Vascular endothelial growth factor monoclonal antibody inhibits growth of anaplastic thyroid cancer xenografts in nude mice

Pulmonary cavitation in patients with thyroid cancer receiving antiangiogenic agents

Background

Thyroid malignancies are among the most common endocrine cancers worldwide. Owing to the angiogenic nature of these malignancies, tyrosine kinase inhibitors (TKIs) are an attractive potential treatment. However, TKIs have been associated with an increased risk of tumor cavitation, in turn linked to poor outcomes, in patients with malignancies in the lungs, where thyroid cancer commonly metastasizes.

Method

We performe d a retrospective cohort study of patients with thyroid cancer and evidence of metastatic disease to the lung that were treated with multi-targeted antiangiogenic TKIs. The primary objective of this study was to determine the incidence of pulmonary cavitation. The secondary objective was to evaluate the effect of pulmonary cavitation on survival.

Results

Of the 83 patients with pulmonary nodules, 10 developed cavitation during treatment. Of these 83 patients, two patients had to stop the treatment due to pneumothorax. Additionally, cavitation did not demonstrate any significant effect on survival.

Conclusion

In patients with thyroid cancer and evidence of metastatic disease to the chest, the use of multi-targeted TKIs led to cavitations that were not uncommon but clinical consequences were marginal. Treatment was stopped only in two patients that developed pneumothorax, however the small sample is a strong limitation of our study.

A sequential targeting nanoplatform for anaplastic thyroid carcinoma theranostics

Effective accumulation of nanoparticles (NPs) in tumor regions is one of the major motivations in nanotechnology research and that the establishment of an efficient targeting nanoplatform for the treatment of malignant tumors is urgently needed for theranostic applications. In this study, we engineered multifunctional sequential targeting NPs for achieving synergistic antiangiogenic photothermal therapy (PTT) and multimodal imaging-guided diagnosis for anaplastic thyroid carcinoma (ATC) theranostics. Antibody bevacizumab with an affinity towards vascular endothelial growth factor (VEGF) on the tumor cell surface was conjugated onto the surface of polymer NPs for VEGF targeting and antiangiogenic therapy. Encapsulated IR825 was employed as a photothermal agent (PTA) with a mitochondrial targeting capability, which further cascades NPs into mitochondria to enhance hyperthermic efficiency in the ablation of tumor cells. Importantly, the combination of bevacizumab and IR825 in a single nanosystem achieved desirable accumulations of NPs and that sequential targeted PTT combined with antiangiogenesis significantly promoted the therapeutic efficiency in eradicating tumors by near-infrared (NIR) laser irradiation. Furthermore, these NPs are extraordinary contrast agents for photoacoustic, ultrasound and fluorescence imaging applications, providing multimodal imaging capabilities for therapeutic monitoring and a precise diagnosis. Therefore, this multifunctional nanoplatform provides a promising theranostic strategy for extremely malignant ATC. STATEMENT OF SIGNIFICANCE: Anaplastic thyroid carcinoma (ATC), with extremely aggressive behavior, lacks a satisfactory therapeutic method and a comprehensive early diagnostic strategy. Herein, we successfully synthesized a sequential targeting nanoplatform (IR825@Bev-PLGA-PFP NPs) with theranostic function, which specifically binds to VEGF on the tumor cell surface and further cascades into mitochondria to achieve effective accumulation of NPs in the tumor regions. As a result, it solves the urgent demand for ATC detection and therapy. By breaking the limitation of traditional target, such as low efficacy and frequent recurrence as the results of low accumulation, sequential targeting combined with synergistic antiangiogenic PTT completely eradicates tumors without any residual tissue and side effect. Therefore, this strategy paves a solid way for further investigation in the theranostic progressing of ATC.

Phase 2 study of vascular endothelial growth factor trap for the treatment of metastatic thyroid cancer

BACKGROUND

Several multitargeted tyrosine kinase inhibitors (TKIs) have demonstrated activity in patients with thyroid cancer that is refractory to radioactive iodine (RAI). The antitumor effect is attributed at least in part to the ability of these TKIs to inhibit angiogenesis in these vascular tumors. Vascular endothelial growth factor (VEGF) Trap (VT) is a recombinantly produced fusion protein consisting solely of human sequences for VEGF receptors 1 and 2 extracellular domains and human immunoglobulin 1. Evaluating VT in patients with thyroid cancer is reasonable considering the activity observed with TKIs targeting VEGF.

METHODS

The current study was a single-institution, phase 2, Simon 2-stage design (21 to >41 patients) study based on the objective response rate and/or 6-month progression-free survival as the primary endpoints. Eligible patients were required to have progressive, RAI-refractory and/or [¹⁸ F]fludeoxyglucose-avid, recurrent and/or metastatic, nonmedullary, nonanaplastic thyroid cancer; disease that was measurable using Response Evaluation Criteria In Solid Tumors (RECIST) criteria; and adequate organ and bone marrow function. VT at a dose of 4 mg/kg intravenously was administered every 14 days.

RESULTS

A total of 40 patients were included in the analysis. Of these patients, 24 had papillary thyroid cancer, 2 had follicular thyroid cancer, and 11 had Hurthle cell thyroid cancer. The final 3 tumors were classified as poorly differentiated. There were no complete and/or partial responses noted; 34 patients achieved stable disease and 6 patients experienced disease progression as their best response. Of the 34 patients with stable disease, 16 remained on the study for >6 months and 6 patients remained on the study for >12 months. The median duration on treatment was 4.1 months (range, 0.6-30.8 months).

CONCLUSIONS

Unlike TKIs, which have shown responses in this setting, to the authors' knowledge there have been no responses observed with the use of single-agent VT to date. It does not appear to be a promising drug for the treatment of patients with thyroid cancer.

Antitumor Effect of 131I-Labeled Anti-VEGFR2 Targeted Mesoporous Silica Nanoparticles in Anaplastic Thyroid Cancer

Anaplastic thyroid cancer (ATC) comprises approximately 2% of all thyroid cancers, and its median survival rate remains poor because of its resistance to conventional therapy. Vascular endothelial growth factor receptor (VEGFR)-targeted therapeutics-loaded mesoporous silica nanoparticles represent a major advance for angiogenesis imaging and inhibition in lethal cancers. In the present study, we aimed to assess whether ¹³¹I-labeled anti-VEGFR2 targeted mesoporous silica nanoparticles would have antitumor efficacy in an ATC tumor-bearing nude mouse model. Using in vitro and in vivo studies, we investigated the increased targeting ability and retention time in the anti-VEGFR2 targeted group using confocal microscopy and a γ counter. The tumor tissue radioactivity of the anti-VEGFR2 targeted group at 24 and 72 h after intratumoral injection was significantly higher than that of the non-targeted groups (all P < 0.05). Moreover, we found that radioactive accumulation was obvious even at 3 week post-injection in the anti-VEGFR2 targeted group via single-photon emission computed tomography/computed tomography, which was not seen at 3 day post-injection in the Na¹³¹I group. Meanwhile, compared with the non-targeted group, tumor growth in the targeted group was significantly inhibited, without causing apparent systemic toxic effects. Additionally, the median survival time in the targeted group (41 days) was significantly prolonged compared with that in the non-targeted (34 days) or Na¹³¹I (25 days) groups (both P < 0.01). Our data support the view that the as-developed ¹³¹I-labeled anti-VEGFR2 targeted mesoporous silica nanoparticles showed promising results in ATC tumor-bearing mouse model and such an approach might represent a novel therapeutic option for ATC.

Antineoplastic Effect of Lenvatinib and Vandetanib in Primary Anaplastic Thyroid Cancer Cells Obtained From Biopsy or Fine Needle Aspiration

Anaplastic thyroid carcinoma (ATC) is a malignant tumor of the thyroid gland, infrequent but with a very poor prognosis, as it rapidly causes death (mean survival of about 6 months). ATC treatment includes a multimodal protocol consisting of surgery, chemotherapy (doxorubicin and cisplatin), and hyperfractionated accelerated external beam radiotherapy (median patient survival of 10 months). For this reason, the identification of an effective systemic treatment for ATC would be a major advance in the management of this deadly thyroid cancer. The opportunity to test the sensitivity to different drugs of primary cells from ATC (pATC) cultures, obtained from each patients, could improve the effectiveness of the treatment. Then, the administration of inactive therapeutics could be avoided. Our aim is to investigate the antineoplastic effect of two tyrosine kinase inhibitors (TKIs; lenvatinib, vandetanib) in pATC obtained both from biopsy (biop-pATC), and from fine needle aspiration (FNA-pATC). The antiproliferative activity of lenvatinib and vandetanib was evaluated in 6 ATC patients, on biop-pATC, such as on FNA-pATC. A significant reduction of proliferation (obtained by WST-1 assay) vs. control was shown with lenvatinib and vandetanib in FNA-pATC, as well as in biop-pATC. The percentage of apoptosis in FNA-pATC, or biop-pATC, increased with both compounds dose-dependently. pATC cells from FNA, or biopsy, had a similar sensitivity to lenvatinib and vandetanib. In conclusion, primary cells (biop-pATC or FNA-pATC) have a similar sensitivity to TKIs, and lenvatinib and vandetanib are effective in reducing cell growth, increasing apoptosis in ATC. The possibility to test the sensitivity to different TKIs in each patient could open the way to personalized treatments, avoiding the administration of ineffective, and potentially dangerous, drugs.

Differentiated thyroid cancer with liver metastases: lessons learned from managing a series of 14 patients

Liver metastases from differentiated thyroid carcinoma (LMDTC) are rare and usually occur in disseminated metastatic disease. The aim of this study was to review the diagnosis and management of LMDTC. Between 1995 and 2011, 14 patients with a mean age of 59.7 years (+/-10.2) were treated for LMDTC. Data were retrospectively reviewed and analyzed. Seven patients had distant metastases at diagnosis, including 2 with synchronous liver lesions. The average time of onset of LMDTC from initial diagnosis was 52.2 months (+/49.5). All LMDTC were discovered during routine radiologic monitoring. Histologic analysis confirmed LMDTC in 5 patients. Eight patients received tyrosine kinase inhibitors, 1 patient underwent resection of their LMDTC after chemotherapy. Six patients (disseminated metastases, significant comorbidities) did not receive any specific treatment. The median survival after diagnosis of LMDTC was 17.4 months (+/-3.3): 23.6 months (+/-2.9) for patients who underwent chemotherapy versus 3.9 months (+/-0.9) for patients who did not receive any specific treatment (P < 0.001). Developing DTC liver metastasis is a very poor prognostic sign. Chemotherapy by TKIs, especially, hold promise in the cure of LMDTC for selected patients.

CLM29 and CLM24, pyrazolopyrimidine derivatives, have antitumoral activity in vitro in anaplastic thyroid cancer, with or without BRAF mutation

We have studied the antitumor activity of two new "pyrazolo[3,4-d]pyrimidine" compounds (CLM29 and CLM24) that inhibit several targets (including the RET tyrosine kinase, epidermal growth factor receptor, vascular endothelial growth factor receptor, with an antiangiogenic effect) in primary anaplastic thyroid cancer (ATC) cell cultures and in the human cell line 8305C (undifferentiated thyroid cancer). The antitumor effect of CLM29 and CLM24 was tested in: nine primary ATC cultures obtained from patients at the time of surgery at the concentrations of 1, 5, 10, 30, 50 µM; in 8305C cells at 1, 5, 10, 30, 50 µM for CLM29, and 0.001, 0.01, 0.1, 1, 10, 100 µM for CLM24. CLM29, and CLM24 significantly inhibited the proliferation of 8305C cells. A significant reduction of proliferation with CLM29 and CLM24 in ATC cells (P < 0.01, for both, ANOVA) was shown. CLM29 and CLM24 increased the percentage of apoptotic ATC cells dose-dependently (P < 0.001, ANOVA). The (V600E) BRAF mutation was observed in three ATCs; the results about the inhibition of proliferation by CLM29 and CLM24, obtained in ATC from tumors with (V600E) BRAF mutation were similar to those from tumors without BRAF mutation. CLM29 inhibited migration and invasion (P < 0.01) of primary ATC cells, while CLM24 had no significant effect. The antitumor activity of two new "pyrazolo[3,4-d]pyrimidine" compounds (CLM24, CLM29) in vitro in ATC, independent from BRAF mutation, has been shown, allowing a future clinical evaluation.

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.

Complete response to weekly carboplatin-docetaxel chemotherapy in a 91-year-old woman with anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is an unusual tumor with the worst prognosis among thyroid malignancies. Treatment of the patients diagnosed with ATC is not standardized and the feasible options include surgery, radiotherapy and chemotherapy. ATC cannot be regarded as a very chemo-sensitive tumor. Herein, we reported a case of a 91-year-old woman with complete response after induction chemotherapy (weekly carboplatin and docetaxel) that underwent subsequent radiotherapy.

Cisplatin based chemotherapy in patients with advanced differentiated thyroid carcinoma refractory to I131 treatment

Purpose:

The purpose of the study was to evaluate the activity and toxicity of cisplatin based chemotherapy in patients with advanced differentiated thyroid cancer refractory to radioactive iodine (I131).

Patients and Methods:

We retrospectively reviewed the records of 20 patients with advanced thyroid cancer treated with cyclophosphamide 500 mg/m² on day 1, doxorubicin 50 mg/m² day 1 and cisplatin 50 mg/m² day 1 of a 21 days cycle community-acquired pneumonia (CAP) or the same regimens without cyclophosphamide adriamycin and Platinum (AP).

Results:

Median age of patients was 65 years (range 54-80). The majority of patients had lung metastases (60%). 4 (20%) patients achieved a partial response. Stable disease was achieved in 6 (30%) patients. Overall clinical response was 50%. Mean follow-up time was 8 months (range 4-17). Mean progression free survival was 6 months (range 3-12). Mean overall survival was 9 months (range 4-17). Patients with partial remission had a mean time to disease progression of 9 months. 4 (20%) patients had Grade 3 or 4 neutropenia. One patient had febrile neutropenia. Mild neuropathy was recorded in 5 (25%) of patients. There were no treatment related deaths.

Conclusion:

The combination of CAP is active in the treatment of advanced thyroid cancer with tolerable toxicity. This regimen may still be used in patients who could not be treated with targeted therapy or combined with antiangiogenic drugs in future studies.

Diagnostic and prognostic markers in differentiated thyroid cancer

The MAPK/ERK (mitogen-activated protein kinase/extracellular signal- regulated kinase signaling pathway) and PI3K/Akt (lipid kinase phoshoinositide-3-kinase signaling pathway) play an important role in transmission of cell signals through transduction systems as ligands, transmembrane receptors and cytoplasmic secondary messengers to cell nucleus, where they influence the expression of genes that regulate important cellular processes: cell growth, proliferation and apoptosis. The genes, coding the signaling cascade proteins (RET, RAS, BRAF, PI3K, PTEN, AKT), are mutated or aberrantly expressed in thyroid cancer derived from follicular thyroid cell. Genetic and epigenetic alternations, concerning MAPK/ERK and PI3K/Akt signaling pathways, contribute to their activation and interaction in consequence of malignant follicular cell transformation. Moreover, it is additionally pointed out that genetic, as well as epigenetic DNA changing via aberrant methylation of several tumor suppressor and thyroid-specific genes is associated with tumor aggressiveness, being a jointly responsible mechanism for thyroid tumorigenesis. In the present manuscript the currently developed diagnostic and prognostic genetic/epigenetic markers are presented; the understanding of this molecular mechanism provides access to novel molecular therapeutic strategies.

Anaplastic thyroid carcinoma

Thyroid cancers represent about 1% of all human cancers. Differentiate thyroid carcinomas (DTCs), papillary and follicular cancers, are the most frequent forms, instead Anaplastic Thyroid Carcinoma (ATC) is estimated to comprise 1-2% of thyroid malignancies and it accounts for 14-39% of thyroid cancer deaths. The annual incidence of ATC is about one to two cases/million, with the overall incidence being higher in Europe (and area of endemic goiter) than in USA. ATC has a more complex genotype than DTCs, with chromosomal aberrations present in 85-100% of cases. A small number of gene mutations have been identified, and there appears to be a progression in mutations acquired during dedifferentiation. The mean survival time is around 6 months from diagnosis an outcome that is frequently not altered by treatment. ATC presents with a rapidly growing fixed and hard neck mass, often metastatic local lymph nodes appreciable on examination and/or vocal paralysis. Symptoms may reflect rapid growth of tumor with local invasion and/or compression. The majority of patients with ATC die from aggressive local regional disease, primarily from upper airway respiratory failure. For this reason, aggressive local therapy is indicated in all patients who can tolerate it. Although rarely possible, complete surgical resection gives the best chance of long-term control and improved survival. Therapy options include surgery, external beam radiation therapy, tracheostomy, chemotherapy, and investigational clinical trials. Multimodal or combination therapy should be useful. In fact, surgical debulking of local tumor, combined with external beam radiation therapy and chemotherapy as neoadjuvant (before surgery) or adjuvant (after surgery) therapy, may prevent death from local airway obstruction and as best may slight prolong survival. Investigational clinical trials in phase I or in phase II are actually in running and they include anti-angiogenetic drugs, multi-kinase inhibitor drugs.

Thyroid cancer: pathogenesis and targeted therapy

Therapeutic options for advanced, unresectable radioiodine-resistant thyroid cancers have historically been limited. Recent progress in understanding the pathogenesis of the various subtypes of thyroid cancer has led to increased interest in the development of targeted therapies, with potential strategies including angiogenesis inhibition, inhibition of aberrant intracellular signaling in the MAPK and PI3K/AKT/mTOR pathways, radioimmunotherapy, and redifferentiation agents. On the basis of a recent positive phase III clinical trial, the RET, vascular endothelial growth factor receptor (VEGFR), and epidermal growth factor receptor (EGFR) inhibitor vandetanib has received FDA approval as of April 2011 for use in the treatment of advanced medullary thyroid cancer. Several other recent phase II clinical trials in advanced thyroid cancer have demonstrated significant activity, and multiple other promising therapeutic strategies are in earlier phases of clinical development. The recent progress in targeted therapy is already revolutionizing management paradigms for advanced thyroid cancer, and will likely continue to dramatically expand treatment options in the coming years.

Anaplastic thyroid carcinoma: A comprehensive review of current and future therapeutic options

Anaplastic thyroid carcinoma (ATC) is the rarest, but deadliest histologic type among thyroid malignancies, with a dismal median survival of 3-9 mo. Even though ATC accounts for less than 2% of all thyroid tumors, it is responsible for 14%-39% of thyroid carcinoma-related deaths. ATC clinically presents as a rapidly growing mass in the neck, associated with dyspnoea, dysphagia and vocal cord paralysis. It is usually locally advanced and often metastatic at initial presentation. For operable diseases, the combination of radical surgery with adjuvant radiotherapy or chemotherapy, using agents such as doxorubicin and cisplatin, is the best treatment strategy. Cytotoxic drugs for advanced/metastatic ATC are poorly effective. On the other hand, targeted agents might represent a viable therapeutic option. Axitinib, combretastatin A4, sorafenib and imatinib have been tested in small clinical trials of ATC, with a promising disease control rate ranging from 33% to 75%. Other clinical trials of targeted therapy for thyroid carcinoma are currently ongoing. Biological agents that are under investigation include pazopanib, gefitinib and everolimus. With the very limited therapeutic armamentarium available at the present time, targeted therapy constitutes an exciting new horizon for ATC. In future, biological agents will probably represent the standard of care for this aggressive malignancy, in the same fashion as it has recently occurred for other chemo-refractory tumors, such as kidney and hepatic cancer.

Response to sorafenib at a low dose in patients with radioiodine-refractory pulmonary metastases from papillary thyroid carcinoma

BACKGROUND

Sorafenib has shown promise in the treatment of patients with advanced or metastatic thyroid carcinoma. However, the optimal dose has not been established and data on Chinese population are not available. We conducted a study to assess the responses to sorafenib at a low dose of 200 mg twice daily in patients with progressive radioiodine-refractory pulmonary metastases from papillary thyroid carcinoma (PTC).

PATIENTS AND METHODS

Eligible patients received sorafenib 200 mg orally twice daily. Responses were assessed using Response Evaluation Criteria in Solid Tumors and adverse events were assessed periodically. The end points included response rate and progression-free survival.

RESULTS

Nine patients with radioiodine-refractory PTC were enrolled in the study and treated for a minimum of 13 weeks. The objective partial response rate was 33%. The stable disease rate was 44%. The mean progression-free survival was 42 weeks (95% confidence interval, 29.5 to 53.9). Two patients showed disease progression, and one of them died at 4 months after beginning of treatment. There was a marked and rapid change in the serum thyroglobulin level after start of treatment, with a mean decrease of 60% within 12 weeks, consistent with radiographic findings. Although the types of toxicities were consistent with other sorafenib trials, their severity was relatively mild. None of the patients discontinued sorafenib or reduced their dose because of treatment-related adverse events.

CONCLUSION

Sorafenib at a dose of 200 mg twice daily has a potential therapeutic effect and is well tolerated in Chinese patients with PTC and radioiodine-refractory pulmonary metastases. Further study is warranted with a larger cohort of patients.

The evolving field of tyrosine kinase inhibitors in the treatment of endocrine tumors

Activation of tyrosine kinase receptors (TKRs) and their related pathways has been associated with development of endocrine tumors. Compounds that target and inactivate the kinase function of these receptors, tyrosine kinase inhibitors (TKIs), are now being applied to the treatment of endocrine tumors. Recent clinical trials of TKIs in patients with advanced thyroid cancer, islet cell carcinoma, and carcinoid have shown promising preliminary results. Significant reductions in tumor size have been described in medullary and papillary thyroid carcinoma, although no complete responses have been reported. Case reports have described significant tumor volume reductions of malignant pheochromocytomas and paragangliomas. In addition, these compounds showed an initial tumoricidal or apoptotic response followed by long-term static effects on tumor growth. Despite the promising preliminary results, this class of therapeutic agents has a broad spectrum of adverse effects, mediated by inhibition of kinase activities in normal tissues. These adverse effects will have to be balanced with their benefit in clinical use. New strategies will have to be applied in clinical research to achieve optimal benefits. In this review, we will address the genetic alterations of TKRs, the rationale for utilizing TKIs for endocrine tumors, and current information on tumor and patient responses to specific TKIs. We will also discuss the adverse effects related to TKI treatment and the mechanisms involved. Finally, we will summarize the challenges associated with use of this class of compounds and potential solutions.

Targeted therapies in thyroid cancer

Differentiated thyroid carcinoma is the most frequent neoplasm of the endocrine system. Although thyroid cancer usually has an excellent prognosis, no therapeutic options are available for patients that develop metastases and are or became resistant to radioiodine therapy. The deeper knowledge of molecular aberrations that characterize tumor growth has provided novel targets in cancer therapy. Several proteins have been implicated as having a crucial role in the carcinogenesis of differentiated thyroid cancer, such as those involved in RET/PTC-RAS-RAF-MAPK pathway. Moreover, vascular aberrations and angiogenesis equilibrium have also been related to tumor growth. The development of new, targeted therapies and their encouraging initial results have opened a hopeful opportunity of treatment for these orphan therapy tumor patients.

[Angiogenesis and thyroid cancer]

During the last two decades, the understanding of molecular biology of thyroid cancers has greatly improved, and this has permitted the development of novel therapeutic tools in patients with refractory disease. Kinase inhibitors inhibit kinases of the vascular endothelial growth factor (VEGF) receptors, and by doing this inhibit angiogenesis, and some of these agents also inhibit other kinases of the MAPkinase pathway. These inhibitors are effective in differentiated and medullary thyroid cancers, and induce a partial response or a long term stabilisation in more than half of patients.

Phase II trial of sorafenib in advanced thyroid cancer

PURPOSE

Given the molecular pathophysiology of thyroid cancer and the spectrum of kinases inhibited by sorafenib, including Raf kinase, vascular endothelial growth factor receptors, platelet-derived growth factor receptor, and RET tyrosine kinases, we conducted an open-label phase II trial to determine the efficacy of sorafenib in patients with advanced thyroid carcinoma.

PATIENTS AND METHODS

Eligible patients with metastatic, iodine-refractory thyroid carcinoma received sorafenib 400 mg orally twice daily. Responses were measured radiographically every 2 to 3 months. The study end points included response rate, progression-free survival (PFS), and best response by Response Evaluation Criteria in Solid Tumors.

RESULTS

Thirty patients were entered onto the study and treated for a minimum of 16 weeks. Seven patients (23%; 95% CI, 0.10 to 0.42) had a partial response lasting 18+ to 84 weeks. Sixteen patients (53%; 95% CI, 0.34 to 0.72) had stable disease lasting 14 to 89+ weeks. Seventeen (95%) of 19 patients for whom serial thyroglobulin levels were available showed a marked and rapid response in thyroglobulin levels with a mean decrease of 70%. The median PFS was 79 weeks. Toxicity was consistent with other sorafenib trials, although a single patient died of liver failure that was likely treatment related.

CONCLUSION

Sorafenib has clinically relevant antitumor activity in patients with metastatic, iodine-refractory thyroid carcinoma, with an overall clinical benefit rate (partial response + stable disease) of 77%, median PFS of 79 weeks, and an overall acceptable safety profile. These results represent a significant advance over chemotherapy in both response rate and PFS and support further investigation of this agent in these patients.

[Gustave Roussy's (1874-1948) contribution to neuroendocrinology]

Gustave Roussy (1874-1948) is remembered as a distinguished French neuropathologist and a leader in the field of oncology. However, his original contribution to the study of hypothalamic functions and neuroendocrinology remains ignored. Among Roussy's discoveries is the first experimental demonstration of the hypothalamic origin of diabetes insipidus and adiposo-genital dystrophy. Also, based on his own histological work, he pioneered the concept of neurosecretion, which was termed by him "neuricrinie".

VEGF in physiological process and thyroid disease

Angiogenesis is a physiological process involving the growth of new vessels from pre-existing vasculature. Vascular endothelial growth factor (VEGF) is an important regulator of both benign and malignant disease processes in the thyroid gland. The VEGF family includes seven members respectively named VEGF-A, also known as VPF (vascular permeability factor), VEGF-B, VEGF-C, VEGF-D, all described in mammals, VEGF-E (found in Parapoxviridae), VEGF-F (also called svVEGF, for snake venom VEGF, found in viper venom) and PlGF (placental growth factor). Thyrocytes are able to synthesize and secrete VEGF. VEGF-A is implicated in tumour growth and metastasis via blood vessels while VEGF-C and VEGF-D, involved in lymphangiogenesis, favour metastasis to the cervical lymph nodes in papillary thyroid carcinomas. High levels of VEGF expression in thyroid tumour cells may correlate with a poorer outcome in papillary thyroid carcinomas. Because of its important role in malignant angiogenesis, VEGF is the preferential target of a new variety of therapeutic agents called angiogenesis inhibitors.

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.

Phase II trial of thalidomide for therapy of radioiodine-unresponsive and rapidly progressive thyroid carcinomas

BACKGROUND

There are no known effective therapies for distantly metastatic, rapidly progressive thyroid carcinomas unresponsive to radioiodine.

OBJECTIVE

Since thyroid carcinomas are hypervascular and thalidomide is antiangiogenic, we assessed thalidomide's tumoristatic effects and toxicity in a phase II trial.

DESIGN

Thirty-six patients with follicular, papillary, insular, or medullary thyroid carcinomas and distant, radioiodine-unresponsive metastases (volumes increasing >or= 30% per year before entry) were accrued between July 2001 and December 2002. Daily thalidomide started at 200 mg, increasing over 6 weeks to 800 mg or maximum tolerated dose. Toxicities and responses were assessed at 8-week intervals with tumor volume assessments.

MAIN OUTCOMES

Twenty-eight of 36 patients were evaluable, 5 with partial responses (PR: 18%; 95% confidence interval [95% CI]: 6-37%) and 9 patients with stable disease (SD: 32%; 95% CI: 12-42%) for overall 50% response (95% CI: 31-69%). Median PR duration was 4 months (range: 2-6 months), and SD duration was 6 months (range: 2-14 months). Median survival was 23.5 months for responders (PR + SD) and 11 months for nonresponders. Most frequent toxicity was fatigue (69% grade 1-2, 8% grade 3-4). Four patients had grade 3-4 infections (without neutropenia), one had pericardial effusion, and one had pulmonary embolus.

CONCLUSIONS

Thalidomide confers therapeutic benefit in subsets of thyroid cancer patients with rapidly progressive, distantly metastatic disease.

Tumor cytotoxicity and endothelial Rac inhibition induced by TNP-470 in anaplastic thyroid cancer

Anaplastic thyroid carcinoma is an aggressive form of cancer with no treatment. Angiogenesis inhibitors, such as TNP-470, a synthetic derivative of fumagillin, have been shown to reduce tumor size and increase survival in heterotopic animal models of thyroid cancer. Our goals were to determine the effect of TNP-470 on anaplastic thyroid cancer using an orthotopic murine model, to identify the molecular pathways of TNP-470 actions on endothelial cells, and to determine the non-endothelial tumor effects of TNP-470. We injected human anaplastic thyroid carcinoma cells (DRO'90) into the thyroid glands of nude mice. Mice received TNP-470 (30 mg/kg) s.c. for 6 weeks. TNP-470 prolonged survival and reduced liver metastases. TNP-470 had direct cytotoxic effects on anaplastic thyroid carcinoma cells in vitro and in vivo. Paradoxically, TNP-470 increased vascular endothelial growth factor secretion from tumor cells in vitro and in vivo. However, there was no associated increase in tumor microvessel density. In endothelial cells, TNP-470 prevented vascular endothelial growth factor-induced endothelial permeability, intercellular gap formation, and ruffle formation by preventing Rac1 activation.

Concurrent Cetuximab and Bevacizumab Therapy in a Murine Orthotopic Model of Anaplastic Thyroid Carcinoma

OBJECTIVE

To evaluate the therapeutic efficacy of bevacizumab and cetuximab, alone and in combination, in an orthotopic model of anaplastic thyroid carcinoma (ATC) in athymic nude mice.

STUDY DESIGN AND SETTING

This was a randomized, controlled in vivo study.

MATERIALS AND METHODS

The ATC cell line, ARO, was used to establish orthotopic xenografts of ATC in athymic nude mice. Mice were randomized to therapy for 4 weeks in one of four treatment groups: placebo, cetuximab, bevacizumab, or the combination of cetuximab and bevacizumab. A second study compared the antitumor efficacy of the cetuximab-bevacizumab combination with doxorubicin. In both studies, tumor volumes on completion were measured and compared. Immunohistochemical analysis was performed with antiCD31 and antiproliferating cell nuclear antigen (PCNA) antibodies to assess the in vivo mechanisms of action of these agents.

RESULTS

Cetuximab decreased the production of vascular endothelial growth factor by ATC cell lines in vitro. Mean tumor volumes for the control, bevacizumab, cetuximab, and combination groups at the end of the in vivo study were 291, 213, 94, and 42 mm(3), respectively. The differences in mean tumor volume for the control versus treatment groups were statistically significant. Immunohistochemical analysis showed decreased microvessel density and PCNA positivity in the treatment groups. In the doxorubicin comparison study, mean tumor volumes for control, doxorubicin, and combination antibody treatment groups were 175, 162, and 22 mm(3), respectively.

CONCLUSIONS

Cetuximab and bevacizumab alone and in combination inhibit tumor growth and angiogenesis in an in vivo model of ATC. Also, this therapy was superior to doxorubicin therapy.

Differential effects of cetuximab and AEE 788 on epidermal growth factor receptor (EGF-R) and vascular endothelial growth factor receptor (VEGF-R) in thyroid cancer cell lines

This study evaluated the role of EGF and the effects of EGF-targeting drugs (Cetuximab, AEE 788) on growth, apoptosis, and autocrine VEGF-secretion of thyroid cancer (TC) cells. Autocrine activation of the epidermal growth factor receptor (EGF-R) is commonly regarded to contribute to the malignant phenotype of TC cells and may therefore represent a rational therapeutic target. Out of a number of TC cell lines two anaplastic (Hth74, C643), one follicular (FTC133), and one papillary thyroid cancer cell line (TPC1) were analyzed in depth for VEGF-R-and EGF-R-expression, basal and EGF-stimulated (1-100 ng/ml) VEGF protein secretion and proliferation. Subsequently the antiprolifereative and antiangiogenic effect of cetuximab (Erbitux), a monoclonal antibody that blocks the EGF-R and AEE 788, a novel dual-kinase inhibitor of EGF-R and VEGF-R were assessed, and the downstream EGF-R signal transduction was analyzed by means of detecting phosphorylated pEGF-R, pVEGF-R, pAkt, and p-MAPK. EGF stimulated VEGF-mRNA expression and protein secretion in all TC cell lines. The EGF-R antagonist Cetuximab consistently decreased VEGF secretion in all TC cell lines (min. 15%, n.s. in C643 cells and max. 90% in Hth74 cells, P < 0.05), but did not affect tumor cell proliferation in vitro. In contrast, the EGF-R- and VEGF-R-kinase inhibitor AEE 788 not only reduced VEGF secretion (min. 55%, P < 0.05 in C643 and max. 75%, P < 0.05, in FTC133), but also exhibited a dose-dependent inhibition of tumor cell proliferation (min. 75%, P < 0.05 in C643 and max. 95%, P < 0.05 in Hth74) and was a potent inductor of apoptosis in two of four TC cell lines. These effects were always accompanied by reduced levels of pEGF-R, pVEGF-R, pAkt, and pMAPK. Although inhibition of the EGF-receptor by Cetuximab potently disrupts autocrine secretion of VEGF, only the concurrent inhibition of the VEGF- and EGF receptor, e.g., by AEE 788 induces reduced proliferation and apoptosis in vitro. This suggests a particular rationale for the use of tyrosine kinase inhibitors with dual modes of action such as AEE 788 in thyroid cancer.

Genetic alterations in thyroid cancer: the role of mouse models

Thyroid carcinomas are the most common endocrine neoplasms in humans, with a globally increasing incidence. Thyroid follicular cells and neuroendocrine (parafollicular) C cells are each susceptible to neoplastic transformation, resulting in thyroid cancers of differing phenotypes with unique associated genetic mutations and clinical outcomes. Over the past 15 years, several sophisticated genetically engineered mouse models of thyroid cancer have been created to further our understanding of the genetic events leading to thyroid carcinogenesis in vivo. The most significant mouse models of papillary, follicular, anaplastic, and medullary thyroid carcinoma are highlighted, with particular emphasis on the relationship between the relevant oncogenes in these models and genetic events in the naturally occurring human disease. Limitations of each model are presented, and the need for additional models to better recapitulate certain aspects of the human disease is discussed.

Papillary thyroid carcinoma with lymph node metastases

Papillary thyroid cancer (PTC) is the most frequently occurring human thyroid cancer with good prognosis following appropriate treatment. Lymph node (LN) metastases are the main way through which PTC spread cancer cells. The mechanisms underlying PTC with local invasion, LN metastases and distant metastases are not well investigated. Tumor secrete cytokines, such as vascular endothelial growth factor (VEGF)-C and -D bind to VEGF receptors on lymphatic endothelial cells and induce proliferation (budding) from nearby lymphatic capillaries and growth of new lymphatic capillaries. About one-third of patients can be diagnosed at the time of surgical findings. Different image studies, such as ultrasonography with fine needle aspiration cytology, scintigraphic localization and positron emission tomography were reported to detect LN metastases. Important factors in predicting LN metastases are vascular invasion, male gender, absence of tumor capsule, and perithyroid involvement. Tumor recurrence in LN after primary treatment of PTC had an independent and highly significant negative effect on survival in patients over 45 year-old. Recombinant adeno-associated virus-mediated gene transfer of sVEGFR3-Fc is a feasible therapeutic scheme for blocking lymphogenous metastasis. In conclusion, aggressive surgical procedures performed by experienced surgeons or postoperative radioactive iodine therapy to minimize local recurrence of LN for PTC patients with high risk.

Retinoic acid inhibits angiogenesis and tumor growth of thyroid cancer cells

The anti-proliferative effect of retinoic acid (RA) has been documented for various tumors. Some 40% of patients with advanced and poorly differentiated thyroid cancer have been shown to respond to RA with increased uptake of radioiodine. It has been suggested that these effects may be caused by redifferentiation. Presently, little is known about the effects of RA on tumor angiogenesis, a prerequisite for growth and metastatic spread. The aim of the current study was to determine, whether tumor-induced angiogenesis of thyroid cancer is affected by RA. In vitro, the effect of 0.1/10 microM 13-cis RA on tumor cell number (MTT assay) and secretion of VEGF (ELISA) was analyzed in three thyroid cancer cell lines (FTC 236, C634 and XTC), as well as in endothelial cells (HUVEC) over several passages. In vivo, tumor growth, VEGF-expression and microvessel density (VSD) of RA treated thyroid cancer cells after xenotransplantation to nude mice was evaluated by morphometric analysis. In vitro, thyroid cancer cell lines responded to RA with reduced proliferation, ranging from 26 to 34% after 2 weeks of treatment and with up to 80% reduced secretion of VEGF. In vivo, tumor volumes of animals receiving RA were reduced by 33% (FTC 236), 27% (C643) and 6% (XTC), respectively. VSD of experimental tumors was diminished in the FTC 236 (25%) and the C643 cell line (15%), and almost unchanged in XTC tumors (7%). In vivo, VEGF-expression and apoptosis were not significantly affected by RA. In vitro, proliferation of HUVEC was inhibited by conditioned medium of C643 cells pretreated with RA (0.1/10 microM), as well as by administration of RA (0.1/10 microM). This study confirms thyroid tumor cell growth to be inhibited by RA. It demonstrates a decrease of in vitro VEGF accumulation and reduction of VSD in experimental undifferentiated thyroid carcinoma, suggesting that reduced angiogenesis may be an important mechanism responsible for the therapeutic effect of RA in thyroid cancer. Moreover, a direct anti-proliferative effect of RA on human endothelial cells is suggested.

Anaplastic Thyroid Carcinoma: Expression Profile of Targets for Therapy Offers New Insights for Disease Treatment

BACKGROUND

Anaplastic thyroid cancer is an endocrine malignancy. Its rare and rapidly lethal disease course has made it challenging to study. Little is known regarding the expression by anaplastic tumors of molecular targets for new human anticancer agents that have been studied in the preclinical or clinical setting. The objective of this work was to evaluate the expression profile of anaplastic thyroid tumors for molecular targets for treatment.

METHODS

Of the 94 cases of anaplastic thyroid cancers diagnosed and treated in British Columbia, Canada over a 20-year period (1984-2004), 32 cases (34%) had adequate archival tissue available for evaluation. A tissue microarray was constructed from these anaplastic thyroid tumors and immunohistochemistry was utilized to evaluate expression of 31 molecular markers. The markers evaluated were: epidermal growth factor receptor (EGFR), HER2, HER3, HER4, ER, PR, uPA-R, clusterin, E-cadherin, beta-catenin, AMF-R, c-kit, VEGF, ILK, aurora A, aurora B, aurora C, RET, CA-IX, IGF1-R, p53, MDM2, p21, Bcl-2, cyclin D1, cyclin E, p27, calcitonin, MIB-1, TTF-1, and thyroglobulin.

RESULTS

A single tumor with strong calcitonin expression was identified as a poorly differentiated medullary carcinoma and excluded from the study cohort. The mean age of the anaplastic cohort was 66 years; 16 patients (51%) were females, and the median patient survival was 23 weeks. A wide range in molecular marker expression was observed by the anaplastic thyroid cancer tumors (0-100%). The therapeutic targets most frequently and most strongly overexpressed by the anaplastic tumors were: beta-catenin (41%), aurora A (41%), cyclin E (67%), cyclin D1 (77%), and EGFR (84%).

CONCLUSIONS

Anaplastic thyroid tumors exhibit considerable derangement of their cell cycle and multiple signal transduction pathways that leads to uncontrolled cellular proliferation and the development of genomic instability. This report is the first to comprehensively evaluate a panel of molecular targets for therapy of anaplastic thyroid cancer and supports the development of clinical trials with agents such as cetuximab, small-molecule tyrosine kinase inhibitors, and aurora kinase inhibitors, which may offer new hope for individuals diagnosed with this fatal thyroid malignancy.

Targeting the EGF/VEGF-R system by tyrosine-kinase inhibitors--a novel antiproliferative/antiangiogenic strategy in thyroid cancer

AIM

In thyroid cancer (TC), endothelial growth factor (EGF) has been associated with dedifferentiation, tumor cell proliferation, and angiogenesis. Vascular endothelial growth factor (VEGF) has been documented to be the main stimulator of angiogenesis in the thyroid gland. Patients with undifferentiated thyroid cancer are in desperate need of new therapeutic strategies because common protocols of therapy usually fail. The aim of this study, therefore, was to evaluate two tyrosine-kinase inhibitors (TKI, ZD 1839 gefitinib and ZD 6474 vandetanib), directed against the EGF/VEGF receptor for possible antitumor therapy in thyroid cancer.

METHODS

EGF/VEGF-R was documented in anaplastic (Hth74, C643), follicular (FTC133), and papillary (TPC1) thyroid cancer cell lines by Western blot analysis. The antiproliferative effect of two TKI (0.1-10 microM) on thyroid cancer cell lines in vitro was quantified by MTT assay, the antiangiogenic effect by assessing secretion of VEGF by enzyme-linked immunosorbent assay (R&D Systems). ZD 1839 is mainly directed against EGF-R and ZD 6474 against VEGF-R (AstraZeneca, UK), single applications and combinations of compounds were evaluated.

RESULTS

EGF-R and VEGF-R as well as the phosphorylated receptor were documented in all of the cell lines. Administration of ZD1839 led to an up to 90% reduction of cell number in Hth74, 80% in C643, 50% in FTC133, and 90% in TPC1 (p < 0.05). ZD1839 induced a decrease of VEGF secretion between 30% in C643 and 90% in Hth74. Administration of ZD6474 led to an up to 95% reduction of cell number in Hth74, 85% in C643, 90% in FTC133, and 90% in TPC1 (p < 0.05). The ZD6474 induced decrease of VEGF secretion ranged between 20% (FTC133) and 60% (TPC1). Combinations of IC50 concentrations of TKI showed synergistic effects, resulting in additional inhibition of proliferation between 50 and 90% compared to single drug administration.

CONCLUSION

The EGF/EGF-R system resembles a powerful VEGF-stimulating pathway in all histiotypes of TC and can be inhibited by TKI. TKI directed against EGF-R as well as VEGF-R inhibit tumor cell proliferation and VEGF secretion in vitro. Combinations of TKI are more effective than strategies using single agents. It is suggested that targeting EGF-R/VEGF-R-mediated pathways may have therapeutic potential in some undifferentiated thyroid cancers.

Anaplastic Thyroid Carcinoma, Thyroid Lymphoma, and Metastasis to Thyroid

Anaplastic thyroid carcinoma, thyroid lymphoma, and secondary metastasis to the thyroid gland are uncommon thyroid malignancies. They represent significant challenges for the surgeon owing to difficulties in diagnosis, aggressive biology, and the infrequency of their presentation. An awareness and appreciation of multimodality treatment strategies is essential for their management.

Antisense p53 decreases production of VEGF in follicular thyroid cancer cells

Inactivating mutations of wild-type p53 (WTp53) tumor suppressor gene are common in anaplastic thyroid cancer (ATC) and are associated with poor prognosis. Mutated p53 (MTp53) has been implicated with angiogenesis. Therefore, the potential of MTp53 knockout by oligodeoxyribonucleotide phosphorothioates (ODNs) to affect VEGF production of undifferentiated thyroid cancer cells with a recessive MTp53 mutation was evaluated. Transient transfection with 20 bp ODNs complementary to portions of exon 10 of p53 and a negative control ODN (HIV-RT) were carried out in FTC-133 cells. In vitro secretion of VEGF protein was quantified by EIA and correlated to cell numbers, which was evaluated by in vitro MTT assay. Transfection of undifferentiated thyroid cancer cells with ODN reduced VEGF secretion of FTC-133 cells following transfection by 34% as compared to the negative control (cells transfected with ODN-HIV; p = 0.03). These results suggest that transient MTp53 knockout with ODNs complementary to p53 nucleotide sequences impair secretion of VEGF in the undifferentiated thyroid cancer cell line FTC-133.

Novel high-affinity PPARgamma agonist alone and in combination with paclitaxel inhibits human anaplastic thyroid carcinoma tumor growth via p21WAF1/CIP1

Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists demonstrate antitumor activity likely through transactivating genes that regulate cell proliferation, apoptosis, and differentiation. The PAX8/PPARgamma fusion oncogene, which is common in human follicular thyroid carcinomas appears to act via dominant negative suppression of wild-type PPARgamma, suggesting that it may be a tumor suppressor gene in thyroid cells. We have identified a novel high-affinity PPARgamma agonist (RS5444) that is dependent upon PPARgamma for its biological activity. This is the first report of this molecule and its antitumor activity. In vitro, the IC50 for growth inhibition is approximately 0.8 nM while anaplastic thyroid carcinoma (ATC) tumor growth was inhibited three- to fourfold in nude mice. siRNA against PPARgamma and a pharmacological antagonist demonstrated that functional PPARgamma was required for growth inhibitory activity of RS5444. RS5444 upregulated the cell cycle kinase inhibitor, p21WAF1/CIP1. Silencing p21WAF1/CIP1 rendered cells insensitive to RS5444. RS5444 plus paclitaxel demonstrated additive antiproliferative activity in cell culture and minimal ATC tumor growth in vivo. RS5444 did not induce apoptosis but combined with paclitaxel, doubled the apoptotic index compared to that of paclitaxel. Our data indicate that functional PPARgamma is a molecular target for therapy in ATC. We demonstrated that RS5444, a thiazolidinedione (Tzd) derivative, alone or in combination with paclitaxel, may provide therapeutic benefit to patients diagnosed with ATC.

Vascular endothelial growth factor in thyroid cancers

Vascular endothelial growth factor (VEGF) is an essential peptide in new vessel growth in physiology (endometrial growth, embryonic development); pathological conditions (diabetic retinopathy, rheumatoid arthritis); as well as in tumor cell growth, particularly distant metastases. This study focused on VEGF structure, receptors, and angiogensis in tumors, especially their roles in thyroid cancer. The VEGF mRNA undergoes alternative splicing events that generate four homodimeric isoforms, including VEGF121, VEGF165, VEGF189, or VEGF206. Using VEGF purified from a culture medium conditioned by A-431 human epidermoid carcinoma cells, VEGF-binding site complexes of 230, 170, and 125 kDa were detected on human umbilical vein endothelial cells. The VEGF specifically induced the tyrosine phosphorylation of a 190-kDa polypeptide, which had similar mass to the largest binding site detected through affinity cross-linking. A transmembrane receptor belongs to the tyrosine kinase family, fms-like tyrosine kinase (FLT). These receptor tyrosine kinases encoded by the FLT gene family have distinct functions in regulating blood vessel growth and differentiation. Regulation of VEGF is a complex, multistep mechanism in various kinds of cells and tissues. Hypoxia-dependent and -independent mechanisms are illustrated in different cancer tissues. Hypoxic tumor cells may switch to a proangiogenic phenotype, which increases VEGF transcription. Clinical applications of VEGF in cancer have included diagnosis, prediction of prognosis, and treatment in different solid tumors, including thyroid tumors. Studies involving thyroid cancer cell lines, serum level determination, immunohistocytochemical staining, molecular biological studies, and gene therapy to the in vivo clinical trials, have shown that antiangiogensis therapy can provide another treatment modality for thyroid cancer. Future studies focused on recombinant human anti-VEGF research involving patients with advanced thyroid cancer, and investigation of the protection of high-risk patients by using novel antiangiogenic vaccines, are warranted.

Paneling human thyroid cancer cell lines for candidate proteins for targeted anti-angiogenic therapy

Tumor angiogenesis is believed to result from an imbalance of pro- and anti-angiogenic factors, some of which are candidates for targeted therapy. Such therapy has raised hopes for patients with undifferentiated thyroid carcinomas, who are facing a grave prognosis with a survival of only months. In this study, in vivo growth of xenografted human thyroid carcinomas unexpectedly responded quite differently to neutralizing anti-vascular endothelial growth factor (VEGF) antibody. In particular, lasting inhibition as well as accelerated growth occurred after treatment. Consequently, a panel of anti-angiogenic factors was addressed in a representative sample of thyroid carcinoma lines. VEGF, fibroblast growth factor (FGF-2), and endostatin were demonstrated by Western blotting and EIA, whereas PDGF-A, PDGF-B, and IL-6 were negative. Quantification of VEGF, FGF-2, and endostatin revealed a wide range of concentrations from 500 to 4,200 pg/ml VEGF, 5 to 60 pg/ml FGF-2, and 50 to 300 pg/ml endostatin, not related to a particular histologic thyroid carcinoma background. Angiostatin (kringles 1-3) was detected in all, but one of the cell lines. Finally, aaATIII was confirmed in FTC133 cells. These data highlight the complex regulation of angiogenesis in thyroid carcinoma cell lines and suggest that the array of angiogenic factors differs markedly between individual cell lines. For the first time, angiostatin, endostatin, and possibly also aaATIII are identified as novel candidate regulators of angiogenesis in thyroid carcinoma cells.

Growth inhibition of orthotopic anaplastic thyroid carcinoma xenografts in nude mice by PTK787/ZK222584 and CPT-11

BACKGROUND

A preclinical evaluation of CPT-1 (Camptosar, irinotecan) and PTK787/ZK222584, a vascular endothelial growth factor receptor (VEGFR-2) tyrosine kinase inhibitor, as therapeutic agents against anaplastic thyroid carcinoma (ATC) was performed in vitro and in an orthotopic model of ATC in nude mice.

METHODS

The cytotoxic and cytostatic effects of CPT-11 on ATC cell lines were evaluated. The antitumor effects of CPT-11 in combination with PTK787/ZK222584 on orthotopic ATC xenografts in nude mice were also studied.

RESULTS

CPT-11 demonstrated significant antiproliferative effects on ATC cell lines. In vivo, PTK787/ZK222584, CPT-11, and the two agents together produced 61%, 82%, and 89% decrease in tumor growth, respectively. The differences in tumor volume between CPT-11 and CPT-11 + PTK787/ZK222584 groups were not statistically significant. PTK787/ZK222584 inhibited the phosphorylation of VEGFR-2 on tumor endothelium and decrease the tumor microvessel density.

CONCLUSIONS

The camptothecin class of chemotherapeutic agents and antiangiogenic agents such as PTK787/ZK222584 warrant further study as novel therapeutic agents against ATC.

Targeted molecular therapy of anaplastic thyroid carcinoma with AEE788

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human malignancies with a mean survival of only 6 months. The poor prognosis of patients with ATC reflects the current lack of curative therapeutic options and the need for development of novel therapeutic strategies. In this study, we report the results of a preclinical study of AEE788, a dual inhibitor of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) tyrosine kinases, against ATC. AEE788 was able to inhibit the proliferation and induce apoptosis of ATC cell lines in vitro. Administration of AEE788, alone and in combination with paclitaxel, to athymic nude mice bearing s.c. ATC xenografts inhibited the growth of ATC xenografts by 44% and 69%, respectively, compared with the control group. Furthermore, tumors from mice treated with AEE788, alone and in combination with paclitaxel, showed increase in apoptosis of tumor cells by approximately 6- and 8-fold, respectively, compared with the control group. The microvessel density within the ATC xenografts was decreased by >80% in the mice treated with AEE788 alone and in combination with paclitaxel compared with the control group. Lastly, immunofluorescence microscopy showed the inhibition of EGFR autophosphorylation on the tumor cells as well as the inhibition of VEGFR-2 autophosphorylation on tumor endothelium. Considering the fact that curative options seldom exist for patients with ATC, concurrent inhibition of EGFR and VEGFR tyrosine kinases seems to be a valid and promising anticancer strategy for these patients.

[Poorly differentiated thyroid carcinomas: new therapeutic considerations]

For most differentiated thyroid carcinomas, as papillary and follicular carcinomas, following total thyroidectomy and 131I therapy for thyroid remnant ablation, treatment with thyroid hormones to suppress TSH levels will reduce the growth of any remaining thyroid cancer cells, and thyroid cell-specific radiation therapy will either cure or control the disease. Thyroid carcinomas are considered poorly differentiated when they start to lose such functions as iodine uptake and thyrotropin-dependence for growth and production of thyroid proteins like NIS, thyroglobulin and desiodases. One of the greatest challenges in the management of patients with follicular cell-derived thyroid cancer is the treatment of tumors that progressed despite surgery, (131)I and T4 suppression of TSH. With the better knowledge of the abnormal molecular signaling in thyroid cancer cells, actually known targeted cancer therapies, directed against molecules involved in neoplastic transformation, are being used. As the critical molecular requirements for tumor initiation, maintenance and progression are identified, combination therapies with targeted agents acting on each of them will improve the treatment of poorly differentiated thyroid carcinoma.

Aplidin reduces growth of anaplastic thyroid cancer xenografts and the expression of several angiogenic genes

BACKGROUND

Anaplastic thyroid cancer (ATC) is one of the most aggressive and highly lethal human cancers. Median survival after diagnosis is 4-6 months despite available radiotherapy and chemotherapy. Additional treatments are needed for ATC. Vascular endothelial growth factor (VEGF) is a potent angiogenic stimulus, which is expressed by ATC. Previously, anti-VEGF antibody was used to block VEGF-dependent angiogenesis in ATC xenografts. This treatment induced partial (56%) but not complete tumor regression. Aplidin (APLD) is a marine derived antitumor agent currently in phase II clinical studies. Multiple activities of this compound have been described which likely contribute to its antiproliferative effect. Notably, APLD has been shown to have antiangiogenic properties which include: inhibition of VEGF secretion, reduction in the synthesis of the VEGF receptor (FLT-1), and blockade of matrix metalloproteinase production by endothelial cells. We hypothesized that Aplidin, with its broad spectrum of action and antiangiogenic properties, would be a potentially effective drug against ATC.

METHODS

Thirty BALB/c nu/nu mice were injected with ATC cells (ARO-81, 1 x 10(6)) and allowed to implant for 3 weeks. Animals were randomized to receive daily intraperitoneal injections of vehicle, low dose (0.5 mg/kg/day), or high dose (1.0 mg/kg/day) APLD. After 3 days, the animals were killed and the tumors were removed, weighed, and divided for RNA and protein analyses.

RESULTS

APLD significantly reduced ATC xenograft growth (low dose, 20% reduction, P = 0.01; high dose, 40% reduction, P < 0.001). This was associated with increased levels of apoptosis related proteins polyadenosylribose polymerase 85 (PARP-85, 75% increase, P = 0.024) and caspase 8 (greater than fivefold increase, P = 0.03). APLD treatment was further associated with lost or reduced expression of several genes that support angiogenesis to include: VEGF, hypoxia inducible factor 1(HIF-1), transforming growth factor-beta (TGFbeta), TGFbeta receptor 2 (TGFbetaR2), melanoma growth stimulating factor 1 (GRO1), cadherin, and vasostatin.

CONCLUSIONS

This data supports the hypothesis that APLD may be an effective adjunctive therapy against ATC. The demonstrated molecular impact against angiogenic related genes specifically supports future strategies combining APLD with VEGF interacting agents.

Angiogenesis in benign and malignant thyroid disease

CONTEXT

Angiogenesis has been recognized as an important process contributing to the pathophysiology of many benign and malignant diseases. It is not surprising, therefore, that this complex process is proving to be an important regulator of both benign and malignant disease processes in the thyroid gland. This paper will review the general principles of angiogenesis and lymphangiogenesis, as well as the importance of the balance between angiogenic stimulators and inhibitors in the normal thyroid gland. We will also review how this balance is disturbed in benign and malignant thyroid conditions. Finally, we will address the role manipulation of this process may play in the development of novel treatment strategies for diseases of the thyroid.

OBJECTIVE

To review the literature concerning the role of angiogenesis in the thyroid gland.

CONCLUSIONS

Angiogenesis is an important process which has been shown to be involved in the pathophysiology of benign and malignant diseases of the thyroid gland. Manipulation of this process holds great promise for the development of novel treatments for these disorders. As the mechanisms regulating angiogenesis in the thyroid become increasingly clear, researchers will come ever closer to turning this promise into clinical reality.