Free Tissue Factor Pathway Inhibitor Research Articles

Relationship between plasma tissue Factor Pathway Inhibitor (TFPI) levels, thrombin generation and clinical risk of bleeding in patients with severe haemophilia A or B.

Bleeding severity in severe haemophilic patients, with low thrombin generation (TG) capacity, can vary widely between patients, possibly reflecting differences in tissue factor pathway inhibitor (TFPI) level. To compare free TFPI (fTFPI) levels in patients with severe haemophilia A (sHA) and severe haemophilia B (sHB) and to investigate in these patients as a whole the relationships between bleeding and TG potential, between TG potential and fTFPI level and between fTFPI level and bleeding tendency. Data on bleeding episodes retrospectively recorded during follow-up visits over 5-10 years were collected and used to calculate the annualised joint bleeding rate (AJBR). fTFPI levels and basal TG parameters were determined in platelet-poor plasma (PPP) and platelet-rich plasma (PRP) using calibrated automated tomography (CAT). Mean fTFPI levels did not differ significantly between sHA (n=34) and sHB (n=19) patients. Mean values of endogenous thrombin potential (ETP) and thrombin peak (peak) in PPP and PRP were two-fold higher when fTFPI levels<9.4 versus>14.3ng/mL. In patients treated on demand, ETP and peak in PRP were doubled when AJBR was , AJBR being halved in patients with a low fTFPI level (9.4ng/mL). In patients on factor prophylaxis, no association was found between TG parameters and either fTFPI level or AJBR. In patients treated on demand, bleeding tendency was influenced by fTFPI levels, which in turn affected basal TG potential. In patients on prophylaxis, bleeding tendency is probably determined primarily by the intensity of this treatment.

SARS-CoV-2 vaccines are not associated with hypercoagulability in apparently healthy people

BackgroundSARS-CoV-2 adenoviral vector DNA vaccines have been linked to the rare but serious thrombotic postvaccine complication vaccine-induced immune thrombotic thrombocytopenia. This has raised concerns regarding the possibility of increased thrombotic risk after any SARS-CoV-2 vaccines. ObjectivesTo investigate whether SARS-CoV-2 vaccines cause coagulation activation leading to a hypercoagulable state. MethodsThis observational study included 567 health care personnel; 521 were recruited after the first dose of adenoviral vector ChAdOx1-S (Vaxzevria, AstraZeneca) vaccine and 46 were recruited prospectively before vaccination with a messenger RNA (mRNA) vaccine, either Spikevax (Moderna, n = 38) or Comirnaty (Pfizer-BioNTech, n = 8). In the mRNA group, samples were acquired before and 1 to 2 weeks after vaccination. In addition to the prevaccination samples, 56 unvaccinated blood donors were recruited as controls (total n = 102). Thrombin generation, D-dimer levels, and free tissue factor pathway inhibitor (TFPI) levels were analyzed. ResultsNo participant experienced thrombosis, vaccine-induced immune thrombotic thrombocytopenia, or thrombocytopenia (platelet count <100 × 109/L) 1 week to 1 month postvaccination. There was no increase in thrombin generation, D-dimer level, or TFPI level in the ChAdOx1-S vaccine group compared with controls or after the mRNA vaccines compared with baseline values. Eleven of 513 (2.1%) participants vaccinated with ChAdOx1-S had anti-PF4/polyanion antibodies without a concomitant increase in thrombin generation. ConclusionIn this study, SARS-CoV-2 vaccines were not associated with thrombosis, thrombocytopenia, increased thrombin generation, D-dimer levels, or TFPI levels compared with baseline or unvaccinated controls. These findings argue against the subclinical activation of coagulation post-COVID-19 vaccination.

Activated factor XI is associated with increased factor VIIa - Antithrombin complexes in stable coronary artery disease: Impact on cardiovascular outcomes.

Coronary artery disease (CAD) is associated with a prothrombotic tendency including increased factor (F) VIIa-antithrombin (FVIIa-AT) complexes, a measure of tissue factor (TF) exposure, and activated FXI (FXIa). We investigated whether increased FVIIa-AT complexes are associated with FXIa and active TF and if major adverse clinical outcomes are predicted by the complexes in CAD. In 120 CAD patients, we assessed FVIIa-AT complex concentrations and the presence of circulating FXIa and active TF. Levels of 8-iso-prostaglandin F2α (8-iso-PGF2α), interleukin-6, high-sensitivity C reactive protein, prothrombin fragment 1 + 2, and free Tissue Factor Pathway Inhibitor were determined. Myocardial infarction (MI), ischemic stroke, systemic thromboembolism (SE), and cardiovascular (CV) death were recorded separately and as a composite endpoint, during follow-up. FVIIa-AT complexes were positively associated with current smoking and multivessel CAD. Elevated FVIIa-AT complexes characterized patients with circulating FXIa and/or active TF in association with increased plasma isoprostanes but not with thrombin generation or inflammatory markers. During a median follow-up of 106 months (interquartile range 95-119), high baseline levels of FVIIa-AT complexes predicted ischemic stroke/SE (HR 4.61 [95% CI 1.48-18.42]) and a composite endpoint of MI, stroke/SE, and CV death (HR 7.47 [95% CI 2.81-19.87]). This study is the first to show that high FVIIa-AT complexes characterize advanced CAD patients with detectable FXIa and active TF, which is, in part, driven by oxidative stress. High FVIIa-AT complexes were associated with the risk of ischemic stroke/SE during long-term follow-up, highlighting the need for effective antithrombotic agents in CAD.

Persisting Endothelial Cell Activation and Hypercoagulability after COVID-19 Recovery—The Prospective Observational ROADMAP-Post COVID-19 Study

Background. Hypercoagulable state and endothelial cell activation are common alterations in patients with COVID-19. Nevertheless, the hypothesis of persistent hypercoagulability and endothelial cell activation following recovery from COVID-19 remains an unresolved issue. Objectives. To investigate the persistence of endothelial cell activation and hypercoagulability after recovery from COVID-19. Patients/Methods. COVID-19 survivors (n = 208) and 30 healthy individuals were enrolled in this study. The following biomarkers were measured: procoagulant phospholipid-dependent clotting time (PPL-ct), D-Dimer, fibrin monomers (FM), free Tissue factor pathway inhibitor (free-TFP)I, heparinase, and soluble thrombomodulin (sTM). Antibodies against SARS-CoV-2 (IgG and IgA) were also measured. Results. The median interval between symptom onset and screening for SARS-CoV-2 antibodies was 62 days (IQR = 22 days). Survivors showed significantly higher levels of D-Dimers, FM, TFPI, and heparanase as compared to that of the control group. Survivors had significantly shorter PPL-ct. Elevated D-dimer was associated with older age. Elevated FM was associated with female gender. Elevated heparanase was independently associated with male gender. Decreased Procoag-PPL clotting time was associated with female gender. One out of four of COVID-19 survivors showed increase at least one biomarker of endothelial cell activation or hypercoagulability. Conclusions. Two months after onset of COVID-19, a significant activation of endothelial cells and in vivo thrombin generation persists in at least one out of four survivors of COVID-19. The clinical relevance of these biomarkers in the diagnosis and follow-up of patients with long COVID-19 merits to be evaluated in a prospective clinical study.

Target‐mediated drug disposition modeling of an anti‐TFPI antibody (MG1113) in cynomolgus monkeys to predict human pharmacokinetics and pharmacodynamics

BackgroundMG1113 is a human monoclonal antibody of tissue factor pathway inhibitor (TFPI) under development for prophylaxis for hemophilia patients with or without inhibitors against factor VIII products, which have been used for the treatment of hemophilia. Because TFPI is a negative regulator in the extrinsic coagulation pathway, neutralization of TFPI function by MG1113 can potentially increase coagulation activity by bypassing the intrinsic coagulation pathway, which factor VIII activates. ObjectivesThis study aims to determine the correlation between pharmacokinetics (PK) and pharmacodynamics (PD) after administering MG1113 to monkeys and to predict the PK and PD of MG1113 in humans by the Target‐Mediated Drug Disposition (TMDD) model using the results from monkeys. MethodsThe PK profile of MG1113 and the PD effect on the free TFPI level were evaluated after intravenous (IV) and subcutaneous (SC) administrations of MG1113 (2.5, 5, and 10 mg/kg) to male cynomolgus monkeys. After setting up the PK/PD model on monkeys, PK parameters on humans were calculated using allometric scaling, and then clinically effective doses were predicted applying the TMDD model. Results and ConclusionsMG1113 showed nonlinear PK after both IV and SC administrations at the dosing range from 2.5 to10 mg/kg. The concentrations of MG1113 versus TFPI could be characterized a dose‐response relationship using a TMDD model. The TMDD modeling and simulation built in this study were used to simulate various dosage regimens of MG1113 to apply to the first‐in‐human study design, and moreover expected to be referred to establish the dose for further clinical trials.

A rare coding mutation in the MAST2 gene causes venous thrombosis in a French family with unexplained thrombophilia: The Breizh MAST2 Arg89Gln variant.

Rare variants outside the classical coagulation cascade might cause inherited thrombosis. We aimed to identify the variant(s) causing venous thromboembolism (VTE) in a family with multiple relatives affected with unprovoked VTE and no thrombophilia defects. We identified by whole exome sequencing an extremely rare Arg to Gln variant (Arg89Gln) in the Microtubule Associated Serine/Threonine Kinase 2 (MAST2) gene that segregates with VTE in the family. Free-tissue factor pathway inhibitor (f-TFPI) plasma levels were significantly decreased in affected family members compared to healthy relatives. Conversely, plasminogen activator inhibitor-1 (PAI-1) levels were significantly higher in affected members than in healthy relatives. RNA sequencing analysis of RNA interference experimental data conducted in endothelial cells revealed that, of the 13,387 detected expressed genes, 2,354 have their level of expression modified by MAST2 knockdown, including SERPINE1 coding for PAI-1 and TFPI. In HEK293 cells overexpressing the MAST2 Gln89 variant, TFPI and SERPINE1 promoter activities were respectively lower and higher than in cells overexpressing the MAST2 wild type. This study identifies a novel thrombophilia-causing Arg89Gln variant in the MAST2 gene that is here proposed as a new molecular player in the etiology of VTE by interfering with hemostatic balance of endothelial cells.

MG1113, a specific anti–tissue factor pathway inhibitor antibody, rebalances the coagulation system and promotes hemostasis in hemophilia

BackgroundReplacement therapy is the most common treatment for reduction of bleeding and control of episodic bleeding in individuals with hemophilia. Despite the proven effectiveness of factor replacement therapy, repeated intravenous administration is a heavy burden to individuals with hemophilia. ObjectivesTo reduce the burden, therapeutic agents that can be subcutaneously administered need to be developed, and an anti–tissue factor pathway inhibitor (TFPI) antibody may be a suitable candidate for this purpose. MethodsMG1113 is an IgG4 monoclonal antibody that binds to Kunitz‐2 domain (KD2) of TFPI. To confirm the coagulation potential of MG1113, several tests were conducted using factor VIII (FVIII)‐ or IX (FIX)‐deficient plasma. For the ex vivo spiking test, platelet‐poor plasma samples from 14 individuals with hemophilia were spiked with MG1113. The in vivo efficacy was determined using blood loss tests, modified prothrombin time (mPT), and free TFPI quantification after intravenous or subcutaneous administration of MG1113 into hemophilia A (HA)‐induced rabbits. ResultsRadiographic crystallography demonstrated the specific binding site between MG1113 and KD2. In FVIII‐deficient plasma and the plasma of individuals with hemophilia, peak thrombin and endogenous thrombin levels were increased by MG1113 in a concentration‐dependent manner. Rotational thromboelastometry assay revealed that clotting time, clot formation time, and maximum clot firmness were normalized in MG1113‐treated blood of patients. Intravenous or subcutaneous injection of MG1113 into HA‐induced rabbits resulted in rebalancing of blood loss, mPT, and free TFPI levels. ConclusionsThese results indicate that subcutaneous administration of MG1113 neutralizes the function of TFPI and regulates bleeding in individuals with hemophilia.

Subcutaneous concizumab prophylaxis in hemophilia A and hemophilia A/B with inhibitors: phase 2 trial results

AbstractResults from the main parts (24 weeks) of 2 concizumab phase 2 trials are presented: explorer4 in hemophilia A (HA) or B (HB) with inhibitors (HAwI/HBwI) and explorer5 in HA. The trials aimed to evaluate the efficacy of daily subcutaneous concizumab prophylaxis (evaluated as annualized bleeding rate [ABR] at last dose level), with secondary objectives being safety and immunogenicity (assessed as number of adverse events [AEs] and antidrug antibodies [ADAs]). Patients received 0.15 mg/kg concizumab, with potential dose escalation to 0.20 and 0.25 mg/kg (if ≥3 spontaneous bleeding episodes within 12 weeks of concizumab treatment). Relevant pharmacokinetic/pharmacodynamic (PK/PD) parameters were assessed. Thirty-six HA, 9 HAwI, and 8 HBwI patients were exposed to concizumab. Most inhibitor patients (15 of 17; 88.2%) did not escalate the dose; all patients chose to continue to the extension phase of the trials. Clinical proof of concept for prevention of bleeding episodes was demonstrated in both trials. Estimated ABRs in HAwI and HBwI were lower vs HA: 3.0 (95% confidence interval [CI], 1.7; 5.3) and 5.9 (95% CI, 4.2; 8.5) vs 7.0 (95% CI, 4.6; 10.7), respectively. PK/PD results were as expected, with no difference between hemophilia subtypes for concizumab exposure, free tissue factor pathway inhibitor, thrombin generation, prothrombin fragment 1+2, and d-dimers. Concizumab was safe and well tolerated (no severe AEs, AE-related withdrawals, or thromboembolic events). Three patients had (very low to medium titer) ADA+ tests in each trial, with no observed clinical effect. These results support further development of concizumab as a daily prophylactic treatment in all hemophilia patients. These trials were registered at www.clinicaltrials.gov as #NCT03196284 and #NCT03196297.

Low factor V level ameliorates bleeding diathesis in patients with combined deficiency of factor V and factor VIII

AbstractCombined factor V (FV) and FVIII deficiency (F5F8D) is a rare autosomal-recessive bleeding disorder caused by mutations in lectin mannose binding-1 (LMAN1) and multiple coagulation factor deficiency-2 (MCFD2). Six causative homozygous mutations (5 in LMAN1 and 1 in MCFD2) were identified in 6 patients with F5F8D. A thrombin-generation assay, triggered with tissue factor (1 pM) in F5F8D plasma, paradoxically exhibited enhanced thrombin generation compared with normal plasma. Significantly lower free tissue factor pathway inhibitor (fTFPI) was found in F5F8D patients compared with healthy controls (P < .01). Normalizing tissue factor pathway inhibitor α (TFPIα) in F5F8D plasma greatly delayed and reduced thrombin generation. Increasing FV concentrations by adding plasma FV to F5F8D plasma only caused a gradual decrease in thrombin generation, suggesting that low levels of TFPIα and FV cocontributed to the elevated thrombin generation by reducing anticoagulant effects. On the contrary, thrombin generation in F5F8D platelet-rich plasma (PRP) was significantly lower than in normal controls (P < .05); however, it was fully corrected by normalizing FVIII or after 1-deamino-8-d-arginine vasopressin (DDAVP) infusion, indicating that the hypocoagulable state of F5F8D patients is associated with low FVIII levels. In addition, plasma and platelet FV in F5F8D PRP were sufficient to support normal thrombin generation, and low TFPIα may have no effect on thrombin generation. DDAVP infusion induced a complete response in 5 F5F8D patients and a partial response in the remaining patient. Based on our findings, we suggest that DDAVP may be considered a potential substitute for FVIII concentrates, and fresh-frozen plasma (FFP) infusion may not be necessary for F5F8D patients with minor bleeding challenges.

Coagulation System Disorders and Thrombosis Prophylaxis During Laparoscopic Fundoplications.

The aim of this study was to assess and recommend the optimal deep vein thrombosis (DVT) prophylaxis regimen during and after laparoscopic fundoplication according to the blood coagulation disorders and the rate of DVT in 2 patient groups, receiving different DVT prophylaxis regimens. This was a prospective randomized, single-center clinical study. The study population, 121 patients, were divided into 2 groups: group I received low-molecular-weight heparin 12 hours before the operation; group II received low-molecular-weight heparin only 1 hour before the laparoscopic fundoplication. Both groups received intermittent pneumatic compression during the entire procedure. Bilateral Doppler ultrasound to exclude DVT was performed before the surgery. Venous phase computed tomographic images were acquired from the ankle to the iliac tubercles on the third postoperative day to determine the presence and location of DVT. Hypercoagulation state was assessed by measuring the prothrombin fragment F1+2 (F1+2), the thrombin-antithrombin complex (TAT), and tissue factor microparticles activity (MP-TF) in plasma. The hypocoagulation effect was evaluated by measuring plasma free tissue factor pathway inhibitor (fTFPI). F1+2, TAT, and MP-TF indexes increased significantly, whereas fTFPI levels decreased significantly during and after laparoscopic fundoplication, when molecular-weight heparin was administered 12 hours before the operation. Computed tomography venography revealed peroneal vein thrombosis in 2 group I patients on the third postoperative day. Total postsurgical DVT frequency was 1.65%: 3.6% in group I, with no DVT in group II. Molecular-weight heparin and intraoperative intermittent pneumatic compression controls the hypercoagulation effect more efficiently when it is administered 1 hour before surgery: it causes significant reduction of F1+2, TAT, and MP-TF indexes and significant increases of fTFPI levels during and after laparoscopic fundoplication.

Levels of tissue factor pathway inhibitor in patients with inflammatory bowel disease.

INTRODUCTION Endothelial dysfunction has been reported to be involved in the pathogenesis of inflammatory bowel disease (IBD) and concomitant thromboembolic complications. Inflammation stimulates the expression of tissue factor and tissue factor pathway inhibitor (TFPI) by endothelial cells. OBJECTIVES This study assessed the relationship between TFPI levels and disease activity in patients with IBD. PATIENTS AND METHODS A total of 50 consecutive adult patients with ulcerative colitis (UC), 50 patients with Crohn disease (CD), and 50 healthy controls were enrolled to the study. Plasma levels of total TFPI, free TFPI, and von Willebrand factor were measured. Associations among these levels, disease activity, and inflammatory marker levels were assessed. RESULTS Total TFPI levels were higher in patients with IBD (median, 68.5 [IQR, 60.2-80.1] ng/ml) than in controls (median, 61.1 ng/ml [IQR, 54.3-74.2]; P = 0.01). Free TFPI levels were higher in patients with active UC (median, 12.8 ng/ml [IQR, 11.1-15.4]), inactive UC (median, 9.9 ng/ml [IQR, 7.3-11.5]), active CD (median, 11.7 [IQR, 9.7-14.4] ng/ml), and inactive CD (median, 9.7 ng/ml [IQR, 8.6-11.6]) than in controls (median, 5.5 ng/ml [IQR, 4.3-7.2]; P <0.001). In the CD and UC groups, free TFPI levels correlated with the levels of inflammatory markers and disease activity. The von Willebrand factor level was higher in patients with UC (median, 143.4 IU/dl [IQR, 115.5-170.4]) and those with CD (median, 151.8 IU/dl [IQR, 112.8-189.4]) than in controls (85.1 IU/dl [IQR, 77.1-101.5]; P <0.001 for both comparisons). CONCLUSIONS The anticoagulant TFPI pathway is activated during remissions and flares in patients with IBD. The free TFPI level correlates with biochemical markers of inflammation and disease activity.

Pharmacodynamics, Pharmacokinetics and Safety of Bay 1093884, an Antibody Directed Against Human TFPI, in Patients with Factor VIII or IX Deficiency (With and Without Inhibitors): A Phase 1 Study

Background: BAY 1093884 is a fully human monoclonal antibody directed against the K1 and K2 domains of human tissue factor pathway inhibitor (TFPI). TFPI regulates the initiation of coagulation and is important for regulation of normal hemostatic response. In factor (F)VIII and FIX deficiency (hemophilia A [HA] and B [HB], respectively), lack of adequate amplification (FXa generation) in tandem with intact regulation contributes to reduced clotting. Inhibition of TFPI has the potential to normalize coagulation in hemophilia even in the absence of FVIII or FIX and it is expected to result in normalization of thrombin generation and consequently improvement in clot formation. TFPI is an attractive therapeutic target as it is unaffected by FVIII or FIX inhibitors and can be targeted in both HA and HB. A potential advantage of targeting TFPI is that downstream mechanisms that protect from excessive coagulation (including antithrombin), remain intact.Methods: BAY 1093884 was evaluated in a multicenter, open-label study in patients with severe HA or HB, with or without inhibitors. Safety, pharmacokinetics (PK) and pharmacodynamics (PD) were assessed after single intravenous (IV) (0.3 and 1 mg/kg) and subcutaneous (SC) (1, 3, and 6 mg/kg) doses. A multiple-dose (MD) cohort received BAY 1093884 150 mg SC once weekly for 6 weeks. Total and free TFPI protein levels and TFPI activity were measured. Thrombin generation assay (TGA) parameters were measured using a calibrated automated thrombogram. Clot formation was assessed using rotational thromboelastometry (ROTEM). A mechanistic physiology-based PK/PD (PBPK/PD) model was developed based on single-dose PK data observed in the study, and used to determine dosing in the MD cohort. Data for HA, HB, Japanese and inhibitor patient subgroups were analyzed separately.Results: Thirty-two patients were enrolled; 30 with HA and 2 with HB, of which 4 (3 HA, 1 HB) were included in the MD cohort. At least 4 patients were treated in each administration method/dose group. Clot formation using ROTEM was assessed in 6 patients. Total and free TFPI-related parameters showed dose-dependent effects, with the concentrations being below the lower limit of quantification for longer duration at higher doses. Improvements in TGA parameters were observed following both IV and SC administration; duration of improvement was longer at higher doses. BAY 1093884 led to shortening of the clotting time in all 6 patients tested. Dose-dependent increases in plasma concentration exceeding dose proportionality were seen following IV and SC administration, consistent with expectations of target-mediated drug disposition for BAY 1093884. Moderate accumulation was observed after MD. Limited information on subgroups (patients with inhibitors [n=4], patients with HB [n=2] and Japanese origin [n=1]) suggests that the PK and PD data for these subgroups were consistent with those from non-inhibitor HA patients. The PBPK/PD model adequately described the concentration time course and total TFPI following single-dose IV and SC administration of BAY 1093884; the PK and PD data from the MD cohort were as predicted by the model. The model also supported that the PK/PD of BAY 1093884 are independent of inhibitor status. No serious adverse events, deaths, or adverse events leading to discontinuation were observed. Fibrinogen and platelet counts remained within normal range at most visits and no meaningful changes in levels of antithrombin, protein C, or FV were seen. The mechanisms for anticoagulation and fibrinolysis were intact.Conclusions: Overall, BAY 1093884 gave no safety concerns in the dose range evaluated. Results suggest that BAY 1093884 shifts hemostatic balance towards greater thrombin generation and clot formation as intended. PK/PD characteristics were similar for inhibitor and HB patients as compared with HA patients, potentially supporting use in all of these patient types. The PBPK/PD model developed can be used for dose selection in future studies. Treatment efficacy will be evaluated in a future study. DisclosuresChowdary:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Swedish Orphan Biovitrum AB (Sobi): Honoraria; Baxalta (Shire): Honoraria, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Freeline: Consultancy; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biogen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria. Lissitchkov:Novo Nordisk: Other: Investigator fees as a participant of the clinical trial. Willmann:Bayer: Employment. Schwers:Bayer: Employment. Michaels:Bayer: Employment. Shah:Bayer: Employment.

Lipid-Mediated Relation between Tissue Factor Pathway Inhibitor Activity and Cardiovascular Risk Factors and Diseases in a Large Population Sample

▪Background: Tissue factor pathway inhibitor (TFPI), a Kunitz-type serine protease, is a potent anticoagulant protein in the extrinsic coagulation pathway and acts by inhibiting both the FXa and the Tissue Factor-FVIIa complex. In contrast to total and free TFPI antigen levels, the reference values and clinical determinants of total TFPI activity have not yet been studied in detail in the general population. In the present study, we aim to identify the cardiovascular determinants for total TFPI activity and investigate its association with cardiovascular disease (CVD) and total mortality, in a population at large.Methods: For this study, the first 4779 subjects of the population-based Gutenberg Health Study were examined in a highly standardized setting. Total TFPI activity was assessed in platelet poor plasma by the Actichrome TFPI activity assay (American Diagnostica, Stamford, CT, USA). Sex-specific nomograms were developed to demonstrate the relation of total TFPI activity with age. Multivariable regression analysis was performed to assess the determinants of total TFPI activity and to evaluate the association with CVD. Cox-regression models, adjusted for age, sex, cardiovascular risk factors (CVRFs) and CVD, were calculated to investigate the association between total TFPI activity and total mortality.Results: The multivariable linear regression analysis identified smoking (β, 0.0952 [0.0541 to 0.136],) as a positive determinant for total TFPI activity, while diabetes (β, -0.0716 [-0.134 to -0.00905],), obesity (β, -0.0627 [-0.101 to -0.024],) and history of coronary artery disease (CAD) were negatively associated with TFPI activity, independent of age, sex and the remaining CVRFs. After adjustment for high-density lipoprotein levels (HDL), low-density lipoproteins (LDL) and triglycerides, the association between TFPI activity levels and obesity and CAD was lost. The analysis additionally reveals a strong positive association between TFPI activity levels and LDL (β, 0.221 [0.204 to 0.237],). The Cox regression models revealed that a higher TFPI activity, above 97.5th percentile of the reference group, was associated with an increased mortality risk (HR = 2.58, [95% CI: 1.49/4.47], p=0.00074) independent of age, sex, CVRFs, CVD, oral contraceptives and hormonal replacement therapy. After additional adjustment for LDL levels, this relation became stronger.Conclusion: To the best of our knowledge, this is the first large, epidemiological study of the general population, revealing an increased mortality risk in individuals with higher TFPI activity, independent of CVRFs and CVD and emphasized by LDL-levels. Additionally, it demonstrates the negative association between total TFPI activity levels and CVD, particularly CAD. Furthermore, an association between TFPI activity and obesity, mediated through lipoprotein particles is explored. Lastly, it describes the age- and sex-related reference range of total TFPI activity levels in a large population-based data set. DisclosuresNo relevant conflicts of interest to declare.

Biomarkers for the risk of thrombosis in pancreatic adenocarcinoma are related to cancer process.

BackgroundVenous thrombo-embolic events (VTE) frequently occur in patients with pancreatic ductal adenocarcinoma (PDAC) and contribute to high morbidity and mortality.ObjectivesTo determine whether VTE biomarkers are related to cancer, inflammation or precancerous states and to assess their relevance to predict VTE in PDAC.Patients and MethodsWe compared VTE biomarkers in patients with PDAC (n = 42), intraductal papillary mucinous neoplasm of the pancreas (IPMN, n = 48) or chronic pancreatitis (n = 50). PDAC patients were followed-up for 6 months.ResultsFactor VIII, D-dimers, von Willebrand factor, free tissue factor pathway inhibitor and microvesicle-tissue factor (MV-TF) activity were higher in PDAC patients compared to patients with IPMN or chronic pancreatitis. PDAC patients with metastasis presented higher D-dimers and MV-TF activity compared to patients with localized lesions, but elevation of D-dimers was dependent on tumor size. In multivariate analysis, elevated D-dimers (≥2.16 µg/mL) or MV-TF activity (≥2.37 pg/mL) were significant risk factors for VTE in PDAC patients, after adjustment for age and sex (HR 4.9 [1.0–23.1] or HR 10.5 [1.5–72.4], mean [interquartile range], respectively). Cumulative probability of VTE at 6 months was higher in patients with elevated D-dimers (56.3% vs 15.6%, p = 0.009) and in patients with high MV-TF activity (74.3% vs 21.7%, p = 0.01).ConclusionsVTE biomarkers including D-dimers and MV-TF activity are not related to inflammation but rather to cancer process and dissemination. D-dimers and MV-TF activity are associated to future VTE in PDAC patients and could help identify patients who could benefit from thromboprophylaxis.

Mechanistic Modeling of the Pharmacodynamic and Pharmacokinetic Relationship of Tissue Factor Pathway Inhibitor-Neutralizing Antibody (BAY 1093884) in Cynomolgus Monkeys

BAY 1093884 is a fully human monoclonal antibody against the tissue factor pathway inhibitor (TFPI) in development as prophylaxis in patients with hemophilia with or without inhibitors. In vitro, BAY 1093884 binds to human, mouse, and monkey TFPI. The objective of this study was to find a pharmacodynamic (PD) biomarker after administration of BAY 1093884 to normal monkeys. In monkey plasma, BAY 1093884 exhibited an IC50 (concentration that inhibits 50%) of 4.65 and 6.19 nM for free TFPI and diluted prothrombin time (dPT), respectively. The BAY 1093884 pharmacokinetic (PK) profile and its PD effects on dPT and free TFPI levels were assessed after intravenous and subcutaneous administration of BAY 1093884 (5 and 20 mg/kg) to female cynomolgus monkeys. Free TFPI concentrations in plasma decreased rapidly and increased to baseline in a dose-dependent manner. dPT clotting time was shortened and correlated with free TFPI levels and drug concentration in plasma, demonstrating the relationship between PD activities (dPT clotting time and free TFPI levels) and drug concentration. BAY 1093884 exhibited nonlinear PK, and a target-mediated drug disposition model was used to characterize the BAY 1093884 versus TFPI concentration–response relationship. We concluded that a mechanism-based PK/PD binding model could be useful for predicting human response to BAY 1093884. For the first-in-human study, measurement of free TFPI will be included as part of the dose-escalation design.

The cross-sectional association between vasomotor symptoms and hemostatic parameter levels in postmenopausal women.

Vasomotor symptoms (VMS) may be a marker of cardiovascular risk. We aimed to evaluate the cross-sectional association of VMS presence and severity with hemostatic parameter levels measured at baseline among Women's Health Initiative (WHI) Hormone Therapy trial postmenopausal participants. This cross-sectional analysis included 2,148 postmenopausal women with measures of VMS presence and severity reported in the 4 weeks before WHI baseline, who were not using warfarin or hormone therapy and for whom the following baseline hemostatic parameters were measured within the WHI Cardiovascular Disease Biomarker Case-Control Study: antithrombin, plasminogen activator inhibitor-1, protein C antigen, total and free protein S antigen, total and free tissue factor pathway inhibitor, D-dimer, normalized activated protein C sensitivity ratio, and thrombin generation. Using multiple linear regression, we estimated the adjusted average difference in each hemostatic parameter associated with VMS presence and severity. A multiple comparisons-corrected P value was computed using the P-min procedure to determine statistical significance of our smallest observed P value. Women were 67 years of age on average and 33% reported VMS presence at baseline. There was some suggestion that VMS presence may be associated with a -0.34 adjusted difference in normalized activated protein C sensitivity ratio compared with no VMS (95% CI, -0.60 to -0.087; P = 0.009), but this association was not significant after correction for multiple comparisons (P = 0.073). VMS presence or severity was not significantly associated with the other hemostatic parameters. We found no convincing evidence that VMS presence or severity was associated with levels of hemostatic parameters among postmenopausal women.

Procoagulant activity in patients with combined type 2 diabetes and coronary artery disease: No effects of long-term exercise training.

We investigated the effects of 12-month exercise training on hypercoagulability in patients with combined type 2 diabetes mellitus and coronary artery disease. Associations with severity of disease were further explored. Patients ( n = 131) were randomized to exercise training or a control group. Blood was collected at inclusion and after 12 months. Tissue factor, free and total tissue factor pathway inhibitor, prothrombin fragment 1 + 2 (F1 + 2) and D-dimer were determined by enzyme-linked immunosorbent assay and ex vivo thrombin generation by the calibrated automated thrombogram assay. Tissue factor and ex vivo thrombin generation increased from baseline to 12 months ( p < 0.01, all), with no significant differences in changes between groups. At baseline, free and total tissue factor pathway inhibitor significantly correlated to fasting glucose ( p < 0.01, both) and HbA1c ( p < 0.05, both). In patients with albuminuria ( n = 34), these correlations were strengthened, and elevated levels of D-dimer, free and total tissue factor pathway inhibitor ( p < 0.01, all) and decreased ex vivo thrombin generation ( p < 0.05, all) were observed. These results show no effects of exercise training on markers of hypercoagulability in our population with combined type 2 diabetes mellitus and coronary artery disease. The association between poor glycaemic control and tissue factor pathway inhibitor might indicate increased endothelial activation. More pronounced hypercoagulability and increased tissue factor pathway inhibitor were demonstrated in patients with albuminuria.

The Levels of Tissue Factor Pathway Inhibitor in Sepsis Patients Receiving Prophylactic Enoxaparin.

Objective:Sepsis syndrome is usually accompanied by activation of blood coagulation mechanisms. Earlier studies found deficiencies of the 3 main natural anticoagulants, antithrombin, protein C, and protein S. However, none of these inhibitors block tissue factor, the prime trigger of coagulation during sepsis that is controlled specifically by the tissue factor pathway inhibitor (TFPI). The aim of this study was to characterize the fluctuations in the levels of natural anticoagulants, particularly TFPI, in the course of sepsis and to find out their association with the anticoagulant action of the low-molecular-weight heparin enoxaparin.Materials and Methods:We studied 51 consecutive patients with sepsis. Blood samples were collected from patients at baseline (0 h) and at 4, 12, and 24 h after enoxaparin administration. The following assays were undertaken using commercial kits: activated partial thromboplastin time, prothrombin time, thrombin time, total and free TFPI, protein C and protein S, antithrombin, fibrinogen, and anti-factor Xa.Results:Before enoxaparin administration, there was significant prolongation of the prothrombin time and activated partial thromboplastin time, and this remained the case in the 3 subsequent samples. There was marked reduction in the levels of antithrombin, protein C, and total and free protein S to below control values throughout the study. In contrast, plasma levels of both total and free TFPI were markedly elevated and increased after enoxaparin therapy. Anti-factor Xa levels were within the therapeutic range throughout. There was no difference in TFPI levels between those patients who died and those who survived.Conclusion:Sepsis triggered marked release of TFPI from endothelial cells. This persisted and was increased further following the administration of enoxaparin. In contrast, there was marked consumption of the natural coagulation inhibitors antithrombin, protein C, and protein S. These results go some way towards explaining why the therapeutic use of recombinant TFPI fails to correct sepsis-associated coagulopathy.

PO-24 - Determinants of thrombin generation in gynaecological malignancies

Increased thrombin production is associated with malignancy and is a marker for venous thromboembolism (VTE). Our group has shown that thrombin generation is increased in gynaecological malignancies. Although tumour derived Tissue Factor (TF) has been implicated, the precise mechanism by which thrombin production is increased is not fully understood. Our group has shown that gynaecological cancers can alter tumour expression of cogulation proteases. These changes may be implicated in the increased thrombin generation observed. Previous studies in normal control patients by other groups have shown that multiple coagulation factors are implicated in thrombin generation and that the effects depend on assay conditions however free Tissue Factor Pathway Inhibitor (TFPI), Factors V, VIIIc and protein S, were significant determinants of thrombin generation. The aim of this study was to determine the effect of factor V factor, VIIIc, TFPI and free protein S on the thrombin generation in patients with endometrial and ovarian cancer compared with benign controls. Patients with a gynaecological malignancy (n=43) (ovarian or endometrial) were matched with patients with a benign tumour (n=43) gave full and informed consent. Venous blood samples were obtained prior to surgery and chemotherapy. Thrombin generation was was measured using a fluorogenic assay. Lag time, peak thrombin and area under the thrombin generation curve (ETP) was determined and reported for each sample. Free protein S, free TFPI and factor V were determined using ELISA. Factor VIIIc was determined using a hromogenic assay. Factor V and factor VIIIc were significantly increased in the malignant group compared with the benign group (P<0.03; P<0.006). Increased free TFPI levels were also observed in the malignant group but this did not reach significance (P<0.06). There was no difference in free Protein S levels between the groups. Highest levels of peak thrombin generation were observed in the high grade serous and clear cell ovarian cancer patients. Changes were less marked in the endometrial patients. Free TFPI, factor V and factor VIIIc were important determinants of thrombin generation in the malignant group. Coagulation factors V and VIIIc and free TFPI are altered in patients with gynaecological malignancies and contribute to the increased thrombin generation found in these cancer patients. We have previously found increased expression of factor V in tumours from patients with ovarian cancer in addition to increased TF expression. These changes may explain the high rate of venous thromboembolism found in these patients.

OC-06 - Pro-thrombotic biomarkers in pancreatic diseases: are they specific of cancer?

Venous thrombo-embolic events (VTE) occur frequently in patients with pancreatic cancer and contribute to elevated morbidity and mortality. Clinical risk factors for thrombosis such as cancer stage and tumor grade have been clearly identified. Recently, several biomarkers have been proposed which may help identifying cancer patients at high risk of thrombosis. Those biomarkers have been studied in heterogeneous cohorts of patients with different cancer types. To compare pro-thrombotic biomarkers in pancreatic cancer and in chronic pancreatitis to determine whether these biomarkers are related to cancer or inflammation and to validate their association with thrombotic risk in a pancreatic cancer population. 45 patients with pancreatic cancer, 49 with intraductal papillary mucinous tumor of the pancreas (IPMN), a precancerous lesion, and 50 with chronic pancreatitis were recruited. Plasma levels of factor VIII, D-dimers, thrombin-antithrombin complexes, soluble p-selectin, tissue factor-dependent procoagulant activity of MP (TF-MP), free Tissue Factor Pathway Inhibitor (TFPI) and extracellular DNA were measured. Thrombin generation triggered by 1pM of TF was evaluated with the Calibrated Automated Thrombogram assay. Levels of factor VIII, D-dimers, TF-MP, TFPI and extracellular DNA were significantly higher in cancer patients compared to IPMN or chronic pancreatitis (Table1). Patients with metastatic cancer (n=27) presented higher levels of D-dimers (mean±sd 1.77±1.28 vs 0.80±0.96 μg/ml, p=0.004) and MP-TF (54.3±53.2 vs 15.8±10.4 fM, p=0.02) compared to patients with localized lesions (n=18). Among cancer patients, 42 were followed for a median duration of 187 days (min 21-max 802 days). VTE occurred in 10 (23%) patients. All had metastatic cancer at the time of thrombosis. Only D-dimers were significantly elevated in cancer patients with VTE compared to patients without VTE (median 1.85 vs 0.7 μg/ml, p=0.02). Elevation of factor VIII, D-dimers, TF-MP, TFPI and extracellular DNA seems to be related to cancer process, not to local or systemic inflammation as these parameters differentiate cancer from chronic pancreatitis. Interestingly, D-dimers and TF-MP are related to the disseminated cancer stage, suggesting that vascular invasion is a prerequisite to the release of TF-MP from the primary tumor into the bloodstream and to coagulation activation. However, only D-dimers are associated with the occurrence of future VTE. We propose that D-dimers could be a useful tool to predict thrombotic events in pancreatic cancer patients. This should be confirmed in a larger population.