psi-697 and Venous-Thrombosis

Previously, we reported the discovery of PSI-697 (1a), a C-2 benzyl substituted quinoline salicylic acid-based P-selectin inhibitor. It is active in a variety of animal models of cardiovascular disease. Compound 1a has also been shown to be well tolerated and safe in healthy volunteers at doses of up to 1200 mg in a phase 1 single ascending dose study. However, its oral bioavailability was low. Our goal was to identify a back up compound with equal potency, increased solubility, and increased exposure. We expanded our structure-activity studies in this series by branching at the alpha position of the C-2 benzyl side chain and through modification of substituents on the carboxylic A-ring of the quinoline. This resulted in discovery of PSI-421 with marked improvement in aqueous solubility and pharmacokinetic properties. This compound has shown oral efficacy in animal models of arterial and venous injury and was selected as a preclinical development compound for potential treatment of such diseases as atherosclerosis and deep vein thrombosis.

Topics: Administration, Oral; Animals; Caco-2 Cells; Carotid Artery Injuries; Cell Membrane Permeability; Dogs; Drug Stability; Humans; Hydroxyquinolines; Leukocyte Rolling; Macaca fascicularis; Mice; Mice, Inbred C57BL; Microsomes, Liver; Models, Molecular; P-Selectin; Papio; Rats; Rats, Sprague-Dawley; Salicylates; Solubility; Structure-Activity Relationship; Venous Thrombosis

P-selectin plays a significant and well documented role in vascular disease by mediating leukocyte and platelet rolling and adhesion. This study characterizes the in vitro activity, pharmacokinetic properties, and the anti-inflammatory and antithrombotic efficacy of the orally active P-selectin small-molecule antagonist PSI-697 [2-(4-chlorobenzyl)-3-hydroxy-7,8,9,10-tetrahydrobenzo[h] quinoline-4-carboxylic acid; molecular mass, 367.83]. Biacore and cell-based assays were used to demonstrate the ability of PSI-697 to dose dependently inhibit the binding of human P-selectin to human P-selectin glycoprotein ligand-1, inhibiting 50% of binding at 50 to 125 microM. The pharmacokinetics of PSI-697 in rats were characterized by low clearance, short half-life, low volume of distribution, and moderate apparent oral bioavailability. A surgical inflammation model, using exteriorized rat cremaster venules, demonstrated that PSI-697 (50 mg/kg p.o.) significantly reduced the number of rolling leukocytes by 39% (P < 0.05) versus vehicle control. In a rat venous thrombosis model, PSI-697 (100 mg/kg p.o.) reduced thrombus weight by 18% (P < 0.05) relative to vehicle, without prolonging bleeding time. Finally, in a rat carotid injury model, PSI-697 (30 or 15 mg/kg p.o.) administered 1 h before arterial injury and once daily thereafter for 13 days resulted in dose-dependent decreases in intima/media ratios of 40.2% (P = 0.025) and 25.7% (P = 0.002) compared with vehicle controls. These data demonstrate the activity of PSI-697 in vitro and after oral administration in animal models of both arterial and venous injury and support the clinical evaluation of this novel antagonist of P-selectin in atherothrombotic and venous thrombotic indications.

Topics: Animals; Disease Models, Animal; HL-60 Cells; Humans; Hydroxyquinolines; Male; P-Selectin; Protein Binding; Rats; Rats, Sprague-Dawley; Vasculitis; Venous Thrombosis

P-selectin inhibition has been shown to decrease thrombogenesis in multiple animal species. In this study, we show that a novel oral small-molecule inhibitor of P-selectin, PSI-697, promotes thrombus resolution and decreases inflammation in a baboon model of venous thrombosis. Experimental groups consisted of the following: 1) primates receiving a single oral dose of PSI-697 (30 mg/kg) daily starting three days pre-iliac vein balloon occlusion, and continued for six days; 2) primates receiving a single treatment dose of a low-molecular-weight-heparin (LMWH) (1.5 mg/kg) daily starting one day pre-iliac balloon occlusion, and continued for six days; and 3) primates receiving a single oral dose of a vehicle control daily starting three days pre-iliac vein balloon occlusion, and continued for six days. Animals receiving PSI-697, although thrombosed after balloon deflation, demonstrated greater than 80% vein lumen opening over time, with no opening (0%) for vehicle control (p < 0.01). LMWH opening evident after balloon deflation slightly deteriorated over time compared to PSI-697. PSI-697 therapy also significantly decreased vein wall inflammation determined by magnetic resonance venography (MRV). Importantly, this beneficial opening occurred without measured anticoagulation. Animals receiving PSI-697 demonstrated significantly increased plasma D-dimer levels versus LMWH and control animals six hours post thrombus induction (p < 0.01). This study is the first to demonstrate the effectiveness of oral P-selectin inhibition to modify venous thrombogenesis, increase vein lumen opening, and decrease inflammation in a large animal model.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents; Anticoagulants; Blood Coagulation; Blood Coagulation Tests; Catheterization; Disease Models, Animal; Fibrin Fibrinogen Degradation Products; Fibrinolysis; Heparin, Low-Molecular-Weight; Hydroxyquinolines; Iliac Vein; Injections, Subcutaneous; Magnetic Resonance Angiography; Male; P-Selectin; Papio anubis; Time Factors; Ultrasonography, Doppler, Color; Vascular Patency; Venous Thrombosis

Vein wall injury after thrombosis is multifactorial but seems dependent on thrombus and local thrombotic and inflammatory mechanisms. We hypothesized that inhibition of vein wall injury through reduction of thrombotic and inflammatory events with P-selectin inhibition and/or low-molecular-weight heparin (LMWH) occurs independently of thrombus resolution in a rat model of venous thrombosis.. Male rats underwent inferior vena cava (IVC) stenosis (94.4% +/- 0.5% reduction in IVC diameter) to induce thrombosis. Rats were treated from 2 days after thrombosis until they were killed 7 days later. Groups consisted of (1) PSI-697, a P-selectin inhibitor (30 mg/kg; oral gavage daily); (2) LMWH-Lovenox (LOV; enoxaparin) 3 mg/kg subcutaneously daily; (3) PSI-697 (30 mg/kg; oral gavage daily) plus LOV 3 mg/kg subcutaneously daily (PSI + LOV); (4) and untreated controls. Evaluations included thrombus mass, vein wall tensiometry (stiffness [inverse of compliance]), intimal thickness scoring by light microscopy, vein wall inflammatory mediators by enzyme-linked immunosorbent assay, and vein wall inflammatory cells by histologic evaluation.. Thrombus mass was not reduced by any treatment. Animals treated with PSI-697 alone, LOV alone, or PSI + LOV demonstrated significant decreases in vein wall stiffness when compared with controls. The vein wall stiffness of the PSI-697-treated groups was also significantly lower than in the LOV-only group. Animals treated with PSI-697 showed a significantly decreased intimal thickness score when compared with vehicle control IVCs. Vein wall intimal thickening was also significantly decreased in animals treated with PSI-697 vs LOV. The PSI-697 and PSI + LOV groups manifested significant decreases in the immunoregulatory and inflammatory cytokine interleukin 13 as compared with controls and LOV. Vein wall monocyte chemotactic protein 1 levels were also significantly reduced in the PSI-697 and PSI + LOV groups vs control. Only PSI-697 significantly decreased vein wall levels of platelet-derived growth factor betabeta. Both the LOV and PSI + LOV groups had significant increases in vein wall monocytes and total inflammatory cells vs controls.. These data suggest that both LMWH and PSI-697 inhibit vein wall injury independently of thrombus mass. P-selectin inhibition seemed superior to LMWH in measured parameters of injury and mediator inhibition.

Topics: Animals; Anticoagulants; Constriction, Pathologic; Disease Models, Animal; Enoxaparin; Fibrosis; Hydroxyquinolines; Leukocytes; Monocyte Chemoattractant Proteins; Organic Chemicals; P-Selectin; Rats; Rats, Sprague-Dawley; Selectins; Tunica Intima; Vena Cava, Inferior; Venous Thrombosis