Anti-thrombotics in thrombosis and cancer

ArticleinFuture Oncology 1(3):395-403 · July 2005with4 Reads
DOI: 10.1517/14796694.1.3.395 · Source: PubMed
  • 49.37 · Albany College of Pharmacy and Health Sciences
Abstract
Many cancer patients have a reportedly hypercoagulable state, with recurrent thrombosis due to the impact of cancer cells and chemotherapy or radiotherapy on the coagulation cascade. Studies have demonstrated that unfractionated heparin or its low-molecular-weight fractions interfere with various processes involved in tumor growth and metastasis. These include fibrin formation; binding of heparin to angiogenic growth factors, such as basic fibroblast growth factor and vascular endothelial growth factor; modulation of tissue factor; and perhaps other more important modulatory mechanisms, such as enhanced tissue factor pathway inhibitor (TFPI) release and inhibition of various matrix-degrading enzymes. Clinical trials have suggested a clinically relevant effect of low-molecular-weight heparin (LMWH), as compared with unfractionated heparin, on the survival of cancer patients with deep vein thrombosis. Similarly, the impact of warfarin on the survival of cancer patients with thromboembolic disorders was demonstrated. Studies from the author's laboratory demonstrated a significant role for LMWH, warfarin, anti-VIIa, and LMWH-releasable TFPI on the regulation of angiogenesis, tumor growth and tumor metastasis. Thus, modulation of tissue factor/VIIa noncoagulant activities by LMWH, warfarin, anti-VIIa, or TFPI may be a useful therapeutic method for the inhibition of angiogenesis associated with human tumor growth and metastasis. Additionally, antiplatelet drugs may have an impact on tumor metastasis, and the combination of antiplatelets and anticoagulants at adjusted doses may provide greater benefits to cancer patients.
    • "Acute arterial thrombotic events were also reported to be induced by cytotoxic chemotherapy especially in patients receiving platinum-based chemo- therapy [38, 39]. The impact of cancer cells and chemotherapy on the activation of the coagulation cascade is responsible for a prothrombotic state found in many cancer patients [40] . Various mechanisms related to the activation of the coagulation or fibrinolytic systems in cancer may be involved in tumor development, progression and metastasis. "
    [Show abstract] [Hide abstract] ABSTRACT: Enhancing chemotherapy delivery to tumors, improving tumor growth control, reducing metastasis, and increasing survival are all critical objectives of improved cancer therapy. One of the obstacles to the success of anticancer therapies is related to the inefficient distribution of drugs to tumor cells. To be effective, chemotherapeutics must reach a concentration in cancer cells that is sufficient to inhibit its targets. In the past years, the vascular normalization theory has gained widespread acceptance for explaining additional antitumor effects of inhibitors of vascular endothelial growth factor (VEGF) signaling, when combined with chemotherapeutics. Vascular normalization is a strategy to enhance the antitumor effects of chemotherapeutics, but this is time and dose dependent and therefore difficult to implement clinically. Thus, alternative strategies that overcome these issues are needed. Accumulating scientific data demonstrate an alternative approach called "vascular promotion therapy" can increase chemotherapeutics delivery and intracellular uptake of the drug and reduces hypoxia by increasing tumor blood vessel density, blood flow, leakiness, and dilation, which leads to reduced cancer growth and metastasis. In this article, we first summarize the structural and functional abnormalities of the tumor microvasculature to highlight the importance of this phenomenon for chemotherapeutics distribution. Next, we summarize the limitations of anti-angiogenic strategy in cancer treatment, discuss some key prototypical underlying mechanisms of vascular normalization and initial clinical evidence of vascular promotion therapy, and speculate on the clinical potential of anticoagulation as a novel paradigm to improve cancer treatment.
    Full-text · Article · Aug 2015
    • "On the contrary, fondaparinux did not significantly affect HUVEC tubule formation. Such results, which are consistent with the majority of previous studies both on Matrigel [41,48495051, and in in vivo models [52], have been strongly strengthened by our in vivo experimental model, which could demonstrate that the VEGF-promoted angiogenesis in Matrigel sponges is significantly reduced by bemiparin, while it is not influenced by fondaparinux. On the other hand, very few studies reported opposite results on angiogenesis regulation, where an increase in tube formation on Matrigel was reported when HUVEC were co-treated with fibroblast growth factor 2 (FGF-2) and LMWH [53] . "
    [Show abstract] [Hide abstract] ABSTRACT: Conventional therapy for venous thromboembolism or acute coronary syndrome involves the administration of glycoanticoagulants (heparins) or oligosaccharides (fondaparinux). We evaluated the effects of such drugs on angiogenesis and vasculogenesis-like models. Human umbilical vein endothelial cells or human endothelial progenitor cells were treated with bemiparin, fondaparinux or unfractionated heparin, at concentrations reflecting the doses used in clinical practice. After 24h, cell viability, proliferation, tubule formation and angiogenic molecular mechanisms, such as activation of the serine/threonine kinase AKT, were assessed. In vivo angiogenesis was studied using a Matrigel sponge assay in mice. Bemiparin gave a significant decrease of in vitro angiogenesis as shown by the reduction of endothelial cell tubule network, while both fondaparinux and unfractionated heparin did not show any significant effect. In assays of Matrigel sponge invasion in mice, unfractionated heparin was able to stimulate angiogenesis and, conversely, bemiparin inhibited angiogenesis. Furthermore, both bemiparin and fondaparinux caused a significant reduction in an in vitro vasculogenesis-like model, as demonstrated by the decrease of tubule network after co-seeding of endothelial progenitor cells and human umbilical vein endothelial cells. In addition, unfractionated heparin but not bemiparin was able to increase AKT phosphorylation. In in vitro experiments, bemiparin was the only drug to show an anti-angiogenic and vasculogenic-like effect, unfractionated heparin showed only a trend to increase in angiogenesis assay and fondaparinux affected only the vasculogenesis-like model. Notably, the in vivo experiments corroborated these data. Such results are important for the choice of a patient-tailored therapy.
    Full-text · Article · Apr 2012
  • [Show abstract] [Hide abstract] ABSTRACT: Low-molecular-weight heparins (LMWH) exhibit potent anticoagulant efficacy via their plasmatic effects on thrombin and factor Xa. These agents are also effective in releasing endothelial tissue factor pathway inhibitor (TFPI), the natural inhibitor of tissue factor, and exhibit significant anti-metastatic effects in experimental animal models. However, the potential for bleeding complications has slowed down the more widespread adoption of LMWH therapy in cancer patients. In this study, the effect of a non-anticoagulant form of LMWH (NA-LMWH) on experimental lung metastasis and tumor cell-induced platelet aggregation in vivo was compared to the LMWH enoxaparin. Using the B16 melanoma mouse model of metastasis, subcutaneous (s.c.) injection of NA-LMWH or enoxaparin (10 mg/kg), three hours before intravenous (i.v.) injection of metastatic melanoma cells, followed by daily doses for 14 days, reduced lung tumor formation by 70% (P < 0.001). I.v. injection of tumor cells resulted in a significant (50-62%, P < 0.01) fall in platelet counts. Pre-injection (i.v.) of enoxaparin completely abolished the tumor cell-induced thrombocytopenia, whereas NA-LMWH had no effect. Four hours after a single s.c. dose, enoxaparin but not NA-LMWH prolonged the clotting time three-fold and delayed the time to clot initiation more than 10-fold as measured by a Sonoclot analyzer and by thromboelastography, respectively. Enoxaparin but not NA-LMWH demonstrated a significant anticoagulant effect in mice. Both NA-LMWH and enoxaparin caused similar TFPI release from endothelial cells in vitro. These data provide evidence to support the potential of NA-LMWH as an anti-metastatic agent without any significant impact on coagulation.
    Article · Dec 2006
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