Coagulation activation anc microparticle-associated coagulant activity in cancer patients An exploratory prospective study

Cancer increases the risk of venous thromboembolism (VTE). Here, we investigated the contribution of microparticle (MP)-dependent procoagulant activity to the prothrombotic state in these patients. In 43 cancer patients without VIE at study entry and 22 healthy volunteers, markers of in vivo and MP-dependent coagulation were measured and patients were prospectively followed for six months for the development of VTE. Procoagulant activity of MPs was measured in vitro using a tissue factor (TF)-independent phospholipid dependent test, a factor Xa-generation assay with and without anti-IF, and a fibrin generation test (FGT) with and without anti-factor VII(a). Markers of in vivo coagulation activation and total number of MPs at baseline were significantly elevated in cancer patients compared to controls (F1+2 246 vs. 156 pM, thrombin-antithrombin complexes 4.1 vs. 3.0 mg/l, D-dimer 0.76 vs. 0.22 mg/l and 5.53 x 106 vs. 3.37 x 106 MPs/ml). Five patients (11.6%) developed VTE. Patients with VTE had comparable levels of coagulation activation markers and phospholipid-dependent MP procoagulant activity. However, median IF-mediated Xa-generation (0.82 vs. 0.21 pg/ml, p=0.016) and median Vila-dependent FGT (13% vs. 0%, p=0.036) were higher in the VIE group compared with the non-VTE group. In this exploratory study the overall hypercoagulable state in cancer patients was not associated directly with the MP phospholipiddependent procoagulant activity. However, in the patients who developed VTE within six months when compared to those who did not, an increased MP procoagulant activity was present already at baseline, suggesting this activity can be used to predict VIE