A phase II trial of fosbretabulin in advanced anaplastic thyroid carcinoma and correlation of baseline serum-soluble intracellular adhesion molecule-1 with outcome

Signaling Pathways in Thyroid Cancer and Their Therapeutic Implications

Thyroid cancer is a common malignancy of endocrine system, and has now become the fastest increasing cancer among all the malignancies. The development, progression, invasion, and metastasis are closely associated with multiple signaling pathways and the functions of related molecules, such as Src, Janus kinase (JAK)-signal transducers and activators of transcription (STAT), mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt, NF-κB, thyroid stimulating hormone receptor (TSHR), Wnt-β-catenin and Notch signaling pathways. Each of the signaling pathways could exert its function singly or through network with other pathways. These pathways could cooperate, promote, antagonize, or interact with each other to form a complex network for the regulation. Dysfunction of this network could increase the development, progression, invasion, and metastasis of thyroid cancer. Inoperable thyroid cancer still has a poor prognosis. However, signaling pathway-related targeted therapies offer the hope of longer quality of meaningful life for this small group of patients. Signaling pathway-related targets provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer. In the present work, the advances in these signaling pathways and targeted treatments of thyroid cancer were reviewed.

Anaplastic thyroid carcinoma: Failure of conventional therapy but hope of targeted therapy

BACKGROUND

Anaplastic thyroid cancer has a median survival between 1.2 and 10 months. The purpose of our study was to evaluate the outcomes of patients with anaplastic thyroid cancer in Ireland.

METHODS

We carried out a retrospective analysis of the Irish National Cancer Database for patients with anaplastic thyroid cancer between 2000 and 2010.

RESULTS

Of a total of 64 patients (40 women, 24 men), the median age was 69 years, and 29.7% of the patients had distant metastases. The overall median survival was 2.3 months and the 1, 2, and 5-year survival was 12.5%, 6.25%, and 4.69%, respectively. On univariate analysis age, sex, metastases at diagnosis, and multimodality treatment were statistically significant indicators of prognosis, and metastases at diagnosis remained statistically significant on multivariate analysis.

CONCLUSION

These results correlate with the American Thyroid Association (ATA) guidelines, in which, when possible, multimodality therapy offers a survival advantage to a select group of patients. Novel therapies may offer the greatest hope for these patients. © 2016 Wiley Periodicals, Inc. Head Neck 38: E1122-E1129, 2016.

Valproic Acid, a Histone Deacetylase Inhibitor, in Combination with Paclitaxel for Anaplastic Thyroid Cancer: Results of a Multicenter Randomized Controlled Phase II/III Trial

Anaplastic thyroid cancer (ATC) has a median survival less than 5 months and, to date, no effective therapy exists. Taxanes have recently been stated as the main drug treatment for ATC, and the histone deacetylase inhibitor valproic acid efficiently potentiates the effects of paclitaxel in vitro. Based on these data, this trial assessed the efficacy and safety of the combination of paclitaxel and valproic acid for the treatment of ATC. This was a randomized, controlled phase II/III trial, performed on 25 ATC patients across 5 centers in northwest Italy. The experimental arm received the combination of paclitaxel (80 mg/m²/weekly) and valproic acid (1,000 mg/day); the control arm received paclitaxel alone. Overall survival and disease progression, evaluated in terms of progression-free survival, were the primary outcomes. The secondary outcome was the pharmacokinetics of paclitaxel. The coadministration of valproic acid did not influence the pharmacokinetics of paclitaxel. Neither median survival nor median time to progression was statistically different in the two arms. Median survival of operated-on patients was significantly better than that of patients who were not operated on. The present trial demonstrates that the addition of valproic acid to paclitaxel has no effect on overall survival and disease progression of ATC patients. This trial is registered with EudraCT 2008-005221-11.

Translational aspects in targeting the stromal tumour microenvironment: from bench to bedside

Solid tumours comprise, not only malignant cells but also a variety of stromal cells and extracellular matrix proteins. These components interact via an array of signalling pathways to create an adaptable network that may act to promote or suppress cancer progression. To date, the majority of anti-tumour chemotherapeutic agents have principally sought to target the cancer cell. Consequently, resistance develops because of clonal evolution, as a result of selection pressure during tumour expansion. The concept of activating or inhibiting other cell types within the tumour microenvironment is relatively novel and has the advantage of targeting cells which are genetically stable and less likely to develop resistance. This review outlines key players in the stromal tumour microenvironment and discusses potential targeting strategies that may offer therapeutic benefit.

The genomic and transcriptomic landscape of anaplastic thyroid cancer: implications for therapy

BACKGROUND

Anaplastic thyroid carcinoma is the most undifferentiated form of thyroid cancer and one of the deadliest of all adult solid malignancies. Here we report the first genomic and transcriptomic profile of anaplastic thyroid cancer including those of several unique cell lines and outline novel potential drivers of malignancy and targets of therapy.

METHODS

We describe whole genomic and transcriptomic profiles of 1 primary anaplastic thyroid tumor and 3 authenticated cell lines. Those profiles augmented by the transcriptomes of 4 additional and unique cell lines were compared to 58 pairs of papillary thyroid carcinoma and matched normal tissue transcriptomes from The Cancer Genome Atlas study.

RESULTS

The most prevalent mutations were those of TP53 and BRAF; repeated alterations of the epigenetic machinery such as frame-shift deletions of HDAC10 and EP300, loss of SMARCA2 and fusions of MECP2, BCL11A and SS18 were observed. Sequence data displayed aneuploidy and large regions of copy loss and gain in all genomes. Common regions of gain were however evident encompassing chromosomes 5p and 20q. We found novel anaplastic gene fusions including MKRN1-BRAF, FGFR2-OGDH and SS18-SLC5A11, all expressed in-frame fusions involving a known proto-oncogene. Comparison of the anaplastic thyroid cancer expression datasets with the papillary thyroid cancer and normal thyroid tissue transcriptomes suggested several known drug targets such as FGFRs, VEGFRs, KIT and RET to have lower expression levels in anaplastic specimens compared with both papillary thyroid cancers and normal tissues, confirming the observed lack of response to therapies targeting these pathways. Further integrative data analysis identified the mTOR signaling pathway as a potential therapeutic target in this disease.

CONCLUSIONS

Anaplastic thyroid carcinoma possessed heterogeneous and unique profiles revealing the significance of detailed molecular profiling of individual tumors and the treatment of each as a unique entity; the cell line sequence data promises to facilitate the more accurate and intentional drug screening studies for anaplastic thyroid cancer.

Natural Products as a Vital Source for the Discovery of Cancer Chemotherapeutic and Chemopreventive Agents

Throughout history, natural products have played a dominant role in the treatment of human ailments. For example, the legendary discovery of penicillin transformed global existence. Presently, natural products comprise a large portion of current-day pharmaceutical agents, most notably in the area of cancer therapy. Examples include Taxol, vinblastine, and camptothecin. These structurally unique agents function by novel mechanisms of action; isolation from natural sources is the only plausible method that could have led to their discovery. In addition to terrestrial plants as sources for starting materials, the marine environment (e.g., ecteinascidin 743, halichondrin B, and dolastatins), microbes (e.g., bleomycin, doxorubicin, and staurosporin), and slime molds (e.g., epothilone B) have yielded remarkable cancer chemotherapeutic agents. Irrespective of these advances, cancer remains a leading cause of death worldwide. Undoubtedly, the prevention of human cancer is highly preferable to treatment. Cancer chemoprevention, the use of vaccines or pharmaceutical agents to inhibit, retard, or reverse the process of carcinogenesis, is another important approach for easing this formidable public health burden. Similar to cancer chemotherapeutic agents, natural products play an important role in this field. There are many examples, including dietary phytochemicals such as sulforaphane and phenethyl isothiocyanate (cruciferous vegetables) and resveratrol (grapes and grape products). Overall, natural product research is a powerful approach for discovering biologically active compounds with unique structures and mechanisms of action. Given the unfathomable diversity of nature, it is reasonable to suggest that chemical leads can be generated that are capable of interacting with most or possibly all therapeutic targets.

Targeting lipid metabolism for the treatment of anaplastic thyroid carcinoma

INTRODUCTION

Anaplastic thyroid carcinoma (ATC) is the rarest subtype of thyroid cancer; however, it disproportionately accounts for a large percentage of all thyroid cancer-related deaths and is considered one of the most lethal solid tumors in humans, having a median survival of only a few months upon diagnosis. Although a variety of treatment options are available including surgery, radiation and targeted therapies, response rates are low, due in part to the drug-resistant nature of this disease; therefore, new avenues for therapeutic intervention are surely needed. Recent investigation into the metabolic profile of ATC has revealed a tumor-specific dependency for increased de novo lipogenesis, offering new insight into the molecular mechanisms that govern disease initiation and progression.

AREAS COVERED

Herein we summarize known oncogenic signaling pathways and current therapeutic strategies for the treatment of ATC. We further discuss the unique expression pattern of lipid metabolism constituents in this disease. Additionally, the current literature correlating aberrant lipogenesis with carcinogenesis is reviewed, and the implications of targeting this pathway as an innovative approach for treating ATC and other malignancies are discussed. As stearoyl-CoA desaturase (SCD) is the most differentially expressed constituent of lipid metabolism in ATC, an additional focus on this enzyme as a novel therapeutic target is applied.

EXPERT OPINION

This section is used to summarize the current research efforts underway in defining the role of lipid metabolism specifically in thyroid carcinoma. Included is a brief summary of lipid metabolism factors for which inhibitors have been generated and are under current investigation as anti-cancer agents. Finally, research limitations regarding the use of these inhibitors against components of this pathway are discussed.

Role of JNK and NF-κB in mediating the effect of combretastatin A-4 and brimamin on endothelial and carcinoma cells

PURPOSE

The 4,5-diarylimidazole brimamin is an analog of the natural vascular-disrupting agent combretastatin A-4 (CA-4) with improved water solubility, tolerance by animals and efficacy in multidrug-resistant tumors. Here, we aimed at identifying the major mechanisms underlying the in vitro and in vivo actions of brimamin on endothelial and carcinoma cells, including vascularization.

METHODS

The contribution of specific signaling kinases to the effects of brimamin on cytoskeleton organization and the viability and differentiation of endothelial cells was assessed by MTT and tube formation assays in the presence or absence of specific kinase inhibitors. Changes in DNA affinity and expression of NF-κB in endothelial and carcinoma-derived cells and their solid tumors (xenografts) treated with brimamin were ascertained by electrophoretic mobility shift assays and Western blotting. The anti-vascular effect of brimamin in solid tumors was verified by CD31 immunostaining.

RESULTS

We found that brimamin can inhibit tubulin polymerization and cause a reorganization of F-actin in Ea.hy926 endothelial cells. Its inhibitory effect on tube formation was found to depend on functional Rho kinase and JNK. JNK inhibition was found to suppress the induction of endothelial cell apoptosis by brimamin. In CA-4-refractory human BxPC-3 pancreas carcinoma-derived and triple-negative MDA-MB-231 breast carcinoma-derived cells brimamin was found to inhibit growth and to induce apoptosis at low nanomolar concentrations by blocking NF-κB activation in a dose-dependent manner. Brimamin was also found to reduce the in vivo growth rate and vascularization of MDA-MB-231 xenografts in mice. Residual tumor cells of these treated xenografts showed a relatively low expression of the p65 subunit of NF-κB.

CONCLUSIONS

Our data indicate that cellular JNK and Rho kinase activities are crucial for the cytotoxic and cytoskeleton reorganizing effects of brimamin on endothelial cells. In addition, we found that in resistant carcinoma cells and xenografts brimamin can induce down-regulation of anti-apoptotic NF-κB expression and signaling. Its chemical properties and efficacy against clinically relevant cancer entities make brimamin a promising candidate vascular-disrupting agent.

Combretastatins: more than just vascular targeting agents?

Several prodrugs of the naturally occurring combretastatins have undergone extensive clinical evaluation as vascular targeting agents (VTAs). Their increased selectivity toward endothelial cells together with their innate ability to rapidly induce vascular shutdown and inhibit tumor growth at doses up to 10-fold less than the maximum tolerated dose led to the clinical evaluation of combretastatins as VTAs. Tubulin is well established as the molecular target of the combretastatins and the vast majority of its synthetic derivatives. Furthermore, tubulin is a highly validated molecular target of many direct anticancer agents routinely used as front-line chemotherapeutics. The unique vascular targeting properties of the combretastatins have somewhat overshadowed their development as direct anticancer agents and the delineation of the various cell death pathways and anticancer properties associated with such chemotherapeutics. Moreover, the ongoing clinical trial of OXi4503 (combretastatin-A1 diphosphate) together with preliminary preclinical evaluation for the treatment of refractory acute myelogenous leukemia has successfully highlighted both the indirect and direct anticancer properties of combretastatins. In this review, we discuss the development of the combretastatins from nature to the clinic. The various mechanisms underlying combretastatin-induced cell cycle arrest, mitotic catastrophe, cell death, and survival are also reviewed in an attempt to further enhance the clinical prospects of this unique class of VTAs.

Anaplastic Thyroid Carcinoma, Version 2.2015

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Thyroid Carcinoma focuses on anaplastic carcinoma because substantial changes were made to the systemic therapy recommendations for the 2015 update. Dosages and frequency of administration are now provided, docetaxel/doxorubicin regimens were added, and single-agent cisplatin was deleted because it is not recommended for patients with advanced or metastatic anaplastic thyroid cancer.

Fosbretabulin for the treatment of anaplastic thyroid cancer

Fosbretabulin tromethamine is a vascular disrupting agent, which is a type of drug that is designed to damage the vasculature (blood vessels) of cancer tumors, causing central necrosis. This drug showed activity against anaplastic thyroid cancer that was demonstrated in orthotopic xenograft models as well as in Phase I/II trials with or without carboplatin and paclitaxel combination therapy. In all of these studies, fosbretabulin was well tolerated.

Medicinal Plants: A Potential Source of Compounds for Targeting Cell Division

Modern medicinal plant drug discovery has provided pharmacologically active compounds targeted against a multitude of conditions and diseases, such as infection, inflammation, and cancer. To date, natural products from medicinal plants remain a solid niche as a source from which cancer therapies can be derived. Among other properties, one favorable characteristic of an anticancer drug is its ability to block the uncontrollable process of cell division, as cancer cells are notorious for their abnormal cell division. There are numerous other documented works on the potential anticancer activity of drugs derived from medicinal plants, and their effects on cell division are an attractive and growing therapeutic target. Despite this, there remains a vast number of unidentified natural products that are potentially promising sources for medical applications. This mini review aims to revise the current knowledge of the effects of natural plant products on cell division.

Combretastatin A4-phosphate and its potential in veterinary oncology: a review

For many years, research on anticancer therapy has focussed almost exclusively on targeting cancer cells directly, to selectively kill them or restrict their growth. But limited advances in this strategy have led researchers to shift their attention to other potential targets. Active research is now on-going on targeting tumour stroma. Vascular disrupting agents (VDAs) appear a promising class of anticancer drugs that are currently under investigation as a sole or combined therapy in human cancer patients. This article will briefly touch on the history and biology of combretastatin A4-phosphate (CA4P) as a typical example of VDAs and will concentrate on the side effects that can be expected when used in veterinary patients. Particularly, the pathogenesis of these side effects and how they may be prevented and/or treated will be discussed. The purpose of this article is to illustrate the potentials of CA4P as anticancer therapy in veterinary oncology patients.

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.

Spanish consensus for the management of patients with anaplastic cell thyroid carcinoma

Anaplastic thyroid cancer (ATC) is the most aggressive solid tumour known and is a rare but highly lethal form of thyroid cancer that requires a multidisciplinary team approach. No Spanish consensus exists for management of patients with ATC. The Thyroid Cancer Group of the Spanish Society of Endocrinology and Nutrition and the GETHI (Grupo Español de Enfermedades Huérfanas e Infrecuentes) of the Spanish Society of Oncology, in agreement with the Boards of these Societies, commissioned an independent task force to develop a wide consensus on ATC. The relevant literature was reviewed, including serial PubMed searches supplemented with additional articles. The consensus includes the characteristics, diagnosis, initial evaluation, establishment of treatment goals, approaches to locoregional disease (surgery, radiotherapy, systemic therapy, supportive care during active treatment), approaches to advanced/metastatic disease, palliative care options, monitoring, and long-term follow-up of ATC. For operable disease, a combination of radical surgery with adjuvant radiotherapy or chemotherapy, using agents such as doxorubicin, cisplatin and paclitaxel, is the best treatment strategy. Cytotoxic drugs are poorly effective for advanced/metastatic ATC. On the other hand, targeted agents may represent a viable therapeutic option. Patients with stage IVA/IVB resectable disease have the best prognosis, particularly if a multimodal approach is used, and some stage IVB unresectable patients may respond to aggressive therapy. Patients with stage IVC disease should be considered for clinical trials or for hospice/palliative care depending on their preference. This is the first Spanish consensus for ATC, and provides recommendations for management of this extremely aggressive malignancy. Novel systemic therapies are being tested, and more effective combinations are needed to improve patient outcomes. Although more aggressive radiotherapy has reduced locoregional recurrence, mean overall survival has not improved in the past 50 years.

Design and synthesis of aminostilbene-arylpropenones as tubulin polymerization inhibitors

A series of aminostilbene-arylpropenones were designed and synthesized by Michael addition and were investigated for their cytotoxic activity against various human cancer cell lines. Some of the investigated compounds exhibited significant antiproliferative activity against a panel of 60 human cancer cell lines of the US National Cancer Institute, with 50 % growth inhibition (GI50) values in the range from < 0.01 to 19.9 μM. One of the compounds showed a broad spectrum of antiproliferative efficacy on most of the cell lines, with a GI50 value of < 0.01 μM. All of the synthesized compounds displayed cytotoxicity against A549 (non-small-cell lung cancer), HeLa (cervical carcinoma), MCF-7 (breast cancer), and HCT116 (colon carcinoma) with 50 % inhibitory concentration (IC50) values ranging from 0.011 to 8.56 μM. A cell cycle assay revealed that these compounds arrested the G2/M phase of the cell cycle. Two compounds exhibited strong inhibitory effects on tubulin assembly with IC50 values of 0.71 and 0.79 μM. Moreover, dot-blot analysis of cyclin B1 demonstrated that some of the congeners strongly induced cyclin B1 protein levels. Molecular docking studies indicated that these compounds occupy the colchicine binding site of tubulin.

Medical therapy for advanced forms of thyroid cancer

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

Survival in anaplastic thyroid cancer in relation to pre-existing goiter: a population-based study

BACKGROUND

We investigated whether pre-existent goiter and well-differentiated thyroid cancer (WDTC) are associated with survival in anaplastic thyroid carcinoma (ATC).

METHODS

We analyzed medical records from 94 ATC patients, drawn from the Netherlands Cancer Registry, diagnosed in 17 hospitals between 1989 and 2009.

RESULTS

The 29 patients (31%) with pre-existent goiter, including 8 with WDTC, were younger than those without (median, 69 vs. 76 years; P = .02). One-year overall survival was 9% (95% confidence interval [CI], 3% to 14%) with no difference between pre-existent goiter or not (overall survival, 14%; 95% CI, 1% to 26% vs overall survival, 6%; 95% CI, 0% to 13%]). Higher age was associated with a worse survival (hazard rate, 1.03; 95% CI, 1.01 to 1.06]), whereas the hazard to die was lower after surgery and/or radiotherapy (hazard rate, .37; 95% CI, .21 to .67 and hazard rate, .22; 95% CI, .12 to .41, respectively).

CONCLUSIONS

ATC patients with pre-existent goiter were younger, yet survival was not significantly different between those with or without pre-existent goiter or WDTC.

Update: the status of clinical trials with kinase inhibitors in thyroid cancer

CONTEXT

Thyroid cancer is usually cured by timely thyroidectomy; however, the treatment of patients with advanced disease is challenging because their tumors are mostly unresponsive to conventional therapies. Recently, the malignancy has attracted much interest for two reasons: the dramatic increase in its incidence over the last three decades, and the discovery of the genetic mutations or chromosomal rearrangements causing most histological types of thyroid cancer.

OBJECTIVE

This update reviews the molecular genetics of thyroid cancer and the clinical trials evaluating kinase inhibitors (KIs) in patients with locally advanced or metastatic disease. The update also reviews studies in other malignancies, which have identified mechanisms of efficacy, and also resistance, to specific KIs. This information has been critical both to the development of effective second-generation drugs and to the design of combinatorial therapeutic regimens. Finally, the update addresses the major challenges facing clinicians who seek to develop more effective therapy for patients with thyroid cancer.

RESULTS

PubMed was searched from January 2000 to November 2013 using the following terms: thyroid cancer, treatment of thyroid cancer, clinical trials in thyroid cancer, small molecule therapeutics, kinase inhibitors, and next generation sequencing.

CONCLUSIONS

A new era in cancer therapy has emerged based on the introduction of KIs for the treatment of patients with liquid and solid organ malignancies. Patients with thyroid cancer have benefited from this advance and will continue to do so with the development of drugs having greater specificity and with the implementation of clinical trials of combined therapeutics to overcome drug resistance.

Design, synthesis, and biological evaluation of novel pyridine-bridged analogues of combretastatin-A4 as anticancer agents

A series of novel pyridine-bridged analogues of combretastatin-A4 (CA-4) were designed and synthesized. As expected, the 4-atom linker configuration retained little cytotoxicities in the compounds 2e, 3e, 3g, and 4i. Activities of the analogues with 3-atom linker varied widely depending on the phenyl ring substitutions, and the 3-atom linker containing nitrogen represents the more favorable linker structure. Among them, three analogues (4h, 4s, and 4t) potently inhibited cell survival and growth, arrested cell cycle, and blocked angiogenesis and vasculature formation in vivo in ways comparable to CA-4. The superposition of 4h and 4s in the colchicine-binding pocket of tubulin shows the binding posture of CA-4, 4h, and 4s are similar, as confirmed by the competitive binding assay where the ability of the ligands to replace tubulin-bound colchicine was measured. The binding data are consistent with the observed biological activities in antiproliferation and suppression of angiogenesis but are not predictive of their antitubulin polymerization activities.

Gold(I) biscarbene complexes derived from vascular-disrupting combretastatin A-4 address different targets and show antimetastatic potential

Gold N-heterocyclic carbene (NHC) complexes are an emerging class of anticancer drugs. We present a series of gold(I) biscarbene complexes with NHC ligands derived from the plant metabolite combretastatin A-4 (CA-4) that retain its vascular-disrupting effect, yet address different cellular and protein targets. Unlike CA-4, these complexes did not interfere with tubulin, but with the actin cytoskeleton of endothelial and cancer cells. For the highly metastatic 518A2 melanoma cell line this effect was accompanied by a marked accumulation of cells in the G1 phase of the cell cycle and a suppression of active prometastatic matrix metalloproteinase-2. Despite these mechanistic differences the complexes were as strongly antivascular as CA-4 both in vitro in tube formation assays with human umbilical vein endothelial cells, and in vivo as to blood vessel disruption in the chorioallantoic membrane of chicken eggs. The antiproliferative effect of the new gold biscarbene complexes in a panel of six human cancer cell lines was impressive, with low sub-micromolar IC50 values (72 h) even against CA-4-refractory HT-29 colon and multidrug-resistant MCF-7 breast carcinoma cells. In preliminary studies with a mouse melanoma xenograft model the complexes led to significant decreases in tumor volume while being very well tolerated.

Effects of the tumor-vasculature-disrupting agent verubulin and two heteroaryl analogues on cancer cells, endothelial cells, and blood vessels

Two analogues of the discontinued tumor vascular-disrupting agent verubulin (Azixa®, MPC-6827, 1) featuring benzo-1,4-dioxan-6-yl (compound 5 a) and N-methylindol-5-yl (compound 10) residues instead of the para-anisyl group on the 4-(methylamino)-2-methylquinazoline pharmacophore, were prepared and found to exceed the antitumor efficacy of the lead compound. They were antiproliferative with single-digit nanomolar IC50 values against a panel of nine tumor cell lines, while not affecting nonmalignant fibroblasts. Indole 10 surpassed verubulin in seven tumor cell lines including colon, breast, ovarian, and germ cell cancer cell lines. In line with docking studies indicating that compound 10 may bind the colchicine binding site of tubulin more tightly (Ebind =-9.8 kcal mol(-1) ) than verubulin (Ebind =-8.3 kcal mol(-1) ), 10 suppressed the formation of vessel-like tubes in endothelial cells and destroyed the blood vessels in the chorioallantoic membrane of fertilized chicken eggs at nanomolar concentrations. When applied to nude mice bearing a highly vascularized 1411HP germ cell xenograft tumor, compound 10 displayed pronounced vascular-disrupting effects that led to hemorrhages and extensive central necrosis in the tumor.

Randomized safety and efficacy study of fosbretabulin with paclitaxel/carboplatin against anaplastic thyroid carcinoma

BACKGROUND

Anaplastic thyroid cancer (ATC), a rare highly vascularized tumor, has a dismal outcome. We conducted an open-label study of doublet carboplatin/paclitaxel chemotherapy with or without fosbretabulin in patients with ATC.

METHODS

Patients were randomly assigned in a 2:1 ratio to 6 cycles of paclitaxel 200 mg/m(2) followed by carboplatin AUC 6 on day 1 every 3 weeks (CP), or these drugs were given on day 2 after fosbretabulin 60 mg/m(2) (CP/fosbretabulin) on days 1, 8 and 15. After 6 cycles, patients on the fosbretabulin arm without progression could continue to receive fosbretabulin on days 1 and 8 of a 3-week schedule until progression. The primary end point was overall survival (OS).

RESULTS

Eighty patients were assigned (planned, 180) when enrollment was stopped due to rarity of disease and very low accrual. Median OS was 5.2 months [95% confidence interval (CI) 3.1, 9.0] for the CP/fosbretabulin arm (n=55; hazard ratio 0.73 [95% CI 0.44, 1.21]) and 4.0 months [95% CI 2.8, 6.2] for the CP arm (n=25; p=0.22 [log rank test]). One-year survival for CP/fosbretabulin versus CP was 26% versus 9%, respectively. There was no significant difference in progression-free survival between the two arms. Grade 1-2 hypertension and grade 3-4 neutropenia were more common with CP/fosbretabulin. There were no significant adverse cardiovascular side effects.

CONCLUSIONS

Although the study did not meet statistical significance in improvement in OS with the addition of fosbretabulin to carboplatin/paclitaxel, it represents the largest prospective randomized trial ever conducted in ATC. The regimen is well tolerated, with AEs and deaths primarily related to ATC and disease progression.

Vitamin D in thyroid tumorigenesis and development

Besides its classical role in bone and calcium homeostasis, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the active form of vitamin D, has many non-classical effects; antiproliferative, anti-apoptotic and prodifferentiating effects of 1,25(OH)2D3 have been described in several tumour types in preclinical models. This review focuses on the insights gained in the elucidation of the role of 1,25(OH)2D3 in the normal thyroid and in the pathogenesis, progression and treatment of thyroid cancer, the most common endocrine malignancy. An increasing amount of observations points towards a role for impaired 1,25(OH)2D3-VDR signalling in the occurrence and progression of thyroid cancer, and a potential for structural analogues in the multimodal treatment of dedifferentiated iodine-resistant thyroid cancer. A role for vitamin D in thyroid-related autoimmunity is less convincing and needs further study. Altered 1,25(OH)2D3-VDR signalling does not influence normal thyroid development nor thyrocyte function, but does affect C-cell function, at least in rodents. If these findings also apply to humans deserves further study.

Pretherapeutic drug evaluation by tumor xenografting in anaplastic thyroid cancer

BACKGROUND

Despite various attempts at modifying usual treatment modalities, anaplastic thyroid cancer (ATC) is still associated with unfavorable prognosis. Results of preclinical investigations are often of limited transferability to clinical tumor biology. Individualized multimodal treatment regimens, including novel growth-inhibiting drugs, might be a future option.

METHODS

Tumor tissue, freshly prepared from a patient operated for ATC, was xenotransplanted to nude mice. While the patient obtained a hyperfractionated external beam radiation, mice carrying xenotransplanted tumors were randomized (n = 6) and treated by multikinase inhibitors (sorafenib [S]: vascular endothelial growth factor receptor [VEGF-R], platelet derived growth factor receptor, RET; vandetanib [V]: VEGF-R, endothelial growth factor receptor [EGF-R]; and MLN8054 [M]: Aurora kinases [AK]). Antiproliferative, antiangiogenic, and proapoptotic effects were evaluated.

RESULTS

Treatment of successfully xenotransplanted fresh ATC tumor tissue by multikinase inhibitors and aurora kinase inhibitor reduced the tumor volume up to 61% depending on the drug and time of application (3 wk of treatment: 46% [M], 34% [V], 30% [S]; 5 wk of treatment: 61% [S]). Tumor cell proliferation (BrdU) was reduced between 34% and 58% [S] and [V]. Reduction of tumor vascularity was between 67% [V] and 33% [S] and was accompanied by decreased EGF-R/VEGF-R2 receptor activity [V/V,S]. Tumor cell apoptosis (caspase 3 activity) increased up to 2.4-fold [S].

CONCLUSIONS

Successful in vivo evaluation of novel drugs in xenotransplanted fresh tumor tissue allows in-time (while patient receives standard treatment) prospective analysis for possible additional clinical application. However, technical specifications have to be taken into account to obtain stable in vivo tumor growth. Based on the individual results, a tailored clinical drug application seems possible.

Design, synthesis and structure-activity relationships of some novel, highly potent anti-invasive (E)- and (Z)-stilbenes

In our ongoing exploration of the structure-activity landscape of anti-invasive chalcones, we have prepared and evaluated a number of structurally related (E)- and (Z)-stilbenes. These molecules exhibited an extraordinary high in vitro potency in the chick heart invasion assay, being active up to 10nmolL(-1), a concentration level a 100-fold lower than the lowest effective doses that have been reported for natural analogues. Furthermore, they possess an interesting pharmacological profile in silico.

Therapeutic strategies in the management of patients with metastatic anaplastic thyroid cancer: review of the current literature

PURPOSE OF REVIEW

Anaplastic thyroid cancer (ATC) is a rare and deadly malignancy. There is a need to speed up and support clinical research. This review article focuses on the new molecules that have been developed for the treatment of this aggressive tumor.

RECENT FINDINGS

Improvement in the knowledge of pathogenesis and genetics of ATC led to the development of a variety of new molecules that may be used to treat this disease. In summary, these molecules are proteasome inhibitors, Aurora kinase inhibitors, vascular targeting agents, and gene therapies. All these molecules demonstrated a potentially therapeutic activity in metastatic ATC. To date, the largest prospective randomized multicenter, open-label, trial was conducted with combretastatin-A4.

SUMMARY

More efficient drugs need to be developed through multinational efforts.

Efatutazone, an oral PPAR-γ agonist, in combination with paclitaxel in anaplastic thyroid cancer: results of a multicenter phase 1 trial

PURPOSE

A phase 1 study was initiated to determine the safety, potential effectiveness, and maximal tolerated dose and recommended phase 2 dose of efatutazone and paclitaxel in anaplastic thyroid cancer.

EXPERIMENTAL DESIGN

Patients received efatutazone (0.15, 0.3, or 0.5 mg) orally twice daily and then paclitaxel every 3 weeks. Patient tolerance and outcomes were assessed, as were serum efatutazone pharmacokinetics.

RESULTS

Ten of 15 patients were women. Median age was 59 years. Seven patients received 0.15 mg of efatutazone, 6 patients received 0.3 mg, and 2 patients received 0.5 mg. One patient receiving 0.3 mg of efatutazone had a partial response from day 69 to day 175; 7 patients attained stable disease. Median times to progression were 48 and 68 days in patients receiving 0.15 mg of efatutazone and 0.3 mg of efatutazone, respectively; corresponding median survival was 98 vs 138 days. The median peak efatutazone blood level was 8.6 ng/mL for 0.15-mg dosing vs 22.0 ng/mL for 0.3-mg twice daily dosing. Ten patients had grade 3 or greater adverse events (Common Terminology Criteria for Adverse Events), with 2 of these (anemia and edema) related to efatutazone. Thirteen events of edema were reported in 8 patients, with 2 of grade 3 or greater. Eight patients had ≥1 serious adverse event, with 1 of these (anemia) attributed to efatutazone and 1 (anaphylactic reaction) related to paclitaxel. The maximal tolerated dose was not achieved. Angiopoietin-like 4 was induced by efatutazone in tissue biopsy samples of 2 patients.

CONCLUSIONS

Efatutazone and paclitaxel in combination were safe and tolerated and had biologic activity.

New targeted therapies and other advances in the management of anaplastic thyroid cancer

PURPOSE OF REVIEW

Anaplastic thyroid cancer is the most aggressive solid tumor known to humans. Even when found in a localized form, the prognosis is grave. For metastatic disease, there has been little effect on survival using traditional chemotherapy.

RECENT FINDINGS

Over a five-decade interval, there has been little progress in the treatment of this malignancy. However, targeted agents represent a new mode of treatment, and some studies have shown encouraging preclinical results. Combretastatin has shown activity in phase 1 and phase II trials; although the registration phase III study failed to meet its accrual goals, it did appear to show some benefit, especially in younger patients.

SUMMARY

Combinations of this compound and other targeted agents may prove to be a breakthrough in an otherwise untreatable cancer.

Phase II trial of sorafenib in patients with advanced anaplastic carcinoma of the thyroid

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but highly aggressive malignancy with a median survival of 3-5 months. The BRAF oncogene is mutated to its active form in up to 24% of ATC cases. Sorafenib is a tyrosine kinase inhibitor that acts on the RAF-1 serine/threonine kinase. In preclinical mouse models, sorafenib inhibits the growth of ATC xenografts and improves survival. No study of sorafenib in ATC has been conducted. We conducted a multi-institutional phase II trial of sorafenib in patients with ATC who had failed up to two previous therapies.

METHODS

The primary endpoint of the trial was the Response Evaluation Criteria In Solid Tumors (RECIST)-defined imaging response rate. Twenty patients with ATC were treated with sorafenib 400 mg twice daily.

RESULTS

Two of the 20 patients had a partial response (10%) and an additional 5 of 20 (25%) had stable disease. The duration of response in the two responders was 10 and 27 months, respectively. For the patients with stable disease, the median duration was 4 months (range 3-11 months). The overall median progression-free survival was 1.9 months with a median and a 1-year survival of 3.9 months and 20%, respectively. Toxicity was manageable and as previously described for sorafenib, including hypertension and skin rash.

CONCLUSION

Sorafenib has activity in ATC, but at a low frequency and similar to our previous experience with fosbretabulin. One patient with a response had previously progressed on fosbretabulin. Toxicities were both predictable and manageable.

Aggressive surgical resection of anaplastic thyroid carcinoma may provide long-term survival in selected patients

OBJECTIVE

In this study, we present our experience with aggressive surgical treatment in selected patients with anaplastic thyroid cancer with extrathyroidal extension.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary care referral center.

SUBJECTS AND METHODS

Retrospective chart review of all patients with anaplastic thyroid cancer surgically treated by the senior author from January 1998 to July 2012.

RESULTS

A total of 38 cases of anaplastic thyroid cancer were treated (21 male and 17 female). The mean age was 64.5 years. Twenty-two patients were considered surgically unresectable (18 had distant metastases and 4 had extrathyroidal extension of cancer lateral to carotid arteries) and underwent biopsy with or without tracheostomy. The remaining 16 patients underwent surgical resection with curative intent. Fourteen of these patients underwent postoperative radiation therapy. None of these 16 patients developed local recurrence. Six developed distant metastasis at an average follow-up of 3.2 months, 1 died of an unrelated myocardial infarction at 3 months, 2 were lost to follow-up, and 7 remain disease free with an average follow-up of 4.8 years (range, 9 months to 8 years). Of those patients who underwent complete surgical resection followed by postoperative radiation, 7 of 14 (50%) are still alive, with a mean follow-up of 4.8 years.

CONCLUSION

Selected patients with anaplastic thyroid cancer with extrathyroidal extension (stage IVB) who show no distant metastases by computed tomography or positron emission tomography scans and who do not have tumor extending lateral to the carotid arteries are candidates for complete surgical resection.

Novel cis-restricted β-lactam combretastatin A-4 analogues display anti-vascular and anti-metastatic properties in vitro

Combretastatin A-4 (CA-4) is a naturally occurring microtubular-destabilising agent that possesses potent anti-tumour and anti-vascular properties both in vitro and in vivo. Clinical trials to date indicate that its water-soluble prodrug, combretastatin A-4 phosphate (CA-4P), is well tolerated at therapeutically useful doses. However, the stilbenoid structure of CA-4, consisting of two phenyl rings linked by an ethylene bridge, renders the compound readily susceptible to isomerisation from its biologically active cis-conformation to its more thermodynamically stable but inactive trans-isomer. To circumvent this problem, we synthesised a series of cis-restricted CA-4 analogues. Replacement of the ethylene bridge with a 1,4-diaryl-2-azetidinone (β-lactam) ring provided a rigid scaffold thus preventing cis-trans isomerisation. We previously documented that these tubulin-depolymerising β-lactam compounds potently induced cell cycle arrest and apoptosis in a variety of cancerous cell lines (including those displaying multidrug resistance) and ex vivo patient samples, whilst exerting only minimal toxicity to normal cells. The purpose of this study was to elucidate the effect of the β-lactam compounds on both tumour vascularisation and tumour cell migration, two critical elements that occur during the growth and metastatic progression of tumours. We established that two representative β-lactam compounds, CA-104 and CA-432, exerted both anti-endothelial effects [G2/M arrest and apoptosis of primary human umbilical vein endothelial cells (HUVECs)] and anti-angiogenic effects [inhibition of HUVEC migration and differentiation and reduced vascular endothelial growth factor (VEGF) release from MDA-MB-231 breast adenocarcinoma cells]. In addition, we established that lead analogue, CA-432, abrogated the migration of MDA-MB-231 cells indicating an anti-metastatic function for these compounds. In summary, our results to date collectively indicate that these cis-restricted β-lactam CA-4 analogues may prove to be useful alternatives to CA-4 in the treatment of cancer but with the added advantage of improved stability of the cis-isomer.

Combined inhibition of cellular pathways as a future therapeutic option in fatal anaplastic thyroid cancer

Conventional treatment by surgery, radioiodine, and thyroxin-suppressive therapy often fails to cure anaplastic thyroid cancer (ATC). Therefore several attempts have been made to evaluate new therapy options by use of "small molecule inhibitors". ATC was shown to respond to monotherapeutic proteasome and Aurora kinase inhibition in vitro as well as in xenotransplanted tumor cells. Aim of this study was to evaluate the effect of combined treatment targeting the ubiquitin-proteasome system by bortezomib and Aurora kinases by use of MLN8054. Three ATC cell lines (Hth74, C643, and Kat4.1) were used. The antiproliferative effect of combined treatment with bortezomib and MLN8054 was assessed by MTT-assay and cell cycle analysis (FACS). Proapoptotic effects were evaluated by measurement of Caspase-3 activity, and effects on VEGF secretion were analyzed by ELISA. Compared to mono-application combined treatment with bortezomib and MLN8054 resulted in a further decrease of cell density, whereas antagonizing effects were found regarding cell cycle progression. Caspase-3 activity was increased up to 2.7- and 14-fold by mono-application of MLN8054 and bortezomib, respectively. When the two drugs were used in combination, a further enhancement of Caspase-3 activity was achieved, depending on the cell line. VEGF secretion was decreased following bortezomib treatment and remained unchanged by MLN8054. Only in C643 cells, the bortezomib-induced down-regulation was enhanced when MLN8054 was applied simultaneously. In conclusion, our data demonstrate that targeting the proteasome and Aurora kinases simultaneously results in additional antitumoral effects in vitro, especially regarding cell growth and induction of apoptosis. The efficacy of this therapeutic approach remains to be revised by in vivo and clinical application.

American Thyroid Association guidelines for management of patients with anaplastic thyroid cancer

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but highly lethal form of thyroid cancer. Rapid evaluation and establishment of treatment goals are imperative for optimum patient management and require a multidisciplinary team approach. Here we present guidelines for the management of ATC. The development of these guidelines was supported by the American Thyroid Association (ATA), which requested the authors, members the ATA Taskforce for ATC, to independently develop guidelines for ATC.

METHODS

Relevant literature was reviewed, including serial PubMed searches supplemented with additional articles. The quality and strength of recommendations were adapted from the Clinical Guidelines Committee of the American College of Physicians, which in turn was developed by the Grading of Recommendations Assessment, Development and Evaluation workshop.

RESULTS

The guidelines include the diagnosis, initial evaluation, establishment of treatment goals, approaches to locoregional disease (surgery, radiotherapy, systemic therapy, supportive care during active therapy), approaches to advanced/metastatic disease, palliative care options, surveillance and long-term monitoring, and ethical issues including end of life. The guidelines include 65 recommendations.

CONCLUSIONS

These are the first comprehensive guidelines for ATC and provide recommendations for management of this extremely aggressive malignancy. Patients with stage IVA/IVB resectable disease have the best prognosis, particularly if a multimodal approach (surgery, radiation, systemic therapy) is used, and some stage IVB unresectable patients may respond to aggressive therapy. Patients with stage IVC disease should be considered for a clinical trial or hospice/palliative care, depending upon their preference.

A multiinstitutional phase 2 trial of pazopanib monotherapy in advanced anaplastic thyroid cancer

CONTEXT/OBJECTIVES

Pazopanib, an inhibitor of kinases including vascular endothelial growth factor receptor, demonstrated impressive activity in progressive metastatic differentiated thyroid cancer, prompting its evaluation in anaplastic thyroid cancer (ATC).

DESIGN/SETTING/PATIENTS/INTERVENTIONS/OUTCOME MEASURES

Preclinical studies, followed by a multicenter single arm phase 2 trial of continuously administered 800 mg pazopanib daily by mouth (designed to provide 90% chance of detecting a response rate of >20% at the 0.10 significance level when the true response rate is >5%), were undertaken. The primary trial end point was Response Evaluation Criteria in Solid Tumors (RECIST) response.

RESULTS

Pazopanib displayed activity in the KTC2 ATC xenograft model, prompting clinical evaluation. Sixteen trial patients were enrolled; 15 were treated: 66.7% were female, median age was 66 yr (range 45-77 yr), and 11 of 15 had progressed through prior systemic therapy. Enrollment was halted, triggered by a stopping rule requiring more than one confirmed RECIST response among the first 14 of 33 potential patients. Four patients required one to two dose reductions; severe toxicities (National Cancer Institute Common Toxicity Criteria-Adverse Events version 3.0 grades >3) were hypertension (13%) and pharyngolaryngeal pain (13%). Treatment was discontinued because of the following: disease progression (12 patients), death due to a possibly treatment-related tumor hemorrhage (one patient), and intolerability (radiation recall tracheitis and uncontrolled hypertension, one patient each). Although transient disease regression was observed in several patients, there were no confirmed RECIST responses. Median time to progression was 62 d; median survival time was 111 d. Two patients are alive with disease 9.9 and 35 months after the registration; 13 died of disease.

CONCLUSIONS

Despite preclinical in vivo activity in ATC, pazopanib has minimal single-agent clinical activity in advanced ATC.

Approach to the patient with anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma is the least common but most lethal of thyroid cancers. All patients are classified as stage IV, with the primary lesion restricted to the thyroid gland in stage IVA; locoregional lymph nodes may exist in IVA/IVB; and IVC disease is defined by distant metastases. Prognosis is highly dependent on disease extent at presentation, and staging and establishing a plan of care must be accomplished quickly. Although almost all studies are biased due to their retrospective nature, the most important factors associated with longer survival are completeness of surgical resection (achievable in only a minority of patients) and high-dose (>40 Gy) external beam radiotherapy (preferably intensity modulated radiation therapy). Recent reports suggest that a multimodal approach (surgery, radiation, and chemotherapy) is beneficial. Given the high lethality even with apparent local disease, combination systemic therapy (cytotoxics and/or targeted agents) may improve outcomes in stage IVA/IVB patients. Newer, more effective drug combinations are urgently needed for IVC patients who want aggressive therapy. A candid discussion of the prognosis and management options, including palliative care/hospice, should be held with the patient and caregiver as soon as possible after diagnosis to clarify the patient's preference and expectations. Prospective multicenter clinical trials, incorporating molecular analyses of tumors, are required if we are to improve survival in anaplastic thyroid carcinoma.

Phase I, pharmacokinetic and pharmacodynamic evaluation of CYT997, an orally-bioavailable cytotoxic and vascular-disrupting agent

PURPOSE

CYT997 is a novel microtubule inhibitor and vascular disrupting agent. This phase I trial examined the safety, tolerability, pharmacokinetics and vascular-disrupting effects of orally-administered CYT997.

EXPERIMENTAL DESIGN

We performed a phase I accelerated dose-escalation study of CYT997 given orally once every 2 to 3 weeks in patients with advanced solid tumours. Vascular disruption was assessed by measurement of plasma von Willebrand factor (vWF) levels and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

RESULTS

A total of 56 doses were administered to 21 patients over 8 dose levels (15-164 mg/m(2)). Grade 3 fatigue and grade 3 hypoxia were dose limiting. Oral bioavailability was observed with approximate linear pharmacokinetics over the 11-fold dose range. At doses of 84 mg/m(2) and above, plasma vWF levels increased above baseline and DCE-MRI scans showed reductions in tumour K(trans) in some patients.

CONCLUSIONS

CYT997 is orally bioavailable. The 118 mg/m(2) dose level should be used to guide dosing in future studies.

Antineoplastic agents. 548. Synthesis of iodo- and diiodocombstatin phosphate prodrugs

Toward the objective of designing a structurally modified analogue of the combretastatin A-4 phosphate prodrug (1b) with the potential for increased specificity toward thyroid carcinoma, synthesis of a series of iodocombstatin phosphate (11a-h) and diiodocombstatin phosphate prodrugs (12a-h) has been accomplished. The diiodo series was obtained via 8a and 9c from condensation of 4 and 6, and the iodo sequence involved a parallel pathway. Both series of iodocombstatins were found to display significant to powerful inhibition of the growth of a panel of human cancer cell lines and of the murine P388 lymphocytic leukemia cell line. Of the diiodo series, 12a was also found to markedly inhibit growth of pediatric neuroblastoma, and monoiodocombstatin 9a strongly inhibited HUVEC growth. Overall, the strongest activity was found against the breast, CNS, leukemia, lung, and prostate cancer cell lines and the least activity against the pancreas and colon lines. Parallel biological investigations of tubulin interaction, antiangiogenesis, and antimicrobial effects were also conducted.

An Amino-Benzosuberene Analogue That Inhibits Tubulin Assembly and Demonstrates Remarkable Cytotoxicity

The recent discovery of a small-molecule benzosuberene-based phenol that demonstrates remarkable picomolar cytotoxicity against selected human cancer cell lines and strongly inhibits tubulin polymerization (1-2 µM) inspired the design and synthesis of a variety of new, structurally diverse benzosuberene derivatives. An efficient synthetic route to functionalized benzosuberenes was developed. This methodology utilized a Wittig reaction, followed by a selective alkene reduction and ring-closing cyclization to form the core benzosuberone structure. This synthetic route facilitated the preparation of a 6-nitro-1-(3',4',5'-trimethoxyphenyl) benzosuberene derivative and its corresponding 6-amino analogue in good yield. The 6-amino analogue was a strong inhibitor of tubulin polymerization (1.2 µM), demonstrated enhanced cytotoxicity against the human cancer cell lines examined (GI₅₀ = 33 pM against SK-OV-3 ovarian cancer, for example), and exhibited a concentration dependent disruption of a pre-established capillary-like network of tubules formed from human umbilical vein endothelial cells.