Thrombotic storm, hemostasis disorders and thromboinflammation in COVID-19

The rate of thrombosis and disseminated intravascular coagulation (DIC) has been increasing in COVID-19 patients. Key features related to such condition include minimal or no risk of bleeding, moderate thrombocytopenia, high plasma fibrinogen as well as complement components level in the areas of thrombotic microangiopathy. The clinical picture is not typical for classic DIC. This review systematizes the pathogenetic mechanisms of hypercoagulation in sepsis and its extreme forms in patients with COVID-19. The latter consist of the thrombosis-related immune mechanisms, the complement activation, the macrophage activation syndrome, the formation of antiphospholipid antibodies, the hyperferritinemia, and the dysregulation of the renin-angiotensin system. Taking into consideration the pathogenetic mechanisms, the biomarkers had been identified related to the prognosis of the disease development. Patients with pre-existing cardiovascular disease and other risk factors, including obesity, diabetes, hypertension, and aging pose the peak risk of dying from COVID-19. We also summarize new data on platelet and endothelial dysfunction, immunothrombosis, and, as a result, thrombotic storm as essential components of COVID-19 severe features

New orally active anticoagulant agents for the prevention and treatment of venous thromboembolism in cancer patients

International audiencePatients with cancer have a 6–7-fold higher risk of venous thromboembolism (VTE) as compared with non-cancer patients. Effective and safe anticoagulation for the prevention and treatment of VTE is the cornerstone of the management of patients with cancer, aiming to decrease morbidity and mortality and to improve quality of life. Unfractionated heparin, low molecular weight heparins, fondaparinux and vitamin K antagonists (VKAs) are used in the prevention and treatment of VTE in cancer patients. Heparins and fondaparinux are administered subcutaneously. VKAs are orally active, but they have a narrow therapeutic window, numerous food and drug interactions, and treatment requires regular laboratory monitoring and dose adjustment. These limitations among others have important negative impact on the quality of life of patients and decrease adherence to the treatment. New orally active anticoagulant (NOAC) agents are specific inhibitors of activated factor Xa (FXa) (rivaroxaban and apixaban) or thrombin (dabigatran). It is expected that NOACs will improve antithrombotic treatment. Cancer patients are a particular group that could benefit from treatment with NOACs. However, NOACs present some significant interactions with drugs frequently used in cancer patients, which might influence their pharmacokinetics, compromising their efficacy and safety. In the present review, we analyzed the available data from the subgroups of patients with active cancer who were included in Phase III clinical trials that assessed the efficacy and safety of NOACs in the prevention and treatment of VTE. The data from the Phase III trials in prophylaxis of VTE by rivaroxaban or apixaban highlight that these two agents, although belonging to the same pharmacological group (direct inhibitors of factor Xa), have substantially different profiles of efficacy and safety, especially in hospitalized acutely ill medical patients with active cancer. A limited number of patients with VTE and active cancer were included in the Phase III trials (EINSTEIN, AMPLIFY, and RECOVER) which evaluated the efficacy and safety of NOACs in the acute phase and secondary prevention of VTE. Although, from a conceptual point of view, NOACs could be an attractive alternative for the treatment of VTE in cancer patients, the available data do not support this option. In addition, due to the elimination of the NOACs by the liver and renal pathway as well as because of their pharmacological interactions with drugs which are frequently used in cancer patients, an eventual use of these drugs in cancer patients should be extremely cautious and be restricted only to patients presenting with contraindications for low molecular weight heparins, fondaparinux, or VKAs. The analysis of the available data presented in this review reinforces the request for the design of new Phase III clinical trials for the assessment of the efficacy and safety of NOACs in specific populations of patients with cancer

Combined Vaccination Approaches for COVID-19. Will These Improve the Efficacy Spectrum?

International audienc

Cryofibrinogenemia: new insights into clinical and pathogenic features.

International audienceOBJECTIVE: Cryofibrinogenemia is an under-recognized cryoprotein that can be life-threatening when untreated. Our aim was to describe the prevalence and clinical findings of patients with cryofibrinogenemia and to clarify the mechanisms involved. METHODS: Between 1996 and 2006, 2312 patients were tested for cryofibrinogenemia in a single university hospital. A total of 515 patients had positive test results, of whom 455 (88.3%) had an associated cryoglobulin. RESULTS: Sixty patients (11.7%) with persistent cryofibrinogenemia and without cryoglobulin were included in the study. Main clinical manifestations related to cryofibrinogenemia included purpura (46.6%), skin necrosis (36.6%), and arthralgia (31.6%) with cold sensitivity in 40%. Overall thrombotic events occurred in up to 40% of cases. Cryofibrinogen plasma concentration was 2 times greater in patients with thrombotic events (P=.012). Complications included gangrene (5%), septicemia (5%), and leg amputation (3.3%). Complete remission of cryofibrinogenemia was achieved in 78% of patients receiving antithrombotic agents, steroids, or immunosuppressants, whereas 41.6% of patients experienced a relapse after a median time of 9 months (range 7-42 months). After a mean follow-up of 85 months, 3 patients died of sepsis (n=2) and cardiovascular disease (n=1). Fibrinolysis status analyzed in a patient with cryofibrinogenemia showed an increase in fibrinolysis inhibitor levels, plasminogen activator inhibitor-1, alpha-2 macroglobulin, and euglobulin lysis time, which normalized after fibrinolytic therapy. CONCLUSION: Essential cryofibrinogenemia represents 12% of all the cryoproteins at Pitie-Salpêtriere Hospital. Thrombotic events are frequent and could be associated with the amount of plasma cryofibrinogen. Defects in the fibrinolysis process might lead to cryofibrinogen accumulation and clotting in small and medium arteries

Towards a standardization of thrombin generation assessment: The influence of tissue factor, platelets and phospholipids concentration on the normal values of Thrombogram-Thrombinoscope assay

Abstract Background Thrombin generation assay was developed several years ago to mimic physiological coagulation mechanisms but it had important limitations. Thrombogram-Thrombinoscope assay using a fluorogenic substrate, allows obtaining thrombin generation curves in non-defibrinated platelet rich plasma (PRP) in a fully automated manner. Methods We standardised the methodology of Thrombogram-Thrombinoscope and we evaluated the precision of thrombin generation parameters (lag-time, maximum concentration of thrombin [Cmax], time required to reach Cmax [Tmax] and endogenous thrombin potential ETP) using different concentrations of recombinant human tissue factor, platelets or phospholipids. Normal values of thrombin generation assay were established in optimal experimental conditions. Results In the presence of low TF concentrations (final dilution of thromboplastin in plasma: 1/1000–1/2000) the Thrombogram assay showed intra-assay and inter-assay coefficients of variation lower than 9%. Thrombin generation parameters showed an important inter-individual variability and the coefficients of variation ranged from 18% to 50%. In PRP the lag-time, Cmax and Tmax but not the ETP, were influenced by TF concentration. Thrombin generation parameters were not influenced by variations of platelet concentration from 50 × 109/l to 400 × 109/l. The addition of synthetic procoagulant phospholipids in PPP strongly influenced all the parameters of thrombogram. For all the parameters of thrombogram a threshold effect was observed in the presence of phspholipid concentrations equal or higher to 4 μM. In frozen-thawed PRP the lag-time and the Tmax were significantly reduced and the Cmax was increased compared to the fresh PRP, but the ETP, the intra assay and the inter-assay coefficients of variation were similar in both test-systems. Conclusion Thrombogram-Thrombinoscope assay performed in fresh or in frozen-thawed PRP has an acceptable precision, with low inter-assay and intra-assay coefficient of variations. The concentration of TF is determinant for the normal values of the studied parameters of thrombin generation. When the assay is performed in PPP, thrombin generation parameters are influenced by the concentration of procoagulant synthetic phospholipids. The optimal experimental conditions were obtained in the presence of 1/1000 final dilution of thromboplastin, a platelet count higher than 50 × 109/l and a synthetic phospholipid concentration higher than 4 μM.</p

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

International audienceThe 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 ± 0.03 pM) and their EVs (1.2 ± 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 ± 5 pM versus 4.6 ± 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