Pulmonary emphysema, a significant global health problem, is characterized by a loss of alveolar structures. Because VEGF is a trophic factor required for the survival of endothelial cells and is abundantly expressed in the lung, we hypothesized that chronic blockade of VEGF receptors could induce alveolar cell apoptosis and emphysema. Chronic treatment of rats with the VEGF receptor blocker SU5416 led to enlargement of the air spaces, indicative of emphysema. The VEGF receptor inhibitor SU5416 induced alveolar septal cell apoptosis but did not inhibit lung cell proliferation. Viewed by angiography, SU5416-treated rat lungs showed a pruning of the pulmonary arterial tree, although we observed no lung infiltration by inflammatory cells or fibrosis. SU5416 treatment led to a decrease in lung expression of VEGF receptor 2 (VEGFR-2), phosphorylated VEGFR-2, and Akt-1 in the complex with VEGFR-2. Treatment with the caspase inhibitor Z-Asp-CH(2)-DCB prevented SU5416-induced septal cell apoptosis and emphysema development. These findings suggest that VEGF receptor signaling is required for maintenance of the alveolar structures and, further, that alveolar septal cell apoptosis contributes to the pathogenesis of emphysema.

Vascular endothelial growth factor (VEGF) is an angiogenic protein with therapeutic potential in ischemic disorders, including stroke. VEGF confers neuroprotection and promotes neurogenesis and cerebral angiogenesis, but the manner in which these effects may interact in the ischemic brain is poorly understood. We produced focal cerebral ischemia by middle cerebral artery occlusion for 90 minutes in the adult rat brain and measured infarct size, neurological function, BrdU labeling of neuroproliferative zones, and vWF-immunoreactive vascular profiles, without and with intracerebroventricular administration of VEGF on days 1-3 of reperfusion. VEGF reduced infarct size, improved neurological performance, enhanced the delayed survival of newborn neurons in the dentate gyrus and subventricular zone, and stimulated angiogenesis in the striatal ischemic penumbra, but not the dentate gyrus. We conclude that in the ischemic brain VEGF exerts an acute neuroprotective effect, as well as longer latency effects on survival of new neurons and on angiogenesis, and that these effects appear to operate independently. VEGF may, therefore, improve histological and functional outcome from stroke through multiple mechanisms.

Fibroblast growth factors (FGFs) are a family of heparin-binding growth factors. FGFs exert their pro-angiogenic activity by interacting with various endothelial cell surface receptors, including tyrosine kinase receptors, heparan-sulfate proteoglycans, and integrins. Their activity is modulated by a variety of free and extracellular matrix-associated molecules. Also, the cross-talk among FGFs, vascular endothelial growth factors (VEGFs), and inflammatory cytokines/chemokines may play a role in the modulation of blood vessel growth in different pathological conditions, including cancer. Indeed, several experimental evidences point to a role for FGFs in tumor growth and angiogenesis. This review will focus on the relevance of the FGF/FGF receptor system in adult angiogenesis and its contribution to tumor vascularization.

OBJECTIVE

The 2-year, phase III trial designated Anti-vascular endothelial growth factor (VEGF) Antibody for the Treatment of Predominantly Classic Choroidal Neovascularization (CNV) in Age-related Macular Degeneration (ANCHOR) compared ranibizumab with verteporfin photodynamic therapy (PDT) in treating predominantly classic CNV.

METHODS

Multicenter, international, randomized, double-masked, active-treatment-controlled clinical trial.

METHODS

Patients with predominantly classic, subfoveal CNV not previously treated with PDT or antiangiogenic drugs.

METHODS

Patients were randomized 1:1:1 to verteporfin PDT plus monthly sham intraocular injection or to sham verteporfin PDT plus monthly intravitreal ranibizumab (0.3 mg or 0.5 mg) injection. The need for PDT (active or sham) retreatment was evaluated every 3 months using fluorescein angiography (FA).

METHODS

The primary, intent-to-treat efficacy analysis was at 12 months, with continued measurements to month 24. Key measures included the percentage losing <15 letters from baseline visual acuity (VA) score (month 12 primary efficacy outcome measure), percentage gaining>>or=15 letters from baseline, and mean change over time in VA score and FA-assessed lesion characteristics. Adverse events were monitored.

RESULTS

Of 423 patients (143 PDT, 140 each in the 2 ranibizumab groups), the majority >>or=77% in each group) completed the 2-year study. Consistent with results at month 12, at month 24 the VA benefit from ranibizumab was statistically significant (P<0.0001 vs. PDT) and clinically meaningful: 89.9% to 90.0% of ranibizumab-treated patients had lost <15 letters from baseline (vs. 65.7% of PDT patients); 34% to 41.0% had gained>>or=15 letters (vs. 6.3% of PDT group); and, on average, VA was improved from baseline by 8.1 to 10.7 letters (vs. a mean decline of 9.8 letters in PDT group). Changes in lesion anatomic characteristics on FA also favored ranibizumab (all comparisons P<0.0001 vs. PDT). Overall, there was no imbalance among groups in rates of serious ocular and nonocular adverse events. In the pooled ranibizumab groups, 3 of 277 (1.1%) patients developed presumed endophthalmitis in the study eye (rate per injection = 3/5921 [0.05%]).

CONCLUSIONS

In this 2-year study, ranibizumab provided greater clinical benefit than verteporfin PDT in patients with age-related macular degeneration with new-onset, predominantly classic CNV. Rates of serious adverse events were low.

BACKGROUND

Proprietary or commercial disclosure may be found after the references.

BACKGROUND

Bevacizumab plus fluoropyrimidine-based chemotherapy is standard treatment for first-line and bevacizumab-naive second-line metastatic colorectal cancer. We assessed continued use of bevacizumab plus standard second-line chemotherapy in patients with metastatic colorectal cancer progressing after standard first-line bevacizumab-based treatment.

METHODS

In an open-label, phase 3 study in 220 centres in Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, the Netherlands, Norway, Portugal, Saudi Arabia, Spain, Sweden, and Switzerland, patients (aged ≥18 years) with unresectable, histologically confirmed metastatic colorectal cancer progressing up to 3 months after discontinuing first-line bevacizumab plus chemotherapy were randomly assigned in a 1:1 ratio to second-line chemotherapy with or without bevacizumab 2·5 mg/kg per week equivalent (either 5 mg/kg every 2 weeks or 7·5 mg/kg every 3 weeks, intravenously). The choice between oxaliplatin-based or irinotecan-based second-line chemotherapy depended on the first-line regimen (switch of chemotherapy). A combination of a permuted block design and the Pocock and Simon minimisation algorithm was used for the randomisation. The primary endpoint was overall survival, analysed by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00700102.

RESULTS

Between Feb 1, 2006, and June 9, 2010, 409 (50%) patients were assigned to bevacizumab plus chemotherapy and 411 (50%) to chemotherapy alone. Median follow-up was 11·1 months (IQR 6·4-15·6) in the bevacizumab plus chemotherapy group and 9·6 months (5·4-13·9) in the chemotherapy alone group. Median overall survival was 11·2 months (95% CI 10·4-12·2) for bevacizumab plus chemotherapy and 9·8 months (8·9-10·7) for chemotherapy alone (hazard ratio 0·81, 95% CI 0·69-0·94; unstratified log-rank test p=0·0062). Grade 3-5 bleeding or haemorrhage (eight [2%] vs one [<1%]), gastrointestinal perforation (seven [2%] vs three [<1%]), and venous thromboembolisms (19 [5%] vs 12 [3%]) were more common in the bevacizumab plus chemotherapy group than in the chemotherapy alone group. The most frequently reported grade 3-5 adverse events were neutropenia (65 [16%] in the bevacizumab and chemotherapy group vs 52 [13%] in the chemotherapy alone group), diarrhoea (40 [10%] vs 34 [8%], respectively), and asthenia (23 [6%] vs 17 [4%], respectively). Treatment-related deaths were reported for four patients in the bevacizumab plus chemotherapy group and three in the chemotherapy alone group.

CONCLUSIONS

Maintenance of VEGF inhibition with bevacizumab plus standard second-line chemotherapy beyond disease progression has clinical benefits in patients with metastatic colorectal cancer. This approach is also being investigated in other tumour types, including metastatic breast and non-small cell lung cancers.

BACKGROUND

F Hoffmann-La Roche.

Brain metastasis frequently occurs in individuals with cancer and is often fatal. We used multiphoton laser scanning microscopy to image the single steps of metastasis formation in real time. Thus, it was possible to track the fate of individual metastasizing cancer cells in vivo in relation to blood vessels deep in the mouse brain over minutes to months. The essential steps in this model were arrest at vascular branch points, early extravasation, persistent close contacts to microvessels and perivascular growth by vessel cooption (melanoma) or early angiogenesis (lung cancer). Inefficient steps differed between the tumor types. Long-term dormancy was only observed for single perivascular cancer cells, some of which moved continuously. Vascular endothelial growth factor-A (VEGF-A) inhibition induced long-term dormancy of lung cancer micrometastases by preventing angiogenic growth to macrometastases. The ability to image the establishment of brain metastases in vivo provides new insights into their evolution and response to therapies.

Endothelial cells control the passage of plasma constituents and circulating cells from blood to the underlying tissues. This specialized function is lost or impaired in several pathological conditions - including inflammation, sepsis, ischemia and diabetes - which leads to severe, and sometimes fatal, organ dysfunction. Endothelial permeability is regulated in part by the dynamic opening and closure of cell-cell adherens junctions (AJs). In endothelial cells, AJs are largely composed of vascular endothelial cadherin (VE-cadherin), an endothelium-specific member of the cadherin family of adhesion proteins that binds, via its cytoplasmic domain, to several protein partners, including p120, beta-catenin and plakoglobin. Endogenous pathways that increase vascular permeability affect the function and organization of VE-cadherin and other proteins at AJs in diverse ways. For instance, several factors, including vascular endothelial growth factor (VEGF), induce the tyrosine phosphorylation of VE-cadherin, which accompanies an increase in vascular permeability and leukocyte diapedesis; in addition, the internalization and cleavage of VE-cadherin can cause AJs to be dismantled. From the knowledge of how AJ organization can be modulated, it is possible to formulate several pharmacological strategies to control the barrier function of the endothelium. We discuss the possible use of inhibitors of SRC and other kinases, of agents that increase cAMP levels, and of inhibitors of lytic enzymes as pharmacological tools for decreasing endothelial permeability.

Vascular endothelial growth factor (VEGF) is a homodimeric glycoprotein with a molecular weight of approximately 45 kDa. It is the key mediator of angiogenesis (the formation of new blood vessels), and binds two VEGF receptors (VEGF receptor-1 and VEGF receptor-2), which are expressed on vascular endothelial cells. In healthy humans, VEGF promotes angiogenesis in embryonic development and is important in wound healing in adults. VEGF is the key mediator of angiogenesis in cancer, in which it is up-regulated by oncogene expression, a variety of growth factors and also hypoxia. Angiogenesis is essential for cancer development and growth: before a tumor can grow beyond 1-2 mm, it requires blood vessels for nutrients and oxygen. The production of VEGF and other growth factors by the tumor results in the 'angiogenic switch', where new vasculature is formed in and around the tumor, allowing it to grow exponentially. Tumor vasculature formed under the influence of VEGF is structurally and functionally abnormal. Blood vessels are irregularly shaped, tortuous, have dead ends and are not organized into venules, arterioles and capillaries. They are also leaky and hemorrhagic, which leads to high interstitial pressure. These characteristics mean that tumor blood flow is suboptimal, resulting in hypoxia and further VEGF production. This central role of VEGF in the production of tumor vasculature makes it a rational target for anticancer therapy.

VEGF is a secreted mitogen associated with angiogenesis and is also a potent vascular permeability factor. The biological role of VEGF in the ischemic brain remains unknown. This study was undertaken to investigate whether VEGF enhances cerebral microvascular perfusion and increases blood-brain barrier (BBB) leakage in the ischemic brain. Using magnetic resonance imaging (MRI), three-dimensional laser-scanning confocal microscope, and functional neurological tests, we measured the effects of administrating recombinant human VEGF(165) (rhVEGF(165)) on angiogenesis, functional neurological outcome, and BBB leakage in a rat model of focal cerebral embolic ischemia. Late (48 hours) administration of rhVEGF(165) to the ischemic rats enhanced angiogenesis in the ischemic penumbra and significantly improved neurological recovery. However, early postischemic (1 hour) administration of rhVEGF(165) to ischemic rats significantly increased BBB leakage, hemorrhagic transformation, and ischemic lesions. Administration of rhVEGF(165) to ischemic rats did not change BBB leakage and cerebral plasma perfusion in the contralateral hemisphere. Our results indicate that VEGF can markedly enhance angiogenesis in the ischemic brain and reduce neurological deficits during stroke recovery and that inhibition of VEGF at the acute stage of stroke may reduce the BBB permeability and the risk of hemorrhagic transformation after focal cerebral ischemia.

No growth factors specific for the lymphatic vascular system have yet been described. Vascular endothelial growth factor (VEGF) regulates vascular permeability and angiogenesis, but does not promote lymphangiogenesis. Overexpression of VEGF-C, a ligand of the VEGF receptors VEGFR-3 and VEGFR-2, in the skin of transgenic mice resulted in lymphatic, but not vascular, endothelial proliferation and vessel enlargement. Thus, VEGF-C induces selective hyperplasia of the lymphatic vasculature, which is involved in the draining of interstitial fluid and in immune function, inflammation, and tumor metastasis. VEGF-C may play a role in disorders involving the lymphatic system and may be of potential use in therapeutic lymphangiogenesis.

Recent studies suggest that statins can function to protect the vasculature in a manner that is independent of their lipid-lowering activity. We show here that statins rapidly activate the protein kinase Akt/PKB in endothelial cells. Accordingly, simvastatin enhanced phosphorylation of the endogenous Akt substrate endothelial nitric oxide synthase (eNOS), inhibited apoptosis and accelerated vascular structure formation in vitro in an Akt-dependent manner. Similar to vascular endothelial growth factor (VEGF) treatment, both simvastatin administration and enhanced Akt signaling in the endothelium promoted angiogenesis in ischemic limbs of normocholesterolemic rabbits. Therefore, activation of Akt represents a mechanism that can account for some of the beneficial side effects of statins, including the promotion of new blood vessel growth.

The VEGF/VPF (vascular endothelial growth factor/vascular permeability factor) ligands and receptors are crucial regulators of vasculogenesis, angiogenesis, lymphangiogenesis and vascular permeability in vertebrates. VEGF-A, the prototype VEGF ligand, binds and activates two tyrosine kinase receptors: VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). VEGFR1, which occurs in transmembrane and soluble forms, negatively regulates vasculogenesis and angiogenesis during early embryogenesis, but it also acts as a positive regulator of angiogenesis and inflammatory responses, playing a role in several human diseases such as rheumatoid arthritis and cancer. The soluble VEGFR1 is overexpressed in placenta in preeclampsia patients. VEGFR2 has critical functions in physiological and pathological angiogenesis through distinct signal transduction pathways regulating proliferation and migration of endothelial cells. VEGFR3, a receptor for the lymphatic growth factors VEGF-C and VEGF-D, but not for VEGF-A, regulates vascular and lymphatic endothelial cell function during embryogenesis. Loss-of-function variants of VEGFR3 have been identified in lymphedema. Formation of tumor lymphatics may be stimulated by tumor-produced VEGF-C, allowing increased spread of tumor metastases through the lymphatics. Mapping the signaling system of these important receptors may provide the knowledge necessary to suppress specific signaling pathways in major human diseases.

Matrix metalloprotease type 9 (MMP-9) has been functionally implicated in VEGF activation, the induction and maintenance of chronic angiogenesis, and early stage tumor growth in a number of mouse models of cancer. In this article, we have identified two inflammatory cell types that are major sources of MMP-9 in the angiogenic stages of pancreatic islet carcinogenesis that unfold in RIP1-Tag2 transgenic mice. MMP-9-expressing neutrophils were predominantly found inside angiogenic islet dysplasias and tumors, whereas MMP-9-expressing macrophages were localized along the periphery of such lesions. Transient depletion of neutrophils significantly suppressed VEGF:VEGF-receptor association, a signature of MMP-9 activity, and markedly reduced the frequency of initial angiogenic switching in dysplasias. Thus infiltrating neutrophils can play a crucial role in activating angiogenesis in a previously quiescent tissue vasculature during the early stages of carcinogenesis.

Angiogenesis, the growth of new blood vessels from pre-existing vasculature, is a key process in several pathological conditions, including tumour growth and age-related macular degeneration. Vascular endothelial growth factors (VEGFs) stimulate angiogenesis and lymphangiogenesis by activating VEGF receptor (VEGFR) tyrosine kinases in endothelial cells. VEGFR-3 (also known as FLT-4) is present in all endothelia during development, and in the adult it becomes restricted to the lymphatic endothelium. However, VEGFR-3 is upregulated in the microvasculature of tumours and wounds. Here we demonstrate that VEGFR-3 is highly expressed in angiogenic sprouts, and genetic targeting of VEGFR-3 or blocking of VEGFR-3 signalling with monoclonal antibodies results in decreased sprouting, vascular density, vessel branching and endothelial cell proliferation in mouse angiogenesis models. Stimulation of VEGFR-3 augmented VEGF-induced angiogenesis and sustained angiogenesis even in the presence of VEGFR-2 (also known as KDR or FLK-1) inhibitors, whereas antibodies against VEGFR-3 and VEGFR-2 in combination resulted in additive inhibition of angiogenesis and tumour growth. Furthermore, genetic or pharmacological disruption of the Notch signalling pathway led to widespread endothelial VEGFR-3 expression and excessive sprouting, which was inhibited by blocking VEGFR-3 signals. Our results implicate VEGFR-3 as a regulator of vascular network formation. Targeting VEGFR-3 may provide additional efficacy for anti-angiogenic therapies, especially towards vessels that are resistant to VEGF or VEGFR-2 inhibitors.

Little is known about how the initial endothelial plexus is remodelled into a mature and functioning vascular network. Studying postnatal remodelling of the retina vasculature, we show that a critical step in vascular maturation, namely pericyte recruitment, proceeds by outmigration of cells positive for (alpha)-smooth muscle actin from arterioles and that coverage of primary and smaller branches lags many days behind formation of the endothelial plexus. The transient existence of a pericyte-free endothelial plexus coincides temporally and spatially with the process of hyperoxia-induced vascular pruning, which is a mechanism for fine tuning of vascular density according to available oxygen. Acquisition of a pericyte coating marks the end of this plasticity window. To substantiate that association with pericytes stabilizes the vasculature, endothelial-pericyte associations were disrupted by intraocular injection of PDGF-BB. Ectopic PDGF-BB caused the detachment of PDGF-beta receptor-positive pericytes from newly coated vessels, presumably through interference with endogenous cues, but had no effect on mature vessels. Disruption of endothelial-pericyte associations resulted in excessive regression of vascular loops and abnormal remodelling. Conversely, intraocular injection of VEGF accelerated pericyte coverage of the preformed endothelial plexus, thereby revealing a novel function of this pleiotropic angiogenic growth factor. These findings also provide a cellular basis for clinical observations that vascular regression in premature neonates subjected to oxygen therapy [i.e. in retinopathy of prematurity] drops precipitously upon maturation of retina vessels and a mechanistic explanation to our previous findings that VEGF can rescue immature vessels from hyperoxia-induced regression.

Aptamers are oligonucleotide ligands that are selected for high-affinity binding to molecular targets. Pegaptanib sodium (Macugen; Eyetech Pharmaceuticals/Pfizer) is an RNA aptamer directed against vascular endothelial growth factor (VEGF)-165, the VEGF isoform primarily responsible for pathological ocular neovascularization and vascular permeability. After nearly a decade of preclinical development to optimize and characterize its biological effects, pegaptanib was shown in clinical trials to be effective in treating choroidal neovascularization associated with age-related macular degeneration. Pegaptanib therefore has the notable distinction of being the first aptamer therapeutic approved for use in humans, paving the way for future aptamer applications.

Metastasis to local lymph nodes via the lymphatic vessels is a common step in the spread of solid tumors. To investigate the molecular mechanisms underlying the spread of cancer by the lymphatics, we examined the ability of vascular endothelial growth factor (VEGF)-D, a ligand for the lymphatic growth factor receptor VEGFR-3/Flt-4, to induce formation of lymphatics in a mouse tumor model. Staining with markers specific for lymphatic endothelium demonstrated that VEGF-D induced the formation of lymphatics within tumors. Moreover, expression of VEGF-D in tumor cells led to spread of the tumor to lymph nodes, whereas expression of VEGF, an angiogenic growth factor which activates VEGFR-2 but not VEGFR-3, did not. VEGF-D also promoted tumor angiogenesis and growth. Lymphatic spread induced by VEGF-D could be blocked with an antibody specific for VEGF-D. This study demonstrates that lymphatics can be established in solid tumors and implicates VEGF family members in determining the route of metastatic spread.

Blood vessel networks expand in a 2-step process that begins with vessel sprouting and is followed by vessel anastomosis. Vessel sprouting is induced by chemotactic gradients of the vascular endothelial growth factor (VEGF), which stimulates tip cell protrusion. Yet it is not known which factors promote the fusion of neighboring tip cells to add new circuits to the existing vessel network. By combining the analysis of mouse mutants defective in macrophage development or VEGF signaling with live imaging in zebrafish, we now show that macrophages promote tip cell fusion downstream of VEGF-mediated tip cell induction. Macrophages therefore play a hitherto unidentified and unexpected role as vascular fusion cells. Moreover, we show that there are striking molecular similarities between the pro-angiogenic tissue macrophages essential for vascular development and those that promote the angiogenic switch in cancer, including the expression of the cell-surface proteins TIE2 and NRP1. Our findings suggest that tissue macrophages are a target for antiangiogenic therapies, but that they could equally well be exploited to stimulate tissue vascularization in ischemic disease.

OBJECTIVE

Bevacizumab is an antibody that binds to vascular endothelial growth factor (VEGF) and has activity in metastatic renal cell carcinoma (RCC). Interferon alfa (IFN) is a historic standard first-line treatment for RCC. A prospective, randomized phase III trial of bevacizumab plus IFN versus IFN monotherapy was conducted.

METHODS

Patients with previously untreated, metastatic clear-cell RCC were randomly assigned to receive either bevacizumab (10 mg/kg intravenously every 2 weeks) plus IFN (9 million U subcutaneously three times weekly) or the same dose and schedule of IFN monotherapy in a multicenter phase III trial. The primary end point was overall survival (OS). Secondary end points were progression-free survival (PFS), objective response rate (ORR), and safety.

RESULTS

Between October 2003 and July 2005, 732 patients were enrolled. The prespecified stopping rule for OS has not yet been reached. The median PFS was 8.5 months in patients receiving bevacizumab plus IFN (95% CI, 7.5 to 9.7 months) versus 5.2 months (95% CI, 3.1 to 5.6 months) in patients receiving IFN monotherapy (log-rank P < .0001). The adjusted hazard ratio was 0.71 (95% CI, 0.61 to 0.83; P < .0001). Bevacizumab plus IFN had a higher ORR as compared with IFN (25.5% [95% CI, 20.9% to 30.6%] v 13.1% [95% CI, 9.5% to 17.3%]; P < .0001). Overall toxicity was greater for bevacizumab plus IFN, including significantly more grade 3 hypertension (9% v 0%), anorexia (17% v 8%), fatigue (35% v 28%), and proteinuria (13% v 0%).

CONCLUSIONS

Bevacizumab plus IFN produces a superior PFS and ORR in untreated patients with metastatic RCC as compared with IFN monotherapy. Toxicity is greater in the combination therapy arm.

Features that distinguish tumor vasculatures from normal blood vessels are sought to enable the destruction of preformed tumor vessels. We show that blood vessels in both a xenografted tumor and primary human tumors contain a sizable fraction of immature blood vessels that have not yet recruited periendothelial cells. These immature vessels are selectively obliterated as a consequence of vascular endothelial growth factor (VEGF) withdrawal. In a xenografted glioma, the selective vulnerability of immature vessels to VEGF loss was demonstrated by downregulating VEGF transgene expression using a tetracycline-regulated expression system. In human prostate cancer, the constitutive production of VEGF by the glandular epithelium was suppressed as a consequence of androgen-ablation therapy. VEGF loss led, in turn, to selective apoptosis of endothelial cells in vessels devoid of periendothelial cells. These results suggest that the unique dependence on VEGF of blood vessels lacking periendothelial cells can be exploited to reduce an existing tumor vasculature.

Rheumatoid arthritis (RA), a systemic disease, is characterized by a chronic inflammatory reaction in the synovium of joints and is associated with degeneration of cartilage and erosion of juxta-articular bone. Many pro-inflammatory cytokines including TNF alpha, chemokines, and growth factors are expressed in diseased joints. The rationale that TNF alpha played a central role in regulating these molecules, and their pathophysiological potential, was initially provided by the demonstration that anti-TNF alpha antibodies added to in vitro cultures of a representative population of cells derived from diseased joints inhibited the spontaneous production of IL-1 and other pro-inflammatory cytokines. Systemic administration of anti-TNF alpha antibody or sTNFR fusion protein to mouse models of RA was shown to be anti-inflammatory and joint protective. Clinical investigations in which the activity of TNF alpha in RA patients was blocked with intravenously administered infliximab, a chimeric anti-TNF alpha monoclonal antibody (mAB), has provided evidence that TNF regulates IL-6, IL-8, MCP-1, and VEGF production, recruitment of immune and inflammatory cells into joints, angiogenesis, and reduction of blood levels of matrix metalloproteinases-1 and -3. Randomized, placebo-controlled, multi-center clinical trials of human TNF alpha inhibitors have demonstrated their consistent and remarkable efficacy in controlling signs and symptoms, with a favorable safety profile, in approximately two thirds of patients for up to 2 years, and their ability to retard joint damage. Infliximab (a mAB), and etanercept (a sTNF-R-Fc fusion protein) have been approved by regulatory authorities in the United States and Europe for treating RA, and they represent a significant new addition to available therapeutic options.

Ten antiangiogenic drugs targeting VEGF or its receptors are approved for cancer treatment. However, these agents, intended to block tumors' blood supply, may cause hypoxia, which may fuel tumor progression and treatment resistance. Emerging clinical data suggest that patients whose tumor perfusion or oxygenation increases in response to these agents may actually survive longer. Hence, strategies aimed at alleviating tumor hypoxia while improving perfusion may enhance the outcome of radiotherapy, chemotherapy, and immunotherapy. Here I summarize lessons learned from preclinical and clinical studies over the past decade and propose strategies for improving antiangiogenic therapy outcomes for malignant and nonmalignant diseases.

Custom-made zinc-finger nucleases (ZFNs) can induce targeted genome modifications with high efficiency in cell types including Drosophila, C. elegans, plants, and humans. A bottleneck in the application of ZFN technology has been the generation of highly specific engineered zinc-finger arrays. Here we describe OPEN (Oligomerized Pool ENgineering), a rapid, publicly available strategy for constructing multifinger arrays, which we show is more effective than the previously published modular assembly method. We used OPEN to construct 37 highly active ZFN pairs which induced targeted alterations with high efficiencies (1%-50%) at 11 different target sites located within three endogenous human genes (VEGF-A, HoxB13, and CFTR), an endogenous plant gene (tobacco SuRA), and a chromosomally integrated EGFP reporter gene. In summary, OPEN provides an "open-source" method for rapidly engineering highly active zinc-finger arrays, thereby enabling broader practice, development, and application of ZFN technology for biological research and gene therapy.

The association of pericytes (PCs) to newly formed blood vessels has been suggested to regulate endothelial cell (EC) proliferation, survival, migration, differentiation, and vascular branching. Here, we addressed these issues using PDGF-B-- and PDGF receptor-beta (PDGFR-beta)--deficient mice as in vivo models of brain angiogenesis in the absence of PCs. Quantitative morphological analysis showed that these mutants have normal microvessel density, length, and number of branch points. However, absence of PCs correlates with endothelial hyperplasia, increased capillary diameter, abnormal EC shape and ultrastructure, changed cellular distribution of certain junctional proteins, and morphological signs of increased transendothelial permeability. Brain endothelial hyperplasia was observed already at embryonic day (E) 11.5 and persisted throughout development. From E 13.5, vascular endothelial growth factor-A (VEGF-A) and other genes responsive to metabolic stress became upregulated, suggesting that the abnormal microvessel architecture has systemic metabolic consequences. VEGF-A upregulation correlated temporally with the occurrence of vascular abnormalities in the placenta and dilation of the heart. Thus, although PC deficiency appears to have direct effects on EC number before E 13.5, the subsequent increased VEGF-A levels may further abrogate microvessel architecture, promote vascular permeability, and contribute to formation of the edematous phenotype observed in late gestation PDGF-B and PDGFR-beta knock out embryos.