The coagulative factors of normal human and human cancer tissue

Treatment of advanced breast cancer with chemotherapeutics and inhibition of coagulation and fibrinolysis

A case of advanced breast cancer with cerebral metastasis and pleurisy is reported in which irradiation and cytostatics had failed to retard progressive growth and spread of the tumour. Adjuvant therapy with heparin combined with the fibrinolytic inhibitor tranexamic acid was followed by regression of the cerebral metastasis as well as the pleurisy. When last seen one year later, the patient was free from symptoms.

Thrombosis and hemorrhage in oncology patients

As outlined in this review, patients with cancer may harbor many alterations of hemostasis. These are multifaceted and must be considered when trying to control hemorrhage or thrombosis in cancer patients. Also, hemorrhage or thrombosis is often the final fatal event in many patients with metastatic solid tumor or hematologic malignancies. Patients with malignancy present a major clinical challenge in this new era of oncologic awareness and more aggressive care, which has led to prolonged survival for patients and a longer time frame during which these complications may develop. Therefore, these complications are occurring more commonly. It is important to realize that these alterations of hemostasis exist and must be approached in a sequential and logical manner with respect to diagnosis; only in this way can responsible, efficacious, and rational therapy be delivered to patients. By far the most common alteration of hemostasis in malignancy is that of hemorrhage associated with thrombocytopenia, either drug-induced, or radiation-induced, or from bone marrow invasion. Hemorrhage resulting from DIC, however, is also quite common and may present as hemorrhage, thrombosis, thromboembolus, or any combination thereof. Many antineoplastic drugs and radiation therapy may lead to or significantly enhance hemorrhage in patients with malignancy. Thrombosis, also commonly seen in patients with malignancy, is often a manifestation of low-grade DIC. When approaching the patient with malignancy and either hemorrhage or thrombosis, all the potential defects in hemostasis must be considered, defined from the laboratory standpoint, and treated in as precise and logical manner as possible.

Cancer procoagulant

Cancer procoagulant is a unique cysteine proteinase. The enzyme has been purified by several procedures and many of its characteristics and enzymatic properties have been determined. Several sensitive and reproducible assays are now available. Many proteinase inhibitors have been evaluated for their effect on CP; most low molecular weight inhibitors work well in a reduced environment. In the foreseeable future, protein and gene sequence information, expression vectors, molecular probes, and highly specific antibodies and inhibitors should provide the research tools to delineate a functional understanding of CP at the molecular and cellular level.

Hemostasis in malignancy

Hemostatic abnormalities are present in a majority of patients with metastatic cancer. These abnormalities can be categorized as 1) increased platelet aggregation and activation, 2) abnormal activation of coagulation cascade, 3) release of plasminogen activator, and 4) decreased hepatic synthesis of anticoagulant proteins like Protein C and antithrombin III. The abnormal activation of coagulation cascade is mediated through release of Tissue Factor, Factor X activators, and other miscellaneous procoagulants from the plasma membrane vesicles of tumor cells. Macrophages of a tumor-bearing host also produce increased amounts of Tissue Factor. Production of Factor X activators and macrophage Tissue Factor is decreased by warfarin. The ability of the tumor cells to produce platelet-aggregating activity and plasminogen activator parallels their metastatic potential in animal and experimental systems. These studies also show that antiplatelet agents and antibodies against plasminogen activator can suppress the metastatic process. One or more laboratory abnormalities of hemostasis can be shown in up to 95% of patients with metastatic cancer. These abnormalities, however, are unable to predict subsequent development of thromboembolic or hemorrhagic complications. Clinical complications occur in 9-15% of the patients in the form of thrombotic or hemorrhagic disorders. The therapy of tumor-related coagulopathy should be guided by its clinical expression. Subclinical DIC should not be treated. Coumadin is generally ineffective for therapy of thrombosis in cancer patients. There is no consensus regarding the use of heparin in acute promyelocytic leukemia (APL). The defibrination in APL may be from disseminated intravascular coagulation as well as systemic fibrinolysis, as shown by decreased alpha 2 antiplasmin levels. In such cases, epsilon aminocaproic acid plus heparin therapy may be of benefit.

Several murine metastasizing tumors possess a cysteine proteinase with cancer procoagulant characteristics

Cancer Procoagulant (CP), a cysteine proteinase which triggers blood coagulation by directly activating Factor X (FX) in the absence of Factor VII (F VII), has recently been isolated from rabbit V2 carcinoma and biochemically characterized. We have studied the procoagulant activity of tissue extracts from 4 murine experimental tumors in order to define whether or not a F VII-independent activity with cysteine proteinase characteristics was present. The tumors studied were: Lewis lung carcinoma (3LL), B16 melanoma (B16), JW sarcoma (JWS) and the M4 variant of the mFS6 fibrosarcoma (M4). Extracts from 3LL, B16 and JWS tumor initiated coagulation in both the presence and absence of F VII, their procoagulant activity was sensitive to iodoacetamide (1 mM) and mercury chloride (0.1 mM). The procoagulant of M4 extract was dependent on the presence of F VII and was not significantly affected by the cysteine proteinase inhibitors. An Ouchterlony double immunodiffusion study showed immunological cross-reactivity of all but M4 extracts to a polyclonal antibody to purified CP. The present study suggests that the procoagulant(s) present in the murine tumors 3LL, B16 and JWS are enzymatically and immunologically indistinguishable from cancer procoagulant of the rabbit V2 carcinoma.

Role of plasma, platelets, and endothelial cells in tumor metastasis

This review studies interactions of tumor cells with a particular host system which is normally responsible for hemostasis and the physiological integrity of the blood vessel luminal surface. With malignancy components of this system are frequently activated, producing abnormalities of blood coagulation, increased platelet responses, and conditions favoring tumor growth and metastasis. Activation of the clotting cascade is mediated by tumor and macrophage procoagulants, acting via Factor X or VII. Thrombin and fibrin are formed. Thrombin also interacts with platelets and the endothelium, potentiating or decreasing coagulation. Generation of thrombin or other tumor mechanisms activate platelets, leading to direct aggregation or secretion of ADP, serotonin, and/or intermediates of the arachidonate metabolism. Vascular lesions caused by tumor attack, platelet secretion, or exogenous agents promoting metastasis may also activate the hemostatic system. It is not yet fully understood how activation of the clotting system, including platelets, contributes to metastasis. Secretion of platelet products appears, however, to be heavily involved. Based on putative mechanisms of action, anticoagulants, platelet inhibitors, thrombocytopenic or vascular repairing agents have been used to control tumor spread. Results depended on the agent and experimental model of metastasis used. Except for coumarin, which was beneficial even against spontaneous metastases, other anticoagulants and platelet inhibitors, excluding perhaps Nafazatrom, gave equivocal results. Thrombocytopenic agents, however, were effective in every tumor system and with any experimental model of metastasis, indicating that platelets play a role in this process. Also consistent were the inhibitory effects of leech salivary gland extract (probably a vascular repairing agent) against lung tumor colonization promoted by ionizing radiation, cyclophosphamide, and cortisone.

[The significance of fibrin/fibrinogen for growth and metastasis of malignant tumors (author's transl)]

It seems evident that fibrinogen and fibrin representing the final substrate und product of clotting system act as pathogenetic connecting links for development and spread of malignant tumors. The results reported demonstrate the influence of fibrin on the initial phase of haematogenic metastasis particularly. Several tumor-specific mechanisms are shown to cause frequently an accumulation of fibrin in malignant tumors. The results discussed here stress the importance of fibrin in tumors for tumor cells and tumor cell units. In the literature a large number of indications to fibrin depositions in experimental tumors is found, an attempt is made to compare these findings semiquantitatively. The last part of this article discusses the therapeutic and diagnostic consequences based on the possible key position of fibrin-(ogen) in the tumor pathology.

Thrombogenic activity of mouse and human tumors: effects on platelets, coagulation, and fibrinolysis, and possible significance for metastases

Twelve mouse tumors and 29 human malignancies were assayed in vitro for their capacity to aggregate platelets and induce release of radiolabelled serotonin, and for their ability to coagulate blood plasma and digest the fibrin clot. It was discovered that many human and mouse tumors can induce release of radiolabelled serotonin but that the quantitative relationships between this activity of tumors and their capacity to aggregate platelets was variable, permitting tumors to be classified into 3 different types. The procoagulant and fibrinolytic activity was also quite variable. Since no correlation was found between the 4 assayed tumor activities they appear to be independent, separate thrombogenic properties of tumors. Although the information gathered by this study is still fragmentary, some speculations can be made about the role of these activities in treatment of malignant tumors and in determing patterns of body distribution and control of metastases.