Vascular Endothelial Growth Factor A Blockade Research Articles

Abstract 3847: Dual targeting of EGFL6 and VEGF-A to overcome immune suppression in ovarian cancer

Abstract Background: Ovarian carcinomas are known to have a high degree of immune suppression, which may be related, in part, to high levels of vascular endothelial growth factor-A (VEGF-A). Bevacizumab (anti-VEGF antibody) has been shown to increase infiltration of T-cells in the tumor microenvironment (TME). We have also identified EGFL6 as an important angiogenic protein. Here, we examined the biological effects of blocking EGFL6 and VEGF-A in ovarian cancer models. Methods: We studied the in vitro (endothelial tube formation and migration assays) and in vivo (ID8KO-Trp53;Brca2 and SKOV3-ip1 models) biological effects of EGFL6 and VEGF-A blockade. Tumor-infiltrating immune cells were studied by flow cytometry and immunohistochemistry staining. Results: Blocking EGFL6 and VEGF-A simultaneously with monoclonal antibodies in RF24 endothelial cells decreased tube formation and migration significantly, in comparison to VEGF-A blockade alone (p<0.001). EGFL6 monotherapy in ID8KO-Trp53;Brca2 tumor bearing syngeneic mice decreased tumor burden (~2.5 fold, p<0.0001) and increased the infiltration of IFNγ+ (~2.75 fold, p<0.0001) and GzmB+ (~1.75 fold, p<0.01) CD8+ T-cells and IFNγ+ (~2 fold, p<0.0001) and GzmB+ (~2 fold, p<0.01) CD4+ T-cells while decreasing PD-L1+ cells (~1.8 fold, p=0.01). Dual blockade of EGFL6 and VEGF-A in SKOV3-ip1 tumor bearing nude mice significantly decreased tumor burden (~3.72 fold, p<0.01) and angiogenesis (~2.36 fold, p<0.05) compared to controls and single-agent blockade. Similar blockade in ID8KO-Trp53;Brca2 tumor bearing mice significantly decreased tumor burden (~4.2 fold, p=0.0004), improved CD8+ (~3.32 fold, p=0.0004) and CD4+ (~2.81 fold, p<0.0001) T-cell infiltration, NK cell infiltration (~2.3 fold, p=0.0005) and decreased myeloid-derived suppressor cells (MDSCs) (~1.92 fold, p=0.0278) compared to EGFL6 and VEGF-A blockade alone. Conclusions: Our results demonstrate that simultaneously targeting the angiogenesis drivers EGFL6 and VEGF-A in ovarian cancer significantly decreased tumor burden in vivo and increased the infiltration of T lymphocytes compared to single-agent blockade. AACR Category: Tumor Microenvironment and Immune Oncology Key words: ovarian cancer, immune suppression, angiogenesis, VEGF-A, EGFL6 Citation Format: Sujanitha Umamaheswaran, Lingegowda S. Mangala, Robiya Joseph, Nicholas B. Jennings, Mark S. Kim, Yunfei Wen, Emine Bayraktar, Ningyan Zhang, Zhiqiang An, Anil K. Sood. Dual targeting of EGFL6 and VEGF-A to overcome immune suppression in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3847.

ANGI-03. PHARMACOLOGICAL TARGETING OF APELIN/APLNR SIGNALING BLUNTS THERAPY RESISTANCE TO VEGFA/VEGFR2 ANTI-ANGIOGENIC TREATMENT IN GLIOBLASTOMA

Abstract Anti-angiogenic therapy of glioblastoma with bevacizumab, a vascular endothelial growth factor-A (VEGFA) blocking antibody, may accelerate tumor cell invasion and induce alternative angiogenic pathways. We investigated the roles of the pro-angiogenic receptor APLNR and its cognate ligand apelin in VEGFA/VEGFR2 anti-angiogenic therapy against distinct subtypes of glioblastoma. In proneural glioblastoma, apelin levels were downregulated by VEGFA or VEGFR2 blockade by use of bevacizumab or ramucirumab, respectively. A central role for apelin/APLNR in controlling glioblastoma vascularization was corroborated in a serial implantation model of the angiogenic switch that occurs in human glioblastoma. Apelin and APLNR are broadly expressed in human glioblastoma, and knockdown or knockout of APLN in orthotopic models of proneural or classical glioblastoma subtypes massively reduced glioblastoma vascularization as compared with controls. What is more, direct infusion of the bioactive peptide apelin-13 was able to rescue this vascular loss-of-function phenotype, demonstrating the specific control of tumor vascularization by apelin/APLNR signaling. While high levels of apelin correlated with reduced tumor cell invasiveness, the reduction in apelin expression led to accelerated glioblastoma cell invasion. Analysis of stereotactic glioblastoma biopsies from patients as well as from in vitro and in vivo experiments revealed increased dissemination of APLNR-positive tumor cells when apelin levels were reduced. Most interestingly, application of apelin-F13A, a mutant APLNR ligand, blocked both tumor angiogenesis and glioblastoma cell invasion. Furthermore, co-targeting VEGFR2 and APLNR synergistically improved survival of mice bearing proneural glioblastoma. In summary, we show that apelin/APLNR signaling controls glioblastoma angiogenesis and invasion directly, and that both pathological features are blunted by apelin-F13A. We suggest that apelin-F13A can improve the efficiency and reduce the side effects of established anti-angiogenic treatments for distinct glioblastoma subtypes.

Local VEGF-A blockade modulates the microenvironment of the corneal graft bed.

The microenvironment plays an important role in several immunological processes. Vascular endothelial growth factor-A (VEGF-A) not only regulates angiogenesis, but is known as a modulator of the immune microenvironment. Modulating the site of transplantation might be beneficial for subsequent transplant survival. In this study, we therefore analyzed the effect that a local blockade of VEGF-A in the inflamed cornea as the graft receiving tissue has on the immune system. We used the murine model of suture-induced neovascularization and subsequent high-risk corneal transplantation, which is an optimal model for local drug application. Mice were treated with VEGFR1/R2 trap prior to transplantation. We analyzed corneal gene expression, as well as protein levels in the cornea and serum on the day of transplantation, 2 and 8weeks later. Local VEGF depletion prior to transplantation increases the expression of pro-inflammatory as well as immune regulatory cytokines only in the corneal microenvironment, but not in the serum. Furthermore, local VEGFR1/R2 trap treatment significantly inhibits the infiltration of CD11c+ dendritic cells into the cornea. Subsequent increased corneal transplantation success was accompanied by a local upregulation of Foxp3 gene expression. This study demonstrates that locally restricted VEGF depletion increases transplantation success by modulating the receiving corneal microenvironment and inducing tolerogenic mechanisms.

Periostin Limits Tumor Response to VEGFA Inhibition

Resistance to antiangiogenic drugs limits their applicability in cancer therapy. Here, we show that revascularization and progression of pancreatic neuroendocrine tumors (PNETs) under extended vascular-endothelial growth factor A (VEGFA) blockade are dependent on periostin (POSTN), a matricellular protein expressed by stromal cells. Genetic deletion of Postn in RIP1-Tag2 mice blunted tumor rebounds of M2-like macrophages and αSMA+ stromal cells in response to prolonged VEGFA inhibition and suppressed PNET revascularization and progression on therapy. POSTN deficiency also impeded the upregulation of basic fibroblast growth factor (FGF2), an adaptive mechanism previously implicated in PNET evasion from antiangiogenic therapy. Higher POSTN expression correlated with markers of M2-like macrophages in human PNETs, and depleting macrophages with a colony-stimulating factor 1 receptor (CSF1R) antibody inhibited PNET revascularization and progression under VEGFA blockade despite continued POSTN production. These findings suggest a role for POSTN in orchestrating resistance to anti-VEGFA therapy in PNETs.

Dual angiopoietin-2 and VEGFA inhibition elicits antitumor immunity that is enhanced by PD-1 checkpoint blockade.

Pathological angiogenesis is a hallmark of cancer and a therapeutic target. Vascular endothelial growth factor A (VEGFA) and angiopoietin-2 (ANGPT2; also known as ANG2) are proangiogenic cytokines that sustain tumor angiogenesis and limit antitumor immunity. We show that combined ANGPT2 and VEGFA blockade by a bispecific antibody (A2V) provided superior therapeutic benefits, as compared to the single agents, in both genetically engineered and transplant tumor models, including metastatic breast cancer (MMTV-PyMT), pancreatic neuroendocrine tumor (RIP1-Tag2), and melanoma. Mechanistically, A2V promoted vascular regression, tumor necrosis, and antigen presentation by intratumoral phagocytes. A2V also normalized the remaining blood vessels and facilitated the extravasation and perivascular accumulation of activated, interferon-γ (IFNγ)-expressing CD8+ cytotoxic T lymphocytes (CTLs). Whereas the antitumoral activity of A2V was, at least partly, CTL-dependent, perivascular T cells concurrently up-regulated the expression of the immune checkpoint ligand programmed cell death ligand 1 (PD-L1) in tumor endothelial cells. IFNγ neutralization blunted this adaptive response, and PD-1 blockade improved tumor control by A2V in different cancer models. These findings position immune cells as key effectors of antiangiogenic therapy and support the rationale for cotargeting angiogenesis and immune checkpoints in cancer therapy.

VEGF-A is increased in exogenous endophthalmitis

ObjectiveExogenous endophthalmitis is an ophthalmologic emergency defined by panocular inflammation. Vascular endothelial growth factor A (VEGF-A) contributes to inflammation by promoting chemotaxis of monocytes and granulocytes and by increasing vascular permeability. The purpose of this article is to determine if VEGF-A is elevated in the vitreous samples obtained from individuals with exogenous endophthalmitis. MethodsVitreous samples from individuals with exogenous endophthalmitis (n = 18) were analyzed via Luminex assay and enzyme-linked immunosorbent assay for the cytokines VEGF-A, tumor necrosis factor (TNF), interleukin 6 (IL-6), IL-8 (chemokine [CXCL]-8), IL-1β, IL-10, IL-12p70, IL-33, interferon (IFN)-γ, IFN-α, IFN-β, chemokine ligand (CCL)-3, IL-2, IL-5, IL-15, CXCL-10, CCL-2, IL-1Ra, CCL-5, IL-17, and CCL-11. Vitreous samples obtained at the time of macular hole surgery served as controls (n = 8). ResultsConcentrations of VEGF-A were significantly elevated in vitreous samples from individuals with exogenous endophthalmitis compared with macular hole (p < 0.001). VEGF-A was significantly upregulated in individuals with exogenous endophthalmitis after cataract surgery (p = 0.001), vitrectomy (p = 0.024), and intravitreal injection (p = 0.012). VEGF-A concentrations were similar in both culture-positive and culture-negative populations (p > 0.05). In a linear regression model, levels of VEGF-A correlated significantly with the chemokine CXCL-8 (p = 0.028). ConclusionsWe demonstrate that VEGF-A is potently upregulated in exogenous endophthalmitis. This observation provides a foundation for future studies of targeted VEGF-A blockade in the management of endophthalmitis.

VEGF-A Is Necessary and Sufficient for Retinal Neuroprotection in Models of Experimental Glaucoma

Vascular endothelial growth factor A (VEGF-A) is a validated therapeutic target in several angiogenic- and vascular permeability–related pathological conditions, including certain cancers and potentially blinding diseases, such as age-related macular degeneration and diabetic retinopathy. We and others have shown that VEGF-A also plays an important role in neuronal development and neuroprotection, including in the neural retina. Antagonism of VEGF-A function might therefore present a risk to neuronal survival as a significant adverse effect. Herein, we demonstrate that VEGF-A acts directly on retinal ganglion cells (RGCs) to promote survival. VEGF receptor-2 signaling via the phosphoinositide-3-kinase/Akt pathway was required for the survival response in isolated RGCs. These results were confirmed in animal models of staurosporine-induced RGC death and experimental hypertensive glaucoma. Importantly, we observed that VEGF-A blockade significantly exacerbated neuronal cell death in the hypertensive glaucoma model. Our findings highlight the need to better define the risks associated with use of VEGF-A antagonists in the ocular setting.

Bevacizumab potentiates chemotherapeutic effect on T-leukemia/lymphoma cells by direct action on tumor endothelial cells

Vascular endothelial growth factor-A, an angiogenesis stimulator expressed on both tumor endothelial and malignant T cells, is involved in tumor progression in T-leukemia/lymphoma. Here, we assessed the impact of therapeutic vascular endothelial growth factor-A blockade on tumor-endothelial cell interaction and on tumor progression. In a murine xenograft T-leukemia/lymphoma model, combined bevacizumab (monoclonal antibody against vascular endothelial growth factor-A) with doxorubicin, compared with doxorubicin alone, significantly delayed tumor growth and induced prevalence of tumor cell apoptosis over mitosis. More importantly, the combined treatment induced endothelial cell swelling, microvessel occlusions, and tumor necrosis. In vitro, co-culture of endothelial cells with T-leukemia/lymphoma cells showed that doxorubicin induced expression of intracellular cell adhesion molecule-1, provided endothelial and malignant T cells were in direct contact. This was abrogated by bevacizumab treatment with doxorubicin. Taken together, bevacizumab enhances the chemotherapeutic effect on T-leukemia/lymphoma cells. Directly targeting tumor endothelial cells might be a promising therapeutic strategy to counteract tumor progression in T-cell malignancies.

Effects of Bevacizumab on Autocrine VEGF Stimulation in Bladder Cancer Cell Lines

Introduction: A functional vascular endothelial growth factor A (VEGF-A) autocrine loop is crucial for bladder cancer cell survival. We reasoned that treatment with the anti-VEGF antibody bevacizumab may result either in cell growth prevention or in the cell adaptation to compensate VEGF deprivation. Methods: The cytotoxicity of different levels of bevacizumab and its effect on the gene expression was analyzed in human bladder cancer cell lines. Results: Inhibition of bladder cancer cell proliferation was observed at >2.5 mg/ml of bevacizumab. Non-muscle-invasive bladder cancer cells expressed high concentrations of VEGF-A, and were less susceptible to bevacizumab inhibition. At 0.5 mg/ml (FDA approved concentration) of bevacizumab, cells increase their expression of VEGF-A, VEGF-A receptors and related growth factors. Conclusions: Bevacizumab cytotoxicity is only observed at high concentration, and it is inversely correlated with the basal VEGF-A expression of the bladder cancer cells. This is the first report showing that, at clinical bevacizumab concentrations, cancer cells compensate the VEGF-A blockade, by improving the expression of VEGF-A and related genes, highlighting the need to follow the patient’s adaptation response to bevacizumab treatment.

The Absence of Pericytes Does Not Increase the Sensitivity of Tumor Vasculature to Vascular Endothelial Growth Factor-A Blockade

Recent progress with therapies targeting endothelial cells has drawn attention also to the pericytes as potential target cells for antiangiogenic therapy. Published data suggest that pericytes might confer resistance to vascular endothelial growth factor (VEGF) withdrawal in tumors. This hypothesis has been supported by experiments using tumors with reversible transgenic expression of VEGF-A as well as by individual pharmacologically targeting VEGF and platelet-derived growth factor receptor signaling in endothelial cells and pericytes using receptor tyrosine kinase (RTK) inhibitors with different specificities. However, the RTK inhibitors applied thus far are not entirely specific to the mentioned pathways, and therefore, the effects putatively attributed to pericyte targeting might reflect other antitumor effects. Here, we have reinvestigated the putative benefits of doubly targeting endothelial cells and pericytes in the treatment of experimental tumors. For this purpose, we used two highly specific tools, the pericyte-deficient pdgfb(ret/ret) mouse and the recently developed specific anti-VEGF-A antibody G6-31, which neutralizes both murine and human VEGF-A. We generated B16, Lewis lung carcinoma, and T241 subcutaneous tumors in both pdgfb(ret/ret) and control mice and treated these mice with G6-31. Our results fail to show any improved effect of VEGF inhibition, as measured by tumor growth or decrease in vascular density, in pericyte-deficient tumors compared with controls. Our observations suggest that additional targeting of pericytes does not increase the antitumor effect already generated by anti-VEGF drugs.

CCR3 is a target for age-related macular degeneration diagnosis and therapy

Age-related macular degeneration (AMD), a leading cause of blindness worldwide, is as prevalent as cancer in industrialized nations. Most blindness in AMD results from invasion of the retina by choroidal neovascularization (CNV). We report that the eosinophil/mast cell chemokine receptor CCR3 is specifically expressed in CNV endothelial cells in humans with AMD, and that, despite the expression of its ligands eotaxin-1, -2, and -3, neither eosinophils nor mast cells are present in human CNV. Genetic or pharmacological targeting of CCR3 or eotaxins inhibited injury-induced CNV in mice. CNV suppression by CCR3 blockade was due to direct inhibition of endothelial cell proliferation, and was uncoupled from inflammation as it occurred in mice lacking eosinophils or mast cells and was independent of macrophage and neutrophil recruitment. CCR3 blockade was more effective at reducing CNV than vascular endothelial growth factor-A (VEGF-A) neutralization, which is currently in clinical use, and, unlike VEGF-A blockade, not toxic to the mouse retina. In vivo imaging with CCR3-targeting quantum dots located spontaneous CNV invisible to standard fluorescein angiography in mice before retinal invasion. CCR3 targeting might reduce vision loss due to AMD through early detection and therapeutic angioinhibition.

VEGF-A Links Angiogenesis and Inflammation in Inflammatory Bowel Disease Pathogenesis

Vascular endothelial growth factor A (VEGF-A) mediates angiogenesis and might also have a role in inflammation and immunity. We examined whether VEGF-A signaling has a role in inflammatory bowel disease (IBD). Expression levels of VEGF-A, and its receptors VEGFR-1 and VEGFR-2, were examined in samples from patients with IBD and compared with those of controls. The capacity of VEGF-A to induce angiogenesis was tested in human intestinal microvascular endothelial cells using cell-migration and matrigel tubule-formation assays. Levels of vascular cellular adhesion molecule-1 and intercellular adhesion molecule were measured by flow cytometry to determine induction of inflammation; neutrophil adhesion was also assayed. Expression patterns were determined in tissues from mice with dextran sulfate sodium (DSS)-induced colitis; the effects of VEGF-A overexpression and blockade were assessed in these mice by adenoviral transfer of VEGF-A and soluble VEGFR-1. Intestinal angiogenesis was measured by quantitative CD31 staining and leukocyte adhesion in vivo by intravital microscopy. Levels of VEGF-A and VEGFR-2 increased in samples from patients with IBD and colitic mice. VEGF-A induced angiogenesis of human intestinal microvascular endothelial cells in vitro as well as an inflammatory phenotype and adherence of neutrophils to intestinal endothelium. Overexpression of VEGF-A in mice with DSS-induced colitis worsened their condition, whereas overexpression of soluble VEGFR-1 had the opposite effect. Furthermore, overexpression of VEGF-A increased mucosal angiogenesis and stimulated leukocyte adhesion in vivo. VEGF-A appears to be a novel mediator of IBD by promoting intestinal angiogenesis and inflammation. Agents that block VEGF-A signaling might reduce intestinal inflammation in patients with IBD.