Phase II study of celecoxib in metastatic differentiated thyroid carcinoma

Targeting Non-Oncogene Addiction: Focus on Thyroid Cancer

Thyroid carcinoma (TC) is the most common malignancy of endocrine organs with an increasing incidence in industrialized countries. The majority of TC are characterized by a good prognosis, even though cases with aggressive forms not cured by standard therapies are also present. Moreover, target therapies have led to low rates of partial response and prompted the emergence of resistance, indicating that new therapies are needed. In this review, we summarize current literature about the non-oncogene addiction (NOA) concept, which indicates that cancer cells, at variance with normal cells, rely on the activity of genes, usually not mutated or aberrantly expressed, essential for coping with the transformed phenotype. We highlight the potential of non-oncogenes as a point of intervention for cancer therapy in general, and present evidence for new putative non-oncogenes that are essential for TC survival and that may constitute attractive new therapeutic targets.

IL-12 immunotherapy of Braf(V600E)-induced papillary thyroid cancer in a mouse model

Papillary thyroid carcinoma (PTC) accounts for >80% thyroid malignancies, and BRAF(V600E) mutation is frequently found in >40% PTC. Interleukin-12 (IL-12) is a proinflammatory heterodimeric cytokine with strong antitumor activity. It is not known whether IL-12 immunotherapy is effective against Braf(V600E)-induced PTC. In the present study, we investigated the effectiveness of IL-12 immunotherapy against Braf(V600E)-induced PTC in LSL-Braf(V600E)/TPO-Cre mice. LSL-Braf(V600E)/TPO-Cre mice were created for thyroid-specific expression of Braf(V600E) under the endogenous Braf promoter, and spontaneous PTC developed at about 5 weeks of age. The mice were subjected to two treatment regimens: (1) weekly intramuscular injection of 50 μg plasmid DNA expressing a single-chain IL-12 fusion protein (scIL-12/CMVpDNA), (2) daily intraperitoneal injection of mouse recombinant IL-12 protein (mrIL-12, 100 ng per day). The role of T cells, natural killer (NK) cells, and transforming growth factor-β (TGF-β) in IL-12-mediated antitumor effects was determined by a (51)Cr-release cytotoxicity assay. Tumor size and weight were significantly reduced by either weekly intramuscular injection of scIL-12/CMVpDNA or daily intraperitoneal injection of mrIL-12, and tumor became more localized. Survival was significantly increased when treatment started at 1 week of age as compared with that at the 6 weeks of age. Both NK and CD8(+) T cells were involved in the cytotoxicity against tumor cells and their antitumor activity was significantly reduced in tumor-bearing mice. TGF-β also inhibited the antitumor activity of NK and CD8(+) T cells. The immune suppression was completely reversed by IL-12 treatment and partially recovered by anti-TGF-β antibody. We conclude that both IL-12 gene therapy and recombinant protein therapy are effective against PTC. Given that the immune response is significantly suppressed in tumor-bearing mice and can be restored by IL-12, the current study raises a possibility of the application of IL-12 as an adjuvant therapy for thyroid cancer.

Molecular pathogenesis and targeted therapies in well-differentiated thyroid carcinoma

Four proto-oncogenes commonly associated with well-differentiated thyroid carcinoma, rearranged during transfection (RET)/papillary thyroid cancer, BRAF, RAS, and PAX8/peroxisome proliferator activated receptor-γ, may carry diagnostic and prognostic significance. These oncogenes can be used to improve the diagnosis and management of well-differentiated thyroid carcinoma. Limited therapeutic options are available for patients with metastatic well-differentiated thyroid cancer, necessitating the development of novel therapies. Vascular endothelial growth factor (VEGF)- and RET-directed therapies such as sorafenib, motesanib, and sunitinib have been shown to be the most effective at inducing clinical responses and stabilizing the disease process. Further clinical trials of these therapeutic agents may soon change the management of thyroid cancer.

Medical therapy for advanced forms of thyroid cancer

More options than ever before are currently available for medical therapy in patients who present with advanced thyroid cancer or develop surgically unresectable recurrences or symptomatic or progressive disease. The newer medical therapies have addressed the need to find effective therapies beyond the conventional treatment with radioactive iodine, thyroid stimulating hormone suppression, and palliative cytotoxic chemotherapy for patients with advanced thyroid cancer. Although tumor responses to these medical therapies vary by type of thyroid cancer and type of therapy selected, they remain encouraging and provide therapeutic options for selected patients while new drugs are in development.

Advanced thyroid cancers: new era of treatment

Since chemotherapy has been shown to be unsuccessful in case of advanced thyroid carcinomas, the research for new therapies is fundamental. Clinical trials of many tyrosine kinase inhibitors as well as anti-angiogenic inhibitors suggest that patients with thyroid cancer could have an advantage with new target therapy. Recently, Food and Drug Administration approved two targeted therapies, vandetanib and cabozantinib for the treatment of metastatic thyroid carcinomas with acceptable outcome. We summarized the results and the toxic effects associated with these treatments reported in clinical trials. Future trials should aim at combinations of targeted agents with or without other treatment modalities to obtain a more effective result in thyroid carcinoma treatment.

Sorafenib in the treatment of radioiodine-refractory differentiated thyroid cancer: a meta-analysis

The advent of biologically targeted agents and increased understanding of thyroid carcinogenesis have generated much interest in the development of biologically targeted therapeutic agents for thyroid cancer. Among them, sorafenib is the most commonly studied drug. The current meta-analysis was carried out to estimate the efficacy and safety of sorafenib administered in radioiodine-refractory differentiated thyroid cancer patients. An electronic search was conducted using PubMed/MEDLINE and EMBASE. Statistical analyses were carried out using either random-effects or fixed-effects models according to heterogeneity. All the statistical analyses were carried out using the Stata version 12.0 software. Seven eligible studies were identified. The final results indicated that 22% of the patients (95% CI: 15-28) achieved a partial response. Hand-foot syndrome, diarrhea, fatigue, rash, weight loss, and hypertension were the most frequently observed adverse effects (AEs) associated with sorafenib use and the incidence of these AEs (all grades) was 80% (95% CI: 68-91), 68% (95% CI: 59-77), 67% (95% CI: 57-78), 66% (95% CI: 50-82), 52%(95% CI: 33-72), and 31% (95% CI: 21-42) respectively. Sixty-two percent (95% CI: 36-89) patients required dose reductions due to toxicity of sorafenib. As far as PR and AEs are concerned, the results of this meta-analysis indicate that sorafenib has a modest effect in patients with radioiodine-refractory differentiated thyroid cancer and the high incidence of AEs associated with this agent may affect the quality of patients' lives. Though the use of sorafenib in the treatment of radioiodine-refractory differentiated thyroid cancer is considered promising by most physicians working in this field, more effective agents with less toxicity and cost are still needed.

New therapeutic options for advanced forms of thyroid cancer

INTRODUCTION

While the vast majority of patients with thyroid cancer have an excellent prognosis, those with more aggressive courses experience significant morbidity and mortality. Advanced forms of thyroid cancer are typically refractory to standard therapy. Numerous agents with potential usefulness in the treatment of advanced thyroid cancer have recently come under study.

AREAS COVERED

This article reviews agents identified through a systematic review of the scientific literature as being under investigation for treatment of advanced thyroid cancer. A search of both PubMed and the NCI Clinical Trials website was performed to identify such agents having reached Phase II or III testing. Improved understanding of cancer cell signaling pathways has led to the identification of > 500 kinases as potential therapeutic targets. Additional agents of interest include those that inhibit neoangiogenesis, alter epigenetic factors or stimulate antitumor immune reactions. While presently available agents have shown promise in improving progression-free survival (PFS), complete responses are not seen and significant adverse side effects are encountered.

EXPERT OPINION

The development of numerous new anticancer agents holds the promise of treatment regimens that will extend PFS and ultimately overall survival in patients with advanced thyroid cancer. Anticipated future developments include individualized, multimodal treatment regimens based on specific tumor cell biology and driver mutations.

Multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma: an update

CONTEXT

Over the last decade, our knowledge of the multiple endocrine neoplasia (MEN) type 2 syndromes MEN2A and MEN2B and familial medullary thyroid carcinoma (FMTC) has expanded greatly. In this manuscript, we summarize how recent discoveries have enhanced our understanding of the molecular basis of these diseases and led to improvements in the diagnosis and management of affected patients.

EVIDENCE ACQUISITION

We reviewed the English literature through PubMed from 2000 to the present, using the search terms medullary thyroid carcinoma, multiple endocrine neoplasia type 2, familial medullary thyroid carcinoma, RET proto-oncogene, and calcitonin.

EVIDENCE SYNTHESIS

Over 70 RET mutations are known to cause MEN2A, MEN2B, or FMTC, and recent findings from studies of large kindreds with these syndromes have clouded the relationship between genotype and phenotype, primarily because of the varied clinical presentation of different families with the same RET mutation. This clinical variability has also confounded decisions about the timing of prophylactic thyroidectomy for MTC, the dominant endocrinopathy associated with these syndromes. A distinct advance has been the demonstration through phase II and phase III clinical trials that molecular targeted therapeutics are effective in the treatment of patients with locally advanced or metastatic MTC.

CONCLUSIONS

The effective management of patients with MEN2A, MEN2A, and FMTC depends on an understanding of the variable behavior of disease expression in patients with a specific RET mutation. Information gained from molecular testing, biochemical analysis, and clinical evaluation is important in providing effective management of patients with either early or advanced-stage MTC.

Clinical, safety, and economic evidence in radioactive iodine-refractory differentiated thyroid cancer: a systematic literature review

BACKGROUND

Thyroid cancer is the most common endocrine malignancy, with differentiated thyroid cancer (DTC) comprising ~93% of all thyroid cancers. While most cases of DTC are curable with the use of surgery and radioactive iodine (RAI) ablation of the remaining thyroid remnant, prognosis is dire and treatment options limited when DTC becomes RAI-refractory (RAI-R). Standard cytotoxic chemotherapy has limited efficacy, making enrollment in clinical trials of novel targeted therapies the preferred treatment approach. Thus, we conducted a comprehensive systematic review of the clinical trial scientific literature with a focus on efficacy, safety, and economics to identify all potential treatment options that have been or are currently being evaluated for the treatment of RAI-R DTC.

METHODS

Embase.com (including Medline), Medline In-Process and other nonindexed citations, the Cochrane Libraries, ClinicalTrials.gov, and relevant recent conference proceedings were searched using predefined search criteria. Important inclusion criteria included English language, randomized controlled studies or interventional single-arm studies only, and studies of drug therapies only. Search results were screened utilizing the discretion of multiple researchers, and key data were abstracted.

RESULTS

Forty-five unique trials (16 full-text, 4 conference abstracts, and 25 ClinicalTrials.gov entries) were included in the clinical review. No studies that met criteria for inclusion in the economic review were identified. Among 20 trials with results available, all were Phase II and only one was randomized. The most commonly studied drugs were tyrosine kinase inhibitors (TKIs); other drugs included celecoxib, doxorubicin with interferon alpha-2b, rosiglitazone, selumetinib (AZD6244), thalidomide, VEGF trap, and vorinostat. Overall, efficacy and safety profiles were specific to treatment regimen, with objective response rates (ORR) ranging from 0% on gefitinib, rosiglitazone, VEGF trap, and vorinostat to 50% on lenvatinib, a TKI.

CONCLUSIONS

Limited clinical research and no economic research has been conducted in RAI-R DTC. Certain treatments, notably TKIs, have shown promise in Phase II trials, and two Phase III randomized placebo-controlled trials are ongoing. New research on the economic and humanistic burden of RAI-R DTC must be paired with the clinical evidence currently in development to examine the existing burden and future promise in treating patients with RAI-R DTC.

New insight into the treatment of advanced differentiated thyroid cancer

The vast majority of patients with differentiated thyroid cancer (DTC) are treated successfully with surgery and radioactive iodine ablation, yet the treatment of advanced cases is frustrating and largely ineffective. Systemic treatment with conventional cytotoxic chemotherapy is basically ineffective in most patients with advanced DTC. However, a better understanding of the genetics and biologic basis of thyroid cancers has generated opportunities for innovative therapeutic modalities, resulting in several clinical trials. We aim to delineate the latest knowledge regarding the biologic characteristics of DTC and to describe the available data related to novel targeted therapies that have demonstrated clinical effectiveness.

Differentiated thyroid cancers: a comprehensive review of novel targeted therapies

Differentiated thyroid carcinoma (DTC) accounts for more than 90% of new thyroid cancer diagnoses, and includes papillary, follicular and Hürthle cell carcinoma. The prognosis for the vast majority of individuals diagnosed with DTC is excellent, with current treatment that includes surgery, radioactive iodine ablation and postoperative thyroid-stimulating hormone suppression. Unfortunately, the small proportion of individuals who develop radioactive iodine-resistant recurrent disease have few treatment options, and the vast majority will eventually die from their disease. Recently, several novel targets for anticancer agents have been identified and offer new hope for thyroid cancer patients diagnosed with progressive disease. In addition to targeting genes commonly altered in thyroid cancer, which include mutations in BRAF, RAS and RET, proangiogenic growth factor receptors and the sodium-iodide symporter have also been targeted. Several clinical trials evaluating tyrosine kinase and angiogenesis inhibitors for treatment of individuals diagnosed with metastatic or treatment-refractory DTC are currently underway. The objective of this review is to evaluate recent clinical trials that have studied novel targeted drugs for treatment of DTC.

Detection of Survivin and COX-2 in Thyroid Carcinoma: Anaplastic Carcinoma Shows Overexpression of Nuclear Survivin and Low COX-2 Expression

BACKGROUND

Overexpression of survivin, a member of the inhibitors of apoptosis protein, has been reported in various carcinomas, and its interaction with cyclooxygenase 2 (COX-2) results in accelerated tumor progression. The purpose of this study is to investigate the immunohistochemical expression of survivin and COX-2 in benign and malignant thyroid tissues and to define its association with pathologic and clinical features.

METHODS

We examined expression of survivin and COX-2 by immunohistochemistry in 334 benign and malignant thyroid tissues and evaluated their clinical significance.

RESULTS

Expression of survivin showed an increase along the spectrum of thyroid carcinoma progression; rarely positive in adenomatous goiter, moderately positive in papillary carcinoma, and strongly positive in anaplastic carcinoma (AC). Papillary microcarcinoma revealed the highest COX-2 positivity and AC demonstrated the lowest positivity among thyroid cancers. Node negative carcinomas showed higher COX-2 expression than node positive tumors. Survivin expression did not correlate with COX-2.

CONCLUSIONS

Our findings suggest that survivin overexpression may be related to the pathogenesis of AC and can be a predictor of disease progression. COX-2 may be involved in the early phase of thyroid carcinoma.

New treatment modalities in advanced thyroid cancer

BACKGROUND

Thyroid cancer is a heterogeneous disease that is classified into differentiated thyroid carcinoma (DTC), undifferentiated/anaplastic thyroid carcinoma (ATC) and medullary thyroid carcinoma. Results of conventional treatment modalities in advanced thyroid cancer have been disappointing and therefore, new therapies are needed.

METHODS

We searched PubMed, The Cochrane Library, Medline and EMBASE databases and abstracts published in annual proceedings for new treatment modalities in advanced thyroid cancer. We also searched for ongoing trials in www.clinicaltrials.gov.

RESULTS

Six phase I, 17 phase II and 1 phase III trials with tyrosine kinase inhibitors were carried out. We found 2 pilot studies and 11 phase II trials with redifferentiation therapies, mainly in DTC. For antiproliferative approaches, three phase I and four phase II trials were found. Immunomodulatory gene therapy was tested in a pilot study in ATC patients. Two phase II trials were carried out with immunotherapy. One phase I and nine phase II trials were found with radionucleotide therapy in patients with DTC.

CONCLUSION

The developments in the treatment of advanced thyroid cancer are intriguing. Future trials should aim at combinations of targeted agents with or without other treatment modalities, and will hopefully contribute to further improvement of outcomes.

Thyroid cancer: emerging role for targeted therapies

The histology and clinical behavior of thyroid cancer are highly diverse. Although most are indolent tumors with a very favorable outcome with the current standard of care therapy, a small subset of tumors may be among the most lethal malignancies known to man. While surgery and radioactive iodine are the standard of care for differentiated thyroid cancers (DTC) and are effective in curing a majority of such patients, those with iodine-resistant cancers pose a great challenge for clinicians, as these patients have limited treatment options and poor prognoses. Medullary thyroid carcinoma (MTC) has no effective systemic therapy despite the genetic and signaling defects that have been well characterized for the last two decades. Anaplastic thyroid cancer (ATC) is one of the most aggressive solid tumors that remains fatal despite conventional multimodality therapy. Increased understanding of the pathogenesis of papillary thyroid carcinoma, the most common type of DTC, as well as ATC, has led to the development of targeted therapies aimed at signaling pathways and angiogenesis that are critical to the development and/or progression of such tumors. Development of tyrosine kinase inhibitors targeting known pathogenetic defects in MTC has led to testing of such agents in the clinic. Numerous clinical trials have been conducted over the last 5 years to examine the effects of these targeted molecular therapies on the outcomes of patients with iodine-refractory DTC, MTC and ATC. Conduction of such trials in the last few years represents a major breakthrough in the field of thyroid cancer. Several trials testing targeted therapies offer promise for setting new standards for the future of patients with progressive thyroid cancer. The purpose of this paper is to outline the recent advances in understanding of the pathogenesis of thyroid cancer and to summarize the results of the clinical trials with these targeted therapies.

FOXO3 is inhibited by oncogenic PI3K/Akt signaling but can be reactivated by the NSAID sulindac sulfide

BACKGROUND

Overactivation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway has emerged as a pivotal trigger of thyroid carcinogenesis. Recent findings from other tumor entities revealed that PI3K/Akt-driven carcinogenesis critically involves the inactivation of the tumor-suppressive transcription factor Forkhead box O (FOXO)-3. However, little is known about FOXO3 in the thyroid context.

AIMS

We sought to investigate the influence of the thyroid oncogenes BRAFV600E, H-RASV12, and p110α (H1074R) on the regulation of the PI3K downstream target FOXO3 in vitro. Furthermore, the impact of the expression of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) on the transcriptional activity of FOXO3 was assessed in a panel of 44 human thyroid tumors. Finally, we tried to modulate FOXO3 activity pharmacologically with help of the nonsteroidal antiinflammatory drug sulindac sulfide (SS).

RESULTS

We found that the overexpression of p110α H1074R results in the inactivation of FOXO3 via its nuclear exclusion. In vivo, we observed a direct correlation between PTEN expression and the transcriptional activation of FOXO3. In vitro, we found that stimulation with SS reversed PI3K/Akt-driven inactivation of FOXO3, resulting in its nuclear relocation and a combined induction of the antiproliferative FOXO target genes Gadd45α and p27(kip1) and the proapoptotic FOXO target gene Bim in benign (FRTL-5) and malignant human thyrocytes (FTC-133). In agreement with this, SS promoted the cell cycle arrest and apoptosis in thyroid cells, which could be amplified by the transfection of exogenous FOXO3.

CONCLUSION

Our data suggest that deregulation of proapoptotic FOXO3 represents a central step in PI3K/Akt-mediated thyroid carcinogenesis. Thus, SS might represent an attractive pharmacological tool for targeting thyroid neoplasia with aberrant PI3K/Akt/FOXO3 signaling.

Efficacy of pazopanib in progressive, radioiodine-refractory, metastatic differentiated thyroid cancers: results of a phase 2 consortium study

BACKGROUND

Chemotherapy has historically proven ineffective in advanced differentiated thyroid cancers, but the realisation that various tyrosine kinases are activated in the disease suggested a potential therapeutic role for tyrosine-kinase inhibitors. We investigated the safety and efficacy of pazopanib.

METHODS

This phase 2 trial was done from Feb 22, 2008, to Jan 31, 2009, in patients with metastatic, rapidly progressive, radioiodine-refractory differentiated thyroid cancers. Each patient received 800 mg continuous pazopanib daily in 4-week cycles until disease progression, drug intolerance, or both occurred. Up to two previous therapies were allowed, and measurable disease with radiographic progression in the 6-month period before enrolment was a requirement for inclusion. The primary endpoint was any tumour response, according to the Response Evaluation Criteria in Solid Tumors 1.0. This study is registered with ClinicalTrials.gov, number NCT00625846.

FINDINGS

39 patients were enrolled. One patient had received no previous radioiodine therapy and another withdrew consent before treatment. Clinical outcomes could, therefore, be assessed in 37 patients (19 [51%] men, median age 63 years). The study is closed to accrual of new patients, but several enrolled patients are still being treated. Patients received a median of 12 cycles (range 1 to >23, total >383). Confirmed partial responses were recorded in 18 patients (response rate 49%, 95% CI 35-68), with likelihood of response lasting longer than 1 year calculated to be 66%. Maximum concentration of pazopanib in plasma during cycle one was significantly correlated with radiographic response (r=-0·40, p=0·021). 16 (43%) patients required dose reductions owing to adverse events, the most frequent of which (any grade) were fatigue (29 patients), skin and hair hypopigmentation (28), diarrhoea (27), and nausea (27). Two patients who died during treatment had pre-existing contributory disorders.

INTERPRETATION

Pazopanib seems to represent a promising therapeutic option for patients with advanced differentiated thyroid cancers. The correlation of the patient's response and pazopanib concentration during the first cycle might indicate that treatment can be individualised to achieve optimum outcomes. Assessment of pazopanib in an expanded cohort of patients with differentiated thyroid cancer, as well as in cohorts of patients with medullary and anaplastic thyroid cancers, is presently being done.

FUNDING

National Cancer Institute, supported in part by NCI CA15083 and CM62205.

Update on recent developments in the therapy of differentiated thyroid cancer

In the past decade, the management of differentiated thyroid carcinoma changed significantly and thus contributed to the improvement of the already favorable prognosis of this malignant disease. Surgical treatment techniques improved and the extent of initial surgery is more individualized. Radioiodine therapy is an essential part of therapeutic regimens in almost all cases, and the use of recombinant human thyroid-stimulating hormone has established for ablation of remnant tissue, treatment of iodine-positive cancer, and sensitive thyroglobulin measurement during follow-up. Risk stratification has become more important to plan treatment and follow-up individually, particularly to evaluate the need for thyroid-stimulating hormone suppression therapy. Especially for inoperable and radioiodine-negative thyroid carcinomas, novel treatment options such as tyrosine kinase inhibitor therapy have emerged. This article deals with the current options of optimal therapy regimens in differentiated thyroid carcinoma.

Sulindac reverses aberrant expression and localization of beta-catenin in papillary thyroid cancer cells with the BRAFV600E mutation

BACKGROUND

Activation of the Wnt/beta-catenin signaling pathway is implicated in thyroid tumorigenesis, and up to 90% of papillary thyroid cancer (PTC) demonstrate aberrant expression of beta-catenin. Nonsteroidal antiinflammatory drugs reverse aberrant beta-catenin expression and localization in colon cancer. In this study, we tested the hypothesis that the nonsteroidal antiinflammatory drug sulindac would reverse aberrant beta-catenin activity in thyroid cancer cells.

METHODS

beta-catenin protein levels were determined in thyroidectomy specimens from six consecutive patients and in three different thyroid cancer cells lines (8505-C, KTC-1, and TPC-1) by immunoblotting. Cells of 8505-C and KTC-1 harbor the BRAF(V600E) mutation, and TPC-1 has the RET/PTC rearrangement. All cell lines were treated with sulindac (100 microM for up to 72 hours). Protein levels of c-myc and cyclin D1 were detected by immunoblotting, and beta-catenin localization was determined by immunocytochemistry in the PTC cell lines. PCCL3 rat thyroid cells that conditionally overexpress either BRAF(V600E) or RET/PTC were also treated with sulindac.

RESULTS

All PTC specimens and cell lines expressed high levels of beta-catenin protein and displayed aberrant nuclear and cytoplasmic localization of beta-catenin. Exposure to sulindac for 48 hours reduced beta-catenin expression in 8505-C and KTC-1 cells, but not in TPC-1 cells. Further, sulindac treatment reduced c-myc and cyclin D1 levels in 8505-C and KTC-1 cells, but had no effect in TPC-1 cells. Immunocytochemistry demonstrated that sulindac treatment redistributed beta-catenin from the nucleus to the membrane in 8505-C and KTC-1 cells. However, sulindac did not affect beta-catenin localization in TPC-1 cells. Finally, sulindac was effective in decreasing beta-catenin expression and cellular proliferation in BRAF(V600E)-overexpressing cells, but not in RET/PTC3-overexpressing cells.

CONCLUSIONS

Taken together, our findings demonstrate that sulindac treatment reverses beta-catenin activity in 8505-C and KTC-1 cell lines with the BRAF(V600E), but not in TPC-1 cells with the RET/PTC mutation. Future studies should investigate the potential for beta-catenin-directed therapy for patients with advanced thyroid cancers.

Targeted therapy of thyroid cancer

Systemic chemotherapies for advanced or metastatic thyroid carcinomas have been of only limited effectiveness. For patients with differentiated or medullary carcinomas unresponsive to conventional treatments, novel therapies are needed to improve disease outcomes. Multiple novel therapies primarily targeting angiogenesis have entered clinical trials for metastatic thyroid carcinoma. Partial response rates up to 30% have been reported in single agent studies, but prolonged disease stabilization is more commonly seen. The most successful agents target the vascular endothelial growth factor receptors, with potential targets including the mutant kinases associated with papillary and medullary oncogenesis. Two drugs approved for other malignancies, sorafenib and sunitinib, have had promising preliminary results reported, and are being used selectively for patients who do not qualify for clinical trials. Additional agents targeting tumor vasculature, nuclear receptors, epigenetic abnormalities, and the immune response to neoplasia have also been investigated. Randomized trials for several agents are underway that may lead to eventual drug approval for thyroid cancer. Treatment for patients with metastatic or advanced thyroid carcinoma now emphasizes clinical trial opportunities for novel agents with considerable promise. Alternative options now exist for use of tyrosine kinase inhibitors that are well tolerated and may prove worthy of regulatory approval for this disease.

Old and new insights in the treatment of thyroid carcinoma

Thyroid cancer is the endocrine tumor that bears the highest incidence with 33 550 new cases per year. It bears an excellent prognosis with a mortality of 1530 patients per year (Jemal et al.; 2007). We have been treating patients with thyroid carcinoma during many years without many innovations. Recently, we have assisted to the development of new agents for the treatment of this disease with unexpected good results. Here we present a review with the old and new methods for the treatment of this disease.

Standard and emerging therapies for metastatic differentiated thyroid cancer

Differentiated thyroid cancer accounts for >90% of cases of thyroid cancer, with most patients having an excellent prognosis. Distant metastases occur in 10%-15% of patients, decreasing the overall 10-year survival rate in this group to 40%. Radioactive iodine has been the mainstay of treatment for distant metastases, with good results when lesions retain the ability to take up iodine. For patients with metastatic disease resistant to radioactive iodine, treatment options are few and survival is poor. Chemotherapy and external beam radiotherapy have been used in these patients, but with disappointing results. In recent years, our understanding of the molecular pathways involved in thyroid cancer has increased and a number of molecular targets have been identified. These targets include the proto-oncogenes BRAF and RET, known to be common mutations in thyroid cancer; vascular endothelial growth factor receptor and platelet-derived growth factor receptor, associated with angiogenesis; and the sodium-iodide symporter, with the aim of restoring its expression and hence radioactive iodine uptake. There are now multiple trials of tyrosine kinase inhibitors, angiogenesis inhibitors, and other novel agents available to patients with metastatic thyroid cancer. This review discusses both traditional and novel treatments for metastatic differentiated thyroid cancer with a particular focus on emerging treatments for patients with radioactive iodine-refractory disease.

Novel treatment of medullary thyroid cancer

PURPOSE OF REVIEW

Metastatic medullary thyroid cancer (MTC) is an incurable disease once metastasis becomes unresectable. Many therapeutic drugs and methods have been tried to circumvent this difficulty. We review currently published treatments and hope for future developments of more effective treatment methods.

RECENT FINDINGS

Motesanib, vandetanib, axitinib (tyrosine kinase inhibitors), and XL184 (multikinase inhibitor) have been shown to achieve partial response or stable disease state of metastatic MTC. Sunitinib and sorafenib, currently available tyrosine kinase inhibitors, can also be tried for patients with MTC. However, these medications are not curative and do not improve survival rate. Only carcinoembryonic antigen-I-iodine-based radioimmunotherapy improved survival of a subset of patients with a very aggressive type of MTC. Drugs currently available for possible use of MTC treatment include bortezomib (proteasome inhibitor), valproic acid (histone deacetylase inhibitor), capecitabine (5-fluorouracil prodrug), and indomethacin (NSAID), although clinical studies have yet to be done. Cardiac natriuretic hormones and an extract of the plant Cautleya gracilis are new agents to be studied for MTC.

SUMMARY

Kinase inhibitors are the first drugs showing some efficacy in MTC. To improve survival, unconventional drugs or other therapies with or without kinase inhibitors need to be considered.

[(90)Yttrium-DOTA]-TOC response is associated with survival benefit in iodine-refractory thyroid cancer: long-term results of a phase 2 clinical trial

BACKGROUND

The authors aimed to explore the efficacy of (90)Yttrium-1,4,7,10-tetra-azacyclododecane N,N',N'',N'''-tetraacetic acid [(90)Y-DOTA]-Tyr(3)-octreotide (TOC) in advanced iodine-refractory thyroid cancer.

METHODS

In a phase 2 trial, the authors investigated biochemical response (assessed by serum thyroglobulin levels), survival, and the long-term safety profile of systemic [(90)Y-DOTA]-TOC treatment in metastasized iodine-refractory thyroid cancer. Adverse events were assessed according to the National Cancer Institute criteria. Survival analyses were performed by using multiple regression models.

RESULTS

A total of 24 patients were enrolled. A median cumulative activity of 13.0 GBq (range, 1.7-30.3 GBq) was administered. Response was found in 7 (29.2%) patients. Eight (33.3%) patients developed hematologic toxicity grade 1-3, and 4 (16.7%) patients developed renal toxicity grade 1-4. The median survival was 33.4 months (range, 3.6-126.8 months) from time of diagnosis and 16.8 months (range, 1.8-99.1 months) from time of first [(90)Y-DOTA]-TOC treatment. Response to treatment was associated with longer survival from time of diagnosis (hazard ratio [HR], 0.17; 95% confidence interval [CI], 0.03-0.92; P = .04) and from time of first [(90)Y-DOTA]-TOC therapy (HR, 0.20; 95% CI, 0.04-0.94; P = .04). The visual grade of scintigraphic tumor uptake was not associated with treatment response (odds ratio [OR], 0.98; 95% CI, 0.26-3.14; P = 1.00).

CONCLUSIONS

Response to [(90)Y-DOTA]-TOC in metastasized iodine-refractory thyroid cancer was associated with longer survival. Upcoming trials should aim to increase the number of treatment cycles.

New perspectives on the treatment of differentiated thyroid cancer

Even though differentiated thyroid carcinoma is a slow growing and usually curable disease, recurrence occurs in 20-40% and cellular dedifferentiation in up to 5% of cases. Conventional chemotherapy and radiotherapy have just a modest effect on advanced thyroid cancer. Therefore, dedifferentiated thyroid cancer represents a therapeutic dilemma and a critical area of research. Targeted therapy, a new generation of anticancer treatment, is planned to interfere with a specific molecular target, typically a protein that is believed to have a critical role in tumor growth or progression. Since many of the tumor-initiation events have already been identified in thyroid carcinogenesis, targeted therapy is a promising therapeutic tool for advanced thyroid cancer. Several new drugs are currently being tested in in vitro and in vivo studies and some of them are already being used in clinical trials, like small molecule tyrosine kinase inhibitors. In this review, we discuss the bases of targeted therapies, the principal drugs already tested and also options of redifferentiation therapy for thyroid carcinoma.

Thyroid cancer molecular signaling pathways and use of targeted therapy

Several agents are currently being tested that target thyroid molecular signaling and cancer cell biology. The pathways involved include but are not limited to the Ras pathway, vascular endothelial growth factor and epidermal growth factor receptors and antibodies, angiogenesis inhibitors, tyrosine kinase inhibitors, heat shock protein inhibitors, demethylating agents, histone deacetylase inhibitors, and gene therapy. Each of these targeted approaches holds promise for our future ability to treat patients with thyroid cancer unresponsive to traditional therapy.

Nódulos de tireóide e câncer diferenciado de tireóide: consenso brasileiro

Os nódulos tireoidianos constituem a principal manifestação clínica de uma série de doenças da tireóide com uma prevalência de aproximadamente 10% na população adulta. O maior desafio é excluir o câncer da tireóide, que ocorre em 5 a 10% dos casos. Os carcinomas diferenciados respondem por 90% dos casos de todas as neoplasias malignas da tireóide. A maioria dos pacientes com carcinoma diferenciado apresenta, geralmente, um bom prognóstico quando tratada adequadamente, com índices de mortalidade similares à população geral. No entanto, alguns indivíduos apresentam doença agressiva, desafiando o conhecimento atual e ilustrando a complexidade do manejo dessa neoplasia. No presente trabalho, reunimos 8 membros do Departamento de Tireóide da Sociedade Brasileira de Endocrinologia & Metabologia, para elaborarmos, por consenso, as diretrizes brasileiras no manejo dos nódulos tireoidianos e do câncer diferenciado da tireóide. Os membros participantes representam diferentes Centros Universitários do Brasil, refletindo diferentes abordagens diagnósticas e terapêuticas. Inicialmente, cada participante ficou responsável pela redação de determinado tema a ser enviado ao Coordenador, que, após revisão editorial e elaboração da primeira versão do manuscrito, enviou ao grupo para sugestões e aperfeiçoamentos. Quando concluído, o manuscrito foi novamente enviado e revisado por todos. A elaboração dessas diretrizes foi baseada na experiência dos participantes e revisão pertinente da literatura.

Thyroid Tumors in Dogs and Cats

The clinical presentation and biologic behavior of thyroid tumors vary widely among dogs, cats, and human beings. Although thyroid tumors in dogs are rare, they are most likely to be malignant. Clinical signs are usually the result of impingement on surrounding structures, and clinical hyperthyroidism is rare. In contrast, hyperthyroidism resulting from benign thyroid proliferation is relatively common among older cats. Malignant tumors are extremely uncommon but have high metastatic potential. Irrespective of the tumor's ability to produce functional thyroid hormone, scintigraphy is often helpful in the diagnosis and staging of thyroid tumors in all three species. Treatment with surgery is a reasonable treatment option for noninvasive tumors. Iodine 131 is a well-established treatment for thyroid nodules in cats, but its effectiveness in dogs is controversial. In dogs, external beam radiation therapy has produced more consistent results in affording local tumor control when surgery is not possible.

New therapeutic approaches for metastatic thyroid carcinoma

Treatment of metastatic differentiated thyroid cancer (DTC) includes the use of radioiodine and suppressive thyroid hormone treatment. A third of patients with distant metastases (who have radioiodine uptake, are younger than 40 years, have small metastases, and have well differentiated thyroid tumour) can be cured with radioiodine treatment. For other patients, there are no effective treatment modalities. However, the recent availability of molecularly targeted treatments has led to changes in the treatment strategy for DTC in patients with distant metastases, especially in those who are resistant to radioiodine treatment.

Cyclooxygenase-2: a novel target in human solid tumors

The enzyme cyclooxygenase-2, which is involved in the conversion of arachidonic acid-to-prostanoid synthesis, plays a key role in many inflammatory and proliferative reactions. Experimental data have shown that prostaglandins have a central action in therapeutic targeting not only in the treatment of many inflammatory diseases but also in several types of human cancers. Inhibitors of cyclooxygenase activity seem to protect against carcinoma development and show promise as chemopreventive agents and possible target therapies. Data support new treatments for patients with solid cancers tailored to the molecular characteristics of the individual tumor.