Barbara Eifrig

Tissue factor procoagulant activity of plasma microparticles in patients with cancer-associated disseminated intravascular coagulation.

Tissue factor (TF) expressed on sub-cellular membrane vesicles, so-called plasma microparticles (MPs), has recently emerged as a potential key player in intravascular coagulation activation in various disease states. In this report, we demonstrate significantly increased levels of TF-specific procoagulant activity (PCA) of plasma MPs in five patients presenting with overt disseminated intravascular coagulation (DIC) due to an underlying malignancy, including non-small-cell lung cancer (n = 1), melanoma (n = 1), prostate cancer (n = 2), and acute promyelocytic leukemia (n = 1). Clotting experiments on available tumor cell samples suggested that cancer cells were a potential source of circulating TF-positive MPs at least in three of the five patients. Furthermore, follow-up plasma samples from two surviving patients revealed that response of their malignancies to specific anti-cancer therapy was paralleled by resolution of overt DIC and a significant decline in MP-associated TF PCA. Levels of plasma TF antigen, as assessed by an enzyme-linked immunosorbent assay, were also increased at presentation albeit to a lesser extent compared to MP-associated TF PCA, likely due to insufficient solubilization of the phospholipid-incorporated full-length TF molecule by the detergent. In summary, our findings suggest that MP-associated TF PCA may play an important pathogenic role in the evolution of overt DIC in various types of malignancy.

Tissue factor procoagulant activity of plasma microparticles is increased in patients with early-stage prostate cancer

Tissue factor (TF) plays a critical role in tumour growth and metastasis, and its enhanced release into plasma in association with cellular microparticles (MPs) has recently been associated with pathological cancer progression. We have previously demonstrated significantly elevated levels of plasma TF antigen as well as systemic coagulation and platelet activation in patients with localised prostate cancer. In this prospective study, we used a highly sensitive one-stage clotting assay to measure preoperative TF-specific procoagulant activity (PCA) of plasma MPs in 68 consecutive patients with early-stage prostate cancer to further explore the relevance of circulating TF in this tumour entity. Automated calibrated thrombography was used to monitor thrombin generation in cell-free plasma samples in the absence of exogenous TF or phospholipids. Compared to healthy male controls (n=20), patients had significantly increased levels of both D-dimer and TF-specific PCA of plasma MPs (p<0.001). Furthermore, MP-associated TF PCA was higher in patients with (n=29) than in those without (n=39) laboratory evidence of an acute-phase reaction (p=0.004) and decreased to normal levels within one week after radical prostatectomy. Overall, we found a significant correlation between TF-specific PCA of plasma MPs and plasma D-dimer (p=0.002), suggesting that plasma MPs contributed to in-vivo coagulation activation in a TF-dependent manner. Thrombin generation in plasma was also significantly increased in patients compared to controls (p<0.01). Collectively, our findings suggest that TF-specific PCA of plasma MPs contributes to intravascular coagulation activation in patients with early-stage prostate cancer and may represent a potential link between hypercoagulability, inflammation, and disease progression.

Plasma tissue factor antigen in localized prostate cancer: Distribution, clinical significance and correlation with haemostatic activation markers

Tissue factor (TF) is involved in cancer growth and metastasis, and haemostatic abnormalities are found in most patients with advanced malignancies, including prostate cancer (PC). Because anti-haemostatic agents are increasingly screened for their potential to prolong survival in tumor patients, a detailed characterization of haemostatic markers in selected cancer subtypes and clinical stages is warranted. In this study, we measured preoperative plasma TF antigen in a large cohort of patients with localized PC and correlated its levels with markers of coagulation and platelet activation, prostate-specific antigen (PSA), and histopathological findings to explore its potential as a prognostic marker in this tumor entity. Out of 140 patients, 19% and 23% had plasma TF antigen levels of <40 pg/ml (low-TF) and >200 pg/ml (high-TF), respectively, which was substantially higher than in 42 healthy male controls. Patients also had low-grade systemic coagulation activation as evidenced by elevated D-dimer, F1 + 2, and PAP plasma levels. Furthermore, similar to sP-selectin and sCD40L antigen, flow cytometric analysis of platelet-derived microparticles in plasma revealed significantly increased numbers in high-TF as compared to low-TF patients and controls. Whereas elevated D-dimer was associated with larger and less differentiated tumors, preoperative plasma TF antigen levels (median [IQR]) were higher in patients with (161 pg/ml [100-236]) than in those without recurrent PC (105 pg/ml [52-182]), as indicated by a serum PSA of >0.1 ng/ml during ambulatory follow-up. In patients with localized PC, preoperative plasma TF antigen levels correlate with platelet activation in vivo and may indicate an increased risk for recurrent disease.

An in vitro study on the mechanisms of coagulation activation in acute myelogenous leukemia (AML): role of tissue factor regulation by cytotoxic drugs and GM-CSF

AML patients may suffer from a disseminated coagulopathy, which can aggravate a pre-existing bleeding tendency due to thrombocytopenia and platelet dysfunction. The cellular and molecular mechanisms underlying this coagulopathy, however, are not completely understood. Indeed, the broad and increasing therapeutic use of cytotoxic drugs and growth factors is likely to contribute to the complexity of hemostatic abnormalities encountered in this hematologic malignancy. The nature of coagulation activation in AML was therefore investigated in vitro using the human leukemic cell line, HL60. Tissue factor (TF) was almost entirely located on the cell surface and bound factor VIIa, but only 15-25% of this TF was primarily functionally active. Treatment with increasing concentrations of daunorubicin or cytosine-beta-D-arabinofuranoside, two cytotoxic drugs commonly used in AML therapy, induced apoptosis and secondary necrosis of HL60 cells and resulted in marked decryption of TF PCA independent of de novo protein synthesis. This PCA-modulating effect was concomitant with and functionally dependent on the exposure of phosphatidylserine on the outer membrane leaflet. Similar observations were made in analogous ex vivo studies on patient-derived myeloblasts. Incubation of HL60 cells with GM-CSF, a cytokine expressed in the bone marrow microenvironment and used as an adjunct to AML treatment, evoked a cellular response, which included both enhanced TF production and release of VEGF-A and uPA into the culture medium. We conclude that both decryption of pre-formed TF PCA by chemotherapeutic drugs and de novo induction of TF by cytokines such as GM-CSF can regulate the pro-coagulant phenotype of HL60 cells in vitro.

Relationship between haemophilia and social status.

The impact of haemophilia and its treatment on social status has not been well studied, although research into the quality of life of patients with haemophilia has shed some light on aspects of social and role functioning. Studies conducted before the advent of safe and effective coagulation factor replacement therapy suggest that the haemophilia population was predominantly of low socioeconomic status with many social disadvantages, including high rates of disability and unemployment and low rates of marriage. Since the availability of purified factor VIII concentrates that could be used in a home-care setting and as prophylaxis, most research suggests that social status and well-being amongst children, adolescents, and adults with haemophilia is not compromised, and is comparable to that of the general population. Children and adolescents with haemophilia do not generally feel disadvantaged, although haemophilia-related issues at school and amongst peer groups do arise. Recent studies in adults show higher than average rates of marriage and cohabitation and the attainment of a generally good educational status, but, as in the past, employment rates remain comparatively lower. Social status amongst the elderly with haemophilia who may have developed severe disability as a result of their condition is poorly defined and has never been formally studied. Additional research is recommended.

Platelet Activation Markers in Patients with Venous Thromboembolism without Predisposing Factors

A constant in vitro hypersensitivity of platelets (adenosine diphosphate) has been suggested as a risk factor for arterial and even venous thrombosis. Our aim was to determine phenotypic and functional alterations of platelets by flow cytometry as potential prothrombotic risk factors in patients with a history of unexplained spontaneous venous thrombosis. Forty-nine patients with a history of spontaneous venous thrombosis and no inherited or acquired thrombophilic risk factors were compared with a reference group of 39 healthy volunteers. Flow cytometry (FACS) was used to analyze the surface expression of CD62 (P-selectin) and CD63 in nonactivated platelets and after in vitro stimulation with adenosine diphosphate and thrombin receptor activator peptide 6. Mean fluorescence intensity of CD62 and CD63 surface expression as well as percentage of CD62 and CD63 positive cells and binding index differed in patients with a history of thrombosis compared with the reference group, but failed to reach statistical significance. Similar results were observed after in vitrostimulation with adenosine diphosphate and thrombin receptor activator peptide 6. In conclusion, the expression of CD62 and CD63 of resting and in vitro activated platelets could not be established as a risk factor for spontaneous venous thromboembolism.

Thromboembolische Komplikationen – Prophylaxe und Therapie im Fokus

ZusammenfassungKrebspatienten haben ein erhöhtes Risiko für thromboembolische Komplikationen, die gemeinhin unter dem Begriff des Trousseau-Syndroms zusammengefasst werden. Neben der malignen Grunderkrankung, die mit dramatischen Veränderungen von systemischer Blutgerinnung und Fibrinolyse einhergehen kann, spielen Supportivmaßnahmen und spezifische Krebstherapien wie Operation oder Chemotherapie in der Pathophysiologie der tumorassoziierten venösen Thromboembolie (VTE) eine bedeutende Rolle. Klinische Studien haben gezeigt, dass in der medikamentösen Therapie der tumorassoziierten VTE eine Langzeitbehandlung mit niedermolekularem Heparin (NMH) einer Sekundärprophylaxe mit Vitamin-K-Antagonisten überlegen ist. Welche Krebspatienten am ehesten von einer primären Thromboseprophylaxe mit NMH profitieren, ist dagegen nicht abschließend geklärt. Diesbezüglich muss das individuelle Risikoprofil, das in erheblichem Maße durch den Allgemeinzustand des Patienten und etwaige Begleiterkrankungen mitbestimmt wird, berücksichtigt werden. Experimentelle und klinische Studien legen nahe, dass NMH über eine multifaktorielle Beeinflussung der Tumorbiologie auch in der Krebstherapie von Nutzen sein könnte.AbstractCancer patients are at increased risk of thromboembolic complications, which are commonly referred to as Trousseau’s syndrome. Besides the potentially dramatic effects of the tumor on the coagulation and fibrinolytic systems, various supportive measures and more specific cancer treatments, such as surgery or chemotherapy contribute to the pathophysiology of cancer-associated venous thromboembolism (VTE). Clinical trials have shown that long-term therapy with low-molecular-weight heparin (LMWH) is superior to secondary prophylaxis with vitamin K antagonists in the treatment of patients with cancer-associated VTE. Based on currently available clinical evidence it is not clear which cancer patient should be offered primary thromboprophylaxis with LMWH. In this respect, the individual risk profile which is substantially influenced by the general condition of the patient and possible co-morbidities have to be taken into account. Recent experimental and clinical studies have suggested that LMWH affects tumor biology at various levels and may thus be potentially beneficial as an adjunct in cancer therapy.