The coagulation system as a target for the treatment of human gliomas

Risk factors for postoperative thrombosis-related complications in patients undergoing malignant brain tumor resection: a retrospective cohort study

Introduction

Patients with malignant brain tumors frequently exhibit hypercoagulation and are at a high risk of postoperative thrombosis-related complications. However, the risk factors for postoperative thrombosis-related complications remain unclear.

Methods

In this retrospective, observational study, we consecutively enrolled elective patients undergoing resection of malignant brain tumors from 26 November 2018 to 30 September 2021. The primary objective of the study was to identify risk factors for a composite of three major adverse events including postoperative lower limb deep venous thrombosis, pulmonary embolism, and cerebral ischemia.

Results

A total of 456 patients were enrolled in this study, where 112 (24.6%) patients had postoperative thrombosis-related complications, 84 (18.4%) with lower limb deep venous thrombosis, 0 (0.0%) with pulmonary embolism, and 42 (9.2%) with cerebral ischemia. In a multivariate model, age more than 60 years (OR: 3.98, 95% CI: 2.30-6.88, P < 0.001), preoperative abnormal APTT (OR: 2.81, 95% CI: 1.06-7.42, P = 0.037), operation duration longer than 5 h (OR: 2.36, 95% CI: 1.34-4.16, P = 0.003), and admission to ICU (OR: 2.49, 95% CI: 1.21-5.12, P = 0.013) were independent risk factors of the postoperative deep vein thrombosis. Intraoperative plasma transfusion (OR: 6.85, 95% CI: 2.73-17.18, P < 0.001) was associated with significantly increased odds of deep vein thrombosis.

Conclusion

Patients with craniocerebral malignant tumors have a high incidence of postoperative thrombosis-related complications. There is an increase in the odds of postoperative lower limb deep venous thrombosis in patients; over 60 years old, with preoperative abnormal APTT, undergoing surgeries longer than 5-h, admission to ICU, or receiving intraoperative plasma infusion. Fresh frozen plasma infusion should be used more cautiously, especially in patients with a high risk of thrombosis.

Growth differentiation factor-15 overexpression promotes cell proliferation and predicts poor prognosis in cerebral lower-grade gliomas correlated with hypoxia and glycolysis signature

AIMS

Growth differentiation factor-15 (GDF15) plays complex and controversial roles in cancer. In this study, the prognostic value and the exact biological function of GDF15 in cerebral lower-grade gliomas (LGGs) and its potential molecular targets were examined.

MAIN METHODS

Wilcoxon signed-rank test and logistic regression were applied to analyze associations between GDF15 expression and clinical characteristics using the Cancer Genome Atlas (TCGA) database. Overall survival was analyzed using Kaplan-Meier and Cox analyses. Gene set enrichment analysis (GSEA) and the hypoxia risk model was conducted to identify the potential molecular mechanisms underlying the effects of GDF15 on LGGs tumorigenesis. The biological function of GDF15 was examined using gain- and loss-of-function experiments, and a recombinant hGDF15 protein in LGG SW1783 cells in vitro.

KEY FINDINGS

We found that higher GDF15 expression is associated with poor clinical features in LGG patients, and an independent risk factor for overall survival among LGG patients. GSEA results showed that the poor prognostic role of GDF15 in LGGs is related to hypoxia and glycolysis signatures, which was further validated using the hypoxia risk model. Furthermore, GDF15 overexpression facilitated cell proliferation, while GDF15 siRNA inhibits cell proliferation in LGG SW1783 cells. In addition, GDF15 was upregulated upon CoCl2 treatment which induces hypoxia, correlating with the upregulation of the expressions of HIF-1α and glycolysis-related key genes in SW1783 cells.

SIGNIFICANCE

GDF15 may promote LGG tumorigenesis that is associated with the hypoxia and glycolysis pathways, and thus could serve as a promising molecular target for LGG prevention and therapy.

Systemic coagulation is activated in patients with meningioma and glioblastoma

PURPOSE

Up to 30% of patients with glioblastoma (GBM) develop venous thromboembolism (VTE) over the course of the disease. Although not as high, the risk for VTE is also increased in patients with meningioma. Direct measurement of peak thrombin generation (TG) allows quantitative assessment of systemic coagulation activation in patients with GBM and meningioma. Our aim was to determine the extent of systemic coagulation activation induced by brain tumors, to measure the shift between pre- and post-operative peak TG in patients with GBM, and to assess the relationship between pre-surgical peak TG and pre-operative brain tumor volume on imaging.

METHODS

Pre- and post-surgical plasma samples were obtained from successive patients with GBM and once from patients with meningioma and healthy age- and sex-matched blood donor controls. TG was measured using the calibrated automated thrombogram (CAT) assay, and tumor volumes were measured in pre-surgical MRI scans.

RESULTS

Pre-surgical peak TG was higher in patients with GBM than in controls (288.6 ± 54.1 nM vs 187.1 ± 41.7 nM, respectively, P < 0.001), and, in the nine patients with GBM and paired data available, peak TG was significantly reduced after surgery (323 ± 38 nM vs 265 ± 52 nM, respectively, P = 0.007). Similarly, subjects with meningioma demonstrated higher peak TG compared to controls (242.2 ± 54.9 nM vs 177.7 ± 57.0 nM, respectively, P < 0.001). There was no association between peak TG and pre-operative tumor volume or overall survival.

CONCLUSION

Our results indicate that systemic coagulation activation occurs with both meningioma and GBM, but to a greater degree in the latter. Preoperative peak TG did not correlate with tumor volume, but removal of GBM caused a significant decrease in coagulation activation.

Imbalance in Coagulation/Fibrinolysis Inhibitors Resulting in Extravascular Thrombin Generation in Gliomas of Varying Levels of Malignancy

Neoplastic processes are integrally related to disturbances in the mechanisms regulating hemostatic processes. Brain tumors, including gliomas, are neoplasms associated with a significantly increased risk of thromboembolic complications, affecting 20-30% of patients. As gliomas proliferate, they cause damage to the brain tissue and vascular structures, which leads to the release of procoagulant factors into the systemic circulation, and hence systemic activation of the blood coagulation system. Hypercoagulability in cancer patients may be, at least in part, a result of the inadequate activity of coagulation inhibitors. The aim of the study was to evaluate the expression of the inhibitors of the coagulation and fibrinolysis systems (tissue factor pathway inhibitor, TFPI; tissue factor pathway inhibitor-2 TFPI-2; protein C, PC; protein S, PS, thrombomodulin, TM; plasminogen activators inhibitor, PAI-1) in gliomas of varying degrees of malignancy. Immunohistochemical studies were performed on 40 gliomas, namely on 13 lower-grade (G2) gliomas (8 astrocytomas, 5 oligodendrogliomas) and 27 high-grade gliomas (G3-12 anaplastic astrocytomas, 4 anaplastic oligodendrogliomas; G4-11 glioblastomas). A strong expression of TFPI-2, PS, TM, PAI-1 was observed in lower-grade gliomas, while an intensive color immunohistochemical (IHC) reaction for the presence of TFPI antigens was detected in higher-grade gliomas. The presence of PC antigens was found in all gliomas. Prothrombin fragment 1+2 was observed in lower- and higher-grade gliomas reflecting local activation of blood coagulation. Differences in the expression of coagulation/fibrinolysis inhibitors in the tissues of gliomas with varying degrees of malignancy may be indicative of their altered role in gliomas, going beyond that of their functions in the hemostatic system.

Heterogeneous Expression of Proangiogenic and Coagulation Proteins in Gliomas of Different Histopathological Grade

Brain gliomas are characterized by remarkably intense invasive growth and the ability to create new blood vessels. Angiogenesis is a key process in the progression of these tumors. Coagulation and fibrinolysis factors play a role in promoting angiogenesis. The aim of the study was to evaluate the expression of proangiogenic proteins (VEGF and bFGF) and hemostatic proteins (TF, fibrinogen, fibrin, D-dimers) associated with neoplastic cells and vascular endothelial cells in brain gliomas of various degrees of malignancy. Immunohistochemical tests were performed using the ABC method with the use of mono- and polyclonal antibodies. The obtained results indicated that both neoplastic cells and vascular endothelial cells in gliomas of various degrees of malignancy are characterized by heterogeneous expression of proteins of the hemostatic system and angiogenesis markers. The strongest expression of proangiogenic factors and procoagulant factors was demonstrated in gliomas of higher-grade malignancy.

Role of Protease-Activated Receptor-1 in Glioma Growth

Activation of a thrombin receptor, protease-activated receptor-1 (PAR-1), induces angiogenesis, cell proliferation, and invasion in tumors. The present study examined the effect of host PAR-1 gene deletion on glioma growth in a mouse model. F98 glioma cells were implanted into the right caudate of either wild type (WT) or PAR-1 knockout (KO) mice. Mice underwent magnetic resonance imaging (MRI) and the brains were used for measurements of brain water content and tumor mass. Levels of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) were also measured by ELISA (enzyme-linked immunosorbent assay). We found brain water content in the ipsilateral hemisphere and the tumor mass were significantly lower in PAR-1 KO than WT mice at day 12 after implantation of F98 cells (p < 0.05). HIF-1α protein levels in the ipsilateral hemisphere were higher in the WT mice (373 ± 25 pg/g brain tissue vs 333 ± 35 pg/g brain tissue in PAR-1 KO mice, p < 0.05) 7 days after F98 cell implantation. VEGF protein levels were also higher in the ipsilateral hemisphere of WT mice (219 ± 21 vs 166 ± 22 pg/g brain tissue in PAR-1 KO mice, p < 0.01). In conclusion, PAR-1 has a role in glioma growth and could be a new therapeutic target for gliomas.

CUSP9* treatment protocol for recurrent glioblastoma: aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, ritonavir, sertraline augmenting continuous low dose temozolomide

CUSP9 treatment protocol for recurrent glioblastoma was published one year ago. We now present a slight modification, designated CUSP9*. CUSP9* drugs--aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, sertraline, ritonavir, are all widely approved by regulatory authorities, marketed for non-cancer indications. Each drug inhibits one or more important growth-enhancing pathways used by glioblastoma. By blocking survival paths, the aim is to render temozolomide, the current standard cytotoxic drug used in primary glioblastoma treatment, more effective. Although esthetically unpleasing to use so many drugs at once, the closely similar drugs of the original CUSP9 used together have been well-tolerated when given on a compassionate-use basis in the cases that have come to our attention so far. We expect similarly good tolerability for CUSP9*. The combined action of this suite of drugs blocks signaling at, or the activity of, AKT phosphorylation, aldehyde dehydrogenase, angiotensin converting enzyme, carbonic anhydrase -2,- 9, -12, cyclooxygenase-1 and -2, cathepsin B, Hedgehog, interleukin-6, 5-lipoxygenase, matrix metalloproteinase -2 and -9, mammalian target of rapamycin, neurokinin-1, p-gp efflux pump, thioredoxin reductase, tissue factor, 20 kDa translationally controlled tumor protein, and vascular endothelial growth factor. We believe that given the current prognosis after a glioblastoma has recurred, a trial of CUSP9* is warranted.

Comprehensive characterization of glioblastoma tumor tissues for biomarker identification using mass spectrometry-based label-free quantitative proteomics

Cancer is a complex disease; glioblastoma (GBM) is no exception. Short survival, poor prognosis, and very limited treatment options make it imperative to unravel the disease pathophysiology. The critically important identification of proteins that mediate various cellular events during disease is made possible with advancements in mass spectrometry (MS)-based proteomics. The objective of our study is to identify and characterize proteins that are differentially expressed in GBM to better understand their interactions and functions that lead to the disease condition. Further identification of upstream regulators will provide new potential therapeutic targets. We analyzed GBM tumors by SDS-PAGE fractionation with internal DNA markers followed by liquid chromatography-tandem mass spectrometry (MS). Brain tissue specimens obtained for clinical purposes during epilepsy surgeries were used as controls, and the quantification of MS data was performed by label-free spectral counting. The differentially expressed proteins were further characterized by Ingenuity Pathway Analysis (IPA) to identify protein interactions, functions, and upstream regulators. Our study identified several important proteins that are involved in GBM progression. The IPA revealed glioma activation with z score 2.236 during unbiased core analysis. Upstream regulators STAT3 and SP1 were activated and CTNNα was inhibited. We verified overexpression of several proteins by immunoblot to complement the MS data. This work represents an important step towards the identification of GBM biomarkers, which could open avenues to identify therapeutic targets for better treatment of GBM patients. The workflow developed represents a powerful and efficient method to identify biomarkers in GBM.

Expression of tissue factor signaling pathway elements correlates with the production of vascular endothelial growth factor and interleukin-8 in human astrocytoma patients

The expression levels of tissue factor (TF), the clotting initiator protein, have been correlated with angiogenesis and the histological grade of malignancy in glioma patients. The pro-tumor function of TF is linked to a family of G protein-coupled receptors known as protease-activated receptors (PARs), which may be activated by blood coagulation proteases. Activation of PARs elicits a number of responses, including the expression of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). In the present study, we analyzed the expression of TF signaling pathway elements (TF, PAR1 and PAR2) and evaluated their correlation with the expression of downstream products (VEGF and IL-8) in human astrocytoma patients. Quantitative PCR (qPCR) showed a significant increase in TF expression in grade IV (glioblastoma) tumors, which was inversely correlated with the expression of the tumor-suppressor PTEN. Immunohistochemistry and qPCR analyses demonstrated a highly significant elevation in the expression of PAR1, but not PAR2, in tumor samples from high-grade astrocytoma patients. The elevated VEGF expression levels detected in the high-grade astrocytoma samples were positively correlated with TF, PAR1 and PAR2 expression. In addition, IL-8 was significantly increased in glioblastoma patients and positively correlated with TF and PAR2 expression. Further in vitro assays employing the human glioma cell lines U87-MG and HOG demonstrated that a synthetic peptide PAR2 agonist stimulated VEGF and IL-8 production. Our findings suggest a role for TF signaling pathway elements in astrocytoma progression, particularly in glioblastoma. Therefore, TF/PAR signaling elements may be suitable targets for the development of new therapies for the treatment of aggressive glioma.

Thrombin-cleaved fragments of osteopontin are overexpressed in malignant glial tumors and provide a molecular niche with survival advantage

Osteopontin (OPN), which is highly expressed in malignant glioblastoma (GBM), possesses inflammatory activity modulated by proteolytic cleavage by thrombin and plasma carboxypeptidase B2 (CPB2) at a highly conserved cleavage site. Full-length OPN (OPN-FL) was elevated in cerebrospinal fluid (CSF) samples from all cancer patients compared with noncancer patients. However, thrombin-cleaved OPN (OPN-R) and thrombin/CPB2-double-cleaved OPN (OPN-L) levels were markedly increased in GBM and non-GBM gliomas compared with systemic cancer and noncancer patients. Cleaved OPN constituted ∼23 and ∼31% of the total OPN in the GBM and non-GBM CSF samples, respectively. OPN-R was also elevated in GBM tissues. Thrombin-antithrombin levels were highly correlated with cleaved OPN, but not OPN-FL, suggesting that the cleaved OPN fragments resulted from increased thrombin and CPB2 in this extracellular compartment. Levels of VEGF and CCL4 were increased in CSF of GBM and correlated with the levels of cleaved OPN. GBM cell lines were more adherent to OPN-R and OPN-L than OPN-FL. Adhesion to OPN altered gene expression, in particular genes involved with cellular processes, cell cycle regulation, death, and inflammation. OPN and its cleaved forms promoted motility of U-87 MG cells and conferred resistance to apoptosis. Although functional mutation of the RGD motif in OPN largely abolished these functions, OPN(RAA)-R regained significant cell binding and signaling function, suggesting that the SVVYGLR motif in OPN-R may substitute for the RGD motif if the latter becomes inaccessible. OPN cleavage contributes to GBM development by allowing more cells to bind in niches where they acquire anti-apoptotic properties.

Ixolaris, a tissue factor inhibitor, blocks primary tumor growth and angiogenesis in a glioblastoma model

BACKGROUND

The expression levels of the clotting initiator protein Tissue Factor (TF) correlate with vessel density and the histological malignancy grade of glioma patients. Increased procoagulant tonus in high grade tumors (glioblastomas) also indicates a potential role for TF in progression of this disease, and suggests that anticoagulants could be used as adjuvants for its treatment.

OBJECTIVES

We hypothesized that blocking of TF activity with the tick anticoagulant Ixolaris might interfere with glioblastoma progression.

METHODS AND RESULTS

TF was identified in U87-MG cells by flow-cytometric and functional assays (extrinsic tenase). In addition, flow-cytometric analysis demonstrated the exposure of phosphatidylserine in the surface of U87-MG cells, which supported the assembly of intrinsic tenase (FIXa/FVIIIa/FX) and prothrombinase (FVa/FXa/prothrombin) complexes, accounting for the production of FXa and thrombin, respectively. Ixolaris effectively blocked the in vitro TF-dependent procoagulant activity of the U87-MG human glioblastoma cell line and attenuated multimolecular coagulation complexes assembly. Notably, Ixolaris inhibited the in vivo tumorigenic potential of U87-MG cells in nude mice, without observable bleeding. This inhibitory effect of Ixolaris on tumor growth was associated with downregulation of VEGF and reduced tumor vascularization.

CONCLUSION

Our results suggest that Ixolaris might be a promising agent for anti-tumor therapy in humans.

c-Met activation in medulloblastoma induces tissue factor expression and activity: effects on cell migration

Met, the receptor for hepatocyte growth factor (HGF), is a receptor tyrosine kinase that has recently emerged as an important contributor to human neoplasia. In physiological and pathological conditions, Met triggers various cellular functions related to cell proliferation, cell migration and the inhibition of apoptosis, and also regulates a genetic program leading to coagulation. Since medulloblastomas (MBs) express high levels of tissue factor (TF), the main initiator of blood coagulation, we therefore examined the link between Met and TF expression in these pediatric tumors. We observed that stimulation of the MB cell line DAOY with HGF led to a marked increase of TF expression and procoagulant activity, in agreement with analysis of clinical MB tumor specimens, in which tumors expressing high levels of Met also showed high levels of TF. The HGF-dependent increase in TF expression and activity required Src family kinases and led to the translocation of TF to actin-rich structures at the cell periphery, suggesting a role of the protein in cell migration. Accordingly, addition of physiological concentrations of the TF activator factor VIIa (FVII) to HGF-stimulated DAOY cells promoted a marked increase in the migratory potential of these cells. Overall, these results suggest that HGF-induced activation of the Met receptor results in TF expression by MB cells and that this event probably contribute to tumor proliferation by enabling the formation of a provisional fibrin matrix. In addition, TF-mediated non-hemostatic functions, such as migration toward FVIIa, may also play a central role in MB aggressiveness.

The role of tumor-and host-related tissue factor pools in oncogene-driven tumor progression

Oncogenic events play an important role in cancer-related coagulopathy (Trousseau syndrome), angiogenesis and disease progression. This can, in part, be attributed to the up-regulation of tissue factor (TF) and release of TF-containing microvesicles into the pericellular milieu and the circulation. In addition, certain types of host cells (stromal cells, inflammatory cells, activated endothelium) may also express TF. At present, the relative contribution of host- vs tumor-related TF to tumor progression is not known. Our recent studies have indicated that the role of TF in tumor formation is complex and context-dependent. Genetic or pharmacological disruption of TF expression/activity in cancer cells leads to tumor growth inhibition in immunodeficient mice. This occurred even in the case of xenotransplants of human cancer cells, in which TF overexpression is driven by potent oncogenes (K-ras or EGFR). Interestingly, the expression of TF in vivo is not uniform and appears to be influenced by many factors, including the level of oncogenic transformation, tumor microenvironment, adhesion and the coexpression of markers of cancer stem cells (CSCs). Thus, minimally transformed, but tumorigenic embryonic stem (ES) cells were able to form malignant and angiogenic outgrowths in the absence of TF. However, these tumors were growth inhibited in hosts (mice) with dramatically reduced TF expression (low-TF mice). Depletion of host TF also resulted in changes affecting vascular patterning of some, but not all types of tumors. These observations suggest that TF may play different roles growth and angiogenesis of different tumors. Moreover, both tumor cell and host cell compartments may, in some circumstances, contribute to the functional TF pool. We postulate that activation of the coagulation system and TF signaling, may deliver growth-promoting stimuli (e.g. fibrin, thrombin, platelets) to dormant cancer stem cells (CSCs). Functionally, these influences may be tantamount to formation of a provisional (TF-dependent) cancer stem cell niche. As such these changes may contribute to the involvement of CSCs in tumor growth, angiogenesis and metastasis.

On the molecular mechanisms for the highly procoagulant pattern of C6 glioma cells

BACKGROUND

That there is a correlation between cancer and procoagulant states is well-known. C6 glioma cell line was originally induced in random-bred Wistar-Furth rats and is morphologically similar to glioblastoma multiforme, the most common aggressive glioma resistant to therapeutic interventions.

OBJECTIVES

In this study we analyzed the molecular mechanisms responsible for the highly procoagulant properties of C6 glioma cells.

METHODS

The presence of tissue factor (TF) and phosphatidylserine (PS) in C6 cells was investigated by flow-cytometric and functional analyses. The assembly of extrinsic tenase, intrinsic tenase and prothrombinase complexes on these cells was studied using enzymatic assays employing plasma or purified proteins.

RESULTS

TF was identified by flow-cytometric and functional [factor (F) Xa formation in the presence of cells and FVIIa] assays. Alternatively, conversion of FX into FXa was also observed in the presence of C6 cells, FIXa and FVIIIa. This effect was both cell- and FVIIIa-dependent, being consistent with formation of the intrinsic tenase complex. C6 cells were also able to activate prothrombin in the presence of FXa and FVa, thus supporting formation of the prothrombinase complex. This ability was similar to positive controls performed with PS-containing vesicles. Accordingly, exposure of PS on C6 cells was demonstrated by flow cytometry employing specific anti-PS antibodies. In addition, annexin V, which blocks PS binding sites, inhibited FX and prothrombin conversion by their respective C6-assembled activating complexes.

CONCLUSION

C6 glioma cells support all procoagulant reactions leading to robust thrombin formation. This ability results from concomitant TF exposure and from the presence of the anionic lipid PS at the outer leaflet of cell membrane. Therefore, this animal cell line may be used to explore new aspects concerning the role of blood coagulation proteins in tumor biology, especially those affecting the central nervous system.

The role of thrombin in gliomas

BACKGROUND

In a previous study we found that intracerebral infusion of argatroban, a specific thrombin inhibitor, reduces brain edema and neurologic deficits in a C6 glioma model.

OBJECTIVES

To examine the role of thrombin in gliomas and whether systemic argatroban administration can reduce glioma mass and neurologic deficits and extend survival time in C6 and F98 gliomas.

METHODS

The presence of thrombin in human glioblastoma samples and rat C6 glioma cells (in vitro and in vivo) was assessed using immunohistochemistry. The effect of thrombin on C6 cell proliferation in vitro was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. The role of thrombin in vivo was assessed in rat C6 and F98 glioma cell models using argatroban, a thrombin inhibitor. The effects of argatroban on tumor mass, neurologic deficits and survival time were investigated.

RESULTS

Thrombin immunoreactivity was found in cultured rat C6 glioma cells and human glioblastomas. Thrombin induced C6 cell proliferation in vitro. In C6 glioma, argatroban reduced glioma mass (P < 0.05) and neurologic deficits (P < 0.05) at day 9. In F98 glioma, argatroban prolonged survival time (P < 0.05).

CONCLUSION

These results suggest that thrombin plays an important role in glioma growth. Thrombin may be a new therapeutic target for gliomas.

Systemic use of argatroban reduces tumor mass, attenuates neurological deficits and prolongs survival time in rat glioma models

Our previous studies showed that intracerebral infusion of argatroban, a specific thrombin inhibitor, reduces brain edema and neurological deficits in a C6 glioma model. The present study investigated whether systemic argatroban administration can reduce glioma mass and neurological deficits and extend survival time in C6 and F98 gliomas. Rat C6 or F98 glioma cells were infused into the right caudate of adult male Fischer 344 rats. Osmotic minipump loaded with argatroban (0.3 mg/hour) or vehicle was implanted into abdomen immediately after glioma implantation. Tumor mass was determined at day 9. Over the period of the experiment, the animals underwent behavioral testing (forelimb placing and forelimb use asymmetry). In addition, survival time was tested in the F98 glioma model. In C6 glioma, argatroban reduced glioma mass (p < 0.05) and neurological deficits (p < 0.05) at day 9. In F98 glioma, agratroban prolonged the survival time (p < 0.05) and reduced the body weight loss (84 +/- 15 gram vs. 99 +/- 2 gram in the vehicle group, P < 0.05). In conclusion, systemic use of argatroban reduced tumor mass and neurological deficits, and prolonged survival time. These results suggest that thrombin plays a key role in glioma growth and thrombin inhibition with argatroban may be a novel treatment for gliomas.

The coagulation system as a target for experimental therapy of human gliomas

The purpose of this paper is to review the rationale for the development of coagulation-reactive drugs for the experimental therapy of gliomas. Numerous reactants familiar to students of blood coagulation have been shown to contribute to neoplastic proliferation, invasion and metastasis. Recently, considerable progress has been made in demonstrating the ability of drugs capable of inhibiting these reactants to alter cancer progression. Biological features of gliomas within the realm of blood coagulation suggest that clinical trials of such drugs warrant consideration. This approach offers the prospect of a novel treatment for this devastating tumour type that does not share the toxicities of conventional cancer therapies.