US 5,504,067 AGrant
Treatment of Bleeding With Modified Tissue Factor in Combination With FVII
Issue Date:1996-04-02
•20 Claims
•1 Drawing Sheets
Abstract
It has been discovered that it is possible to administer truncated tissue factor, not having the transmembrane region (tTF) in combination with factor VIIa (FVIIa) to treat bleeding disorders such as those resulting from hemophilia or cirrhosis of the liver. Preferably, the tTF is administered to produce up to 10 .mu.g tTF/ml of plasma. The FVIIa is administered to produce levels of between 40 ng FVIIa/ml and 4 .mu.g FVIIa/ml of plasma. The effective dosages of both tTF and FVIIa are significantly and surprisingly less than the administration of either alone to stop bleeding. Examples demonstrate safety and efficacy in normal and hemophilic dogs.
Metadata
Assignee
- Oklahoma Medical Research Foundation
Inventors
- James H. Morrissey
- Philip C. Comp
Application Information
Application Number:US 3217779
Filing Date:1994-10-12
Priority Date:1992-05-13
Art Unit:185
Classifications
IPC:
A61K 3514A61K 3848A61K 3816C07K 14745
Field of Search:
530514350;380;395;381;384;829;8308;12;21;834;802
Patent Drawings (1 sheets)
Description
BACKGROUND OF THE INVENTION
Blood coagulation results from the production of thrombin, a proteolytic enzyme inducing platelet aggregation and cleaving fihrinogen to fibrin, which stabilizes the platelet plug. A number of proenzymes and procofactors circulating in the blood interact in this process through several stages during which they are sequentially or simultaneously converted to the activated form, ultimately resulting in the activation of prothromhin to thromhin by activated Factor X (fXa) in the presence of Factor Va, ionic calcium, and platelets.
Factor X can he activated by either of two pathways, termed the extrinsic and intrinsic pathways. The intrinsic pathway, or surface-mediated activation pathway, consists of a series of reactions where a protein precursor is cleaved to form an active protease, beginning with activation of Factor XII to Factor XIIa, which converts Factor XI to Factor XIa, which, in the presence of calcium, converts Factor IX to Factor IXa. Factors IX and X can also he activated via the extrinsic pathway by tissue factor (TF) in combination with activated Factor VII (Factor VIIa; FVIIa). Activated Factor IX, in the presence of calcium, phospholipid (platelets), and Factor VIIIa, activates Factor X to Factor Xa.
Physiologically, the major pathway involved in coagulation is believed to be the extrinsic pathway, an essential step of which is tissue factor-mediated activation of Factor VII to Factor VIIa. Tissue factor is an integral membrane glycoprotein having a protein and a phospholipid component. It has been isolated from a variety of tissues and species and reported to have a molecular mass of between 42,000 and 53,000. DNA encoding tissue factor and methods for expression of the protein have now been reported, for example, in European Patent Application 0 278 776 by Genentech, Inc. and by J. H. Morrissey, et al. Cell 50:129-135 (1987).
The complex of Factor VIIa and its essential cofactor, TF, is the most potent known trigger of the clotting cascade. Factor VII is present in plasma at a concentration of 0.5 .mu.g/ml plasma. In contrast, Factor VIIa is present in plasma at trace levels of roughly 1 ng/ml. Accordingly, Factor VII is normally in considerable excess over Factor VIIa. Factor VIIa circulates with a relatively long half-life of about two hours in plasma. This is an unusual property among activated coagulation enzymes, which typically are inactivated very rapidly by various protease inhibitors in plasma.
Hemophilia A is characterized by the absence of active coagulation Factor VIII or the presence of inhibitors to Factor VIII. Hemophilia B is characterized by the absence of active Factor IX. Both types of hemophilia are associated with bleeding diatheses that can lead to crippling injuries or death. Traditionally, patients with either type of hemophilia were treated with infusion of plasma concentrates to stop bleeding episodes. The problems with the concentrates are many, especially infection, most recently with HIV. Highly purified Factor VIII or Factor IX have been introduced to obviate these problems, as have methods of treating factor concentrates to inactivate viruses. However, some patients develop high-titer, inhibitory antibodies to Factor VIII. Therefore, such patients can no longer be treated with conventional Factor VIII replacement therapy.
As described by Hedner and Kisiel, J Clin Invest 71:1836-1841 (1983), purified naturally produced Factor VIIa can be administered to hemophilia A patients with high titers of antibodies against Factor VIII:C and restore hemostasis in these patients. As reported by Brinkhous, et al., Proc Natl Acad Sci USA 86:1382-1386 (1989), recombinant Factor VIIa (rFVIIa) can be administered to hemophilic and von Willebrand disease dogs and stop bleeding in both hemophilic A and B dogs, but not the von Willebrand disease dogs. Telgt, et al., Thrombosis Res 56:603-609 (1989), reported that, at high levels, rFVIIa was believed to act by direct activation of Factor X, in the presence of calcium and phospholipid but in the absence of TF. Teitel, Thrombosis and Haemostasis 66:559-564 (1991), reported that the important ingredient in prothrombin complex concentrates for efficacy in treating hemophilia is Factor VIIa.
Hedner, "Experiences with Recombinant Factor VIIa in Haemophiliacs" in Biotechnology of Plasma Proteins. Curr Stud Hematol Blood Transf, Lenfant, Mannucci, Sixma, eds., No. 58, 63-68 (1991), review the use of prothrombin complex concentrates (effective in only 50 to 60% of the bleeds), as well as the use of plasma-derived (pFVIIa) and recombinant Factor VIIa (rFVIIa). Dosages of 10 to 15 .mu.g/kg of pFVIIa were effective in some hemophilia A patients. Safety studies in dogs and rabbits indicated that the recombinant Factor VIIa was safe and efficacious at dosages of up to 150 .mu.g/kg. A number of patients were also successfully treated, using dosages of between 54 .mu.g/kg and 90 .mu.g/kg during surgery and bleeding complications. Gringeri, et al., reported that treatment of hemophiliacs with rFVIIa is not always effective, even at dosages of 75 .mu.g/kg at intervals of every two to three hours. The authors noted that perhaps larger dosages, more frequent infusions, and/or the concomitant use of antifibrinolytic medication might be required in such cases. rFVIIa is currently in clinical trials in the United States for treatment of hemophilia, particularly hemophilia in patients with inhibitors who do not benefit from conventional Factor VIII or Factor IX replacement therapy. Doses of rFVIIa currently employed are typically 45 to 90 .mu.g rFVIIa/kg body weight, and are repeated every two to four hours. These doses are designed to achieve a level of circulating rFVIIa of approximately 4 .mu.g/ml, extremely high compared to the normal plasma concentrations of FVII of approximately 0.5 .mu.g/ml or FVIIa of approximately 1 ng/ml.
O'Brien, et al., J Clin Invest 82:206-211 (1988), reported that apo-TF, a delipidated preparation of the normally lipid-associated TF glycoprotein could be used to normalize bleeding in animals having antibodies to Factor VIII. Since purified apo-TF is inactive unless incorporated into a phospholipid membrane, the theoretical basis for infusing apo-TF is the hypothesis that it would spontaneously and preferentially incorporate into exposed membrane surfaces, particularly into damaged cells at the sites of injury. Subsequent studies have indicated there are dangers associated with the use of purified apo-TF in the treatment of hemophilia. The apo-TF can spontaneously incorporate into many types of lipid membranes and become active at sites where clotting is not desired, resulting in thrombosis or disseminated intravascular coagulation (DIC). Indeed, O'Brien, et al., reported evidence of DIC in some animals receiving apo-TF, and Sakai and Kisiel, Thromb Res 60:213-222 (1990), recently demonstrated that apo-TF will spontaneously combine with plasma lipoproteins to form active TF. This latter phenomenon is cause for concern because of a number of studies which have demonstrated that intravenous administration of active TF is a potent inducer of DIC.
Recently, a soluble, truncated form of TF (tTF) has been reported which retains some cofactor function towards Factor VIIa as measured in vitro using purified proteins. However, this form of TF has been dismissed as an alternative to TF because it has almost no procoagulant activity when tested with normal plasma, as reported by Paborsky, et al., J Biol Chem 266:21911-21916 (1991).
As described in U.S. Ser. No. 07/683,682 entitled "Quantitative Clotting Assay for Activated Factor VII" filed Apr. 10, 1991 by James H. Morrissey, the reason tTF was reported to lack procoagulant activity in the prior art is because, although tTF retains cofactor function toward Factor VIIa, tTF had lost the ability to promote conversion of Factor VII to Factor VIIa. As a consequence, tTF can clot plasma only in conjunction with significantly elevated levels of Factor VIIa, as compared to normal plasma, which contains only trace levels of Factor VIIa.
It is therefore an object of the present invention to provide a method and composition for treatment of significant bleeding disorders, such as hemophilia, including those hemophiliacs with high titers of anti-Factor VIII antibodies.
It is a further object of the present invention to provide a method and compositions for treatment of patients with bleeding disorders that are relatively safe and can be produced in commercial quantities.
SUMMARY OF THE INVENTION
It has been discovered that it is possible to administer truncated tissue factor (not having the transmembrane region) (tTF) in combination with Factor VIIa (FVIIa) to treat bleeding disorders such as, for example, those associated with hemophilia or cirrhosis of the liver. The tTF is administered to produce up to 10 .mu.g tTF/ml of plasma. The FVIIa is administered to produce levels of between 40 ng FVIIa/ml and 4 .mu.g Factor VIIa/ml of plasma. The minimal effective dosages of both tTF and FVIIa are significantly and surprisingly less than the administration of either alone to stop bleeding.
Examples demonstrate safety and efficacy in normal and hemophilic dogs.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a graph of dilute thromboplastin clotting time (seconds) for Factor VIII-deficient plasma when tTF and FVIIa (ng/ml) are added (dark triangles) or when FVIIa alone (ng/ml) are added (dark circles).
FIG. 1b is a graph of dilute thromboplastin clotting time (seconds) for normal plasma when tTF and FVIIa (ng/ml) are added (dark triangles) or when FVIIa alone (ng/ml) are added (dark circles).
DETAILED DESCRIPTION OF THE INVENTION
Truncated tissue factor (tTF) is used as an adjuvant for Factor VIIa (FVIIa) therapy of excessive bleeding in patients such as hemophiliacs. The tTF is administered in combination with the FVIIa, or immediately before or after the FVIIa. The minimal effective dosage of FVIIa is significantly decreased by the tTF, while the thrombogenicity of the mixture is reduced as compared to a mixture of FVIIa and TF in its native form.
The advantage, and necessity, of using a combination of FVIIa plus tTF over tTF alone is that tTF is active in promoting blood clotting only in the presence of pre-formed FVIIa. The advantage of using the combination of FVIIa plus tTF over FVIIa alone is that FVIIa is approximately 22-fold more potent at clotting plasma in the presence of tTF than in the absence of tTF. Furthermore, as with FVIIa alone, the complex of tTF plus FVIIa activates Factor X at markedly enhanced rates in the presence of negatively charged phospholipids such as phosphatidylserine, even though tTF is not itself incorporated into lipid membranes. Normally, negatively charged phospholipids are sequestered into the inner leaflet of the plasma membrane of cells, and thus are not exposed to the cell surface unless the cells are damaged, or, in the case of platelets, the platelets have undergone surface activation. Thus, negatively charged phospholipids should be preferentially exposed on cell surfaces at anatomic sites that have experienced trauma sufficient to cause cell lysis and/or platelet activation. This means that the complex of tTF and FVIIa is predicted from in vitro studies to be active in promoting blood clotting preferentially at sites of injury, where it would be needed to confer hemostasis. Furthermore, tTF, by itself or in complex with FVIIa, remains a soluble entity and does not become incorporated into lipid membranes. This means that it should clear relatively rapidly from the circulation, diminishing the risk of thrombosis. Because of these properties, the complex of tTF and FVIIa should not cause systemic activation of the blood clotting system leading to DIC, as can injection of wild-type TF. These in vitro results are consistent with results from in vivo studies in normal and hemophiliac dogs described below.
The combination of tTF plus FVIIa should be useful for treatment of hemophilia A, hemophilia B, congenital or acquired deficiencies in any other blood coagulation factor, or platelet defects. Other patients that can be treated with the combination include patients suffering from severe trauma, postoperative bleeding or those with cirrhosis.
Truncated Tissue Factor
As used herein, "truncated tissue factor" is a soluble tissue factor having only the extracellular domains, which is not bound to a phospholipid membrane surface, and therefore does not support conversion of FVII to FVIIa, as described in U.S. Ser. No. 07/683,682 filed Apr. 10, 1991, corresponding to International Application PCT/US92/02898 filed Apr. 9, 1992, the teachings of which are incorporated herein. In the preferred embodiment, truncated tissue factor is a recombinant protein produced in vitro in cell culture using a mammalian cell line such as CHO-K1 cells, American Type Culture Collection CCL 61. These cells are stably transfected with a mutant form of the human tissue factor cDNA carried in a commercially available expression vector, and secrete a form of tissue factor consisting only of amino acids 1-219 (numbered according to Morrissey, et al., Cell 50:129-135 (1987), the teachings of which are incorporated herein).
The recombinant, truncated tissue factor is purified from the culture medium using an immobilized monoclonal antibody to human tissue factor, such as TF9-5B7, described in Morrissey, et al., Thromb Res 52:247-261 (1988). Hybridomas for production of monoclonal antibodies can be propagated by ascites growth and the monoclonal antibodies (MAbs) purified from ascites fluid using the BioRad MAPS II system for mAb purification, as described by Morrissey, et al., Thromb Res 52:247-261 (1988).
The TF9-5B7 is coupled to Affigel.TM. beads. Detergent is not used during the purification of TF.sub.219. After removal of cellular debris by centrifugation, the culture medium is made 25 mM in Tris.HCl (pH 7.4), 10 mM in sodium EDTA (pH 7.4), and 0.1% in sodium azide by the addition of concentrated stock solutions. In order to remove proteins that bind to agarose beads non-specifically, the culture medium is gently agitated for 4 hr at 4.degree. C. with AffiGel.TM.-10 beads that had previously been blocked chemically with glycine ethyl ester (GEE-AffiGel). The GEE-AffiGel beads are removed by filtration through a sintered glass funnel, and the supernatant is agitated overnight at 4.degree. C. with the MAb TF9-5B7 coupled to AffiGel beads (typically 2 ml of beads). The TF9-5B7-AffiGel beads are collected on a sintered glass funnel, and the beads are washed on the funnel with 100 ml of TBS-EDTA (TBS=100 mM NaCl, 50 mM Tris.HCl (pH 7.4) and 0.02% sodium azide; TBS-EDTA=TBS with 10 mM EDTA included). The beads are then transferred to a chromatography column and washed with 40 ml TBS followed by 40 ml of a solution consisting of 1 M NaCl, 10 mM Tris. HCl (pH 7.4), and 0.02% sodium azide. Truncated TF is eluted from the beads using 100 mM glycine. HCl (pH 2.5), with 1 ml fractions being collected into tubes containing 57 .mu.l 1 M Tris base (to immediately neutralize the acidic glycine buffer). Fractions containing protein are detected using the BCA protein assay (Pierce Chemical Co., Rockford, ILL.), pooled, dialyzed against TBS, and then stored at -70.degree. C. Protein concentrations are determined using standard methods such as the BCA assay (Pierce Chemical Co.) based on a bovine serum albumin standard of known concentration.
For production of recombinant truncated TF, cells are typically grown to confluence in roller bottles in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% iron-supplemented calf serum (HyClone Laboratories, Logan, Utah). Upon reaching confluence, the cultures are shifted to DMEM containing 2% serum, and culture medium is collected every four days thereafter.
The nucleotide and amino acid sequence of truncated tissue factor (tTF) is shown below as SEQ ID NO:1 and SEQ ID NO:2, respectively. The truncated tissue factor protein lacks the predicted transmembrane and cytoplasmic domains of tissue factor. This version of the protein retains cofactor activity, as reported by Ruf, et al., Thromb Haemost 62:347 (abstract) (1989) and Ruf, et al., J Biol Chem 266:2158-2166 (1991). This truncated form of tissue factor fails to support conversion of Factor VII to Factor VIIa, allowing it to be used in a specific clotting assay for Factor VIIa free from interference by Factor VII.
Since the vast majority of FVII in plasma is in the inactive, zymogen form, and since tTF is selectively deficient in promoting conversion of Factor VII to Factor VIIa, tTF has extremely little procoagulant activity towards normal plasma. Since tTF lacks the membrane-anchoring domain of the protein, it lacks the ability to become incorporated into exposed phospholipid surfaces as wild-type apo-TF can. Although the deficiency of tTF in the conversion of FVII to FVIIa was not previously appreciated, its extremely low procoagulant activity when tested with normal plasma has made it appear to be unacceptable as a therapeutic agent to control bleeding in hemophilia.
The essential difference between truncated tissue factor and wild-type tissue factor is that truncated tissue factor is no longer tethered to the phospholipid membrane surface. It is therefore expected that other methods for preparing truncated tissue factor can be used to generate an essentially equivalent soluble form of tissue factor that retains FVIIa cofactor activity while no longer stimulating conversion of Factor VII to Factor VIIa. Methods include chemical and/or enzymatic cleavage of wild-type tissue factor to separate the predicted extracellular domain from the transmembrane region. Recombinant human TF is available from Calbiochem Corporation. Precise positioning of the stop codon following amino acid 219 is believed to not be essential to make functional truncated TF, and other placements of a stop codon near amino acid 219 are predicted to yield an essentially equivalent product with respect to its ability in conjugation with FVIIa to serve as a treatment for bleeding disorders.
Activated Factor VII
Factor VII can be prepared as described by Fair, Blood 62:784-791 (1983). The coding portion of the human Factor VII cDNA sequence reported by Hagen et al., Proc Natl Acad Sci USA 83:2412-2416 (1986) is shown as SEQ ID NO:3, along with the translated amino acid sequence, SEQ ID NO:4. The amino acid sequence from 1 to 60 corresponds to the pre-pro/leader sequence that is removed by the cell prior to secretion. The mature FVII polypeptide chain consists of amino acids 61 to 466. FVII is converted to FVIIa by cleavage of a single peptide bond between arginine-212 and isoleucine-213.
FVII can be converted in vitro to FVIIa by incubation of the purified protein with Factor Xa immobilized on Affi-Gel.TM. 15 beads (Bio-Rad). Conversion can be monitored by SDS-polyacrylamide gel electrophoresis of reduced samples. Free Factor Xa in the FVIIa preparation can be detected with the chromogenic substrate methoxycarbonyl-D- cyclohexylglycyl-glycyl-arginine-p-nitroanilide acetate (Spectrozyme.TM. FXa, American Diagnostica, Greenwich, Conn.) at 0.2 mM final concentration in the presence of 50 mM EDTA.
Recombinant FVIIa can also be purchased from Novo Biolabs (Danbury, Conn.).
Administration of the combination of the tTF and FVIIa
The tTF and FVIIa are administered by infusion in the preferred embodiment, using a pharmaceutically acceptable carrier such as saline or buffered saline. The tTF and FVIIa can also be administered topically either by direct application using a conventional topical base such as petrolatum or a water based gel, or as an aerosol spray.
The tTF is administered in a dosage effective to produce in the plasma an effective level of between 100 ng/ml and 50 .mu.g/ml, or a preferred level of between 1 .mu.g/ml and 10 .mu.g/ml or 60 to 600 .mu.g/kg body weight, when administered systemically; or an effective level of between 10 .mu.g/ml and 50 .mu.g/ml, or a preferred level of between 10 .mu.g/ml and 50 .mu.g/ml, when administered topically.
The FVIIa is administered in a dosage effective to produce in the plasma an effective level of between 20 ng/ml and 10 .mu.g/ml (1.2 to 600 .mu.g/kg), or a preferred level of between 40 ng/ml and 4 .mu.g/ml (2.4 to 240 .mu.g/kg), or a level of between 1 .mu.g/ml and 10 .mu.g/ml FVIIa when administered topically.
In general, one would administer tTF and FVIIa to produce levels of up to 10 .mu.g tTF/ml plasma and between 40 ng and 4 .mu.g FVIIa/ml plasma. For hemophilic patients, one would administer tTF and FVIIa to produce levels of up to 10 .mu.g tTF and between 100 and 300 ng FVIIa/ml. For patients with cirrhosis, one would administer the same amount of tTF but up to 1 .mu.g FVIIa/ml plasma.
Since tTF cannot stimulate conversion of FVII to FVIIa, it should only be functional in conjunction with elevated factor VIIa levels. Therefore, tTF is expected to be an effective hemostatic agent only in association with FVIIa therapy or in individuals who have elevated FVIIa levels for some other reason.
Other conditions that can be treated with this combination include surgical bleeding from the microvasculature, bleeding at skin graft harvest sites, postoperative bleeding, including following orthopedic surgery, brain surgery or brain trauma, bleeding secondary to thrombocytopenia, and platelet dysfunction.
EXAMPLE 1
Safety,of tTF and FVIIa in normal dogs.
Three beagle dogs were treated with either tTF or tTF plus FVIIa.
Dog #5533 was treated with tTF alone, in a dosage of 60 .mu.g tTF/kg body Weight by intravenous bolus infusion. ELISA studies showed 1.23 .mu.g tTF/ml in plasma at time zero. Half-life of tTF was 2.2 hr in this dog.
Dog #5534 was also treated with tTF alone, in a dosage of 41 .mu.g tTF/kg body weight by intravenous bolus infusion. Assuming a blood volume of 60 ml/kg, this should have produced a level of 0.67 .mu.g tTF/ml in the blood. ELISA studies showed 0.60 .mu.g tTF/ml in plasma at time zero. Half-life of tTF was 1.3 hr in this dog.
Dog #5734 was treated with tTF in combination with FVIIa, in a dosage of 41 .mu.g tTF/kg body weight and 6.37 .mu.g Novo recombinant factor VIIa/kg body weight by intravenous bolus infusion. ELISA studies showed 0.51 .mu.g tTF/ml in plasma at time zero. Half-life of tTF was biphasic (1 hr followed by 3.0 hr) in this dog.
The dogs all remained healthy and active. Blood tests of the clotting system indicated no significant decrease in fibrinogen levels or platelet counts and no measurable increase in fibrin degradation products. Prothrombin times and APTT times were normal, as were white blood cell counts, and red blood cell counts. Therefore, administration of either tTF alone, or tTF in conjunction with FVIIa, caused no measurable disseminated intravascular coagulation or other detectable coagulopathy.
A complete necropsy was performed on the animal receiving truncated tissue factor and factor VIIa. No evidence of thrombosis was found in veins, arteries or in the capillaries. There was no evidence on gross and microscopic examination of myocardial infarction or of cerebral infarction (stroke).
EXAMPLE 2
In vitro correction of clotting time of hemophilic plasma with tTF in combination with FVIIa.
A modified prothrombin test (PT) was performed with diluted thromboplastin (since hemophiliacs have normal PT's unless the thromboplastin is diluted) using either normal or congenital factor VIII deficient (Hemophilia A) plasma. Sigma Chemical Co. rabbit brain thromboplastin was diluted 1:500 with TBS/0.1% BSA/rabbit brain cephalin (Sigma Chemical Co., St. Louis, Mo.).
12.times.75 mm glass test tubes were pre-warmed in a 37.degree. C. water bath.
Diluted thromboplastin was added (0.1 ml) and allowed to warm to 37.degree. C. for more than two minutes.
Plasma sample (0.1 ml) was added and allowed to warm to exactly 30 sec.
Pre-warmed 25 mM CaCl.sub. 2 (at 37.degree. C.) was added and the clotting time was determined by the manual tilt-tube method.
The results are shown in FIG. 1a and 1b. FIG. 1a is a graph of dilute thromboplastin clotting time (seconds) for factor VIII-deficient plasma when tTF (1 .mu.g/ml) and varying concentrations of FVIIa (ng/ml) are added (dark triangles) or when varying concentrations of FVIIa alone (ng/ml) are added (dark circles). FIG. 1b is a graph of dilute thromboplastin clotting time (seconds) for normal plasma when tTF (1 .mu.g/ml) and varying concentrations FVIIa (ng/ml) are added (dark triangles) or when varying concentration of FVIIa alone (ng/ml) are added (dark circles). The clotting time of the hemophilic plasma without any added FVIIa or tTF was 88.5 sec which is indicated by the upper dotted horizontal line. The clotting time of normal plasma without added FVIIa or tTF was 53,0 sec which is indicated by the lower dotted horizontal line. Without added tTF, the 88.5 sec clotting time of the hemophilic plasma was reduced to that of normal plasma (53 sec) at 808 ng FVIIa/ml of plasma. With added tTF (at 1 .mu.g/ml), the clotting time of the hemophilic plasma was reduced to that of normal plasma at 36.8 ng FVIIa/ml plasma.
Therefore, in the presence of 1 .mu.g/ml tTF in plasma, correction of the prolonged clotting time of hemophilic plasma was achieved at a level of added FVIIa that was 22-fold lower than in the absence of added tTF. In addition, tTF was not able to correct the prolonged clotting time of hemophilic plasma in the absence of added FVIIa.
EXAMPLE 3
Efficacy of the combination of tTF and FVIIa in the treatment of Hemophilic Dogs.
As described by Brinkhous, et al., Proc Natl Acad Sci USA 82:8752-8756 (1985), Graham, et al., J Exp Med 90:97-111 (1949), and Brinkhous, et al., Ann NY Acad Sci 370:191-204 (1981), a colony of hemophilic dogs has been developed at the University of North Carolina at Chapel Hill. Dogs have hemophilia A. A test (secondary cuticle bleeding time) is used to measure bleeding tendency.
A modified toenail bleeding time (BT) is used to test the hemostatic effectiveness of infused preparations. The paw of the front leg is warmed by placing it in isotonic saline at 37.degree. C. and a toenail is trimmed to expose only the distal matrix. The bleeding nail is placed in isotonic saline at 37.degree. C. and the time until cessation of bleeding recorded as the primary BT. At 2 to 4 hours, the site is shaved to remove the clot and as little nail matrix as possible. The paw is again placed in saline at 37.degree. C. A discrete stream of extruding blood is visible. With hemophilic dogs in the absence of treatment, bleeding typically continues for 30 min or longer. This time to cessation of bleeding is recorded as a secondary BT. For normal dogs, the primary BT is two to five minutes and the secondary BT is less than five minutes. For hemophilic dogs the primary BT is similar to that of normal dogs while secondary BT is greater than 15 minutes.
Dog #V02 was administered a low dose of FVIIa, 6 .mu.g FVIIa/kg body weight, which was designed to provide only a weak hemostatic effect. After 15 min equilibrium, secondary cuticle bleeding time was measured at 2 min 30 Sec, which spontaneously rebled for 5 min 15 sec. Rebleeding challenge (wipe off clot with gauze): 9 min 20 sec bleeding time, which again spontaneously rebled for 15 min, at which time the nail was cauterized to prevent further bleeding. It was difficult to stop bleeding and oozing from the phlebotomy sites in this dog, which continued after FVIIa administration.
The results indicate that this dosage of FVIIa had a very weak hemostatic effect.
The dog was then administered 42 .mu.g tTF/kg body weight. After 15 min equilibration, secondary cuticle bleeding time was measured at 50 sec, which did not spontaneously rebleed. This was dramatically shorter than when the animal had received FVIIa alone. Wiping the clot off with gauze to provoke rebleeding caused rebleeding for only 35 sec, and no subsequent rebleeding was observed. Oozing from two phlebotomy sites in forepaw veins also stopped following infusion of tTF.
The results indicated that tTF in combination with low dose FVIIa has an excellent hemostatic effect.
The same dog was administered 42 .mu.g tTF/kg body weight, without FVIIa, two days later (since the half-lives of both tTF and FVIIa are about 2 hr, this was more than sufficient to ensure clearance of either substance from the plasma). After 15 minutes equilibration, the secondary cuticle bleeding time was greater than 15 minutes and had to be stopped by cauterization.
The results indicated that tTF alone had no measurable hemostatic effect.
The dog was then administered 6 .mu.g FVIIa/kg body weight. After 15 minutes equilibration, secondary cuticle bleeding time was measured at 3 minutes 15 seconds, which did not spontaneously rebleed. Wiping the clot off with gauze caused rebleeding for 3 minutes, and no subsequent rebleeding was observed.
The results again demonstrate that tTF in combination with low dose FVIIa has a very good hemostatic effect.
Modifications and variations of the present invention, a method and compositions for the treatment of excessive bleeding, will be obvious from the foregoing detailed description and are intended to come within the scope of the appended claims.
Claims
We claim:
1. A method for treating a patient for excessive bleeding occurring at a site, comprising the step of: simultaneously administering an effective amount of a truncated tissue factor protein and an effective amount of Factor VIIa to a patient to effect clotting of said patient's blood at said site and subsequent reduction of said excessive bleeding, said truncated tissue factor protein having an amino acid sequence beginning at position 1 and terminating near position 219 of SEQ ID NO:2, said truncated tissue factor protein differing from that of native tissue factor in that transmembrane amino acids selected from the membrane spanning domain of native tissue factor which would be sufficient to bind said truncated tissue factor protein to phospholipid membranes are lacking from said truncated tissue factor protein so that said truncated tissue factor protein does not bind to phospholipid membranes, said truncated tissue factor protein further characterized in that it is soluble and that it fails to convert Factor VII to Factor VIIa yet retains catalytic activity in cleaving Factor X in the presence of Factor VIIa.
2. The method of claim 1, wherein said effective amount of said truncated tissue factor protein is an amount sufficient to produce a level of from about 100 nanograms to about 50 micrograms said truncated tissue factor protein per milliliter of plasma and said effective amount of said Factor VIIa is an amount sufficient to produce a level of from about 20 nanograms to about 10 micrograms Factor VIIa per milliliter of plasma.
3. The method of claim 2, wherein said truncated tissue factor protein is in an amount sufficient to produce a level of from about 1 microgram to about 10 micrograms truncated tissue factor protein per milliliter of plasma.
4. A method according to claim 3, wherein said Factor VIIa is administered to produce a level of between about 40 nanograms and 4 micrograms Factor VIIa per milliliter of plasma.
5. A method for treating a patient to control bleeding according to claim 1 wherein said truncated tissue factor protein and said Factor VIIa are administered topically to a wound site.
6. A method for treating a patient to control bleeding according to claim 5 wherein a sufficient amount of said truncated tissue factor protein is administered to produce a local concentration in said wound site of from about 10 to about 50 micrograms truncated tissue factor protein per milliliter of plasma and a sufficient amount of said Factor VIIa is administered to produce a local concentration in said wound site of from about 1 to about 10 micrograms Factor VIIa per milliliter of plasma.
7. A method for treating a patient for excessive bleeding occurring at a site, comprising the step of: sequentially administering an effective amount of a truncated tissue factor protein and an effective amount of Factor VIIa to a patient to effect clotting of said patient's blood at said site and subsequent reduction of said excessive bleeding, said truncated tissue factor protein having an amino acid sequence beginning at position 1 and terminating near position 219 of SEQ ID NO:2, said truncated tissue factor protein differing from that of native tissue factor protein in that transmembrane amino acids selected from the membrane spanning domain of native tissue factor protein which would be sufficient to bind said truncated tissue factor protein to phospholipid membranes are lacking from said truncated tissue factor protein so that said truncated tissue factor protein does not bind to phospholipid membranes, said truncated tissue factor protein further characterized in that it is soluble and that it fails to convert Factor VII to Factor VIIa yet retains catalytic activity in cleaving Factor X in the presence of Factor VIIa.
8. The method of claim 7, wherein said effective amount of said truncated tissue factor protein is an amount sufficient to produce a level of from about 100 nanograms to about 50 micrograms said truncated tissue factor protein per milliliter of plasma and said effective amount of said factor protein VIIa is an amount sufficient to produce a level of from about 20 nanograms to about 10 micrograms Factor VIIa per milliliter of plasma.
9. The method of claim 8, wherein said truncated tissue factor protein is added to produce a level of from about 1 microgram to about 10 micrograms truncated tissue factor protein per milliliter of plasma.
10. The method of claim 9, wherein said Factor VIIa is administered to produce a level of between about 40 nanograms and 4 micrograms Factor VIIa per milliliter of plasma.
11. A method for treating a patient to control bleeding according to claim 7 wherein said truncated tissue factor protein and said Factor VIIa are administered topically to a wound site.
12. A method for treating a patient to control bleeding according to claim 11 wherein a sufficient amount of said truncated tissue factor protein is administered to produce a local concentration in said wound site of from about 10 to about 50 micrograms truncated tissue factor protein per milliliter of plasma and a sufficient amount of said Factor VIIa is administered to produce a local concentration in said wound site of from about 1 to about 10 micrograms Factor VIIa per milliliter of plasma.
13. A pharmaceutical composition for treating excessive bleeding comprising a truncated tissue factor protein having an amino acid sequence beginning at position 1 and terminating near position 219 of SEQ ID NO:2, said truncated tissue factor protein differing from that of native tissue factor protein in that transmembrane amino acids selected from the membrane spanning domain of native tissue factor protein which would be sufficient to bind said truncated tissue factor protein to phospholipid membranes are lacking from said truncated tissue factor protein protein so that said truncated tissue factor protein does not bind to phospholipid membranes, said truncated tissue factor protein further characterized in that is soluble and that it fails to convert Factor VII to Factor VIIa yet retains catalytic activity in cleaving Factor X in the presence of Factor VIIa, and Factor VIIa.
14. The composition of claim 13, further comprising a pharmaceutically acceptable carrier for systemic administration.
15. The composition of claim 13, further comprising a pharmaceutically acceptable carrier for topical administration.
16. The composition of claim 15, wherein said composition comprises about 10 nanograms to about 50 micrograms of said truncated tissue factor protein per milliliter of said carrier and from about 1 to about 10 micrograms Factor VIIa per milliliter of said carrier.
17. A pharmaceutical composition according to claim 16 wherein said truncated tissue factor protein is present in a concentration of from about 10 to about 50 micrograms per milliliter of said carrier.
18. A method for treating a patient for excessive bleeding occurring at a site, comprising the step of: simultaneously administering an effective amount of a truncated tissue factor protein and an effective amount of Factor VIIa to said patient to effect clotting of said patient's blood at said site and subsequent reduction of said excessive bleeding, said truncated tissue factor protein further characterized in that it does not bind to phospholipid membranes, that it is soluble and that it fails to convert Factor VII to Factor VIIa yet retains catalytic activity in cleaving Factor X in the presence of Factor VIIa.
19. A method for treating a patient for excessive bleeding occurring at a site, comprising the step of: sequentially administering an effective amount of a truncated tissue factor protein and an effective amount of Factor VIIa to said patient to effect clotting of said patient's blood at said site and subsequent reduction of said excessive bleeding, said truncated tissue factor protein further characterized in that it does not bind to phospholipid membranes, that it is soluble and that it fails to convert Factor VII to Factor VIIa yet retains catalytic activity in cleaving Factor X in the presence of Factor VIIa.
20. A pharmaceutical composition for treating excessive bleeding comprising a truncated tissue factor protein, said truncated tissue factor protein further characterized in that it does not bind to phospholipid membranes, that it is soluble and that it fails to convert Factor VII to Factor VIIa yet retains catalytic activity in cleaving Factor X in the presence of Factor VIIa, and Factor VIIa.
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