Heparin In Cancer Research Articles

Effect of Sulfated NON-Anticoagulant Low Molecular Weight Heparin in Cancer and NON-Cancer Associated Thrombosis

Introduction: The process of thrombosis depends on a complex interaction between different factors including vascular endothelial activation, platelet activation and adhesion. Blood coagulation process initiated by plasma protease factor VIIa in complex with the membrane protein tissue factor. Cancer-associated thrombosis (CAT) accounts for about 20% of all cases of Venous Thromboembolism (VTE). Tissue factor (TF) is documented to be highly expressed on the cancer cells and pathological angiogenic endothelial cells. Subsequent theories proposed that the cancer cells activate the coagulation cascade, as the oncogenes cause tumor transformation, which in turn causes the cancer tissues to be able to express different pro-coagulant proteins. VTE risk factors can be divided into cancer- and therapy-associated factors. Low molecular weight heparin (LMWH) is used for prophylaxis and treatment of deep vein thrombosis and CAT as it significantly shortened both duration of thromboembolic crisis and hospitalization. Safety concerns associated with the bleeding risks are the major barrier to dose optimization of treatments. Here, we used the novel sulfated non-anticoagulant LMWH, referred to as S-NACH, which has a similar activity of LMWH but devoid of systemic anti-factor Xa and IIa activity. The sulfated form has enhanced S-NACH binding to the vascular endothelial cells, release TFPI and potentiate the action of tissue factor pathway inhibitors (TFPI). We investigated the effects of S-NACH on clot kinetics in comparison with LMWH using thrombelstography (TEG) and examined its in vitro and in vivo effects on vascular endothelial release capacity of TFPI. Also we investigate the effects of S-NACH on cancer-associated thrombosis-mediated by human pancreatic cancer cells (SUIT2). Methods: We conducted both in vitro and in vivo experiments using our compound (S-NACH) to test its efficacy on coagulation properties in comparison to LMWH (enoxaparin). We compared the effects on the coagulation time, time to clot initiation and thrombus strength level in vitro, with and without HUVEC endothelial cell line coated into cups used for the TEG analysis. TFPI levels were also estimated in both in vitro and in vivo models at different doses of S-NACH. In addition, the effect of S-NACH on factors Xa and IIa was assessed in mice and rabbits. Also, weused pancreatic cancer cell line (SUIT2) to test the efficiency of blood coagulation in the presence of S-NACH, and Enoxaparin at 1-10 μg. Results: TEG assay have shown that, increasing concentrations of S-NACH (0.1 - 10 ug) did not affect the clotting time (R) and maximum amplitude of the clot formation (MA), while LMWH (enoxaparin) was associated with marked increased clotting time (R) and decreased maximum amplitude of the clot formation (MA) in comparison to control. Using HUVEC cell line coated cups; both S-NACH and LMWH were associated with increased clotting time (R) and decreased maximum amplitude of the clot formation (MA). This is due to the ability of HUVEC cell to release of TFPI. In the in vivo study, administration of enoxaparin inhibited both factors Xa and IIa, while administration of S-NACH did not affect the activities of these coagulation factors. S-NACH caused 3 folds greater tissue factor pathway inhibitor (TFPI) release from human endothelial cells and in mice versus enoxaparin. On the other hand, TEG assay shows significantly decreased clotting time (R-value) and increased clot strength in blood from healthy donors when adding pancreatic SUIT2 cells. Data from the TEG assay demonstrated lack of effects of S-NACH or TFPI alone on clot kinetics in human. In contrast, S-NACH (1-10 μg) in the presence of 0.01-0.1 ng TFPI resulted in a dose-dependent suppression of clot strength and prolongation of clotting time (Figure 1). Conclusion: S-NACH is devoid of anti-thrombin binding and inhibition of systemic anti-thrombin-dependent coagulation factors such as factor Xa and factor IIa but has an optimal releasing capacity of vascular endothelial TFPI that is associated with antithrombotic activities without any effect on hemostasis. Also, S-NACH prevents CAT without any effects on hemostasis. Disclosures No relevant conflicts of interest to declare.

The use of prophylactic heparin in cancer

The use of prophylactic heparin in cancer

Determining the anti-coagulant-independent anti-cancer effects of heparin

Sir, We enjoyed the recent articles on cancer-associated thrombosis and wish to comment on the attempts to explain the beneficial effects of heparin in cancer (Noble and Pasi, 2010; Kakkar and Macbeth, 2010). Cited evidence indicates that the survival benefit of heparin in cancer is unexplained by venous thromboembolism (VTE) prophylaxis alone; unlike warfarin, heparin improves survival in cancer patients without VTE (Zielinski and Hejna, 2000; Cunningham et al, 2009). Alternative explanations independent of VTE prophylaxis include regulation of tissue factor and FVIIa with the TF–VIIa complex (Boccaccio and Comoglio, 2005; Rickles and Falanga, 2009), inhibition of cancer micrometastasis by blocking platelet and cancer cell aggregation (Borsig et al, 2001), and disruption of host wound-healing responses (including clotting and fibrin deposition) proposed to facilitate construction of tumour microenvironment (Dvorak, 1986). Although these explanations do not require VTE prophylaxis, they still relate to heparin's clotting-related effects. Heparin is a multifunctional, highly sulphated form of heparan sulphate (HS), a member of the glycosaminoglycan family. Given the vast interactome of HS and related heparins (Ori et al, 2008), it is unsurprising that heparin's benefit in cancer cannot be linked solely to its anti-coagulant activity (Fuster and Esko, 2005; Escobar Galvis et al, 2007). Estimated to carry far more information than nucleic acids, the HS family are ubiquitous, varied and highly complex regulators of normal organogenesis (e.g., through growth factor modulation) with pleiotropic biological effects unrelated to anti-coagulation (Bishop and Schuksz Esko, 2007). Likewise, heparin has diverse, structure-related biological properties, only one of which is anti-coagulation and this can be manipulated through judicious structural modification to generate low-molecular-weight derivatives with improved selectivity (Norrby, 1993). Clinicians glimpsed heparin's diversity during replacement of unfractionated heparins with fractionated low-molecular-weight alternatives (although the focus remained anti-coagulation). If they are entirely anti-coagulant related, further exploitation of heparin's benefits in cancer is inevitably limited by haemorrhage risk. However, by separating anti-coagulant from other bioactivities, ‘engineered' (selectively modified) heparins provide the means to test whether heparins mediate their benefits in cancer independently of coagulation effects, as has been achieved for other biological activities such as inhibition of β-secretase or blood cell rosetting in malaria (Patey et al, 2006; Yates et al, 1996; Skidmore et al, 2008). Such developments offer the prospect of screening and developing a broad new class of anti-cancer heparins that can be used at optimum anti-tumour levels while retaining ameliorated anti-thrombotic activity.

Selectins, Heparins, and Cancer: Rationale for Clinical Trials.

Abstract Heparin has been in use as an anticoagulant for many decades, based on its ability to enhance antithrombin activity. However, heparin is a natural product, comprising a complex polydisperse mixture of highly sulfated glycosaminoglycan chains, only a fraction of which bind antithrombin. We reported that heparin has an unrelated biological effect in inhibiting P- and L-selectin binding to their natural ligands. Meanwhile, animal studies and analyses of human clinical data suggest that heparin therapy increases survival in various cancers. In contrast, clinical trials using Vitamin K antagonists showed no major effect on survival in most studies. Thus, the heparin effect on cancer may not be due primarily to its anticoagulant function, but rather to inhibition of P- and L-selectin. Indeed, we have demonstrated that the selectins play critical roles in animal models of the hematogeneous phase of carcinoma metastasis and of the platelet-rich microthromboses typical of classical Trousseau’s syndrome. This involves interactions of selectins with pathological ligands produced by carcinoma cells, particularly sialylated, fucosylated, and sulfated mucins. The critical selectin-mediated interactions blocked by heparin occur early in the metastatic cascade. Also, inhibition occurs at concentrations in the clinically acceptable range. Furthermore, there are many other salutary actions of heparin in cancer, including adsorption of cytokines and growth factors, inhibition of thrombin generation, and inhibition of heparanases. We, therefore, suggest that heparin therapy for metastasis prevention in humans be revisited, with these new paradigms in mind. Most of the above studies used unfractionated heparin. We found that selectin-inhibiting effects of low molecular weight heparins (LMWH) are varied and that the synthetic heparinoid pentasaccharide that specifically binds antithrombin does not block at clinically relevant levels. Optimal dosing to sustain clinically acceptable levels of all these drugs in mice gave congruent results. These data suggest a rational clinical trial comparing an optimal LMWH with the pentasaccharide in the pre-/peri- and immediate post-operative periods of newly diagnosed carcinomas. Notably, heparin can also attenuate inflammatory pathologies in animal models by blocking L- and P-selectin.

Low-Molecular-Weight Heparin in Thrombosis and Cancer

Venous thromboembolism (VTE) is a recognized complication of malignant disease and multiple risk factors contribute to the hypercoagulability that commonly accompanies malignancy. Thromboprophylaxis with antithrombotic drugs such as the low-molecular-weight heparins (LMWHs) can be used to control the hypercoagulable state and to reduce the incidence of VTE in patients with cancer. Clinical and biochemical data suggest that LMWHs may also inhibit tumor growth, leading to a survival benefit in these patients. Many cancer patients reportedly have a hypercoaguable 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 (UFH) or its low-molecular-weight fractions interfere with various processes involved in tumor growth and metastasis. Clinical trials in cancer patients with thromboembolic disorders have suggested a clinically relevant effect of LMWHs (as compared with UFH) 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 in certain tumor types. Studies from our laboratory demonstrated a significant role for LMWH, warfarin, anti-VIIa, and LMWH releasable tissue factor pathway inhibitor on the regulation of angiogenesis, tumor growth, and tumor metastasis. However, a direct anticancer effect for heparin in cancer patients without thrombosis still remains to be clinically documented.

Rationale for heparin treatment of colon cancer

SummaryIt is widely known that the systemic blood coagulation mechanism is often activated in malignancy, leading to an increased incidence of vascular thromboses in patients with cancer. It is not widely appreciated, however, that products of the coagulation mechanism may also support tumor growth and dissemination. Interest in this approach to cancer therapy has surged recently because of mounting evidence that the familiar anticoagulant drug, heparin, may impede tumor progression. Heparin has the capacity to modify angiogenesis, growth factor and protease activity, immune function, cell proliferation and gene expression in ways that may block malignant dissemination. Clinical trials in which heparin has been administered to a broad spectrum of patients to prevent or treat thrombosis have unexpectedly shown improvement in survival in the subset of patients with malignancy entered to these studies. Meta-analyses of clinical trials comparing unfractionated (UF) versus low molecular weight (LMW) heparin treating venous thromboembolism suggest that there may be substantial improvement in cancer outcome in patients with malignancy randomized to receive LMW heparin. These findings provide a rationale for definitive clinical trials of LMW heparin in cancer, and the results of several such studies that are currently underway are awaited with interest.