Advances in pharmacotherapy for advanced thyroid cancer of follicular origin (PTC, FTC). New approved drugs and future therapies.

INTRODUCTION: The most common altered signaling found in aggressive iodine-refractory thyroid cancers derived from follicular cells (RAI-TC) are RTK, MAPK, PI3K, WNT, BRAF, RAS, RET, and TP53. Tyrosine Kinase Inhibitors (TKI) are multi-kinase inhibitors able to act against different pathways, that elicit an anti-neoplastic activity. AREAS COVERED: The aim of this paper is to review recent novel molecular therapies of RAI-TC. Recently, sorafenib and lenvatinib, have been approved for the treatment of aggressive RAI-TC. Other studies are evaluating vandetanib and selumetinib in RAI-TC. Furthermore, preliminary studies have evaluated dabrafenib, and vemurafenib in BRAF mutated RAI-TC patients to re-induce 131-iodine uptake. The interplay between cells of the immune system and cancer cells can be altered by immune checkpoints inhibitors. The expression of PDL1 in RAI-TC was related to tumor recurrence and poor survival. Several clinical trials are investigating a combination of different therapies, such as lenvatinib and pembrolizumab. EXPERT OPINION: Mechanisms of resistance to TKIs inhibitors can be of intrinsic or acquired origin. An acquired resistance to lenvatinib, or sorafenib can be due to upregulation of FGFR; therefore, anti-FGFR agents are evaluated. A new strategy is to combine TKIs with immunotherapy. Several studies are evaluating lenvatinib and pembrolizumab in RAI-TC patients.

Protective Effects of Myo-Inositol and Selenium on Cadmium-Induced Thyroid Toxicity in Mice.

Cadmium (Cd) damages the thyroid gland. We evaluated the effects of myo-inositol (MI), seleno-L-methionine (Se) or their combination on the thyroids of mice simultaneously administered with Cd chloride (CdCl2). Eighty-four male mice were divided into 12 groups (seven mice each). Six groups (controls) were treated with 0.9% NaCl (vehicle), Se (0.2 mg/kg/day), Se (0.4 mg/kg/day), MI (360 mg/kg/day), MI+Se (0.2 mg/kg) and MI+Se (0.4 mg/kg). The other six groups were treated with CdCl2 (2 mg/kg), CdCl2+MI, CdCl2+Se (0.2 mg/kg), CdCl2+Se (0.4 mg/kg), CdCl2+MI+Se (0.2 mg/kg) and CdCl2+MI+Se (0.4 mg/kg). An additional group of CdCl2-challenged animals (n= 7) was treated with resveratrol (20 mg/kg), an effective and potent antioxidant. All treatments lasted 14 days. After sacrifice, the thyroids were evaluated histologically and immunohistochemically. CdCl2 reduced the follicular area, increased the epithelial height, stroma, and cells expressing monocyte chemoattractant protein-1 (MCP-1) and C-X-C motif chemokine 10 (CXCL10). CdCl2+Se at 0.2/0.4 mg/kg insignificantly reversed the follicular and stromal structure, and significantly decreased the number of MCP-1 and CXCL10-positive cells. CdCl2+MI significantly reversed the thyroid structure and further decreased the number of MCP-1 and CXCL10-positive cells. CdCl2+MI+Se, at both doses, brought all indices to those of CdCl2-untreated mice. MI, particularly in association with Se, defends mice from Cd-induced damage. The efficacy of this combination was greater than that of resveratrol, at least when using the follicular structure as a read-out for a comparison. We suggest that the use of these nutraceuticals, more specifically the combination of MI plus SE, can protect the thyroid of Cd-exposed subjects.

Nutraceuticals in Thyroidology: A Review of in Vitro, and in Vivo Animal Studies.

Nutraceuticals are defined as a food, or parts of a food, that provide medical or health benefits, including the prevention of different pathological conditions, and thyroid diseases, or the treatment of them. Nutraceuticals have a place in complementary medicines, being positioned in an area among food, food supplements, and pharmaceuticals. The market of certain nutraceuticals such as thyroid supplements has been growing in the last years. In addition, iodine is a fundamental micronutrient for thyroid function, but also other dietary components can have a key role in clinical thyroidology. Here, we have summarized the in vitro, and in vivo animal studies present in literature, focusing on the commonest nutraceuticals generally encountered in the clinical practice (such as carnitine, flavonoids, melatonin, omega-3, resveratrol, selenium, vitamins, zinc, and inositol), highlighting conflicting results. These experimental studies are expected to improve clinicians' knowledge about the main supplements being used, in order to clarify the potential risks or side effects and support patients in their use.

Endocrine disruptors and thyroid autoimmunity.

Many papers evaluated the effect of the environmental, or occupational endocrine disruptors (ED), on the thyroid gland, that can lead to thyroid autoimmunity. A higher prevalence of autoimmune thyroid diseases (AITD) was observed in people living in polluted areas near to petrochemical plants, and in petrochemical workers, but also in area contaminated with organochlorine pesticides, or with polychlorinated biphenyls, or near aluminum foundries. The exposure to Hg in chloralkali workers, or in swordfish consumers has been also found to increase AITD prevalence. Vanadium has been shown to increase the inflammatory response of thyrocytes. A beneficial effect of omega-3 fatty acids, and of myo-inositol and selenomethionine have been shown to counteract the appearance of AITD in subjects exposed to environmental or occupational ED. More large studies are needed to investigate the potential roles of ED in the induction of AITD, and of agents or habits that are able to prevent them.

Advancements in the treatment of hypothyroidism with L-T4 liquid formulation or soft gel capsule: an update.

INTRODUCTION: The most recent advance concerning levothyroxine (L-T4) therapy is the development of novel oral formulations: the liquid preparation, and the soft gel capsule. Areas covered: This review evaluates the most recent clinical studies about these new formulations. The liquid formulation has been shown to overcome: the food and beverages intereference with L-T4 tablets absorption, caused by food or coffee at breakfast; malabsorption induced by the increased gastric pH, resulting from atrophic gastritis, or due to proton-pump inhibitors; and malabsorption after bariatric surgery. The use of liquid L-T4 has been studied also in pregnancy, newborns and infants, suggesting a better bioequivalence than tablets. Finally, liquid L-T4 is more active than tablets in the control of thyroid-stimulating hormone (TSH) in hypothyroid patients without malabsorption, drug interference, or gastric disorders, leading to a hypothesized higher absorption of liquid L-T4 also in these patients. Few studies have evaluated soft gel L-T4 with promising results in patients with malabsorption related to coffee or gastritis. Expert opinion: Liquid L-T4 (and soft gel capsules) are more active than the tablet L-T4 in the control of TSH in hypothyroid patients with gastric disorders, malabsorption, or drug interference, but also in patients without absorption disorders.

Sorafenib in the treatment of thyroid cancer.

Sorafenib has been evaluated in several Phase II and III studies in patients with locally advanced/metastatic radioactive iodine-refractory differentiated thyroid carcinomas (DTCs), reporting partial responses, stabilization of the disease and improvement of progression-free survival. Best responses were observed in lung metastases and minimal responses in bone lesions. On the basis of these studies, sorafenib was approved for the treatment of metastatic DTC in November 2013. Few studies suggested that reduction of thyroglobulin levels, or of average standardized uptake value at the fluorodeoxyglucose-PET, could be helpful for the identification of responding patients; but further studies are needed to confirm these results. Tumor genetic marker levels did not have any prognostic or predictive role in DTC patients.The most common adverse events observed included skin toxicity and gastrointestinal and constitutional symptoms. Encouraging results have also been observed in patients with medullary thyroid cancer. Many studies are ongoing to evaluate the long-term efficacy and tolerability of sorafenib in DTC patients.

Sorafenib and thyroid cancer.

Sorafenib (Nexavar) is a multikinase inhibitor, which has demonstrated both anti-proliferative and anti-angiogenic properties in vitro and in vivo, inhibiting the activity of targets present in the tumor cell [c-RAF (proto-oncogene serine/threonine-protein kinase), BRAF, (V600E)BRAF, c-KIT, and FMS-like tyrosine kinase 3] and in tumor vessels (c-RAF, vascular endothelial growth factor receptor-2, vascular endothelial growth factor receptor-3, and platelet-derived growth factor receptor ß). For several years, sorafenib has been approved for the treatment of hepatocellular carcinoma and advanced renal cell carcinoma. After previous studies showing that sorafenib was able to inhibit oncogenic RET mutants, (V600E)BRAF, and angiogenesis and growth of orthotopic anaplastic thyroid cancer xenografts in nude mice, some clinical trials demonstrated the effectiveness of sorafenib in advanced thyroid cancer. Currently, the evaluation of the clinical safety and efficacy of sorafenib for the treatment of advanced thyroid cancer is ongoing. This article reviews the anti-neoplastic effect of sorafenib in thyroid cancer. Several completed (or ongoing) studies have evaluated the long-term efficacy and tolerability of sorafenib in patients with papillary and medullary aggressive thyroid cancer. The results suggest that sorafenib is a promising therapeutic option in patients with advanced thyroid cancer that is not responsive to traditional therapeutic strategies.

Evaluation of the sensitivity to chemotherapeutics or thiazolidinediones of primary anaplastic thyroid cancer cells obtained by fine-needle aspiration.

OBJECTIVE: Anaplastic thyroid cancer (ATC) is often unoperable and chemotherapy and radiotherapy are the main treatments. Until now 'primary ATC cell cultures' (ANA) have been developed from surgical biopsies. The possibility to obtain ANA from fine-needle aspiration (FNA-ANA) and to test their sensitivity to different drugs could increase the effectiveness of treatments and avoid unnecessary surgical procedures. DESIGN: To obtain FNA-ANA from six ATC patients before undergoing surgery and to evaluate the chemosensitivity of FNA-ANA to chemotherapeutic agents and thiazolidinediones (TZD). METHODS AND RESULTS: FNA-ANA from the six ATC patients were cultured in RPMI 1640 and propagated in DMEM. Chemosensitivity was evaluated by inhibiting the proliferation with increasing concentrations of five different chemotherapeutic agents (bleomycin, cisplatin, gemcitabine, etoposide, and carboplatin) or TZD (rosiglitazone). Chemotherapeutic agents significantly inhibited (P<0.0001) FNA-ANA proliferation, such as TZD (P<0.001); etoposide was the most effective in reducing cell growth. Another ANA culture for each patient was obtained from a biopsy specimen; the results for the chemosensitivity tests were similar to those obtained with FNA-ANA. The (V600E)BRAF mutation was observed in two ATC patients; the inhibition of proliferation by drugs was similar in tumors with or without (V600E)BRAF mutation. CONCLUSIONS: Our study demonstrates 1) the possibility to obtain FNA-ANA, and opens the way to the use of FNA-ANA to test the chemosensitivity to different drugs (chemotherapeutic agents or TZD; and possibly the radiosensitivity) in each patient, avoiding unnecessary surgical procedures and the administration of inactive chemotherapeutics; and 2) that etoposide is highly effective in reducing ATC cell growth in vitro.