Virginia Cappagli

Treatment of advanced thyroid cancer with targeted therapies: ten years of experience

Thyroid cancer is rare, but it is the most frequent endocrine malignancy. Its prognosis is generally favorable, especially in cases of well-differentiated thyroid cancers (DTCs), such as papillary and follicular cancers, which have survival rates of approximately 95% at 40 years. However, 15-20% of cases became radioiodine refractory (RAI-R), and until now, no other treatments have been effective. The same problems are found in cases of poorly differentiated (PDTC) and anaplastic (ATC) thyroid cancers and in at least 30% of medullary thyroid cancer (MTC) cases, which are very aggressive and not sensitive to radioiodine. Tyrosine kinase inhibitors (TKIs) represent a new approach to the treatment of advanced cases of RAI-R DTC, MTC, PDTC, and, possibly, ATC. In the past 10 years, several TKIs have been tested for the treatment of advanced, progressive, and RAI-R thyroid tumors, and some of them have been recently approved for use in clinical practice: sorafenib and lenvatinib for DTC and PDTC and vandetanib and cabozantinib for MTC. The objective of this review is to present the current status of the treatment of advanced thyroid cancer with the use of innovative targeted therapies by describing both the benefits and the limits of their use based on the experiences reported so far. A comprehensive analysis and description of the molecular basis of these therapies, as well as new therapeutic perspectives, are reported. Some practical suggestions are given for both the choice of patients to be treated and their management, with particular regard to the potential side effects.

Cabozantinib (XL184) for the treatment of locally advanced or metastatic progressive medullary thyroid cancer

Cabozantinib (XL184) is an oral multiple receptor tyrosine kinase inhibitor manufactured by Exelixis Inc., CA, USA. It mainly inhibits three tyrosine kinase receptors: MET, VEGFR2 and RET. In both preclinical and clinical studies it has been shown to inhibit tumor angiogenesis, invasiveness and metastases. The most frequent side effects are fatigue, diarrhea, decreased appetite, nausea, weight loss and palmar-plantar erythrodysesthesia. A Phase III clinical trial (EXAM study) of XL184 versus placebo in advanced and progressive medullary thyroid cancer showed a 28 versus 0% overall response rate and a progression-free survival of 11.2 versus 4.0 months (hazard ratio: 0.28; 95% CI: 0.19-0.40; p < 0.0001) in patients treated with cabozantinib and placebo, respectively. The drug has been approved by the US FDA for the treatment of advanced/progressive metastatic medullary thyroid cancer in the USA. The EMA is now evaluating its approval in Europe.

In silico and in vitro analysis of rare germline allelic variants of RET oncogene associated with medullary thyroid cancer

Germline and somatic RET oncogene mutations are found in 98% hereditary and 40% sporadic medullary thyroid carcinomas. Our aim was to analyse by in silico and in vitro assays the transforming activity of six rare RET mutations (T338I, V648I, M918V, A883T, S904F and M848T). Six known RET mutations were used as controls. The in silico analysis showed the highest score value (i.e. 65) for S904F, M848T, M918T and C634R, whereas L790F, G691S, T338I and V648I had 0 score. Intermediate score values were obtained by A883T (score=55), M918V, V804M and Y791F (score=15). The in vitro focus formation assay showed that cells transfected with S904F, M918T, M848T or C634R generated the largest number of focus formation units (FFU). Intermediate numbers of FFU were observed in cells transfected with M918V, V804M, Y791F or A883T, while cells transfected with L790F, G691S, T338I or V648I showed a number of FFU similar to control cells. A positive correlation between the in silico score and in vitro FFU was found (P=0.0005). Only cells transfected with M918T or C634R grew faster and generated higher number of colonies in soft agar than control cells. However, the cells that were transfected with V804M produced an intermediate number of colonies. In conclusion, two of the six rare RET mutations, S904F and M848T possessed a relatively high transforming activity but a low aggressiveness; the other four mutations T338I, V648I, M918V and A883T were low or non-transforming, and their ability to induce tumoural transformation might be related to particular genetic conditions.

New insights in the molecular signature of advanced medullary thyroid cancer: evidence of a bad outcome of cases with double RET mutations

Background The RET proto-oncogene is responsible for the pathogenesis of hereditary (98%) and sporadic (40%) medullary thyroid carcinoma (MTC). In sporadic MTC, somatic RET mutations are associated with a poor prognosis. Objectives We looked at the genetic profile of patients with advanced and metastatic MTC. The correlation between these mutations and outcome was also investigated. Methods 70 patients with advanced and metastatic sporadic MTC were studied. Exons 10–11 and 13–16 of RET were analysed by direct sequencing. All cases were studied for RAS and the majority also for TERT mutations. RET/RAS-negative cases were analysed for other oncogene mutations. Results 64/70 cases (91.4%) showed a somatic mutation, while 6 (8.6%) were negative. Among the mutated cases, RET mutations, mainly M918T, were the most prevalent (93.8%). K- or H-RAS mutations were present in 6.2% of cases and were mutually exclusive with RET. No other mutations were found. Four tumours showed two RET somatic mutations. We found a complex somatic RET alteration in 6/60 (10%) RET-positive sporadic MTC cases. A positive correlation between a poor prognosis and the multiple number of RET mutations was found. Conclusions This study showed a high prevalence of somatic RET mutations in advanced and metastatic MTCs. RAS mutations were present in a small percentage of cases and mutually exclusive with RET mutations. In a small number of cases, more than one RET mutation was present in the same tissue. RET double mutations and, to a lesser extent, also complex mutations showed a worse outcome.

Calcitonin receptor expression in medullary thyroid carcinoma

Background Calcitonin expression is a well-established marker for medullary thyroid carcinoma (MTC); yet the role of calcitonin receptor (CTR), its seven-transmembrane G-protein coupled receptor, remains to be established in C-cells derived thyroid tumors. The aim of this work was to investigate CTR expression in MTC and to correlate such expression with clinicopathological features in order to evaluate its possible role as a prognostic indicator of disease aggressiveness and outcome. Methods Calcitonin receptor expression was analyzed in a series of 75 MTCs by immunohistochemistry, and by qPCR mRNA quantification in specimens from four patients. Statistical tests were used to evaluate the correlation between CTR expression and the clinicopathological and molecular characteristics of patients and tumors. Results Calcitonin receptor expression was detected in 62 out of 75 samples (82.7%), whereas 13 of the 75 samples (17.3%) were completely negative. CTR expression was significantly associated with expression of cytoplasmatic phosphatase and tensin homologue deleted on chromosome 10 and osteopontin, as well as with wild type RET/RAS genes and absence of tumor stroma, suggesting that CTR expression do not associate with clinicopathological signs of worse prognosis. Discussion Calcitonin receptor expression appears to be associated in MTC with more differentiated status of the neoplastic cells.

Protein kinase inhibitors for the treatment of advanced and progressive radiorefractory thyroid tumors: From the clinical trials to the real life

The last ten years have been characterized by the introduction in the clinical practice of new drugs named tyrosine kinase inhibitors for the treatment of several human tumors. After the positive conclusion of two international multicentric, randomized phase III clinical trials, two of these drugs, sorafenib and lenvatinib, have been recently approved and they are now available for the treatment of advanced and progressive radioiodine refractory thyroid tumors. We have been involved in most clinical trials performed with different tyrosine kinase inhibitors in different histotypes of thyroid cancer thus acquiring a lot of experience in the management of both drugs and their adverse events. Aim of this review is to give an overview of both the rationale for the use of these inhibitors in thyroid cancer and the major results of the clinical trials. Some suggestions for the management of treated patients in the real life are also provided.

Clinical Management of a Patient with a Locally Recurrent Medullary Thyroid Cancer and Asymptomatic Slowly Progressing Distant Metastases

We present the case of a young female patient affected by a sporadic medullary thyroid cancer (MTC) that, during the first 5 years of follow-up, recurred in the neck several times with no evidence of distant metastases. She was surgically treated 3 times during those years, and then she was apparently cured with undetectable levels of basal serum calcitonin (Ct). However, we knew that she was not completely cured since the serum stimulated Ct (i.e., 88 pg/ml) was suggestive of persistent disease. After about 6 years of undetectable basal levels of serum Ct, in 2005, also basal Ct become elevated (i.e., 21 pg/ml, normal values <14 pg/ml), and thereafter micrometastatic lesions were detected by computerized tomography in the lung and liver. For the next 5 years, the disease was stable with a very slow increase of serum Ct. In June 2009, new hepatic lesions were detected at CT scan, and one of them immediately started to grow with a median rate of 20 % of increase in size per year up to 2 cm in 2013, and since it was located very close to the gallbladder, it was decided to surgically remove it. The serum Ct dropped very rapidly, and after 1 year, it is stable, as are all the micrometastatic lesions in the lung and the liver. The patient is now 42 years old; her general health and quality of life are very good.

Cabozantinib: an orphan drug for thyroid cancer

Introduction: Until recently, no therapeutic options were available for the treatment of advanced medullary thyroid cancer (MTC). Cabozantinib (XL184) is a novel tyrosine kinase inhibitor (TKI) that inhibits several tyrosine kinase receptors, in particular those coded by MET, VEGFR-2 and RET oncogenes that are considered to be involved in the pathogenesis of MTC. Areas covered: This article provides an overview of the phase I and III trials that demonstrated the efficacy of cabozantinib in two cohorts of advanced MTC patients who were naïve or previously treated with other TKIs. The benefits in terms of progression-free survival (PFS), overall survival (OS) and the demographic clinical and mutational status of the two cohorts of MTC patients are reported and discussed. Expert opinion: The possibility to have a therapeutic option for the treatment of patients with advanced and progressive MTC and, in particular, the evidence that the drug can be active also in those patients who already experienced disease progression while taking another TKI is a great opportunity as demonstrated in cases treated with cabozantinib after vandetanib such as the one reported in this paper.

Clinical, pathological and genetic features of anaplastic and poorly differentiated thyroid cancer: A single institute experience

Anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC) are very aggressive cancers whose histological diagnosis is not always straightforward. Clinical, pathological and genetic features may be useful to improve the identification of these rare histotypes. In the present study the clinical, pathological and genetic features of two groups of ATC (n=21) and PDTC (n=21) patients were analyzed. Clinical data were retrieved from a computerized database. The oncogenic profiles were studied using the Sanger sequencing method of a selected series of oncogenes and/or tumor suppressor genes known to be altered in these tumors. The presence of macrophages in both series of tissues was evaluated by immunohistochemistry. Patients with ATC were older and affected by a more advanced disease at diagnosis than those with PDTC. The median survival was significantly shorter in ATC compared with PDTC patients (P=0.0014). ATC showed a higher prevalence of TP53 and TERT mutations (10/21, 47.6% and 9/21, 42.8%, respectively) while TERT and BRAF mutations were the most prevalent in the PDTC group (7/21, 33.3% and 4/23, 19% respectively). Genetic heterogeneity (i.e., >2 mutations) was more frequent in ATC (10/21, 28.6%) compared with in PDTC (3/21, 4.7%) (P=0.03). Macrophages were more frequently present in ATC, particularly in those cases with TP53 mutations. In conclusion, these data indicate that ATC and PDTC may be characterized by different clinical, pathological and genetic profiles. In particular ATC, but not PDTC, were positive for TP53 and PTEN alterations. Complex mutations were also found in ATC but not in PDTC. Moreover, genetic heterogeneity was more frequent in ATC than PDTC. Finally, TP53 mutation and the accumulation of several mutations correlated with a shorter survival time.

Il carcinoma tiroideo: nuove prospettive terapeutiche

SommarioLa maggior parte dei pazienti con carcinoma tiroideo guarisce con i trattamenti convenzionali (chirurgia e iodio radioattivo). Tuttavia, alcuni tumori tiroidei sono resistenti al radioiodio, perché perdono le caratteristiche della cellula follicolare da cui originano o perché originano dalle cellule C (carcinoma midollare della tiroide). Fino al 2011 nessuna terapia efficace era approvata per il trattamento di queste neoplasie. Di recente, una nuova classe di farmaci, gli inibitori tirosino-chinasici, che agiscono sul prodotto degli oncogeni che determinano lo sviluppo tumorale (es. BRAFV600E e RET) e sui recettori che favoriscono la proliferazione dell’endotelio vascolare (es. VEGFRs), ha offerto nuove prospettive terapeutiche per i pazienti con malattia avanzata e in progressione.