Thalidomide may impede cell migration in primates by down-regulating integrin beta-chains: potential therapeutic utility in solid malignancies, proliferative retinopathy, inflammatory disorders, neointimal hyperplasia, and osteoporosis

Identification of a variant in NLRP3 gene in a patient with Muckle-Wells syndrome: a case report and review of literature

BACKGROUND

Cryopyrin-associated periodic syndrome (CAPS), a rare genetic autoimmune disease, is composed of familial cold autoinflammatory syndrome (FCAs), Muckle-Wells syndrome (MWS), and neonatal onset multisystem inflammatory disease (NOMID). MWS is caused by dominantly inherited or de novo gain-of-function mutations in the NOD-like receptor 3 (NLRP3) gene. At present, there is no report about the variation of R262W in China.

CASE PRESENTATION

We reported a 3-year-old Chinese boy who had recurrent fever without obvious inducement, bilateral conjunctival congestion, and urticarial-like rash. Laboratory examination showed elevation in leukocyte count, neutrophil count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) and serum amyloid protein (SAA) levels. Whole exome sequencing identified a missense variation c.784-786delinsTGG (p.R262W) in the coding region of the NLRP3 gene.

CONCLUSION

A classical variant of the NLRP3 gene in a patient with MWS was first reported in China.

Antiangiogenic therapy for primitive neuroectodermal tumor with thalidomide: A case report and review of literature

RATIONALE

Peripheral primitive neuroectodermal tumor (PNET) is a kind of small round cell tumor derived from primitive neuroectodermal tumor.

PATIENT CONCERNS

PNET is a highly malignant tumor that is subordinated to Ewing sarcoma. It occurs predominantly in soft tissue and bone and rarely in the bronchi and lung. Traditional surgery, radiotherapy, and chemotherapy are used for the treatment of PNET, but are usually ineffective.

DIAGNOSES

There was a rare case of a 17 year-old man diagnoses with primary pulmonary PNET.

INTERVENTIONS

The patient was treated by the remedy treatment with thalidomide after the poor effect of conventional radiotherapy and chemotherapy.

OUTCOMES

The patient survived without disease progression for 15 months and was in stable condition.

LESSONS

Thalidomide provides a choice for maintenance therapy in PNET.

Glioblastoma multiforme: Pathogenesis and treatment

Each year, about 5-6 cases out of 100,000 people are diagnosed with primary malignant brain tumors, of which about 80% are malignant gliomas (MGs). Glioblastoma multiforme (GBM) accounts for more than half of MG cases. They are associated with high morbidity and mortality. Despite current multimodality treatment efforts including maximal surgical resection if feasible, followed by a combination of radiotherapy and/or chemotherapy, the median survival is short: only about 15months. A deeper understanding of the pathogenesis of these tumors has presented opportunities for newer therapies to evolve and an expectation of better control of this disease. Lately, efforts have been made to investigate tumor resistance, which results from complex alternate signaling pathways, the existence of glioma stem-cells, the influence of the blood-brain barrier as well as the expression of 0(6)-methylguanine-DNA methyltransferase. In this paper, we review up-to-date information on MGs treatment including current approaches, novel drug-delivering strategies, molecular targeted agents and immunomodulative treatments, and discuss future treatment perspectives.

Mechanism of immunomodulatory drugs' action in the treatment of multiple myeloma

Although immunomodulatory drugs (IMiDs), such as thalidomide, lenalidomide, and pomalidomide, are widely used in the treatment of multiple myeloma (MM), the molecular mechanism of IMiDs' action is largely unknown. In this review, we will summarize recent advances in the application of IMiDs in MM cancer treatment as well as their effects on immunomodulatory activities, anti-angiogenic activities, intervention of cell surface adhesion molecules between myeloma cells and bone marrow stromal cells, anti-inflammatory activities, anti-proliferation, pro-apoptotic effects, cell cycle arrest, and inhibition of cell migration and metastasis. In addition, the potential IMiDs' target protein, IMiDs' target protein's functional role, and the potential molecular mechanisms of IMiDs resistance will be discussed. We wish, by presentation of our naive discussion, that this review article will facilitate further investigation in these fields.

Thalidomide in advanced hepatocellular carcinoma as antiangiogenic treatment approach: a phase I/II trial

BACKGROUND

The high vascularity of hepatocellular carcinoma (HCC) seems to be a potential therapeutic target. We evaluated the efficacy, toxicity, and histologic response to thalidomide in advanced HCC in a single center phase I/II pilot trial.

METHODS

Between September 2000 and August 2004 patients with HCC uneligible for any established therapy were enrolled in the study. The initial thalidomide dosage of 100 mg/day was escalated in 100 mg steps weekly up to 300 mg/day based on tolerability. Discontinuation and dose reduction were based on toxicity. Tumor biopsies were scheduled to assess tumor microvessel density and serum levels of angiogenic factors, vascular endothelial growth factor, basic fibroblast growth factor, and endostatin were determined.

RESULTS

Twenty-eight patients with histologically proven HCC were entered into this study. The median maximum-tolerated dose of thalidomide was 300 mg/day. Most common toxicities were fatigue (75%), dizziness (64%), nausea (43%), and constipation (39%). Two patients had stable disease for 2.6 and 5.4 months, the remaining 26 patients had disease progression. The median overall survival was 5.1 months. Well preserved liver function was associated with longer overall survival on univariate analysis (P=0.0279). The serum concentrations of vascular endothelial growth factor and endostatin increased significantly (P=0.039 and P=0.024, respectively) after 3 months of thalidomide treatment. No clear differences were observed between the serum basic fibroblast growth factor concentrations at study entry and after 3 months (P=0.983). Microvessel density did not decrease significantly during thalidomide therapy (P=0.109).

CONCLUSION

Thalidomide is moderately tolerated and minimally effective in large HCC.

Present trend in the primary treatment of aggressive malignant glioma: glioblastoma multiforme

The standard treatment for glioblastoma multiforme is surgery, radiation, and chemotherapy. Yet this aggressive therapy has only a modest effect on survival with most patients surviving less than 1 year after diagnosis. This poor prognosis has lead scientists to seek alternative molecular approaches for the treatment of glioblastoma multiforme. Among these, gene therapy, vaccine therapy, and immunotherapy are all approaches that are currently being investigated. While these molecular approaches may not herald an immediate change in the prognosis of these aggressive tumors, combining them with existing approaches may bring some progress in the standard of care. This paper reviews current treatments and several newer therapies in preclinical and early clinical studies.

From molecular biology to targeted therapies for hepatocellular carcinoma: the future is now

Hepatocellular carcinoma (HCC) is characterized as a highly chemoresistant cancer with no effective systemic therapy. Despite surgical or locoregional therapies, prognosis remains poor because of high tumor recurrence or tumor progression, and currently there are no well-established effective adjuvant therapies. The molecular biology of carcinogenesis and tumor progression of HCC has been increasingly understood with intense research in recent years. Several important intracellular signaling pathways such as the Ras/Raf/Mek/Erk pathway and PI3k/Akt/mTOR pathway have been recognized, and the role of several growth factors and angiogenic factors such as EGF and VEGF has been confirmed. Effective agents targeting these molecular abnormalities have been developed and widely tested in preclinical studies of HCC cell lines or xenograft models. Several agents have entered clinical trials in HCC patients, and recent data indicated that a multikinase inhibitor targeting Ras kinase and VEGFR-2, sorafenib, is effective in prolonging survival of patients with advanced HCC. The management of advanced HCC is entering the era of molecular targeting therapy, which is of particular significance for HCC in view of the lack of existing effective systemic therapy for this cancer.

Phase II trial of thalidomide for advanced and recurrent gynecologic sarcoma: A brief communication from the New York Phase II consortium

OBJECTIVE

To define the efficacy of thalidomide on the overall survival of patients with metastatic recurrent gynecologic sarcomas.

PATIENTS AND METHODS

All patients with sarcoma or carcinosarcoma of gynecologic origin and documented recurrence or persistence of disease after appropriate surgery, radiation therapy and/or chemotherapy were recruited to the study. All patients were ambulatory and had measurable disease that could be documented on CT scan. Patients were started on 200 mg/day of thalidomide orally every night and escalated by 100-200 mg every 7 to 14 days. The length of the treatment was separated into 2 cycles with the first 84 days defined as the first cycle and the next 56 days as the second cycle. Common Toxicity Criteria were used to record toxicities. Because thalidomide was postulated to induce cytostasis, the end-points were progression-free and overall survival in this mixed group of patients.

RESULTS

Seventeen patients were enrolled. The drug was not well tolerated because of constipation, fatigue, worsening performance status, drowsiness and sleepiness. The total dosage of medication given to each patient ranged from 3200 mg to 40,500 mg. The maximum dosage reached in each patient ranged from 300 mg to 750 mg, with the total time of treatment ranging from 13 to 99 days. All patients had progression of disease with a median progression-free survival time of 1.84 months (CI 1.54-2.79 months) and a median overall survival of 6.64 months.

DISCUSSION

Thalidomide has no activity in patients with advanced or recurrent gynecologic sarcomas and was not well-tolerated. The overall survival was <7 months. The progression-free survival was <3 months, and, since the therapy was not tolerated well, we unanimously decided to close the study at this point. Despite the poor result, we still believe in the strategy of anti-angiogenesis and will continue to pursue other potential treatment options using the same concept.

Thalidomide and analogues: current proposed mechanisms and therapeutic usage

Microvessel density is a prognostic factor for many cancers, including prostate. For this reason, several studies and therapeutic approaches that target the tumor microvasculature have been attempted. Thalidomide has long been recognized as an antiangiogenic molecule. Recently, this drug has regained favor as an anticancer agent and is in clinical trial for multiple myeloma and prostate cancer, among others. This article will briefly review the proposed mechanisms of action for thalidomide, discuss why these activities are of therapeutic value in diseases currently undergoing clinical trials, and summarize the current status of clinical trials for prostate cancer. The focus will be predominantly on the relationship of thalidomide to angiogenesis, as well as on the future and potential value of thalidomide-inspired structural derivatives.

Phase II trial and pharmacokinetic study of thalidomide in patients with metastatic colorectal cancer

INTRODUCTION

This study was designed to estimate the percentage of objective tumor responses, toxicity profile, and obtain additional information about the plasma pharmacokinetics of thalidomide in patients with refractory and progressing metastatic colorectal cancer.

STUDY DESIGN

This phase II clinical trial was conducted according to the two-stage Simon method with the inclusion of consecutive patients. The study protocol was approved by the Institutional Review Board (IRB) of the Academic Hospital (HCPA) of the Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.

PATIENTS AND METHODS

Seventeen patients with previously treated, refractory progressive metastatic colorectal cancer were eligible. Six patients had prior radiotherapy. The patients had a median of one previous chemotherapy regimen. Patients were initially treated with 200 mg/day of thalidomide with an increase in dose by 200 mg/day every 2 weeks until a final daily dose of 800 mg/day was achieved. Patients were evaluated every 8 weeks for response by radiographic criteria. Plasma pharmacokinetics studies were performed in four patients at 200 mg level and in one patient at 600 mg during the first 24 h.

MAIN OUTCOME MEASURES AND RESULTS

A total of 17 patients were accrued, all of them being evaluable for toxicity and 14 for response. Thalidomide was well tolerated, with constipation, somnolence, dizziness, and dry mouth being the major toxicities. There were no objective response or stable disease. The median survival was 3.6 months. Single-agent thalidomide is a generally well-tolerated drug that showed no antitumor activity in patients with advanced pretreated metastatic colorectal cancer. Although thalidomide did not show antitumor activity in this patient population, future studies of this agent in patients at initial stages of the disease (when its antiangiogenic properties may be more relevant to disease progression) could be considered.

Review Article. New treatments in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of legal blindness in individuals 50 years and older in the developed world. Choroidal neovascularization (CNV) in exudative AMD is responsible for the majority of severe vision loss. Until recently, laser photocoagulation was the only well-established and widely accepted treatment for CNV. However, it is beneficial only for a small subset of patients, has a high rate of CNV persistence and recurrence and results in iatrogenic, collateral damage to the overlying retina. These issues make it difficult to recommend in the case of subfoveal lesions. Consequently, numerous experimental therapeutic interventions are under investigation with the common objective of destroying the CNV but leaving the foveal neurosensory retina intact. Treatment modalities can be grouped into five major categories: photodynamic therapy; radiotherapy; transpupillary thermotherapy; anti-angiogenic and angiostatic agents; and surgical intervention. The present review aims to explain the rationale behind these new treatments, analyse the evidence for their safety and efficacy, determine their stage of development and indicate in which patients they are potentially useful.

Dermatologic and nondermatologic uses of thalidomide

OBJECTIVE

To review published data on thalidomide, with emphasis on current knowledge about mechanism of action, new and/or potential dermatologic and nondermatologic therapeutic applications, well-known and emerging adverse effects, and current indications for its safe use.

DATA SOURCES

Review articles, in vitro research studies, references from retrieved articles, case reports, and clinical trials were identified from a computerized literature search using MEDLINE and OVID (1966-January 2003) and on the Cochrane Clinical Trials Register (January 2003). Information available from meetings' abstract books, Internet, or pharmaceutical companies was also considered.

STUDY SELECTION AND DATA EXTRACTION

All articles identified as relevant, including those from non-English literature, were considered in an attempt to provide to the reader both the theoretical basis and practical guidelines for thalidomide pharmacotherapy.

DATA SYNTHESIS

Thalidomide has hypnosedative, antiangiogenic, antiinflammatory, and immunomodulatory properties. Moreover, it has been shown to selectively inhibit the production of tumor necrosis factor-alpha and reduce the expression of various integrin receptors on the membrane of leukocytes and other cell types in a dose-dependent fashion. Controlled trials demonstrated the efficacy of thalidomide in a number of diseases, including erythema nodosum leprosum, lupus erythematosus, aphthosis, graft-versus-host disease, prurigo nodularis, and actinic prurigo. Single case reports or studies in small series have also suggested a possible role for thalidomide in numerous other dermatologic and nondermatologic disorders. Possibly severe and sometimes irreversible risks related to the clinical use of thalidomide include teratogenicity and neurotoxicity.

CONCLUSIONS

Although teratogenicity and neurotoxicity are significant adverse effects requiring cautious use, thalidomide is an effective therapeutic modality in a variety of difficult-to-treat disorders and, providing careful selection of patients, should offer an acceptable risk-to-benefit ratio.

A wholly nutritional 'multifocal angiostatic therapy' for control of disseminated cancer

A great deal of effort is now being devoted to the development of new drugs that hopefully will control the spread of inoperable cancer by safely inhibiting tumor-evoked angiogenesis. However, there is growing evidence that certain practical nutritional measures have the potential to slow tumor angiogenesis, and it is reasonable to anticipate that, by combining several measures that work in distinct but complementary ways to impede the angiogenic process, a clinically useful 'multifocal angiostatic therapy' (MAT) might be devised. Several measures which might reasonably be included in such a protocol are discussed below, and include: a low-fat, low-glycemic index vegan diet, which may down-regulate the systemic IGF-I activity that supports angiogenesis; supplemental omega-3-rich fish oil, which has been shown to inhibit endothelial expression of Flk-1, a functionally crucial receptor for VEGF, and also can suppress tumor production of pro-angiogenic eicosanoids; high-dose selenium, which has recently been shown to inhibit tumor production of VEGF; green tea polyphenols, which can suppress endothelial responsiveness to both VEGF and fibroblast growth factor; and high-dose glycine, whose recently reported angiostatic activity may reflect inhibition of endothelial cell mitosis, possibly mediated by activation of glycine-gated chloride channels. In light of evidence that tumor-evoked angiogenesis has a high requirement for copper, copper depletion may have exceptional potential as an angiostatic measure, and is most efficiently achieved with the copper-chelating drug tetrathiomolybdate. If logistical difficulties make it difficult to acquire this experimental drug, high-dose zinc supplementation can achieve a slower depletion of the body's copper pool, and in any case can be used as maintenance therapy to maintain an adequate level of copper depletion. A provisional protocol is offered for a nutritionally based MAT entailing a vegan diet and supplemental intakes of fish oil, selenium, green tea polyphenols, glycine, and zinc. Inasmuch as cox-2 is overexpressed in many cancers, and cAMP can boost tumor production of various angiogenic factors as well as autogenous growth factors, adjunctive use of cox-2-specific NSAIDS may be warranted in some cases.

Effects of thalidomide, cytochrome P-450 and TNF-alpha on angiogenesis in a three-dimensional collagen gel-culture

The anti-angiogenic effects of thalidomide were examined in mouse aortae grown in a three-dimensional collagen gel-culture. In our in vitro model, (+/-)-thalidomide and (-)-thalidomide exhibited no anti-angiogenic effects. On the other hand, when the culture was treated with thalidomide plus cytochrome P-450, both types of thalidomides significantly inhibited angiogenesis. Co-administration of 100 microg/ml thalidomide plus 200 microg/ml cytochrome P-450 inhibited angiogenesis more strongly than thalidomide plus cytochrome P-450 at other concentrations (10 microg/ml + 200 microg/ml and 100 microg/ml + 20 microg/ml). To study the relation between the anti-angiogenic effect and TNF-alpha, we also evaluated the concentration of TNF-alpha in the culture medium. We found that the concentration of TNF-alpha was correlated to the strength of the anti-angiogenic effect. The inhibition of angiogenesis by thalidomide and cytochrome P-450 takes place through a suppression of TNF-alpha and involves the metabolism of the thalidomide.

Renal cell carcinoma may adapt to and overcome anti-angiogenic intervention with thalidomide

OBJECTIVE

To report on the failure of thalidomide to inhibit tumour growth in an animal model of human renal cell carcinoma (RCC).

MATERIALS AND METHODS

An orthotopic xenograft model of human RCC was used in which tumour cells were implanted in the left kidney of male 'severe combined immunodeficient' mice. Thalidomide was administered by intraperitoneal injection and after 34 days the mice were killed. The extent of tumour growth was compared in treated and untreated mice. Total RNA was extracted from both tumour-affected and contralateral kidneys, and analysed by reverse transcription-polymerase chain reaction for various genes implicated in angiogenesis and metastasis in RCC.

RESULTS

Thalidomide failed to inhibit the growth of xenograft tumours. The expression of angiogenic genes, e.g. vascular endothelial growth factor and fibroblast growth factor type 2 (FGF-2) within normal and tumour-affected kidney tissue was not reduced by thalidomide. Intratumoral transcription of beta3-integrin, a critical component of angiogenesis, was significantly increased in response to thalidomide treatment (P < 0.01). There was also a trend to increased expression of FGF-2 and tumour necrosis factor-alpha in thalidomide-treated tumours.

CONCLUSIONS

These findings suggest that RCC is capable of adapting to the inhibitory effects of thalidomide. The current uncertainty surrounding the action of thalidomide in vivo warrants caution about its use in humans. Further studies of thalidomide should be carried out in animal models, particularly to establish its safety and effectiveness as part of a combined therapeutic strategy.

Theoretical basis for the activity of thalidomide

The revival of thalidomide began shortly after the drug was withdrawn from the market because of its teratogenic properties. Therapeutic effects of thalidomide were found accidentally in leprosy patients with erythema nodosum leprosum (ENL). Subsequent research widened the understanding of the activity of thalidomide, and with improved methodology and the augmented background knowledge of immunology it was possible to interpret the properties of thalidomide more coherently. Effects on tumour necrosis factor-alpha (TNFalpha) release play an important role in the ability of thalidomide to affect the immune system. Alteration of synthesis and release of cytokines such as interleukin (IL)-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12 and interferon-gamma is involved in the complex mechanisms of thalidomide. Thalidomide targets leucocytes, endothelial cells and keratinocytes, affecting them in a different manner and at different cellular levels. Changes in the density of adhesion molecules alter leucocyte extravasation and the inflammatory response in the tissue involved. Several mechanisms for the teratogenic action of thalidomide are currently under review, but this mode of action of the drug still remains unclear and we review evidence-based hypotheses for the teratogenicity of thalidomide. Thalidomide shows significant clinical impact in several diseases such as ENL in lepromatous leprosy, chronic graft-versus-host disease, systemic lupus erythematosus, sarcoidosis, aphthous lesions in HIV infection, wasting syndrome in chronic illness, inflammatory bowel disease, multiple myeloma and some solid tumours. In 1998 the US Food and Drug Administration approved thalidomide exclusively for the treatment of ENL, and strict conditions were stipulated for its use in order to prevent teratogenic adverse effects. However, despite the promising findings of thalidomide at the molecular level, namely its anti-TNFalpha properties and its intercalation with DNA, and activity in clinical trials, there is still a great need for more intensive research.

Thalidomide: new indications?

Thalidomide, which was developed as a nonbarbiturate sedative agent, was taken off the market in 1961 after it was linked to a spate of major birth defects. Gradually, thalidomide was reintroduced for the treatment of a few skin diseases including leprous erythema nodosum, severe mucosal ulcers (e.g., associated with HIV infection or Behçet's disease), lymphocytic skin infiltrations, cutaneous lupus erythematosus, and chronic graft-versus-host disease. Recent reports of original pharmacological properties including modulation of cytokine production (mainly reduced TNF-alpha production) and inhibition of angiogenesis have led to the suggestion that thalidomide may be useful in some inflammatory and neoplastic conditions. Several open-label studies and case reports have described the effects of thalidomide in Crohn's disease, rheumatoid arthritis, ankylosing spondylarthritis, systemic sclerosis, and a few other systemic disorders. In these indications, minor but dose-limiting side effects were apparently common. Thalidomide analogs with better acceptability profiles are under evaluation. The anti-angiogenic effects of thalidomide may make this compound valuable as single-drug therapy or as an adjunct to chemotherapy in patients with cancer, particularly those with metastases or multiple myeloma. This possibility requires further evaluation.

Phase II study of the antiangiogenesis agent thalidomide in recurrent or metastatic squamous cell carcinoma of the head and neck

BACKGROUND

Thalidomide has been shown to have antiangiogenic effects in preclinical models as well as a significant antitumor effect in hematologic tumors such as multiple myeloma. The authors performed this Phase II study to determine the activity, toxicity profile, and antiangiogenic effect of thalidomide in patients with locoregionally recurrent or metastatic squamous cell carcinoma of the head and neck.

METHODS

Twenty-one patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with single-agent thalidomide. All patients had received radiation therapy, and most had undergone surgery (95%) and/or chemotherapy (90%). Thalidomide was initiated at 200 mg;3>daily and increased to a target dose of 1000 mg daily. Patients continued treatment until disease progression, unacceptable toxicity, or death occurred.

RESULTS

All 21 patients eventually developed progressive disease. Median time to progression was 50 days (95% confidence interval, 28-70), with median overall survival time of 194 days (95% lower confidence boundary, 151), similar to the progression and survival times reported for this patient group with other agents. Thalidomide was generally well tolerated, with few patients experiencing Grades 3 to 4 toxicities. Serum vascular endothelial growth factor and basic fibroblast growth factor levels increased in six of seven patients, for whom paired serum samples were available and all of whom had progressive disease.

CONCLUSIONS

In this heavily pretreated population of patients with advanced squamous cell carcinoma of the head and neck, thalidomide does not appear to have single-agent antitumor activity. Further evaluation of the mechanism of action of thalidomide is indicated. Potentially, future evaluations of thalidomide may be performed in combination with other antiangiogenic or cytotoxic agents in patients with earlier stage disease or in patients with minimal residual disease.

Gliomatosis cerebri: post-mortem molecular and immunohistochemical analyses in a case treated with thalidomide

Gliomatosis cerebri (GC) is a rare tumor of the central nervous system (CNS) characterized by widespread diffuse infiltration of the brain and spinal cord by neoplastic glial cells. We report the case of a 17-year-old boy with a bioptically diagnosed fibrillary astrocytoma. The administration of thalidomide, which was suggested to be beneficial in the treatment of human cancers, had no substantial clinical effect on our patient. Autopsy studies revealed a diffuse infiltration of the frontal and temporal lobes of the right hemisphere, brainstem, and the leptomeninges covering the whole spinal cord by an astrocytic tumor, which showed features both of low-grade astrocytoma and glioblastoma multiforme. No mutations in the p53 and PTEN tumor suppressor genes were found; immunoreactivities for p53, PTEN, and EGFR could not be detected.

Integrating anti-tumor necrosis factor therapy in inflammatory bowel disease: current and future perspectives

Crohn's disease and ulcerative colitis are two idiopathic inflammatory disorders of the GI tract. Manifestations of disease can be severe and lead to long term therapy with a variety of medications and/or surgery. Standard medical therapy consists of agents that either treat suppurative complications or modulate the inflammatory cascade in a nonspecific manner. Many specific chemokine and cytokine effectors that promote intestinal inflammation have been identified. Such work has led to experimental clinical trials with a variety of cytokine antagonists. Compounds directed against one such cytokine, tumor necrosis factor alpha (TNF), have demonstrated the greatest clinical efficacy to date. This is consistent with scientific observations that suggest a central role for TNF in the inflammatory cascade. Infliximab is a chimeric monoclonal antibody against TNF that has been demonstrated to be effective for the treatment of Crohn's disease. Infliximab is Food and Drug Administration approved for the treatment of Crohn's disease. There exist several other TNF antagonists in various phases of investigation, including the monoclonal antibody CDP 571, the fusion peptide etanercept, the phosphodiesterase inhibitor oxpentifylline, and thalidomide. The clinical efficacy of these agents and the role of TNF in the pathogenesis of inflammatory bowel disease is reviewed.

General aspects of anti-angiogenesis and cancer therapy

Angiogenesis is the outgrowth of new vessels from pre-existing ones. Tumour growth and metastasis is dependent on angiogenesis and many stimulatory and inhibitory factors have been described which play an active role in this process. Inhibition of tumour neovasculature may be one strategy to inhibit tumour growth. Naturally occurring inhibitors of angiogenesis have been discovered and synthetic agents have been designed. Many of these inhibitors are currently being evaluated in clinical trials for the treatment of cancer. This review discusses the mechanism of action of these anti-angiogenics as well as a description of the clinical trials in which they are being evaluated.

Current prospects for controlling cancer growth with non-cytotoxic agents--nutrients, phytochemicals, herbal extracts, and available drugs

In animal or cell culture studies, the growth and spread of cancer can be slowed by many nutrients, food factors, herbal extracts, and well-tolerated, available drugs that are still rarely used in the clinical management of cancer, in part because they seem unlikely to constitute definitive therapies in themselves. However, it is reasonable to expect that mechanistically complementary combinations of these measures could have a worthwhile impact on survival times and, when used as adjuvants, could improve the cure rates achievable with standard therapies. The therapeutic options available in this regard include measures that: down-regulate serum free IGF-I; suppress the synthesis of mevalonic acid and/or certain derivatives thereof; modulate arachidonate metabolism by inhibiting 5-lipoxygenase, 12-lipoxygenase, or COX-2; antagonize the activation of AP-1 transcription factors; promote the activation of PPAR-gamma transcription factors; and that suppress angiogenesis by additional mechanisms. Many of these measures appear suitable for use in cancer prevention.

Mechanism of action in thalidomide teratogenesis

In this commentary, we describe a model to explain the mechanism of the embryopathy of thalidomide. We propose that thalidomide affects the following pathway during development: insulin-like growth factor I (IGF-I) and fibroblast growth factor 2 (FGF-2) stimulation of the transcription of alphav and beta3 integrin subunit genes. The resulting alphavbeta3 integrin dimer stimulates angiogenesis in the developing limb bud, which promotes outgrowth of the bud. The promoters of the IGF-I and FGF-2 genes, the genes for their binding proteins and receptors, as well as the alphav and beta3 genes, lack typical TATA boxes, but instead contain multiple GC boxes (GGGCGG). Thalidomide, or a breakdown product of thalidomide, specifically binds to these GC promoter sites, decreasing transcription efficiency of the associated genes. A cumulative decrease interferes with normal angiogenesis, which results in truncation of the limb. Intercalation into G-rich promoter regions of DNA may explain why certain thalidomide analogs are not teratogenic while retaining their anti-tumor necrosis factor-alpha (TNF-alpha) activity, and suggests that we look elsewhere to explain the action of thalidomide on TNF-alpha. On the other hand, the anti-cancer action of thalidomide may be based on its antiangiogenic action, resulting from specific DNA intercalation. The tissue specificity of thalidomide and its effect against only certain neoplasias may be explained by the fact that various developing tissues and neoplasias depend on different angiogenesis or vasculogenesis pathways, only some of which are thalidomide-sensitive.

Antiangiogenic strategies and agents in clinical trials

The understanding that the growth of tumors depends on the acquisition of a blood supply has led to the development of new therapies for cancer and other angiogenic diseases based on inhibition of neovascularization. This review examines the role of angiogenesis in cancer progression and describes various strategies for interfering with this process. The developmental status of angiogenesis inhibitors in human clinical trials is presented, including their proposed mechanisms of action. Standard chemotherapeutic agents and angiogenesis inhibitors are compared, noting that different end points might need to be considered in clinical trials and that drug resistance may be less of a problem with antiangiogenic therapy than with conventional chemotherapy regimens. The suggestion is made that cytotoxic chemotherapy and angiogenesis inhibitors used in combination may produce complementary therapeutic benefits in the treatment of cancer.

Antiangiogenic tumour therapy: will it work?

The inhibition of angiogenesis is considered to be one of the most promising strategies that might lead to the development of novel antineoplastic therapies. This concept is supported by the dramatic results of gene inactivation experiments in mice that have identified several vascular endothelium related molecules as rate limiting for embryonic angiogenesis. Likewise, a number of recent animal studies have shown that angiogenesis inhibitors can prevent metastasis and shrink established experimental tumours to small dormant microtumours. In this review, Hellmut Augustin illustrates differences between developmental angiogenesis, physiological angiogenesis in the adult, and pathological angiogenesis in experimental animal tumours and natural human tumours. He then summarizes the experimental approaches to antiangiogenic therapies and finally discusses critical issues that need to be considered in translating these novel therapeutic strategies into clinical practice.

Selenium, calcium channel blockers, and cancer risk--the Yin and Yang of apoptosis?

It is increasingly clear that apoptosis plays a crucial role in the promotional phase of cancer development. Initiated pre-neoplastic clones in rat liver experience a high rate of apoptosis, and this rate has an important impact on the survival and growth of these clones. Suppression of apoptosis appears to be a universal property of cancer promoters, suggesting conversely that agents which inhibit cancer induction during the promotional phase increase the rate of apoptosis in initiated cells. Modulation of apoptosis is a likely explanation for recent striking evidence that use of calcium channel blockers substantially increases, whereas supplemental selenium substantially decreases, human cancer incidence. Non-genotoxic measures which are likely to upregulate apoptosis in pre-neoplastic/neoplastic cells--and thus may be useful in prevention and/or therapy--include selenium, retinoids/carotenoids, green tea polyphenols, caloric restriction, downregulation of IGF-I activity, high-dose tamoxifen and other protein kinase C antagonists, withdrawal or blockade of trophic hormones, isoflavones, limonene, vitamin D and cholecalciferol analogs, dietary fiber/sodium butyrate, hyperthermia, benzaldehyde derivatives, and creatine.