Recombinant factor VIIa: review of efficacy, dosing regimens and safety in patients with congenital and acquired factor VIII or IX inhibitors

Emory University, Atlanta, Georgia, United States
Journal of Thrombosis and Haemostasis (Impact Factor: 5.55). 07/2004; 2(6):899-909. DOI: 10.1111/j.1538-7836.2004.00759.x
Source: PubMed

ABSTRACT Recombinant factor (rF)VIIa has been available to clinicians since 1996 and has an excellent safety record after almost three-quarters of a million doses have been administered. This paper will review the current clinical experience with rFVIIa dosing in acquired and congenital hemophilia with inhibitors and chronicle all spontaneous and clinical trial reports of thrombotic adverse events as of April 2003. Standard dosing of rFVIIa (90 micro g kg(-1)) allows binding of FVIIa to the surface of an activated platelet and can directly activate factor X in the absence of tissue factor. Experience with bolus dosing suggests that higher dosing (>200 micro g kg(-1)) may be more efficacious in treating hemophilia patients. Clinical trials are ongoing to validate this observation. Continuous infusion dosing may be efficacious for major surgery but high infusion rates (50 micro g kg(-1) h(-1)) might be needed. The relationship between dose of rFVIIa, amount of thrombin generated and measurable FVIIa level is still not known and perhaps newer testing which measures thrombin generation might be more advantageous. Relatively few thrombotic events have been associated with rFVIIa. Known factors predisposing to thrombosis were present in 20 of the 25 (80%) hemophilia patients who were reported spontaneously or who developed a thrombosis during a clinical trial. Additionally, thrombotic events have not increased despite a growing experience with higher dosing of rFVIIa.

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    ABSTRACT: Background Serious thromboembolic events connected with rFVIIa therapy in hemophilia patients are rare. Only three cases are reported in children, all of them with hemophilia A.Case presentationWe present unique case of patient with hemophilia B and high titer inhibitors to coagulation FIX, who developed severe renal damage due to thromboembolic event during rFVIIa therapy, associated with unsuspected renovascular anomalies.Conclusion Caution is necessary if hematuria B requires administration of rFVIIa. US color doppler renal imaging before and after drug administration should be sufficient as an early warning.
    BMC Pediatrics 12/2014; 14(1):315. DOI:10.1186/s12887-014-0315-2 · 1.92 Impact Factor
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    ABSTRACT: Treatment of patients with hemophilia A and B has undergone significant advances during the past 2 decades. However, despite these advances, the development of antibodies that inhibit the function of infused clotting factor remains a major challenge and is considered the most significant complication of hemophilia treatment. This chapter reviews current tools available for the care of patients with inhibitors and highlights areas where progress is imminent or strongly needed. For management of bleeding, bypassing agents remain the mainstay of therapy. Recombinant factor VIIa and activated prothrombin complex concentrates are similarly effective in populations of patients with hemophilia and inhibitors; however, individuals may show a better response to one agent over another. Recent studies have shown that prophylaxis with bypassing agents can reduce bleeding episodes by ∼50%-80%. The prophylactic use of bypassing agents is an important tool to reduce morbidity in patients before they undergo immune tolerance induction (ITI) and in those with persistent high titer inhibitors, but cost and lack of convenience remain barriers. Because of the significant burden that inhibitors add to the individual patient and the health care system, inhibitor eradication should be pursued in as many patients as possible. ITI is an effective tool, particularly in patients with severe hemophilia A and good risk profiles, and leads to a return to a normal factor VIII response in ∼60% of patients. However, for the group of patients who fail to respond to ITI or have hemophilia B, new and improved tools are needed. © 2014 by The American Society of Hematology. All rights reserved.
    Blood 11/2014; 124(23):3365-3372. DOI:10.1182/blood-2014-05-577643 · 9.78 Impact Factor
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    ABSTRACT: Background: Vatreptacog alfa, a recombinant factor VIIa (rFVIIa) analog with three amino acid substitutions and 99% identity to native FVIIa, was developed to improve the treatment of hemophilic patients with inhibitors. Objectives: To confirm the safety and assess the efficacy of vatreptacog alfa in treating bleeding episodes in hemophilic patients with inhibitors. Patients and methods: In this international, multicenter, randomized, double-blind, active-controlled, crossover, confirmatory phase III trial (adept (TM) 2) in patients with hemophilia A or B and inhibitors, bleeds were randomized 3 : 2 to treatment with vatreptacog alfa (one to three doses at 80 mu g kg(-1)) or rFVIIa (one to three doses at 90 mu g kg(-1)). Treatment failures after three doses of trial product (TP) were managed according to the local standard of care. Results: In the 72 patients enrolled, 567 bleeds were treated with TP. Both vatreptacog alfa and rFVIIa gave 93% effective bleeding control at 12 h. Vatreptacog alfa was superior to rFVIIa in secondary efficacy outcomes, including the number of doses used to treat a bleed and sustained bleeding control 24-48 h after the first dose. Eight patients (11%) developed antibodies against vatreptacog alfa, including four with cross-reactivity against rFVIIa and one with an in vitro neutralizing effect to vatreptacog alfa. Conclusions: This large randomized controlled trial confirmed the well-established efficacy and safety profile of rFVIIa, and showed that vatreptacog alfa had similar or better efficacy than rFVIIa. However, because of the development of anti-drug antibodies, a positive benefit-risk profile is unlikely to be achieved with vatreptacog alfa.
    Journal of Thrombosis and Haemostasis 06/2014; 12(8). DOI:10.1111/jth.12634 · 5.55 Impact Factor

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