51
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Cai W, Sam Gambhir S, Chen X. Multimodality tumor imaging targeting integrin αvβ3. Biotechniques 2005; 39:S14-25. [DOI: 10.2144/000112091] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The cell adhesion molecule integrin αvβ3 is an important player in the process of tumor angiogenesis and metastasis. Antibodies, peptides, peptidomimetics, and small molecule antagonists against integrin αvβ3 have been shown to induce endothelial apoptosis, to inhibit tumor angiogenesis, and to increase endothelial permeability. The ability to quantitatively image integrin αvβ3 expression in vivo in a noninvasive manner may shed new light into the mechanism of angiogenesis and antiangiogenic treatment efficacy based on integrin antagonism. Tumor integrin expression imaging will also aid in lesion detection, patient stratification, new anti-integrin drug development/validation, as well as treatment monitoring and optimization. This review summarizes the recent advances in multimodality imaging of tumor integrin αvβ3 expression using magnetic resonance imaging (MRI), ultrasound, near-infrared (NIR) fluorescence, single photon emission computed tomography (SPECT), and positron emission tomography (PET).
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Affiliation(s)
- Weibo Cai
- Stanford University School of Medicine, Stanford, CA, USA
| | | | - Xiaoyuan Chen
- Stanford University School of Medicine, Stanford, CA, USA
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52
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Akalu A, Cretu A, Brooks PC. Targeting integrins for the control of tumour angiogenesis. Expert Opin Investig Drugs 2005; 14:1475-86. [PMID: 16307488 DOI: 10.1517/13543784.14.12.1475] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The crucial role of cell extracellular matrix communication in angiogenesis is well established; thus, it is not surprising that integrins have gained considerable attention as targets for the treatment of neovascular disease. Given the diversity of ligands and complexity of integrin signalling, a new appreciation for the divergent roles of integrins in angiogenesis is emerging. It is becoming clear that integrins regulate angiogenesis in both a positive and negative manner. New studies have provided a better understanding of integrin structure as it relates to ligand binding and signalling. This new insight has opened exciting possibilities for the design of novel inhibitors for clinical applications. In this review, studies concerning the cooperative interactions between integrins and regulatory molecules and possible new strategies for controlling angiogenesis will be discussed.
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Affiliation(s)
- Abebe Akalu
- Department of Radiation Oncology, Cancer Institute, New York University School of Medicine, New York, NY 10016, USA
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53
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Abstract
Many novel antiangiogenic agents are currently in various phases of clinical testing. These agents tend to be cytostatic, and therefore few responses are observed with conventional imaging by computerized tomography. Furthermore, toxicity with these agents is seen when the maximum-tolerated dose is combined with chemotherapy. Hence, there is a need to develop imaging strategies that can determine the minimum and optimum biologically active doses. There is increasing awareness of the need to obtain evidence of drug activity through the use of surrogate markers of the biologic mechanism of action during early clinical trials, in addition to determining the pharmacokinetics, toxicity profile, and maximum-tolerated dose. One of the major impediments to the rapid development of antiangiogenic agents in the past has been the lack of validated assays capable of measuring an antiangiogenic effect directly in patients. Recently, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has emerged as a useful technique for noninvasive imaging of tumor vasculature in preclinical and clinical models. The problem of tumor heterogeneity remains to be addressed. The major challenge is the standardization of the technique worldwide for the purpose of early clinical studies that are likely to be multicenter. Convincing data on correlations between changes observed through molecular imaging and changes in tumor angiogenesis, and hence tumor biology, are still lacking. Whether this would translate into a survival advantage remains to be seen. The ultimate test of the surrogate biological end points determined by molecular imaging will occur in randomized phase III trials. Results of the first randomized trial that showed a survival advantage in favor of antiangiogenic agents were released at the American Society of Clinical Oncology meeting in 2003. There it was reported that the combination of 5-fluorouracil, leucovorin, and irinotecan (Camptosar; Pfizer Pharmaceuticals; New York, NY) with anti-vascular endothelial growth factor antibody (bevacizumab-Avastin; Genentech, Inc.; South San Francisco, CA) was superior to the chemotherapy regimen alone when used to treat patients with metastatic colorectal cancer. However, until further phase III clinical trials confirm these results, surrogate end points of clinical efficacy of the newer agents are urgently needed so that development of ineffective drugs can be halted early. This review briefly discusses the role of molecular imaging in general, and DCE-MRI in particular, in relation to treatment with antiangiogenic agents and highlights some of the difficulties encountered in this area.
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Affiliation(s)
- Shazza Rehman
- Cancer Research UK, Department of Medical Oncology, Christie Hospital NHS Trust, Wilmslow Road, Manchester, M20 4BX, United Kingdom.
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54
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Abstract
Cell adhesion and migration are essential for embryonic development, tissue regeneration, but also for tumor development. The physical link between the extracellular matrix (ECM) and the actin cytoskeleton is mainly mediated by receptors of the integrin family. Through signals transduced upon integrin ligation to ECM proteins, this family of proteins plays key roles in regulating tumor growth and metastasis as well as tumor angiogenesis. During melanoma development, changes in integrin expression, intracellular control of integrin functions and signals perceived from integrin ligand binding impact upon the ability of tumor cells to interact with their environment and enable melanoma cells to convert from a sessile, stationary to a migratory and invasive phenotype. Antagonists of several integrins are now under evaluation in clinical trials to determine their potential as therapeutics for malignant melanoma and other kinds of cancer.
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Affiliation(s)
- Silke Kuphal
- Institute of Pathology, University of Regensburg, Germany
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55
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Abstract
Treatment with antiangiogenic agents as standard anticancer therapy with or without classical chemotherapy is rapidly approaching. The clinical efficacy of bevacizumab in colorectal cancer in combination with chemotherapy caused a revival of the antiangiogenic strategy. By combining this agent with a tyrosine kinase receptor epidermal growth factor receptor blocker (erlotinib), remarkable responses were seen in renal cell cancer. It has been thought that blocking these biological pathways would cause no drug-related toxicity, but a whole new pattern of relatively mild side effects compared with classical chemotherapy, including skin rash, fatigue and hypertension, has been observed. In combination with chemotherapy, other serious side effects, such as bleeding and thrombosis, also occur. Here, the preclinical and clinical data of antiangiogenic agents in clinical trials at this moment are summarised.
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Affiliation(s)
- Henk M W Verheul
- Dept of Internal Medicine, University Medical Center, Utrecht, The Netherlands
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56
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Abstract
A large proportion of patients with advanced hepatocellular carcinoma (HCC) lack effective therapy. Due to chemoresistance, hope has focused on other approaches including targeted therapies, immune stimulants, and the emerging area of gene therapy. Increasing efforts in basic and clinical development of these approaches will hopefully result in more efficient therapies against HCC.
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Affiliation(s)
- Bruno Sangro
- The Liver Unit, Clínica Universitaria de Navarra, Fundación para la Investigación Médica Aplicada, University of Navarra, Pamplona, Spain.
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57
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Verheul HMW, Pinedo HMW. Angiogenesis inhibitors: what is the clinical future? PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2005; 63:67-91. [PMID: 16265877 DOI: 10.1007/3-7643-7414-4_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Henk M W Verheul
- Department of Medical Oncology, Johns Hopkins University, 1650 Orleans Street CRB 162, Baltimore, MD 21231, USA.
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58
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Akhtar N, Padilla ML, Dickerson EB, Steinberg H, Breen M, Auerbach R, Helfand SC. Interleukin-12 inhibits tumor growth in a novel angiogenesis canine hemangiosarcoma xenograft model. Neoplasia 2004; 6:106-16. [PMID: 15140399 PMCID: PMC1502086 DOI: 10.1593/neo.03334] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We established a canine hemangiosarcoma cell line derived from malignant endothelial cells comprising a spontaneous tumor in a dog to provide a renewable source of endothelial cells for studies of angiogenesis in malignancy. Pieces of the hemangiosarcoma biopsy were engrafted subcutaneously in a bg/nu/XID mouse allowing the tumor cells to expand in vivo. A cell line, SB-HSA, was derived from the xenograft. SB-HSA cells expressed vascular endothelial growth factor (VEGF) receptors 1 and 2, CD31, CD146, and alpha(v)beta(3) integrin, and produced several growth factors and cytokines, including VEGF, basic fibroblast growth factor, and interleukin (IL)-8 that are stimulatory to endothelial cell growth. These results indicated that the cells recapitulated features of mitotically activated endothelia. In vivo, SB-HSA cells stimulated robust angiogenic responses in mice and formed tumor masses composed of aberrant vascular channels in immunocompromised mice providing novel opportunities for investigating the effectiveness of antiangiogenic agents. Using this model, we determined that IL-12, a cytokine with both immunostimulatory and antiangiogenic effects, suppressed angiogenesis induced by, and tumor growth of, SB-HSA cells. The endothelial cell model we have described offers unique opportunities to pursue further investigations with IL-12, as well as other antiangiogenic approaches in cancer therapy.
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MESH Headings
- Animals
- Biomarkers, Tumor/metabolism
- Cell Adhesion
- Cell Division
- Corneal Neovascularization/drug therapy
- Corneal Neovascularization/metabolism
- Corneal Neovascularization/pathology
- Cytokines/metabolism
- Dogs
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Flow Cytometry
- Growth Substances/metabolism
- Hemangiosarcoma/blood supply
- Hemangiosarcoma/pathology
- Interleukin-12/therapeutic use
- Mice
- Mice, Inbred BALB C
- Mice, Inbred NOD
- Mice, SCID
- Neoplasm Transplantation
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Reverse Transcriptase Polymerase Chain Reaction
- Soft Tissue Neoplasms/blood supply
- Soft Tissue Neoplasms/pathology
- Transplantation, Heterologous
- Tumor Cells, Cultured
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Affiliation(s)
- Nasim Akhtar
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
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59
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Abstract
Integrins are cell adhesion molecules that play an important role in the regulation of angiogenesis. In this overview, the vascular integrins and their mechanisms of action are outlined. Integrins have been evaluated in preclinical and clinical studies for the treatment of cancer and as diagnostic markers of angiogenesis. Furthermore, integrins are the basis for targeted therapy for solid tumors and novel imaging techniques to assess the angiogenic response of tumors.
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Affiliation(s)
- Rosa Hwang
- Department of Surgery, University of California San Diego, Moores Comprehensive Cancer Center, 9500 Gilman Drive, La Jolla, CA 92093-0987, USA
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60
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Trikha M, Zhou Z, Nemeth JA, Chen Q, Sharp C, Emmell E, Giles-Komar J, Nakada MT. CNTO 95, a fully human monoclonal antibody that inhibits alphav integrins, has antitumor and antiangiogenic activity in vivo. Int J Cancer 2004; 110:326-35. [PMID: 15095296 DOI: 10.1002/ijc.20116] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Integrins of the alphav family, such as alphavbeta3 and alphavbeta5, are implicated in tumor-induced angiogenesis; but their role in tumor growth has not been fully explored. CNTO 95 is a fully human antibody that recognizes the alphav family of integrins and is likely to be less immunogenic in humans compared to chimeric or humanized antibodies. CNTO 95 bound to purified alphavbeta3 and alphavbeta5 with a Kd of approximately 200 pM and to alphav integrin-expressing human cells with a Kd of 1-24 nM. In vitro, CNTO 95 inhibited human melanoma cell adhesion, migration and invasion at doses ranging 7-20 nM. In a rat aortic ring sprouting assay, CNTO 95 (approx. 70 nM) completely inhibited sprouting. Using a human melanoma xenograft model in nude mice wherein CNTO 95 recognized alphavbeta3 and alphavbeta5 on human tumor cells but not mouse angiogenic integrins, CNTO 95 (10 mg/kg, 3 times/week) inhibited growth of human melanoma tumors in nude mice by approximately 80% (p = 0.0005), suggesting that CNTO 95 inhibited human tumor growth independently of its antiangiogenic activity. In a nude rat human xenograft model where CNTO 95 binds and blocks both tumor and host integrins, this antibody (10 mg/kg once/week) reduced final tumor weight by >99% (p < 0.0001). Based on these preclinical data, a dose-escalating phase I clinical trial in cancer patients has been initiated. To our knowledge, CNTO 95 is the first fully human MAb to alphav integrins that has potent antitumor and antiangiogenic properties in in vivo preclinical models.
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MESH Headings
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized
- Antibody Affinity
- Antibody Specificity
- Antineoplastic Agents/pharmacology
- Aorta/metabolism
- Aorta/pathology
- Blotting, Western
- Cattle
- Cell Adhesion
- Cell Division
- Cell Line
- Cell Line, Tumor
- Cell Movement
- Cells, Cultured
- Collagen/pharmacology
- Dose-Response Relationship, Drug
- Drug Combinations
- Endothelium, Vascular/cytology
- Fibroblast Growth Factor 2/metabolism
- Haplorhini
- Humans
- Integrin alphaV/chemistry
- Integrin alphaVbeta3/metabolism
- Integrins/metabolism
- Kinetics
- Laminin/pharmacology
- Macaca fascicularis
- Melanoma/immunology
- Melanoma/therapy
- Mice
- Mice, Nude
- Neoplasm Invasiveness
- Neoplasm Transplantation
- Neovascularization, Pathologic
- Placenta/metabolism
- Placenta/pathology
- Protein Binding
- Proteoglycans/pharmacology
- Rats
- Rats, Nude
- Receptors, Vitronectin/metabolism
- Time Factors
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61
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Trochon-Joseph V, Martel-Renoir D, Mir LM, Thomaïdis A, Opolon P, Connault E, Li H, Grenet C, Fauvel-Lafève F, Soria J, Legrand C, Soria C, Perricaudet M, Lu H. Evidence of antiangiogenic and antimetastatic activities of the recombinant disintegrin domain of metargidin. Cancer Res 2004; 64:2062-9. [PMID: 15026344 DOI: 10.1158/0008-5472.can-03-3272] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Metargidin, a transmembrane protein of the adamalysin family, and integrins, e.g., alpha5beta1 and alphav, are preferentially expressed on endothelial cells on angiogenesis. Furthermore, metargidin interacts with these integrins via its disintegrin domain. In this study, recombinant human disintegrin domain (RDD) was produced in Escherichia coli by subcloning its cDNA into the pGEX-2T vector, and the effect of purified RDD on different steps of angiogenesis was evaluated. At concentrations of 2-10 micro g/ml, RDD exhibited inhibitory activities in a variety of in vitro functional assays, including endothelial cell proliferation and adhesion on the integrin substrates fibronectin, vitronectin, and fibrinogen. RDD (10 micro g/ml) totally abrogated endothelial cell migration and blocked most capillary formation in a three-dimensional fibrin gel. To test RDD efficacy in vivo, the RDD gene inserted into pBi vector containing a tetracycline-inducible promoter was electrotransferred into nude mouse muscle. RDD was successfully synthesized by muscle cells in vivo as shown by immunolabeling and Western blotting. In addition, 78% less MDA-MB-231 tumor growth, associated with strong inhibition of tumor angiogenesis, was observed in athymic mice bearing electrotransferred RDD. Moreover, in the presence of RDD, 74% fewer B16F10 melanoma lung metastases were found in C57BL/6 mice. Taken together, these results identified this RDD as a potent intrinsic inhibitor of angiogenesis, tumor growth, and metastasis, making it a promising tool for use in anticancer treatment.
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MESH Headings
- ADAM Proteins
- Animals
- Antineoplastic Agents/therapeutic use
- Apoptosis/drug effects
- Cell Adhesion/drug effects
- Cell Division/drug effects
- Cell Movement/drug effects
- Disintegrins/therapeutic use
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/pathology
- Escherichia coli/genetics
- Female
- Lung Neoplasms/blood supply
- Lung Neoplasms/prevention & control
- Lung Neoplasms/secondary
- Melanoma, Experimental/blood supply
- Melanoma, Experimental/prevention & control
- Melanoma, Experimental/secondary
- Membrane Proteins/therapeutic use
- Metalloendopeptidases/therapeutic use
- Mice
- Mice, Inbred C57BL
- Mice, Nude
- Muscle, Skeletal/pathology
- Neovascularization, Pathologic/prevention & control
- Recombinant Proteins/therapeutic use
- Tumor Cells, Cultured
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62
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Miller KD. Recent translational research: antiangiogenic therapy for breast cancer - where do we stand? Breast Cancer Res 2004; 6:128-32. [PMID: 15084233 PMCID: PMC400679 DOI: 10.1186/bcr782] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 03/04/2004] [Indexed: 01/13/2023] Open
Abstract
The central importance of angiogenesis and our understanding of how new blood vessels are formed have led to the development of novel antiangiogenic therapies. Although the number of agents in development has grown exponentially, only one phase III trial in breast cancer has been completed. In that study the addition of bevacizumab to capecitabine did not extend the progression-free survival of patients with refractory disease as compared with capecitabine monotherapy. Early enthusiasm for antiangiogenic therapy must give way to clinical reality. Our challenge now is to exploit better the activity of antiangiogenic agents seen in the early clinical studies.
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63
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Abstract
The integrin family of cell adhesion proteins promotes the attachment and migration of cells on the surrounding extracellular matrix (ECM). Through signals transduced upon integrin ligation by ECM proteins or immunoglobulin superfamily molecules, this family of proteins plays key roles in regulating tumour growth and metastasis as well as tumour angiogenesis. Several integrins play key roles in promoting tumour angiogenesis and tumour metastasis. Antagonists of several integrins (alpha5beta1, alphavbeta3 and alphavbeta5) are now under evaluation in clinical trials to determine their potential as therapeutics for cancer and other diseases.
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Affiliation(s)
- H Jin
- John and Rebecca Moores Comprehensive Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0912, USA
| | - J Varner
- John and Rebecca Moores Comprehensive Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0912, USA
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0912, USA
- John and Rebecca Moores Comprehensive Cancer Center, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0912, USA. E-mail:
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64
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Eskens FALM. Angiogenesis inhibitors in clinical development; where are we now and where are we going? Br J Cancer 2004; 90:1-7. [PMID: 14710197 PMCID: PMC2395335 DOI: 10.1038/sj.bjc.6601401] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2003] [Revised: 09/04/2003] [Accepted: 09/12/2003] [Indexed: 11/30/2022] Open
Abstract
Angiogenesis is crucial for tumour growth and the formation of metastases. Various classes of angiogenesis inhibitors that are each able to inhibit one of the various steps of this complex process can be distinguished. Results from clinical studies with these agents are summarised. In general, it has been shown that most angiogenesis inhibitors can be safely administered, but that tumour regressions are rare. Combining angiogenesis inhibitors with cytotoxic chemotherapy can enhance anticancer activity. Recently, some promising data with regard to clinical efficacy have been presented. While performing clinical studies with angiogenesis inhibitors, defining biological activity is crucial, but thus far no validated techniques are available. It is conceivable that in the near future various classes of angiogenesis inhibitors will be combined in an attempt to further improve antiangiogenic and anticancer activity.
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Affiliation(s)
- F A L M Eskens
- 1Department of Medical Oncology, Erasmus University Medical Center, PO Box 2040, Rotterdam 3000 CA, The Netherlands.
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65
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Abstract
Multidisciplinary treatment strategies for patients with malignant brain tumors have resulted in only small gains in terms of prognosis in spite of the use of aggressive therapy. There is a growing realization that a paradigm shift is needed in the conceptual approaches to glioma therapy. Such approaches will rely on identification and modification of key cellular targets that define the biological behavior of these tumors. Among the targets for such treatment approaches, tumor angiogenesis has captured the attention of not only the medical field but also of the lay public because of its conceptual departure from traditional methods of cancer therapy. Angiogenesis and vascular proliferation are particularly important in the growth and progression of malignant gliomas and are used as indicators of the degree of malignancy. Recent studies have helped us gain a better understanding of the molecular mediators of this process. It is now evident that after the initial formation of malignancy the continued growth of a glioma is critically dependent on its angiogenic potential. Hence, several approaches to control angiogenesis are being developed and tested. Preliminary results from clinical studies have shown that angiogenesis inhibition is a valid approach as a therapeutic strategy against gliomas but it is also becoming evident that inhibition of individual modulators of this process may not yield the expected impact on prognosis. To fully realize the potential of antiangiogenic therapy, a deeper understanding of the interplay between the tumor vasculature and its environment is needed. Angiogenesis inhibitors have made the transition from preclinical studies to the clinical arena; it remains for ongoing human trials of such agents to fully explore the feasibility and efficacy of these agents in order to exploit the potential of this approach.
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Affiliation(s)
- Vinay K Puduvalli
- Department of Neuro-oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, 77030, USA
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66
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Espinosa E, Zamora P, Feliu J, González Barón M. Classification of anticancer drugs—a new system based on therapeutic targets. Cancer Treat Rev 2003; 29:515-23. [PMID: 14585261 DOI: 10.1016/s0305-7372(03)00116-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The arrival of a great number of new antineoplastic agents has made it necessary to reclassify all of them. Anticancer drugs may act at different levels: cancer cells, endothelium, extracellular matrix, the immune system or host cells. The tumour cell can be targeted at the DNA, RNA or protein level. Most classical chemotherapeutic agents interact with tumour DNA, whereas monoclonal antibodies and small molecules are directed against proteins. The endothelium and extracellular matrix may be affected also by specific antibodies and small molecules.
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67
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Abstract
Improvements in surgical techniques, for example reconstructive surgery; and radiation therapy techniques, such as intensity-modulated radiotherapy; have made some impact on the functional outcomes of sarcomas with a local biology. Effective local control can be achieved with effective function in the vast majority of patients. The problem of distant metastases, however, continues to plague a large group of patients with this disease. Recent advances in the systemic therapy of sarcomas is highlighted by the rapid development and approval of the molecularly targeted therapy imatinib (Gleevec) for advanced gastrointestinal stromal tumors. Several other agents have been, or are being studied with far less rewarding results. Among these, the more encouraging examples include the nucleoside analog gemcitabine (Gemzar) and gemticibine/docetaxel (Taxotere) in combination, which display some selective activity in sarcomas of gynecologic origin. The marine compound ecteinascidin (ET-743) has been studied in two different schedules (24 and 3 h infusions), demonstrating biological activity worthy of further investigation. Identification of new agents with activity in this diverse group of diseases is extremely important. Identification of specific targets responsible for tumorigenesis and effective inhibition of these targets holds the most promise for future improvement in cure rates. However, until such time, it is equally important to emphasize clinical research attempting to further optimize the use of the standard chemotherapeutic agents, with growth-factor support in appropriately selected patients.
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Affiliation(s)
- Shreyaskumar R Patel
- Department of Sarcoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston 77030, USA.
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68
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Schraa AJ, Kok RJ, Moorlag HE, Bos EJ, Proost JH, Meijer DKF, de Leij LFMH, Molema G. Targeting of RGD-modified proteins to tumor vasculature: a pharmacokinetic and cellular distribution study. Int J Cancer 2002; 102:469-75. [PMID: 12432548 DOI: 10.1002/ijc.10727] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Angiogenesis-associated integrin alpha(v)beta(3) represents an attractive target for therapeutic intervention because it becomes highly upregulated on angiogenic endothelium and plays an important role in the survival of endothelial cells. Cyclic RGD peptides were prior shown to have a high affinity for alpha(v)beta(3) and can induce apoptosis of endothelial cells. In our laboratory, monocyclic RGD peptides (cRGDfK) were chemically coupled to a protein backbone. Previous results demonstrated that the resulting RGDpep-HuMab conjugate bound with increased avidity to alpha(v)beta(3)/alpha(v)beta(5) on endothelial cells. In our present study, RGDpep-HuMab was injected intravenously and intraperitoneally in B16.F10 tumor-bearing mice to determine its pharmacokinetics and organ distribution. In the tumor, the RGDpep-HuMab conjugate specifically localized at the endothelium as was demonstrated by immunohistochemistry. The control RADpep-HuMab conjugate was not detected in the tumor. Besides tumor localization RGDpep-HuMab was found in liver and spleen associated with macrophages. This uptake by macrophages is probably responsible for the more rapid clearance of RGDpep-HuMab from the circulation than HuMab and RADpep-HuMab. The half-life of RGDpep-HuMab (90 min) was still considerably longer than that of free RGD peptides (<10 min). This prolonged circulation time may be favorable for drug targeting strategies because the target cells are exposed to the conjugate for a longer time period. Taken together these results indicate that RGD-modified proteins are suitable carriers to deliver therapeutic agents into tumor or inflammation induced angiogenic endothelial cells.
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Affiliation(s)
- Astrid J Schraa
- Department of Pathology and Laboratory Medicine, Medical Biology Section, Tumor Immunology Laboratory, Groningen, The Netherlands.
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69
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Abstract
Antiangiogenic drugs are unique for having highly specific targets while carrying the potential to be effective against a wide variety of tumors. Moreover, some of the major limitations of cytotoxic therapies likely will be avoided by this entirely new class of anticancer weapons. After the realization of the potential advantages of antiangiogenic therapy, the field of angiogenesis research is growing exponentially. Still, there is much to learn about the machinery that tumors use to recruit new blood vessels, and the results of the clinical trials will show the best way to apply that knowledge for cancer therapy.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Angiogenesis Inhibitors/therapeutic use
- Angiostatins
- Animals
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/therapeutic use
- Anticarcinogenic Agents/pharmacology
- Anticarcinogenic Agents/therapeutic use
- Cell Hypoxia/physiology
- Child
- Clinical Trials as Topic
- Collagen/physiology
- Cyclooxygenase Inhibitors/pharmacology
- Cyclooxygenase Inhibitors/therapeutic use
- Drug Design
- Endostatins
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/pathology
- Ephrins/physiology
- Growth Substances/physiology
- Humans
- Immunotherapy
- Integrin alphaVbeta3/antagonists & inhibitors
- Integrin alphaVbeta3/physiology
- Ligases/physiology
- Matrix Metalloproteinase Inhibitors
- Matrix Metalloproteinases/physiology
- Mice
- Neoplasm Proteins/antagonists & inhibitors
- Neoplasm Proteins/physiology
- Neoplasms/blood supply
- Neoplasms/drug therapy
- Neovascularization, Pathologic/drug therapy
- Outcome Assessment, Health Care
- Peptide Fragments/physiology
- Plasminogen/physiology
- Protease Inhibitors/pharmacology
- Protease Inhibitors/therapeutic use
- Receptors, Eph Family/antagonists & inhibitors
- Receptors, Eph Family/physiology
- Receptors, Growth Factor/antagonists & inhibitors
- Receptors, Growth Factor/physiology
- Thrombospondins/physiology
- Tumor Suppressor Proteins
- Ubiquitin-Protein Ligases
- Von Hippel-Lindau Tumor Suppressor Protein
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Affiliation(s)
- Kerim Kaban
- Department of Thoracic Head and Neck Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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70
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Abstract
Targeting angiogenesis represents a new strategy for the development of anticancer therapies. New targets derived from proliferating endothelial cells may be useful in developing anticancer drugs that prolong or stabilize the progression of tumors with minimal systemic toxicities. These drugs may also be used as novel imaging and radiommunotherapeutic agents in cancer therapy. In this review, the mechanisms and control of angiogenesis are discussed. Genetic and proteomic approaches to defining new potential targets on tumor vasculature are then summarized, followed by discussion of possible antiangiogenic treatments that may be derived from these targets and current clinical trials. Such strategies involve the use of endogenous antiangiogenic agents, chemotherapy, gene therapy, antiangiogenic radioligands, immunotherapy, and endothelial cell-based therapies. The potential biologic end points, toxicities, and resistance mechanisms to antiangiogenic agents must be considered as these therapies enter clinical trials.
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Affiliation(s)
- Frank A Scappaticci
- Department of Pathology, Stanford University Medical Center, Stanford, CA 94305, USA.
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Abstract
The field of oncology is experiencing a paradigm shift from broad-spectrum cytotoxic therapies to more specific molecularly based targeted therapies. The activity of imatinib mesylate in chronic myelogenous leukemia and gastrointestinal stromal tumors (GIST) has reinforced our faith in translational research and its potential impact on the cure of cancer and improvement in quality of life for patients. This breakthrough has been particularly exciting for the field of sarcoma and for patients with advanced GIST, for whom no other effective therapy was available. Unfortunately, as is becoming increasingly clear, cancer is a very complex problem with multiple mechanisms and pathways that function either independently or interdependently enabling cell survival. We are therefore far away from having solved the problem. Attempts at refining the currently available therapeutic armamentarium to maximize the therapeutic index (dose intensification with growth factor support) must continue in parallel with laboratory-based research identifying critical targets to be inhibited or blocked. Identification of new agents with some activity, such as gemcitabine and ecteinascidin (ET-743), is also of paramount importance.
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Affiliation(s)
- Shreyaskumar R Patel
- Department of Sarcoma Medical Oncology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Box 450, Houston 77030, USA.
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Price JT, Thompson EW. Mechanisms of tumour invasion and metastasis: emerging targets for therapy. Expert Opin Ther Targets 2002; 6:217-33. [PMID: 12223082 DOI: 10.1517/14728222.6.2.217] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The progression of a tumour from one of benign and delimited growth to one that is invasive and metastatic is the major cause of poor clinical outcome in cancer patients. The invasion and metastasis of tumours is a highly complex and multistep process that requires a tumour cell to modulate its ability to adhere, degrade the surrounding extracellular matrix, migrate, proliferate at a secondary site and stimulate angiogenesis. Knowledge of the process has greatly increased and this has resulted in the identification of a number of molecules that are fundamental to the process. The involvement of these molecules has been shown to relate not only to the survival and proliferation of the tumour cell but, also to the processes of tumour cell adhesion, migration, and the tumour cells ability to degrade and escape the primary site as well as play a role in angiogenesis. These molecules may provide important therapeutic targets that represent the ability to target specific steps in the process of invasion and metastasis and provide additional therapies. The review focuses on representative key targets in each of these processes and summarises the state of play in each case.
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Affiliation(s)
- John T Price
- Bone Metastasis and Cell Migration Laboratory, St Vincent's Institute of Medical Research, Department of Surgery, University of Melbourne, St. Vincent's Hospital, Fitzroy, Melbourne, VIC 3065, Australia.
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