CA2312824A1

CA2312824A1 - Use of a fibrinogen receptor-antagonist for preventing disseminated intravascular coagulation

Info

Publication number: CA2312824A1
Application number: CA002312824A
Authority: CA
Inventors: Gundula Wiemann
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-12-02
Filing date: 1998-12-02
Publication date: 1999-06-10
Also published as: DE19753383A1; EP1035868A1; WO1999027962A1; JP2001524534A

Abstract

The present invention relates to the use of fibrinogen receptor-antagonists for preventing disseminated intravascular coagulation (DIC) related to sepsis or systemic inflammatory response syndrome (SIRS) in humans.

Description

2. Dezember 1998 Miiller-Borb & Partner Applicant: Gundula Wiemann "Use of a fibrinogen receptor-antagonist for preventing disseminated intravascu-lar coagulation"
Our Ref: W 1620 - py / js Description The present invention relates to the use of fibrinogen receptor-antagonists for preventing disseminated intravascular coagulation (DIC) related to sepsis or systemic inflammatory response syndrome (SIRS) in humans.
An appropriate fibrinogen receptor-antagonist for the use according to the present invention is a platelet specific immunoglobulin fragment directed against the human glycoprotein gp Ilb/Illa receptor present on platelets, comprising an antigen binding region derived from monoclonal antibody 7E3. An example is the Fab fragment of a chimeric mouse-human antibody which is disclosed in WO
89/11538, and commercially available as the pharmaceutically effective com-pound Abciximab in the pharmaceutical composition ReoProT"", which has been developed by Centocor and is provided by Beiersdorf-Lilly GmbH.
It has been shown that the main fibrinogen receptor on the surface of platelets is the glycoprotein (gp) Ilb/Illa complex, which is a member of the integrin superfamily (Fitzgerald, L. A. et al. (1987) J. Biol. Chem. 262, 3936-3939;
Poncz, M. et al. (1987) J. Biol. Chem. 262, 8476-8482). The gp Ilb/Illa complex is composed of one molecule of gp Ilb (mol. wt. =140,000) which consists of a large (mol. wt. =125,000) and a small (mol. wt. = 25,000) polypeptide chain which are linked by one or more disulfide bonds, and one molecule of gp Illa (mol. wt. =105,000) which is a single polypeptide chain (Carrell, N. A. et al.
(1979) J. Biol. Chem. 260, 1743). A normal platelet contains about 50,000 to 80,000 gp Ilb/Illa complexes which represent about 1 % to 2% of the total platelet protein. Only about 70% of the gp 1Ibl111a complexes are randomly distributed on the exposed platelet surface (Isenberg, W. M. et al. (1987) J.
Cell Biol. 104, 1655), while the remaining so-called "cryptic" gp Ilb/Illa is distributed 2. Dszember 1998 Mullsr-BorB & Partner between the membranes of the surface-connected canalicular system (Woods, V. L. et al. (1986) Am. J. Path. 124, 324) and the membranes of the cytoplas-mic a-granules which release their contents upon platelet stimulation (Wencel-Drake, J. D. et al. (1985) J. Biol. Chem. 260, 1743). Thus, the gp Ilb/Illa recep-for is of main importance for the binding of fibrinogen to platelets and plays a key role in platelet aggregation. The symmetric fibrinogen molecule thereby functions as a link between the gp Ilb/Illa receptors of two adjacent platelets.
Fibrinogen receptor-antagonists inhibit platelet aggregation by blocking the binding site of fibrinogen on the surface of activated platelets. Various ant-agonists of the receptor complex are disclosed in the prior art. These include e.g. monoclonal antibodies (WO 89/11538, WO 90/06134, WO 95/12412), (cyclicl peptides comprising Arg-Gly-Asp (RGD) or Lys-Gly-Asp (KGD) amino acid motifs, respectively (WO 91 /1 1458; WO 92/17492), or structural analogs of such motifs (EP-A 0 454 651; WO 94/29349), the dodecapeptide His-His-Leu-Gly-Gly-Ala-Lys-Gln-Ala-Gly-Asp-Val (HHLGGAKC1AGDV) and analogues therof (Timmons et al. ( 1989) Biochemistry 28, 2919-2922), bicyclic compounds comprising two condensed six membered rings (WO 96/18602), and non-pepti-de compounds isolated from snake venom samples (WO 90/15620).
A focus of prior art studies has been the monoclonal anitbody 7E3 which was initially characterized by its ability of binding to the gp 1Ibl111a receptors of resting as well as activated platelets (Coller, B. S. et al. ( 1991 ) Ann. NY
Acad.
Sci. 614, 193-213). By means of in vitro assays it has been shown that c7E3 which represents a mouse-human chimeric variant of the antibody, inhibits the gp Ilb/Illa dependent aggregation of platelets in a dosage dependent manner.
This inhibition was independent of the tested stimuli for platelet aggregation such as ADP, collagen, thrombin, adrenalin, etc. In order to establish the relative extend of binding of 7E3 and of fragments thereof (Fab, Fab', F(ab')2) to plate-lets, direct binding studies using '251-labeled antibodies were performed. All forms of the 7E3 antibody bound to human platelets in a saturable fashion.
Platelets from different individuals exhibited different levels of 7E3 binding.
However, an average of approximately 80,000 molecules of 7E3 Fab as well as 2. Dezember 1998 Muller-Bor6 & Partner _ 3 7E3 Fab' are bound per platelet, in contrast to approximately 40,000 molecules of 7E3 IgG or 7E3 F(ab'12 fragments (Jordan, R. et al. (1991 ) Thromb.
Haemost.
65, 828). Similar studies also showed that approximately 80,000 molecules of the 'z51-labeled Fab' fragment of the mouse-human chimeric 7E3 (c7E3) are bound per platelet.
Therefore, the 7E3 antibody and its mouse-human chimeric variant c7E3 as well as Fab, Fab' or F(ab)2 fragments thereof have been proposed as agents for antithrombotic therapy of patients at risk for cardiac failure (Coller, B. S.
(1995) Circulation 92, 2373-2380).
This has led to the development of the drug ReoProT"" by Centocor, which is available from Beiersdorf-Lilly GmbH. ReoProT"" contains Abciximab as the pharmceutically effective compound, which is the Fab fragment of a mouse-human chimeric immunoglobulin comprising an antigen binding region derived from the highly variable region of the mouse antibody 7E3 and constant regions derived from human origin. According to the product description of ReoProT""
its use, in addition to heparin and acetylsalicylic acid, is restricted to the prevention or reduction of reocclusion following thrombolytic therapy and to accelerate the rate of thrombolyses in patients treated by percutane transluminal coronary angioplasty.
According to the product description, due to the increased bleeding tendency, the treatment with ReoProT"" should be further restricted to patients being at high risk for suffering from acute coronary thrombosis provided that the patient displays at least one of the following criteria:
1. Angina pectoris with the following symptomes:
therapy resistent angina at quiescent state along with ischemic ST
modifications, - therapy resistent, repeatedly appearing angina along with ischemic ST modifications, - therapy resistent angina post infarction along with ischemic ST

2. Dezember 1998 Muller-Borf & Partner modifications during the first 7 days post myocard infarction.
2. Acute transmural myocard infarction, which appeared not more than 12 hours before, and which deserves the following treatment:
- direct interventional procedure, - necessary measure after unsuccesful thrombolytic therapy.

3. Angiographically defined lesions within the coronary circuit narrowing the vascular volume:
- two features of a type B lesion, - one feature of a type C lesion, - women elder than 65 years of age displaying one feature of a type B lesion and/or suffering from diabetes mellitus.
It is further known that septic multiple organ dysfuction syndrome (MODS) and multiple organ failure (MOF) are still the major cause of death in post operative and post traumatic intensive care patients (Machiedo, G. W. et al. (1981) Ann.
Int. Med. 152, 757-759; Fourrier, F. et al. (1192) Chest 101, 816-832). Espe-cially prominent among the reasons for these complications are sepsis related to infections and a systemic inflammatory reaction which is referred to as "system-is inflammatory response syndrome" (SIRS) related to various clinical conditions such as shock, trauma, ischemia, pancreatitis, burn injury, surgery, etc.
(Bone, R. C. et al. (1992) Chest 101, 1644-1655). MODS and MOF, respectively, are thought to be a result of the excessive activation of humoral and cellular casca-de systems by endotoxins or related substances released into the blood stream (Bone, R. C. et al. ( 1991 ) Ann. Int. Med. 115, 457-469; Lowry, S. F. et al.
(1993) Arch. Surg. 128, 1235-1241 ).
It has been shown that MODS and MOF can be due to organ malperfusion caused by microcirculation disturbances. This often lethal complication is fre-quently found in cases of e.g. gram negative sepsis and characterized by the so-called disseminated intravascular coagulation (DIC). DIC is an early complication of sepsis, and characterized by the development of microclots in small vessels 2. Dezember 1998 Miiller-Bori & Partner of the large arterial circulation system. In these patients there is a tendency for bleeding as a consequence of an uncontrolled consumption of platelets and coagulation factors. The fibrin formation in the vessels causes ischemia which in turn results in functional disturbances of the organs. Moreover, intravascular 5 fibrin formation can contribute to the accumulation of leukocytes in the lungs, and thrombin leads to an increased translucence of the vessels. A developing DIC can thus represent a factor for triggering an acute dyspnea syndrome.
Despite the fact that activation of neutrophils is in itself not directly triggering the coagulation process, it may induce an increased release of cytokines such as interleukin-1 (IL-1 ), interleukin-6 (IL-6) and tumor necrosis factor (TNF) in pa tients suffering from sepsis, which promotes (a) the kallikreine/kinine system and (b) the complement system in addition to (c) the coagulation system, thus promoting disturbance in microcirculation and not at least formation of micro clots.
Finally, it can be stated that the activation of host defence system leads, on the one hand, to a generalized release of proinflammatory cytokines and, on the other hand, to a parallel down-regulation and consumption of natural inhibitors.
These changes ultimately produce an overspill of proinflammatory mediators (Bone, R. C. et al. (1992) Crit. Care Med. 20, 891-898) that may result in widespread endothelial damage and following platelet activation known to be a central mechanism in the pathogenesis of MODS and MOF, respectively (Gawaz, M. et al. (1995) Eur. J. Clin. Invest. 25, 843-851 ).
When blood vessels are damaged by an injury or other causative factors, plate-lets adhere to the disrupted subendothelial surface. The adherent platelets subsequently release biologically active constituents, and aggregate. Aggrega-tion is initiated by the binding of agonists, such as thrombin, epinephrine, or ADP to specific platelet membrane receptors. Stimulation by agonists results in exposure of latent fibrinogen receptors on the platelet surface, and binding of fibrinogen to the glycoprotein Ilb/Illa receptor complex.

2. Dezember 1998 Miiller-Borg & Partner Attempts to prevent MODS and MOF, respectively, have been made with anti-thrombin III (AT III), the most important natural inhibitor of thrombin activity as well as of many other serine proteases to rise inhibitors of the coagulation system (Wilson, R. F. et al. (1989) Am. Surg. 55, 450-456).
Despite the fact that AT III is consumed, and low AT III plasma activities correla-to with high mortality, not all clinical trials showed beneficial results under AT III
substitution.
There is a long list of attempts to modulate coagulation related to sepsis and SIRS. For example, synthetic proteinase inhibitors, hirudin and thrombin inhibi-tors have been used by Zawilska, K. et al. (Thromb. Res. (1995) 80, 99-104).
Recombinant soluble thrombomodulin has been used by Aoki, Y. et al. (Thromb.
Haemost. (1994) 71, 452-455). Factor Xa inhibition has been used by Hara, T.
et al. (Thromb. Haemost. ( 1995), 74, 635-639), who could not demonstrate an effect on bleeding time, etc.
However, all these studies failed to show clinical efficacy in well controlled phase II and III clinical trials.
The following list demonstrates the high all-cause mortality rate in 12 prospecti-ve controlled randomized, double-blind, multicenter trials involving 6266 pa-tients, including all important trials in the last years:
Methylprednisolone (placebo, n =190, mortality 25 %; agent, n =191, mortality 34%) in: Bone, R. C. et al. (1987) New Engl. J. Med. 317, 653-658.
Methylpredinsolone (placebo, n =11 1, mortality 22%; agent, n =112, mortality 21 %) in: Veterans Administration Systemic Sepsis Cooperative Group (1987) New Engl. J. Med. 317, 659-665.
HA-1 A (anti-I.PS) (placebo, n = 281, mortality 43%; agent, n = 262, mortality 39%) in: Ziegler, E. J. et al. (1991) New Engl. J. Med. 324, 429-436.
E5 (anti-LPS) (placebo, n = 239, mortality 43%; agent, n = 247, mortality 40%) in: Greenman, R. L. et al. (1991 ) J. Am. Med. Assoc. 266, 1097-1 102.

2. Dezember 1998 Muller-Bori & Partner Platelet-activating factor receptor-antagonist (placebo, n =150, mortality 51 %;
agent, n=132, mortality 42%) in: Dhainaut, J-F. A. et al. (1994) Crit. Care Med. 22, 1720-1728.
Recombinant human II-1 ra (placebo, n = 302, mortality 34%; agent, n = 591, mortality 30%) in: Fisher, C. J. et al. (1994) J. Am. Med. Assoc. 271, 1836-1843.
E5 /anti-LPS) (placebo, n=412, mortality 26%; agent, n=418, mortality 28%) in: Bone, R. C. et al. (1995) Crit. Care Med. 23, 994-1006.
Anti-TNF monoclonal antibody (placebo, n = 326, mortality 33%; agent, n = 655, mortality 30%) in: Abraham, E. et al. (1995) J. Am. Med. Assoc. 273, 934-941.
Anti-TNF monoclonal antibody (placebo, n =167, mortality 40%; agent, n =386, mortality 37%) in: Cohen, J. et al. (1996) Crit. Care Med. 24, 1431.1440.
TNF-R: Fe fusion proteins (placebo, n = 33, mortality 30%; agent, n =108, mortality 44%) in: Fisher, C. J. et al. (1996) New Engl. J. Med. 334, 1697-1702.
P55 TNF-R: Fe fusion proteins (placebo n =140, mortality 39%; agent, n = 358, mortality 35%) in: Abraham, E. et al. (1997) 277, 1531-1538.
Ibuprofen (placebo, n = 231, mortality 40%; agent, n = 224, mortality 37%) in:
Bernard, G. R. et al. (1997) New Engl. J. Med. 336, 912-918.
It has been suggested that the fibrinogen related platelet-platelet inteaction represents the so-called "final step" of platelet activation regardless of the pathway that leads to it, and that it plays also a role in DIC development. As a consequence of the activation, a conformational change of the gp Ilb/Illa recptor complex leads to the presentation of the entirety of the about 50,000 to 80,000 fibrinogen receptors contained within each platelet on their exposed surface.
In experiments utilizing an animal model of E. coli infection, F(ab')2 fragments of monoclonal antibody 7E3 were used to investigate the influence of this fibrino-gen receptor-antagonist on microvascular changes (Taylor, F. B: et al. (1997) Blood 89, 4078-4084). In this study, baboons were infected with E, coli and co-treated with C4b-binding protein (C4bBP). The group treated with 7E3 Flab')Z
fragments showed a positive effect on the survival rate. However, an extra-2. Dezember 1998 Miiller-Bor6 & Partner potation of these data to humans is impossible for several reasons. For example, the animals were pretreated with the antibody fragment prior to infection.
Second, the pathophysiology of the animal model and comparable human disorders is strikingly different. Moreover, the co-treatment of the baboons with the C4b-binding protein (C4bBP) in addition to the bacteria results in an artificial pathophysiological state which is never encountered in the treatment of human patients.
Therefore, the technical problem underlying the present invention is to provide a novel system for the prevention of disseminated intravascular coagulation (DIC) related sepsis or systemic inflammatory response syndrome (SIRS) in humans.
The solution to the above technical problem is provided by the emodiments characterized in the claims.
In particular, the present invention relates to the use of at least one fibrinogen receptor-antagonist for the preparation of a pharmaceutical composition for preventing disseminated intravascular coagulation (DIC) related to sepsis or systemic inflammatory response syndrome (SIRS), by blocking the fibrinogen receptors on platelets in humans.
The term "fibrinogen receptor-antagonist" comprises a molecule which is charac-terized by its ability to prevent fibrinogen from binding to its receptor. The receptor may be present on the surface of platelets. In a preferred embodiment of the present invention the receptor is the glycoprotein Ilb/Illa receptor.
In a further preferred embodiment of the present invention the fibrinogen recep-tor-antagonist is selected from the group consisting of Tirofiban and pharmaceu-tically effective derivatives thereof, Lamifiban and pharmaceutically effective derivatives thereof, Integrilin and pharmaceutically effective derivatives thereof, Fradafiban and pharmaceutically effective derivatives thereof, Xemilofiban and pharmaceutically effective derivatives thereof, Orbofiban and pharmaceutically 2. Dezember 1998 Muller-Bor6 & Partner effective derivatives thereof, Lefradafiban and pharmaceutically effective deri-vatives thereof, Clopidogrel and pharmaceutically effective derivatives thereof, peptides comprising the amino acid motif RGD and pharmaceutically effective derivatives thereof, peptides comprising the amino acid motif KGD and pharma-ceutically effective derivatives thereof, peptides comprising the amino acid sequence HHLGGAKQAGDV and pharmaceutically effective derivatives thereof, and immunoglobulins or biologically active fragments thereof. Preferably, the immunoglobulin is a mouse-human chimeric monoclonal antibody. It is further preferred that the chimeric mouse-human monoclonal antibody comprises the antigen binding region of the monoclonal antibody 7E3. An example of such a mouse-human chimeric antibody is c7E3. More preferably, the fibrinogen recep tor-antagonist is the Fab fragment of- the chimeric mouse-human monclonal antibody as defined before. An example of such an Fab fragment is the Fab fragment of c7E3 (Abciximab) which is contained in the drug ReoProT"" as the pharmaceutically effective ingredient.
The term "disseminated intravascular coagulation" means the formation of microclots in small vessels of the large arterial circulation system.
The term "sepsis" means the entirety of life-threatening clinical disorders and pathophysiological changes as a consequence of the action of pathogens and/or products thereof which invade from the place of infection into the blood stream, activating general biological cascades and special cellular systems, and triggering the release of humoral and cellular mediators. In a preferred embodiment of the present invention sepsis may be caused by an infection with pathogens selected from the group constisting of gram negative bacteria, gram positive bacteria, viruses, fungi and Plasmodia spec. Plasmodia spec. may comprise e.g. P. mala-riae, P. vivax, P, ovate, and P, falciparum.
According to the present invention, sepsis may be diagnosed according to one or more of the following criteria systems:
1. Criteria for sepsis according~to R. C. Bone et al. (Crit. Care Med. (1989) 2. Dezember 1998 MOller-Bord & Partner 17, 389-3931: clinically evident infection, plus:
- body temperature of 38,3°C or more, or of 35,6°C or less, when measured rectal, - tachycardia of 90/min or more 5 - tachypnoe of 20/min or more, and - evidence of at least one parameter of inadequate organ perfusion or organ dysfunction:
- change of mental state, - pa02 of 75 mmHg at room air, 10 - increased lactate serum concentration, and/or - diuresis of 30 ml/h or less.
2. Criteria for sepsis according to the Veterans Administration Systemic Sepsis Coorperation Group (New Engl. J. Med. (1987) 317, 659-665):
clinical suspection for sepsis and at least four of the symptomes selected from the group consisting of - chill and/or a body temperature of 38,9°C or more, or of 35,5°C or less, when measured rectal, - tachypnoe of 28/min or more, or hypocapnia of 32 mmHg paC02 or less, - tachycardia of 100/min or more, - systolic hypotension of 90 mmHg or less, - leukocyte count of 3,500/mm3 or less, or of 15,000/mm3 or more, - thrombocytopenia of 100,000/mm3 or less, - surgery intervention during the past 48 hours, and/or - obviously present primary source of sepsis.
3. Criteria according to Ziegler, E. J. et al. (New Engl. J. Med. (1991) 324, 429-436): suspection for gram negative infection, plus:
- body temperature of 38,3°C or more, or of 35,6°C or less, when measured rectal, and - tachycardia of 90/min or more, and tachypnoe (20/min or more, or necessity for mechanical ventilation by a respirator), 2. Dezember 1998 Muller-Bor6 & Partner or the patient further displays at least two of the symptomes indicating a systemic toxination or a peripheral hypoperfusion selected from the group consisting of - metabolic acidosis of unknown origin as evidenced by a pH 7,3 base excess (BE) of -5 mmol/L or more, or by hyperlactacidemia, - arterial hypoxemia of 75 mmHg pa02 or less, or of a quotient pa02/Fi02 of 250 or less, - acute renal failure with a diuresis of 0,5 ml/kg body weight/hour or less - thrombocytopenia of less than 100,000/mm3 or indicated by a reduction at least to the half of the number of platelets/mm3 than the normal range, or prolonged prothrombin time, or PTT, - sudden reduced consciousness, - increased cardiac index of 4 liters/min or more, accompanied by a total peripheral resistence of 800 dyn'*s/cms.

4. In addition to the criteria systems 1. to 3., the patient further displays one or more of the biochemical symptomes selected from the group consisting of - increased tumor necrosis factor (TNF) serum concentration - increased serum concentration of one or more of interleukines 1 to 6 (IL-1 to IL-6), - increased serum concentration of activated complement factors (C3a; C5a) - reduced antithrombin III (AT III) serum activity, - reduced 2-plasmin inhibitor serum activity, - increased serum concentration of arachidonic acid metabolites (thromboxanes, prostaglandines, leukotrienes) - detection of platelet activating factor (PAF) in the serum, and/or - detection of free oxygen radicals, peroxide, superoxide and/or hydroxyl in the serum.
The term "systemic inflammatory response syndrome (SIRS)" means a systemic 2. Dezember 1998 Mi~l~er-Borb & Partner _ 12 inflammatory response resulting in the same processes as defined above for the term "sepsis", but which can not be related to an infection by a pathogen, i.e.
no positive blood culture.
According to a preferred embodiment of the present invention SIRS may be caused by shock, trauma, ischemia, pancreatitis, burn injury, and/or surgery.
SIRS may be diagnosed according to the criteria for sepsis as defined above.
A further embodiment of the present invention relates to a method for treating a human patient at risk for suffering from DIC caused by sepsis or SIRS com-prising administering a pharmaceutical composition comprising a pharmceutically effective amount of at least one fibrinogen receptor-antagonist, and thereby blocking the fibrinogen receptors on platelets. This means that the human patient should exhibit at least one of the above defined criteria for sepsis or SIRS
before administering the pharmaceutical composition according to the present invention.
According to a preferred embodiment of the method of the present invention sepsis may be caused by infection with the pathogens as defined above.
According to a further preferred embodiment of the method of the present invention SIRS may be caused by the conditions as defined above.
According to a further preferred embodiment of the method of the present invention, the pharmaceutically effective amount of the fibrinogen receptor-antagonist is sufficient for blocking of about 80% or less of the fibrinogen receptors contained within the platelets of the human patient.
According to a further preferred embodiment of the method of the present invention, the fibrinogen receptor-antagonist may be selected from the group as defined above.
According to a preferred embodiment of the method of the present invention, 2. Dezember 1998 Miiller-Bor6 & Partner _ 13 the pharmaceutical composition is administered by bolus injection comprising an amount of the Fab fragments of about 0.25 mg/kg body weight, followed by infusion of an amount of the Fab fragments of about 10 ,ug/min over 12 h or less.
The use of a fibrinogen receptor-antagonist according to the present invention is described hereinafter by the following non-limiting example.
EXAMPLE
The example uses the Fab fragments of the mouse-human chimeric antibody derived from monoclonal antibody 7E3 (also referred to as Abciximab) specific for gp Ilb/Illa as the fibrinogen receptor-antagonist.
Surprisingly, Abciximab exhibits an especially high efficacy in the prevention of microcirculation disturbances and in the improvement of microcirculation after an occurrence of microcirculation disturbances, respectively, as they are caused by sepsis or SIRS. Thus, the risk for MOF is advantageously reduced.
According to the product description of ReoProT"", initially a dosage is suggested comprising an intravenous bolus injection (0.25 mg/kg body weigth) followed by continuously intravenous infusion at a rate of 10 ,ug/min.
Therefore, the application may be generally carried out by continuously in-travenous infusion of a dosage of not more than 10 ,ug Abciximab/min, or by bolus injection of 0.25 mg/kg body weight, followed by infusion of 10,ug/min over 12 hours or less.
By this treatment it is possible to adjust the binding kinetics so as to minimally interfere with actually occurring coagulation procedures in wound and/or surgery areas.
Therefore, the proposed dosage relates to the known value from the product 2. Dezember 1998 Muller-Borb & Partner description of ReoProT"", which is sufficient for blocking of about 80% of the fibrinogen receptors present on the exposed surfaces of the activated platelets of the patient. However, the dosage may be less if there is just a moderate platelet activation.
Especially important for the use according to the present invention is the mo-ment for administering the fibrinogen receptor-antagonist, since the proposed dosage does not achieve dissolving of existing platelet aggregates, but su-presses the formation of new platelet aggregates. As far as platelet aggregation has been already initialized, this will be reduced and suppressed in the further course of treatment.
In general, two regimens are suitable:
1. Prophylactical administration of the antibody immediately after the diagno-sis of sepis or SIRS. In this case, the dosage may remain below the above proposed dosage, provided that the degree of platelet activation and platelet count do not differ substantially from their normal range.
2. Administration of the antibody as soon as an increased platelet activation and a simultaneous reduction of circulating platelets is recognized. In this case, the dosage proposed above can be regarded as a recommended dosage which can shortly be exceeded until the values of the above parameters, or at least their tendencies, are stabilized.
The platelet activity is measured by means of flow cytometric analysis of the patient's blood sample using one or more of the following markers specific for molecules on the surface of activated platelets:
- RUU-SP 2.41 IgG 1 (Heynen, H. F. G. et al. ( 1994) J. Clin. Invest. 94, 1098-1112), kindly provided by Dr. Nieuwenhuis, and FITC-labeled by resarch laboratory of the University of Leipzig, Germany; RUU-SP 2.41 IgG 1 does not react with resting platelets;

' 2. Dezember 1998 Miiller-Borb & Partner - FITC-labeled P2 IgG 1 (Coulter-Immunotech); reacts with gp Illa;
- FITC-labeled P-selectin (CD 62-p) (Coulter-Immunotech); specific for GMP-140 of activated platelets; and/or - FITC-labeled PAC-1; does only react with a ligand induced binding site of 5 activated platelets (Shattil, S. J. et al. ( 1985) J. Biol. Chem. 260, 1 1 11114).
The flow cytometric analyses are carried out using a Coulter XL Epics Flow Cytometer (Coulter-Immunotech).
Blood samples are collected into a Sarsted tube every 2 hours from patients who showed at least one of the sepsis criteria 1. to 4. as described above.
Simulta-neously, haemodynamic monitoring, blood-gas analysis, and measurement of ventilation parameters are carried out. An aliquot of blood is mixed with PBS
(phosphate budffered saline), fixed and stained for a two-colour analysis method according to Koksch, M., and Wittig, K. (Ann. Haematol. (1997) 173).
Flow cytometric analysis of an aliquot of blood sample is carried out with each of the platelet activation markers given above by measuring the mean intensity of the FITC fluorescence of each FITC-labeled marker.
In each case the flow-cytometric signal detected in the patient's blood sample is compared with that of a mean value of a group of controls.

Claims

1. Use of at least one fibrinogen receptor-antagonist for the preparation of a pharmaceutical composition for preventing disseminated intravascular coagulation (DIC) related to sepsis or systemic inflammatory response syndrome (SIRS), by blocking the fibrinogen receptors on platelets in humans.

2. The use according to claim 1, wherein the fibrinogen receptor is the glyco-protein IIb/IIa receptor.

3. The use according to claim 1 or 2, wherein the fibrinogen receptor-ant-agonist is selected from the group consisting of Tirofiban, Lamifiban, Integrilin, Fradafiban, Xemilofiban, Orbofiban, Lefradafiban, Clopidogrel, peptides comprising the amino acid motif RGD, peptides comprising the amino acid motif KGD, peptides comprising the amino acid sequence HHLGGAKQAGDV, and pharmaceutically effective derivatives thereof, and immunoglobulins or biologically active fragments thereof.

4. The use according to claim 3, wherein the immunoglobulin is a mouse-human chimeric monoclonal antibody.

5. The use according to claim 4, wherein the mouse-human chimeric antibody comprises the antigen binding region of the monoclonal antibody 7E3.

6. The use according to anyone of claims 1 to 3, wherein the fibrinogen receptor-antagonist is the Fab fragment of the mouse-human chimeric antibody c7E3.

7. The use according to anyone of claim 1 to 6, wherein sepsis is caused by an infection with pathogens selected from the group constisting of gram negative bacteria, gram positive bacteria, viruses, fungi and Plasmodia spec.

8. The use according to anyone of claims 1 to 6, wherein the SIRS is caused by shock, trauma, ischemia, pancreatitis, burn injury, and/or surgery.

9. A method for treating a human patient at risk for suffering from DIC
related to sepsis or SIRS comprising administering a pharmaceutical composition comprising a pharmaceutically effective amount of at least one fibrinogen receptor-antagonist, and thereby blocking the fibrinogen receptors on platelets.

10. The method according to claim 9, wherein sepsis is caused by an infection with pathogens selected from the group constisting of gram negative bacteria, gram positive bacteria, viruses, fungi and Plasmodia spec.

11. The method according to claim 9, wherein SIRS is caused by shock, trauma, ischemia, pancreatitis, burn injury, and/or surgery.

12. The method according to anyone of claims 9 to 11, wherein the pharmaceutically effective amount of the fibrinogen receptor-antagonist is sufficient for blocking of about 80% of the fibrinogen receptors on the platelets of the human patient.

13. The method according to anyone of claims 9 to 12, wherein the fibrinogen receptor is the glycoprotein IIb/IIIa receptor.

14. The method according to claim 13, wherein the fibrinogen receptor-ant-agonist is selected from the group as defined in claim 3.

15. The method according to claim 14, wherein the immunoglobulin is a mouse-human chimeric monoclonal antibody.

16. The method according to claim 15, wherein the mouse-human chimeric antibody comprises the antigen binding region of the monoclonal antibody 7E3.

17. The method according to anyone of claims 9 to 14, wherein the fibrinogen receptor-antagonist is the Fab fragment of the mouse-human chimeric antibody c7E3.

18. The method according to claim 17; wherein the pharmaceutical composition is administered by bolus injection comprising an amount of the Fab fragments of about 0.25 mg/kg body weight, followed by infusion of an amount of the Fab fragments of about 10 µg/min over 12 h or less.