Advances in thyroid cancer treatment: latest evidence and clinical potential

Personalized Medicine in Medullary Thyroid Carcinoma: A Broad Review of Emerging Treatments

Medullary thyroid carcinoma (MTC) arises from parafollicular cells in the thyroid gland, and although rare, it represents an aggressive type of thyroid cancer. MTC is recognized for its low mutational burden, with point mutations in RET or RAS genes being the most common oncogenic events. MTC can be resistant to cytotoxic chemotherapy, and multitarget kinase inhibitors (MKIs) have been considered a treatment option. They act by inhibiting the activities of specific tyrosine kinase receptors involved in tumor growth and angiogenesis. Several tyrosine kinase inhibitors are approved in the treatment of advanced MTC, including vandetanib and cabozantinib. However, due to the significant number of adverse events, debatable efficiency and resistance, there is a need for novel RET-specific TKIs. Newer RET-specific TKIs are expected to overcome previous limitations and improve patient outcomes. Herein, we aim to review MTC signaling pathways, the most recent options for treatment and the applications for personalized medicine.

Flurbiprofen inhibits cell proliferation in thyroid cancer through interrupting HIP1R-induced endocytosis of PTEN

Background

The incidence of thyroid cancer, a most common tumor in the endocrine system, has increased in recent years. A growing number of studies have focused on the molecular mechanisms of thyroid cancer subtypes, aiming to identify effective therapeutic targets. Endocytosis is of vital significance in the malignant development of tumors, although its involvement in thyroid cancer has been rarely reported.

Methods

HIP1R expressions in thyroid cancer from the TCGA database were analyzed by UALCAN software. Thyroid epithelial and cancer cell lines were cultured in vitro. Western blotting and quantitative PCR were used to analyze protein and mRNA levels, respectively. Cell viability was measured by CCK-8 assay. Immunofluorescence staining indicated protein distribution in cell. Co-immunoprecipitation was used to study protein–protein interaction. Immunohistochemical staining was used to analyze protein expression in clinical tissues. Differences between groups were compared using the two-tailed Student’s t test, and those among three or more groups were compared by one-way or two-way ANOVA.

Results

In the present study, HIP1R (Huntingtin Interacting Protein 1 Related) was found upregulated in thyroid cancer tissues and cell lines compared with that in the controls, while knockdown of HIP1R significantly inhibited the proliferation of thyroid cancer cells. Since HIP1R is essential for the clathrin-dependent endocytic process, we thereafter explored the effect of HIP1R on the endocytosis of thyroid cancer cells. Interestingly, knockdown of HIP1R significantly reduced the number of clathrin-coated pits (CCPs) in thyroid cancer cells. In addition, the interaction between HIP1R and PTEN (phosphatase and tensin homolog) was identified in thyroid cancer cells. Knockdown of HIP1R downregulated intracellular PTEN in thyroid cancer cells, but upregulated membrane-binding PTEN. Notably, flurbiprofen, a commonly used analgesic, significantly inhibited the proliferation of thyroid cancer cells and interfered with the interaction between HIP1R and PTEN, thereby enhancing the binding of PTEN to cell membrane. However, the proliferation inhibitory effect of flurbiprofen was attenuated when knocking down HIP1R or PTEN.

Conclusions

Upregulated HIP1R in thyroid cancer cells promotes cell proliferation and mediates the endocytosis of PTEN. Flurbiprofen may exert an anti-tumor effect on thyroid cancer by blocking the interaction between HIP1R and PTEN.

Update on the systemic management of radioactive iodine refractory differentiated thyroid cancer (Review)

The incidence of differentiated thyroid cancer (DTC) has increased over the last few decades, though it remains to be a rare disease. The prognosis of DTC is excellent; its treatment includes surgery (near-/total thyroidectomy), which is usually followed by remnant thyroid bed ablation using radio-iodine, as well as a risk-stratified follow-ups, including hormone replacement. Treatment of patients who are non-responsive to radioactive iodine (RAI) remains a challenge. Targeted therapies for RAI refractory DTC act primarily through inhibition of cell proliferation, survival and angiogenesis. Tyrosine kinase inhibitors (TKI) have achieved prolonged responses and improved progression-free survival, thereby representing a shift in the treatment of advanced thyroid cancer. There will be number of targeted treatment options for this patient population in the near future. Evidence regarding which drug should be used first and whether there is crossover drug resistance between these drugs is still lacking. Clinicians should be able to choose precisely which patients should be treated with novel targeted therapies after taking into account the following facts: i) TKIs have still not demonstrated a survival benefit. ii) The adverse effects of long-lasting treatment with TKIs could worsen quality of life, which is mostly excellent in these patients before starting treatment with these agents.

Pharmacological effects of vinorelbine in combination with lenvatinib in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is a rare neoplasia with a poor prognosis. Proliferation and apoptosis assays were performed on ATC cell lines (8305C, 8505C) exposed to vinorelbine, lenvatinib, as well as to concomitant combinations. ABCB1, ABCG2 and CSF-1 mRNA expression was evaluated by real time PCR. The relative levels of pospho Akt were investigated as part of a human phospho-kinase array analysis, and CSF-1 and VEGFR-2 protein levels were measured by ELISA. The intracellular concentration of lenvatinib in ATC cells was measured by combined reversed-phase liquid chromatography-tandem mass spectrometry. An ATC subcutaneous xenograft tumor model in nude mice was treated with vinorelbine, lenvatinib, or vinorelbine plus lenvatinib. After treatment with vinorelbine, lenvatinib, a significant antiproliferative effect in ATC cell lines was observed. The concomitant treatment of vinorelbine and lenvatinib revealed synergism for all the fractions of affected cells. A decrease in ABCB1 expression was reported in both ATC cell lines treated with the lenvatinib plus vinorelbine combination, as was an increase in the intracellular concentration of lenvatinib. The combination caused a decrease in Akt, GSK3α/β, PRAS40 and Src phosphorylation, and in both CSF-1 mRNA and protein levels. In the subcutaneous tumor model, the combination reduced the tumor volume during the treatment period. Our results establish the synergistic ATC antitumor activity of a vinorelbine and lenvatinib combination.

Synergistic activity of linifanib and irinotecan increases the survival of mice bearing orthotopically implanted human anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is the most aggressive form of thyroid cancer, and novel combined therapies are urgently needed to prolong patient survival. No data are currently available on the preclinical activity of the combination of linifanib, a CSF-1R inhibitor, and irinotecan in ATC. The aim of the study was to evaluate the in vitro and in vivo activity of linifanib plus irinotecan. Proliferation and apoptosis assays were performed on 8305C and 8505C human ATC cell lines exposed to SN-38, the active metabolite of irinotecan, linifanib alone, and their concomitant combination. Synergism was evaluated by the combination index method. Quantification of pospho-CSF-1R levels was performed by ELISA. In vivo ATC orthotopic xenografts were treated with the single drugs, or their combination, to evaluate their impact on survival. Histology and immunohistochemistry were performed on ATC tissue samples. Both SN-38 and linifanib inhibited in vitro the proliferation of 8305C and 8505C cells in a concentration-dependent manner, whereas their concomitant treatment revealed a strong synergism in the ATC cells. A significant pro-apoptotic activity was found in both ATC cell lines treated with linifanib alone and in combination with SN-38. Moreover, linifanib significantly decreased the levels of phospho-CSF-1R after 24 h and 72 h in both 8505C and 8305C cells, and this was also observed with the concomitant administration of SN-38. In vivo, the combination of linifanib and irinotecan produced a greater survival result than either monotherapy, and resulted in a significant higher median survival. In some of the mice the combination produced a complete response with a macroscopic disappearance of the disease, as confirmed by histology. In conclusion, the synergistic ATC antitumor activity of linifanib/irinotecan combination significantly increased the survival of ATC affected mice and induced some complete responses, suggesting a potential role of this schedule in ATC patient's treatment.

Dose-dependent regulation of mitochondrial function and cell death pathway by sorafenib in liver cancer cells

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the fourth most frequent cause of cancer-related death worldwide. Sorafenib is the first line recommended therapy for patients with locally advanced/metastatic HCC. The low response rate is attributed to intrinsic resistance of HCC cells to Sorafenib. The potential resistance to Sorafenib-induced cell death is multifactorial and involves all hallmarks of cancer. However, the presence of sub-therapeutic dose can negatively influence the antitumoral properties of the drug. In this sense, the present study showed that the sub-optimal Sorafenib concentration (10 nM) was associated with activation of caspase-9, AMP-activated protein kinase (AMPK), sustained autophagy, peroxisome proliferator-activated receptor-coactivator 1α (PGC-1α) and mitochondrial function in HepG2 cells. The increased mitochondrial respiration by Sorafenib (10 nM) was also observed in permeabilized HepG2 cells, but not in isolated rat mitochondria, which suggests the involvement of an upstream component in this regulatory mechanism. The basal glycolysis was dose dependently increased at early time point studied (6 h). Interestingly, Sorafenib increased nitric oxide (NO) generation that played an inhibitory role in mitochondrial respiration in sub-therapeutic dose of Sorafenib. The administration of sustained therapeutic dose of Sorafenib (10 µM, 24 h) induced mitochondrial dysfunction and dropped basal glycolysis derived acidification, as well as increased oxidative stress and apoptosis in HepG2. In conclusion, the accurate control of the administered dose of Sorafenib is relevant for the potential prosurvival or proapoptotic properties induced by the drug in liver cancer cells.

The substance P and neurokinin-1 receptor system in human thyroid cancer: an immunohistochemical study

To develop a new therapeutic strategy against thyroid cancer (TC), the expression of both substance P (SP) and neurokinin-1 receptor (NK-1R) must be demonstrated in TC cells. This study aims to examine by immunohistochemistry, the localization of SP and the NK-1R in human TC samples (papillary, follicular, medullary, anaplastic), in metastasis and in healthy thyroid samples. SP and the NK-1R were expressed in all normal and TC samples. In healthy glands, SP was located in follicular cells (nucleus) and colloid and NK-1R in follicular cells (cytoplasm) and stroma. In TC samples, SP was visualized in follicular cells (nucleus and cytoplasm), stroma and colloid and NK-1R in follicular cells (cytoplasm), stroma and colloid. A semiquantitative scoring system (Allred Unit Scoring System) was applied. The expression (Allred total score) of SP and NK-1R was weaker in normal thyroid glands than in TC. In comparison with TC samples, a lower intensity/proportion of SP (nucleus and cytoplasm of follicular cells; stroma) was observed in normal samples. By contrast, in the colloid of TC samples the presence of SP was lower than in normal samples. In comparison with TC samples, the presence of the NK-1R in the cytoplasm of follicular cells and colloid was lower in normal thyroid samples, whereas the expression of this receptor in the stroma was higher. The results reported in this study suggest that the NK-1R could be a new target for the treatment of TC and use of the NK-1R antagonists could serve as a new anti-TC therapeutic strategy.

Lenvatinib and sorafenib for differentiated thyroid cancer after radioactive iodine: a systematic review and economic evaluation

BACKGROUND

Thyroid cancer is a rare cancer, accounting for only 1% of all malignancies in England and Wales. Differentiated thyroid cancer (DTC) accounts for ≈94% of all thyroid cancers. Patients with DTC often require treatment with radioactive iodine. Treatment for DTC that is refractory to radioactive iodine [radioactive iodine-refractory DTC (RR-DTC)] is often limited to best supportive care (BSC).

OBJECTIVES

We aimed to assess the clinical effectiveness and cost-effectiveness of lenvatinib (Lenvima®; Eisai Ltd, Hertfordshire, UK) and sorafenib (Nexar®; Bayer HealthCare, Leverkusen, Germany) for the treatment of patients with RR-DTC.

DATA SOURCES

EMBASE, MEDLINE, PubMed, The Cochrane Library and EconLit were searched (date range 1999 to 10 January 2017; searched on 10 January 2017). The bibliographies of retrieved citations were also examined.

REVIEW METHODS

We searched for randomised controlled trials (RCTs), systematic reviews, prospective observational studies and economic evaluations of lenvatinib or sorafenib. In the absence of relevant economic evaluations, we constructed a de novo economic model to compare the cost-effectiveness of lenvatinib and sorafenib with that of BSC.

RESULTS

Two RCTs were identified: SELECT (Study of [E7080] LEnvatinib in 131I-refractory differentiated Cancer of the Thyroid) and DECISION (StuDy of sorafEnib in loCally advanced or metastatIc patientS with radioactive Iodine-refractory thyrOid caNcer). Lenvatinib and sorafenib were both reported to improve median progression-free survival (PFS) compared with placebo: 18.3 months (lenvatinib) vs. 3.6 months (placebo) and 10.8 months (sorafenib) vs. 5.8 months (placebo). Patient crossover was high (≥ 75%) in both trials, confounding estimates of overall survival (OS). Using OS data adjusted for crossover, trial authors reported a statistically significant improvement in OS for patients treated with lenvatinib compared with those given placebo (SELECT) but not for patients treated with sorafenib compared with those given placebo (DECISION). Both lenvatinib and sorafenib increased the incidence of adverse events (AEs), and dose reductions were required (for > 60% of patients). The results from nine prospective observational studies and 13 systematic reviews of lenvatinib or sorafenib were broadly comparable to those from the RCTs. Health-related quality-of-life (HRQoL) data were collected only in DECISION. We considered the feasibility of comparing lenvatinib with sorafenib via an indirect comparison but concluded that this would not be appropriate because of differences in trial and participant characteristics, risk profiles of the participants in the placebo arms and because the proportional hazard assumption was violated for five of the six survival outcomes available from the trials. In the base-case economic analysis, using list prices only, the cost-effectiveness comparison of lenvatinib versus BSC yields an incremental cost-effectiveness ratio (ICER) per quality-adjusted life-year (QALY) gained of £65,872, and the comparison of sorafenib versus BSC yields an ICER of £85,644 per QALY gained. The deterministic sensitivity analyses show that none of the variations lowered the base-case ICERs to < £50,000 per QALY gained.

LIMITATIONS

We consider that it is not possible to compare the clinical effectiveness or cost-effectiveness of lenvatinib and sorafenib.

CONCLUSIONS

Compared with placebo/BSC, treatment with lenvatinib or sorafenib results in an improvement in PFS, objective tumour response rate and possibly OS, but dose modifications were required to treat AEs. Both treatments exhibit estimated ICERs of > £50,000 per QALY gained. Further research should include examination of the effects of lenvatinib, sorafenib and BSC (including HRQoL) for both symptomatic and asymptomatic patients, and the positioning of treatments in the treatment pathway.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017055516.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Effects of Pazopanib Monotherapy vs. Pazopanib and Topotecan Combination on Anaplastic Thyroid Cancer Cells

The purpose of this study was to examine pazopanib/topotecan combination activity vs. pazopanib monotherapy on anaplastic thyroid cancer (ATC) cells. Proliferation analyses were performed on ATC cell lines administered for 72 h with pazopanib and topotecan alone and to their simultaneous combination. Pazopanib and topotecan produced a strong synergism on ATC cells, calculated by the combination index, increasing the intracellular concentrations of topotecan lactone measured by high-performance liquid chromatography. Furthermore, a significantly decrease of the gene expression of ATP-binding cassette transporter G2 (ABCG-2), vascular endothelial growth factor (VEGF), hypoxia-inducible factor-1α (HIF-1α), and colony stimulating factor-1 (CSF-1) was presented in combination-treated ATC cells by real time PCR tests. In summary, the simultaneous association of pazopanib and topotecan established a highly synergistic ATC antiproliferative effect, suggesting a new possibility to translate this schedule into clinical trials.

[Clinical and morphological characteristics of thyroid tumors in children of the Chelyabinsk Region]

OBJECTIVE

To carry out a clinical and morphological analysis of thyroid cancer cases in the children of the Chelyabinsk Region.

SUBJECT AND METHODS

Thyroid tumor pathology was verified in 50 of the 196 patients aged 7-17 years, who had been operated on in 2000-2016. Clinical and morphological features, including immunohistochemical and ultrastructural characteristics of thyroid cancer, were studied.

RESULTS

Over the past 17 years, there has been a decline in the number of children with surgical thyroid diseases, including thyroid carcinomas. There is a predominance of papillary carcinoma (70%) that is characterized by more aggressive clinical and morphological signs than follicular and medullary thyroid carcinoma. The immunophenotype of follicular cell tumors in children is characterized by the expression of growth factors (TTF-1, EGFR-384) and malignancy markers (mesothelial cell, AMACR (P504S), S 100).

CONCLUSION

The vector change (decrease) in the long-term unfavorable trend toward an increasing incidence of thyroid cancer in children of the Chelyabinsk Region is currently accompanied by the pathomorphism of thyroid carcinoma.

[Imaging of medullary thyroid carcinoma]

BACKGROUND

About 10% of thyroid cancers are medullary thyroid carcinoma (MTC) and can occur sporadically, familially and in the context of type II multiple endocrine neoplasia (MEN). Imaging plays a pivotal role in screening family members and in diagnosis.

DIAGNOSTIC METHODS

Diagnosis is based on ultrasound (US), thyroid scintigraphy, serum calcitonin and carcinoembryonic antigen (CEA) as well as fine needle biopsy. High-resolution US is the most important imaging method for locoregional staging, combined with computed tomography (CT) of the mediastinum. Positron emission tomography (PET-CT) using 18-F-DOPA is particularly suited for suspected occult metastases in case of rising tumor markers in serum.

FINDINGS AND COURSE OF DISEASE

Diagnosis is made based on cytologic findings in a hypoechoic, cold thyroid nodule, combined with an elevation of serum calcitonin and CEA. US is the most important imaging modality during routine follow-up. CT is indicated for suspected mediastinal, lung, or liver metastases. CT should be replaced by MRI as early as possible to prevent significant cumulative radiation doses over time.

RECENT CLINICAL DEVELOPMENTS

Although MTC is curable by surgery only, owing to its radio- and chemoresistance, the disease will often progress only slowly, and even patients with metastases will frequently survive 10 years or longer. For more aggressive variants and late symptomatic stages, targeted drugs that have the potential to indicate stabilization or even a partial remission of the disease are under clinical investigation or already approved.

Transcriptional targeting of oncogene addiction in medullary thyroid cancer

Metastatic medullary thyroid cancer (MTC) is incurable and FDA-approved kinase inhibitors that include oncogenic RET as a target do not result in complete responses. Association studies of human MTCs and murine models suggest that the CDK/RB pathway may be an alternative target. The objective of this study was to determine if CDKs represent therapeutic targets for MTC and to define mechanisms of activity. Using human MTC cells that are either sensitive or resistant to vandetanib, we demonstrate that palbociclib (CDK4/6 inhibitor) is not cytotoxic to MTC cells but that they are highly sensitive to dinaciclib (CDK1/2/5/9 inhibitor) accompanied by reduced CDK9 and RET protein and mRNA levels. CDK9 protein was highly expressed in 83 of 83 human MTCs and array-comparative genomic hybridization had copy number gain in 11 of 30 tumors. RNA sequencing demonstrated that RNA polymerase II-dependent transcription was markedly reduced by dinaciclib. The CDK7 inhibitor THZ1 also demonstrated high potency and reduced RET and CDK9 levels. ChIP-sequencing using H3K27Ac antibody identified a superenhancer in intron 1 of RET. Finally, combined inhibition of dinaciclib with a RET kinase inhibitor was synergistic. In summary, we have identified what we believe is a novel mechanism of RET transcription regulation that potentially can be exploited to improve RET therapeutic targeting.

Reduced Retinoblastoma Protein Expression Is Associated with Decreased Patient Survival in Medullary Thyroid Cancer

BACKGROUND

The retinoblastoma (RB) transcriptional corepressor 1 protein functions to slow cell-cycle progression. Inactivation of RB by reduced expression and/or hyperphosphorylation allow for enhanced progression through the cell cycle. Murine models develop medullary thyroid carcinoma (MTC) after generalized loss of RB. However, RB expression in MTC has only been evaluated in a small number of tumors, with differing results. The objective of this study was to determine whether reduced expression of RB and/or overexpression of hyperphosphorylated RB predict MTC aggressive behavior.

METHODS

Formalin-fixed, paraffin-embedded primary thyroid tumors and lymph node metastases from MTC patients were evaluated for calcitonin, RB, and phosphorylated RB (pRB) expression by immunohistochemistry. Two expert pathologists evaluated the slides in a blinded manner, and the immunohistochemistry results were compared to disease-specific survival as a primary endpoint.

RESULTS

Seventy-four MTC samples from 56 patients were analyzed in this study, including 51 primary tumors and 23 lymph node metastases. The median follow-up time was 6.75 years after surgery (range 0.64-24.30 years), and the median primary tumor size was 30 mm (range 6-96 mm). Sixty-six percent of cases were classified as stage IV. RB nuclear expression was diffusely present in 88% of primary tumors and 78% of lymph node metastases. Nuclear pRB expression was present in 22% of primary tumors and 22% of lymph node metastases. On univariate analysis, reduced RB (<75% tumor cell staining) trended with lower MTC-specific survival for primary tumor and metastatic nodes (primary tumor hazard ratio = 3.54 [confidence interval 0.81-15.47], p = 0.08; and lymph node hazard ratio = 4.35 [confidence interval 0.87-21.83], p = 0.05). For primary tumors, multivariable analysis showed that low nuclear RB expression was independently associated with worse disease-specific (p = 0.01) and overall (p = 0.02) survival. pRB levels were not associated with survival for either primary tumor or lymph node metastases.

CONCLUSIONS

Reduced RB expression is associated with decreased patient survival in univariate and multivariable analyses, independent from patient age at surgery or advanced TNM stage. Future studies involving larger MTC patient populations are warranted to determine if lower RB expression levels may serve as a biomarker for aggressive disease in patients with MTC.

Recurrent Metastatic Medullary Thyroid Carcinoma: A Case of Sustained Response to Prolonged Treatment with Somatostatin Analogues

BACKGROUND

Medullary thyroid carcinoma (MTC) is a rare disease. Treatment options for recurrent disease are limited. Although somatostatin analogues might have a role as anticancer agents in MTC, the evidence is inconclusive.

PATIENT FINDINGS

A 64-year-old male was diagnosed with MTC in January 2010. Total thyroidectomy with neck dissection (stage IVA, pT2pN1bM0, R1) was performed, followed by adjuvant locoregional radiotherapy. Two years later, in January 2012, the patient developed recurrent metastatic disease, evidenced by elevated carcinoembryonic antigen (CEA) and calcitonin levels, and a positive uptake (Octreoscan^®) in the right adrenal gland and pancreatic head. A further computed tomography (CT) scan revealed metastases in the right adrenal gland, the duodenal bulb, and two pancreatic lesions, which were later confirmed as metastases by endoscopic ultrasound and cytology, and therefore salvage surgery was ruled out. Treatment with Somatuline Autogel^® (120 mg subcutaneously every 28 days) was initiated in September 2012, and 11 months later, calcitonin and CEA levels had both normalized, and a new CT scan showed that the metastatic lesions had disappeared or shrunk markedly. An Octreoscan performed in January 2014 and a repeat contrast-enhanced CT in February 2014 showed sustained tumor response. The patient remained in remission until February 2016, when a new Octreoscan revealed recurrent disease in the right adrenal gland, a nodule in the right upper pulmonary lobe, and nodal disease in the celiac trunk. CEA and calcitonin levels remained normal, although with a slight increase in calcitonin levels (47 pg/mL).

SUMMARY

The unusual case is described of a patient with metastatic MTC involving the adrenal gland, duodenum, and pancreas, who achieved a sustained response to somatostatin analogues after 11 months of treatment. The patient remained in remission for nearly 3.5 years from initiation of treatment with somatostatin analogues.

CONCLUSIONS

The case presented here is one of the few described in the literature in which long-term treatment with somatostatin analogues resulted in a sustained tumor response in a patient with metastatic recurrent MTC following curative-intent surgery. These findings suggest that prolonged treatment with somatostatin analogues may be beneficial in asymptomatic cases with a low tumor burden and a positive Octreoscan following recurrence. More data are needed to confirm these findings.

Synergistic efficacy of irinotecan and sunitinib combination in preclinical models of anaplastic thyroid cancer

The identification of new therapeutic strategies is urgently needed for the management of patients affected by anaplastic thyroid cancer (ATC) due to their short survival and poor prognosis. Aim of the study was to determine the activity of the combination irinotecan/sunitinib on ATC cell growth in vitro and the antitumor effects in vivo. Proliferation assays were performed for 72 h on ATC cell lines exposed to the combination of SN-38, the active metabolite of irinotecan, and sunitinib. The simultaneous combination of sunitinib and SN-38, quantified by the combination index, determined a high synergism on ATC cells, increasing the intracellular concentrations of SN-38. Moreover, the synergistic combination greatly decreases the gene expression and the protein levels of vascular endothelial growth factor, colony stimulating factor 1 and ATP-binding cassette transporter G2 in ATC cells. A significant in vivo antitumor effect was observed in ATC xenografts with the simultaneous combination of irinotecan and sunitinib if compared to monotherapy. The simultaneous combination of irinotecan and sunitinib, in vitro and in vivo demonstrated a significant, synergistic ATC antitumor activity, suggesting a possible and rapid translation of this schedule into the clinics.

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.

Hepatocyte Growth Factor/C-Met Axis in Thyroid Cancer: From Diagnostic Biomarker to Therapeutic Target

The hepatocyte growth factor (HGF)/c-met axis plays a crucial role in cancer development by promoting cellular proliferation, motility, and morphogenesis, as well as angiogenesis. Different cellular distributions of both the ligand and the receptor in benign vs malignant lesions indicate this biological system as a candidate for a diagnostic biomarker of malignancy occurring in endocrine glands, such as the thyroid and pituitary. Furthermore, the HGF/c-met expression may help to identify a subset of patients eligible for potential targeted therapies with HGF/c-met inhibitors or antagonists in thyroid tumour, as well as in other malignancies. This may be relevant for iodine-refractory cancers, the treatment of which is still a major challenge. With this in mind, HGF/c-met expression in thyroid cancer tissue may be useful for prognostic and therapeutic stratification of patients.

Utility of proGRP as a tumor marker in the medullary thyroid carcinoma

Background:

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor caused by a malignant transformation in the parafollicular C-cells of the thyroid, where calcitonin (CT) is released. Nowadays the main tumor markers (TM) used in the diagnosis and follow-up of MTC patients are CT and carcinoembryonic antigen (CEA). Nonetheless, progastrin releasing peptide (proGRP) has been recently proposed as a TM useful in the MTC. Our aims were to investigate the release of proGRP in thyroid tumors, its role in the assessment of advanced MTC and its utility in the differential diagnosis between MTC and non-MTC thyroid tumors.

Methods:

Serum samples from 22 patients with MTC and 16 with non-MTC were collected. Patients were classified into advanced cancer or no evidence of disease (NED). ProGRP was performed by Architect (Abbot Diagnostics), CT by Liaison (Diasorin) and CEA by Cobas E601(Roche Diagnostics).

Results:

ProGRP median concentration in advanced MTC was significantly higher (1398.4 pg/mL) when compared with non-MTC, either in advanced disease (24.9 pg/mL) or NED (14.6 pg/mL). In non-MTC patients, proGRP median concentration was below its cutoff level (50 pg/mL). Similar to CT, proGRP was able to detect 88.9% of MTC patients, but with a slightly lower specificity of 76.9%. Using proGRP together with CT the sensitivity increased to 100%.

Conclusions:

The low prevalence of this malignancy strongly recommends further collaborative studies, mainly focused on monitoring proGRP during tyrosine kinase inhibitors treatment for early detection of resistance and assessing its usefulness to avoid the observed false positive fluctuations that occur with CT and CEA.

Lenvatinib: A Review in Refractory Thyroid Cancer

Lenvatinib (Lenvima®) is an oral, multi-targeted tyrosine kinase inhibitor (TKI) of vascular endothelial growth factor (VEGF) receptors 1, 2 and 3, fibroblast growth factor receptors 1, 2, 3 and 4, platelet-derived growth factor receptor alpha, and RET and KIT signalling networks, which are implicated in tumour growth and maintenance. In the EU and USA, lenvatinib is indicated for the treatment of locally recurrent or metastatic progressive, radioiodine-refractory differentiated thyroid cancer (RR-DTC). This approval was based on the results of the randomized, double-blind, multinational, phase 3 SELECT study, in which lenvatinib significantly improved median progression-free survival (PFS) and overall response rate compared with placebo in patients with RR-DTC. The PFS benefit with lenvatinib was seen in all pre-specified subgroups, including patients who had received either one or no prior VEGF-targeted therapy. Moreover, the PFS benefit with lenvatinib was maintained regardless of BRAF or RAS mutation status. The safety and tolerability profile of lenvatinib in SELECT was consistent with that of other VEGF/VEGF receptor-targeted therapies and was mostly manageable. Hypertension was the most common treatment-related adverse event in lenvatinib-treated patients, but only infrequently led to discontinuation of the drug. Although not collected in SELECT, information on quality of life would be useful in assessing the overall impact of therapy on the patient. This notwithstanding, the data which are available indicate that lenvatinib is an effective and generally well-tolerated treatment option for patients with RR-DTC. Lenvatinib, therefore, offers an acceptable alternative to sorafenib--currently, the only other TKI approved for this indication.

HER2 Analysis in Sporadic Thyroid Cancer of Follicular Cell Origin

The Epidermal Growth Factor Receoptor (EGFR) family member human epidermal growth factor receptor 2 (HER2) is overexpressed in many human epithelial malignancies, representing a molecular target for specific anti-neoplastic drugs. Few data are available on HER2 status in differentiated thyroid cancer (DTC). The present study was aimed to investigate HER2 status in sporadic cancers of follicular cell origin to better clarify the role of this receptor in the stratification of thyroid cancer. By immunohistochemistry and fluorescence in-situ hybridization, HER2 expression was investigated in formalin-fixed paraffin-embedded surgical specimens from 90 DTC patients, 45 follicular (FTC) and 45 papillary (PTC) histotypes. No HER2 immunostaining was recorded in background thyroid tissue. By contrast, overall HER2 overexpression was found in 20/45 (44%) FTC and 8/45 (18%) PTC, with a significant difference between the two histotypes (p = 0.046). Five of the six patients who developed metastatic disease during a median nine-year follow-up had a HER2-positive tumor. Therefore, we suggest that HER2 expression may represent an additional aid to identify a subset of patients who are characterized by a worse prognosis and are potentially eligible for targeted therapy.

Signaling pathways in medullary thyroid carcinoma: therapeutic implications

Medullary thyroid cancer (MTC) is the third most frequent thyroid cancer arising from thyroid parafollicular cells. Surgery is the first-line strategy in treatment of MTC but disease relapse and patient's death have been observed in approximately two out of three of MTC cases. Identification of molecular mechanisms and different signaling pathways has offered new insights for disease treatment. The development of tyrosine kinase inhibitors targeting these pathways has provided a promising landscape for prevention of progression in patients with advanced metastatic MTC. In this review article different altered molecular pathways implicated in the development of MTC and the therapeutic strategies based on targeting the identified signaling pathways have been summarized.

TRAP1 regulates cell cycle and apoptosis in thyroid carcinoma cells

Tumor necrosis factor receptor-associated protein 1 (TRAP1) is a heat shock protein 90 (HSP90) molecular chaperone upregulated in several human malignancies and involved in protection from apoptosis and drug resistance, cell cycle progression, cell metabolism and quality control of specific client proteins. TRAP1 role in thyroid carcinoma (TC), still unaddressed at present, was investigated by analyzing its expression in a cohort of 86 human TCs and evaluating its involvement in cancer cell survival and proliferation in vitro Indeed, TRAP1 levels progressively increased from normal peritumoral thyroid gland, to papillary TCs (PTCs), follicular variants of PTCs (FV-PTCs) and poorly differentiated TCs (PDTCs). By contrast, anaplastic thyroid tumors exhibited a dual pattern, the majority being characterized by high TRAP1 levels, while a small subgroup completely negative. Consistently with a potential involvement of TRAP1 in thyroid carcinogenesis, TRAP1 silencing resulted in increased sensitivity to paclitaxel-induced apoptosis, inhibition of cell cycle progression and attenuation of ERK signaling. Noteworthy, the inhibition of TRAP1 ATPase activity by pharmacological agents resulted in attenuation of cell proliferation, inhibition of ERK signaling and reversion of drug resistance. These data suggest that TRAP1 inhibition may be regarded as potential strategy to target specific features of human TCs, i.e., cell proliferation and resistance to apoptosis.

Candidate microRNAs as biomarkers of thyroid carcinoma: a systematic review, meta-analysis, and experimental validation

Thyroid cancer is one of the most common carcinomas of the endocrine system with an increasing incidence. A growing number of studies have focused on the diagnostic and prognostic values of dysregulated microRNAs (miRNAs) in thyroid carcinoma. However, differences in the measurement platforms, variations in lab protocols, and small sample sizes can make gene profiling data incomparable. A meta-review of the published studies that compared miRNA expression data of thyroid carcinoma and paired normal tissues was performed to identify potential miRNA biomarkers of thyroid carcinoma with the vote-counting strategy. Two hundred and thirty-six aberrantly expressed miRNAs were reported in 19 microRNA expression profiling studies. Among them, 138 miRNAs were reported in at least two studies. We also provided a meta-signature of differentially expressed miRNAs between individual histological types of thyroid carcinoma and normal tissues. The experimental validation with qRT-PCR analysis verified that the profiles identified with the meta-review approach could effectively discriminate papillary thyroid carcinoma tissues from paired noncancer tissues. The meta-review of miRNA expression profiling studies of thyroid carcinoma would provide information on candidate miRNAs that could potentially be used as biomarkers in thyroid carcinoma.

Safety and efficacy profile of lenvatinib in cancer therapy: a systematic review and meta-analysis

To systematically review the safety and efficacy of lenvatinib in the treatment of patients, we retrieved all the relevant clinical trials on the adverse events (AEs) and survival outcomes of lenvatinib through PubMed, Medline, Embase, Web of Science and Cochrane Collaboration's Central register of controlled trial. Fourteen eligible studies involving a total of 978 patients were included in our analysis. The most common all-grade AEs observed in patients treated with lenvatinib were hematuria (56.6%), fatigue (52.2%) and decreased appetite (50.5%). The most frequently observed grade ≥3 AEs were thrombocytopenia (25.4%), hypertension (17.7%) and edema peripheral (15.5%). The incidences of both all-grade and high-grade hypertension were significantly increased. Meanwhile, the controlled trial suggested that progression free survival (PFS) was significantly longer in the lenvatinib group than the placebo group. Subgroup analyses showed that mean PFS for renal cell carcinoma was 10.933±1.828 months (95% CI 7.350-14.515, p < 0.001), and that for thyroid cancer was 18.344±0.083 months (95% CI 18.181-18.506, p < 0.001). In conclusion, lenvatinib is an effective agent in thyroid cancer. Early monitoring and effective management of side effects are crucial for the safe use of this drug.

Modulation of Autophagy by Sorafenib: Effects on Treatment Response

The multikinase inhibitor sorafenib is, at present, the only drug approved for the treatment of hepatocellular carcinoma (HCC), one of the most lethal types of cancer worldwide. However, the increase in the number of sorafenib tumor resistant cells reduces efficiency. A better knowledge of the intracellular mechanism of the drug leading to reduced cell survival could help to improve the benefits of sorafenib therapy. Autophagy is a bulk cellular degradation process activated in a broad range of stress situations, which allows cells to degrade misfolded proteins or dysfunctional organelles. This cellular route can induce survival or death, depending on cell status and media signals. Sorafenib, alone or in combination with other drugs is able to induce autophagy, but cell response to the drug depends on the complex integrative crosstalk of different intracellular signals. In cancerous cells, autophagy can be regulated by different cellular pathways (Akt-related mammalian target of rapamycin (mTOR) inhibition, 5′ AMP-activated protein kinase (AMPK) induction, dissociation of B-cell lymphoma 2 (Bcl-2) family proteins from Beclin-1), or effects of some miRNAs. Inhibition of mTOR signaling by sorafenib and diminished interaction between Beclin-1 and myeloid cell leukemia 1 (Mcl-1) have been related to induction of autophagy in HCC. Furthermore, changes in some miRNAs, such as miR-30α, are able to modulate autophagy and modify sensitivity in sorafenib-resistant cells. However, although AMPK phosphorylation by sorafenib seems to play a role in the antiproliferative action of the drug, it does not relate with modulation of autophagy. In this review, we present an updated overview of the effects of sorafenib on autophagy and its related activation pathways, analyzing in detail the involvement of autophagy on sorafenib sensitivity and resistance.

Emerging strategies for managing differentiated thyroid cancers refractory to radioiodine

Efficient treatment of radio refractory thyroid cancer is still a major challenge. The recent identification of genetic and epigenetic alterations present in almost all differentiated tumors has revealed novel molecular targets, which can hopefully be exploited to create new treatments for these tumors. This review looks briefly at some of the innovative strategies currently being investigated for the treatment the radioiodine-resistant thyroid cancers.

Sequential treatment in disseminated well- and intermediate-differentiated pancreatic neuroendocrine tumors: Common sense or low rationale?

Fortunately, the landscape of the systemic treatment for grade 1 and 2 pancreatic neuroendocrine tumors has changed in the last decade with at least four different alternatives approved in the field. Chemotherapy, somatostatin analogues, sunitinib and everolimus remind valid options according to the most referenced international guidelines. However, and although this is something done in the routine practice, there is a lack of evidence for the use of any of these strategies after failure to the others. Moreover, further sequential alternatives in third or fourth line have never been tested prospectively. The need for a better understanding of the rationale to sequence different systemic options is even greater in non-pancreatic neuroendocrine tumors since available therapies are scarce. Sequential strategies in other solid tumors have led to a clear improvement in overall survival. This is also believed to occur in neuroendocrine tumors but no clear data on it has been delivered yet. We postulate that the different mode of action of the systemic options available for the treatment of neuroendocrine tumors may avoid the complete resistance of one option after the other and that sequential use of these agents will be translated into a longer overall survival of patients. Prospective and randomized trials that seek for the activity of drugs after failure to another systemic alternatives are highly needed in this field of neuroendocrine tumors.

Metabolomics of papillary thyroid carcinoma tissues: potential biomarkers for diagnosis and promising targets for therapy

Papillary thyroid carcinoma (PTC) is the most common pathological type of thyroid cancer. Our study was to construct a tissue-targeted metabolomics analysis method based on untargeted and targeted metabolic multi-platforms to identify a comprehensive PTC metabolic network in clinical samples. We applied untargeted gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) for preliminary screening of potential biomarkers. With diagnostic models constructed using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA), 45 differentially abundant metabolites with a variable importance in the projection (VIP) value greater than 1 and a P value less than 0.05 were identified, and we show that our approach was able to discriminate PTC tissues from healthy tissues. We then performed validation experiments based on targeted GC-TOF-MS combined with ultra-high-performance liquid chromatography-triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) through constructing linear standard curves of analytes. Ultimately, galactinol, melibiose, and melatonin were validated as significantly altered metabolites (p < 0.05). These three metabolites were defined as a combinatorial biomarker to assist needle biopsy for PTC diagnosis as demonstrated by receiver operating characteristic (ROC) curve analysis, which revealed an area under the ROC curve (AUC) value of 0.96. Based on the metabolite enrichment analysis results, the galactose metabolism pathway was regarded as an important factor influencing PTC development by affecting energy metabolism. Alpha-galactosidase (GLA) was considered to be a potential target for PTC therapy.

Increased Expression of FGF19 Contributes to Tumor Progression and Cell Motility of Human Thyroid Cancer

OBJECTIVE

Numerous reports indicate a role for aberrant expression of fibroblast growth factor 19 (FGF19) in tumor development and progression, and several drugs have been developed to target it. The aim of this study was to investigate the clinical significance of FGF19 and examine whether it plays any roles in progression of thyroid cancer.

STUDY DESIGN

Translation research.

SETTING

Navy General Hospital of Chinese PLA, China.

SUBJECTS AND METHODS

Expression patterns of FGF19 protein in 100 paired formalin-fixed and paraffin-embedded cancerous and adjacent noncancerous tissues from patients with thyroid cancer were detected by immunohistochemistry. Then, in vitro migration and invasion assays of siRNA-targeted FGF19-transfected cells were performed.

RESULTS

Positive immunostaining of FGF19 protein expression was localized in cytoplasm with or without membrane of malignant cells and was observed in 82 (82.0%) of 100 patients with thyroid cancer. Statistically, the expression level of FGF19 protein in thyroid cancer tissues was significantly higher than that in normal tissues. In addition, FGF19 overexpression was significantly associated with the advanced tumor node metastasis staging (P = .008), the presence of extrathyroidal invasion (P = .01), lymph nodes metastasis (P = .01), and distant metastasis (P = .02). Furthermore, knockdown of FGF19 by transfection of siRNA-FGF19 could efficiently suppress the migration and invasion abilities of thyroid cancer cells in vitro.

CONCLUSION

Our data revealed that the increased expression of FGF19 might be involved in the malignant behaviors of thyroid cancer, highlighting its potential as a molecular marker for early diagnosis and as a possible target for therapeutic intervention of this disease.

Lenvatinib: first global approval

Lenvatinib (Lenvima™) is a multitargeted receptor kinase inhibitor that inhibits the kinase activities of vascular endothelial-derived growth factor receptors 1, 2 and 3, fibroblast growth factor receptors 1, 2, 3 and 4, platelet-derived growth factor receptor α, RET and KIT. In addition to their role in normal cellular function, these kinases have been implicated in pathogenic angiogenesis, tumour growth and cancer progression. Lenvatinib is being developed by Eisai Co. Ltd for the treatment of solid tumours, primarily for differentiated thyroid cancer, and other malignancies. A capsule formulation of the drug has received approval in the USA for use in locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer. Lenvatinib is in pre-registration for this indication in the EU, Australia, Brazil, Canada, Japan, South Korea, Russia, Singapore and Switzerland, and is in phase 3 development in Argentina, Chile and Thailand. Lenvatinib has orphan designation in the EU and Japan for use in differentiated thyroid cancer. In addition, an ongoing global, phase 3 trial is evaluating the use of lenvatinib as first-line treatment in unresectable hepatocellular carcinoma. This article summarizes the milestones in the development of lenvatinib leading to this first approval in locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer.

Selective use of vandetanib in the treatment of thyroid cancer

Vandetanib is a once-daily orally available tyrosine kinase inhibitor that works by blocking RET (REarranged during Transfection), vascular endothelial growth factor receptor (VEGFR-2, VEGFR-3), and epidermal growth factor receptor and to a lesser extent VEGFR-1, which are important targets in thyroid cancer (TC). It is emerging as a potentially effective option in the treatment of advanced medullary thyroid cancer (MTC) and in dedifferentiated papillary thyroid cancer not responsive to radioiodine. The most important effect of vandetanib in aggressive MTC is a prolongation of progression-free survival and a stabilization of the disease. Significant side effects have been observed with the vandetanib therapy (as fatigue, hypertension, QTc prolongation, cutaneous rash, hand-and-foot syndrome, diarrhea, etc), and severe side effects can require the suspension of the drug. Several studies are currently under way to evaluate the long-term efficacy and tolerability of vandetanib in MTC and in dedifferentiated papillary TC. The efficacy of vandetanib in patients with MTC in long-term treatments could be overcome by the resistance to the drug. However, the effectiveness of the treatment could be ameliorated by the molecular characterization of the tumor and by the possibility to test the sensitivity of primary TC cells from each subject to different tyrosine kinase inhibitor. Association studies are evaluating the effect of the association of vandetanib with other antineoplastic agents (such as irinotecan, bortezomib, etc). Further research is needed to determine the ideal therapy to obtain the best response in terms of survival and quality of life.