Use of recombinant factor VIIa (NovoSeven) in patients with Glanzmann thrombasthenia

Maternal Coagulation Disorders and Postpartum Hemorrhage

Coagulation disorders are rare causes of postpartum hemorrhage. Disturbances in coagulation should be suspected in patients with a family history of coagulopathy, those with a personal history of heavy menstrual bleeding, and those with persistent bleeding despite correction of other causes. The coagulopathic conditions discussed include disseminated intravascular coagulation, platelet disorders, and disturbances of coagulation factors. These should not be overlooked in the evaluation of obstetric hemorrhage, as diagnosis and appropriate treatment may prevent severe maternal morbidity and mortality.

Indication for allogeneic stem cell transplantation in Glanzmann’s thrombasthenia

Glanzmann’s thrombasthenia (GT) is an autosomal recessive disorder characterized by a lack of thrombocyte aggregation due to the absence of thrombocyte glycoproteins IIb and αIIbβ3. The role of haematopoietic stem cell transplantation (HSCT) in GT remains controversial. However, HSCT offers the only curative approach for patients with a severe clinical phenotype.

In this review, we will discuss the limitation of current status evidence and the specific risk of GT, in particular the alloimmunization and refractoriness to thrombocyte infusions. 19 successful HSCT in 18 GT type I patients have been reported. Mean age at transplantation was 5 years. All patients are still alive. The majority received sibling bone marrow transplant with busulfan and cyclophosphamid conditioning. GvHD incidence was within the normal range, but 10 patients showed alloimmunization of thrombocytes. Median follow up is 25 months.

Management of Pregnancy in a Chilean Patient with Congenital Deficiency of Factor VII and Glanzmann's Thrombasthenia Variant

Patients with inherited bleeding disorders are rare in obstetric practice but present with prolonged bleeding even after minor invasive procedures. They require a combined approach with obstetric and hematological management of each case, including the neonatal management of a possibly affected fetus. We present the case of a pregnancy in a patient with combined Factor VII deficiency and Glanzmann's thrombasthenia, the successful obstetric and hematological management of the case, and a review of the literature.

Successful unrelated donor cord blood transplantation for Glanzmann's thrombasthenia

GT, a rare disorder of platelet function, can lead to life-threatening bleeding, particularly following the development of antiplatelet antibodies. Curative therapy includes HCT but previous reports are limited predominantly to matched siblings and have excluded CBT. Delayed or non-engraftment of platelets because of antiplatelet antibodies might be particularly concerning after CBT for GT. Here, we report two successful unrelated cord blood transplants for GT. Recurrent life-threatening bleeding was the primary indication for HCT, with one patient developing antiplatelet antibodies pre-HCT. Bleeding risks associated with delivery of the conditioning regimen and the toxicity that follows should be carefully considered, including tunneled central venous line catheter placement, inclusion of B cell-specific therapy to potentially decrease antiplatelet antibody production, and targeted busulfan dosing. This is the first report of successful unrelated cord blood HCT for GT and indicates that modifications to supportive care can improve the safety of this potentially curative therapy for patients with severe, life-threatening disease manifestations.

Molecular intercommunication between the complement and coagulation systems

The complement system as well as the coagulation system has fundamental clinical implications in the context of life-threatening tissue injury and inflammation. Associations between both cascades have been proposed, but the precise molecular mechanisms remain unknown. The current study reports multiple links for various factors of the coagulation and fibrinolysis cascades with the central complement components C3 and C5 in vitro and ex vivo. Thrombin, human coagulation factors (F) XIa, Xa, and IXa, and plasmin were all found to effectively cleave C3 and C5. Mass spectrometric analyses identified the cleavage products as C3a and C5a, displaying identical molecular weights as the native anaphylatoxins C3a and C5a. Cleavage products also exhibited robust chemoattraction of human mast cells and neutrophils, respectively. Enzymatic activity for C3 cleavage by the investigated clotting and fibrinolysis factors is defined in the following order: FXa > plasmin > thrombin > FIXa > FXIa > control. Furthermore, FXa-induced cleavage of C3 was significantly suppressed in the presence of the selective FXa inhibitors fondaparinux and enoxaparin in a concentration-dependent manner. Addition of FXa to human serum or plasma activated complement ex vivo, represented by the generation of C3a, C5a, and the terminal complement complex, and decreased complement hemolytic serum activity that defines exact serum concentration that results in complement-mediated lysis of 50% of sensitized sheep erythrocytes. Furthermore, in plasma from patients with multiple injuries (n = 12), a very early appearance and correlation of coagulation (thrombin-antithrombin complexes) and the complement activation product C5a was found. The present data suggest that coagulation/fibrinolysis proteases may act as natural C3 and C5 convertases, generating biologically active anaphylatoxins, linking both cascades via multiple direct interactions in terms of a complex serine protease system.

Glanzmann thrombasthenia: an update

Glanzmann thrombasthenia (GT) is a rare autosomal recessive disorder characterized by qualitative or quantitative abnormalities of the platelet membrane glycoprotein (GP) IIb/IIIa. Physiologically, this platelet receptor normally binds several adhesive plasma proteins, and this facilitates attachment and aggregation of platelets to ensure thrombus formation at sites of vascular injury. The lack of resultant platelet aggregation in GT leads to mucocutaneous bleeding whose manifestation may be clinically variable, ranging from easy bruising to severe and potentially life-threatening hemorrhages. In this review we discuss the main characteristics of GT, focusing on molecular defects, diagnostic evaluation and treatment strategies.

Use of recombinant activated factor VII in patients without hemophilia: a meta-analysis of randomized control trials

CONTEXT

Benefits of recombinant activated factor VII (rFVIIa) in hemorrhage may be lost because of thromboembolic events (TAE).

METHOD

MEDLINE, EMBASE, BIOSIS, CINAHL, Science Citation Index Expanded, clinicaltrials.gov were searched for placebo controlled trials of rFVIIa in patients without hemophilia. Reports of 22 randomized controlled trials were selected for analysis. Results were pooled using random effects models to calculate the odds ratios (OR) with 95% confidence interval (CI). Subgroup analyses were predetermined.

RESULTS

Among 3184 participants, 478 (15.0%) died and 249 (7.8%) had TAE. Additional blood transfusion was required in 517 (41.2%) of 1256 subjects. Patients receiving rFVIIa were less likely to need additional blood transfusions (OR, 0.54; 95% CI, 0.34-0.86) than patients receiving placebo. Mortality was not increased but may be reduced (OR, 0.88; 95% CI, 0.71-1.09). Reduction in mortality was more likely if rFVIIa was given therapeutically (OR, 0.87; 95% CI, 0.70-1.09) rather than prophylactically (OR, 1.00; 95% CI, 0.37-2.68). Differences in the pooled analysis of TAE were not statistically significant (OR, 1.17; 95% CI, 0.87-1.58) but the incidence of arterial TAE was likely higher in patients receiving rFVIIa (OR, 1.50; 95% CI, 0.93-2.41) although no differences were seen with respect to venous TAE (OR, 0.76; 95% CI, 0.49-1.15).

CONCLUSIONS

Use of rFVIIa reduces the need for blood transfusion and it may reduce mortality, especially if the dose of rFVIIa is limited to therapeutic doses of 90 mug/kg. It does not increase the risk of venous thrombosis but it may increase the risk of arterial thrombosis.

Stem cell transplantation for children with Glanzmann thrombasthenia

Glanzmann thrombasthenia (GT) is a rare autosomal recessive platelet function disorder. Stem cell transplantation (SCT) is curative, but it is only indicated in selected patients with a severe clinical phenotype or who develop anti-platelet antibodies. SCT have previously been limited to full intensity myeloablative conditioning regimens. This study details the successful outcome of SCT in five consecutive patients with GT, three of whom received reduced intensity conditioning (RIC) with stem cells from non-sibling donors. This is the first time RIC SCT has been reported in GT, and offers the possibility of curative therapy with reduced late effects.

The use of recombinant activated factor VII in obstetric and gynaecological haemorrhage

Recombinant activated factor VII (rFVIIa) was originally developed for the treatment of bleeding in patients with haemophilia A or B and inhibitors. Over the past ten years, it has been successfully used to prevent or control bleeding in several other nonhaemophilic bleeding conditions. Among the newer 'off-label' clinical applications of rFVIIa, there is increasing evidence of its effectiveness in treating obstetric and gynaecological bleeding unresponsive to conventional therapy. The existing literature on the use of rFVIIa in obstetrics and gynaecology is summarised in this review. Although supported by few and uncontrolled studies, on the whole, the published data suggest a potential role of rFVIIa in the management of obstetric and gynaecological intractable bleeding. However, further evidence is needed to improve the assessment of its optimal dose, effectiveness and safety in such conditions.

Use of recombinant activated factor VII to control bleeding in a young child with qualitative platelet disorder: a case report

Defects of platelet adhesion, aggregation, secretion, or procoagulant activities can lead to bleeding diathesis of variable severity. We used recombinant activated factor VII (rFVIIa) in the treatment of uncontrolled epistaxis in a patient with a qualitative platelet disorder. We aimed to assess the efficacy of a single rFVIIa dose (100 microg/kg) in the control of mild and severe refractory epistaxis, and evaluate the influence of rFVIIa on markers of platelet adhesion and aggregation during a period of hematological stability (i.e. non-bleeding, no medication). The efficacy study showed mild episodes of epistaxis could be successfully managed using a single rFVIIa (100 microg/kg) dose; however, severe bleedings were not well controlled, and platelet transfusion was required to achieve hemostasis. Hematological investigations showed ADP-induced and collagen-induced platelet aggregation increases from 20 to 34% and 16 to 30%, respectively, following rFVIIa administration. There were no differences between pre-dose and post-dose concentrations of membrane glycoproteins. rFVIIa may therefore induce platelet aggregation by activating a glycoprotein-independent aggregation pathway. rFVIIa may have a role in managing mild bleeding episodes not controlled using conventional measures in patients with a qualitative platelet disorder. Further research is needed to determine the mechanism of action, efficacy, and safety of rFVIIa in this population.

Mechanism of Action of Recombinant Activated Factor VII: An Update

Bleeding episodes in patients with hemophilia and inhibitors must be managed using agents that are hemostatically active in the absence of factor VIII or IX. Activated prothrombin complex concentrates have long been used in this context. However, the search for safer and more effective agents has led to the development of recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark). This paper presents an update on the mechanism of action of rFVIIa, and describes how pharmacologic doses of this agent enhance thrombin production and thus contribute to the development of a stable, lysis-resistant fibrin plug at the site of vessel damage. This mechanism explains the reported efficacy of rFVIIa in a range of clinical situations characterized by impaired thrombin generation.

Sustained engraftment post bone marrow transplant despite anti-platelet antibodies in Glanzmann thrombasthenia

BACKGROUND

Patients with Glanzmann thrombasthenia (GT) have normal platelet counts but abnormal platelet aggregation and carry the risk of life-threatening bleeding. We report three patients who received bone marrow transplantation (BMT) for type I GT and discuss the risk and management of anti-platelet antibodies.

PATIENTS AND RESULTS

Diagnosis of GT was made through abnormal platelet aggregation studies or the absence of GPIIb/IIIa by flow cytometry. All patients had severe bleeding requiring multiple red blood cell transfusions. One patient received an unrelated donor transplant and two received matched sibling donor transplants following conditioning therapy with busulfan, cyclophosphamide, and fludarabine. Two patients developed an anti-platelet antibody, treated in one with intravenous immune globulin (IVIG). Engraftment of white blood cells and platelets was achieved on day +13 to +14 and +17 to +25, respectively. Complete donor chimerism and GPIIb/IIIa+ platelets are sustained at +22 to +30 months post transplant.

CONCLUSIONS

In summary, patients with GT and history of severe hemorrhage can be cured with BMT, but the presence of anti-platelet antibodies should be sought and platelet transfusions minimized prior to transplant. IVIG may be helpful in cases of refractory immune thrombocytopenia related to anti-platelet antibodies. Improvement in transplant-related complications with current transplant regimens allows consideration of BMT for life-threatening non-malignant disorders such as GT.

Recombinant coagulation factor VIIa--a novel haemostatic agent in scoliosis surgery?

Spinal fusion surgery in children and adolescents with idiopathic scoliosis is often associated with severe haemorrhage. Recombinant coagulation factor VIIa (rFVIIa) has previously been shown to be an effective haemostatic treatment for severe bleeding associated with a variety of coagulopathic and non-coagulopathic indications. The aim of this retrospective study was to assess the safety and haemostatic efficacy of rFVIIa in a series of 26 consecutive adolescent patients with scoliosis (22 females; mean age 16.6 years) undergoing correctional surgery. A second series of 26 consecutive patients (20 females; mean age 16.2 years) who received standard therapy during surgery, represented historical controls. Blood loss, transfusion requirements, duration of surgery, and peri-operative measurements of coagulation parameters were compared between the two groups. Intra-operative and combined intra-operative and post-operative blood losses were significantly smaller in the rFVIIa-treatment group than in the historical controls (P=0.003 and 0.032, respectively); rFVIIa-treated patients also demonstrated significantly reduced blood loss per vertebral segment fused (P=0.032) and per hour of surgery (P<0.001). Intra-operative requirements for packed red blood cells were also significantly lower in the treatment group (P=0.042). Patients in the treatment group demonstrated rapid and maintained reduction of prothrombin time and international normalised ratio; values among rFVIIa-treated patients remained significantly lower than those in the control group at all time points evaluated (P<0.001). There were no deaths and no adverse events. These results suggest that rFVIIa is a safe and effective haemostatic agent for use during spinal fusion surgery in adolescent patients with idiopathic scoliosis; however, further research and randomised, placebo-controlled trials are needed to confirm these findings.

Pregnancy in mother with Glanzmann's thrombasthenia and isoantibody against GPIIb–IIIa: Is there a foetal risk?

Glanzmann's thrombasthenia (GT) is a rare autosomal recessive platelet disorder caused by qualitative or quantitative abnormalities of a platelet glycoprotein complex (GPIIb-IIIa) leading to excessive bleeding. Platelet transfusions are the first-line therapy for severe or persistent bleeding and surgery. Isoantibody against GPIIb-IIIa complexes present on normal platelets can be observed in Glanzmann's thrombasthenia type I patients after platelet transfusion possibly leading to platelet transfusion refractoriness. Pregnancy in Glanzmann's thrombasthenia type I women is rare, and severe bleeding can be observed in the peripartum or late postpartum period. Moreover, pregnancy can contribute to the maternal isoimmunization by the passage of the foetal cells into the maternal circulation. The transplacental passage of the maternal isoantibodies can induce moderate to severe foetal thrombocytopenia. We discuss here the case of in utero death at 31 weeks of gestation due to intracranial haemorrhage in an immunized mother and review the literature. Presence of isoantibody prior to gestation or detected during the index pregnancy must be taken into account in evaluating risk for the mother and the foetus.

Utilización del factor VII activado en hemorragias agudas graves

Acute hemorrhage is a sometimes serious complication that may arise in patients admitted to the intensive care unit with coagulopathy. The usual therapy is transfusion of blood components: fresh frozen plasma, platelets, fibrinogen, red cell concentrate and vitamin K. Tolerance or response can sometimes be poor. We present three patients aged 18 months, 4.5 and 10 years who suffered an acute episode of severe, life-threatening hemorrhage in the course of meningococcal sepsis (gastric hemorrhage), myelomonocytic leukemia (during splenectomy) and in the postoperative period after cardiovascular surgery. Traditional therapy was ineffective and activated factor VII was administered at doses of 50-70 microg/kg, with rapid control of bleeding.

Recombinant factor VIIa enhances platelet adhesion and activation under flow conditions at normal and reduced platelet count

BACKGROUND

Recombinant factor VIIa (rFVIIa), which was developed for treatment of inhibitor-complicated hemophilia, appears suitable as prohemostatic agent in other clinical disorders including patients with thrombocytopenia. It is generally accepted that rFVIIa functions by enhancement of thrombin generation at the site of injury. It is, however, unknown if and how this affects platelet adhesion and aggregation.

OBJECTIVES

To determine the effect of rFVIIa-mediated thrombin generation on platelet adhesion and aggregation under flow conditions at normal and reduced platelet counts.

METHODS

Washed platelets and red cells were combined to obtain plasma-free blood with different platelet counts. The reconstituted blood was perfused over a collagen- or fibrinogen-coated surface in the absence or presence of a thrombin generating system consisting of purified coagulation factors rFVIIa, factor (F)X and prothrombin.

RESULTS

Addition of coagulation factors rFVIIa, FX and prothrombin to washed platelets and red cells enhanced platelet adhesion and aggregation to collagen and adhesion and spreading to fibrinogen at normal platelet count and at platelet numbers as low as 10 000 microL(-1). rFVIIa-mediated thrombin generation enhanced the activation state of platelets as measured by intracellular calcium fluxes, and enhanced the exposure of procoagulant phospholipids as measured by annexin A5 binding.

CONCLUSIONS

Taken together, increased platelet adhesion and aggregation by rFVIIa-mediated thrombin formation may explain the therapeutic effects of rFVIIa in thrombocytopenic conditions and in patients with a normal platelet count by (i) enhancement of primary hemostasis and (ii) enhancement of procoagulant surface leading to elevated fibrin formation.

An in vitro evaluation of standard rotational thromboelastography in monitoring of effects of recombinant factor VIIa on coagulopathy induced by hydroxy ethyl starch

Background

Rotational thromboelastography (ROTEG) has been proposed as a monitoring tool that can be used to monitor treatment of hemophilia with recombinant factor VIIa (rFVIIa). In these studies special non-standard reagents were used as activators of the coagulation. The aim of this study was to evaluate if standard ROTEG analysis could be used for monitoring of effects of recombinant factor VIIa (rFVIIa) on Hydroxy Ethyl Starch-induced dilutional coagulopathy.

Methods

The study was performed in vitro on healthy volunteers. Prothrombin time (PT) and ROTEG analysis were performed after dilution with 33% hydroxy ethyl starch and also after addition of rFVIIa to the diluted blood.

Results

PT was impaired with INR changing from 0.9 before dilution to 1.2 after dilution while addition of rFVIIa to diluted blood lead to an overcorrection of the PT to an International Normalized Ratio (INR) value of 0.6 (p = 0.01). ROTEG activated with the contact activator ellagic acid was impaired by hemodilution (p = 0.01) while addition of rFVIIa had no further effects. ROTEG activated with tissue factor (TF) was also impaired by hemodilution (p = 0.01) while addition of rFVIIa lead to further impairment of the coagulation (p = 0.01).

Conclusions

The parameters affected in the ROTEG analysis were Clot Formation Time and Amplitude after 15 minutes while the Clotting Time was unaffected. We believe these effects to be due to methodological problems when using standard activators of the coagulation in the ROTEG analysis in combination with rFVIIa.

The use of recombinant factor VIla in a primigravida with Glanzmann's thrombasthenia during delivery

Glanzmann's thrombasthenia is an inherited hemorrhagic disorder characterized by a severe reduction in, or absence of, platelet aggregation in response to multiple physiologic agonists due to qualitative or quantitative abnormalities of platelet glycoprotein IIb-IIIa. Glanzmann's thrombasthenia is characterized by potentially major mucocutaneous bleeding and prolonged bleeding time. Platelet counts, platelet morphology, prothrombin, and activated thromboplastin times are all within normal ranges in patients with Glanzmann's thrombasthenia. Pregnancy and delivery are rare in Glanzmann thrombasthenia patients and have been associated with immediate postpartum hemorrhage. We describe the peripartum management of a 31-year-old primipara with Glanzmann's thrombasthenia who underwent spontaneous vaginal delivery. Four units of single-donor platelets, two units of packed red blood cells, 36 microg/kg recombinant human coagulation Factor VIIa (rFVIIa) were given during peripartum management.

Myocardial infarction following recombinant activated factor VII in a patient with type 2A von Willebrand disease

We describe a 50-year-old man with von Willebrand disease type 2A who suffers from angiodysplasia and has required many transfusions for gastro-intestinal haemorrhage. Various investigative modalities have not demonstrated a single source for this. Following a case report of successful use of recombinant activated factor VII (NovoSeven; Novo Nordisk, Copenhagen, Denmark), the patient was treated with it but suffered a large myocardial infarct. As the patient has risk factors for atherosclerotic disease, we presume the recombinant activated factor VII promoted coagulation at a pre-existing atherosclerotic lesion.

Novel therapeutic approach for hemophilia using gene delivery of an engineered secreted activated Factor VII

Hemophilia is a bleeding disorder caused by mutations in the genes encoding coagulation Factor VIII (FVIII) or FIX. Current treatment is through intravenous infusion of the missing protein. The major complication of treatment is the development of neutralizing Ab's to the clotting factor. Infusion of recombinant activated human Factor VII (rhFVIIa), driving procoagulant reactions independently of human FVIII (hFVIII) or hFIX, has been successful in such patients and could in theory provide hemostasis in all hemophilia patients. However, its high cost and short half-life have limited its use. Here, we report a novel treatment strategy with a recombinant adeno-associated virus vector delivering a modified FVII transgene that can be intracellularly processed and secreted as activated FVII (FVIIa). We show long-term expression, as well as phenotypic correction of hemophilia B mice following gene transfer of the murine FVIIa homolog, with no evidence of thrombotic complications at these doses. These data hold promise for a potential treatment for hemophilia and other bleeding disorders.

Recombinant factor VIIa restores aggregation of αIIbβ3-deficient platelets via tissue factor–independent fibrin generation

Recombinant factor VIIa (rFVIIa) is a safe and effective prohemostatic drug for patients with Glanzmann thrombasthenia (GT). However, the mechanism of action of rFVIIa in these patients is still unclear. Although patients with GT are characterized by a complete absence of platelet aggregation to a variety of agonists, it has been shown that GT platelets are able to form aggregates, provided polymerizing fibrin is present. We studied the effect of rFVIIa-mediated fibrin formation on aggregation of αIIbβ3-deficient platelets. When washed platelets from GT patients or platelets from healthy volunteers treated with an arginyl-glycyl-aspartyl–containing peptide were activated with collagen in the presence of rFVIIa and purified coagulation factors X, II, and fibrinogen, complete aggregation occurred after a lag phase. Fibrin generation proceeded via rFVIIa-mediated thrombin generation on the activated platelet surface independently of tissue factor. Electron microscopic analysis of αIIbβ3-independent platelet aggregates showed a densely packed structure suggestive of a true platelet-fibrin interaction and not via trapping of platelets into a fibrin network. Also, rFVIIa-mediated αIIbβ3-independent aggregation was demonstrated under conditions of flow using a collagen-coated surface. In conclusion, the efficacy of rFVIIa in GT patients might be explained by induction of αIIbβ3-independent platelet aggregation, which compensates the lack of αIIbβ3-dependent aggregation.

Thrombasthénie de Glanzmann et grossesse : à propos d’un cas, revue de la littérature

Glanzmann's thrombasthenia is a thrombopathy due to a qualitative or quantitative abnormality of glycoproteins GP IIb-IIIa. Pregnancy is uncommon and dangerous. Delivery often results in important haemorrhage, which is treated with HLA compatible platelet and packed red blood cells transfusions. Platelet transfusion may produce antibody that render transfusions ineffective. Newborn thrombocytopenia is occasionally severe, but is always transitory. Caesarean section has no proven advantage. We report a case with caesarean, which was successfully managed by platelet transfusion over seven peripartum days, with no adverse event. Literature is discussed.

Reversal of the International Normalized Ratio with recombinant activated factor VII in central nervous system bleeding during warfarin thromboprophylaxis: clinical and biochemical aspects

Major bleeding is a frequent and hazardous complication associated with thromboprophylaxis using vitamin-K antagonists (VKA). Suggested regimens for control of highly elevated International Normalized Ratio (INR) and hemorrhagic events during VKA treatment include administration of vitamin K, infusion of fresh frozen plasma (FFP) or a prothrombin complex concentrate (PCC). In contrast, this communication present the first report on the efficacious use of recombinant factor VIIa (rFVIIa) as additional therapy in seven patients presenting with central nervous system (CNS) bleeding emergencies. Pre-treatment INRs ranged from 1.7 to 6.6, and 10 min after a single dose of rFVIIa (10-40 microg/kg) all INRs were </= 1.5. Six patients underwent drainage of the CNS hematoma and all patients survived. No untoward biochemical signs of coagulation activation were detected and no incidence of thromboembolism was observed. In ex-vivo experimental studies, profiles of continuous whole blood clot formation were evaluated by thrombelastography in 25 patients on VKA treatment (INR 1.7-4.3), demonstrating a significantly prolonged initiation phase and diminished propagation of clot formation. Ex-vivo supplementation with rFVIIa to blood of six patients returned a distinct reduction of the prolonged initiation but variable changes in the maximum velocity of clot formation. The ex-vivo experiments and our clinical data support recent suggestions that rFVIIa might substitute for infusion of FFP or PCC in acute reversal of VKA treatment.

Recombinant activated factor VII for the rapid correction of coagulopathy in nonhemophilic neurosurgical patients

OBJECTIVE

Coagulopathy is a significant contraindication for neurosurgery. Unfortunately, many coagulopathic patients require urgent neurosurgical intervention. Standard use of blood products, including fresh-frozen plasma or prothrombin complexes, to correct the coagulopathy often leads to significant delays in treatment. Recombinant activated factor VII (rFVIIa) is a medication originally designed to treat bleeding in hemophiliacs but also seems to correct a wide variety of coagulopathies rapidly and safely in nonhemophilic patients.

METHODS

The medical records of nine patients with coagulopathy requiring urgent neurosurgical intervention were reviewed retrospectively. Each patient was given a dose ranging from 40 to 90 microg/kg of rFVIIa before undergoing surgery. Pre-rFVIIa coagulation and post-rFVIIa coagulation parameters were obtained. Once correction of the coagulopathy was verified, each patient underwent the appropriate neurosurgical procedure.

RESULTS

The average age of the patients was 40.9 years; six were women. The causes of the coagulopathy included anticoagulant medication, liver dysfunction, and dilutional coagulopathy after traumatic hemorrhage. Neurosurgical indications included intraparenchymal/intraventricular hemorrhage, hydrocephalus, diffuse cerebral edema, and epidural hematoma. Post-rFVIIa coagulation parameters obtained as early as 20 minutes after infusion of the medication showed normalization of values. There were no procedural or operative complications and no postoperative hemorrhagic complications. No associated thromboembolic or other complications with the use of rFVIIa were observed.

CONCLUSION

The use of rFVIIa for the urgent surgical treatment of coagulopathic patients is quite promising. Further studies, including randomized, prospective trials using rFVIIa to address issues such as optimal dosing, efficacy, surgical indications, cost-effectiveness, morbidity, and mortality are needed.

Novel applications of recombinant factor VIIa for the management of pediatric coagulopathic diseases

Recombinant factor VIIa (rFVIIa) was envisioned for the treatment of bleeding in hemophilia patients with inhibitors. In response to tissue factor expressed upon vessel wall injury, rFVIIa amplifies the thrombin burst primarily on membrane surfaces, including activated platelets. Because it is functional at a key point in the clotting cascade, rFVIIa shows promise as a therapeutic option for various bleeding situations. The prothrombin time (PT) is often used as a surrogate to monitor rFVIIa therapy. Using laboratory and clinical measures of outcome, the use of rVIIa as a therapeutic option in treating several different pediatric coagulopathic conditions is described.

The use of recombinant factor VIIa in children with inherited platelet function disorders

Inherited deficiencies of platelet surface glycoproteins such as Glanzmann's thrombasthenia (GT) or Bernard-Soulier syndrome (BSS) can lead to a severe bleeding diathesis. In the past, bleeding episodes in these patients have often required platelet transfusion to secure haemostasis but recently a number of patient reports have suggested that recombinant factor VIIa (rVIIa) may also be effective. We have used rVIIa on 33 occasions in seven children with inherited platelet function disorders over a 2-year period: five had GT, one had BSS and one had storage pool disease with a severe phenotype. Bleeding ceased with rVIIa alone in 10 of 28 acute bleeding episodes, but recurred in two of these. The two features that predicted response to rVIIa were the severity of the bleeding and the delay from the onset of bleeding to treatment. Five episodes of planned surgical intervention were treated successfully with rVIIa. Eighteen out of the 28 acute episodes and none of the planned surgical episodes required blood product support. We have found variable efficacy of rVIIa for acute bleeding episodes in this small series of children with inherited platelet function defects but larger studies are warranted, particularly as rVIIa is a relatively low-risk treatment approach for these disorders.

Recombinant factor VIIa enhances deposition of platelets with congenital or acquired alpha IIb beta 3 deficiency to endothelial cell matrix and collagen under conditions of flow via tissue factor-independent thrombin generation

A novel approach to treat bleeding episodes in patients with Glanzmann thrombasthenia (GT) and perhaps also in patients receiving alpha IIb beta 3 inhibitors is the administration of recombinant factor VIIa (rFVIIa). The mechanism of action of rFVIIa in these patients is, however, still unclear. We studied the effect of rFVIIa-mediated thrombin formation on adhesion of alpha IIb beta 3-deficient platelets under flow conditions. Adhesion of alpha IIb beta 3-deficient platelets to the extracellular matrix (ECM) of stimulated human umbilical vein endothelial cells or to collagen type III was studied using a model system with washed platelets and red cells. When alpha IIb beta 3-deficient platelets were perfused over the surface at arterial shear rate for 5 minutes, a low surface coverage was observed (GT platelets, mean +/- SEM, 37.5% +/- 5.0%; normal platelets preincubated with an RGD-containing peptide, 7.4% +/- 2.1%). When rFVIIa, together with factors X and II, was added to the perfusate, platelet deposition significantly increased (GT platelets, mean +/- SEM, 67.0% +/- 4.3%; normal platelets preincubated with an RGD-containing peptide, 48.2% +/- 2.9%). The same effect was observed when normal platelets were pretreated with the commercially available anti-alpha IIb beta 3 drugs abciximab, eptifibatide, or tirofiban. It was shown that tissue factor-independent thrombin generation (presumably induced by binding of rFVIIa to adhered platelets) was responsible for the increase in platelet deposition. In conclusion, defective adhesion of alpha IIb beta 3-deficient platelets to ECM can be restored by tissue factor-independent rFVIIa-mediated thrombin formation. The enhanced generation of platelet procoagulant surface facilitates fibrin formation, so that lack of platelet aggregate formation might be compensated for.

Molecular basis of Glanzmann's Thrombasthenia and current strategies in treatment

Glanzmann Thrombasthenia, an exceptional inherited platelet disorder is characterized by a complete lack of platelet aggregation due to a defect in the alpha(IIb)beta(3) complex or to a qualitative abnormality of this complex. Advances in molecular biology have permitted to precise the molecular abnormality on alpha(IIb) or beta(3) genes responsible for the disease and have also contributed to a better knowledge of normal platelet physiology. Hemorrhages are the main clinical problem. Current principles of therapeutic management are proposed, with special reference to the risk of platelet alloimmunisation.