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Purpose: We sought to determine whether venous thromboembolism in cancer patients is associated with aberrant plasma levels of hemostatic and angiogenic factors. Patients and Methods: Peripheral blood was collected before anticoagulant therapy from cancer patients with acute deep venous thrombosis (DVT; DVT + cancer group, n = 32), those without DVT (cancer control group, n = 36), and patients with acute DVT but no cancer (DVT control group, n = 58). Plasma assays of activation and inhibition of coagulation and fibrinolysis, as well as angiogenesis activation, were then performed. Results: Median levels of thrombin-antithrombin complex, prothrombin fragments 1 + 2, and von Willebrand factor antigen were significantly greater in the DVT + cancer group than in the cancer control and DVT control groups (17.8 ng/mL v 4.6 ng/mL and 9.8 ng/mL, P = .0001 and P = .003, respectively; 3.65 nmol/L v 1.60 nmol/L and 2.71 nmol/L, P < .0001 and P = .011, respectively; and 4.04 U/mL v 2.26 U/mL and 2.06 U/mL, P < .0001, respectively). Median levels of tissue-type plasminogen activator were also significantly higher, while protein C activity was lower in the DVT + cancer group than in the DVT control group (14.6 ng/mL v 9.50 ng/mL, respectively, P = .0005; 0.89 U/mL v 1.11 U/mL, respectively, P = .0008). Conclusion: These data not only support prior observations of coagulation activation in patients with malignancy, but also provide new evidence for enhanced coagulation activation in the setting of acute venous thromboembolism in cancer. Future prospective studies are warranted to determine whether these and other potential markers of hypercoagulability may help to identify cancer patients at highest risk for venous thromboembolism.

e20514 Background: Cancer patients receiving chemotherapy, biologic, and molecular targeted therapies are at increased risk of venous thromboembolism (VTE). Currently available anticoagulants (ACs) are not well suited to prevent VTE in such patients. Vitamin K antagonist oral ACs require frequent lab monitoring and low molecular weight heparins require daily subcutaneous injection. There is concern for bleeding with ACs. Apixaban (A) is a new antithrombotic agent which inhibits activated coagulation Factor X, is taken orally, and does not require lab monitoring. Trials to prevent post-operative VTE in orthopedic surgery showed that A was effective and safe. We wanted to assess the feasibility of A in cancer. Methods: In a randomized phase II trial, patients with metastatic cancer on 1st or 2nd line chemotherapy received study drug once daily for 12 weeks; either 5, 10 or 20 mg of A, or placebo. The primary outcome measure was the proportion of patients remaining free of major bleeding (MB), clinically relevant non-major bleeding (CRNMB), VTE, and grade ≥3 adverse events considered to be probably/definitely related to study drug (AE*). After 125 patients were recruited, the sponsor eliminated further randomization to the 10 and 20 mg arms, to add experience with the 5 mg dose currently under evaluation for VTE prevention in other conditions. Data on the first 125 patients are reported. Results: The study population was 50% male; 88% had ECOG performance status 0 or 1. The most common cancers were breast, colon, pancreas, and myeloma. 23% had liver metastases. Approximately 80% of A patients completed 12 weeks of treatment. The numbers of patients with events were: Conclusions: Apixiban was well tolerated in patients with advanced cancer on chemotherapy. Major bleeding, thrombosis, and drug-related SAEs were very low. These results support further study of A in phase III trials for VTE prevention in cancer patients. [Table: see text] [Table: see text]