Effects of PTK787/ZK222584, a tyrosine kinase inhibitor, on the growth of a poorly differentiated thyroid carcinoma: an animal study

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.

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.

Selective use of vandetanib in the treatment of thyroid cancer

Vandetanib is a once-daily orally available tyrosine kinase inhibitor that works by blocking RET (REarranged during Transfection), vascular endothelial growth factor receptor (VEGFR-2, VEGFR-3), and epidermal growth factor receptor and to a lesser extent VEGFR-1, which are important targets in thyroid cancer (TC). It is emerging as a potentially effective option in the treatment of advanced medullary thyroid cancer (MTC) and in dedifferentiated papillary thyroid cancer not responsive to radioiodine. The most important effect of vandetanib in aggressive MTC is a prolongation of progression-free survival and a stabilization of the disease. Significant side effects have been observed with the vandetanib therapy (as fatigue, hypertension, QTc prolongation, cutaneous rash, hand-and-foot syndrome, diarrhea, etc), and severe side effects can require the suspension of the drug. Several studies are currently under way to evaluate the long-term efficacy and tolerability of vandetanib in MTC and in dedifferentiated papillary TC. The efficacy of vandetanib in patients with MTC in long-term treatments could be overcome by the resistance to the drug. However, the effectiveness of the treatment could be ameliorated by the molecular characterization of the tumor and by the possibility to test the sensitivity of primary TC cells from each subject to different tyrosine kinase inhibitor. Association studies are evaluating the effect of the association of vandetanib with other antineoplastic agents (such as irinotecan, bortezomib, etc). Further research is needed to determine the ideal therapy to obtain the best response in terms of survival and quality of life.

Dynamic contrast-enhanced MRI parameters as biomarkers for the effect of vatalanib in patients with non-small-cell lung cancer

ABSTRACT: 

Aims: To assess the utility of dynamic contrast-enhanced MRI parameters in the demonstration of early antiangiogenic effects and as prognostic biomarkers in second-line treatment of advanced-stage non-small-cell lung cancer with vatalanib. Patients & methods: The transfer constant (Ktrans) and the initial area under the contrast concentration–time curve at 60 s (AUC60) were assessed in 46 patients. Changes were compared with response evaluation from computed tomography imaging and Response Evaluation Criteria In Solid Tumors guidelines. Results: Statistically significant mean reductions in Ktrans (38.4%; p < 0.0001) and AUC60 (24.9%; p < 0.0001) were found at day 2. After 12 weeks, 16 patients (35%) demonstrated stable disease and 30 (65%) demonstrated progressive disease. No statistically significant differences in day 2 Ktrans and AUC60 reductions between stable disease and progressive disease patients were found. Conclusion: Dynamic contrast-enhanced MRI can demonstrate a statistically significant reduction in vascular parameters of non-small-cell lung cancer, but does not predict patient outcome.

Biomarkers for anti-angiogenic therapy in cancer

Angiogenesis, the development of new vessels from existing vasculature, plays a central role in tumor growth, survival, and progression. On the molecular level it is controlled by a number of pro- and anti-angiogenic cytokines, among which the vascular endothelial growth factors (VEGFs), together with their related VEGF-receptors, have an exceptional position. Therefore, the blockade of VEGF signaling in order to inhibit angiogenesis was deemed an attractive approach for cancer therapy and drugs interfering with the VEGF-ligands, the VEGF receptors, and the intracellular VEGF-mediated signal transduction were developed. Although promising in pre-clinical trials, VEGF-inhibition proved to be problematic in the clinical context. One major drawback was the generally high variability in patient response to anti-angiogenic drugs and the rapid development of therapy resistance, so that, in total, only moderate effects on progression-free and overall survival were observed. Biomarkers predicting the response to VEGF-inhibition might attenuate this problem and help to further individualize drug and dosage determination. Although up to now no definitive biomarker has been identified for this purpose, several candidates are currently under investigation. This review aims to give an overview of the recent developments in this field, focusing on the most prevalent tumor species.

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.

Molecular Therapies in Thyroid Cancer

Thyroid cancer is a common diagnosis with greater than 34,000 cases per year in the United States. Early stage thyroid cancer is often managed with surgical intervention and radioactive iodine; however, for recurrent or metastatic disease, the treatment options, historically, have been limited to chemotherapy. Chemotherapy for metastatic thyroid cancer has been of limited efficacy. Encouragingly, molecular therapeutics have played a greater role in managing patients with advanced disease. These agents work primarily through disruption of tyrosine kinase pathways. This review will discuss the expanding role of molecular targets in managing patients with advanced thyroid cancer.

New targeted molecular therapies for dedifferentiated thyroid cancer

Dedifferentiated thyroid cancer (DeTC) derived from follicular epithelium is often incurable because it does not respond to radioiodine, radiotherapy, or chemotherapy. In cases, RET/PTC rearrangements are found in 30%–40%, RAS mutations in about 10%, and BRAF mutations in around 40%–50%, with no overlap between these mutations results in papillary thyroid cancer, while a higher prevalence of BRAF mutations (up to 70%) has been observed in DeTC. The identification of these activating mutations in DeTC makes this malignancy an excellent model to examine the effect of tyrosine kinase inhibitors (TKIs). Clinical trials with several TKIs targeting RET, and to a lesser extent BRAF, and other TKRs have shown positive results, with about one-third of DeTC showing a reduction in tumor size up to 50%, with the longest treatment duration of approximately three-four years. Angiogenesis inhibitors have also shown promising activity in DeTC. Progress is being made toward effective targeted DeTC therapy. The possibility of testing the sensitivity of primary DeTC cells from each subject to different TKIs could increase the effectiveness of the treatment.

A delayed type of three-dimensional growth of human endothelial cells under simulated weightlessness

Endothelial cells (ECs) form three-dimensional (3D) aggregates without any scaffold when they are exposed to microgravity simulated by a random positioning machine (RPM) but not under static conditions at gravity. Here we describe a delayed type of formation of 3D structures of ECs that was initiated when ECs cultured on a desktop RPM remained adherent for the first 5 days but spread over neighboring adherent cells, forming little colonies. After 2 weeks, tube-like structures (TSs) became visible in these cultures. They included a lumen, and they elongated during another 2 weeks of culturing. The walls of these TSs consisted mainly of single-layered ECs, which had produced significantly more beta(1)-integrin, laminin, fibronectin, and alpha-tubulin than ECs simultaneously grown adhering to the culture dishes under microgravity or normal gravity. The amount of actin protein was similar in ECs incorporated in TSs and in ECs growing at gravity. The ratio of tissue inhibitor of metalloproteinases-1 to matrix metalloproteinase-2 found in the supernatants was lower at the seventh than at the 28th day of culturing. These results suggest that culturing ECs under conditions of modeled gravitational unloading represents a new technique for studying the formation of tubes that resemble vascular intimas.

Clinicopathologic and molecular disease prognostication for papillary thyroid cancer

Despite its increasing incidence over the last 30 years, the mortality rate of papillary thyroid cancer (PTC) has decreased significantly. Nevertheless, a minority of patients still present with an aggressive form of PTC that can lead to death, even after a prolonged period of survival. Many classifications exist that allow one to stratify the clinical risk of recurrence and death in patients with PTC; however, the parameters upon which they are established are pathological and molecular and, therefore, are revealed only after surgery. The preoperative identification of these aggressive variants of PTC would allow one to schedule a more aggressive operation (e.g., total thyroidectomy together with central and/or mono- or bi-lateral node dissections) in patients with high-risk PTC. This article reviews the parameters used most commonly to differentiate low-risk PTCs from their more aggressive variants and describes some of the newest molecular therapies for this latter group of tumors.

Clinical implications of molecular markers in follicular cell-derived thyroid cancer

The increasing use/applications of molecular biology techniques have provided new insights on the genetic changes that underlie carcinogenesis and tumor progression in thyroid cancer. Molecular analysis may improve the histopathologic evaluation of follicular cell-derived thyroid carcinoma, not only elucidating some unresolved problems related to the diagnosis and disease prognosis, but also by improving patient management. Besides increasing our comprehension of cancer biology, either genetic alterations or gene expression profiles implicated in thyroid carcinogenesis shed new light on innovative diagnostic procedures as well as on targeted therapies.

Receptor tyrosine kinase inhibitors in thyroid cancer

Thyroid cancer is frequently associated with the oncogenic conversion of receptor tyrosine kinases (RTKs) or their downstream signalling molecules. Hence, there is a strong biological rationale for assessing the efficacy of RTK blockade to treat patients who are resistant to or not candidates for treatment with radioactive iodine. The first results of clinical trials based on the use of RTK inhibitors in thyroid cancer patients have recently been published. Here we discuss targeting of specific RTKs as a potential therapeutic strategy for the treatment of thyroid cancer.

Dedifferentiated thyroid cancer: a therapeutic challenge

Human papillary dedifferentiated thyroid cancer (HPDTC) represents a therapeutic dilemma. Targeted therapy (RET proto-oncogene or BRAF-targeting drugs) are promising treatments for HPDTC. Also PPARg agonists are another exciting field for redifferentiating therapy of HPDTC. However, even if many new approaches for the therapy of HPDTC are emerging, until now a significant clinical impact on survival by the use of these drugs is still lacking. In the future, the identification of patients who are likely to benefit from each therapeutic option will be important. In this view particular importance should be given to development of primary cells from the single patient by fine needle aspiration samples, as recently observed in anaplastic thyroid cancer. In fact, chemosensitivity tests in primary tumoral cells may help in detecting responsive patients and in preventing the administration of inactive drugs to those unresponsive.

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.

Axitinib is an active treatment for all histologic subtypes of advanced thyroid cancer: results from a phase II study

PURPOSE

Patients with advanced, incurable thyroid cancer not amenable to surgery or radioactive iodine ((131)I) therapy have few satisfactory therapeutic options. This multi-institutional study assessed the activity and safety of axitinib, an oral, potent, and selective inhibitor of vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3 in patients with advanced thyroid cancer.

PATIENTS AND METHODS

Patients with thyroid cancer of any histology that was resistant or not appropriate for (131)I were enrolled onto a single-arm phase II trial to receive axitinib orally (starting dose, 5 mg twice daily). Objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors was the primary end point. Secondary end points included duration of response, progression-free survival (PFS), overall survival, safety, and modulation of soluble (s) VEGFR.

RESULTS

Sixty patients were enrolled. Partial responses were observed in 18 patients, yielding an ORR of 30% (95% CI, 18.9 to 43.2). Stable disease lasting > or = 16 weeks was reported in another 23 patients (38%).

OBJECTIVE

responses were noted in all histologic subtypes. Median PFS was 18.1 months (95% CI, 12.1 to not estimable). Axitinib was generally well tolerated, with the most common grade > or = 3 treatment-related adverse event being hypertension (n = 7; 12%). Eight patients (13%) discontinued treatment because of adverse events. Axitinib selectively decreased sVEGFR-2 and sVEGFR-3 plasma concentrations versus sKIT, demonstrating its targeting of VEGFR.

CONCLUSION

Axitinib is a selective inhibitor of VEGFR with compelling antitumor activity in all histologic subtypes of advanced thyroid cancer.

[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.

PTK787/ZK 222584, a small molecule tyrosine kinase receptor inhibitor of vascular endothelial growth factor (VEGF), has modest activity in myelofibrosis with myeloid metaplasia

Angiogenesis is part of the pathophysiology of myelofibrosis with myeloid metaplasia (MMM). PTK787/ZK 222584 (PTK/ZK) is a novel inhibitor of vascular endothelial growth factor receptors. Twenty-nine patients with MMM received a continuous dosing schedule of PTK/ZK doses of 500 or 750 mg twice daily (BID). Transient potentially PTK/ZK related mild nausea, vomiting, dizziness, fatigue, thrombocytopenia, or anorexia occurred in 15% of patients. Dose limiting toxicities of dyspepsia, proteinurea, and/or mucositis were observed in patients treated with 750 mg BID. One (3%) and five (17%) patients achieved complete remission and clinical improvement, respectively. PTK/ZK has modest activity in patients with MMM.

Sorafenib inhibits the angiogenesis and growth of orthotopic anaplastic thyroid carcinoma xenografts in nude mice

Anaplastic thyroid carcinoma (ATC) remains one of the most lethal human cancers. We hypothesized that sorafenib, a multikinase inhibitor of the BRaf, vascular endothelial growth factor receptor-2, and platelet-derived growth factor receptor-beta kinase, would decrease tumor growth and angiogenesis in an orthotopic model of ATC. The in vitro antiproliferative and proapoptotic effects of sorafenib on ATC cell lines were examined. To study the in vivo effects of sorafenib on orthotopic ATC tumors in nude mice, sorafenib was given p.o. at 40 or 80 mg/kg daily. Intratumoral effects were studied using immunohistochemical analysis. The effect of sorafenib on survival of the mice was also studied. Sorafenib inhibited the in vitro proliferation of ATC cell lines. Sorafenib also significantly inhibited tumor angiogenesis via the induction of endothelial apoptosis in an orthotopic model of thyroid cancer. As result, the growth of orthotopic ATC xenografts was reduced and the survival of the test animals was improved. Sorafenib exerts significant antitumor activity in an orthotopic xenograft model of ATC via a potent antiangiogenic effect. The antiangiogenic effects of sorafenib suggest that its use in clinical setting may not depend on the BRAF mutational status of thyroid tumors. Given the lack of curative options for patients with ATC, sorafenib warrants further study as a therapeutic agent against ATC.

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.

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.

High doses of tyrosine kinase inhibitor PTK787 enhance the efficacy of ischemic hypoxia for the treatment of hepatocellular carcinoma: dual effects on cancer cell and angiogenesis

The present study aimed to investigate the therapeutic efficacy of combining vascular endothelial growth factor (VEGF) receptor blockade using tyrosine kinase inhibitor PTK787 with hypoxia for the treatment of hepatocellular carcinoma (HCC). The in vivo effects of the treatments were determined in a rat orthotopic HCC model, in which hypoxia was generated by hepatic artery ligation (HAL). Compared with HAL alone, PTK787 combined with HAL significantly prolonged the animal survival, reduced the tumor size, induced more tumor tissue necrosis and apoptosis, and down-regulated the expression of von Willebrand factor. The mechanism was explored in vitro using murine HCC and endothelial cell lines, respectively. PTK787 combined with hypoxia decreased the expression of VEGF and VEGF receptors in both cell lines and suppressed the cell viability by induction of cell cycle arrest and promotion of apoptosis. Up-regulation of cleaved form caspase-9 and down-regulation of Bcl-2 and cyclin D1 were detected with the combined treatment. Hypoxia sensitized endothelial cells to the inhibitory effect of PTK787 on forming tubular-like structure. The motility of tumor cells was inhibited by hypoxia and the combined approach, with down-regulation of Rac1, Rho, and phosphorylated Akt expression. However, in the endothelial cells, the combined treatment inhibited the hypoxia-enhanced cell motility, with suppressed Rac1, Rho, and phosphorylated Akt expression. In conclusion, PTK787 combined with hypoxia achieved a better therapeutic efficacy than hypoxia alone through enhancing hypoxia-induced antitumor cell effect and preventing the activation of angiogenic process.

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.

Drug insight: Small-molecule inhibitors of protein kinases in the treatment of thyroid cancer

Molecular targeting of protein kinases is a new paradigm in the treatment of cancer. The clinical efficacy of low-molecular weight inhibitors of ABL, stem-cell growth-factor receptor, and the epidermal growth factor receptor in different tumor types is witness to the power of this approach. The presence of activating mutations of a kinase, or an increased gene copy number, might anticipate tumor responsiveness to its targeting. Thyroid cancer is the most prevalent endocrine malignancy and is frequently associated with the oncogenic conversion of two specific protein kinases, RET and BRAF. Small-molecule inhibitors of both kinases have already reached the clinical testing stage. Protein kinases other than RET and BRAF are also being evaluated for their potential in thyroid-cancer treatment.

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.

New molecular targeted therapies in thyroid cancer

Carcinoma of the thyroid gland is the most common malignancy of the endocrine system. Differentiated tumors are often curable with surgical resection and radioactive iodine. A small percentage of such patients, however, do not undergo remission and need new therapeutic approaches. Both anaplastic and medullary thyroid carcinomas exhibit aggressive behavior and are usually resistant to current therapeutic modalities. Thyroid carcinoma represents a fascinating model and a particularly promising paradigm for targeted therapy because some of the key oncogenic events are activating mutations of genes coding for tyrosine kinases, and these occur early in cancer development. A prototype is the RET proto-oncogene, a receptor tyrosine kinase, which is a key regulator of development and a 'hotspot' for oncogenic mutations. Mutations in the RET proto-oncogene have been identified as causative for papillary carcinoma and familial medullary thyroid carcinoma, making it an attractive target for selective inhibition in these subtypes. ZD 6474 has shown promising activity in preclinical models against RET kinase, and its contemporary inhibition of vascular endothelial growth factor and epidermal growth factor pathways renders it a very attractive drug for clinical trials in thyroid cancer. Activating point mutation of B-RAF can occur early in the development of papillary carcinoma. Moreover, papillary carcinomas with these mutations have more aggressive properties and are diagnosed more often at an advanced stage. Clinical evaluation of B-RAF-targeting drugs is undergoing and trials in thyroid cancer are planned. Agents that restore radioiodine uptake, such as histone deacetylase inhibitors and retinoids, represent another exciting field in new drug development in thyroid cancer.

Dual Epidermal Growth Factor Receptor and Vascular Endothelial Growth Factor Receptor Inhibition with NVP-AEE788 for the Treatment of Aggressive Follicular Thyroid Cancer

PURPOSE

Patients with radioiodine-resistant follicular thyroid cancer (FTC) have a poor prognosis, if metastasized, with currently available treatment modalities. Epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) and their receptors (EGFR and VEGFR) have been reported to be overexpressed in FTC and have been implicated in FTC development. We hypothesized that inhibiting the phosphorylation of EGFR and VEGFR by treatment with NVP-AEE788 (AEE788), a novel dual specific EGFR and VEGFR inhibitor, either alone or in combination with paclitaxel, would inhibit the growth of FTC xenografts in an orthotopic nude mouse model.

EXPERIMENTAL DESIGN

To confirm previous reports, EGF and EGFR expression and vascularity were analyzed in human samples of FTC, Hürthle cell carcinoma, and normal thyroid tissues. EGFR expression in four FTC cell lines was measured using Western blotting. The antitumor effect of AEE788 on FTC cells in vitro was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and Western blotting. The effect of AEE788, alone and in combination with paclitaxel, on FTC tumor growth in an orthotopic nude mouse model was also investigated. Immunohistochemical analysis of EGFR and VEGFR signaling status, cell proliferation, apoptosis, and microvessel density was done.

RESULTS

EGF, EGFR, and vascularity were increased in human thyroid tumor samples and EGFR was increased in FTC cells. AEE788 inhibited FTC cell growth in vitro and reduced the phosphorylation status of EGFR, VEGFR, and two downstream targets, AKT and mitogen-activated protein kinase, in FTC cells. AEE788 alone and, to a greater extent, AEE788 plus paclitaxel suppressed FTC tumor growth in the thyroids of nude mice.

CONCLUSION

Dual inhibition of EGFR and VEGFR by AEE788 could represent a novel approach to the treatment of radioiodine-resistant FTC.

Drugs to suppress cough

Cough is an important defensive reflex of the airway and also a common symptom of respiratory disease. Cough after common respiratory virus infection is transient but is more persistent when associated with conditions such as asthma, rhinosinusitis, gastro-oesophageal reflux, chronic obstructive pulmonary disease and lung cancer. Persistent cough may be due to peripheral and/or central sensitisation of cough reflexes initiated by cough receptors, rapidly adapting receptors or nociceptors. Treatment directed at associated conditions such as asthma (with anti-inflammatories) and gastro-oesophageal reflux (with proton-pump inhibitors) improve cough. There remains a need to use drugs that suppress the neural activity of cough (termed nonspecific), as treatments directed at the clinical cause(s) of the underlying cough (termed specific) may not be effective. The most effective indirect antitussives are opioids such as morphine, codeine or pholcodeine, but they produce side effects such as drowsiness, nausea, constipation and physical dependence. Opioids such as kappa- and delta-receptor agonists, non-opioids such as nociceptin, neurokinin and bradykinin receptor antagonists, cannabinoids, vanilloid receptor-1 antagonists, blockers of Na+-dependent channels, and large conductance Ca2+-dependent K+-channel activators of afferent nerves may represent novel antitussives.

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.

Opportunities for targeted therapies in hepatocellular carcinoma

Hepatocellular cancer (HCC) is the fifth most common solid tumor worldwide, accounting for 500,000 new cases annually. Although less common in the United States, HCC is expected to increase in incidence over the next two decades largely because of the prevalence of hepatitis C virus infection. A majority of patients present with advanced disease and are not candidates for liver transplantation, surgical resection, or regional therapy. In 60% to 80% of patients with HCC, treatment is complicated by underlying liver cirrhosis and hepatic dysfunction. Systemic treatments are minimally effective, can have significant toxicity, and have not been shown to improve patient survival. New approaches targeting molecular abnormalities specific to HCC are needed to improve patient outcome. This review summarizes the state of knowledge of those key aspects of the molecular pathogenesis of HCC that may represent rational therapeutic targets in this disease. Relevant preclinical and clinical information on novel compounds directed toward abnormalities in HCC is reviewed.

Regulators of angiogenesis and strategies for their therapeutic manipulation

Angiogenesis provides a mechanism by which delivery of oxygen and nutrients is adapted to compliment changes in tissue mass or metabolic activity. However, maladaptive angiogenesis is integral to the process of several diseases common in Western countries, including tumor growth, vascular insufficiency, diabetic retinopathy and rheumatoid arthritis. Understanding the process of capillary growth, including the identification and functional analyses of key pro- and anti-angiogenic factors, provides knowledge that can be applied to improve/reverse these pathological states. Initially, angiogenesis research focused predominantly on vascular endothelial growth factor (VEGF) as a main player in the angiogenesis cascade. It is apparent now that participation of multiple angiogenic factors and signal pathways is critical to enable effective growth and maturation of nascent capillaries. The purpose of this review is to focus on recent progress in identifying angiogenesis signaling pathways that show promise as targets for successful induction or inhibition of capillary growth. The strategies applied to achieve these contradictory tasks are discussed within the framework of our existing fundamental knowledge of angiogenesis signaling cascades, with an emphasis on comparing the employment of distinctive tactics in modulation of these pathways. Innovative developments that are presented include: (1) inducing a pleiotropic response via activation or inhibition of angiogenic transcription factors; (2) modulation of nitric oxide tissue concentration; (3) manipulating the kallikrein-kinin system; (4) use of endothelial progenitor cells as a means to either directly contribute to capillary growth or to be used as a vehicle to deliver "suicide genes" to tumor tissue.

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.

Both antiangiogenesis- and angiogenesis-independent effects are responsible for hepatocellular carcinoma growth arrest by tyrosine kinase inhibitor PTK787/ZK222584

Vascular endothelial growth factor (VEGF) plays an important role in tumor angiogenesis of hepatocellular carcinoma. Inhibition of VEGF receptors could theoretically reduce angiogenesis and tumor growth in hepatocellular carcinoma, but this remains to be proven with an experimental study. This study examined the angiogenesis-dependent and angiogenesis-independent activities of PTK787/ZK222584 (PTK787), a tyrosine kinase inhibitor of VEGF receptors, in nude mice bearing human hepatocellular carcinoma xenografts. The in vitro effects of PTK787 on proliferation, apoptosis, and cell cycle distribution in human hepatocellular carcinoma cell lines were also studied. Oral administration of PTK787 resulted in a significant reduction in tumor volume and microvessel formation of hepatocellular carcinoma xenografts in nude mice. PTK787 inhibited tumor cell proliferation in a dose-dependent manner and also induced tumor cells to undergo apoptosis both in vivo and in vitro. The proapoptotic response was associated with down-regulation of Bcl-2 and Bcl-x(L) expression and induction of cleavage of caspase-3. In addition, PTK787 induced growth arrest in hepatocellular carcinoma cells, which was associated with G1 arrest and partial G2-M block. This effect correlated with an increase in p21(WAF1/ CIP1) (p21) and p27KIP1 (p27) protein expression. In conclusion, this study showed that PTK787 is a potent inhibitor of tumor growth in hepatocellular carcinoma by both antiangiogenic effect and direct effects on tumor cell proliferation and apoptosis. Our data suggest that blockage of VEGF receptors may provide an effective therapeutic approach for human hepatocellular carcinoma.

Intraluminal Application of Vascular Endothelial Growth Factor Enhances Healing of Microvascular Anastomosis in a Rat Model

BACKGROUND

Early reconstitution after injury to the endothelium is an important feature for reducing a number of vessel wall pathologies. We investigated the effect of vascular endothelial growth factor (VEGF) and its impact on the vascular remodeling process and reendothelialization after microsurgery.

METHODS AND RESULTS

Microvascular anastomosis was performed in the rat femoral artery. One group was treated with intraluminal administration of VEGF and the other with vehicle. We investigated morphological, ultrastructural and immunohistochemical changes of the vascular wall and the reendothelialization process. After 10 days, reendothelialization was significantly faster in VEGF-treated rats. Transmission electron microscopy revealed a complete healing in contrast to vehicle-treated vessels. Moreover, extracellular matrix proteins, such as fibronectin, collagen types I, III and IV, were significantly increased. Furthermore, VEGF treatment significantly induced VEGF receptor 2, flk-1, osteopontin and TGF-beta(1) proteins.

CONCLUSIONS

Our data clearly document for the first time that intraluminal treatment with VEGF is beneficial to the healing process in vascular microsurgery. Osteopontin and TGF-beta(1), both induced by VEGF, may play an important role in the vascular remodeling process. Our results provide clear evidence that VEGF application may represent a useful strategy in accelerating reendothelialization and improving vascular healing after microsurgery.

Modern approaches to age-old questions about thyroid tumors

There is a compelling need for improvement in the diagnosis of thyroid nodules, in predicting thyroid cancer prognosis and, in the treatment of recurrent well-differentiated and anaplastic thyroid cancer. In this review we discuss the impact of genomic technologies such as microarrays, SAGE, and proteomics on the diagnosis, prognosis and treatment of thyroid cancer. Gene expression profiling using these technologies has shown promising results in the molecular classification of different types of cancer, including thyroid. Furthermore, microarrays have been successfully used to identify prognostic markers in other cancer-types, offering the possibility to better tailor thyroid cancer treatment schemes. Lastly, novel therapeutic targeting against tyrosine kinases have shown promising results in the treatment of several cancers and might prove to be beneficial for patients with recurrent or undifferentiated thyroid cancer.

Antivascular Therapy of Human Follicular Thyroid Cancer Experimental Bone Metastasis by Blockade of Epidermal Growth Factor Receptor and Vascular Growth Factor Receptor Phosphorylation

Patients suffering from bone metastases of follicular thyroid carcinoma (FTC) have a poor prognosis because of the lack of effective treatment strategies. The overexpression of epidermal growth factor receptor (EGFR) associated with increased vascularity has been implicated in the pathogenesis of FTC and subsequent bone metastases. We hypothesized that inhibiting the phosphorylation of the EGFR and vascular endothelial growth factor receptor (VEGFR) by AEE788, a dual tyrosine kinase inhibitor of EGFR and VEGFR, in combination with paclitaxel would inhibit experimental FTC bone lesions and preserve bone structure. We tested this hypothesis using the human WRO FTC cell line. In culture, AEE788 inhibited the EGF-mediated phosphorylation of EGFR, VEGFR2, mitogen-activated protein kinase, and Akt in culture. AEE788, alone and in combination with paclitaxel, inhibited cell growth and induced apoptosis. When WRO cells were injected into the tibia of nude mice, tumor and endothelial cells within the lesions expressed phosphorylated EGFR, VEGFR, Akt, and mitogen-activated protein kinase that were inhibited by the oral administration of AEE788. Therapy consisting of orally given AEE788 and i.p. injected paclitaxel induced a high level of apoptosis in tumor-associated endothelial cells and tumor cells with the inhibition of tumor growth in the bone and the preservation of bone structure. Collectively, these data show that blocking the phosphorylation of EGFR and VEGFR with AEE788 combined with paclitaxel can significantly inhibit experimental human FTC in the bone of nude mice.

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.

New antiangiogenic strategies for the treatment of proliferative synovitis

Angiogenesis inhibition, which has been extensively studied for the treatment of various malignancies, is beginning to emerge as a new potential therapy for proliferative synovitis, particularly rheumatoid arthritis (RA). The rheumatoid pannus, the site of inflammation and joint destruction in the rheumatoid synovium, relies on the development of new vasculature to sustain its growth. A host of mediators have been shown to induce angiogenesis at the site of the inflamed synovium; these include vascular endothelial growth factor, fibroblast growth factor, integrin alpha(V)beta3, angiopoietin, prosta-glandin E1 and prostaglandin E2, and matrix metalloproteinases. In addition, hypoxia at the site of synovial inflammation contributes to angiogenesis stimulation. Several naturally-occurring inhibitors exist, such angiostatin and endostatin. There are a number of drugs undergoing study in the treatment of proliferative synovitis, which capitalise on the correlation between angiogenesis inhibition and the reduction of signs and symptoms of RA. Paclitaxel and an anti-integrin alpha(V)beta3 antibody, LM-609, are currently in clinical trials. Other drugs that may inhibit angiogenesis in RA include TNP-470 (formerly called AGM-1470), PPI-2458, PTK-787, bevacizumab and thalidomide. Many of these drugs have shown promise for the treatment of oncologic disorders, and are now being evaluated for the treatment of proliferative synovitis.

Vascular endothelial growth factor and other signaling pathways in developmental and pathologic angiogenesis

The field of angiogenesis received a huge boost in 2003 with the announcement of positive results in a phase III clinical trial using a vascular endothelial growth factor (VEGF)-blocking antibody for the treatment of cancer. Although the VEGF pathway has emerged as a central signaling pathway in normal and pathologic angiogenesis, several other pathways are also now recognized as playing essential roles. This review focuses on 2 specific areas. First, we summarize some of the work on newly discovered angiogenic signaling pathways by primarily describing the molecular biology of the pathways and the evidence for their involvement in vascular development. Second, we describe progress in therapeutic antiangiogenesis in cancer, particularly with agents that block the VEGF pathway.

Vascular endothelial growth factor: basic science and clinical progress

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in a variety of in vivo models. Hypoxia has been shown to be a major inducer of VEGF gene transcription. The tyrosine kinases Flt-1 (VEGFR-1) and Flk-1/KDR (VEGFR-2) are high-affinity VEGF receptors. The role of VEGF in developmental angiogenesis is emphasized by the finding that loss of a single VEGF allele results in defective vascularization and early embryonic lethality. VEGF is critical also for reproductive and bone angiogenesis. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. In situ hybridization studies demonstrate expression of VEGF mRNA in the majority of human tumors. Anti-VEGF monoclonal antibodies and other VEGF inhibitors block the growth of several tumor cell lines in nude mice. Clinical trials with various VEGF inhibitors in a variety of malignancies are ongoing. Very recently, an anti-VEGF monoclonal antibody (bevacizumab; Avastin) has been approved by the Food and Drug Administration as a first-line treatment for metastatic colorectal cancer in combination with chemotherapy. Furthermore, VEGF is implicated in intraocular neovascularization associated with diabetic retinopathy and age-related macular degeneration.

Reference Systems for Kinase Drug Discovery: Chemical Genetic Approaches to Cell-Based Assays

Protein kinases play key roles in a number of diseases, including cancer, inflammation, and diabetes. Disregulation of kinase-based signal transduction networks results in aberrant cell differentiation, activation, proliferation, and invasion. The growing importance of kinases as a major class of drug targets across multiple large clinical indications, together with the large number of kinases in the genome (~518), has generated a critical need for technologies that enable the identification of potent and selective kinase inhibitors with good drug-like properties. In this review, we describe methods used for developing cell-based assays for kinase inhibitors, discuss advantages and disadvantages of each approach, and describe new chemical genetic methods as reference systems for establishing cell-based assays and their use for functional selectivity profiling of kinase inhibitors.