Epidermal growth factor mutation as a diagnostic and therapeutic target in metastatic poorly differentiated thyroid carcinoma: a case report and review of the literature

High frequency of KRAS and EGFR mutation profiles in BRAF-negative thyroid carcinomas in Indonesia

OBJECTIVE

Thyroid cancer incidence has steadily increased in Indonesia. However, data on Kirsten rat sarcoma virus (KRAS) and EGFR mutations in thyroid cancer in Indonesia remain unavailable, except for BRAF-V600E, the most common BRAF gene mutation. This study aimed to analyze KRAS and EGFR mutation profiles in BRAF-V600E negative thyroid cancer samples.

RESULTS

BRAF-V600E mutations were found in papillary thyroid carcinomas in 40.3% patients with mean age of 53 years old. In BRAF-V600E-negative samples, 41.3% had KRAS mutations with mean age of 55.5 years old. KRAS mutation was found in 52.6% of follicular carcinomas and 47.4% of papillary thyroid carcinomas. Additionally, 45.7% had EGFR mutations in patients with mean age of 50.5 years old. EGFR mutation was found in 71.4% of papillary thyroid carcinoma and 28.6% of follicular carcinoma. Nearly half of the BRAF-V600E negative thyroid carcinoma samples harbored either KRAS or EGFR mutations. This finding suggests that in BRAF-V600E negative thyroid carcinoma samples, testing for RAS and EGFR mutation may be warranted for further therapeutic consideration.

High Expression of PDE8B and DUOX2 Associated with Ability of Metastasis in Thyroid Carcinoma

BACKGROUND

Hormone is an independent factor that induces differentiation of thyroid cancer (TC) cells. The thyroid-stimulating hormone (TSH) could promote the progression and invasion in TC cells. However, few genes related to hormone changes are studied in poorly differentiated metastatic TC. This study is aimed at constructing a gene set's coexpression correlation network and verifying the changes of some hub genes involved in regulating hormone levels.

METHODS

Microarray datasets of TC samples were obtained from public Gene Expression Omnibus (GEO) databases. R software and bioinformatics packages were utilized to identify the differentially expressed genes (DEGs), important gene module eigengenes, and hub genes. Subsequently, the Gene Ontology (GO) enrichment analysis was constructed to explore important biological processes that are associated with the mechanism of poorly differentiated TC. Finally, some hub gene expressions were validated through real-time PCR and immunoblotting.

RESULTS

Gene chip with category number GSE76039 was analyzed, and 1190 DEGs were screened with criteria of P < 0.05 and ∣log2foldchange | >2. Our analysis showed that human dual oxidase 2 (DUOX2) and phosphodiesterase 8B (PDE8B) are the two important hub genes in a coexpression network. In addition, the validated experimental results showed that the expression levels of both DUOX2 and PDE8B were elevated in poorly differentiated metastatic TC tissues.

CONCLUSION

This study identified and validated that DUOX2 and PDE8B were significantly associated with the metastasis ability of thyroid carcinoma.

Mutation and drug-specific intracellular accumulation of EGFR predict clinical responses to tyrosine kinase inhibitors

BACKGROUND

Clinical responses to EGFR tyrosine kinase inhibitors (TKIs) are restricted to tumors harboring specific activating mutations and even then, not all tyrosine kinase inhibitors provide clinical benefit. All TKIs however, effectively inhibit EGFR phosphorylation regardless of the mutation present.

METHODS

High-throughput, high-content imaging analysis, western blot, Reversed phase protein arrays, mass spectrometry and RT-qPCR.

FINDINGS

We show that the addition of TKIs results in a strong and rapid intracellular accumulation of EGFR. This accumulation mimicked clinical efficacy as it was observed only in the context of the combination of a TKI-sensitive mutation with a clinically effective (type I) TKI. Intracellular accumulation of EGFR was able to predict response to gefitinib in a panel of cell-lines with different EGFR mutations. Our assay also predicted clinical benefit to EGFR TKIs on a cohort of pulmonary adenocarcinoma patients (hazard ratio 0.21, P=0.0004 [Cox proportional hazard model]) and could predict the clinical response in patients harboring rare mutations with unknown TKI-sensitivity. All investigated TKIs, regardless of clinical efficacy, inhibited EGFR phosphorylation and downstream pathway activation, irrespective of the mutation present. Intracellular accumulation of EGFR depended on a continued presence of TKI indicating (type I) TKIs remain associated with the protein even after its dephosphorylation. Accumulation therefore is likely caused by two consecutive conformational changes, induced by both activating mutation and TKI, that combined block EGFR-membrane recycling.

INTERPRETATION

We report on an assay that mimics the discrepancy between molecular and clinical activity of EGFR-TKIs, which may allow response prediction in vitro and helps understand the mechanism of effective inhibitors.

Current Advances in Thyroid Cancer Management. Are We Ready for the Epidemic Rise of Diagnoses?

A rising incidence of thyroid cancers (TCs) mainly small tumors, observed during recent years, lead to many controversies regarding treatment strategies. TCs represent a distinct molecular background and clinical outcome. Although in most cases TCs are characterized by a good prognosis, there are some aggressive forms, which do not respond to standard treatment. There are still some questions, which have to be resolved to avoid dangerous simplifications in the clinical management. In this article, we focused on the current advantages in preoperative molecular diagnostic tests and histopathological examination including noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). We discussed the controversies regarding the extent of thyroid surgery and adjuvant radioiodine therapy, as well as new treatment modalities for radioiodine-refractory differentiated thyroid cancer (RR-DTC). Considering medullary thyroid cancer (MTC), we analyzed a clinical management based on histopathology and RET (ret proto-oncogene) mutation genotype, disease follow-up with a special attention to serum calcitonin doubling time as an important prognostic marker, and targeted therapy applied in advanced MTC. In addition, we provided some data regarding anaplastic thyroid cancer (ATC), a highly lethal neoplasm, which lead to death in nearly 100% of patients due to the lack of effective treatment options.

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.

New therapies for dedifferentiated papillary thyroid cancer

The number of thyroid cancers is increasing. Standard treatment usually includes primary surgery, thyroid-stimulating hormone suppressive therapy, and ablation of the thyroid remnant with radioactive iodine (RAI). Despite the generally good prognosis of thyroid carcinoma, about 5% of patients will develop metastatic disease, which fails to respond to RAI, exhibiting a more aggressive behavior. The lack of specific, effective and well-tolerated drugs, the scarcity of data about the association of multi-targeting drugs, and the limited role of radioiodine for dedifferentiated thyroid cancer, call for further efforts in the field of new drugs development. Rearranged during transfection (RET)/papillary thyroid carcinoma gene rearrangements, BRAF (B-RAF proto-oncogene, serine/threonine kinase) gene mutations, RAS (rat sarcoma) mutations, and vascular endothelial growth factor receptor 2 angiogenesis pathways are some of the known pathways playing a crucial role in the development of thyroid cancer. Targeted novel compounds have been demonstrated to induce clinical responses and stabilization of disease. Sorafenib has been approved for differentiated thyroid cancer refractory to RAI.

Molecular Targeted Therapies of Aggressive Thyroid Cancer

Differentiated thyroid carcinomas (DTCs) that arise from follicular cells account >90% of thyroid cancer (TC) [papillary thyroid cancer (PTC) 90%, follicular thyroid cancer (FTC) 10%], while medullary thyroid cancer (MTC) accounts <5%. Complete total thyroidectomy is the treatment of choice for PTC, FTC, and MTC. Radioiodine is routinely recommended in high-risk patients and considered in intermediate risk DTC patients. DTC cancer cells, during tumor progression, may lose the iodide uptake ability, becoming resistant to radioiodine, with a significant worsening of the prognosis. The lack of specific and effective drugs for aggressive and metastatic DTC and MTC leads to additional efforts toward the development of new drugs. Several genetic alterations in different molecular pathways in TC have been shown in the past few decades, associated with TC development and progression. Rearranged during transfection (RET)/PTC gene rearrangements, RET mutations, BRAF mutations, RAS mutations, and vascular endothelial growth factor receptor 2 angiogenesis pathways are some of the known pathways determinant in the development of TC. Tyrosine kinase inhibitors (TKIs) are small organic compounds inhibiting tyrosine kinases auto-phosphorylation and activation, most of them are multikinase inhibitors. TKIs act on the aforementioned molecular pathways involved in growth, angiogenesis, local, and distant spread of TC. TKIs are emerging as new therapies of aggressive TC, including DTC, MTC, and anaplastic thyroid cancer, being capable of inducing clinical responses and stabilization of disease. Vandetanib and cabozantinib have been approved for the treatment of MTC, while sorafenib and lenvatinib for DTC refractory to radioiodine. These drugs prolong median progression-free survival, but until now no significant increase has been observed on overall survival; side effects are common. New efforts are made to find new more effective and safe compounds and to personalize the therapy in each TC patient.