 21 months (12–39; n = 33) in RET-positive MTC patients. In second-line treatment, the median OS was 18 (13–79; n = 22), and the median PFS was 3.5 months (2–14; n = 22) in RET-positive cases. Conclusions: RET variants were highly prevalent in patients with advanced MTC. The treatment results in RET-positive cases were similar to those reported in unselected cohorts.

Management of medullary carcinoma of the thyroid: a review

Medullary thyroid carcinoma (MTC) is an uncommon malignancy of neuroendocrine origin derived from the parafollicular C cells. Although infrequent, the interest in this cancer exceeds its incidence owing to its distinctive features and its characteristic association with other endocrine tumors. Although the majority of MTCs are sporadic, hereditary varieties occur in isolation or as a part of multiple endocrine neoplasia type 2 syndrome (MEN 2). Currently, complete surgical resection of the tumor and nodal metastases with a curative intent remains the mainstay of therapy. The role of adjuvant therapy is limited, although radiotherapy and newer targeted therapies are routinely used for metastatic disease. The lack of consensus in the available guidance regarding the most appropriate diagnostic, therapeutic and follow-up strategies has caused substantial variability in clinical practice. Therefore, this review summarizes the latest available evidence and guidelines on the management of MTC with an emphasis on diagnosis, surgical treatment and follow-up.

Surgical selection and prognostic analysis in patients with unilateral sporadic medullary thyroid carcinoma

PURPOSE

The extent of thyroid surgery and cervical lymph node dissection of unilateral sporadic medullary thyroid carcinoma (sMTC) is still controversial, and the aim of this study was to investigate whether hemithyroidectomy was adequate as a locally curative surgery for patients with unilateral sMTC.

METHODS

This study is a retrospective case series of patients with sMTC who underwent curative total thyroidectomy or hemithyroidectomy in our institution from January 2011 to December 2019.

RESULTS

In total, 129 patients who met the inclusion criteria were enrolled including 49 (38.0%) patients who underwent total thyroidectomy and 80 (62.0%) patients who underwent hemithyroidectomy. About 80 (62.0%) patients achieved a biochemical cure (BC), whereas there was no significant difference between two groups in biochemical cure rate (61.2% versus 62.5%, P = 0.885). A logistic regression analysis showed a strong negative correlation between the factors of preoperative calcitonin level and pTNM stage and biochemical cure. In the log-rank test, no significant difference in OS (P = 0.314) and DFS (P = 0.409) was found between the two surgical groups. Lateral cervical lymph node metastasis and pTNM stage were significant prognostic factors affecting DFS in univariate analysis; moreover, absence of biochemical cure, tumor size ≥ 4 cm and lateral cervical lymph node metastasis were independent risk factors of unilateral sMTC patients in our analysis.

CONCLUSION

For patients with unilateral sMTC, hemithyroidectomy was adequate as a locally curative surgery, because the patients underwent total thyroidectomy did not benefit more from it in the aspects of BC/OS/RFS, while the postoperative increasing incidence rate of postoperative hypocalcemia could not improve patients' quality of life.

Medullary thyroid cancer with ectopic Cushing's syndrome: A multicentre case series

OBJECTIVE

Ectopic Cushing's syndrome (ECS) induced by medullary thyroid cancer (MTC) is rare, and data on clinical characteristics, treatment and outcome are limited.

DESIGN

Retrospective cohort study in three German and one Swiss referral centres.

PATIENTS

Eleven patients with MTC and occurrence of ECS and 22 matched MTC patients without ECS were included.

MEASUREMENTS

The primary endpoint of this study was the overall survival (OS) in MTC patients with ECS versus 1:2 matched MTC patients without ECS.

RESULTS

The median age at diagnosis of ECS was 59 years (range: 35-81) and the median time between initial diagnosis of MTC and diagnosis of ECS was 29 months (range: 0-193). Median serum morning cortisol was 49 µg/dl (range: 17-141, normal range: 6.2-18). Eight (73%) patients received treatment for ECS. Treatment of ECS consisted of bilateral adrenalectomy (BADX) in four (36%) patients and adrenostatic treatment in eight (73%) patients. One patient received treatment with multityrosine kinase inhibitor (MKI) to control hypercortisolism. All patients experienced complete resolution of symptoms of Cushing's syndrome and biochemical control of hypercortisolism. Patients with ECS showed a shorter median OS of 87 months (95% confidence interval [95% CI]: 64-111) than matched controls (190 months, 95% CI: 95-285). Of the nine deaths, four were related to progressive disease (PD). Four patients showed PD as well as complications and comorbidities of hypercortisolism before death.

CONCLUSION

This study shows that ECS occurs in advanced stage MTC and is associated with a poor prognosis. Adrenostatic treatment and BADX were effective systemic treatment options in patients with MTC and ECS to control their hypercortisolism. MKI treatment achieved complete remission of hypercortisolism and sustained tumour control in one treated case.

Sporadic Medullary Thyroid Carcinoma: Towards a Precision Medicine

Medullary thyroid carcinoma (MTC) is a neuroendocrine malignant tumor originating from parafollicular C-cells producing calcitonin. Most of cases (75%) are sporadic while the remaining (25%) are hereditary. In these latter cases medullary thyroid carcinoma can be associated (multiple endocrine neoplasia type IIA and IIB) or not (familial medullary thyroid carcinoma), with other endocrine diseases such as pheochromocytoma and/or hyperparathyroidism. RET gene point mutation is the main molecular alteration involved in MTC tumorigenesis, both in sporadic and in hereditary cases. Total thyroidectomy with prophylactic/therapeutic central compartment lymph nodes dissection is the initial treatment of choice. Further treatments are needed according to tumor burden and rate of progression. Surgical treatments and local therapies are advocated in the case of single or few local or distant metastasis and slow rate of progression. Conversely, systemic treatments should be initiated in cases with large metastatic and rapidly progressive disease. In this review, we discuss the details of systemic treatments in advanced and metastatic sporadic MTC, focusing on multikinase inhibitors, both those already used in clinical practice and under investigation, and on emerging treatments such as highly selective RET inhibitors and radionuclide therapy.

Surgical aspects and controversies in the management of medullary thyroid cancer

Medullary thyroid cancer (MTC) accounts for only 4% of thyroid carcinomas but 15% of thyroid cancer deaths. MTC is a tumour of the calcitonin secreting parafollicular C cells in the thyroid which can occur sporadically or be hereditary in multiple endocrine neoplasias type 2 syndromes due to germline RET mutations. Sporadic forms of MTC can also be caused by mutations in the RET protooncogene. MTC commonly presents in a late stage, with 70% of patients presenting with local nodal metastasis. Currently, the only curative treatment for MTC is surgical removal. The aim of this paper is to describe the current guidelines and progressions of the surgical management of MTC and to highlight up-and-coming chemotherapies. A database literature review was completed utilizing PubMed to cumulate the extant literature, screening for most recent guidelines and publications regarding the management of MTC. Current guidelines were described by the American Thyroid Association in 2015. Controversial publications continue to present supporting evidence for varying degrees of thyroidectomy and neck dissections. Recently, researchers have been exploring non-surgical options including external beam radiotherapy and multikinase inhibitors such as vandetanib and cabozantinib for the treatment of MTC. Surgical management of MTC remains controversial and varies significantly dependent on the extent of disease. Chemotherapeutic options have undetermined effects on survival to date.

International Medullary Thyroid Carcinoma Grading System: A Validated Grading System for Medullary Thyroid Carcinoma

PURPOSE

Medullary thyroid carcinoma (MTC) is an aggressive neuroendocrine tumor (NET) arising from the calcitonin-producing C cells. Unlike other NETs, there is no widely accepted pathologic grading scheme. In 2020, two groups separately developed slightly different schemes (the Memorial Sloan Kettering Cancer Center and Sydney grade) on the basis of proliferative activity (mitotic index and/or Ki67 proliferative index) and tumor necrosis. Building on this work, we sought to unify and validate an internationally accepted grading scheme for MTC.

PATIENTS AND METHODS

Tumor tissue from 327 patients with MTC from five centers across the United States, Europe, and Australia were reviewed for mitotic activity, Ki67 proliferative index, and necrosis using uniform criteria and blinded to other clinicopathologic features. After reviewing different cutoffs, a two-tiered consensus grading system was developed. High-grade MTCs were defined as tumors with at least one of the following features: mitotic index ≥ 5 per 2 mm², Ki67 proliferative index ≥ 5%, or tumor necrosis.

RESULTS

Eighty-one (24.8%) MTCs were high-grade using this scheme. In multivariate analysis, these patients demonstrated decreased overall (hazard ratio [HR] = 11.490; 95% CI, 3.118 to 32.333; P < .001), disease-specific (HR = 8.491; 95% CI, 1.461 to 49.327; P = .017), distant metastasis-free (HR = 2.489; 95% CI, 1.178 to 5.261; P = .017), and locoregional recurrence-free (HR = 2.114; 95% CI, 1.065 to 4.193; P = .032) survivals. This prognostic power was maintained in subgroup analyses of cohorts from each of the five centers.

CONCLUSION

This simple two-tiered international grading system is a powerful predictor of adverse outcomes in MTC. As it is based solely on morphologic assessment in conjunction with Ki67 immunohistochemistry, it brings the grading of MTCs in line with other NETs and can be readily applied in routine practice. We therefore recommend grading of MTCs on the basis of mitotic count, Ki67 proliferative index, and tumor necrosis.

[Molecular genotyping in refractory thyroid cancers in 2021: When, how and why? A review from the TUTHYREF network]

Refractory thyroid cancers include radio-iodine-refractory cancers, metastatic or locally advanced unresectable medullary and anaplastic thyroid cancers. Their management has been based for several years on the use of multi-target kinase inhibitors, with anti-angiogenic action, with the exception of anaplastic cancers usually treated with chemo- and radiotherapy. The situation has recently evolved due to the availability of molecular genotyping techniques allowing the discovery of rare but targetable molecular abnormalities. New treatment options have become available, more effective and less toxic than the previously available multi-target kinase inhibitors. The management of refractory thyroid cancers is therefore becoming more complex both at a diagnosis level with the need to know when, how and why to look for these molecular abnormalities but also at a therapeutic level, innovative treatments being hardly accessible. The cost of molecular analyzes and the access to treatments need also to be homogenized because disparities could lead to inequality of care at a national or international level. Finally, the strategy of identifying molecular alterations and treating these rare tumors reinforces the importance of a discussion in a multidisciplinary consultation meeting.

Choroidal metastasis as initial presentation of aggressive medullary thyroid carcinoma with widespread mediastinal, brain, pituitary, bone, lung, and liver metastasis: Case report and literature review

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor that originates from the parafollicular C cells of the thyroid gland. MTC can be due to sporadic or hereditary causes due to gain of function germ line mutations in the RET proto-oncogene. MTC presenting as ocular symptoms due to choroidal mass is rare with bad prognosis.

PRESENTATION OF CASE

A 38-year-old Sudanese male presented to Hamad General Hospital, complaining of sudden painless decrease of vision of the right eye of 3 weeks duration. After investigations using imaging methods, the patient was discovered to have metastatic MTC that presented as choroidal mass and metastasized to his lung, bone, brain, pituitary, liver and mediastinum.

DISCUSSION

In terms of investigations, serum levels of calcitonin have superior diagnostic accuracy. Our patient undertook diagnostic imaging including ultrasonography, fine needle aspiration and computerized tomography (CT) scan and/or MRI imaging. He undertook total thyroidectomy and left neck dissection followed by stereotactic radiosurgery for the right orbit and pituitary. He then received systemic anti-RET therapy (Selpercatinib). At 5 months follow up there was dramatic drop in CEA from 888 μg/L to 164 μg/L, and calcitonin from >585.2 pmol/L to 354 pmol/L.

CONCLUSION

Choroidal metastasis as initial presentation of MTC is extremely rare and challenging to diagnose. Surgeons need a high index of suspicion when ocular symptoms accompany a neck mass or thyroid-related symptoms. MTC has a progressive course with involvement of blood vessels and neck lymph nodes. Choroidal metastasis of MTC is challenging to manage.

Hallmarks of RET and Co-occuring Genomic Alterations in RET-aberrant Cancers

Activating receptor-tyrosine kinase rearranged during transfection (RET) mutations and fusions are potent drivers of oncogenesis. The recent FDA approvals of highly potent and selective RET inhibitors, selpercatinib and pralsetinib, has altered the therapeutic management of RET aberrant tumors. There is ample evidence of the role of RET signaling in certain cancers. RET aberrations as fusions or mutations occur in multiple cancers, however, there is considerable phenotypic diversity. There is emerging data on the lack of responsiveness of immunotherapy in RET-altered cancers. Herein, we review the registrational data from the selective RET-inhibitor trials, and comprehensively explore RET alterations in pan-cancer adult malignancies and their co-alterations. These co-occuring alterations may define the future of RET inhibition from specific selective targeting to customized combination therapies as data are rapidly emerging on both on-target and off-target acquired resistance mechanisms. Fascinatingly, oncogenic RET fusions have been reported to mediate resistance to EGFR inhibition and KRAS^G12C inhibition.

Progress in Treating Advanced Thyroid Cancers in the Era of Targeted Therapy

Background: Thyroid cancer is a common malignancy whose detection has increased significantly in past decades. Most of the increased incidence is due to detection of early well-differentiated thyroid cancer, but the incidence of more advanced thyroid cancers has increased as well. Recent methodological advancements have allowed for a deep understanding of the molecular underpinnings of the various types of thyroid cancer. Summary: Thyroid cancers harbor a high frequency of potential druggable molecular alterations, including the highest frequency of oncogenic driver kinase fusions seen across all solid tumors. Analyses of poorly differentiated and anaplastic thyroid carcinoma confirmed that these tumors develop from more well-differentiated follicular-derived thyroid cancers through acquired additional mutations. The recognition of driver genomic alterations in thyroid cancers not only predicts tumor phenotype but also now can inform treatment approaches. Conclusions: Major progress in understanding the oncogenic molecular underpinnings across the array of thyroid cancers has led to considerable gains in gene-specific systemic therapies for many cancers. This article focuses on the molecular characteristics of aggressive follicular-derived thyroid cancers and medullary thyroid cancer and highlights advancements in treating thyroid cancer in the era of targeted therapy.

Immune Profiling of Medullary Thyroid Cancer-An Opportunity for Immunotherapy

Medullary thyroid cancer (MTC) is a rare malignancy that arises from calcitonin-producing C-cells. Curative treatment for patients with metastatic MTC is challenging. Identifying the mechanisms by which cancer cells inhibit the activity of immune cells provides an opportunity to develop new therapies that restore anticancer activity. Little is known about the immunological phenomena underlying MTC. Here, we examined the expression profile of 395 genes associated with MTC. The study included 51 patients diagnosed with MTC at a single center. Bioinformatical analysis revealed that CD276 expression in MTC cells was at least three-fold higher than that in normal tissue. The expression of CD276 showed a weak but statistically significant positive correlation with tumor diameter, but we did not find a significant association between CD276 expression and other histopathological clinical factors, or the response to initial therapy. A search of published data identified the monoclonal antibody (inhibitor) enoblituzumab as a potential drug for patients diagnosed with MTC overexpressing CD276.

Targeting Rearranged during Transfection in Cancer: A Perspective on Small-Molecule Inhibitors and Their Clinical Development

Rearranged during transfection (RET) is a receptor tyrosine kinase essential for the normal development and maturation of a diverse range of tissues. Aberrant RET signaling in cancers, due to RET mutations, gene fusions, and overexpression, results in the activation of downstream pathways promoting survival, growth, and metastasis. Pharmacological manipulation of RET is effective in treating RET-driven cancers, and efforts toward developing RET-specific therapies have increased over the last 5 years. In 2020, RET-selective inhibitors pralsetinib and selpercatinib achieved clinical approval, which marked the first approvals for kinase inhibitors specifically developed to target the RET oncoprotein. This Perspective discusses current development and clinical applications for RET precision medicine by providing an overview of the incremental improvement of kinase inhibitors for use in RET-driven malignancies.

Similar Stage-dependent Survival and Outcome in Sporadic and Hereditary Medullary Thyroid Carcinoma

CONTEXT

Long-term data are scarce on large cohorts with sporadic (sMTC) and hereditary medullary thyroid carcinoma (hMTC).

OBJECTIVES

To compare long-term disease-specific survival (DSS) and outcomes between sMTC and hMTC groups.

DESIGN

Retrospective analysis.

SETTING

German tertiary referral center.

PATIENTS

A total of 673 patients with MTC that underwent surgery from January 1974 to July 2019.

INTERVENTION

None (observational study).

MAIN OUTCOME MEASURE

Differences between sMTC and hMTC in long-term, stage-dependent survival and outcomes.

RESULTS

Surgery was performed at median ages of 49 years for sMTC (n = 477, 44% male) and 29 years for hMTC (n = 196, 43% male; P < 0.0001). The mean follow-up times were 9.2 ± 8.0 (sMTC) and 14.6 ± 10.3 years (hMTC). Age and tumor stage at diagnosis were significantly different between the 2 groups (P < 0.0001). The sMTC and hMTC groups had different overall DSS (log rank, P = 0.0183), but similar stage-dependent DSS (log rank, P = 0.1242-0.8981). In a multivariate analysis, sMTC and hMTC did not differ in DSS (hazard ratio [HR] = 1.56; 95% CI, 0.94-2.57), but in both groups, a worse DSS was significantly associated with age at diagnosis (HR = 1.04; 95% CI, 1.02-1.05), male sex (HR = 0.49; 95% CI, 0.32-0.76), and stages III and IV at diagnosis (HR = 20.00; 95% CI, 2.74-145.91 and HR = 97.47; 95% CI, 13.07-726.67, respectively). The groups had significantly different (P < 0.0001) outcomes (i.e., cured, minimal residual disease, structural detectable disease, and death), but similar stage-dependent outcomes (P = 0.9449-0.0511), except for stage III (P = 0.0489).

CONCLUSION

Patients with sMTC and hMTC had different ages of onset, but similar stage-dependent DSS and outcomes after the MTC diagnosis. This finding suggested that tumor behavior was similar in sMTC and hMTC.

Pralsetinib for patients with advanced or metastatic RET-altered thyroid cancer (ARROW): a multi-cohort, open-label, registrational, phase 1/2 study

BACKGROUND

Oncogenic alterations in RET represent important therapeutic targets in thyroid cancer. We aimed to assess the safety and antitumour activity of pralsetinib, a highly potent, selective RET inhibitor, in patients with RET-altered thyroid cancers.

METHODS

ARROW, a phase 1/2, open-label study done in 13 countries across 71 sites in community and hospital settings, enrolled patients 18 years or older with RET-altered locally advanced or metastatic solid tumours, including RET-mutant medullary thyroid and RET fusion-positive thyroid cancers, and an Eastern Co-operative Oncology Group performance status of 0-2 (later limited to 0-1 in a protocol amendment). Phase 2 primary endpoints assessed for patients who received 400 mg once-daily oral pralsetinib until disease progression, intolerance, withdrawal of consent, or investigator decision, were overall response rate (Response Evaluation Criteria in Solid Tumours version 1.1; masked independent central review) and safety. Tumour response was assessed for patients with RET-mutant medullary thyroid cancer who had received previous cabozantinib or vandetanib, or both, or were ineligible for standard therapy and patients with previously treated RET fusion-positive thyroid cancer; safety was assessed for all patients with RET-altered thyroid cancer. This ongoing study is registered with clinicaltrials.gov, NCT03037385, and enrolment of patients with RET fusion-positive thyroid cancer was ongoing at the time of this interim analysis.

FINDINGS

Between Mar 17, 2017, and May 22, 2020, 122 patients with RET-mutant medullary and 20 with RET fusion-positive thyroid cancers were enrolled. Among patients with baseline measurable disease who received pralsetinib by July 11, 2019 (enrolment cutoff for efficacy analysis), overall response rates were 15 (71%) of 21 (95% CI 48-89) in patients with treatment-naive RET-mutant medullary thyroid cancer and 33 (60%) of 55 (95% CI 46-73) in patients who had previously received cabozantinib or vandetanib, or both, and eight (89%) of nine (95% CI 52-100) in patients with RET fusion-positive thyroid cancer (all responses confirmed for each group). Common (≥10%) grade 3 and above treatment-related adverse events among patients with RET-altered thyroid cancer enrolled by May 22, 2020, were hypertension (24 patients [17%] of 142), neutropenia (19 [13%]), lymphopenia (17 [12%]), and anaemia (14 [10%]). Serious treatment-related adverse events were reported in 21 patients (15%), the most frequent (≥2%) of which was pneumonitis (five patients [4%]). Five patients [4%] discontinued owing to treatment-related events. One (1%) patient died owing to a treatment-related adverse event.

INTERPRETATION

Pralsetinib is a new, well-tolerated, potent once-daily oral treatment option for patients with RET-altered thyroid cancer.

FUNDING

Blueprint Medicines.

Diagnostic RET genetic testing in 1,058 index patients: A UK centre perspective

OBJECTIVE

Diagnostic germline RET analysis is offered to all patients with a diagnosis of medullary thyroid carcinoma (MTC), or other conditions associated with multiple endocrine neoplasia type 2 (MEN2) in the United Kingdom. Here, we report the experience of a single centre's germline RET analysis over a 21-year period.

DESIGN

Retrospective case-note review.

PATIENTS

All index patients referred to the Exeter Genomics Laboratory for diagnostic germline RET analysis between 1997 and 2018, and unaffected family members, undergoing predictive testing.

MEASUREMENTS

The rate and nature of pathogenic variant detection were recorded, as well as the indication for testing.

RESULTS

1,058 index patients and 551 unaffected family members were tested. The overall rate of pathogenic variant detection was 10.2% amongst index patients and 29% amongst unaffected family members. The commonest indication was isolated MTC, and amongst the 690 patients with isolated MTC, 68 (9.9%) were found to harbour a RET pathogenic variant. Of those with presumed sporadic MTC, 8.5% were found to harbour germline RET pathogenic variants, compared with 36.4% of those with a family history of MEN2-associated conditions. Pathogenic variants were identified in 3.6% and 0% of patients with isolated phaeochromocytoma and primary hyperparathyroidism, respectively.

CONCLUSIONS

Although the detection rate of RET germline pathogenic variants in patients with presumed sporadic MTC was significant, the overall detection rate in those with MTC was lower than expected in this series. Advances in RET analysis in response to reports of new variants over the last two decades are likely to have improved the pick-up rate in recent years.

Evaluation of grade in a genotyped cohort of sporadic medullary thyroid carcinomas

AIMS

Tumour grade and RET mutation status, especially the presence of high-risk exon 15 and 16 RET mutations, have been reported to be prognostic in patients with sporadic medullary thyroid carcinoma (MTC). The aims of our study were to evaluate the performance of two recently proposed grading systems and to assess the association between grade and genotype in a cohort of sporadic MTCs.

METHODS AND RESULTS

We identified 44 sporadic MTCs. All available tumour slides were examined, and cases were assigned a grade on the basis of either mitotic count and tumour necrosis, or mitotic count, tumour necrosis, and Ki-67 proliferative index, as described in two recent studies. Additional clinicopathological features and outcome information were obtained from the pathology reports and electronic medical records. The presence of RET and RAS mutations was determined either with direct sequencing or with massively parallel sequencing. Both grading systems were prognostic for progression-free survival and disease-specific survival on univariate analysis. There was no correlation between grade and mutation status. Specifically, neither RET nor high-risk RET mutations were enriched in high-grade tumours, as assessed by either grading scheme.

CONCLUSION

Our findings suggest that grade is not correlated with RET/RAS mutation status, indicating that grade and genotype may give independent prognostic information.

RET Regulates Human Medullary Thyroid Cancer Cell Proliferation through CDK5 and STAT3 Activation

Medullary thyroid cancer (MTC) is a neuroendocrine tumor that arises from the parafollicular C-cells, which produces the hormone calcitonin. RET is a transmembrane receptor protein-tyrosine kinase, which is highly expressed in MTC. Our previous studies reported that cyclin-dependent kinase 5 (CDK5) plays a crucial role in cancer progression, including MTC. However, the role of CDK5 in GDNF-induced RET signaling in medullary thyroid cancer proliferation remains unknown. Here, we investigated RET activation and its biochemically interaction with CDK5 in GDNF-induced medullary thyroid cancer proliferation. Our results demonstrated that GDNF stimulated RET phosphorylation and thus subsequently resulted in CDK5 activation by its phosphorylation. Activated CDK5 further caused STAT3 activation by its specific phosphorylation at Ser727. Moreover, we also found that GDNF treatment enhanced ERK1/2 and EGR1 activity, which is involved in p35 activation. Interestingly, we identified for the first time that CDK5 physically interacted with RET protein in MTC. Overall, our results provide a new mechanism for medullary thyroid cancer cell proliferation, suggesting that targeting CDK5 may be a promising therapeutic candidate for human medullary thyroid cancer in the near future.

Genetic Predisposition to Numerous Large Ulcerating Basal Cell Carcinomas and Response to Immune Therapy

Objective:

Well-defined germ-line mutations in the PTCH1 gene are associated with syndromic multiple basal cell carcinomas (BCCs). Here, we used whole exome sequencing (WES) to identify the role of patched-1 in patients with multiple, unusually large BCCs.

Methods:

A 72-year old patient presenting with numerous BCCs progressing to large ulcerating lesions was enrolled. WES was used to identify the pathogenic gene locus.

Results:

Genetic work-up by WES identified a homozygous PTCH1 nonsense mutation in the tumor tissue but not present in her blood cells or in non-lesional skin. In addition, heterozygous missense mutations were identified in three cancer-associated genes (EPHB2, RET, and GALNT12) in blood cells as well as in lesional and non-lesional skin. We also tested systemic immune therapy as a potentially beneficial approach to treat patients with numerous large BCCs on scatted areas of involvement. A rapid and sustained response to nivolumab was noted, suggesting that it is an efficacious drug for long-term therapeutic outcome.

Conclusion:

PTCH1, EPHB2, RET, and GALNT12 may potentially contribute to the synergistic oncogene driven malignant transformation manifesting as multiple, unusually large BCCs.

The importance of the RET gene in thyroid cancer and therapeutic implications

Since the discovery of the RET receptor tyrosine kinase in 1985, alterations of this protein have been found in diverse thyroid cancer subtypes. RET gene rearrangements are observed in papillary thyroid carcinoma, which result in RET fusion products. By contrast, single amino acid substitutions and small insertions and/or deletions are typical of hereditary and sporadic medullary thyroid carcinoma. RET rearrangements and mutations of extracellular cysteines facilitate dimerization and kinase activation, whereas mutations in the RET kinase coding domain drive dimerization-independent kinase activation. Thus, RET kinase inhibition is an attractive therapeutic target in patients with RET alterations. This approach was initially achieved using multikinase inhibitors, which affect multiple deregulated pathways that include RET kinase. In clinical practice, use of multikinase inhibitors in patients with advanced thyroid cancer resulted in therapeutic efficacy, which was associated with frequent and sometimes severe adverse effects. However, remarkable progress has been achieved with the identification of novel potent and selective RET kinase inhibitors for the treatment of advanced thyroid cancer. Although expanded clinical validation in future trials is needed, the sustained antitumoural activity and the improved safety profile of these novel compounds is opening a new exciting era in precision oncology for RET-driven cancers.

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.

Real-World Efficacy and Safety of Cabozantinib and Vandetanib in Advanced Medullary Thyroid Cancer

Background: Management of patients with advanced medullary thyroid cancer (MTC) remains a therapeutic challenge. The multi-tyrosine kinase inhibitors (TKIs) vandetanib and cabozantinib have been approved for the treatment of progressive MTC based on prolonged progression-free survival (PFS) in phase 3 clinical trials. Patients and Methods: To evaluate clinical characteristics, treatment regimens, efficacy, and treatment emergent adverse events (TEAEs) of vandetanib and cabozantinib in MTC patients outside clinical trials at four German tertiary care centers. Forty-eight patients diagnosed between 1990 and 2018 were included. PFS and overall survival (OS) probabilities were estimated using the Kaplan-Meier method and compared by log-rank test. Results: The median age at diagnosis was 46 years (15-80 years); a germ line RET (rearranged during transfection) mutation was known in 6 (13%) patients. Thirty-two (67%) patients showed progressive disease before TKI initiation. Forty-seven (98%) patients were treated with vandetanib and 23 (48%) patients with cabozantinib. Vandetanib was first-line treatment in 41 (85%) patients and cabozantinib in 7 (15%) patients. Partial response was the best response in 12 (26%) patients treated with vandetanib and in 5 (22%) patients treated with cabozantinib. Sixteen (34%) patients treated with vandetanib and 3 (13%) patients treated with cabozantinib had stable disease ≥24 weeks. The median PFS for vandetanib and cabozantinib was 17 months [95% confidence interval, CI, 9.3-24.6 months] and 4 months [CI 3.1-4.9 months], respectively. The 6- and 12-month survival rates were 98% and 86% for vandetanib and 78% and 70% for cabozantinib, respectively. The median OS for vandetanib and cabozantinib was 53 months [CI 43.7-62.3 months] and 24 months [CI 5.9-42.1 months], respectively. In vandetanib-treated patients, the PFS and OS were significantly longer in patients aged ≤60 years at TKI initiation and in patients with ≥5 TEAEs. Additionally, the PFS was longer in the absence of bone metastases. In cabozantinib-treated patients, the PFS was significantly longer in patients experiencing TEAEs and in patients aged ≤60 years, and the OS was significantly longer in patients who had TEAEs and in patients with ≥5 TEAEs. Conclusions: Vandetanib and cabozantinib are effective treatment options in the majority of MTC patients. We hypothesize that the poorer prognosis of cabozantinib-treated patients in our retrospective analysis is most likely due to its use as second-line treatment after treatment failure on vandetanib. However, different degrees of efficacy of the two drugs are possible.

Genomics and Epigenomics of Medullary Thyroid Carcinoma: From Sporadic Disease to Familial Manifestations

Our understanding of the genomics and epigenomics of medullary thyroid carcinoma (MTC) has advanced since the initial recognition of RET as a driver of MTC tumorigenesis in familial MTC. We now have insight into the frequency and prognostic significance of specific RET mutations in sporadic MTC. For example, the most common RET mutation in sporadic MTC is the RET Met918Thr mutation, the same mutation that underlies MEN2B and a poor prognosticator. This mutation is relatively infrequent in medullary thyroid microcarcinomas but is over-represented in advanced-stage disease. RAS mutations are detected in 70% of sporadic, RET wild-type MTC. Although next-generation and whole-exome sequencing studies have shown that tumors that are wild-type for RET and RAS mutations essentially lack other recurrent mutations, additional pathways and epigenetic alterations have been implicated in MTC tumorigenesis. Increased insight into the clinical course of patients with familial MTC with specific RET mutations has guided treatment recommendations for these patients. Finally, an understanding of the genomics has informed treatment for patients with advanced MTC. In this review, we will examine the genomics and epigenomics of sporadic and familial MTC, along with the prognostic significance of molecular alterations, management of patients with germline RET mutations, and treatment strategies for MTC patients.

A Narrative Review of Genetic Alterations in Primary Thyroid Epithelial Cancer

Thyroid carcinoma is the most frequent endocrine neoplasia. Different types of thyroid carcinoma are described: well-differentiated papillary thyroid carcinoma (PTC), poorly differentiated thyroid carcinoma (PDTC), follicular thyroid carcinoma (FTC), anaplastic thyroid carcinoma (ATC), and medullary thyroid carcinoma (MTC). MTC is inherited as an autosomal dominant trait in 25% of cases. The genetic landscape of thyroid carcinoma has been largely deciphered. In PTC, genetic alterations have been found in about 95% of tumors: BRAF mutations and RET rearrangements are the main genetic alterations. BRAF and RAS mutations have been confirmed to play an important role also in PDTC and ATC, together with TP53 mutations that are fundamental in tumor progression. It has also been clearly demonstrated that telomerase reverse transcriptase (TERT) promoter mutations and TP53 mutations are present with a high-frequency in more advanced tumors, frequently associated with other mutations, and their presence, especially if simultaneous, is a signature of aggressiveness. In MTC, next-generation sequencing confirmed that mutations in the RET gene are the most common molecular events followed by H-RAS and K-RAS mutations. The comprehensive knowledge of the genetic events responsible for thyroid tumorigenesis is important to better predict the biological behavior and better plan the therapeutic strategy for specific treatment of the malignancy based on its molecular profile.

RET mutated C-cells proliferate more rapidly than non-mutated neoplastic cells

A statistically significant higher prevalence of the RET p.Met918Thr somatic mutation, identified by direct sequencing, was previously reported in MTC > 2 cm than in smaller tumors. Aim of this study was to correlate the full RET and RAS mutation profile, identified by a Next Generation Sequencing approach, with the growth rate, proliferation and tumor size of MTC. Data of 149 sporadic MTC patients were correlated with RET mutations and Ki67 positivity. Eighty-one cases had a somatic RET mutation, 40 had a RAS mutation and 28 were negative. A statistically significant higher prevalence of RET mutations was found in MTC > 2 cm. A higher prevalence of RET more aggressive mutations, higher allelic frequencies and, higher percentage of Ki67 positive cells were found in larger tumors which had also a worse outcome. Our study highlights the predominant role of RET somatic mutations in MTC tumorigenesis. We demonstrate that RET mutation prevalence and allelic frequency (AF) are significantly higher in larger tumors. Based on these results, we can conclude that RET mutated C-cells's growth and proliferation are more rapid than those of non-mutated cells and give origin to bigger and more aggressive MTC.

Update on Targeted Therapy in Medullary Thyroid Cancer

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor that accounts for 2-4% of all thyroid cancers. All inherited MTC and approximately 50% of sporadic cases are driven by mutations in the REarranged during Transfection (RET) proto-oncogene. The recent expansion of the armamentarium of RET-targeting tyrosine kinase inhibitors (TKIs) has provided effective options for systemic therapy for patients with metastatic and progressive disease. However, patients that develop resistant disease as well as those with other molecular drivers such as RAS have limited options. An improved understanding of mechanisms of resistance to TKIs as well as identification of novel therapeutic targets is needed to improve outcomes for patients with MTC.

Impact of Advanced Age on the Clinical Presentation and Outcome of Sporadic Medullary Thyroid Carcinoma

Simple Summary

The clinical behavior of medullary thyroid carcinoma is heterogeneous and can be influenced by several clinical, biochemical and molecular factors. The role of age as a prognostic factor remains controversial. In our cohort of 432 sporadic medullary thyroid carcinoma, no differences in histologic features at diagnosis and in number and type of therapies performed during the follow-up were detected when dividing the patients according to age (< and ≥ 65 years). Younger patients had a longer follow-up and survival time, compared to the older patients. However, in dead patients, no differences in the aggressiveness of the disease at presentation and treatments performed during the follow-up were found between the two age groups.

Abstract

Sporadic medullary thyroid carcinoma (MTC) is a rare malignancy with a heterogeneous clinical course. Several potential prognostic factors have been investigated, but the impact of some of these is controversial, such as age at diagnosis. We evaluated the data of 432 sporadic MTC patients followed-up for a median of 7.4 years. Patients were divided and compared according to their age at diagnosis in group A (<65 years—n = 338, 78.2%) and group B (≥65 years—n = 94, 21.8%). No differences were detected between the two groups. Median follow-up time was significantly longer in patients <65 than ≥65 years. We observed 41 (9.5%) cancer-related death events. The death rate was similar between the two age groups. However, the Kaplan Meier curve showed a longer survival time for younger patients compared to older patients [HR 2.5 (CI 95%: 1.27–4.94), p < 0.01]. Nevertheless, no differences in the aggressiveness of the disease at presentation and in the number and type of treatments performed were found in the two subgroups of dead patients. In patients with sporadic MTC, age at diagnosis did not correlate with any clinical and pathological features. Cancer-related death events are similar in older and younger patients, but survival time is longer in the younger.

Current status of the prognostic molecular markers in medullary thyroid carcinoma

Medullary thyroid cancer (MTC) is a rare thyroid malignancy, which arises from parafollicular C-cells. It occurs in the hereditary or sporadic form. Hereditary type is a consequence of activation of the RET proto-oncogene by germline mutations, whereas about 80% of sporadic MTC tumors harbor somatic, mainly RET or rarely RAS mutations. According to the current ATA guidelines, a postoperative MTC risk stratification and long-term follow-up are mainly based on histopathological data, including tumor stage, the presence of lymph node and/or distant metastases (TNM classification), and serum concentration of two biomarkers: calcitonin (Ctn) and carcinoembryonic antigen (CEA). The type of RET germline mutation also correlates with MTC clinical characteristics. The most common and the best known RET mutation in sporadic MTC, localized at codon 918, is related to a more aggressive MTC course and poorer survival. However, even if histopathological or clinical features allow to predict a long-term prognosis, they are not sufficient to select the patients showing aggressive MTC courses requiring immediate treatment or those, who are refractory to different therapeutic methods. Besides the RET gene mutations, there are currently no other reliable molecular prognostic markers. This review summarizes the present data of genomic investigation on molecular prognostic factors in medullary thyroid cancer.

A Proposed Grading Scheme for Medullary Thyroid Carcinoma Based on Proliferative Activity (Ki-67 and Mitotic Count) and Coagulative Necrosis

We investigated the prognostic value of a range of histologic parameters in medullary thyroid carcinoma (MTC) to design a grading system to predict overall survival. We assessed 76 patients with MTCs undergoing primary tumor resection for age, sex, tumor size, vascular space invasion, lymph node metastasis, multiple endocrine neoplasia type 2 (MEN2) status, mitotic count, Ki-67 proliferative index, spindled morphology, sheet-like growth pattern, coagulative necrosis, incipient necrosis, nuclear grade, multinucleation, prominent nucleoli, fibrosis, and amyloid deposition. In addition to the clinical features of age and the diagnosis of MEN2, the only histologic features that significantly predicted reduced overall survival were Ki-67 proliferative index, mitotic count, and the presence of coagulative necrosis. Using a combination of these 3 variables, we propose a 3-tiered grading system based solely on proliferative activity (Ki-67 proliferative index and mitotic count) and necrosis. There were 62 (82%) low-grade MTCs (low proliferative activity, no necrosis), 9 (12%) intermediate grade (low proliferative activity and necrosis present, or intermediate proliferative activity and no necrosis), and 5 (7%) high grade (intermediate proliferative activity and necrosis present, or high proliferative activity with or without necrosis). The mean overall survival was 193, 146, and 45 months, respectively (P=0.0001) for the 3 grades. The grading system remained prognostic when controlled for other factors associated with survival including age and known MEN2 syndrome. We conclude that this proposed grading system, which uses only a combination of proliferative activity (Ki-67 index, mitotic count) and coagulative necrosis, is a strong predictor of overall survival in MTC.

CD133 Expression in Medullary Thyroid Cancer Cells Identifies Patients with Poor Prognosis

CONTEXT

The identification of markers able to determine medullary thyroid cancer (MTC) patients at high-risk of disease progression is critical to improve their clinical management and outcome. Previous studies have suggested that expression of the stem cell marker CD133 is associated with MTC aggressiveness.

OBJECTIVE

To evaluate CD133 impact on disease progression in MTC and explore the regulatory mechanisms leading to the upregulation of this protein in aggressive tumors.

PATIENTS

We compiled a series of 74 MTCs with associated clinical data and characterized them for mutations in RET and RAS proto-oncogenes, presumed to be related with disease clinical behavior.

RESULTS

We found that CD133 immunohistochemical expression was associated with adverse clinicopathological features and predicted a reduction in time to disease progression even when only RET-mutated cases were considered in the analysis (log-rank test P < 0.003). Univariate analysis for progression-free survival revealed CD133 expression and presence of tumor emboli in peritumoral blood vessels as the most significant prognostic covariates among others such as age, gender, and prognostic stage. Multivariate analysis identified both variables as independent factors of poor prognosis (hazard ratio = 16.6 and 2; P = 0.001 and 0.010, respectively). Finally, we defined hsa-miR-30a-5p, a miRNA downregulated in aggressive MTCs, as a CD133 expression regulator. Ectopic expression of hsa-miR-30a-5p in MZ-CRC-1 (RETM918T) cells significantly reduced CD133 mRNA expression.

CONCLUSIONS

Our results suggest that CD133 expression may be a useful tool to identify MTC patients with poor prognosis, who may benefit from a more extensive primary surgical management and follow-up.

Medullary Thyroid Cancer in Patients Older than 45-Epidemiologic Trends and Predictors of Survival

Simple Summary

Sporadic medullary thyroid cancer can occur anytime in life although they tend to present at a later age (≥45 years old) when the tumors are more easily discernible or become symptomatic. We present, in this study, a group of patients diagnosed with medullary thyroid cancer at or after 45 years of age when they are more likely to develop sporadic forms of medullary thyroid cancer with regard to their natural history and prognosis. In this study, we evaluated factors affecting survival in such patients. We found that the incidence of medullary thyroid cancer in patients ≥45 years of age is increasing. Our findings suggest that patients should be offered surgical resection at an early stage to improve their outcomes.

Abstract

Sporadic medullary thyroid cancer (MTC) can occur anytime in life although they tend to present at a later age (≥45 years old) when the tumors are more easily discernible or become symptomatic. We aimed to identify the factors affecting the survival in patients ≥45 years of age diagnosed with MTC. We analyzed the Surveillance, Epidemiology, and End Results (SEER) registry from 1973–2016 focusing on patients ≥45 years of age with MTC as an isolated primary. A total of 2533 patients aged ≥45 years with MTC were identified. There has been a statistically significant increase of 1.19% per year in the incidence of MTC for this group of patients. The disease was more common in females and the Caucasian population. Most patients had localized disease on presentation (47.6%). Increasing age and advanced stage of presentation were associated with worse survival with HR 1.05 (p < 0.001) and HR 3.68 (p < 0.001), respectively. Female sex and surgical resection were associated with improved survival with HR 0.74 (p < 0.001) and 0.36 (p < 0.001), respectively. In conclusion, the incidence of MTC in patients ≥45 years of age is increasing. Patients should be offered surgical resection at an early stage to improve their outcomes.

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.

Analytical and clinical validation of pairwise microRNA expression analysis to identify medullary thyroid cancer in thyroid fine-needle aspiration samples

Background

Medullary thyroid carcinoma (MTC) is an aggressive malignancy originating from the parafollicular C cells. Preoperatively, thyroid nodule fine‐needle aspiration cytology (FNAC) and pathogenic gene mutations are definitive in approximately one‐half of cases. MicroRNAs (miRNAs) are endogenous, noncoding, single‐stranded RNAs that regulate gene expression, a characteristic that confers the potential for identifying malignancy. In the current study, the authors hypothesized that differential pairwise (diff‐pair) analysis of miRNA expression levels would reliably identify MTC in FNA samples.

Methods

The relative abundance of 10 different miRNAs in total nucleic acids was obtained from ThyraMIR test results. Diff‐pair analysis was performed by subtracting the critical threshold value of one miRNA from the critical threshold values of other miRNAs. Next‐generation sequencing with the ThyGeNEXT panel identified oncogenic gene alterations. The discovery cohort consisted of 30 formalin‐fixed, paraffin‐embedded benign and malignant thyroid neoplasms, including 4 cases of MTC. After analytical validation, clinical validation was performed using 3 distinct cohorts (total of 7557 specimens).

Results

In the discovery cohort, 9 diff‐pairs were identified as having significant power using the Kruskal‐Wallis test (P < .0001) to distinguish MTC samples from non‐MTC samples. The assay correctly classified all MTC and non‐MTC samples in the analytical validation study and in the 3 clinical validation cohorts. The overall test accuracy was 100% (95% confidence interval, 99%‐100%). In indeterminate FNAC samples, the sensitivity of the diff‐pair analysis was greater than that of the MTC‐specific mutation analysis (100% vs 25%; P = .03).

Conclusions

Pairwise miRNA expression analysis of ThyraMIR results were found to accurately predict MTC in thyroid FNA samples, including those with indeterminate FNAC findings.

The authors have developed and validated a microRNA (miRNA) test for the detection of medullary thyroid cancer (MTC) in preoperative thyroid nodule samples. The method, based on differential pairwise analysis of miRNA expression data generated using the ThyraMIR Thyroid miRNA Classifier, accurately predicts MTC with 100% sensitivity and 100% specificity in thyroid fine‐needle aspiration biopsies.

Updates in the advances of sporadic medullary thyroid carcinoma: from the molecules to the clinic

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignancy that originates in parafollicular cells. It is well-known that a quarter of MTC are involved in hereditary multiple endocrine neoplasia type 2 syndromes, whereas most MTC are sporadic. Unlike the commonly encountered gastrointestinal or pulmonary neuroendocrine tumors, most sporadic MTCs have distinct genetic alterations featured by somatic changes of either Rearranged during Transfection (RET) or RAS point mutation. The increasing application of next-generation sequencing, whole-exome sequencing, and other molecular detection techniques enables us to understand MTC comprehensively concerning its detailed molecular changes and their clinical correlations. This article reviews the advances in genetic alterations and their prognostic impact in sporadic MTC among different populations and discusses the associated tumor immune microenvironments and the potential role of immunotherapy targeting PD-L1/PD-1 in treating MTC. Furthermore, the current multikinase inhibitor targeting therapy for sporadic MTC has been summarized here and its efficacy and drug toxicity are discussed. Updates in advance of the role of calcitonin/procalcitonin/calcitonin-related polypeptide alpha (CALCA) gene transcripts in diagnosing and handling MTC are also mentioned. The treatment of advanced MTC is still challenging and might require a combination of several modalities.

Association between age and disease specific mortality in medullary thyroid cancer

BACKGROUND

The aim of this study was to evaluate the association between age and disease specific mortality (DSM) among adults diagnosed with medullary thyroid cancer (MTC).

METHOD

Surveillance, Epidemiology, and End Results (SEER-18) was used to analyze adult MTC patients stratified by age (18-64, 65-79, ≥80 years). Associations between patient demographics, tumor size, nodal status, metastatic disease, and extent of surgery on DSM was assessed with multivariable Cox regression.

RESULTS

Among 1457 patients with MTC, 1008 (69.2%) were younger adults, 371 (25.5%) older adults, and 78 (5.4%) were super-elderly. A significantly higher proportion of older adults and super-elderly had less than the recommended operation for MTC. On multivariable analysis, older adults and super-elderly were 2.9 and 6.7 times more likely to have an increased DSM (HR:2.91, 95% CI: 1.83-4.63; p < 0.001 and HR: 6.70, 95%CI: 3.69-12.20; p < 0.001). Extent of surgery or lymphadenectomy did not affect DSM.

CONCLUSIONS

Increased age is an independent predictor of DSM in patients with MTC.

Clinical and Translational Challenges in Thyroid Cancer

Thyroid cancer is the most common endocrine malignancy and it accounts for 1% of all newly diagnosed tumors. Approximately 10% of patients with differentiated thyroid carcinomas (DTC) and 30% with medullary thyroid carcinoma (MTC) could not be cured with locoregional treatment and could develop metastatic disease. In addition, one of the most aggressive solid tumors can arise from the thyroid gland, the anaplastic thyroid carcinoma, with a median overall survival of less than 6 months. Currently, only four drugs are approved for the treatment of DTC and MTC and several unmet needs are focusing the scientific discussions, including the resistant setting, the off-target side effects that may reduce the efficacy and the molecular knowledge-based combinations. In this review, we aimed to discuss the current molecular landscape and treatment of thyroid cancers, and the ongoing clinical and translational research lines focusing on new drugs and drug combinations to improve the inhibition of driver mutations, such as BRAF and RET, and how systemic therapies that improved outcomes of other cancer types, like immunotherapy and peptide receptor radionuclide therapy, may play a role in the future management of advanced thyroid cancers.

Grading of medullary thyroid carcinoma on the basis of tumor necrosis and high mitotic rate is an independent predictor of poor outcome

Medullary thyroid carcinoma (MTC) is a rare nonfollicular cell-derived tumor. A robust grading system may help better stratify patients at risk for recurrence and death from disease. In total, 144 MTC between 1988 and 2018 were subjected to a detailed histopathologic evaluation. Clinical and pathologic data were correlated with disease specific survival (DSS), local recurrence free survival (LRFS)  and distant metastasis free survival (DMFS). Median age was 53 years (range: 3-88). Median tumor size was 1.8 cm (range: 0.2-11). Lymph node metastases were present in 84 (58%) cases while distant metastases at presentation were found in 9 (6%) patients. Seven (5%) had ≥5 mitoses/10 HPFs. Tumor necrosis was present in 30 cases (20%) while lymphovascular invasion occurred in 41 (28%) of tumors. Extra-thyroidal extension was found in 44 (31%) and positive margins were seen in 19 (14%). There was a strong correlation between increasing tumor size and tumor necrosis (p < 0.001). Median follow up was 39 months. In univariate analysis, male gender, higher American Joint Committee on Cancer (AJCC) stage group, larger tumor size, tumor necrosis, high mitotic index (≥5/10 HPF), nodal status, size of largest nodal metastasis, and elevated postoperative serum calcitonin predicted worse DSS, LRFS, and DMFS (p < 0.05). Extra-thyroidal extension correlated with DSS and DMFS while positive margins and distant metastasis at presentation imparted worse DSS (p < 0.05). In multivariate analysis, tumor necrosis and mitotic activity (5 mitosis/10 HPFs as the cutoff) were the only independent predictors for DSS (p = 0.008 and 0.026, respectively). Tumor necrosis was the sole independent prognostic factor for LRFS and DMFS (p = 0.001 and 0.003, respectively). The presence of tumor necrosis and high mitotic rate are powerful independent prognostic factors in MTC and outperform serum calcitonin and stage. We propose a grading system based on tumor necrosis and mitotic activity to better stratify MTC patients for counseling, post-resection surveillance, and therapy.

Comparison of pediatric and adult medullary thyroid carcinoma based on SEER program

To compare the clinicopathological characteristics and survival outcomes of children and adult diagnosed with medullary thyroid carcinoma (MTC). MTC patients were extracted from the Surveillance, Epidemiology and End Results (SEER) database from 1998 to 2016, followed by stratification into pediatric (< 20 years) or adult (≥ 20 years) groups. In total, 2,197 patients (110 pediatric and 2087 adult) with MTC were identified. Pediatric patients were more likely to have localized stage (70.0% vs. 51.6%), negative regional nodes (48.2% vs. 30.8%) and receive total/subtotal thyroidectomy surgery (97.3% vs. 85.3%). Moreover, CSS and OS rates were significantly higher in pediatric patients (both P < 0.001). Multivariable Cox regression analysis revealed that adult patients were significantly correlated with worse CSS and OS rates [(CSS: HR 11.60, 95% CI 1.62–83.02, P = 0.015); (OS: HR 5.63, 95% CI 2.08–15.25, P = 0.001)]. Further stratified analysis indicated that pediatric group might have significant better CSS and OS for patients with more advanced stage. Patients in the pediatric group were more likely to have earlier stage. Moreover, the prognosis of pediatric MTC patients was significantly better than that in adult patients.

Current and Future Role of Tyrosine Kinases Inhibition in Thyroid Cancer: From Biology to Therapy

Thyroid cancer represents a heterogenous disease whose incidence has increased in the last decades. Although three main different subtypes have been described, molecular characterization is progressively being included in the diagnostic and therapeutic algorithm of these patients. In fact, thyroid cancer is a landmark in the oncological approach to solid tumors as it harbors key genetic alterations driving tumor progression that have been demonstrated to be potential actionable targets. Within this promising and rapid changing scenario, current efforts are directed to improve tumor characterization for an accurate guidance in the therapeutic management. In this sense, it is strongly recommended to perform tissue genotyping to patients that are going to be considered for systemic therapy in order to select the adequate treatment, according to recent clinical trials data. Overall, the aim of this article is to provide a comprehensive review on the molecular biology of thyroid cancer focusing on the key role of tyrosine kinases. Additionally, from a clinical point of view, we provide a thorough perspective, current and future, in the treatment landscape of this tumor.

Genomic and Transcriptomic Characterization of Sporadic Medullary Thyroid Carcinoma

Background: Sporadic medullary thyroid carcinoma (MTC) is a relatively uncommon neuroendocrine malignancy and the molecular tumorigenesis of its sporadic type (sMTC) is only partially understood. In this study, we performed a study focusing on the genomic and transcriptomic characterization of sMTC. Methods: Twenty-nine sMTC patients were included. Whole-exome sequencing (WES) was carried out in 18 patients, including both tumor samples and matched noncancerous tissues. Whole transcriptome sequencing (RNA-Seq) was performed in all 29 tumors. WES, RNA-Seq, and copy number alteration (CNA) data were analyzed. A Cell Counting Kit-8 (CCK-8) assay was used to evaluate cell proliferation. Results: Among the somatic mutations, RET was the only recurrently cancer-related mutated gene (5/18, 27.8%). In the germline, FAT1 and FAT4, two members of the FAT gene family, were identified as the two most common mutated genes. CNA analysis found that FAT1 and FAT4, both located on chromosome 4q, were also two of the genes most commonly affected by somatic chromosomal deletions (4/18, 22.2%). Using TT and MZ-CRC-1 cell lines, the CCK-8 assay showed that FAT1 and FAT4 knockdown could promote MTC cell proliferation. Based on the gene expression profile, patients were clustered into two molecular subtypes: the mesenchymal-like subtype is characterized by epithelial-mesenchymal transition, while the proliferative-like subtype is associated with enrichment of cell cycle pathways. Most events of structural recurrence (80%) occurred in the proliferative-like subtype. Conclusion: In addition to RET, these findings demonstrate that FAT1/FAT4 genomic alterations appear to be frequent in sMTC. Two molecular subtypes of sMTC with distinct biological behavior could be identified. However, these results need to be validated by larger samples and more comprehensive experiments in the future, especially for the frequency and function of FAT1/FAT4 germline variants.

Efficacy and Safety of Vandetanib in Progressive and Symptomatic Medullary Thyroid Cancer: Post Hoc Analysis From the ZETA Trial

PURPOSE

We conducted a post hoc analysis of the vandetanib phase III trial involving patients with advanced medullary thyroid cancer (MTC) to assess the efficacy and safety of vandetanib in patients with progressive and symptomatic MTC. The primary objective of the analysis was to determine progression-free survival (PFS) of these patients.

PATIENTS AND METHODS

Eligible patients from the ZETA trial were divided into 4 disease severity subgroups: progression and symptoms, symptoms only, progression only, and no progression and no symptoms assessed at baseline. PFS, determined from objective tumor measurements performed by the local investigator, overall survival (OS), time to worsening of pain (TWP), and objective response rate (ORR) were evaluated.

RESULTS

Of the 331 patients in this trial, 184 had symptomatic and progressive disease at baseline. In this subgroup, results were similar in magnitude to those observed in the overall trial for PFS (hazard ratio [HR], 0.43; 95% CI, 0.28 to 0.64; P < .0001), OS (HR, 1.08; 95% CI, 0.72 to 1.61; P = .71), and TWP (HR, 0.67; 95% CI, 0.43 to 1.04; P = .07), and the observed adverse events were consistent with the known safety profile of vandetanib. In this subgroup, the ORR was 37% in the treatment arm versus 2% in the placebo arm.

CONCLUSION

Vandetanib demonstrated clinical benefit—specifically, increased PFS—in patients with symptomatic and progressive MTC.

Genetic screening for monogenic hypertension in hypertensive individuals in a clinical setting

BACKGROUND

Monogenic hypertension describe a series of hypertensive syndromes that are inherited by Mendelian laws. Sometimes genetic testing is required to provide evidence for their diagnoses, precise classification and targeted treatment. This study is the first to investigate the clinical utility of a causative gene screening and the combined yield of gene product expression analyses in cases with suspected monogenic hypertension.

METHODS

We performed a large-scale multi-centre clinical genetic research of 1179 expertly selected hypertensive individuals from the Chinese Han population. Targeted sequencing were performed to evaluate 37 causative genes of potential cases of monogenic hypertension. Pathogenic and likely pathogenic variants were classified using the American College of Medical Genetics guidelines. Additionally, 49 variants of unknown significance (VUS) that had relatively high pathogenicity were selected and analysed using immunoblot protein expression assays.

RESULTS

21 pathogenic or likely pathogenic variants were identified in 33 of 1179 cases (2.80%). Gene product expression analyses showed 27 VUSs harboured by 49 individuals (4.16%) could lead to abnormally expressed protein levels. Consequently, combining genetic screening with gene product expression analyses increased the diagnostic yield from 2.80% to 6.79%. The main aetiologies established were primary aldosteronism (PA; 27, 2.29%) and pheochromocytoma and paraganglioma (PPGL; 10, 0.85%).

CONCLUSION

Molecular diagnoses obtained using causative gene screening combined with gene product expression analyses initially achieved a modest diagnostic yield. Our data highlight the predominant roles of PA and PPGL. Furthermore, we provide evidence indicating the enhanced diagnostic ability of combined genetic and functional evaluation.

Medullary Thyroid Cancer - Feature Review and Update on Systemic Treatment

Medullary thyroid carcinoma (MTC) is a rare malignancy that originates from parafollicular (C cells) of the thyroid and accounts for 2-4% of all thyroid malignancies. MTC may be sporadic or inherited, the latter as part of the MEN 2 syndromes. Germline mutations in the RET proto-oncogene (REarranged during Transfection) are driver mutations in hereditary MTC, whereas somatic RET mutations and, less frequently, RAS mutations, have been described in tumor tissues of sporadic MTC. Genetic screening for germline mutations in RET proto-oncogene identifies gene carriers of germline mutations. That enables primary prevention (the avoidance of disease onset by total prophylactic thyroidectomy), or at least secondary prevention (early detection) of the disease. Radical surgery with complete tumor resection is still pivotal in attaining cure for MTC. Despite recent advances, the treatment of advanced, metastatic, and progressive MTC remains challenging. Metastatic MTC can have an indolent clinical course; therefore, it is necessary to assess which patient to cure and when to initiate the treatment. Multidisciplinary boards of various specialists involved in the diagnostics and therapy of the patients with MTC in highly specialized centers with a high volume of patients provide optimal patient management. Multikinase inhibitors (MKI) vandetanib and cabozantinib were approved for the treatment of progressive or symptomatic metastatic/unresectable MTC. Although these treatments have been shown to improve progression-free survival (PFS) with higher overall response rates (ORR) compared with placebo, no MKI has been shown to increase the overall survival (OS) yet, except in the subgroup of patients with RETM918T-mutations on cabozantinib therapy. As these drugs are nonselective, significant off-target toxicities may occur. Recently, next-generation small-molecule tyrosine kinase inhibitors (TKIs) have been developed. These highly selective RET-inhibitors are specifically designed for highly potent and selective targeting of oncogenic RET alterations, making them promising drugs for the treatment of advanced MTC. The selective RET-inhibitor selpercatinib has been very recently registered for the treatment of RET-mutated thyroid cancer.

Impact of multikinase inhibitor approval on survival and physician practice patterns in advanced or metastatic medullary thyroid carcinoma

BACKGROUND

This study aimed to identify whether multikinase inhibitor approval for medullary thyroid carcinoma was associated with changes in systemic therapy administration or overall survival.

METHODS

The National Cancer Database was queried for advanced medullary thyroid carcinoma patients. Clinicopathologic comparisons were performed between premultikinase inhibitor (2005-2010) and postmultikinase inhibitor (2011-2016) approval groups. Multivariable logistic and Cox regressions were applied to assess predictors of systemic therapy and overall survival.

RESULTS

A total of 2,891 patients met the criteria. Postmultikinase inhibitor patients were less likely to undergo radiation (P = .02) and more likely to receive systemic therapy (P = .01). The rate of systemic therapy nearly doubled from 2010 to 2011 (8.1% to 13.8%, P = .04); it subsequently declined back toward preapproval rates. Before multikinase inhibitor approval, only metastases and radiation were associated with systemic therapy (P < .05). After multikinase inhibitor approval, patients with small tumors, extrathyroidal extension, positive lymph nodes, or metastases were more likely to receive systemic therapy (P < .05). The 5-year overall survival between pre and postmultikinase inhibitor groups, for those who received systemic therapy (n = 288), was similar (P = .58), even when restricted to patients with distant metastases (P = .55).

CONCLUSION

After approval of multikinase inhibitors, physicians broadened the criteria for systemic therapy. Prescription rates have since declined. Given the toxicities of these drugs and no improvement in overall survival since introduction, selective utilization may be warranted.

YAP confers resistance to vandetanib in medullary thyroid cancer

Medullary thyroid cancer (MTC) is the third most common thyroid cancer. RET (Rearranged in Transformation) gene mutations are considered as one of the major drivers of MTC. Vandetanib suppresses RET activity, and has shown promise in clinical trials. Unfortunately, acquired resistance to vandetanib has been observed in MTC, although the mechanism was largely unknown. We investigated the critical role of YAP (Yes-Associated Protein) on vandetanib resistance in MTC. For this, TT cells (medullary thyroid cancer cells) were treated with vandetanib for 3 months to generate a vandetanib-resistant cell line (TT-R). We investigated the role of YAP on vandetanib-resistance in TT-R cells by performing cell proliferation and colony formation assays, and examined the antitumor effects of YAP inhibitor and vandetanib in a mouse model of xenografted MTC. The TT-R cells displayed 6-fold higher IC₅₀ to vandetanib than the TT cells. Overexpression of YAP resulted in resistance to vandetanib, whereas knockdown of YAP re-sensitized the TT-R cells to vandetanib. The YAP inhibitor synergized with vandetanib on tumor inhibition. Our results suggest that YAP plays an important role in acquired resistance to vandetanib in MTC, providing basis for combating MTC with YAP inhibitor and vandetanib.

Identifying novel oncogenic RET mutations and characterising their sensitivity to RET-specific inhibitors

BACKGROUND

Rearranged during transfection (RET) is a well-known proto-oncogene. Multiple RET oncogenic alterations have been identified, including fusions and mutations. Although RET fusions have been reported in multiple cancers, RET mutations were mainly found in multiple endocrine neoplasia type 2 and medullary thyroid carcinoma. RET mutations in other cancers were underinvestigated and their functional annotation was less well studied.

METHODS

We retrospectively reviewed next-generation sequencing data from 37 056 patients with cancer to search for RET mutations. We excluded patients with other co-occurring known driver mutations to enrich potential activating RET mutations for further analysis. Moreover, we performed in vitro functional validation of the oncogenic property of several high frequent and novel RET mutants and their sensitivity to RET-specific inhibitors LOXO-292 and BLU-667.

RESULTS

Within 560 (1.5%) patients with cancer who harbour RET mutations, we identified 380 distinct RET mutation sites, including 252 sites without co-occurring driver mutations. RET mutations were more frequently found in thyroid cancer, mediastinal tumour and several other cancers. The mutation sites spread out through the whole protein with a few hotspots within the kinase domain. In addition, we functionally validated that 898-901del, T930P and T930K were novel RET-activating mutations and they were all sensitive to RET inhibitors.

CONCLUSION

Our results demonstrated the frequency of RET mutations across different cancers. We reported and/or validated several previously uncharacterised RET oncogenic mutations and demonstrated their sensitivity to RET-specific inhibitors. Our results help to stratify patients with cancer based on their RET mutation status and potentially provide more targeted treatment options.

Toward a More Precise Future for Oncology

Prospective molecular characterization of cancer has enabled physicians to define the genomic changes of each patient's tumor in real time and select personalized therapies based on these detailed portraits. Despite the promise of such an approach, previously unrecognized biological and therapeutic complexity is emerging. Here, we synthesize lessons learned and discuss the steps required to extend the benefits of genome-driven oncology, including proposing strategies for improved drug design, more nuanced patient selection, and optimized use of available therapies. Finally, we suggest ways that next-generation genome-driven clinical trials can evolve to accelerate our understanding of cancer biology and improve patient outcomes.