Recombinant Factor VIIa (Eptacog Alfa)

What Can De Novo Protein Design Bring to the Treatment of Hematological Disorders?

Protein therapeutics have been widely used to treat hematological disorders. With the advent of de novo protein design, protein therapeutics are not limited to ameliorating natural proteins but also produce novel protein sequences, folds, and functions with shapes and functions customized to bind to the therapeutic targets. De novo protein techniques have been widely used biomedically to design novel diagnostic and therapeutic drugs, novel vaccines, and novel biological materials. In addition, de novo protein design has provided new options for treating hematological disorders. Scientists have designed protein switches called Colocalization-dependent Latching Orthogonal Cage-Key pRoteins (Co-LOCKR) that perform computations on the surface of cells. De novo designed molecules exhibit a better capacity than the currently available tyrosine kinase inhibitors in chronic myeloid leukemia therapy. De novo designed protein neoleukin-2/15 enhances chimeric antigen receptor T-cell activity. This new technique has great biomedical potential, especially in exploring new treatment methods for hematological disorders. This review discusses the development of de novo protein design and its biological applications, with emphasis on the treatment of hematological disorders.

Hemostatic Management of Trauma-Induced Coagulopathy

Trauma-induced coagulopathy is a primary factor in many trauma-related fatalities. Management hinges upon rapid diagnosis of coagulation abnormalities and immediate administration of appropriate hemostatic agents. Use of crystalloids and packed red blood cells has traditionally been the core of trauma resuscitation, but current massive transfusion protocols include combination therapy with fresh frozen plasma and predefined ratios of platelets to packed red blood cells, limiting crystalloid administration. Hemostatic agents such as tranexamic acid, prothrombin complex concentrate, fibrinogen concentrate, and, in cases of refractory bleeding, recombinant activated factor VIIa may also be warranted. Goal-directed resuscitation using viscoelastic tools allows specific component-centered therapy based on individual clotting abnormalities that may limit blood product use and thromboembolic risks and may lead to reduced mortality. Because of the complex management of patients with trauma-induced coagulopathy, critical care nurses must be familiar with the pathophysiology, acute diagnostics, and pharmacotherapeutic options used to treat these patients.

Factor VIIa analog has marked effects on platelet function and clot kinetics in blood from patients with hemophilia A

To evaluate the hemostatic effects of NN1731 and rFVIIa, an ex-vivo study in hemophilia patients used the Hemodyne Hemostasis Analysis System (HAS) to measure platelet contractile force (PCF), clot elastic modulus (CEM), and force onset time (FOT), and the Haemoscope Thrombelastograph (TEG) to measure reaction time (R), kinetics time (K), and maximum amplitude (MA). Blood samples from 10 healthy volunteers and 10 Factor VIII-deficient patients of varying severity (mild, moderate, severe), were spiked with rFVIIa and NN1731 (both 0.64 and 1.28 microg/ml, respectively) and analyzed to characterize platelet function and clot kinetics. There was wide variability in the rFVIIa response. NN1731 had greater and more consistent effects on PCF, CEM, FOT, R, and K relative to rFVIIa, in all hemophilia groups. The lowest NN1731 concentration (0.64 microg/ml) shortened R and FOT, and increased CEM and PCF more than rFVIIa 1.28 microg/ml. NN1731 normalized clotting parameters equivalent to values obtained in healthy volunteers. FOT and R were highly correlated (r = 0.96). No correlation was observed between CEM and MA. NN1731 produced less variable, more pronounced and predictable ex-vivo hemostatic effects on PCF, CEM, FOT, R and K than rFVIIa in all hemophilia groups. HAS and TEG assays provided similar estimates of FOT and R, however CEM appeared to be more sensitive than MA to changes in clot firmness.

Recombinant factor VIIa (eptacog alfa): a review of its use in congenital hemophilia with inhibitors, acquired hemophilia, and other congenital bleeding disorders

Recombinant factor VIIa (NovoSeven; also known as recombinant activated factor VII or eptacog alfa) is structurally similar to human plasma-derived coagulation factor VIIa, but is manufactured using DNA biotechnology. Recombinant factor VIIa interacts with thrombin-activated platelets to produce a thrombin burst leading to accelerated fibrin clot formation localized to the site of vascular injury. It is approved in many countries for use as an intravenous hemostatic agent in patients with congenital hemophilia with inhibitors, and also for acquired hemophilia, factor VII deficiency, and Glanzmann thrombasthenia in some countries. Studies have shown it to be effective and generally well tolerated when used intravenously to treat bleeding episodes or provide hemostatic cover during surgery in patients with congenital hemophilia with inhibitors, acquired hemophilia, factor VII deficiency or Glanzmann thrombasthenia. Based on available data, its efficacy in terms of patient-assessed response may be similar to that of activated prothrombin complex concentrate (aPCC), but treatment with a single 270 microg/kg dose of recombinant factor VIIa might reduce the need for rescue therapy compared with aPCC. Recombinant factor VIIa is not immunogenic in patients with hemophilia, does not produce an anamnestic response in hemophilia patients with inhibitors, and has very low thrombogenicity. It is recommended in guidelines as the treatment of choice for bleeds in patients with hemophilia B with high-responding inhibitors and for patients with factor VII deficiency, and is also a first-line therapeutic option for high-responder hemophilia A patients with inhibitors and those with acquired hemophilia. Cost data from pharmacoeconomic analyses support its use in hemophilia patients with inhibitors. Thus, recombinant factor VIIa is a valuable treatment option for patients with these rare, but potentially serious, bleeding disorders.

A benefit-risk review of systemic haemostatic agents: part 1: in major surgery

Systemic haemostatic agents play an important role in the management of blood loss during major surgery where significant blood loss is likely and their use has increased in recent times as a consequence of demand for blood products outstripping supply and the risks associated with transfusions. Their main application is as prophylaxis to reduce bleeding in major surgery, including cardiac and orthopaedic surgery and orthotopic liver transplantation. Aprotinin has been the predominant agent used in this setting; of the other antifibrinolytic agents that have been studied, tranexamic acid is the most effective and epsilon-aminocaproic acid may also have a role. Eptacog alfa (recombinant factor VIIa) has also shown promise. Tranexamic acid, epsilon-aminocaproic acid and eptacog alfa are generally well tolerated; however, when considering the methods to reduce or prevent blood loss intra- and postoperatively, the benefits of these agents need to be weighed against the risk of adverse events. Recently, concerns have been raised about the safety of aprotinin after an association between increased renal dysfunction and mortality was shown in retrospective observational studies and an increase in all-cause mortality with aprotinin relative to tranexamic acid or epsilon-aminocaproic acid was seen after a pre-planned periodic analysis of the large BART (Blood conservation using Antifibrinolytics in a Randomized Trial) study. The latter finding resulted in the trial being halted, and aprotinin has subsequently been withdrawn from the market pending detailed analysis of efficacy and safety results from the study. Part 1 of this benefit-risk review examines the efficacy and adverse effect profiles of systemic haemostatic agents commonly used in surgery, and provides individual benefit-risk profiles that may assist clinicians in selecting appropriate pharmacological therapy in this setting.

Effect of recombinant factor VIIa variant (NN1731) on platelet function, clot structure and force onset time in whole blood from healthy volunteers and haemophilia patients

NN1731 is a novel variant of recombinant factor VIIa (rFVIIa) that binds to activated platelets, but has greater enzymatic activity than rFVIIa in generating FXa and thrombin. The effect of NN1731 on clot structure and platelet function was characterized ex vivo in whole blood from healthy volunteers and haemophilic patients. Blood samples from six healthy volunteers, nine haemophilia A patients with and without inhibitors and one acquired haemophilia A patient, were spiked with increasing concentrations (0.32, 0.64 and 1.28 microg mL(-1)) of rFVIIa and NN1731. Platelet contractile force (PCF) or platelet function, clot elastic modulus (CEM) or clot structure, and force onset time (FOT) or the thrombin generation time (TGT) were determined using the Hemodyne Hemostasis Analysis System (HAS). Baseline PCF, CEM and FOT values in patients were abnormal compared to healthy volunteers' baseline values. Overall, haemophilia blood samples with or without inhibitors spiked with NN1731 had significantly greater PCF, CEM and shorter FOT values relative to samples spiked with corresponding doses of rFVIIa. The variability in response to treatment between patients was greater with rFVIIa compared to NN1731. At 1.28 microg mL(-1) (90 microg kg(-1)), NN1731 normalized PCF, CEM and FOT in nine of 10 patients, while rFVIIa normalized these parameters in four of 10 patients. Increasing in vitro concentrations of NN1731 normalized platelet function, clot structure and thrombin generation consistently in haemophilia blood with or without inhibitors. NN1731 may be a promising haemostatic agent for patients with bleeding disorders. These results should be confirmed in an in vivo study.

Coagulation factor concentrates: past, present, and future

Clotting factor transfusions are vital for people with diseases such as haemophilia. In the 1970s and 1980s, transfusions with pooled plasma led to a devastatingly high number of recipients becoming infected with blood-borne pathogens such as HIV and hepatitis C. This epidemic triggered the development of virus-free factor concentrates through a combination of improved donor selection and screening, effective virucidal technologies, and recombinant protein expression biotechnology. There is now a wide range of recombinant factor concentrates, and an impressive safety record with respect to pathogen transmission. However, remaining therapeutic challenges include the potential threat of transmission of prions and other pathogens, the formation of inhibitory alloantibodies, and the international disparity that exists in product availability due to differences in licensure status as well as prohibitively high costs. In the future, it is likely that bioengineered recombinant proteins that have been modified to enhance pharmacokinetic properties or reduce immunogenicity, or both, will be used increasingly in clinical practice.

Haemophilia therapies

In the last few decades dramatic improvements in the management of haemophilia patients have occurred. Haemophilia has moved from a fatal or disabling disease to a hereditary disorder with available treatment and much better clinical outcomes. The safety of antihaemophilic factor concentrates has been dramatically improved and, in a multidisciplinary environment including haematologists, orthopaedic surgeons, paediatrics, infectiologists, specialised nurses and physiotherapists, complications related to haemophilia are now limited, markedly improving the quality of life of haemophiliacs. One can even think that the cure of haemophilia through gene therapy might occur in the next decades. Keeping this ultimate aim in mind, efforts at present are mainly focused on bioengineered Factor VIII/Factor IX concentrates with increased efficacy or longer half-life or decreased immunogenicity. In addition, several preclinical and clinical studies are being carried out for optimising and individually tailoring the therapeutic regimens of antihaemophilic therapies using global haemostasis tests in combination with the routine coagulation assays.

Recombinant factor VIIa (eptacog alfa): a pharmacoeconomic review of its use in haemophilia in patients with inhibitors to clotting factors VIII or IX

Recombinant factor VIIa (NovoSeven; also known as recombinant activated factor VII or eptacog alfa) is indicated as an intravenous haemostatic agent in haemophilia patients with inhibitors to clotting factors VIII or IX. In noncomparative trials in haemophilia patients with inhibitors, on-demand home treatment with recombinant factor VIIa was effective in controlling episodes of mild to moderate bleeding and well tolerated, with early treatment being associated with a greater rate of success and the need for fewer doses than delayed treatment. Prophylactic treatment with recombinant factor VIIa was also effective in maintaining haemostasis in patients with this indication undergoing surgery. Relative to prior treatment with plasma-derived agents, treatment with recombinant factor VIIa was associated with improvements in health-related quality of life in a cost-utility study in haemophilia patients with inhibitors in Australia. In well designed decision-model cost analyses conducted from a healthcare payer perspective in several countries, on-demand treatment with recombinant factor VIIa to control mild to moderate bleeding episodes in this patient population was predicted to be cost saving or cost neutral relative to on-demand treatment with intravenous activated prothrombin complex concentrate (aPCC). Although the acquisition cost of recombinant factor VIIa was greater than that of aPCC in some studies, the greater initial efficacy of recombinant factor VIIa than aPCC resulted in lower predicted total medical costs. Results were generally robust to plausible changes in key parameters. Orthopaedic surgery with recombinant factor VIIa to maintain haemostasis in haemophilia patients with inhibitors was generally predicted to be cost saving, relative to not having surgery, over the medium to long term in modelled cost analyses from a healthcare payer perspective in the UK and US. The initial cost of surgery was high, but the difference in costs between patients undergoing or not undergoing surgery was predicted to decline over time, as savings were realised from the decrease in the number of bleeding episodes requiring treatment in patients who underwent surgery. In haemophilia patients with inhibitors, recombinant factor VIIa is clinically effective in controlling mild to moderate bleeds, and in maintaining haemostasis in patients undergoing orthopaedic surgery. Available pharmacoeconomic data from several countries, despite inherent limitations, support the use of recombinant factor VIIa as a treatment option that is at least cost neutral relative to aPCC in treating mild to moderate bleeds in this patient population. In addition, orthopaedic surgery with recombinant factor VIIa to maintain haemostasis in haemophilia patients with inhibitors is generally cost saving relative to not having surgery over the medium to long term, as the acquisition costs of recombinant factor VIIa are offset by cost savings resulting from the decrease in the number of joint-related bleeds.

Recombinant factor VIIa reverses the inhibitory effect of aspirin or aspirin plus clopidogrel on in vitro thrombin generation

BACKGROUND

Antiplatelet drugs constitute the therapy of choice for acute coronary syndromes, but bleeding can be a side-effect requiring treatment. Restoration of normal platelet activity is also mandatory before urgent surgery. This study investigated: (a) whether a regimen of aspirin or clopidogrel plus aspirin significantly inhibited platelet thrombin generation (TG); and (b) the reversal of this inhibition by recombinant activated factor VII (rFVIIa).

METHODS AND RESULTS

TG was evaluated by the lag time, time to peak, peak of TG, and area under the curve after 35 min of assay (AUC(0 --> 35 min)). These measures were examined by the calibrated automated thrombography method in 22 healthy volunteers, 22 volunteers after a 100 mg day(-1) aspirin intake (200 mg first day) for 5-7 days, and 22 healthy volunteers after aspirin 100 mg day(-1) (200 mg first day) plus clopidogrel 75 mg day(-1) (300 mg first day) for 4-7 days. The TG parameters were measured under basal conditions and after platelet stimulation by sodium arachidonate (AA), adenosine 5'-diphosphate (ADP), collagen and rFVIIa in normal non-aspirinated as well as in vivo aspirinated platelet-rich plasma (PRP) or aspirin plus clopidogrel PRP. Lag time was shorter (P < 0.05), and peak of TG and AUC(0 --> 35 min) were significantly greater (P < 0.01 for both), in PRP activated with ADP, collagen, AA or FVIIa than in non-activated PRP from normal subjects. Both non-activated PRP and activated PRP prepared from platelets obtained from volunteers after aspirin intake showed significant prolongation of the time parameters but there was less effect on peak of TG and AUC(0 --> 35 min). For most parameters, aspirin plus clopidogrel administration showed to be more effective compared with the effect obtained by aspirin alone. When rFVIIa was added to ASA-PRP or ASA + Clop PRP, lag time (P < 0.001 for all) and time to peak (P < 0.001-0.017) were significantly shortened, indicating that rFVIIa reverses the inhibitory effect of these anti-aggregating agents.

CONCLUSION

Platelets activated by AA, ADP, collagen or FVIIa triggered TG. This effect was inhibited by aspirin plus clopidogrel, suggesting an additional benefit of this drug combination for preventing thrombosis. rFVIIa reverses the inhibitory effect of aspirin or aspirin plus clopidogrel, and could be useful for bleeding complications or when acute surgery is needed during treatment with these antiplatelet drugs.

Acquired hemophilia A

Acquired hemophilia A is a rare but severe autoimmune bleeding disorder, resulting from the presence of autoantibodies directed against clotting factor VIII. The etiology of the disorder remains obscure, although approximately half of all cases are associated with other underlying conditions. A prompt diagnosis and appropriate management enable effective control of this acquired hemorrhagic disorder: the aims of therapy are to terminate the acute bleeding episode and eliminate or reduce the inhibitor. The recent availability of bypassing agents, first activated prothrombin complex concentrates and then recombinant activated factor VII, has significantly reduced mortality during the acute phase of the disease in patients with high titer inhibitors. On another front, immunosuppressive therapy (corticosteroids and cytotoxic agents, alone or in various combinations) has resulted in long-term inhibitor suppression in up to 70% of the cases. Moreover, new therapeutic strategies (anti-CD20 monoclonal antibody and immune tolerance protocols) are very promising and may further improve the prognosis of acquired hemophilia A.

Critical bleeding in vascular surgery: expanding the indication of recombinant activated factor VII

Recombinant activated factor VII (rFVIIa) is considered a universal hemostatic agent. We present our experience with rFVIIa in vascular surgery patients who developed major hemorrhagic complications with no obvious major vessel bleeding as an expansion of the indications of rFVIIa. Of 973 major complex vascular procedures, 18 patients with intractable bleeding were administered 40 to 80 mug/kg rFVIIa. Blood and by-products transfused, pH, coagulation profile, platelet count, and preoperative antiplatelets and anticoagulants were recorded.Twelve patients (67%) showed clinical improvement. Six remained unstable despite further hemostatic measures and died perioperatively. Thirty-three percent (n = 6) received over 20 U of blood before rFVIIa administration. All but one died within the first 24 hours (p = .0175). Seven patients had acidosis with a pH of 7.3 or less. Five of them died within 24 hours (p = .05). Six patients had a platelet count below 100,000/cm3, five of whom died perioperatively (p = .0175). Patients with an international normalized ratio above 1.2 had a better survival rate because rFVIIa was used early. There were no signs of systemic or local thrombotic events. The amount of blood and plasma transfused was significantly reduced after rFVIIa administration.rFVIIa is a safe adjunct for patients with significant hemorrhagic complications, with a low risk of thrombotic complications. We found it effective if administered early with measures to achieve hemodynamic stability and correction of acidosis.

Ineffective off-label use of recombinant activated factor VII in a case of bone-marrow transplantation-related gastrointestinal bleeding

BACKGROUND

For patients with a normal coagulation system, who experience serious bleeding, sound evidence for recombinant activated factor VII (rFVIIa) as an effective haemostatic agent is only scarcely available so far from controlled clinical trials. In systematic reviews on the clinical use of rFVIIa, treatment failures were only rarely reported.

CASE PRESENTATION

We present a 45-year old, Caucasian male with persistent intestinal bleeding due to enterocolitis associated with cytomegalovirus infection and acute graft-versus-host-disease. He had received allogeneic peripheral blood stem cell transplantation from an unrelated HLA-identical donor because of chronic myelogenous leukaemia diagnosed two years earlier. Bleeding started at day 18 after transplantation with bloody diarrhea, which was treated with multiple transfusions of fresh frozen plasma, platelet, and red blood cell concentrates, and continued relentlessly, despite all efforts, including continued transfusions, high-dose prednisolone, broad antibiotic and antiviral coverage, and tranexamic acid. Recombinant FVIIa was started at boluses of 90-120 mug/kg every 4-8 hours. Despite more than 10 doses, recurrent severe bleeding progressed to refractory shock, multiorgan failure and death.

CONCLUSIONS

Little can be concluded from single case reports of clinical improvement, because publication bias in favour of positive effects is likely. Our case suggests that rFVIIa is not a panacea, in particular for severe bleeding after bone-marrow transplantation. As long as rigorous, controlled studies or comprehensive registries are lacking, conventional interventions remain the standard of care in non-haemophilic patients with severe bleeding.

Inherited Platelet Disorders

The inherited platelet disorders are a heterogeneous collection of rare diseases that are infrequently encountered in clinical practice. They are, however, fascinating abnormalities, which have taught us a great deal about normal platelet biochemistry and physiology. In this section of the presentation we will review disorders of the platelet membrane, platelet granule packaging disorders, the hereditary macrothrombocytopenias, platelet signaling disorders and disorders of platelet coagulant function. The molecular basis of the disorders, the cardinal features of their clinical presentation and best methods to make their diagnosis and the latest information regarding therapy will be presented.