Aflibercept exhibits VEGF binding stoichiometry distinct from bevacizumab and does not support formation of immune-like complexes.

Anti-vascular endothelial growth factor (VEGF) therapies have improved clinical outcomes for patients with cancers and retinal vascular diseases. Three anti-VEGF agents, pegaptanib, ranibizumab, and aflibercept, are approved for ophthalmic indications, while bevacizumab is approved to treat colorectal, lung, and renal cancers, but is also used off-label to treat ocular vascular diseases. The efficacy of bevacizumab relative to ranibizumab in treating neovascular age-related macular degeneration has been assessed in several trials.

A novel inhibitor of p75-neurotrophin receptor improves functional outcomes in two models of traumatic brain injury.

The p75 neurotrophin receptor is important in multiple physiological actions including neuronal survival and neurite outgrowth during development, and after central nervous system injury. We have discovered a novel piperazine-derived compound, EVT901, which interferes with p75 neurotrophin receptor oligomerization through direct interaction with the first cysteine-rich domain of the extracellular region. Using ligand binding assays with cysteine-rich domains-fused p75 neurotrophin receptor, we confirmed that EVT901 interferes with oligomerization of full-length p75 neurotrophin receptor in a dose-dependent manner.

Regulator of G-protein signaling 18 controls both platelet generation and function.

RGS18 is a myeloerythroid lineage-specific regulator of G-protein signaling, highly expressed in megakaryocytes (MKs) and platelets. In the present study, we describe the first generation of a RGS18 knockout mouse model (RGS18-/-). Interesting phenotypic differences between RGS18-/- and wild-type (WT) mice were identified, and show that RGS18 plays a significant role in both platelet generation and function.

N-[6-(4-butanoyl-5-methyl-1H-pyrazol-1-yl)pyridazin-3-yl]-5-chloro-1-[2-(4-methylpiperazin-1-yl)-2-oxoethyl]-1H-indole-3-carboxamide (SAR216471), a novel intravenous and oral, reversible, and directly acting P2Y12 antagonist.

In the search of a potential backup for clopidogrel, we have initiated a HTS campaign designed to identify novel reversible P2Y12 antagonists. Starting from a hit with low micromolar binding activity, we report here the main steps of the optimization process leading to the identification of the preclinical candidate SAR216471. It is a potent, highly selective, and reversible P2Y12 receptor antagonist and by far the most potent inhibitor of ADP-induced platelet aggregation among the P2Y12 antagonists described in the literature.

Specific Inhibition of the VEGFR-3 Tyrosine Kinase by SAR131675 Reduces Peripheral and Tumor Associated Immunosuppressive Myeloid Cells.

Myeloid derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) represent prominent components in cancer progression. We previously showed that inhibition of the VEGFR-3 pathway by SAR131675 leads to reduction of TAM infiltration and tumor growth. Here, we found that treatment with SAR131675 prevents the accumulation of immunosuppressive blood and splenic MDSCs which express VEGFR-3, in 4T1 tumor bearing mice.

SAR131675, a potent and selective VEGFR-3-TK inhibitor with antilymphangiogenic, antitumoral, and antimetastatic activities.

SAR131675 is a potent and selective VEGFR-3 inhibitor. It inhibited VEGFR-3 tyrosine kinase activity and VEGFR-3 autophosphorylation in HEK cells with IC(50) values of 20 and 45 nmol/L, respectively. SAR131675 dose dependently inhibited the proliferation of primary human lymphatic cells, induced by the VEGFR-3 ligands VEGFC and VEGFD, with an IC(50) of about 20 nmol/L.

P2Y(4) nucleotide receptor: a novel actor in post-natal cardiac development.

Communication between endothelial cells and cardiomyocytes is critical for cardiac development and regeneration. However the mechanisms involved in these endothelial-cardiomyocyte interactions remain poorly understood. Nucleotides are released within the heart, especially under ischemia or pressure overload.

Hypoxia-inducible factor-1α mRNA: a new target for destabilization by tristetraprolin in endothelial cells.

Endothelial cells (ECs) are the primary sensors of variations in blood oxygen concentrations. They use the hypoxia-sensitive stabilization of the hypoxia-inducible factor-1α (HIF-1α) transcription factor to engage specific transcriptional programs in response to oxygen changes. The regulation of HIF-1α expression is well documented at the protein level, but much less is known about the control of its mRNA stability.

An improved method for specific and quantitative determination of the clopidogrel active metabolite isomers in human plasma.

Pharmacokinetic analyses of clopidogrel are hampered by the existence of multiple active metabolite isomers (H1 to H4) and their instability in blood. We sought to retest the pharmacodynamic activities of the four individual active metabolite isomers in vitro, with the ultimate aim of determining the isomers responsible for clopidogrel activity in vivo. In vitro activity was evaluated by measuring binding of [³³P]-2-methylthio-ADP on P2Y₁₂-expressing Chinese hamster ovary (CHO) cells and human platelets in platelet-rich plasma (PRP).

The active metabolite of Clopidogrel disrupts P2Y12 receptor oligomers and partitions them out of lipid rafts.

P2Y12, a G protein-coupled receptor that plays a central role in platelet activation has been recently identified as the receptor targeted by the antithrombotic drug, clopidogrel. In this study, we further deciphered the mechanism of action of clopidogrel and of its active metabolite (Act-Met) on P2Y12 receptors. Using biochemical approaches, we demonstrated the existence of homooligomeric complexes of P2Y12 receptors at the surface of mammalian cells and in freshly isolated platelets.

Soluble HLA-G1 inhibits angiogenesis through an apoptotic pathway and by direct binding to CD160 receptor expressed by endothelial cells.

HLA-G is a major histocompatibility complex class Ib molecule whose constitutive tissue distribution is restricted mainly to trophoblast cells at the maternal-fetal interface during pregnancy. In this study, we demonstrated the ability of the soluble HLA-G1 (sHLA-G1) isoform to inhibit fibroblast growth factor-2 (FGF2)-induced capillary-like tubule formation. Using a rabbit corneal neovascularization model, we further showed that sHLA-G1 inhibits FGF2-induced angiogenesis in vivo.

Neuropilin-2 interacts with VEGFR-2 and VEGFR-3 and promotes human endothelial cell survival and migration.

Neuropilin 2 (NRP2) is a receptor for the vascular endothelial growth factor (VEGF) and the semaphorin (SEMA) families, 2 unrelated ligand families involved in angiogenesis and neuronal guidance. NRP2 specifically binds VEGF-A and VEGF-C, although the biological relevance of these interactions in human endothelial cells is poorly understood. In this study, we show that both VEGF-A and VEGF-C induce the interaction of NRP2 with VEGFR-2.

Clopidogrel for the secondary prevention of stroke.

Patients suffering a transient ischaemic attack (TIA) or ischaemic stroke (IS) have a high risk of recurrence. The inhibition of platelet function is effective in the reduction of secondary vascular events in patients with TIA or stroke. This is true for acetylsalicylic acid (ASA), clopidogrel, ticlopidine and the combination of ASA plus slow-release dipyridamole.

Clopidogrel and ticlopidine: P2Y12 adenosine diphosphate-receptor antagonists for the prevention of atherothrombosis.

Ticlopidine and clopidogrel belong to the same chemical family of thienopyridine adenosine diphosphate (ADP)-receptor antagonists. They have shown their efficacy as platelet antiaggregant and antithrombotic agents in many animal models, both ex vivo and in vivo. Although ticlopidine was discovered more than 30 years ago, it was only recently that the mechanism of action of ADP-receptor antagonists was characterized in detail.

P2Y receptor antagonists in thrombosis.

The dual role of P2Y1 and P2Y12 receptors in platelet aggregation by ADP has been firmly established, based on the action of selective inhibitors, gene targeting in mice and human genetic evidence. Both of these receptor subtypes constitute targets for antithrombotic agents, and compounds with a dual action might also be of interest. However, the agents currently on the market (ticlopidine and clopidogrel), or known to be in development (cangrelor, AZD-6140 and prasugrel), all target the P2Y12 receptor.

Role of Gas6 receptors in platelet signaling during thrombus stabilization and implications for antithrombotic therapy.

Mechanisms regulating thrombus stabilization remain largely unknown. Here, we report that loss of any 1 of the Gas6 receptors (Gas6-Rs), i.e.

Revascularization of ischemic tissues by PDGF-CC via effects on endothelial cells and their progenitors.

The angiogenic mechanism and therapeutic potential of PDGF-CC, a recently discovered member of the VEGF/PDGF superfamily, remain incompletely characterized. Here we report that PDGF-CC mobilized endothelial progenitor cells in ischemic conditions; induced differentiation of bone marrow cells into ECs; and stimulated migration of ECs. Furthermore, PDGF-CC induced the differentiation of bone marrow cells into smooth muscle cells and stimulated their growth during vessel sprouting.

Heterodimerization with vascular endothelial growth factor receptor-2 (VEGFR-2) is necessary for VEGFR-3 activity.

VEGFR-3 is essential for vascular development and maintenance of lymphatic vessel's integrity. Little is known about its cooperative effect with other receptors of the same family. Contrary to VEGFR-2, stimulation of VEGFR-3 by VEGF-C and -D failed to enhance its phosphorylation either in HEK293T or in PAE cells.

Effect of fondaparinux on platelet activation in the presence of heparin-dependent antibodies: a blinded comparative multicenter study with unfractionated heparin.

Heparin-induced thrombocytopenia (HIT) is a complication of heparin therapy caused by antibodies against a complex of platelet factor 4 and heparin. Fondaparinux (Arixtra) is a new synthetic selective factor Xa inhibitor. We performed a serologic study to determine the cross-reactivity of HIT sera with fondaparinux.

P2Y12, a new platelet ADP receptor, target of clopidogrel.

Clopidogrel is a potent antithrombotic drug that inhibits ADP-induced platelet aggregation. The results of large clinical trials have demonstrated an overall benefit of clopidogrel over aspirin in the prevention of vascular ischemic events (myocardial infarction, stroke, vascular death) in patients with a history of symptomatic atherosclerotic disease. The antiaggregating effect of clopidogrel is attributed to an irreversible inhibition of ADP binding to a purinergic receptor present at the platelet surface.

The antiaggregating activity of clopidogrel is not affected by N-acetyl L-cysteine.

N-acetyl L-cysteine (NAC) is widely used to treat obstructive bronchopulmonary diseases. It has thiol reactive properties, accounting for its mucolytic activity. Clopidogrel is a potent antithrombotic compound, metabolised by the liver which generates an active metabolite containing a thiol reactive group, responsible for an irreversible interaction with the platelet P2Y(12) ADP receptor.

Pharmacological characterization of the human P2Y13 receptor.

The P2Y13 receptor has recently been identified as a new P2Y receptor sharing a high sequence homology with the P2Y12 receptor as well as similar functional properties: coupling to Gi and responsiveness to ADP (Communi et al., 2001). In the present study, the pharmacology of the P2Y13 receptor and its differences with that of the P2Y12 receptor have been further characterized in 1321N1 cells (binding of [33P]2-methylthio-ADP (2MeSADP) and of GTPgamma[35S]), 1321N1 cells coexpressing Galpha16 [AG32 cells: inositol trisphosphate (IP3) measurement, binding of GTPgamma[35S]) and Chinese hamster ovary (CHO)-K1 cells (cAMP assay)].

Effect of clopidogrel administration to healthy volunteers on platelet phosphorylation events triggered by ADP.

Unlabelled: The action of clopidogrel on platelet receptors was analysed using platelets obtained from 11 healthy volunteers given 75 mg of clopidogrel daily for 8 d. Samples of blood were taken before treatment and after 8 d of medication. Determination of 2-methylthioadenosine diphosphate trisodium (2MesADP)-induced platelet aggregation, serine/threonine and tyrosine phosphorylations were performed in the absence or presence of the P2Y1-receptor-specific antagonist: adenosine 3'-phosphate 5'-phosphate (A3P5P) or the strong inhibitor of GPIIb/IIIa activation: SR121566.