Comparative thrombotic event incidence after infusion of recombinant factor VIIa vs. factor VIII inhibitor bypass activity-reply to a rebuttal

The use of FEIBA for refractory bleeding in cardiac surgery - a systematic review

INTRODUCTION

Significant blood loss during cardiac surgery is associated with a significant increase in morbidity and mortality. Factor Eight Inhibitor Bypassing Activity (FEIBA), a hemostatic bypassing agent mainly used in hemophiliac patients, has also been used for intractable surgical bleeding during cardiac surgical procedures in non-hemophiliac patients. However, concerns exist that its use may be linked to increased incidence of perioperative adverse effects including thrombotic complications.

AREAS COVERED

A systematic literature search was performed on MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases for all studies that reported the administration of FEIBA for treatment of bleeding during adult cardiac surgery in non-hemophiliac patients. After selecting of title and abstracts, two authors assessed the methodological quality of the full-text articles prior to final inclusion in the manuscript.

EXPERT OPINION

The safety profile of FEIBA was determined through an aggregate count of adverse events. Major complications included renal failure, re-operation for unresolved bleeding, postoperative mortality, and thromboembolic events. Overall, there is insufficient robust evidence to make a definitive conclusion about the safety or efficacy of using of FEIBA as a hemostatic agent in the setting of cardiac surgery.

Management of acquired haemophilia A

Acquired haemophilia A is an auto-immune disease caused by an inhibitory antibody to factor VIII. The pattern of bleeding varies but patients remain at risk of life threatening bleeding until the inhibitor has been eradicated. The cornerstones of management are; rapid and accurate diagnosis, control of bleeding, investigation for an underlying cause and eradication of the inhibitor by immunosuppression. Patients should always be managed jointly with a specialist centre even if they present without significant bleeding. Despite an extensive literature, few controlled data are available and treatment guidelines are based on expert opinion. To treat bleeds recombinant factor VIIa and activated prothrombin complex concentrate are equally efficacious but both are superior to factor VIII or desmopressin. Immunosuppression should be started as soon as the diagnosis is made. Commonly used regimens are steroids alone or combined with cytotoxic agents. Rituximab is being used more widely but current evidence does not suggest that it improves outcomes or reduces side effects.

Advances in the understanding of acquired haemophilia A: implications for clinical practice

Acquired haemophilia A is an auto-immune disease caused by an inhibitory antibody to factor VIII. Patients with an acquired factor VIII inhibitor are at risk of life- and limb-threatening bleeding until the inhibitor has been eradicated. Management relies on rapid and accurate diagnosis, control of bleeding episodes, investigation for a precipitating cause and eradication of the inhibitor by immunosuppression. Patients should always be managed jointly with a specialist centre even if they present without overt bleeding. Despite an extensive literature, few controlled data are available and management guidelines are predominantly based on case reports, retrospective cohorts and expert opinion. This paper reviews the current literature on incidence, pathogenesis, diagnosis, haemostatic therapy and inhibitor eradication strategies. Potential future developments are discussed.

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.

Factor VIII inhibitor bypassing activity (FEIBA) - addressing safety issues

Bypassing therapy is usually necessary to control or prevent bleeding episodes in patients with haemophilia A or B and high-titre inhibitors. Factor VIII inhibitor bypassing activity (FEIBA) has a long history of successful use in the acute, surgical and prophylactic treatment settings, but safety concerns have made some reluctant to administer this bypassing agent. A review of the literature and clinical trial data show that FEIBA has a low prevalence of thrombosis, a low prevalence of anamnesis that does not impact haemostatic efficacy and an excellent record of pathogen safety and clinical tolerability.

Treatment of acquired hemophilia A

Acquired hemophilia A (AH) is an autoimmune disease that leads to potentially severe bleeding. Management relies on rapid and accurate diagnosis, control of bleeding episodes and eradication of the inhibitor by immunosuppression. There is extensive literature about the disease but only few controlled data are available. This paper reviews the current literature on treatment strategies for hemostatic therapy and inhibitor eradication. Potential future developments are discussed.

The diagnosis and management of factor VIII and IX inhibitors: a guideline from the United Kingdom Haemophilia Centre Doctors Organisation

The revised UKHCDO factor (F) VIII/IX Inhibitor Guidelines (2000) are presented. A schema is proposed for inhibitor surveillance, which varies according to the severity of the haemophilia and the treatment type and regimen used. The methodological and pharmacokinetic approach to inhibitor surveillance in congenital haemophilia has been updated. Factor VIII/IX genotyping of patients is recommended to identify those at increased risk. All patients who develop an inhibitor should be considered for immune tolerance induction (ITI). The decision to attempt ITI for FIX inhibitors must be carefully weighed against the relatively high risk of reactions and the nephrotic syndrome and the relatively low response rate observed in this group. The start of ITI should be deferred until the inhibitor has declined below 10 Bethesda Units/ml, where possible. ITI should continue, even in resistant patients, where it is well tolerated and so long as there is a convincing downward trend in the inhibitor titre. The choice of treatment for bleeding in inhibitor patients is dictated by the severity of the bleed, the current inhibitor titre, the previous anamnestic response to FVIII/IX, the previous clinical response and the side-effect profile of the agents available. We have reviewed novel dose-regimens and modes of administration of FEIBA (factor VIII inhibitor bypassing activity) and recombinant activated FVII (rVIIa) and the extent to which these agents may be used for prophylaxis and surgery. Bleeding in acquired haemophilia is usually treated with FEIBA or rVIIa. Immunosuppressive therapy should be initiated at the time of diagnosis with Prednisolone 1 mg/kg/d +/- cyclophosphamide. In the absence of a response to these agents within 6 weeks, second-line therapy with Rituximab, Ciclosporin A, or other multiple-modality regimens may be considered.