VEGF trap as a novel antiangiogenic treatment currently in clinical trials for cancer and eye diseases, and VelociGene- based discovery of the next generation of angiogenesis targets

Production of a biosimilar version of aflibercept to improve VEGF blocker cytotoxicity on endothelial cells

This project aimed to produce a biosimilar version of aflibercept (AFL) and evaluate the effect of the co-treatment of AFL with other vascular endothelial growth factor (VEGF) blocker drugs. For this purpose, the optimized gene was inserted into the pCHO1.0 plasmid and transfected into the CHO-S cell line. The final concentration of biosimilar-AFL for the selected clone was 782 mg/L. Results revealed that the inhibition potential of the biosimilar-AFL on HUVEC cells was significant at 10 and 100 nM concentrations and in a dose-dependent manner. Furthermore, co-treatment of biosimilar-AFL with Everolimus (EVR), Lenvatinib (LEN), and Sorafenib (SOR) could reduce HUVEC cell viability/proliferation, more than when used alone. When LEN and SOR were co-treated with biosimilar-AFL, their cytotoxicity increased 10-fold. The most and least efficient combination was seen when biosimilar-AFL combined with LEN and EVR, respectively. Finally, biosimilar-AFL may improve the efficiency of LEN, EVR, and SOR in reducing the VEGF effect on endothelial cells.

The Novel Pathogenesis of Retinopathy Mediated by Multiple RTK Signals is Uncovered in Newly Developed Mouse Model

Pericyte desorption from retinal blood vessels and subsequent vascular abnormalities are the pathogenesis of diabetic retinopathy (DR). Although the involvement of abnormal signals including platelet-derived growth factor receptor-β (PDGFRβ) and vascular endothelial growth factor-A (VEGF-A) have been hypothesized in DR, the mechanisms that underlie this processes are largely unknown. Here, novel retinopathy mouse model (N-PRβ-KO) was developed with conditional Pdgfrb gene deletion by Nestin promoter-driven Cre recombinase (Nestin-Cre) that consistently reproduced through early non-proliferative to late proliferative DR pathologies. Depletion of Nestin-Cre-sensitive PDGFRβ⁺NG2⁺αSMA⁻ pericytes suppressed pericyte-coverages and induced severe vascular lesion and hemorrhage. Nestin-Cre-insensitive PDGFRβ⁺NG2⁺αSMA⁺ pericytes detached from the vascular wall, and subsequently changed into myofibroblasts in proliferative membrane to cause retinal traction. PDGFRα⁺ astrogliosis was seen in degenerated retina. Expressions of placental growth factor (PlGF), VEGF-A and PDGF-BB were significantly increased in the retina of N-PRβ-KO. PDGF-BB may contribute to the pericyte-fibroblast transition and glial scar formation. Since VEGFR1 signal blockade significantly ameliorated the vascular phenotype in N-PRβ-KO mice, the augmented VEGFR1 signal by PlGF and VEGF-A was indicated to mediate vascular lesions. In addition to PDGF-BB, PlGF and VEGF-A with their intracellular signals may be the relevant therapeutic targets to protect eyes from DR.

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Novel retinopathy mouse model that exhibits proliferative membrane and pathological angiogenesis is successfully generated.

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Cell signalings mediated by PDGF-BB-PDGFRα/PDGFRβ axes are involved in retinal detachment.

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Cell signaling mediated by PlGF/VEGF-A-VEGFR1 axis is involved in pathological angiogenesis.

Diabetic retinopathy (DR) is a major cause of vision impairment worldwide. We newly developed retinopathy mouse model (N-PRβ-KO) with conditional Pdgfrb gene deletion by Nestin promoter-driven Cre recombinase consistently reproduced through early non-proliferative to late proliferative DR pathologies. Through the present study utilizing N-PRβ-KO mice, novel pathogenesis of retinopathy was uncovered, in which PDGFRα and PDGFRβ activated by increased PDGF-BB were indicated to be involved in astrogliosis and the formation of proliferative membrane, and VEGFR1 activated by increased PlGF and VEGF-A was indicated to be involved in pathological angiogenesis. These signals may be the relevant therapeutic targets for DR.

Angiogenic cytokines and their influence on circulating tumour cells in sera of patients with the primary diagnosis of breast cancer before treatment

Background

Circulating tumour cells (CTCs) have been found to be a prognostic marker for reduced disease free survival, breast cancer–specific survival, and overall survival before the start of systemic treatment.

Methods

A total of 200 patients’ sera were included in this study, 100 patients being CTC positive and 100 patients being CTC negative. Matching criteria were histo-pathological grading, lymph node metastasis, hormone receptor status, TNM classification and survived breast cancer patients vs. deceased tumor associated patients. A multi cytokine/chemokine array was used to screen the sera for the angiogenic markers.

Results

Statistical significant correlation was exposed for sFlt1 values in regard to the CTC-Status. CTC negative patients displayed increased sFlt1 expression opposed to CTC positive breast cancer patients. Furthermore, significant enhanced PIGF values were also disclosed in CTC negative patients compared to patients being CTC positive. Analyzing the living patient collective we found significant differences in sFlt1 and PlGF values in regard to CTC negative and CTC positive patients.

Conclusion

Both vascular markers showed enhanced expression in the CTC negative patient collective. To continue, the collective graded G2 showed significantly enhanced sFlt1 expressions amongst patients with no CTCs. Moreover, the patient collective with no lymph node metastasis and CTC negativity indicated statistically significant increased sFlt1 values. A functional interaction of sFlt1 and PlGF was found, suggesting that their overexpression in tumour cells inhibits CTCs entering the peripheral blood. Furthermore, in regard to CTC negativity, sFlt1 and PlGF values may potentially serve as predictive markers.

Trial registration

The TRN of this study is NCT02181101 and the date of registration was the 4^th of June 2014. The study was retrospectively registered.

Resistance to Anti-VEGF Therapy Mediated by Autocrine IL6/STAT3 Signaling and Overcome by IL6 Blockade

Anti-VEGF therapies benefit several cancer types, but drug resistance that limits therapeutic response can emerge. We generated cell lines from anti-VEGF-resistant tumor xenografts to investigate the mechanisms by which resistance develops. Of all tumor cells tested, only A431 (A431-V) epidermoid carcinoma cells developed partial resistance to the VEGF inhibitor aflibercept. Compared with the parental tumors, A431-V tumors secreted greater amounts of IL6 and exhibited higher levels of phospho-STAT3. Notably, combined blockade of IL6 receptor (IL6R) and VEGF resulted in enhanced activity against A431-V tumors. Similarly, inhibition of IL6R enhanced the antitumor effects of aflibercept in DU145 prostate tumor cells that displays high endogenous IL6R activity. In addition, post hoc stratification of data obtained from a clinical trial investigating aflibercept efficacy in ovarian cancer showed poorer survival in patients with high levels of circulating IL6. These results suggest that the activation of the IL6/STAT3 pathway in tumor cells may provide a survival advantage during anti-VEGF treatment, suggesting its utility as a source of response biomarkers and as a therapeutic target to heighten efficacious results. Cancer Res; 76(8); 2327-39. ©2016 AACR.

Novel Small Molecule Inhibitors of Cancer Stem Cell Signaling Pathways

The main aim of oncologists worldwide is to understand and then intervene in the primary tumor initiation and propagation mechanisms. This is essential to allow targeted elimination of cancer cells without altering normal mitotic cells. Currently, there are two main rival theories describing the process of tumorigenesis. According to the Stochastic Model, potentially any cell, once defunct, is capable of initiating carcinogenesis. Alternatively the Cancer Stem Cell (CSC) Model posits that only a small fraction of undifferentiated tumor cells are capable of triggering carcinogenesis. Like healthy stem cells, CSCs are also characterized by a capacity for self-renewal and the ability to generate differentiated progeny, possibly mediating treatment resistance, thus leading to tumor recurrence and metastasis. Moreover, molecular signaling profiles are similar between CSCs and normal stem cells, including Wnt, Notch and Hedgehog pathways. Therefore, development of novel chemotherapeutic agents and proteins (e.g., enzymes and antibodies) specifically targeting CSCs are attractive pharmaceutical candidates. This article describes small molecule inhibitors of stem cell pathways Wnt, Notch and Hedgehog, and their recent chemotherapy clinical trials.

Vascular endothelial growth factor trap-eye and trap technology: Aflibercept from bench to bedside

Anti-vascular endothelial growth factor (VEGF) currently used to treat eye diseases have included monoclonal antibodies, antibody fragments, and an aptamer. A different method of achieving VEGF blockade in retinal diseases includes the concept of a cytokine trap. Cytokine traps technology are being evaluated for the treatment of various diseases that are driven by excessive cytokine levels. Traps consist of two extracellular cytokine receptor domains fused together to form a human immunoglobulin G (IgG). Aflibercept/VEGF trap-eye (VTE) is a soluble fusion protein, which combines ligand-binding elements taken from the extracellular components of VEGF receptors 1 and 2 fused to the Fc portion of IgG. This protein contains all human amino acid sequences, which minimizes the potential for immunogenicity in human patients. This review presents the latest data on VTE in regard to the pharmacokinetics, dosage and safety, preclinical and clinical experiences. Method of the literature search: A systematic search of the literature was conducted on PubMed, Scopus, and Google Scholar with no limitation on language or year of publication databases. It was oriented to articles published for VTE in preclinical and clinical studies and was focused on the pharmacokinetics, dosage and safety of VTE.

[New targeted therapies in breast cancer]

Trastuzumab improves care of patients with HER2+ breast cancer and allows a major gain in terms of survival. T-DM1 and pertuzumab are two new treatments, which give very encouraging results in metastatic breast cancer. Their place in neo-adjuvant and adjuvant setting still remains to be defined. Bevacizumab have its place in metastatic breast cancer. In adjuvant setting, results are disappointing and in neo-adjuvant setting, we need more studies on subgroups, which can benefit more. Development of the PARP inhibitors was slowed down by recent negative results in metastatic breast cancer but studies continue with more targeted patient's. Finally, everolimus, inhibitor of mTOR, allows to by pass the hormono-resistance in metastatic phase. Its toxicity must be taken into account in particular in adjuvant setting.

Decursin inhibited proliferation and angiogenesis of endothelial cells to suppress diabetic retinopathy via VEGFR2

Diabetes induces pathologic proliferation and angiogenesis in the retina that leads to catastrophic loss of vision. Decursin is a novel therapeutic that targets the vascular endothelial growth factor (VEGF) receptor (VEGFR) with putative anti-proliferative and anti-angiogenic activities. Thereby we utilized human retinal microvascular endothelial cells (HRMEC) and human umbilical vein endothelial cells (HUVEC) under conditions of excess glucose to explore dose-dependent responses of decursin on markers of migration, angiogenesis, and proliferation. Decursin dose-dependently inhibited tube formation, VEGFR-2 expression, along with relative metabolic activity and 5-bromo-2'-deoxy-uridine (BrdU) activity in both cell lines. We then correlated our findings to the streptozotocin-induced rat model of diabetes. Following three months of decursin treatment VEGFR-2 expression was significantly inhibited. Our data would suggest that decursin may be a potent anti-angiogenic and anti-proliferative agent targeting the VEGFR-2 signaling pathway, which significantly inhibits diabetic retinal neovascularization.

Importance of social support in cancer patients

Social support is regarded as a complex construct which has long been suggested to have direct and buffering effects on patients' wellbeing and emotional adjustment to cancer. Cross-sectional and prospective studies show a positive association between perceived social support and psychological adjustment following cancer treatment. Research findings suggest that the evidence for the relationship between social support and cancer progression is sufficiently strong. This report points out the importance of social support in cancer and provides recommendations for health care professionals.

Sustained production of a soluble IGF-I receptor by gutless adenovirus-transduced host cells protects from tumor growth in the liver

The IGF-I receptor (IGF-IR) has an important role in malignant disease and is the target of several drugs presently in clinical trials. Gene therapy has been explored as cancer treatment, mainly for delivery of genes that induce cell death or enhance the immunological response to cancer. Previously, we have shown that the implantation of autologous bone-marrow stromal cells producing a soluble form of IGF-IR (sIGFIR) inhibited experimental liver metastasis of several tumor types in mice. Here, we evaluated the utility of adenovirus-based gene delivery for generating therapeutically effective plasma levels of this decoy. We constructed a third generation gutless adenovirus expressing sIGFIR and found that HEK-293 cells transduced by this, but not control adenoviruses, secreted soluble receptor protein that blocked IGF-I-induced tumor cell migration, proliferation and survival in vitro. Following virus injection in vivo, viral DNA was detectable by PCR in several host organs, particularly the liver, and this resulted in the production of measurable sIGFIR plasma levels for up to 21 days post injection. In mice producing virus-encoded sIGFIR, experimental liver metastasis was inhibited, indicating that sIGFIR levels were therapeutically effective. The results show that adenovirus-based delivery of inhibitory soluble proteins can provide an effective anticancer strategy.

VEGF and Notch in tip and stalk cell selection

Sprouting angiogenesis is a dynamic process in which endothelial cells collectively migrate, shape new lumenized tubes, make new connections, and remodel the nascent network into a hierarchically branched and functionally perfused vascular bed. Endothelial cells in the nascent sprout adopt two distinct cellular phenotypes--known as tip and stalk cells--with specialized functions and gene expression patterns. VEGF and Notch signaling engage in an intricate cross talk to balance tip and stalk cell formation and to regulate directed tip cell migration and stalk cell proliferation. In this article, we summarize the current knowledge and implications of the tip/stalk cell concepts and the quantitative and dynamic integration of VEGF and Notch signaling in tip and stalk cell selection.

Relationship between loneliness and proangiogenic cytokines in newly diagnosed tumors of colon and rectum

OBJECTIVE

To investigate the association of serum levels of proangiogenic cytokines with different indices of social support and loneliness by measuring the levels of expression of two important proangiogenic cytokines, vascular endothelial growth factor (VEGF), and interleukin-6 in tumors of colon and rectum. Lack of social support has been prospectively associated with cancer progression.

METHODS

Fifty-one newly diagnosed patients with colorectal tumors (mean age, 68.3 years) completed two measures of loneliness 1 to 2 days before their surgical treatment. The first was an explicit self-report questionnaire, which tapped into negative feelings as a result of low social support. The second was a standardized computer-based task, which measured loneliness implicitly. Immunohistochemical analyses were performed on tumor tissues post surgery to determine the expression of cytokines.

RESULTS

Logistic regression showed that higher levels of implicit loneliness independently predicted stronger expression of VEGF, controlling for Dukes stage and explicit loneliness, both of which were nonsignificant predictors. No significant relationships were found between the loneliness measures and interleukin-6.

CONCLUSIONS

The results of this study suggest VEGF to be an angiogenic mechanism through which loneliness may lead to worse cancer-related outcomes. Implications are discussed in terms of devising targeted psychosocial and immunotherapeutic interventions for cancer patients with low social support.

Social support and cancer progression: a systematic review

OBJECTIVE

The variability in the conceptualization and categorization of social support has resulted in mixed findings regarding its role in cancer progression. This systematic review identifies and summarizes the evidence for the significance of two important indices of social support in progression of different cancers.

METHOD

We used systematic and replicable methods to search, select, and evaluate findings.

RESULTS

Thirty-one longitudinal prospective findings (in 26 papers) which were selected for inclusion categorized social support into structural and functional support. The types of cancer included in these studies fell into three major categories: breast cancer (16), other cancer (10), and mixed cancers (5). Results suggest that the evidence for the relationship between social support and cancer progression is sufficiently strong for breast cancer as shown by five out of seven methodologically sound studies but consistently unconvincing for other types of cancer or in studies which combined different types of cancer. Structural support indices were found to be more frequently associated with disease progression than the indices of functional support in breast cancer. Disease-related variables such as severity, treatment, nodal status, and site of metastasis were found to be significant predictors of cancer progression, and it is suggested that these variables must be considered when conducting studies on the role of psychosocial factors in cancer-related outcomes including progression.

CONCLUSION

Methodological limitations of the studies and counterintuitive findings are discussed, and further conclusive research, particularly randomized controlled trials of social support interventions, is warranted to support the findings of this systematic review.

Magnetic resonance imaging defines cervicovaginal anatomy, cancer, and VEGF trap antiangiogenic efficacy in estrogen-treated K14-HPV16 transgenic mice

Noninvasive detection of dysplasia provides a potential platform for monitoring the efficacy of chemopreventive therapy of premalignancy, imaging the tissue compartments comprising dysplasia: epithelium, microvasculature, and stromal inflammatory cells. Here, using respiratory-gated magnetic resonance imaging (MRI), the anatomy of premalignant and malignant stages of cervical carcinogenesis in estrogen-treated K14-HPV16 transgenic mice was noninvasively defined. Dynamic contrast enhanced (DCE)-MRI was used to quantify leakage across premalignant dysplastic microvasculature. Vascular permeability as measured by DCE-MRI, K(trans), was similar in transgenic (0.053 +/- 0.020 min(-1); n = 32 mice) and nontransgenic (0.056 +/- 0.029 min(-1); n = 17 mice) animals despite a 2-fold increase in microvascular area in the former compared with the latter. DCE-MRI did detect a significant decrease in vascular permeability accompanying diminution of dysplastic microvasculature by the antiangiogenic agent, vascular endothelial growth factor Trap (K(trans) = 0.052 +/- 0.013 min(-1) pretreatment; n = 6 mice versus K(trans) = 0.019 +/- 0.008 min(-1) post-treatment; n = 5 mice). Thus, we determined that the threshold of microvessel leakage associated with cervical dysplasia was <17 kDa and highlighted the potential of DCE-MRI to noninvasively monitor the efficacy of antiangiogenic drugs or chemoprevention regimens targeting the vasculature in premalignant cervical dysplasia.

Human interleukin 10 receptor 1/IgG1-Fc fusion proteins: immunoadhesins for human IL-10 with therapeutic potential

Interleukin 10 (IL-10) is produced by various types of human cancer, including malignant melanoma, and plays an important role in negative regulation of cell-mediated immune responses against tumors. We have developed chimeric molecules (immunoadhesins), combining the extracellular domain of human interleukin 10 receptor 1 (IL-10R1) with the Fc regions of human IgG1 heavy chain and investigated their capability of blocking the biological activities of human IL-10. Monomeric and dimeric immunoadhesins (IL-10R1/IgG1) constructs were tested for capturing human IL-10 and blocking its biological activities. Plasmid vectors that contained the IL-10 immunoadhesin constructs were directly transfected into human melanoma cell lines. Transfection of plasmid vectors into melanoma cell lines resulted in capturing of exogenously added as well as endogeneously produced IL-10. The supernatants obtained from an IL-10 non-producing melanoma cell line transfected with monomeric IL-10 immunoadhesin plasmids most efficiently captured exogenously added IL-10, compared to those obtained with the dimeric IL-10R1/IgG1 plasmid vector. Transfection of IL-10-producing melanoma cells with the monomeric IL-10 immunoadhesin plasmids totally captured endogenously produced IL-10 and enhanced T cell responses against allogeneic melanoma cells. Furthermore, purified monomeric IL-10 immunoadhesin protein showed IL-10 capturing efficacy compatible with that of IL-10-specific monoclonal antibodies. Collectively, these studies indicate that IL-10 immunoadhesins, especially in monomeric form, are potent inhibitors of biological activities of IL-10 and suggest that these molecules, alone or in conjunctions with other immunotherapeutic approaches, can be utilized for the immuno-targeting of IL-10 producing tumors.

Hypertension and proteinuria: a class-effect of antiangiogenic therapies

Antiangiogenic therapy has now become a cornerstone in the treatment of several solid tumor cancers. Those drugs present with a renal toxicity profile manifesting as proteinuria and hypertension, often reported in the literature to be linked to bevacizumab, a monoclonal antibody targeted at the circulating vascular endothelial growth factor (VEGF). However, there is evidence that those side effects are most probably related to the pharmacological action of those drugs: the inhibition of the VEGF pathway. Thus, they may occur with any antiangiogenic therapy, either those acting on circulating VEGF (bevacizumab or VEGF-trap), or those acting on VEGF receptor(s) (sunitinib, sorafenib, or axitinib). Clinicians should thus be aware of such a 'class effect' to appropriately monitor and treat their patients, regardless of which antiangiogenic drug is used.

Neutralizing endogenous VEGF following traumatic spinal cord injury modulates microvascular plasticity but not tissue sparing or functional recovery

Acute loss of spinal cord vascularity followed by an endogenous adaptive angiogenic response with concomitant microvascular dysfunction is a hallmark of traumatic spinal cord injury (SCI). Recently, the potent vasoactive factor vascular endothelial growth factor (VEGF) has received much attention as a putative therapeutic for the treatment of various neurodegenerative disorders, including SCI. Exogenous VEGF exerts both protective and destabilizing effects on microvascular elements and tissue following SCI but the role of endogenous VEGF is unclear. In the present study, we systemically applied a potent and well characterized soluble VEGF antagonist to adult C57Bl/6 mice post-SCI to elucidate the relative contribution of VEGF on the acute evolving microvascular response and its impact on functional recovery. While the VEGF Trap did not alter vascular density in the injury epicenter or penumbra, an overall increase in the number of Griffonia simplicifolia isolectin-B4 bound microvessels was observed, suggesting a VEGF-dependency to more subtle aspects of endothelial plasticity post-SCI. Neutralizing endogenous VEGF neither attenuated nor exacerbated chronic histopathology or functional recovery. These results support the idea that overall, endogenous VEGF is not neuroprotective or detrimental following traumatic SCI. Furthermore, they suggest that angiogenesis in traumatically injured spinal tissue is regulated by multiple effectors and is not limited by endogenous VEGF activation of affected spinal microvessels.

M-CSF inhibition selectively targets pathological angiogenesis and lymphangiogenesis

Antiangiogenic therapy for the treatment of cancer and other neovascular diseases is desired to be selective for pathological angiogenesis and lymphangiogenesis. Macrophage colony-stimulating factor (M-CSF), a cytokine required for the differentiation of monocyte lineage cells, promotes the formation of high-density vessel networks in tumors and therefore possesses therapeutic potential as an M-CSF inhibitor. However, the physiological role of M-CSF in vascular and lymphatic development, as well as the precise mechanisms underlying the antiangiogenic effects of M-CSF inhibition, remains unclear. Moreover, therapeutic potential of M-CSF inhibition in other neovascular diseases has not yet been evaluated. We used osteopetrotic (op/op) mice to demonstrate that M-CSF deficiency reduces the abundance of LYVE-1⁺ and LYVE1⁻ macrophages, resulting in defects in vascular and lymphatic development. In ischemic retinopathy, M-CSF was required for pathological neovascularization but was not required for the recovery of normal vasculature. In mouse osteosarcoma, M-CSF inhibition effectively suppressed tumor angiogenesis and lymphangiogenesis, and it disorganized extracellular matrices. In contrast to VEGF blockade, interruption of M-CSF inhibition did not promote rapid vascular regrowth. Continuous M-CSF inhibition did not affect healthy vascular and lymphatic systems outside tumors. These results suggest that M-CSF–targeted therapy is an ideal strategy for treating ocular neovascular diseases and cancer.

Autologous bone marrow stromal cells genetically engineered to secrete an igf-I receptor decoy prevent the growth of liver metastases

Liver metastases respond poorly to current therapy and remain a frequent cause of cancer-related mortality. We reported previously that tumor cells expressing a soluble form of the insulin-like growth factor-I receptor (sIGFIR) lost the ability to metastasize to the liver. Here, we sought to develop a novel therapeutic approach for prevention of hepatic metastasis based on sustained in vivo delivery of the soluble receptor by genetically engineered autologous bone marrow stromal cells. We found that when implanted into mice, these cells secreted high plasma levels of sIGFIR and inhibited experimental hepatic metastases of colon and lung carcinoma cells. In hepatic micrometastases, a reduction in intralesional angiogenesis and increased tumor cell apoptosis were observed. The results show that the soluble receptor acted as a decoy to abort insulin-like growth factor-I receptor (IGF-IR) functions during the early stages of metastasis and identify sustained sIGFIR delivery by cell-based vehicles as a potential approach for prevention of hepatic metastasis.

Specific blockade of VEGF and HER2 pathways results in greater growth inhibition of breast cancer xenografts that overexpress HER2

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.

Inhibition of chronic and acute skin inflammation by treatment with a vascular endothelial growth factor receptor tyrosine kinase inhibitor

Although vascular remodeling is a hallmark of many chronic inflammatory disorders, antivascular strategies to treat these conditions have received little attention to date. We investigated the effects of a newly identified vascular endothelial growth factor (VEGF) receptor tyrosine-kinase inhibitor, NVP-BAW2881, on endothelial cell function in vitro and its anti-inflammatory activity in different animal models. NVP-BAW2881 inhibited proliferation, migration, and tube formation by human umbilical vein endothelial cells and lymphatic endothelial cells in vitro. In a transgenic mouse model of psoriasis, NVP-BAW2881 reduced the number of blood and lymphatic vessels and infiltrating leukocytes in the skin, and normalized the epidermal architecture. NVP-BAW2881 also displayed strong anti-inflammatory effects in models of acute inflammation; pretreatment with topical NVP-BAW2881 significantly inhibited VEGF-A-induced vascular permeability in the skin of pigs and mice. Furthermore, topical application of NVP-BAW2881 reduced the inflammatory response elicited in pig skin by UV-B irradiation or by contact hypersensitivity reactions. These results demonstrate for the first time that VEGF receptor tyrosine-kinase inhibitors might be used to treat patients with inflammatory skin disorders such as psoriasis.

Angiogenesis in melanoma

The process of angiogenesis is crucial for progression and metastasis of the majority of solid tumors including melanomas. The current review summarizes existing knowledge of the mechanisms of angiogenesis in melanoma, as well as current anti-angiogenic therapeutic strategies and their targets. We focus primarily on the role of key growth factors that are secreted by melanoma cells and known to trigger angiogenic responses, and their receptors as expressed on both endothelial and melanoma cells. Many of these growth factors function in synergy with receptors for extracellular matrix, integrins, and matrix metalloproteinases (MMPs). All of these systems of molecules are activated during major stages of angiogenesis such as endothelial migration, proliferation, and reorganization of surrounding extracellular matrix. The blockade of these molecules and their downstream pathways leads to inhibition of melanoma vascularization. Thus, these classes of molecules are essential for melanoma angiogenesis and, therefore, might serve as promising targets for therapeutic intervention. Many recently developed compounds targeting key pathways in angiogenesis are in their final stages of clinical trials.

VEGF Trap complex formation measures production rates of VEGF, providing a biomarker for predicting efficacious angiogenic blockade

VEGF is the best characterized mediator of tumor angiogenesis. Anti-VEGF agents have recently demonstrated impressive efficacy in human cancer trials, but the optimal dosing of such agents must still be determined empirically, because biomarkers to guide dosing have yet to be established. The widely accepted (but unverified) assumption that VEGF production is quite low in normal adults led to the notion that increased systemic VEGF levels might quantitatively reflect tumor mass and angiogenic activity. We describe an approach to determine host and tumor production of VEGF, using a high-affinity and long-lived VEGF antagonist now in clinical trials, the VEGF Trap. Unlike antibody complexes that are usually rapidly cleared, the VEGF Trap forms inert complexes with tissue- and tumor-derived VEGF that remain stably in the systemic circulation, where they are readily assayable, providing unprecedented capability to accurately measure VEGF production. We report that VEGF production is surprisingly high in non-tumor-bearing rodents and humans, challenging the notion that systemic VEGF levels can serve as a sensitive surrogate for tumor load; tumor VEGF contribution becomes significant only with very large tumor loads. These findings have the important corollary that anti-VEGF therapies must be sufficiently dosed to avoid diversion by host-derived VEGF. We further show that our assay can indicate when VEGF is optimally blocked; such biomarkers to guide dosing do not exist for other anti-VEGF agents. Based on this assay, VEGF Trap doses currently being assessed in clinical trials are in the efficacious range.

The molecules: mechanisms of arterial vasodilatation observed in the splanchnic and systemic circulation in portal hypertension

A hyperdynamic splanchnic and systemic circulation is typical of cirrhotic patients and has been observed in all experimental forms of portal hypertension. The hyperdynamic circulation is most likely initiated by arterial vasodilatation, leading to central hypovolemia, sodium retention, and an increased intravascular volume. Arterial vasodilatation is regulated by a complex interplay of various vasodilator molecules and factors that influence the production of those vasodilator molecules. Nitric oxide (NO) has been recognized as the most important vasodilator molecule that mediates the excessive arterial vasodilatation observed in portal hypertension. The aims of this review are (1) to categorize NO synthase isoforms involved in NO overproduction; (2) to explain the mechanisms of endothelial NO synthase up-regulation; and (3) to summarize other molecules involved in the arterial vasodilatation.

Vascular endothelial dysfunction in cirrhosis

Endothelial dysfunction is regarded as an early key event in multiple diseases. The assessment of vascular nitric oxide (NO) level is an indicative of endothelial dysfunction. In liver cirrhosis, on one hand, endothelial dysfunction is known as impaired endothelium-dependent relaxation in the liver microcirculation and contributes to increased intra-hepatic vascular resistance, leading to portal hypertension. On the other, increased production of vasodilator molecules mainly NO contributes to increased endothelium-dependent relaxation in the arteries of the systemic and splanchnic circulation. The aims of this review are to summarize and discuss: (1) unique characteristics of sinusoidal endothelial cell (SECs) and SEC dysfunctions in cirrhosis, and (2) endothelial dysfunctions in the arterial splanchnic and systemic circulation in cirrhosis with portal hypertension.

The Delta paradox: DLL4 blockade leads to more tumour vessels but less tumour growth

Anti-angiogenesis therapies have emerged as important treatment options for several types of tumours. To date, these therapies have focused on blocking the vascular endothelial growth factor (VEGF) pathway. A recent series of papers have shown that one ligand for the Notch receptors, Delta-like ligand 4 (DLL4), is normally induced by VEGF and is a negative-feedback regulator that restrains vascular sprouting and branching. Consistent with this role, the deletion or inhibition of DLL4 results in excessive, non-productive angiogenesis. This unrestrained angiogenesis unexpectedly and paradoxically decreases tumour growth, even in tumours resistant to anti-VEGF therapies. Can too much angiogenesis be bad for tumours but good for patients?

Blockade of Dll4 inhibits tumour growth by promoting non-productive angiogenesis

Tumour growth requires accompanying expansion of the host vasculature, with tumour progression often correlated with vascular density. Vascular endothelial growth factor (VEGF) is the best-characterized inducer of tumour angiogenesis. We report that VEGF dynamically regulates tumour endothelial expression of Delta-like ligand 4 (Dll4), which was previously shown to be absolutely required for normal embryonic vascular development. To define Dll4 function in tumour angiogenesis, we manipulated this pathway in murine tumour models using several approaches. Here we show that blockade resulted in markedly increased tumour vascularity, associated with enhanced angiogenic sprouting and branching. Paradoxically, this increased vascularity was non-productive-as shown by poor perfusion and increased hypoxia, and most importantly, by decreased tumour growth-even for tumours resistant to anti-VEGF therapy. Thus, VEGF-induced Dll4 acts as a negative regulator of tumour angiogenesis; its blockade results in a striking uncoupling of tumour growth from vessel density, presenting a novel therapeutic approach even for tumours resistant to anti-VEGF therapies.