Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1658953 (tumor vasculature)
 2,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported that breast cancer cells which overexpress HER2 produce higher levels of VEGF than cells with low levels of HER2. This study tested the hypothesis that dual targeting of the VEGF (with VEGF-Trap) and HER2 (with trastuzumab) pathways would result in greater growth inhibition of HER2-overexpressing breast cancer xenografts than either agent alone. In this study we found that human and murine endothelial cells expressed high levels of VEGF receptors (VEGFR1, VEGFR2, & VEGFR3). VEGF-Trap decreased levels of secreted VEGF derived from both human and murine cells and effectively blocked VEGF-induced tyrosine phosphorylation of VEGFR2. VEGF-Trap as a single treatment inhibited tumor microvessel density (MVD), tumor vasculature, cell proliferation and tumor growth of BT474 xenografts in a dose-dependent manner from 2.5 mg/kg to 25 mg/kg. VEGF-Trap decreased levels of both human VEGF and PlGF protein in vivo. Trastuzumab as a single agent effectively inhibited BT474 tumor growth in a dose-dependent manner, associated with a decrease in human VEGF, tumor MVD and tumor cell proliferation. Treatment with a combination of VEGF-Trap (2.5-10 mg/kg) and trastuzumab (1 mg/kg) produced significantly greater inhibition of BT474 tumor growth than either individual agent, associated with greater inhibition of tumor MVD and tumor cell proliferation. Thus, VEGF-Trap in combination with trastuzumab produces superior growth inhibition of tumor xenografts which overexpress HER2, which may result from inhibition of both tumor angiogenesis and proliferation. Similar mechanisms may contribute to the clinical anti-tumor activity of trastuzumab in combination with inhibitors of VEGF signaling pathway in women with breast cancers which overexpress HER2.
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PMID:Specific blockade of VEGF and HER2 pathways results in greater growth inhibition of breast cancer xenografts that overexpress HER2. 1902 32

Most children with neuroblastoma presenting after infancy have metastatic, chemoresistant disease. Amplification of the MYCN proto-oncogene is a significant marker of these poor-prognosis neuroblastoma tumors. Recent studies suggest that MYCN may function in part by promoting angiogenesis via vascular endothelial growth factor (VEGF). VEGF blockade has been validated as a therapeutic strategy in adult cancers. In these studies, we asked whether inhibition of VEGF signaling via VEGFR2 blockade in established MYCN-amplified neuroblastoma xenografts would: 1) restrict tumor growth; 2) induce hypoxia; and 3) alter tumor vasculature. The MYCN-amplified neuroblastoma human cell line NGP was implanted intrarenally in athymic female mice. After 5 weeks, mice with established tumors were selected, a cohort euthanized to provide day 0 controls, and the rest assigned to receive biweekly injections of DC101 (anti-murine VEGFR2 antibody) or vehicle. DC101 treatment did not inhibit progressive tumor growth in established NGP xenografts. Although tumor vasculature was not significantly disrupted, a modest increase in tumor hypoxia was demonstrated by pimonidazole staining, and expression of a previously described hypoxia metagene was increased by gene set enrichment analysis (GSEA) in DC101-treated tumors. DC101 treatment elicited increased: 1) expression of VEGFR1 and its ligand placental growth factor; and 2) increased Notch activation in tumor vasculature concurrent with expression of the Notch ligand Jagged1. This result suggests that established MYCN-amplified neuroblastoma tumors are relatively VEGF-independent, and display the ability to rapidly up-regulate hypoxia-responsive alternative proangiogenic mechanisms that may stabilize vasculature when VEGF is deficient.
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PMID:Vascular endothelial growth factor blockade rapidly elicits alternative proangiogenic pathways in neuroblastoma. 1914 74

Recent studies suggest that tumor-associated CD11b(+)Gr1(+) myeloid cells contribute to refractoriness to antiangiogenic therapy with an anti-VEGF-A antibody. However, the mechanisms of peripheral mobilization and tumor-homing of CD11b(+)Gr1(+) cells are unclear. Here, we show that, compared with other cytokines [granulocyte-macrophage colony stimulating factor (GM-CSF), stromal derived factor 1alpha, and placenta growth factor], G-CSF and the G-CSF-induced Bv8 protein have preferential expression in refractory tumors. Treatment of refractory tumors with the combination of anti-VEGF and anti-G-CSF (or anti-Bv8) reduced tumor growth compared with anti-VEGF-A monotherapy. Anti-G-CSF treatment dramatically suppressed circulating or tumor-associated CD11b(+)Gr1(+) cells, reduced Bv8 levels, and affected the tumor vasculature. Conversely, G-CSF delivery to animals bearing anti-VEGF sensitive tumors resulted in reduced responsiveness to anti-VEGF-A treatment through induction of Bv8-dependent angiogenesis. We conclude that, at least in the models examined, G-CSF expression by tumor or stromal cells is a determinant of refractoriness to anti-VEGF-A treatment.
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PMID:G-CSF-initiated myeloid cell mobilization and angiogenesis mediate tumor refractoriness to anti-VEGF therapy in mouse models. 1934 89

Vascular functions of PlGF remain poorly understood and controversial. Here, we show that tumor cell-derived PlGF-1 and PlGF-2 displayed significant remodeling effects on the tumor vasculature, leading to a normalized vascular phenotype and improved functions against leakage. In two murine tumor models, that is, T241 fibrosarcoma and Lewis lung carcinoma, stable expression of PlGF-1 and PlGF-2 in tumor cells resulted in significant reduction of tumor microvascular density and branch formation. Markedly, the vasculature in PlGF-expressing tumors consisted of relatively large-diameter microvessels with substantial improvement of pericyte coverage. Similarly, PlGF-induced vascular normalization and remodeling were also observed in a spontaneous human choriocarcinoma that expressed endogenous PlGF. Our findings shed light on functions of PlGF as a vascular remodeling factor that normalizes the tumor vasculature and thus may have conceptual implications of cancer therapy.
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PMID:Malignant cell-derived PlGF promotes normalization and remodeling of the tumor vasculature. 1980 67

Targeting angiogenesis in glioblastoma (GBM) may improve patient outcome by normalizing tumor vasculature and improving delivery of chemotherapeutics and oxygen. Consequently, concomitant administration of small molecule inhibitors of the VEGF pathway will likely have a positive impact on chemoradiation treatment outcome. We conducted a Phase I study of vatalanib, a small molecule inhibitor of VEGFR, PDGFR, and c-kit in patients with newly diagnosed GBM receiving radiation, temozolomide, and an enzyme-inducing anti-epileptic drug in order to determine the MTD of vatalanib in this patient population. We incorporated circulating biomarker and SNP analyses and pharmacokinetic studies. Nineteen patients were enrolled and the MTD was not reached at the time of study termination. Vatalanib was well tolerated with only 2 DLTs (thrombocytopenia and elevated transaminases). Other grade 3/4 toxicities included leukopenia, lymphopenia, neutropenia, and hand-foot syndrome. There were no wound-healing complications. Of the 13 patients evaluable for a radiographic response, 2 had a partial response and 9 had stable disease. Vatalanib significantly increased PlGF and sVEGFR1 in plasma circulation and decreased sVEGFR2 and sTie2. Plasma collagen IV increased significantly by day 50 of treatment. Vatalanib was well tolerated and this study demonstrates the safety of oral small molecule inhibitors in newly diagnosed GBM patients. Blood biomarkers may be useful as pharmacodynamic markers of response to anti-angiogenic therapies.
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PMID:Phase I trial with biomarker studies of vatalanib (PTK787) in patients with newly diagnosed glioblastoma treated with enzyme inducing anti-epileptic drugs and standard radiation and temozolomide. 2082 42

Aflibercept, also known as vascular endothelial growth factor (VEGF)-Trap, is a recombinant, decoy receptor fusion protein, rationally designed to block angiogenesis by targeting not only all forms of VEGF-A, but also VEGF-B and placental growth factor. It inhibits VEGF-induced angiogenesis in preclinical models. In tumor models, aflibercept is associated with the reduction of tumor vasculature and size, and the inhibition of ascites formation. Clinical studies are investigating the use of aflibercept alone and in combination with other antineoplastic therapies for the treatment of various cancers. Phase I and II studies have provided proof of principle, and support the continuing clinical investigation of aflibercept. Results from the phase III study, VITAL, of aflibercept in the second-line setting in patients with advanced non-small cell lung cancer [NCT00532155] demonstrated efficacy in progression-free survival and overall objective response rate, but overall survival was not significantly improved. A full report awaits publication. The Phase III VANILLA trial in metastatic pancreatic cancer [NCT00574275] showed no improvement in overall survival. Most recently, the phase III VELOUR study [NCT00561470] of aflibercept plus FOLFIRI compared with placebo plus FOLFIRI in patients with metastatic colorectal cancer following failure of an oxaliplatin regimen showed significant improvements in overall survival, progression-free survival, and response rate and the complete results have been submitted to a peer-reviewed journal. This review summarizes preclinical and clinical data for aflibercept and discusses future directions and clinical trials for this agent.
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PMID:A preclinical and clinical review of aflibercept for the management of cancer. 2226 50

Angiogenesis is the process of formation of new blood vessels due to over expression of VEGF (vascular endothelial growth factor) which plays a critical role in the growth and development of all solid tumor types. With the advancement in understanding of tumor angiogenesis and VEGF, there have been a number of agents developed to target VEGF for the treatment of cancer. These targeted agents can affect downstream VEGF signal transduction by unique mechanisms at different cellular and extracellular levels. FDA has recently approved Aflibercept or VEGF-Trap in August 2012 for the treatment of colorectal cancer. It is a recombinant, decoy receptor fusion protein, rationally designed to block angiogenesis by targeting VEGF-A, VEGF-B and placental growth factor. VEGF-Trap exerts its antiangiogenic effects through regression of tumor vasculature, remodelling or normalization of surviving vasculature and inhibition of new tumor vessel growth. In this review, pre-clinical and clinical data have been summarized for aflibercept alone and in combination with chemotherapy to explore its efficacy and benefits in ovarian cancer, breast cancer, non-small cell lung cancer, pancreatic cancer, glioblastoma, adenocarcinoma and renal cell cancer xenograft models.
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PMID:Aflibercept: a novel VEGF targeted agent to explore the future perspectives of anti-angiogenic therapy for the treatment of multiple tumors. 2331 99

Beyond their ability to inhibit cholesterol biosynthesis, the statins have pleiotropic effects that include anti-inflammatory and immunomodulatory activities. Statins could have clinical utility, alone or in combination with other chemotherapeutics, in the treatment of cancer. The mechanisms that underlie the anti-tumor activity of the statins are nonetheless poorly defined. No studies have analyzed how they alter the tumor-associated leukocyte infiltrate, a central factor that influences tumor stroma and cancer evolution. Here we used HER2/neu transgenic (Tg-neu) mice to analyze the effect of lovastatin (Lov) on the inflammatory reaction of spontaneous mammary tumors. Lov treatment of tumor-bearing Tg-neu mice did not alter growth of established tumors, but significantly reduced the number of new oncogenic lesions in these mice. Moreover, Lov inhibited the growth of newly implanted Tg-neu tumors in immunocompetent but not in immunodeficient mice. We found that Lov enhanced tumor infiltration by effector T cells, and reduced the number of immunosuppressive and pro-angiogenic M2-like tumor-associated macrophages (TAM). Concomitantly, the drug improved the structure and function of the tumor vasculature, measured as enhanced tumor oxygenation and penetration of cytotoxic drugs. Microarray analysis identified a Lov-elicited genetic program in Tg-neu tumors that might explain these effects; we observed Lov-induced downregulation of placental growth factor, which triggers aberrant angiogenesis and M2-like TAM polarization. Our results identify a role for lovastatin in the shaping and re-education of the inflammatory infiltrate in tumors, with functional consequences in angiogenesis and antitumor immunity.
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PMID:A lovastatin-elicited genetic program inhibits M2 macrophage polarization and enhances T cell infiltration into spontaneous mouse mammary tumors. 2431 54

Addition of anti-VEGF antibody therapy to standard chemotherapies has improved survival and is an accepted standard of care for advanced non-small cell lung cancer (NSCLC). However, the mechanisms by which anti-VEGF therapy increases survival remain unclear. We evaluated dynamic CT-based vascular parameters and plasma cytokines after bevacizumab alone and after bevacizumab plus chemotherapy with carboplatin and nab-paclitaxel in advanced NSCLC patients to explore potential biomarkers of treatment response and resistance to this regimen. Thirty-six patients were enrolled in this study. The primary end point was 6-mo progression-free survival rate, which was 74% (95% CI: 57, 97). This regimen has a promising overall response rate of 36% and median time to progression of 8.5 (6.0, 38.7) mo and overall survival of 12.2 (9.6, 44.1) mo. We found that anti-VEGF therapy led to a sustained increase in plasma PlGF, a potential pharmacodynamic marker. We also found that higher levels of soluble VEGFR1 measured before starting bevacizumab with chemotherapy were associated with worse survival, supporting its potential role as biomarker of treatment resistance. Our imaging biomarker studies indicate that bevacizumab-based treatment-while reducing blood flow, volume, and permeability in the overall population-may be associated with improved survival in patients with improved tumor vasculature and blood perfusion after treatment. This hypothesis-generating study supports the notion that excessively decreasing vascular permeability and pruning/rarefaction after bevacizumab therapy may negatively impact the outcome of combination therapy in NSCLC patients. This hypothesis warrants further dose-titration studies of bevacizumab to examine the dose effect on tumor vasculature and treatment efficacy.
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PMID:Improved tumor vascularization after anti-VEGF therapy with carboplatin and nab-paclitaxel associates with survival in lung cancer. 2608 Apr 34

Angiogenesis is the process through which new blood vessels are formed from pre-existing vessels and is essential for the growth of all solid tumors. Vascular endothelial growth factor (VEGF) is a regulator of angiogenesis, which is crucial for tumor growth and metastasis. Its inhibition with antiangiogenic drugs is thought to improve delivery of chemotherapy through vascular normalization and disruption of tumor vasculature. Aflibercept is a recombinant fusion protein of the VEGF receptor (VEGFR)1 and VEGFR2 extracellular domains that binds to VEGF-A, VEGF-B, placental growth factor (PlGF) 1 and 2. Aflibercept has demonstrated preclinical efficacy in different tumor types and exerts its antiangiogenic effects through regression of tumor vasculature, remolding of vasculature, and inhibition of new tumor vessel growth. This review examines the effects of aflibercept on tumor vasculature and on different types of solid tumors, and explores the preclinical and clinical benefits of inclusion aflibercept into anticancer treatment strategies.
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PMID:Aflibercept a new target therapy in cancer treatment: a review. 2622 65


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