Thrombotic and Hemorrhagic Issues Associated with Myeloproliferative Neoplasms.

Thrombotic and hemorrhagic complications are related to a significant rate of morbidity and mortality in patients with myeloproliferative neoplasms (MPNs), they are therefore called "thrombohemorrhagic" syndromes. Several clinical factors, such as age and presence of cardiovascular comorbidities are responsible for thrombotic complications. High blood counts, platelet alterations, presence of JAK2 mutation and possibly of other CHIP mutations such as TET2, DNMT3A, and ASXL1, procoagulant microparticles, NETs formation, endothelial activation and neo-angiogenesis are some of the parameters accounting for hypercoagulability in patients with myeloproliferative neoplasms. Bleeding complications emerge as a result of platelet exhaustion. They can be also linked to a functional deficiency of von Willebrand factor, when platelet counts rise above 1000G/L. The mainstay of management consists on preventing hemostatic complications, by antiplatelet and/or anticoagulant treatment and myelosuppressive agents in high-risk patients.Circumstances related to a high thrombohemorrhagic risk, such as pregnancy and the perioperative period, prompt for specific management with regards to anticoagulation and myelosuppression treatment type. In order to apply a patient-specific treatment strategy, there is a need for a risk score assessment tool encompassing clinical parameters and hemostasis biomarkers.

Public Awareness on Cancer-Associated Thrombosis among the Greek Population: First Findings from the ROADMAP-CAT Awareness Study.

Background Cancer-associated thrombosis (CAT) is the second cause of mortality after cancer itself. CAT is underestimated as a health challenge among oncologists, whereas the levels of awareness among patients and the public have not been systematically assessed and followed in the European Union countries. Aim The Prospective Risk Assessment and Management of Patient with CAT (ROADMAP-CAT) Awareness study is an investigator-initiated, descriptive and nonexperimental study with a cross-sectional design and it explores CAT risk awareness among cancer patients and the general public in Greece to provide an impetus for health policy interventions and a benchmark against which impact of any future interventions may be assessed. Methods A total of 1,003 participants aged above 18 years were contacted by phone after random selection from the national telephone catalogue. Participation was voluntary and completely anonymous, and a structured questionnaire was used to elicit responses. Data were analyzed using IBM SPSS version 25. Results Among respondents, almost one-third (32.3%) reported CAT awareness, while only one in five (21.7%) were aware of the signs and symptoms of venous thromboembolism (VTE). Among patients with a personal history of cancer or of VTE, 47 and 58%, respectively, were aware of CAT risk. Of those aware of the association, 35.2% identified their treating physician as the main source of information. The level of awareness did not significantly differ by responders' demographics. Conclusion The ROADMAP-CAT Awareness study revealed very low levels of awareness on CAT and VTE risk both among the general public and cancer patients in Greece. Awareness of the signs and symptoms of VTE was also particularly low. Treating physicians are not actively engaging in educating their patients about CAT. Public awareness of the increased risk of VTE among cancer patients is critical to prevent and diagnose the disease early. It is imperative that a structured campaign supports medical professionals to take the time to increase awareness and educate their patients on this matter if to improve morbidity and mortality of cancer patients.

The COVID-19 Pandemic and the Need for an Integrated and Equitable Approach: An International Expert Consensus Paper.

BACKGROUND: One year after the declaration of the coronavirus disease 2019 (COVID-19) pandemic by the World Health Organization (WHO) and despite the implementation of mandatory physical barriers and social distancing, humanity remains challenged by a long-lasting and devastating public health crisis. MANAGEMENT: Non-pharmacological interventions (NPIs) are efficient mitigation strategies. The success of these NPIs is dependent on the approval and commitment of the population. The launch of a mass vaccination program in many countries in late December 2020 with mRNA vaccines, adenovirus-based vaccines, and inactivated virus vaccines has generated hope for the end of the pandemic. CURRENT ISSUES: The continuous appearance of new pathogenic viral strains and the ability of vaccines to prevent infection and transmission raise important concerns as we try to achieve community immunity against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and its variants. The need of a second and even third generation of vaccines has already been acknowledged by the WHO and governments. PERSPECTIVES: There is a critical and urgent need for a balanced and integrated strategy for the management of the COVID-19 outbreaks organized on three axes: (1) Prevention of the SARS-CoV-2 infection, (2) Detection and early diagnosis of patients at risk of disease worsening, and (3) Anticipation of medical care (PDA). CONCLUSION: The "PDA strategy" integrated into state policy for the support and expansion of health systems and introduction of digital organizations (i.e., telemedicine, e-Health, artificial intelligence, and machine-learning technology) is of major importance for the preservation of citizens' health and life world-wide.

Overview of risk assessment models for venous thromboembolism in ambulatory patients with cancer.

A B S T R A C T Important progress has been made in the development of risk assessment models (RAM) for the identification of outpatients on anticancer treatment at risk of venous thromboembolism (VTE). Since the breakthrough publication of the original Khorana risk score (KRS) more than 10 years ago, a new generation of KRS-based scores have been developed, including the Vienna Cancer and Thrombosis Study, PROTECHT, CONKO, ONCOTEV, TicOnco and the CATS/MICA score. Among these the CATS/MICA score showed that a simplified score composed of only two calibrated predictors, the type of cancer and the D-dimer levels, offers a user-friendly tool for the evaluation of cancer-associated thrombosis (CAT) risk. The COMPASS-CAT score is the first that introduced a more synthetic approach of risk evaluation by combining cancer-related predictors with patient comorbidity in a score which is designed for the types of cancer frequently seen in the community (i.e. breast, lung colon or ovarian cancers) and has been externally validated in independent studies. The Throly score is registered as part of the same group as it has a similar structure to the COMPASS-CAT score and is applicable in patients with lymphoma. The incorporation of specific biomarkers of hypercoagulability to the RAM for CAT offers the possibility to perform a precision medicine approach in the prevention of CAT. The improvement of RAM for CAT with artificial intelligence methodologies and deep learning techniques is the challenge in the near future.

Extracellular vesicles derived from pancreatic cancer cells BXPC3 or breast cancer cells MCF7 induce a permanent procoagulant shift to endothelial cells.

The endothelium could be a potential target of cancer cell derived extracellular vesicles (CaCe-dEV). We investigated in vitro the effect of CaCe-dEV on the hemostatic balance of endothelial cells. Extracellular vesicles released from pancreas adenocarcinoma cells (BXPC3) or human breast cancer cells (MCF7) were isolated by differential centrifugation. Human umbilical vein endothelial cells (HUVEC) were cultured for 72 h in the presence or absence of CaCe-dEV. Subsequently, they were washed and re-cultivated over three cycles to get daughter cell generations (DG) which were not exposed to CaCe-dEV. Thrombin generation of normal platelet poor plasma (PPP) added in wells carrying HUVEC was assessed by the Calibrated Automated Thrombogram®. Tissue factor activity (TFa) and procoagulant phospholipid clotting time were assessed. Some traces of TFa were displayed by non-exposed HUVEC (0.18 ±â€¯0.03 pM) and their EVs (1.2 ±â€¯1.0 pM). Non-exposed HUVEC did not induce any detectable thrombin generation. BXPC3-dEV displayed significantly higher TFa as compared to MCF7-dEV (45 ±â€¯5 pM versus 4.6 ±â€¯2.3pM respectively; p < 0.05). HUVEC exposed to CaCe-dEV enhanced thrombin generation. BXPC3-dEV induced significantly higher thrombin generation as compared to those exposed to MCF7-dEV. The procoagulant properties of HUVEC, acquired upon exposure to CaCe-dEV were transferred to DG. In conclusion, CaCe-dEV lead to a procoagulant shift of endothelial cells which, upon exposure, display TFa and enhance thrombin generation which is transferred to DG of HUVEC. The potency of CaCe-dEV to induce procoagulant shift of HUVEC depends on the histological type of the cancer cells. The procoagulant shift of endothelial cells which is transferable to DG could be an additional mechanism - together with cancer-induced blood hypercoagulability - in the pathogenesis of cancer associated thrombosis.

Modelization of Blood-Borne Hypercoagulability in Myeloma: A Tissue-Factor-Bearing Microparticle-Driven Process.

Introduction Hypercoagulability is a common blood alteration in newly diagnosed chemotherapy naïve patients with multiple myeloma. The identification of the procoagulant potential of cancer cells, which is principally related to tissue factor (TF) expression, attracts particular interest. The mechanisms by which myeloma plasma cells (MPCs) activate blood coagulation have been poorly investigated. Aim To identify the principal actors related with MPCs that boost thrombin generation (TG). Methods TF and annexin V expression by MPCs and MPC-derived microparticles (MPC-dMPs) was analyzed by flow cytometry. TF activity (TFa) and TF gene expression were also determined. TG in the presence of MPCs or MPC-dMPs was assessed with the calibrated automated thrombogram assay (CAT) in normal human PPP and in plasma depleted of factor VII or XII. TG was also assessed in plasma spiked with MPCs and MPC-dMPs. Results MPC-dMPs expressed approximately twofold higher levels of TF as compared with MPCs. The TFa expressed by MPC-dMPs was significantly higher compared with that expressed by MPCs. MPCs and MPC-dMPs enhanced TG of human plasma. TG was significantly higher with MPC-dMPs compared with MPCs. Conclusion MPCs indirectly induce blood-borne hypercoagulability through the release of MPC-dMPs rich in TF. Since MPCs, expressing low TFa, represent a weak procoagulant stimulus, the hypercoagulability at the microenvironment could be the resultant of MPC-dMPs rich in TF.

Erratum: Treatment of Cancer-Associated Thrombosis: Beyond HOKUSAI.

[This corrects the article DOI: 10.1055/s-0039-1696659.].

Treatment of Cancer-Associated Thrombosis: Beyond HOKUSAI.

Direct oral anticoagulants (DOACs) represent an attractive alternative to low-molecular-weight heparins (LMWHs) for the long-term treatment of cancer-associated thrombosis (CT) since they avoid the burden of daily injections. Analyses in subgroups of cancer patients from large randomized trials suggested that DOACs were at least as effective as vitamin K antagonists, while indirect comparisons suggested that DOACs' efficacy and safety profile were comparable to those of LMWHs. In the randomized controlled HOKUSAI-VTE Cancer study, currently the only completed phase III trial on DOACs in CT patients, edoxaban was shown noninferior to dalteparin on the composite primary endpoint of time to first recurrent venous thromboembolism or major bleeding during the 12 months after randomization. Study results suggest that both agents had comparable benefit/risk ratio in patients with CT. Even though this conclusion was valid from a strict statistical viewpoint, it was potentially misleading when interpreting benefit/risk ratios. Besides the obvious heterogeneity of the study population (e.g., 23% of patients no longer had cancer) and significantly different treatment durations between arms, secondary outcomes for efficacy were in favor of edoxaban for recurrent deep-vein thrombosis but not for recurrent pulmonary embolism, and major bleeding episodes were significantly more frequent in the edoxaban group, with an excess of gastrointestinal (GI) bleeding episodes observed mainly but not only in patients with GI cancers. More research is needed regarding specific patients' profiles, cancer types, and treatment period to better clarify the respective roles of DOACs and LMWHs in CT patients.

Longer procoagulant phospholipid-dependent clotting time, lower endogenous thrombin potential and higher tissue factor pathway inhibitor concentrations are associated with increased VTE occurrence in patients with newly diagnosed multiple myeloma: results of the prospective ROADMAP-MM-CAT study.

Venous thromboembolism (VTE) is a common complication in newly diagnosed symptomatic multiple myeloma (NDMM) patients. We explored cellular and plasma hypercoagulability in NDMM patients to identify relevant biomarkers that can be used in combination with clinical factors in the development of a risk assessment model (RAM) for VTE. Untreated patients (n = 144) with NDMM were prospectively enrolled, baseline biomarkers prior to anti-myeloma treatment and thromboprophylaxis initiation were obtained. These were compared against values in a group of healthy individuals with similar age and sex distribution. The primary study end point was symptomatic VTE occurrence. At 12-month follow-up cumulative VTE rate was 10.4%. NDMM patients showed biological signs of cellular and plasma hypercoagulability and endothelial cell activation. Procoagulant phospholipid clotting time (Procoagulant-PPL) was shorter, P-selectin levels lower and thrombin generation attenuated overall compared to healthy subjects. Longer Procoag-PPL®, lower endogenous thrombin potential (ETP), and higher levels of tissue factor pathway inhibitor (TFPI) were associated with VTE occurrence. Multivariate analysis showed that Procoag-PPL® and ETP were independent risk factors for VTE. We conclude that Procoag-PPL® and ETP can be prospectively incorporated into a RAM for VTE in MM in combination with clinical and disease risk factors.

Disseminated Intravascular Coagulation: An Update on Pathogenesis, Diagnosis, and Therapeutic Strategies.

Disseminated intravascular coagulation (DIC) is an acquired clinicobiological syndrome characterized by widespread activation of coagulation leading to fibrin deposition in the vasculature, organ dysfunction, consumption of clotting factors and platelets, and life-threatening hemorrhage. Disseminated intravascular coagulation is provoked by several underlying disorders (sepsis, cancer, trauma, and pregnancy complicated with eclampsia or other calamities). Treatment of the underlying disease and elimination of the trigger mechanism are the cornerstone therapeutic approaches. Therapeutic strategies specific for DIC aim to control activation of blood coagulation and bleeding risk. The clinical trials using DIC as entry criterion are limited. Large randomized, phase III clinical trials have investigated the efficacy of antithrombin (AT), activated protein C (APC), tissue factor pathway inhibitor (TFPI), and thrombomodulin (TM) in patients with sepsis, but the diagnosis of DIC was not part of the inclusion criteria. Treatment with APC reduced 28-day mortality of patients with severe sepsis, including patients retrospectively assigned to a subgroup with sepsis-associated DIC. Treatment with APC did not have any positive effects in other patient groups. The APC treatment increased the bleeding risk in patients with sepsis, which led to the withdrawal of this drug from the market. Treatment with AT failed to reduce 28-day mortality in patients with severe sepsis, but a retrospective subgroup analysis suggested possible efficacy in patients with DIC. Clinical studies with recombinant TFPI or TM have been carried out showing promising results. The efficacy and safety of other anticoagulants (ie, unfractionated heparin, low-molecular-weight heparin) or transfusion of platelet concentrates or clotting factor concentrates have not been objectively assessed.

Prospective Assessment of Clinical Risk Factors and Biomarkers of Hypercoagulability for the Identification of Patients with Lung Adenocarcinoma at Risk for Cancer-Associated Thrombosis: The Observational ROADMAP-CAT Study.

BACKGROUND: The aim of this prospective study was to identify the most clinically relevant hypercoagulability biomarkers in lung adenocarcinoma patients for elaboration of an improved risk assessment model (RAM) for venous thromboembolism (VTE). SUBJECTS, MATERIALS, AND METHODS: One hundred fifty ambulatory patients with lung adenocarcinoma were prospectively enrolled. Thrombin generation, procoagulant phospholipid-dependent clotting time (Procoag-PPL), tissue factor activity (TFa), factor VIIa (FVIIa), factor V (FV), antithrombin, D-Dimers, P-selectin, and heparanase levels were assessed in platelet-poor plasma at inclusion (baseline) and at the end of the third chemotherapy cycle (third chemotherapy). Cox regression analysis was used to identify independent VTE predictors. RESULTS: At baseline, patients had significantly attenuated thrombin generation, shorter Procoag-PPL, higher levels of TFa, D-Dimers, and heparanase, and lower levels of FVIIa and P-selectin, compared with controls. A significant increase in Procoag-PPL, FV, and FVIIa and a decrease of P-selectin levels were observed between baseline and third chemotherapy. Hospitalization within the last 3 months prior to assessment, time since cancer diagnosis less than 6 months, mean rate index (MRI) of thrombin generation, and Procoag-PPL were independently associated with symptomatic VTE. Accordingly, a prediction model including Procoag-PPL and MRI showed significant discriminating capacity (area under the curve: 0.84). CONCLUSION: Ambulatory patients with lung adenocarcinoma may display pronounced blood hypercoagulability due to decreased Procoag-PPL, increased endothelial cell activation, and increased degradation of fibrin. Incorporation of Procoag-PPL and MRI of thrombin generation may improve the accuracy of a VTE-RAM in the above setting. IMPLICATIONS FOR PRACTICE: The prospective ROADMAP-CAT study identified two biomarkers of hypercoagulability, the procoagulant phospholipid-dependent clotting time (Procoag-PPL) and the mean rate index (MRI) of the propagation phase of thrombin generation assessed with the Calibrated Automated Thrombinoscope, as being clinically relevant for the classification of ambulatory patients with lung adenocarcinoma receiving a maximum of one cycle of chemotherapy into high and intermediate/low risk for venous thromboembolism. Measurement of Procoag-PPL and MRI within 1 month after the administration of the first chemotherapy cycle provides significant accuracy of the assessment. Association of the Procoag-PPL and MRI with the clinical risk assessment model for cancer-associated thrombosis in ambulatory patients with solid tumors (COMPASS-CAT RAM) further improved its accuracy.

Graft Product for Autologous Peripheral Blood Stem Cell Transplantation Enhances Thrombin Generation and Expresses Procoagulant Microparticles and Tissue Factor.

The beneficial effect of autologous peripheral blood stem cell transplantation (APBSCT) may be compromised by acute vascular complications related to hypercoagulability. We studied the impact of graft product on thrombin generation of normal plasma and the expression of tissue factor (TF) and procoagulant platelet-derived procoagulant microparticles (Pd-MPs) in samples of graft products. Graft products from 10 patients eligible for APBSCT were mixed with platelet-poor plasma (PPP) or platelet-rich plasma (PRP) from healthy volunteers and assessed for in vitro thrombin generation. In control experiments, thrombin generation was assessed in (1) PPP and PRP without any exogenous TF and/or procoagulant phospholipids, (2) PPP with the addition of TF (5 pM) and procoagulant phospholipids (4 µM), (3) in PRP with the addition of TF (5 pM). Graft products were assessed with Western blot assay for TF expression, with a specific clotting assay for TF activity and with flow cytometry assay for Pd-MPs. The graft product enhanced thrombin generation and its procoagulant activity was related to the presence of Pd-MPs and TF. The concentration of Pd-MPs in the graft product was characterized by a significant interindividual variability. The present study reveals the need for a thorough quality control of the graft products regarding their procoagulant potential.

Differential contribution of tissue factor and Factor XII to thrombin generation triggered by breast and pancreatic cancer cells.

Most cancer cells trigger thrombin generation (TG) to various extent. In the present study, we dissected the mechanisms responsible for the procoagulant activity of pancreatic adenocarcinoma cells (BXPC3), a highly thrombogenic cancer type, and breast cancer cells (MCF7), a less thombogenic tumor type. TG of normal plasma was assessed by the Thrombinoscope (CAT®) in the presence or absence of cancer cells. TG was also assessed in plasma depleted of clotting factors, in plasma spiked with tissue factor (TF) and/or procoagulant phospholipids, in plasma spiked with an anti-TF monoclonal antibody or with corn trypsin inhibitor (CTI). The presence of alternatively spliced TF (asTF), TF activity (TFa) and cancer procoagulant (CP) levels were determined. TFa and asTF were highly expressed by BXPC3 cells, compared to MCF7 cells, while CP levels were higher in MCF7 cells. BXPC3 cells had a stronger effect on TG than MCF7 cells. Accordingly, anti-TF had more inhibitory activity on TG triggered by BXPC3 cells while CTI had more pronounced inhibitory effect on TG triggered by MCF7 cells. TG enhancement by both BXPC3 and MCF7 cells was mediated by FVII and intrinsic tenase while FXII and FXI were also important for MCF7 cells. The induction of TG by BXPC3 cells was mainly driven by the TF pathway while TG generation triggered by MCF7 cells was also driven by FXII activation. Therefore, hypercoagulability results from a combination of the inherent procoagulant properties of cancer cell-associated TF as well as of procoagulant phospholipids in the plasma microenvironment.

Procoagulant microparticles derived from cancer cells have determinant role in the hypercoagulable state associated with cancer.

Hypercoagulablity is a common alteration of blood coagulation in cancer patients. However, the procoagulant activity of cancer cells is not sufficient to induce hypercoagulability. The present study was aimed to identify the mechanism with which hypercoagulabilty is produced in the presence of cancer cells. We focused on the analysis of the procoagulant elements carried by cancer cell-derived microparticles (CaCe-dMP) and we evaluated the impact of microparticles associated with the cancer cells from which they stem on thrombin generation. CaCe-dMP from the cancer cells were isolated from the conditioned medium and analyzed for tissue factor (TF) and procoagulant phospholipid expression. Thrombin generation of normal plasma was assessed by the Thrombinoscope (CAT®) in the presence or absence of pancreas adeno-carcinoma cells (BXPC3) or breast cancer MCF7 cells supplemented with the respective CaCe-dMP. Both BXPC3 and MCF7 cells express abundant amounts of active TF. Phosphatidylserine was identified on the surface of CaCe-dMP, unlike the cancer cells themselves. The expression of TFa by the microparticles was significantly higher to that observed on the cancer cells. Culture of the cancer cells with their microparticles resulted in thrombin generation significantly higher as compared to the upper normal limit. In conclusion, cancer cells 'enrich' the microenvironment with procoagulant elements, especially procoagulant micro-particles which express TF and procoagulant phospholipids. The association of cancer cells with procoagulant microparticles is necessary for a state of hypercoagulability, at the level of the tumoral microenvironment. The intensity of the hypercoagulability depends on the histological type of the cancer cells.

A Predictive Score for Thrombosis Associated with Breast, Colorectal, Lung, or Ovarian Cancer: The Prospective COMPASS-Cancer-Associated Thrombosis Study.

BACKGROUND: The stratification of outpatients on chemotherapy for breast, colorectal, lung, and ovarian cancers at risk of venous thromboembolism (VTE) remains an unmet clinical need. The derivation of a risk assessment model (RAM) for VTE in these patients was the aim of the study "Prospective Comparison of Methods for thromboembolic risk assessment with clinical Perceptions and AwareneSS in real life patients-Cancer Associated Thrombosis" (COMPASS-CAT). PATIENTS AND METHODS: The derivation cohort consisted of 1,023 outpatients. Patients on low molecular weight heparin (LMWH) thromboprophylaxis were excluded. Documented symptomatic VTE was the endpoint of the study. RESULTS: Patients had breast (61%), colorectal (17%), lung (13%), or ovarian cancer (8.6%) at localized (30%) or advanced stage (70%). In 64% of patients, cancer was diagnosed within the last 6 months prior to inclusion. Most of them were on chemotherapy when assessed. Symptomatic VTE occurred in 8.5% of patients. The COMPASS-CAT RAM includes the following variables: (a) anthracycline or anti-hormonal therapy, (b) time since cancer diagnosis, (c) central venous catheter, (d) stage of cancer, (e) presence of cardiovascular risk factors, (f) recent hospitalization for acute medical illness, (g) personal history of VTE, and (h) platelet count. At 6 months, patients stratified at low/intermediate and high-risk groups had VTE rates of 1.7% and 13.3%, respectively. The area under the curve of receiver operating characteristics analysis was 0.85. The sensitivity and specificity of the RAM were 88% and 52%, respectively. The negative and positive predictive values of the RAM were 98% and 13%, respectively. CONCLUSION: The COMPASS-CAT RAM includes reliable and easily collected VTE risk predictors and, in contrast to the Khorana score, it is applicable after the initiation of anticancer treatment in patients with common solid tumors. Its robustness for stratification of patients at high and low/intermediate VTE risk needs to be externally validated. IMPLICATIONS FOR PRACTICE: The Prospective Comparison of Methods for thromboembolic risk assessment with clinical Perceptions and AwareneSS in real life patients-Cancer Associated Thrombosis (COMPASS-CAT) study provides a new risk assessment model (RAM) for venous thromboembolism (VTE) applicable in outpatients with breast, colorectal, lung or ovarian cancer. The COMPASS-CAT RAM is robust, applicable during chemotherapy and determines the need for VTE prévention by including reliable and easily collected VTE predictors associated with cancer status, its treatment as well as with patients' characteristics and comorbidities. An independent external validation of the RAM is indicated before its use in clinical practice.

The Antithrombotic Potential of Tinzaparin and Enoxaparin Upon Thrombin Generation Triggered In Vitro by Human Ovarian Cancer Cells IGROV1.

BACKGROUND: A documented relationship between ovarian cancer and thrombosis does exist. Low-molecular-weight heparins (LMWHs) are cornerstone drugs in the primary prevention and treatment of venous thromboembolic events in patients with cancer. However, cancer cells may alter the efficiency of these antithrombotic agents. OBJECTIVE: We aimed to characterize the procoagulant phenotype of human epithelial ovarian adenocarcinoma cells, IGROV1, and to compare the capacity of tinzaparin and enoxaparin to inhibit thrombin generation triggered by these cells. METHODS: Thrombin generation induced by different concentrations of IGROV1 cells on platelet poor plasma (PPP) was assessed by the calibrated automated thrombogram assay. Tissue factor (TF) expression was studied using Western blot analysis. Then, the experimental model of thrombin generation was used to compare the inhibitory effect of clinically relevant concentrations of both tinzaparin and enoxaparin. The inhibitory concentration 50 (IC50) of the mean rate index and the endogenous thrombin potential and the 2-fold increase in lag time were analyzed on the basis of the anti-Xa and anti-IIa activities of the LMWHs. RESULTS: IGROV1 cells suspended into PPP resulted in a significant increase in thrombin generation in the absence of any exogenous source of TF and phospholipids. Tissue factor was expressed by IGROV1 cells. Tinzaparin was a more potent inhibitor of thrombin generation than enoxaparin. The inhibition of thrombin generation induced by IGROV1 cancer cells depended mainly on the anti-Xa activity of the LMWHs. CONCLUSION: This experimental study in ovarian cancer cells demonstrates that the antithrombotic activity of LMWHs is not completely predicted by the anti-Xa or anti-IIa activities measured in PPP.

The Role of Tissue Factor in Cancer-Related Hypercoagulability, Tumor Growth, Angiogenesis and Metastasis and Future Therapeutic Strategies.

It is widely recognized that a strong correlation exists between cancer and aberrant hemostasis. Patients with various types of cancers often develop thrombosis, a phenomenon commonly referred to as Trousseau syndrome. Tissue factor (TF) is expressed by tumor cells and contributes to a variety of pathologic processes, such as thrombosis, tumor growth, tumor angiogenesis, and metastasis. Tissue factor is expressed in two naturally occurring protein isoforms: membrane-bound full-length TF (flTF) and soluble alternatively spliced TF (asTF). Tissue factor is the primary initiator of blood coagulation, and it triggers intracellular signaling through protease-activated receptors (PARs). PARs are activated either by TF/FVIIa complexes or by thrombin generated following coagulation activation. Furthermore, the noncoagulant asTF retains an integrin-binding site and stimulates angiogenesis by ligating endothelial integrins αvß3 and α6ß1. Lastly, the increased TF expression in tumors is associated with the release in blood of TF-positive procoagulant microparticles that favor thromboembolic complications. Therefore, the interruption of asTF and flTF signaling represents a potential antiangiogenic strategy. In this review, we summarize the current knowledge on the role of TF in cancer, and we explore therapeutic perspectives based on TF targeting.

[Risk of venous thromboembolism in cancer patients: Reality, actuality and perspectives]. / Risque thromboembolique en oncologie : réalités, actualités et perspectives.

Cancer is a leading cause of venous thromboembolism (VTE) and vice versa. Pulmonary embolism is the second cause of death in cancer patients. Tumor progression is associated with coagulation activation. The pathogenesis of thrombosis during cancer is particularly complex stemming from multiple connections of this disease with both systems of inflammation and hemostasis. The risk of VTE depends on cancer type and the stage of the disease, the anticancer treatments and the time since cancer diagnosis as well as on the presence of patient-related risk factors (i.e. age, obesity, previous history of VTE, underlying diseases…). The presence of other precipitating factors and the duration of the exposure to them are also key elements in the assessment of such a thrombotic risk. It is therefore important to identify all the VTE risk factors to identify patients at high vascular risk and to determine the period during which this risk is significantly increased. The integration of biomarkers of hypercoagulability in proposed risk assessment models for VTE will improve their capacity to identify patients eligible for pharmacological thromboprophylaxis. In this review, we report the current status of knowledge on the connection between cancer and hypercoagulability, the numerous risk factors for VTE must be identified in cancer patients and the best methodology to build a more accurate assessment of this vascular risk in such a complex medical context.

Heparin resistance and coagulation activation rebound effect after anticoagulant withdrawal: beneficiary effect of adjuvant antiplatelet therapy.

BACKGROUND: Aim. The aim of this study was to investigate biological resistance to enoxaparin and rebound effect after prophylaxis withdrawal, using thrombin generation (TG) assay. METHODS: Fifteen-patients undergoing femoro-popliteal bypass grafting (enoxaparin 4000 antiXaIU+75 mg clopidogrel), and 15-patients undergoing total-hip-replacement (THR) (enoxaparin alone). TG-assay parameters (lag-time, endogenous-thrombin-potential, peak-, time-to-peak, and Mean-Rate-Index) were assessed to investigate heparin resistance and rebound effect after prophylaxis interruption. Measurements were obtained preoperative, postoperative (before prophylaxis initiation), 8-days postoperative, and 48-hours after anticoagulant withdrawal (day 32). RESULTS: Surgery increased TG in vascular-patients despite intra-operative unfractioned heparin administration when compared to orthopedic patients (MRI:P=0.039, ETP:P=0.001, PGT:P=0.003), but this perioperative prothrombotic status was reversed by postoperative thromboprophylaxis. No thromboembolic events were observed. Similar TG parameter values between the 8th and 32nd postoperative day indicate that vascular patients were adequately protected after prophylaxis withdrawal, probably due to the synergic action of clopidogrel, while orthopedic patients increased TG on day-32 compared to the 8th postoperative day (P=0.03, for both lag-time and ttPeak). Furthermore, on day-32, a prothrombotic status (increased TG) was observed in the orthopedic patients (P=0.034, and 0.004 for ttPeak and lag-time, respectively). Inter-individual variability to enoxaparin response was observed in both groups:7/15 vascular and 10/15 orthopedic patients increased TG despite anticoagulant administration, which reveals heparin-resistance. Among the heparin-resistant patients, 4 vascular and 6 orthopedic increased TG after anticoagulant withdrawal, depicting a rebound effect to activation of coagulation. CONCLUSIONS: Heparin-resistance is not a rare phenomenon in clinical practice and was found in about half of our patients. A rebound effect of coagulation activation after thromboprophylaxis withdrawal is observed in the extended postoperative period. This phenomenon is attenuated with the addition of concomitant antiplatelet (clopidogrel) treatment.

Cancer cells BXPC3 and MCF7 differentially reverse the inhibition of thrombin generation by apixaban, fondaparinux and enoxaparin.

INTRODUCTION: Cancer cells may alter the efficiency of the antithrombotic agents. To explore this possibility, the present study compared the capacity of the LMWH enoxaparin and the specific inhibitors of Xa (apixaban and fondaparinux) to inhibit thrombin generation triggered by pancreas adenocarcinoma cells (BXPC3) and human breast carcinoma cells (MCF7). MATERIALS AND METHODS: Samples of platelet poor (PPP) or platelet rich plasma (PRP) spiked with apixaban, fondaparinux or enoxaparin were added in micro wells carrying cancer cells and assessed for thrombin generation. In the control experiment thrombin generation was triggered with tissue factor reagent. RESULTS: The three antithrombotics inhibited thrombin generation in a concentration dependent manner. The BXPC3 and MCF7 cells reversed in a different intensity the effect of the studied agents. According to the histological type of the cancer the antithrombotic efficiency of apixaban was preserved or partially reversed. Fondaparinux, was more vulnerable to the presence of cancer cells as compared to apixaban. The effect of BXCP3 or MCF7 cells on the antithrombotic potency of enoxaparin was of similar magnitude as that on apixaban. CONCLUSIONS: The type of cancer cells is determinant for the antithrombotic efficiency of the specific factor Xa inhibitors. In contrast it does not significantly influence the potency of enoxaparin. The present study shows that the impact of the type of cancer cells on the antithrombotic activity of the specific Xa inhibitors should not be neglected. This has to be taken into consideration for the design of dose-finding studies of the direct orally active FXa inhibitors in patients with different histological types of cancer.