Comparative evaluation of the antitumor activity of antiangiogenic proteins delivered by gene transfer

Functional screening of amplification outlier oncogenes in organoid models of early tumorigenesis

Somatic copy number gains are pervasive across cancer types, yet their roles in oncogenesis are insufficiently evaluated. This inadequacy is partly due to copy gains spanning large chromosomal regions, obscuring causal loci. Here, we employed organoid modeling to evaluate candidate oncogenic loci identified via integrative computational analysis of extreme copy gains overlapping with extreme expression dysregulation in The Cancer Genome Atlas. Subsets of "outlier" candidates were contextually screened as tissue-specific cDNA lentiviral libraries within cognate esophagus, oral cavity, colon, stomach, pancreas, and lung organoids bearing initial oncogenic mutations. Iterative analysis nominated the kinase DYRK2 at 12q15 as an amplified head and neck squamous carcinoma oncogene in p53-/- oral mucosal organoids. Similarly, FGF3, amplified at 11q13 in 41% of esophageal squamous carcinomas, promoted p53-/- esophageal organoid growth reversible by small molecule and soluble receptor antagonism of FGFRs. Our studies establish organoid-based contextual screening of candidate genomic drivers, enabling functional evaluation during early tumorigenesis.

Understanding the Neuroplastic Effects of Auricular Vagus Nerve Stimulation in Animal Models of Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

Transauricular vagus nerve stimulation (taVNS) is being studied as a feasible intervention for stroke, but the mechanisms by which this non-invasive technique acts in the cortex are still broadly unknown.

OBJECTIVES

This study aimed to systematically review the current pre-clinical evidence in the auricular vagus nerve stimulation (aVNS) neuroplastic effects in stroke.

METHODS

We searched, in December of 2022, in Medline, Cochrane, Embase, and Lilacs databases. The authors executed the extraction of the data on Excel. The risk of bias was evaluated by adapted Cochrane Collaboration's tool for animal studies (SYRCLES's RoB tool).

RESULTS

A total of 8 studies published between 2015 and 2022 were included in this review, including 391 animal models. In general, aVNS demonstrated a reduction in neurological deficits (SMD = -1.97, 95% CI -2.57 to -1.36, I2 = 44%), in time to perform the adhesive removal test (SMD = -2.26, 95% CI -4.45 to -0.08, I2 = 81%), and infarct size (SMD = -1.51, 95% CI -2.42 to -0.60, I2 = 58%). Regarding the neuroplasticity markers, aVNS showed to increase microcapillary density, CD31 proliferation, and BDNF protein levels and RNA expression.

CONCLUSIONS

The studies analyzed show a trend of results that demonstrate a significant effect of the auricular vagal nerve stimulation in stroke animal models. Although the aggregated results show high heterogeneity and high risk of bias. More studies are needed to create solid conclusions.

H3K27me3-modulated Hofbauer cell BMP2 signalling enhancement compensates for shallow trophoblast invasion in preeclampsia

BACKGROUND

Preeclampsia (PE) is a common hypertensive pregnancy disorder associated with shallow trophoblast invasion. Although bone morphogenetic protein 2 (BMP2) has been shown to promote trophoblast invasion in vitro, its cellular origin and molecular regulation in placenta, as well as its potential role in PE, has yet to be established. Additionally, whether BMP2 and/or its downstream molecules could serve as potential diagnostic or therapeutic targets for PE has not been explored.

METHODS

Placentas and sera from PE and healthy pregnant women were subjected to multi-omics analyses, immunoblots, qPCR, and ELISA assays. Immortalized trophoblast cells, primary cultures of human trophoblasts, and first-trimester villous explants were used for in vitro experiments. Adenovirus expressing sFlt-1 (Ad Flt1)-induced PE rat model was used for in vivo studies.

FINDINGS

We find globally decreased H3K27me3 modifications and increased BMP2 signalling in preeclamptic placentas, which is negatively correlated with clinical manifestations. BMP2 is derived from Hofbauer cells and epigenetically regulated by H3K27me3 modification. BMP2 promotes trophoblast invasion and vascular mimicry by upregulating BMP6 via BMPR1A-SMAD2/3-SMAD4 signalling. BMP2 supplementation alleviates high blood pressure and fetal growth restriction phenotypes in Ad Flt1-induced rat PE model.

INTERPRETATION

Our findings demonstrate that epigenetically regulated Hofbauer cell-derived BMP2 signalling enhancement in late gestation could serve as a compensatory response for shallow trophoblast invasion in PE, suggesting opportunities for diagnostic marker and therapeutic target applications in PE clinical management.

FUNDING

National Key Research and Development Program of China (2022YFC2702400), National Natural Science Foundation of China (82101784, 82171648, 31988101), and Natural Science Foundation of Shandong Province (ZR2020QH051, ZR2020MH039).

Design, synthesis and evaluation of anticancer activity of new pyrazoline derivatives by down-regulation of VEGF: Molecular docking and apoptosis inducing activity

Two series of pyrazoline compounds were designed and synthesized as antiproliferative agents by VEGFR pathway inhibition. All synthesized compounds were screened by the National Cancer Institute (NCI), Bethesda, USA for anticancer activity against 60 human cancer cell lines. Compound 3f exhibited the highest anticancer activity on the ovarian cell line (OVCAR-4) with IC₅₀ = 0.29 μM and on the breast cell line (MDA-MB-468) with IC₅₀ = 0.35 μM. It also exhibited the highest selectivity index (SI = 74). Compound 3f caused cell cycle arrest in OVCAR-4 cell line at the S phase which consequently inhibited cell proliferation and induced apoptosis. Moreover, 3f showed potent down-regulation of VEGF and p-VEGFR-2. Docking studies showed that compound 3f interacts in a similar pattern to axitinib on the VEGFR-2 receptor. The same compound was also able to fit into the gorge of STAT3 binding site, the transcription factor for VEGF, which explains the VEGF down-regulation.

Beyond cancer cells: Targeting the tumor microenvironment with gene therapy and armed oncolytic virus

Cancer gene therapies are usually designed either to express wild-type copies of tumor suppressor genes or to exploit tumor-associated phenotypic changes to endow selective cytotoxicity. However, these approaches become less relevant to cancers that contain many independent mutations, and the situation is made more complex by our increased understanding of clonal evolution of tumors, meaning that different metastases and even regions of the same tumor mass have distinct mutational and phenotypic profiles. In contrast, the relatively genetically stable tumor microenvironment (TME) therefore provides an appealing therapeutic target, particularly since it plays an essential role in promoting cancer growth, immune tolerance, and acquired resistance to many therapies. Recently, a variety of different TME-targeted gene therapy and armed oncolytic strategies have been explored, with particular success observed in strategies targeting the cancer stroma, reducing tumor vasculature, and repolarizing the immunosuppressive microenvironment. Herein, we review the progress of these TME-targeting approaches and try to highlight those showing the greatest promise.

Targeting Neuropilin-1 with Nanobodies Reduces Colorectal Carcinoma Development

Simple Summary

Neuropilin-1 is a co-receptor for semaphorins and vascular endothelial growth factor family members. Neuropilin-1 can be expressed on tumor cells, tumor-infiltrating myeloid and lymphoid cells and has been linked to a tumor-promoting environment. We investigated nanobodies (Nbs) targeting neuropilin-1 for their potential to hamper colorectal carcinoma development in mice. Our data suggest that targeting neuropilin-1 in cancer using neuropilin-1 blocking Nbs delays tumor growth and extends the survival through a shift in the anti-tumor macrophage/pro-tumor macrophage ratio and activation of colorectal cancer-specific CD8⁺ T cells. These findings provide a rationale for the further development of Nbs targeting human neuropilin-1 and bringing them from the bench to the bedside.

Abstract

Neuropilin-1 (NRP-1) is a co-receptor for semaphorins and vascular endothelial growth factor (VEGF) family members that can be expressed on cancer cells and tumor-infiltrating myeloid, endothelial and lymphoid cells. It has been linked to a tumor-promoting environment upon interaction with semaphorin 3A (Sema3A). Nanobodies (Nbs) targeting NRP-1 were generated for their potential to hamper the NRP-1/Sema3A interaction and their impact on colorectal carcinoma (CRC) development was evaluated in vivo through the generation of anti-NRP-1-producing CRC cells. We observed that tumor growth was significantly delayed and survival prolonged when the anti-NRP-1 Nbs were produced in vivo. We further analyzed the tumor microenvironment and observed that the pro-inflammatory MHC-II^high/trophic MHC-II^low macrophage ratio was increased in tumors that produce anti-NRP-1 Nbs. This finding was corroborated by an increase in the expression of genes associated with MHC-II^high macrophages and a decrease in the expression of MHC-II^low macrophage-associated genes in the macrophage pool sorted from anti-NRP-1 Nb-producing tumors. Moreover, we observed a significantly higher percentage of tumor-associated antigen-specific CD8⁺ T cells in tumors producing anti-NRP-1 Nbs. These data demonstrate that an intratumoral expression of NRP-1/Sema3A blocking biologicals increases anti-tumor immunity.

Inhibition of VEGF (Vascular Endothelial Growth Factor)-A or its Receptor Activity Suppresses Experimental Aneurysm Progression in the Aortic Elastase Infusion Model

OBJECTIVE

We examined the pathogenic significance of VEGF (vascular endothelial growth factor)-A in experimental abdominal aortic aneurysms (AAAs) and the translational value of pharmacological VEGF-A or its receptor inhibition in aneurysm suppression. Approaches and Results: AAAs were created in male C57BL/6J mice via intra-aortic elastase infusion. Soluble VEGFR (VEGF receptor)-2 extracellular ligand-binding domain (delivered in Ad [adenovirus]-VEGFR-2), anti-VEGF-A mAb (monoclonal antibody), and sunitinib were used to sequester VEGF-A, neutralize VEGF-A, and inhibit receptor tyrosine kinase activity, respectively. Influences on AAAs were assessed using ultrasonography and histopathology. In vitro transwell migration and quantitative reverse transcription polymerase chain reaction assays were used to assess myeloid cell chemotaxis and mRNA expression, respectively. Abundant VEGF-A mRNA and VEGF-A-positive cells were present in aneurysmal aortae. Sequestration of VEGF-A by Ad-VEGFR-2 prevented AAA formation, with attenuation of medial elastolysis and smooth muscle depletion, mural angiogenesis and monocyte/macrophage infiltration. Treatment with anti-VEGF-A mAb prevented AAA formation without affecting further progression of established AAAs. Sunitinib therapy substantially mitigated both AAA formation and further progression of established AAAs, attenuated aneurysmal aortic MMP2 (matrix metalloproteinase) and MMP9 protein expression, inhibited inflammatory monocyte and neutrophil chemotaxis to VEGF-A, and reduced MMP2, MMP9, and VEGF-A mRNA expression in macrophages and smooth muscle cells in vitro. Additionally, sunitinib treatment reduced circulating monocytes in aneurysmal mice.

CONCLUSIONS

VEGF-A and its receptors contribute to experimental AAA formation by suppressing mural angiogenesis, MMP and VEGF-A production, myeloid cell chemotaxis, and circulating monocytes. Pharmacological inhibition of receptor tyrosine kinases by sunitinib or related compounds may provide novel opportunities for clinical aneurysm suppression.

A RECK-WNT7 Receptor-Ligand Interaction Enables Isoform-Specific Regulation of Wnt Bioavailability

WNT7A and WNT7B control CNS angiogenesis and blood-brain barrier formation by activating endothelial Wnt/β-catenin signaling. The GPI-anchored protein RECK and adhesion G protein-coupled receptor GPR124 critically regulate WNT7-specific signaling in concert with FZD and LRP co-receptors. Here, we demonstrate that primarily the GPR124 ectodomain, but not its transmembrane and intracellular domains, mediates RECK/WNT7-induced canonical Wnt signaling. Moreover, RECK is the predominant binding partner of GPR124 in rat brain blood vessels in situ. WNT7A and WNT7B, but not WNT3A, directly bind to purified recombinant soluble RECK, full-length cell surface RECK, and the GPR124:RECK complex. Chemical cross-linking indicates that RECK and WNT7A associate with 1:1 stoichiometry, which stabilizes short-lived, active, monomeric, hydrophobic WNT7A. In contrast, free WNT7A rapidly converts into inactive, hydrophilic aggregates. Overall, RECK is a selective WNT7 receptor that mediates GPR124/FZD/LRP-dependent canonical Wnt/β-catenin signaling by stabilizing active cell surface WNT7, suggesting isoform-specific regulation of Wnt bioavailability.

Preparation of endostatin-loaded chitosan nanoparticles and evaluation of the antitumor effect of such nanoparticles on the Lewis lung cancer model

The purpose of this study was to prepare ES-loaded chitosan nanoparticles (ES-NPs) and evaluate the antitumor effect of these particles on the Lewis lung cancer model. ES-NPs were prepared by a simple ionic cross-linking method. The characterization of the ES-NPs, including size distribution, zeta potential, loading efficiency and encapsulation efficiency (EE), was performed. An in vitro release test was also used to determine the release behavior of the ES-NPs. Cell viability and cell migration were assayed to detect the in vitro antiangiogenic effect of ES-NPs. In order to clarify the antitumor effect of ES-NPs in vivo, the Lewis lung cancer model was used. ES-NPs were successfully synthesized and shown to have a suitable size distribution and high EE. The nanoparticles were spherical and homogeneous in shape and exhibited an ideal releasing profile in vitro. Moreover, ES-NPs significantly inhibited the proliferation and migration of human umbilical vascular endothelial cells (HUVECs). The in vivo antiangiogenic activity was evaluated by ELISA and immunohistochemistry analyses, which revealed that ES-NPs had a stronger antiangiogenic effect for reinforced anticancer activity. Indeed, even the treatment cycle in which ES-NPs were injected every seven days, showed stronger antitumor effect than the free ES injected for 14 consecutive days. Our study confirmed that the CS nanoparticle is a feasible carrier for endostatin to be used in the treatment of lung cancer.

Gene Therapy for Pancreatic Cancer: Specificity, Issues and Hopes

A recent death projection has placed pancreatic ductal adenocarcinoma as the second cause of death by cancer in 2030. The prognosis for pancreatic cancer is very poor and there is a great need for new treatments that can change this poor outcome. Developments of therapeutic innovations in combination with conventional chemotherapy are needed urgently. Among innovative treatments the gene therapy offers a promising avenue. The present review gives an overview of the general strategy of gene therapy as well as the limitations and stakes of the different experimental in vivo models, expression vectors (synthetic and viral), molecular tools (interference RNA, genome editing) and therapeutic genes (tumor suppressor genes, antiangiogenic and pro-apoptotic genes, suicide genes). The latest developments in pancreatic carcinoma gene therapy are described including gene-based tumor cell sensitization to chemotherapy, vaccination and adoptive immunotherapy (chimeric antigen receptor T-cells strategy). Nowadays, there is a specific development of oncolytic virus therapies including oncolytic adenoviruses, herpes virus, parvovirus or reovirus. A summary of all published and on-going phase-1 trials is given. Most of them associate gene therapy and chemotherapy or radiochemotherapy. The first results are encouraging for most of the trials but remain to be confirmed in phase 2 trials.

Gpr124 is essential for blood-brain barrier integrity in central nervous system disease

Although blood-brain barrier (BBB) compromise is central to the etiology of diverse central nervous system (CNS) disorders, endothelial receptor proteins that control BBB function are poorly defined. The endothelial G-protein-coupled receptor (GPCR) Gpr124 has been reported to be required for normal forebrain angiogenesis and BBB function in mouse embryos, but the role of this receptor in adult animals is unknown. Here Gpr124 conditional knockout (CKO) in the endothelia of adult mice did not affect homeostatic BBB integrity, but resulted in BBB disruption and microvascular hemorrhage in mouse models of both ischemic stroke and glioblastoma, accompanied by reduced cerebrovascular canonical Wnt-β-catenin signaling. Constitutive activation of Wnt-β-catenin signaling fully corrected the BBB disruption and hemorrhage defects of Gpr124-CKO mice, with rescue of the endothelial gene tight junction, pericyte coverage and extracellular-matrix deficits. We thus identify Gpr124 as an endothelial GPCR specifically required for endothelial Wnt signaling and BBB integrity under pathological conditions in adult mice. This finding implicates Gpr124 as a potential therapeutic target for human CNS disorders characterized by BBB disruption.

Nicotinamide benefits both mothers and pups in two contrasting mouse models of preeclampsia

Preeclampsia (PE) complicates ∼5% of human pregnancies and is one of the leading causes of pregnancy-related maternal deaths. The only definitive treatment, induced delivery, invariably results in prematurity, and in severe early-onset cases may lead to fetal death. Many currently available antihypertensive drugs are teratogenic and therefore precluded from use. Nonteratogenic antihypertensives help control maternal blood pressure in PE, but results in preventing preterm delivery and correcting fetal growth restriction (FGR) that also occurs in PE have been disappointing. Here we show that dietary nicotinamide, a nonteratogenic amide of vitamin B₃, improves the maternal condition, prolongs pregnancies, and prevents FGR in two contrasting mouse models of PE. The first is caused by endotheliosis due to excess levels in the mothers of a soluble form of the receptor for vascular endothelial growth factor (VEGF), which binds to and inactivates VEGF. The second is caused by genetic absence of Ankiryn-repeat-and-SOCS-box-containing-protein 4, a factor that contributes to the differentiation of trophoblast stem cells into the giant trophoblast cells necessary for embryo implantation in mice; its absence leads to impaired placental development. In both models, fetal production of ATP is impaired and FGR is observed. We show here that nicotinamide decreases blood pressure and endotheliosis in the mothers, probably by inhibiting ADP ribosyl cyclase (ADPRC), and prevents FGR, probably by normalizing fetal ATP synthesis via the nucleotide salvage pathway. Because nicotinamide benefits both dams and pups, it merits evaluation for preventing or treating PE in humans.

Endostatin and endorepellin: A common route of action for similar angiostatic cancer avengers

Traditional cancer therapy typically targets the tumor proper. However, newly-formed vasculature exerts a major role in cancer development and progression. Autophagy, as a biological mechanism for clearing damaged proteins and oxidative stress products released in the tumor milieu, could help in tumor resolution by rescuing cells undergoing modifications or inducing autophagic-cell death of tumor blood vessels. Cleaved fragments of extracellular matrix proteoglycans are emerging as key players in the modulation of angiogenesis and endothelial cell autophagy. An essential characteristic of cancer progression is the remodeling of the basement membrane and the release of processed forms of its constituents. Endostatin, generated from collagen XVIII, and endorepellin, the C-terminal segment of the large proteoglycan perlecan, possess a dual activity as modifiers of both angiogenesis and endothelial cell autophagy. Manipulation of these endogenously-processed forms, located in the basement membrane within tumors, could represent new therapeutic approaches for cancer eradication.

Antiangiogenic therapies for glioblastoma

Glioblastoma is the most prevalent malignant primary brain tumor in adults and to date effective durable treatments are lacking. Preclinical studies underscore the importance of neovascularization for tumor survival, making angiogenesis an important treatment target. Early clinical experience in recurrent glioblastoma suggested that antiangiogenic agents may provide clinical benefit by prolonging progression-free survival, improving quality of life and decreasing peritumoral edema. Two recent Phase III randomized trials of antiangiogenic therapy at initial diagnosis suggested improvement in progression-free survival, but failed to show an overall survival benefit. Ongoing preclinical research focuses on mechanisms of resistance and potential predictive biomarkers. Identification of targets to resistance pathways and of predictive biomarkers will hopefully improve efficacy of antiangiogenic therapies.

Novel therapeutic strategies in human malignancy: combining immunotherapy and oncolytic virotherapy

Results from randomized clinical trials over the last several years have finally begun to demonstrate the potential of oncolytic viral therapies to treat a variety of cancers. One reason for these successes has been the realization that this platform is most effective when considered primarily as an immunotherapy. Cancer immunotherapy has also made dramatic strides recently with antibodies capable of blocking immune checkpoint inhibitors and adoptive T-cell therapies, notably CAR T-cells, leading a panel of novel and highly clinically effective therapies. It is clear therefore that an understanding of how and when these complementary approaches can most effectively be combined offers the real hope of moving beyond simply treating the disease and toward starting to talk about curative therapies. In this review we discuss approaches to combining these therapeutic platforms, both through engineering the viral vectors to more beneficially interact with the host immune response during therapy, as well as through the direct combinations of different therapeutics. This primarily, but not exclusively focuses on strains of oncolytic vaccinia virus. Some of the results reported to date, primarily in pre-clinical models but also in early clinical trials, are dramatic and hold great promise for the future development of similar therapies and their translation into cancer therapies.

Combinatorial anti-angiogenic gene therapy in a human malignant mesothelioma model

Anti-angiogenic gene therapy represents a promising strategy for cancer; however, it has rarely been tested in malignant mesothelioma, a highly aggressive tumor associated with asbestos with poor prognosis. In the present study, we investigated whether anti-angiogenic factors such as angiostatin, endostatin and the soluble form of vascular endothelial growth factor receptor 2 (sFlk1) were able to inhibit endothelial cell proliferation via lentivirus-mediated gene transfer into malignant mesothelioma cells in culture. We also assessed whether a dual-agent strategy had greater therapeutic benefit. Human malignant pleural mesothelioma MSTO-211H cells were transduced using lentiviral vectors that individually expressed angiostatin, endostatin and sFlk1 and linked to enhanced green fluorescent protein (EGFP) marker gene expression via an internal ribosome entry site. The lentivirus expressing EGFP alone was used as a control. The resultant cells designated as MSTO-A, MSTO-E, MSTO-F and MSTO-C were confirmed by western blot analysis and fluorescence microscopy to stably express the corresponding proteins. No differences were observed in the in vitro growth rates between any of these cells. However, co-culture of MSTO-A, MSTO-E and MSTO-F showed significant suppression of human umbilical endothelial cell growth in vitro compared with that of MSTO-C. Furthermore, a combination of any two among MSTO-A, MSTO-E and MSTO-F significantly enhanced efficacy. These results suggest that combinatorial anti-angiogenic gene therapy targeting different pathways of endothelial growth factor signaling has the potential for greater therapeutic efficacy than that of a single-agent regimen.

ADAMTS13 Endopeptidase Protects against Vascular Endothelial Growth Factor Inhibitor-Induced Thrombotic Microangiopathy

Thrombotic microangiopathy (TMA) is a life-threatening condition that affects some, but not all, recipients of vascular endothelial growth factor (VEGF) inhibitors given as part of chemotherapy. TMA is also a complication of preeclampsia, a disease characterized by excess production of the VEGF-scavenging soluble VEGF receptor 1 (soluble fms-like tyrosine kinase 1; sFlt-1). Risk factors for VEGF inhibitor-related TMA remain unknown. We hypothesized that deficiency of the VWF-cleaving ADAMTS13 endopeptidase contributes to the development of VEGF inhibitor-related TMA. ADAMTS13(-/-) mice overexpressing sFlt-1 presented all hallmarks of TMA, including thrombocytopenia, schistocytosis, anemia, and VWF-positive microthrombi in multiple organs. Similar to VEGF inhibitor-related TMA in humans, these mice exhibited severely impaired kidney function and hypertension. In contrast, wild-type mice overexpressing sFlt-1 developed modest hypertension but no other features of TMA. Recombinant ADAMTS13 therapy ameliorated all symptoms of TMA in ADAMTS13(-/-) mice overexpressing sFlt-1 and normalized BP in wild-type mice. ADAMTS13 activity may thus be a critical determinant for the development of TMA secondary to VEGF inhibition. Administration of recombinant ADAMTS13 may serve as a therapeutic approach to treat or prevent thrombotic complications of VEGF inhibition.

Potent and long-term antiangiogenic efficacy mediated by FP3-expressing oncolytic adenovirus

Various ways to inhibit vascular endothelial growth factor (VEGF), a key facilitator in tumor angiogenesis, are being developed to treat cancer. The soluble VEGF decoy receptor (FP3), due to its high affinity to VEGF, is a highly effective and promising strategy to disrupt VEGF signaling pathway. Despite potential advantage and potent therapeutic efficacy, its employment has been limited by very poor in vivo pharmacokinetic properties. To address this challenge, we designed a novel oncolytic adenovirus (Ad) expressing FP3 (RdB/FP3). To demonstrate the VEGF-specific nature of RdB/FP3, replication-incompetent Ad expressing FP3 (dE1/FP3) was also generated. dE1/FP3 was highly effective in reducing VEGF expression and functionally elicited an antiangiogeneic effect. Furthermore, RdB/FP3 exhibited a potent antitumor effect compared with RdB or recombinant FP3. Consistent with these data, RdB/FP3 was shown to greatly decrease VEGF expression level and vessel density and increase apoptosis in both tumor endothelial and tumor cells, verifying potent suppressive effects of RdB/FP3 on VEGF-mediated tumor angiogenesis in vivo. Importantly, the therapeutic mechanism of antitumor effect mediated by RdB/FP3 is associated with prolonged VEGF silencing efficacy and enhanced oncolysis via cancer cell-specific replication of oncolytic Ad. Taken together, RdB/FP3 provides a new promising therapeutic approach in the treatment of cancer and angiogenesis-related diseases.

Levels of bone marrow microvessel density are crucial for evaluating the status of acute myeloid leukemia

The aim of the present study was to determine the efficacy of bone marrow microvessel density (BM-MVD) in the evaluation of the status of acute myeloid leukemia (AML). The levels of serum and bone marrow vascular endothelial growth factor (VEGF), and BM-MVD in 28 patients with AML, 10 patients with non-Hodgkin's lymphoma, 10 patients with anemia and 14 patients with AML that achieved complete remission for six months (AML-DFS) subsequent to chemotherapy were determined by ELISA and immunohistochemistry. The levels of serum VEGF in patients with hematological disorders were significantly increased compared with the levels in the healthy controls. The levels of BM VEGF and BM-MVD in AML patients were significantly higher compared with the levels in the patients with non-Hodgkin's lymphoma or anemia. Following chemotherapy, the levels of serum VEGF significantly increased and the levels of BM VEGF decreased in the AML patients, regardless of their therapeutic responses, compared with the levels prior to treatment. By contrast, the levels of BM-MVD in the AML patients were significantly reduced in the patients that completely recovered from AML (AML-DFS group), compared with those in other groups. The present data indicate that the levels of BM-MVD are valuable for evaluating the status of AML.

TTAC-0001, a human monoclonal antibody targeting VEGFR-2/KDR, blocks tumor angiogenesis

Angiogenesis is one of the most important processes for cancer cell survival, tumor growth and metastasis. Vascular endothelial growth factor (VEGF) and its receptor, particularly VEGF receptor-2 (VEGFR-2, or kinase insert domain-containing receptor, KDR), play critical roles in tumor-associated angiogenesis. We developed TTAC-0001, a human monoclonal antibody against VEGFR-2/KDR from a fully human naïve single-chain variable fragment phage library. TTAC-0001 was selected as a lead candidate based on its affinity, ligand binding inhibition and inhibition of VEGFR-2 signal in human umbilical vein endothelial cells (HUVEC). TTAC-0001 inhibited binding of VEGF-C and VEGF-D to VEGFR-2 in addition to VEGF-A. It binds on the N-terminal regions of domain 2 and domain 3 of VEGFR-2. It could inhibit the phosphorylation of VEGFR-2/KDR and ERK induced by VEGF in HUVEC. TTAC-0001 also inhibited VEGF-mediated endothelial cell proliferation, migration and tube formation in vitro, as well as ex vivo vessel sprouting from rat aortic rings and neovascularization in mouse matrigel model in vivo. Our data indicates that TTAC-0001 blocks the binding of VEGFs to VEGFR-2/KDR and inhibits VEGFR-induced signaling pathways and angiogenesis. Therefore, these data strongly support the further development of TTAC-0001 as an anti-cancer agent in the clinic.

Novel glycosylated VEGF decoy receptor fusion protein, VEGF-Grab, efficiently suppresses tumor angiogenesis and progression

Antiangiogenic therapies targeting VEGFA have been commonly used in clinics to treat cancers over the past decade. However, their clinical efficacy has been limited, with drawbacks including acquisition of resistance and activation of compensatory pathways resulting from elevated circulating VEGFB and placental growth factor (PlGF). To bypass these disadvantages, we developed a novel glycosylated soluble decoy receptor fusion protein, VEGF-Grab, that can neutralize VEGFA, VEGFB, and PlGF. VEGF-Grab has the second and third immunoglobulin (Ig)-like domains of VEGF receptor 1 (VEGFR1) fused to IgG1 Fc, with three potential glycosylation sites introduced into the third Ig-like domain of VEGF-Grab by mutagenesis. Compared with VEGF-Trap, VEGF-Grab showed more potent decoy activity against VEGF and PlGF, mainly attributed to the VEGFR1 backbone. Most importantly, the negatively charged O-glycans attached to the third Ig-like domain of VEGFR1 counterbalanced the originally positively charged VEGFR1 backbone, minimizing nonspecific binding of VEGF-Grab to the extracellular matrix, and resulting in greatly improved pharmacokinetic profile. These advancements led to stronger and more durable antiangiogenic, antitumor, and antimetastatic efficacy in both implanted and spontaneous tumor models as compared with VEGF-Trap, while toxicity profiles were comparable with VEGF-Trap. Collectively, our results highlight VEGF-Grab as a promising therapeutic candidate for further clinical drug development.

Gene therapy in pancreatic cancer

Pancreatic cancer (PC) is a highly lethal disease and notoriously difficult to treat. Only a small proportion of PC patients are eligible for surgical resection, whilst conventional chemoradiotherapy only has a modest effect with substantial toxicity. Gene therapy has become a new widely investigated therapeutic approach for PC. This article reviews the basic rationale, gene delivery methods, therapeutic targets and developments of laboratory research and clinical trials in gene therapy of PC by searching the literature published in English using the PubMed database and analyzing clinical trials registered on the Gene Therapy Clinical Trials Worldwide website (http://www. wiley.co.uk/genmed/ clinical). Viral vectors are main gene delivery tools in gene therapy of cancer, and especially, oncolytic virus shows brighter prospect due to its tumor-targeting property. Efficient therapeutic targets for gene therapy include tumor suppressor gene p53, mutant oncogene K-ras, anti-angiogenesis gene VEGFR, suicide gene HSK-TK, cytosine deaminase and cytochrome p450, multiple cytokine genes and so on. Combining different targets or combination strategies with traditional chemoradiotherapy may be a more effective approach to improve the efficacy of cancer gene therapy. Cancer gene therapy is not yet applied in clinical practice, but basic and clinical studies have demonstrated its safety and clinical benefits. Gene therapy will be a new and promising field for the treatment of PC.

Optical coherence tomographic and visual results at six months after transitioning to aflibercept for patients on prior ranibizumab or bevacizumab treatment for exudative age-related macular degeneration (an American Ophthalmological Society thesis)

PURPOSE

To study optical coherence tomographic (OCT) results and vision at 6 months after transition (post-Tx) from intravitreal bevacizumab and/or ranibizumab to aflibercept for treatment of neovascular age-related macular degeneration (nAMD). The null hypothesis was the lack of improvements in OCT metrics and vision outcome in study eyes at 6 months after transitioning from bevacizumab or ranibizumab to aflibercept.

METHODS

This retrospective study assessed 6 monthly OCT (Cirrus) data after transitioning to aflibercept for eyes on prior Legacy-ranibizumab, Legacy-bevacizumab, or mixed treatment for nAMD. Outcome measures were subretinal fluid (SRF), cystoid macular edema (CME), pigment epithelial detachment (PED) heights and volumes, central 1- and 3-mm subfield, Macular Volume, and best spectacle and pinhole visual acuity (VA). A single masked investigator performed all OCT measurements.

RESULTS

One hundred eighty-nine eyes in 172 patients in Legacy-bevacizumab (95 eyes), Legacy-ranibizumab (84 eyes), or Mixed Group(10 eyes) were switched to aflibercept and followed for 6 months. Significant post-Tx reductions were noted in SRF/CME heights and volumes (all P<.001). Similar findings were noted for PED heights (122.8 μm vs 79.4 μm) and PED volumes (all P<.001). Post-Tx VA was better (20/43 vs 20/51, P<.001). There were no differences between Legacy-bevacizumab and Legacy-ranibizumab groups in OCT and VA changes. Post-Tx VA, SRF/CME, and PED heights and volumes were improved for Nonresponders (suboptimal response to bevacizumab/ranibizumab) (P=.001 to <.001), but not Responders (good responses to same). The only adverse event was a retinal pigment epithelial tear in one eye.

CONCLUSIONS

Significant improvements in vision and OCT metrics developed in Nonresponders but not in Responders. Post-Tx VA and OCT measures were similar for eyes on prior bevacizumab or ranibizumab. Post-Tx adverse events were uncommon.

Oncolytic vaccinia virus demonstrates antiangiogenic effects mediated by targeting of VEGF

Oncolytic vaccinia virus has been shown to induce a profound, rapid and tumor-specific vascular collapse in both preclinical models and clinical studies; however, a complete examination of the kinetics and levels of collapse and revascularization has not been described previously. Contrast-enhanced ultrasound was used to follow tumor perfusion levels in mouse tumor models at times after vaccinia therapy. It was observed that revascularization after viral therapy was dramatically delayed and did not occur until after viral clearance. This indicated that oncolytic vaccinia may possess a previously undescribed antiangiogenic potential that might synergize with the reported anti-vascular effects. Despite a rapid loss of perfusion and widespread hypoxia within the tumor, it was observed that VEGF levels in the tumor were suppressed throughout the period of active viral infection. Although tumor vasculature could eventually reform after the viral therapy was cleared in mouse models, anti-tumor effects could be significantly enhanced through additional combination with anti-VEGF therapies. This was initially examined using a gene therapy approach (Ad-Flk1-Fc) to target VEGF directly, demonstrating that the timing of application of the antiangiogenic therapy was critical. However, it is also known that oncolytic vaccinia sensitizes tumors to tyrosine kinase inhibitors (TKI) in the clinic through an unknown mechanism. It is possible this phenomenon may be mediated through the antiangiogenic effects of the TKIs. This was modeled in mouse tumors using sunitinib in combination with oncolytic vaccinia. It was observed that prevention of angiogenesis mediated by oncolytic vaccinia can be utilized to enhance the TKI therapy.

Preliminary safety evaluation of a taurocholate-conjugated low-molecular-weight heparin derivative (LHT7): a potent angiogenesis inhibitor

In our previous studies, taurocholic acid (TA)-conjugated low-molecular-weight heparin derivative (LHT7) has been proven to be a potent anti-angiogenic agent by demonstrated successful blockage capability of vascular endothelial growth factors (VEGF). Preliminary safety evaluations were conducted based on its mechanism of action and chemical behavior. For this purpose, acute toxicity study, and hematological and serological evaluations were carried out. Additionally, in order to evaluate mechanism-related side effects, both blood pressure and the occurrence of proteinuria were measured using a treatment regime of multiple high doses of LHT7 in a biodistribution study. LD50 values for LHT7 in female and male mice were 56.9 and 64.7 mg kg(-1) doses, respectively. There were no vital fluctuations in the serological and hematological parameters, except for the elevated levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) at 100 and 200 mg kg(-1) doses of LHT7, representing vital changes in the liver function. Moreover, the results of mechanism-related studies showed that blood pressure at 50 mg kg(-1) did not change but showed elevated levels of protein in urine. In the biodistribution study, a slight accumulation of LHT7 in the kidney and the liver were observed at the 50 mg kg(-1) repeated dose owing to the presence of bile acid. No fatal damage was observed in this study; most observations were related to the chemical composition or the mechanism of action of the material.

Hydrogen sulfide attenuates sFlt1-induced hypertension and renal damage by upregulating vascular endothelial growth factor

Soluble fms-like tyrosine kinase 1 (sFlt1), a circulating antiangiogenic protein, is elevated in kidney diseases and contributes to the development of preeclampsia. Hydrogen sulfide is a vasorelaxant and proangiogenic gas with therapeutic potential in several diseases. Therefore, we evaluated the potential therapeutic effect and mechanisms of action of hydrogen sulfide in an animal model of sFlt1-induced hypertension, proteinuria, and glomerular endotheliosis created by adenovirus-mediated overexpression of sFlt1 in Sprague-Dawley rats. We injected sFlt1-overexpressing animals intraperitoneally with the hydrogen sulfide-donor sodium hydrosulfide (NaHS) (50 µmol/kg, twice daily) or vehicle (n=7 per group). Treatment with NaHS for 8 days significantly reduced sFlt1-induced hypertension, proteinuria, and glomerular endotheliosis. Measurement of plasma protein concentrations with ELISA revealed a reduction of free plasma sFlt1 and an increase of free plasma vascular endothelial growth factor (VEGF) after treatment with NaHS. Renal VEGF-A mRNA expression increased significantly with NaHS treatment. In vitro, NaHS was proangiogenic in an endothelial tube assay and attenuated the antiangiogenic effects of sFlt1. Stimulation of podocytes with NaHS resulted in both short-term VEGF release (120 minutes) and upregulation of VEGF-A mRNA levels (24 hours). Furthermore, pretreatment of mesenteric vessels with a VEGF receptor 2-neutralizing antibody significantly attenuated NaHS-induced vasodilation. These results suggest that hydrogen sulfide ameliorates sFlt1-induced hypertension, proteinuria, and glomerular endotheliosis in rats by increasing VEGF expression. Further studies are warranted to evaluate the role of hydrogen sulfide as a novel therapeutic agent for vascular disorders such as preeclampsia.

A liver Hif-2α-Irs2 pathway sensitizes hepatic insulin signaling and is modulated by Vegf inhibition

Insulin initiates diverse hepatic metabolic responses, including gluconeogenic suppression and induction of glycogen synthesis and lipogenesis. The liver possesses a rich sinusoidal capillary network with a higher degree of hypoxia and lower gluconeogenesis in the perivenous zone as compared to the rest of the organ. Here, we show that diverse vascular endothelial growth factor (VEGF) inhibitors improved glucose tolerance in nondiabetic C57BL/6 and diabetic db/db mice, potentiating hepatic insulin signaling with lower gluconeogenic gene expression, higher glycogen storage and suppressed hepatic glucose production. VEGF inhibition induced hepatic hypoxia through sinusoidal vascular regression and sensitized liver insulin signaling through hypoxia-inducible factor-2α (Hif-2α, encoded by Epas1) stabilization. Notably, liver-specific constitutive activation of HIF-2α, but not HIF-1α, was sufficient to augment hepatic insulin signaling through direct and indirect induction of insulin receptor substrate-2 (Irs2), an essential insulin receptor adaptor protein. Further, liver Irs2 was both necessary and sufficient to mediate Hif-2α and Vegf inhibition effects on glucose tolerance and hepatic insulin signaling. These results demonstrate an unsuspected intersection between Hif-2α-mediated hypoxic signaling and hepatic insulin action through Irs2 induction, which can be co-opted by Vegf inhibitors to modulate glucose metabolism. These studies also indicate distinct roles in hepatic metabolism for Hif-1α, which promotes glycolysis, and Hif-2α, which suppresses gluconeogenesis, and suggest new treatment approaches for type 2 diabetes mellitus.

Cloning and expression of soluble vascular endothelial growth factors receptor-1 (sFlt-1) fragments in CHO-K1

Soluble form of vascular endothelial growth factor (VEGF) receptor (sFlt-1) has been considered a key target in anti angiogenesis strategies. In this study, sFlt-1 was amplified and cloned. For recombinant production of sFlt-1 protein, Chinese hamster ovary cell line (CHO) was used. The liposome-mediated transfection with sFlt-1 gene, were detected in sFlt-1 positive cells as early as 24 hours post-transfection. The production of sFlt-1 protein was confirmed using SDS-PAGE and immune blotting results. In present investigation, the recombinant protein of sFlt-1 had expressed with correct folding. The system is economically applicable for large production of sFlt protein and can be used as further therapeutic approaches in targeting the growth of solid tumor tissue.

Antiangiogenic agents in advanced, persistent or recurrent endometrial cancer: a novel treatment option

The limited efficacy of endocrine therapy and chemotherapy has stimulated several researches aimed to detect novel molecularly target therapies for advanced, persistent or recurrent endometrial cancer. Prior attempts to block vascular endothelial growth factor (VEGF) with sunitinib, sorafenib and thalidomide have obtained disappointing results. Bevacizumab has shown a promising activity in a phase II study. The percentages of patients with progression-free survival ≥6 months were similar for endometrioid (35%) and serous carcinoma (36%), but the number of cases was too small to assess the relevance of histological type for response to bevacizumab. In a phase II study, aflibercept was administered every 2 weeks to women with recurrent or persistent disease after chemotherapy. Forty-one percent of the patients were progression-free at 6 months, but 32% of the women had been removed from study because of toxicity. The detection of activating mutations of Fibroblast Growth Factor Receptor (FGFR)-2 in primary endometrial carcinoma has generated a new avenue for the development of molecularly target agents. Dovitinib, a tyrosine kinase inhibitor targeting both VEGF receptor (VEGFR) and FGFRs, is under clinical investigation in different malignancies including endometrial cancer.

The antiangiogenic activity of a soluble fragment of the VEGFR extracellular domain

Vascular endothelial growth factor (VEGF) is a key regulator of pathological angiogenesis and vascular permeability and overexpressed by most solid tumors. VEGF receptor-2 (VEGFR-2 or kinase-insert domain-containing receptor as it is called in human, KDR) is a specific receptor of VEGF with a high binding affinity. A solube recombinant extracellular domain 1-3 of human VEGFR-2 (rKDR1-3) was expressed in Escherichia coli (E. Coli) and purified from the bacterial periplasmic extracts by immobilized metal affinity chromatography and anion exchange chromatography to inhibit the VEGF-induced angiogenesis. A surface plasmon resonance (SPR) technology was adopted to analyze the affinity and kinetics constant between rKDR1-3 and VEGF165. Under the given experimental conditions, the association rate constant Ka was 1.06×10(5)M(-1) S(-1), the dissociation rate Kd was 6.09×10(-3) S(-1), the dissociation constant KD was 5.74×10(-8)M. The effect of rKDR1-3 on VEGF-induced endothelial cell proliferation was studied using MTT assay, scratch-wound healing assay and chorioallantoic membrane (CAM) assay. The results showed that rKDR1-3 could inhibit neovascularization and serve as a useful drug candidate in research, diagnostics and therapy of cancer.

Lysyl oxidase-like-2 promotes tumour angiogenesis and is a potential therapeutic target in angiogenic tumours

Lysyl oxidase-like 2 (LOXL2), a secreted enzyme that catalyzes the cross-linking of collagen, plays an essential role in developmental angiogenesis. We found that administration of the LOXL2-neutralizing antibody AB0023 inhibited bFGF-induced angiogenesis in Matrigel plug assays and suppressed recruitment of angiogenesis promoting bone marrow cells. Small hairpin RNA-mediated inhibition of LOXL2 expression or inhibition of LOXL2 using AB0023 reduced the migration and network-forming ability of endothelial cells, suggesting that the inhibition of angiogenesis results from a direct effect on endothelial cells. To examine the effects of AB0023 on tumour angiogenesis, AB0023 was administered to mice bearing tumours derived from SKOV-3 ovarian carcinoma or Lewis lung carcinoma (LLC) cells. AB0023 treatment significantly reduced the microvascular density in these tumours but did not inhibit tumour growth. However, treatment of mice bearing SKOV-3-derived tumours with AB0023 also promoted increased coverage of tumour vessels with pericytes and reduced tumour hypoxia, providing evidence that anti-LOXL2 therapy results in the normalization of tumour blood vessels. In agreement with these data, treatment of mice bearing LLC-derived tumours with AB0023 improved the perfusion of the tumour-associated vessels as determined by ultrasonography. Improved perfusion and normalization of tumour vessels after treatment with anti-angiogenic agents were previously found to improve the delivery of chemotherapeutic agents into tumours and to result in an enhancement of chemotherapeutic efficiency. Indeed, treatment with AB0023 significantly enhanced the anti-tumourigenic effects of taxol. Our results suggest that inhibition of LOXL2 may prove beneficial for the treatment of angiogenic tumours.

Randomised, placebo-controlled, double-blind, parallel-group phase III study evaluating aflibercept in patients receiving first-line treatment with gemcitabine for metastatic pancreatic cancer

BACKGROUND

This phase III study investigated the addition of aflibercept to gemcitabine, in patients with advanced pancreatic cancer.

PATIENTS AND METHODS

Patients with metastatic pancreatic cancer were randomly assigned to receive either intravenous (i.v.) aflibercept, 4 mg/kg every 2 weeks, or matching placebo combined with gemcitabine, 1000 mg/m(2) i.v. weekly for 7 weeks out of 8, then weekly for 3 weeks out of 4 until progressive disease, unacceptable toxicity or withdrawal of consent. The primary objective was to demonstrate an improvement in overall survival (OS) between the treatment arms.

RESULTS

The study was stopped for futility following a planned interim analysis of OS in 427 randomised patients. With a median follow-up of 7.9 months, based on the 546 patients at study termination, median OS was 7.8 months in the gemcitabine plus placebo arm (n=275) versus 6.5 months in the gemcitabine plus aflibercept arm (n=271), which was not significant (hazard ratio 1.165, 95% confidence interval (CI) 0.921-1.473, p=0.2034). Median progression-free survival was 3.7 months in both arms. Treatment discontinuations due to adverse events were more frequent in the aflibercept than in the placebo-containing arm (23% versus 12%).

CONCLUSION

Adding aflibercept to gemcitabine did not improve OS in patients with metastatic pancreatic cancer.

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.

Peptide vaccines and targeting HER and VEGF proteins may offer a potentially new paradigm in cancer immunotherapy

The ErbB family (HER-1, HER-2, HER-3 and HER-4) of receptor tyrosine kinases has been the focus of cancer immunotherapeutic strategies while antiangiogenic therapies have focused on VEGF and its receptors VEGFR-1 and VEGFR-2. Agents targeting receptor tyrosine kinases in oncology include therapeutic antibodies to receptor tyrosine kinase ligands or the receptors themselves, and small-molecule inhibitors. Many of the US FDA-approved therapies targeting HER-2 and VEGF exhibit unacceptable toxicities, and show problems of efficacy, development of resistance and unacceptable safety profiles that continue to hamper their clinical progress. The combination of different peptide vaccines and peptidomimetics targeting specific molecular pathways that are dysregulated in tumors may potentiate anticancer immune responses, bypass immune tolerance and circumvent resistance mechanisms. The focus of this review is to discuss efforts in our laboratory spanning two decades of rationally developing peptide vaccines and therapeutics for breast cancer. This review highlights the prospective benefit of a new, untapped category of therapies biologically targeted to EGF receptor (HER-1), HER-2 and VEGF with potential peptide 'blockbusters' that could lay the foundation of a new paradigm in cancer immunotherapy by creating clinical breakthroughs for safe and efficacious cancer cures.

The VEGF pathway in cancer and disease: responses, resistance, and the path forward

Antiangiogenesis was proposed as a novel target for the treatment of cancer 40 years ago. Since the original hypothesis put forward by Judah Folkman in 1971, factors that mediate angiogenesis, their cellular targets, many of the pathways they signal, and inhibitors of the cytokines and receptors have been identified. Vascular endothelial growth factor (VEGF) is the most prominent among the angiogenic cytokines and is believed to play a central role in the process of neovascularization, both in cancer as well as other inflammatory diseases. This article reviews the biology of VEGF and its receptors, the use of anti-VEGF approaches in clinical disease, the toxicity of these therapies, and the resistance mechanisms that have limited the activity of these agents when used as monotherapy.

Phase I dose-escalation study of intravenous aflibercept administered in combination with irinotecan, 5-fluorouracil and leucovorin in patients with advanced solid tumours

BACKGROUND

To determine dose-limiting toxicities (DLTs), recommended phase II trial dose (RPTD), safety, preliminary antitumour activity and pharmacokinetics of intravenous aflibercept with irinotecan, 5-fluorouracil and leucovorin (LV5FU2).

PATIENTS AND METHODS

In this open-label study, 38 patients with advanced solid tumours received aflibercept 2, 4, 5, or 6 mg/kg on day 1, then irinotecan and LV5FU2 on days 1 and 2 every 2 weeks.

RESULTS

Two grade 3/4 aflibercept-associated DLTs occurred with 4 mg/kg: proteinuria lasting >2 weeks and acute nephrotic syndrome with thrombotic microangiopathy. Two DLTs with 5mg/kg (grade 3 stomatitis and grade 3 oesophagitis reflux) and three with 6 mg/kg (febrile neutropenia, grade 3 stomatitis and grade 3 abdominal pain) were considered related to concurrent chemotherapy and underlying disease. The most common grade 3/4 adverse events were neutropenia, hypertension and diarrhoea. Nine patients had partial responses, five with 4 mg/kg. Twenty-two patients had stable disease (five with 4 mg/kg), lasting >3 months in 17 patients. No anti-aflibercept antibodies were detected. Free aflibercept was in excess of bound in most patients on 4 mg/kg.

CONCLUSION

Based on pharmacokinetics, acceptable safety and encouraging antitumour activity, aflibercept 4 mg/kg was selected as the RPTD with irinotecan and LV5FU2 every 2 weeks.

AAV2-mediated gene transfer of VEGF-Trap with potent suppression of primary breast tumor growth and spontaneous pulmonary metastases by long-term expression

Vascular endothelial growth factor (VEGF) is an important signaling protein and a predominant mediator of angiogenesis in tumor growth and metastasis. Therefore, antagonism of the VEGF pathway results in inhibition of abnormal angiogenesis, then suppression of tumor growth and metastasis. VEGF-Trap, a high-affinity soluble decoy receptor, is currently in phase II clinical trails, and has demonstrated more efficacy in different types of solid tumors by intravenous injection every two weeks. In our study, we used recombinant AAV2 as a delivery vehicle to achieve long-lasting expression of VEGF Trap protein in a mouse model for the first time. We report that AAV2-VEGF-Trap can be safely administered and sustained expression in vivo via a single intravenously administration, simultaneously suppressing primary tumor growth and preventing the pulmonary metastases of 4T1 tumors. Decreased microvessel density and increased tumor cell apoptosis were observed in the treatment group. AAV2-VEGF-Trap can obviously decrease not only the concentration of VEGF in sera, but also the concentration of other angiogenic factors, such as aFGF, bFGF, angiopoietin-1 and others. These studies suggest that AAV-mediated long-term expression of VEGF-Trap is a useful and safe tool to block tumor progression and inhibit spontaneous pulmonary metastases.

Aflibercept: a Potent Vascular Endothelial Growth Factor Antagonist for Neovascular Age-Related Macular Degeneration and Other Retinal Vascular Diseases

Introduction

In the western hemisphere, age-related macular degeneration (AMD) is the leading cause of visual loss in the elderly. Currently approved therapies for AMD include argon laser, photodynamic therapy, and antivascular endothelial growth factor (VEGF) therapy. The index review discusses aflibercept (VEGF Trap-Eye) in the context of current anti-VEGF therapies for neovascular AMD and other retinal vascular diseases. It highlights important differences between VEGF Trap-Eye and currently used anti-VEGF therapies for neovascular AMD; and discusses the efficacy of these treatments utilizing information from landmark clinical trials.

Methods

A systematic search of literature was conducted on PubMed, Science Direct, and Scopus with no limitations of language or years of publication.

Results

Preclinical studies have shown that VEGF Trap-Eye binds to VEGF-A with a higher affinity than other anti-VEGF molecules; and that it also binds to placental growth factor (PlGF). In clinical trials, VEGF Trap-Eye has been shown to be as effective in the treatment of neovascular AMD as other anti-VEGF therapies and possibly to have a longer duration of drug activity.

Conclusion

VEGF Trap-Eye has enhanced the treatment options currently available for the management of neovascular AMD. The comparable efficacy of VEGF Trap-Eye (to other anti-VEGF agents) coupled with its longer dosing interval may decrease the number of annual office visits for patients with AMD and their caregivers.

Cardiac angiogenic imbalance leads to peripartum cardiomyopathy

Peripartum cardiomyopathy (PPCM) is an often fatal disease that affects pregnant women who are near delivery, and it occurs more frequently in women with pre-eclampsia and/or multiple gestation. The aetiology of PPCM, and why it is associated with pre-eclampsia, remain unknown. Here we show that PPCM is associated with a systemic angiogenic imbalance, accentuated by pre-eclampsia. Mice that lack cardiac PGC-1α, a powerful regulator of angiogenesis, develop profound PPCM. Importantly, the PPCM is entirely rescued by pro-angiogenic therapies. In humans, the placenta in late gestation secretes VEGF inhibitors like soluble FLT1 (sFLT1), and this is accentuated by multiple gestation and pre-eclampsia. This anti-angiogenic environment is accompanied by subclinical cardiac dysfunction, the extent of which correlates with circulating levels of sFLT1. Exogenous sFLT1 alone caused diastolic dysfunction in wild-type mice, and profound systolic dysfunction in mice lacking cardiac PGC-1α. Finally, plasma samples from women with PPCM contained abnormally high levels of sFLT1. These data indicate that PPCM is mainly a vascular disease, caused by excess anti-angiogenic signalling in the peripartum period. The data also explain how late pregnancy poses a threat to cardiac homeostasis, and why pre-eclampsia and multiple gestation are important risk factors for the development of PPCM.

eNOS deficiency acts through endothelin to aggravate sFlt-1-induced pre-eclampsia-like phenotype

Excess soluble fms-like tyrosine kinase 1 (sFlt-1) of vascular endothelial growth factor receptor 1 secreted from the placenta causes pre-eclampsia-like features by antagonizing vascular endothelial growth factor signaling, which can lead to reduced endothelial nitric oxide synthase (eNOS) activity; the effect of this concomitant decrease in eNOS activity is unknown. We tested whether the decrease in nitric oxide occurring in female mice lacking eNOS aggravates the pre-eclampsia-like phenotype induced by increased sFlt-1. Untreated eNOS-deficient female mice had higher BP than wild-type mice. Adenovirus-mediated overexpression of sFlt-1 increased systolic BP by approximately 27 mmHg and led to severe loss of fenestration of glomerular capillary endothelial cells in both eNOS-deficient and wild-type mice. However, only the eNOS-deficient sFlt-1 mice exhibited severe foot process effacement. Compared with wild-type sFlt-1 mice, eNOS-deficient sFlt-1 mice also showed markedly higher urinary albumin excretion (467±74 versus 174±23 μg/d), lower creatinine clearance (126±29 versus 452±63 μl/min), and more severe endotheliosis. Expression of preproendothelin-1 (ET-1) and its ET(A) receptor in the kidney was higher in eNOS-deficient sFlt-1 mice than in wild-type sFlt-1 mice. Furthermore, the selective ET(A) receptor antagonist ambrisentan attenuated the increases in BP and urinary albumin excretion and ameliorated endotheliosis in both wild-type and eNOS-deficient sFlt-1 mice. Ambrisentan improved creatinine clearance and podocyte effacement in eNOS-deficient sFlt-1 mice. In conclusion, reduced maternal eNOS/nitric oxide exacerbates the sFlt1-related pre-eclampsia-like phenotype through activation of the endothelin system.

Transcriptionally active syncytial aggregates in the maternal circulation may contribute to circulating soluble fms-like tyrosine kinase 1 in preeclampsia

The cardinal manifestations of the pregnancy-specific disorder preeclampsia, new-onset hypertension, and proteinuria that resolve with placental delivery have been linked to an extracellular protein made by the placenta, soluble fms-like tyrosine kinase 1 (sFlt1), that injures the maternal vasculature. However, the mechanisms by which sFlt1, which is heavily matrix bound, gain access to the systemic circulation remain unclear. Here we report that the preeclamptic placenta's outermost layer, the syncytiotrophoblast, forms abundant "knots" that are enriched with sFlt1 protein. These syncytial knots easily detach from the syncytiotrophoblast, resulting in free, multinucleated aggregates (50-150 μm diameter) that are loaded with sFlt1 protein and mRNA, are metabolically active, and are capable of de novo gene transcription and translation. At least 25% of the measurable sFlt1 in the third-trimester maternal plasma is bound to circulating placental microparticles. We conclude that detachment of syncytial knots from the placenta results in free, transcriptionally active syncytial aggregates that represent an autonomous source of sFlt1 delivery into the maternal circulation. The process of syncytial knot formation, shedding of syncytial aggregates, and appearance of placental microparticles in the maternal circulation appears to be greatly accelerated in preeclampsia and may contribute to the maternal vascular injury that characterizes this disorder.

Coronary collateral growth--back to the future

The coronary collateral circulation is critically important as an adaptation of the heart to prevent the damage from ischemic insults. In their native state, collaterals in the heart would be classified as part of the microcirculation, existing as arterial-arterial anastomotic connections in the range of 30 to 100 μM in diameter. However, these vessels also show a propensity to remodel into components of the macrocirculation and can become arteries larger than 1000 μM in diameter. This process of outward remodeling is critically important in the adaptation of the heart to ischemia because the resistance to blood flow is inversely related to the fourth power of the diameter of the vessel. Thus, an expansion of a vessel from 100 to 1000 μM would reduce resistance (in this part of the circuit) to a negligible amount and enable delivery of flow to the region at risk. Our goal in this review is to highlight the voids in understanding this adaptation to ischemia-the growth of the coronary collateral circulation. In doing so we discuss the controversies and unknown aspects of the causal factors that stimulate growth of the collateral circulation, the role of genetics, and the role of endogenous stem and progenitor cells in the context of the normal, physiological situation and under more pathological conditions of ischemic heart disease or with some of the underlying risk factors, e.g., diabetes. The major conclusion of this review is that there are many gaps in our knowledge of coronary collateral growth and this knowledge is critical before the potential of stimulating collateralization in the hearts of patients can be realized. This article is part of a Special Issue entitled "Coronary Blood Flow".

Epoxyeicosanoids stimulate multiorgan metastasis and tumor dormancy escape in mice

Epoxyeicosatrienoic acids (EETs) are small molecules produced by cytochrome P450 epoxygenases. They are lipid mediators that act as autocrine or paracrine factors to regulate inflammation and vascular tone. As a result, drugs that raise EET levels are in clinical trials for the treatment of hypertension and many other diseases. However, despite their pleiotropic effects on cells, little is known about the role of these epoxyeicosanoids in cancer. Here, using genetic and pharmacological manipulation of endogenous EET levels, we demonstrate that EETs are critical for primary tumor growth and metastasis in a variety of mouse models of cancer. Remarkably, we found that EETs stimulated extensive multiorgan metastasis and escape from tumor dormancy in several tumor models. This systemic metastasis was not caused by excessive primary tumor growth but depended on endothelium-derived EETs at the site of metastasis. Administration of synthetic EETs recapitulated these results, while EET antagonists suppressed tumor growth and metastasis, demonstrating in vivo that pharmacological modulation of EETs can affect cancer growth. Furthermore, inhibitors of soluble epoxide hydrolase (sEH), the enzyme that metabolizes EETs, elevated endogenous EET levels and promoted primary tumor growth and metastasis. Thus, our data indicate a central role for EETs in tumorigenesis, offering a mechanistic link between lipid signaling and cancer and emphasizing the critical importance of considering possible effects of EET-modulating drugs on cancer.