Treatment of factor XI inhibitor using recombinant activated factor VIIa

Factor XI deficiency: phenotypic age-related considerations and clinical approach towards bleeding risk assessment

ABSTRACT

Factor XI (FXI) deficiency is a rare bleeding disorder that presents complex challenges in patient assessment and bleeding risk management. Despite generally causing mild to moderate bleeding symptoms, clinical manifestations can vary, and bleeding tendency does not always correlate with FXI plasma levels or genotype. Our manuscript delves into the age-related nuances of FXI deficiency across an individual's lifespan. We emphasize issues faced by specific groups, including neonates and females of reproductive age experiencing abnormal uterine bleeding and postpartum hemorrhage. Older patients present unique challenges and concerns related to the management of bleeding as well as thrombotic complications. The current assortment of diagnostic laboratory assays shows limited success in predicting bleeding risk in the perisurgical setting of patients with FXI deficiency. This review explores the intricate interplay between individual bleeding profiles, surgical sites, and FXI activity levels. We also evaluate the accuracy of existing laboratory assays in predicting bleeding and discuss the potential role of investigational global assays in perioperative assessment. Furthermore, we outline our suggested diagnostic approach to refine treatment strategies and decision making. Available treatment options are presented, including antifibrinolytics, replacement products, and recombinant activated FVII. Finally, we discuss promising nonreplacement therapies for the treatment of rare bleeding disorders that can potentially address the challenges faced when managing FXI deficiency-related bleeding complications.

Factor XIa-specific IgG and a reversal agent to probe factor XI function in thrombosis and hemostasis

Thrombosis is a major cause of morbidity and mortality. Current antithrombotic drugs are not ideal in that they must balance prevention of thrombosis against bleeding risk. Inhibition of coagulation factor XI (FXI) may offer an improvement over existing antithrombotic strategies by preventing some forms of thrombosis with lower bleeding risk. To permit exploration of this hypothesis in humans, we generated and characterized a series of human immunoglobulin Gs (IgGs) that blocked FXIa active-site function but did not bind FXI zymogen or other coagulation proteases. The most potent of these IgGs, C24 and DEF, inhibited clotting in whole human blood and prevented FeCl3-induced carotid artery occlusion in FXI-deficient mice reconstituted with human FXI and in thread-induced venous thrombosis in rabbits at clinically relevant doses. At doses substantially higher than those required for inhibition of intravascular thrombus formation in these models, DEF did not increase cuticle bleeding in rabbits or cause spontaneous bleeding in macaques over a 2-week study. Anticipating the desirability of a reversal agent, we also generated a human IgG that rapidly reversed DEF activity ex vivo in human plasma and in vivo in rabbits. Thus, an active site-directed FXIa-specific antibody can block thrombosis in animal models and, together with the reversal agent, may facilitate exploration of the roles of FXIa in human disease.

Factor XI deficiency and orthognathic surgery: a case report on anesthesia management

Factor XI deficiency (Hemophilia C) is a very rare autosomal recessive bleeding disorder. Patients with factor XI deficiency do not typically show any spontaneous bleeding or specific symptoms. Sometimes those who have this disorder are identified during special situations such as trauma or surgery. Orthognathic surgery is particularly associated with a high bleeding risk. Therefore, great care must be taken when treating patients with bleeding disorders such as factor XI deficiency. There are a few reports that address the management of patients with bleeding disorders during orthognathic surgery. The current report describes a patient with factor XI deficiency who underwent Le Fort I osteotomy together with bilateral sagittal split osteotomy. The patient's condition was assessed using both rotation thromboelastometry (ROTEM™) and noninvasive measurements of total hemoglobin (SpHb) using Masimo Radical 7 (Masimo Co. CA, USA).

Acquired Factor XI Inhibitor Presenting as Spontaneous Bilateral Subdural Hematoma in an Elderly Patient

Development of autoantibodies against coagulation factors is an uncommon bleeding disorder associated with cancer, autoimmune conditions, pregnancy, or no apparent disease. Spontaneous FVIII inhibitors are the most frequently encountered; those against FXI have been only anecdotally reported. We report a case of acquired FXI inhibitor presenting as fatal intracranial spontaneous bleeding in an elderly patient with history of cancer and previous transfusions. Few cases of acquired FXI inhibitor have been reported in association with connective tissue disease, cancer, or surgery. Bleeding includes mucocutaneous bleeding, postsurgical hemorrhage, or life-threatening events. Treatment consists of arresting the bleeding and inhibitor eradication. High degree of suspicion is essential to promptly diagnose and treat this uncommon condition.

Factor deficiencies in pregnancy

Pregnancy, childbirth, and the puerperium are hemostatically challenging to women with bleeding disorders. This article provides general recommendations for the management of pregnant women with inherited coagulation disorders. Each factor deficiency is discussed, providing an up-to-date review of the literature and, where possible, guidance about how to manage patients throughout pregnancy, delivery, and the puerperium. The factor deficiencies covered are inherited abnormalities of fibrinogen; deficiencies of prothrombin, factor (F)V, FVII, FX, FXI, FXIII; combined deficiencies of FV and FVIII; and the inherited deficiency of vitamin K-dependent clotting factors. The management of carriers of hemophilia A and B is also discussed.

Elective orthopaedic surgery for haemophilia patients with inhibitors: single centre experience of 40 procedures and review of the literature

With the introduction of safe and effective factor VIII/IX-bypassing agents--recombinant activated factor VII (rFVIIa) and plasma-derived activated prothrombin complex concentrates (pd-APCC)--elective orthopaedic surgery (EOS) is a viable option for haemophilia patients with inhibitors. We report a series of patients with haemophilia and inhibitors undergoing EOS between 1997 and 2008 using bypassing agents to provide haemostatic cover. All inhibitor patients undergoing EOS and receiving rFVIIa, plasma-derived prothrombin complex concentrates (pd-PCC) or pd-APCC as haemostatic cover were included. Patients were operated on by the same surgeon and were managed by the same haemophilia treatment centre. Forty procedures (25 minor and 15 major) were conducted in 18 patients. Twenty-one minor cases were covered using rFVIIa, three with pd-PCC, and one with pd-APCC; all major cases were covered using rFVIIa. Bleeding was no greater than expected compared with a non-haemophilic population in all 25 minor procedures. In the major procedure group, there was no excessive bleeding in 40% of cases (6/15) and bleeding completely stopped in response to rFVIIa. For the remaining nine cases, bleeding response to rFVIIa was described as 'markedly decreased' or 'decreased' in 4/15 cases and 'unchanged' in 5/15 cases. Overall, efficacy of rFVIIa, based on final patient outcome, was 85%. One death occurred as a result of sepsis secondary to necrotizing fasciitis. Good control of haemostasis can be achieved with bypassing agents in haemophilia patients with inhibitors undergoing minor EOS; rFVIIa was used as an effective bypassing agent, enabling EOS in patients undergoing minor and major procedures.

Acquired hemophilia as the cause of life-threatening hemorrhage in a 94-year-old man: a case report

Introduction

Acquired factor VIII deficiency is a rare entity that can lead to severe and life-threatening bleeding. We describe a case of severe bleeding from the tongue secondary to acquired hemophilia and discuss treatment options, including aminocaproic acid and recombinant factor VIII, which have not been widely reported in the literature for the management of such patients.

Case presentation

A 94-year-old Caucasian man presented to our institution with diffuse bruising and extensive bleeding from the tongue secondary to mechanical trauma. He had no prior history of bleeding and his medical history was unremarkable except for dementia and hypertension. Coagulation studies revealed a prolonged activated partial thromboplastin time and a mixing study was consistent with the presence of an inhibitor. Quantitative assays revealed a reduced level of factor VIII activity (1%) and the presence of a factor VIII inhibitor, measured at seven Bethesda units, in the serum. Oral prednisone therapy (60mg/day) was given. He also received intravenous aminocaproic acid and human concentrate of factor VIII (Humate-P) and topical anti-thrombolytic agents (100 units of topical thrombin cream). His hospital course was prolonged because of persistent bleeding and the development of profuse melena. He required eight units of packed red blood cells for transfusion. Hospitalization was also complicated by bradycardia of unclear etiology, which started after infusion of aminocaproic acid. His activated partial thromboplastin time gradually normalized. He was discharged to a rehabilitation facility three weeks later with improving symptoms, stable hematocrit and resolving bruises.

Conclusions

Clinicians should suspect a diagnosis of acquired hemophilia in older patients with unexplained persistent and profound bleeding from uncommon soft tissues, including the tongue. Use of factor VIII (Humate-P) and aminocaproic acid can be useful in this coagulopathy but clinicians should be aware of possible life-threatening side effects in older patients, including bradycardia.

Factor XI deficiency—resolving the enigma?

The management of factor XI deficiency is not straightforward for three reasons: firstly, the role of this factor in the coagulation pathway is not clearly understood; secondly, the bleeding tendency, although mild, is unpredictable and does not clearly relate to the factor XI level; and thirdly, all treatment products, although available, have some potentially serious side effects. These factors (or enigmas) contribute to the variable management of patients with this coagulation factor deficiency, but recent research is helping to clarify some of these areas.

Update on the physiology and pathology of factor IX activation by factor XIa

Factor IX is a key component of the plasma system that forms a fibrin clot at a site of vascular injury. Activation of factor IX by factor XIa is required in certain situations to prevent bleeding from premature clot degradation. Factor XIa is a coagulation protease comprised of two identical subunits. The biochemical and physiologic implications of this unusual structural feature are being actively investigated. Congenital factor XI deficiency causes a mild-to-moderate bleeding disorder, with hemorrhage typically involving the oral/nasal cavities and the urinary tract. Current treatment recommendations take this tissue-specific bleeding pattern into account and target factor replacement to certain types of procedures and clinical situations. Results from animal models and human population studies indicate that factor XI contributes to thromboembolic disease. This protease may therefore be a legitimate therapeutic target.

Successful use of recombinant factor VIIa (NovoSeven) during cardiac surgery in a pediatric patient with congenital factor XI deficiency

We report our experience with the use of recombinant activated factor VII (rFVIIa) during cardiac surgery in a 4.5-year-old boy with severe congenital FXI deficiency and a congenital heart disease. After weaning the patient from cardiopulmonary bypass, the first intravenous dose of rFVIIa (90 microg/kg) was administered. This same dosage was repeated eight more times, at 2- to 4-hour intervals postoperatively. There was no bleeding during and after surgery. rFVIIa treatment may be used successfully in children with severe FXI deficiency in major operations such as open heart surgery.

Recombinant Factor VIIa for the Prophylaxis of Perioperative Hemorrhage in a Patient With Congenital Factor XI Deficiency Undergoing Brain Tumor Neurosurgery

The authors report on the first successful use of recombinant activated factor VII for the prophylaxis of bleeding during brain tumor neurosurgery in a patient suffering from inherited factor XI deficiency. Using the agent, surgery was performed without any bleeding complications. In this setting, off-label use of recombinant activated factor VII appears to be a promising alternative for patients suffering from this rare hemostatic defect with hitherto limited therapeutic options.

Uneventful cesarean delivery with administration of factor XI concentrate in a patient with severe factor XI deficiency

Factor XI (FXI) is a procoagulant factor and antifibrinolytic agent, and its absence causes a bleeding tendency. FXI deficiency is autosomal in inheritance, with severe FXI deficiency in homozygotes and partial deficiency in heterozygotes. A 24-year-old primigravida with an uneventful pregnancy and no history of bleeding manifestations was admitted to our department at 38 weeks of gestation. Her blood count and serum biochemistry findings were normal except for a coagulation screen, which revealed a prolonged activated partial thromboplastin time (APTT) of 63 seconds (normal range, 24-35 seconds). The measured FXI coagulant activity of 8 IU/dL (reference range, 70-150 IU/dL) established a diagnosis of severe FXI deficiency. The breech presentation of the fetus prompted the decision for cesarean delivery under general anesthesia. We administered a single dose of FXI concentrate (15 IU/kg), which corrected the APTT to 34 seconds. The cesarean delivery was uncomplicated, and postpartum recovery of the mother and her baby was uneventful with no bleeding complications. The finding of an isolated prolonged APTT should prompt obstetricians to consider FXI deficiency. The appropriate use of factor FXI concentrate in managing obstetric patients with FXI deficiency can minimize potential bleeding complications and ensure an optimal outcome for both mother and neonate.

Perioperative use of modified thrombelastography in factor XI deficiency: a helpful method to assess drug effects

Factor XI deficiency is a rare, hereditary bleeding disorder associated with a trauma-related bleeding tendency, caused by insufficient generation of the thrombin activatable fibrinolysis inhibitor (TAFI) evoking increased fibrinolysis. We present the case of a five year old girl with homozygote, severe factor XI deficiency presenting for surgery on two occasions. Modified thrombelastography (ROTEM) was used to assess effects of factor XI deficiency on coagulation, endogenous fibrinolysis, and potential effects of tranexamic acid, aprotinin and recombinant, activated Factor VII in an in vitro model of hyperfibrinolysis. According to our data and in consideration of the mechanisms of factor XI deficiency we decided on prophylactic use of tranexamic acid.

The obstetric and gynaecological management of women with inherited bleeding disorders - review with guidelines produced by a taskforce of UK Haemophilia Centre Doctors' Organization

The gynaecological and obstetric management of women with inherited coagulation disorders requires close collaboration between obstetrician/gynaecologists and haematologists. Ideally these women should be managed in a joint disciplinary clinic where expertise and facilities are available to provide comprehensive assessment of the bleeding disorder and a combined plan of management. The haematologist should arrange and interpret laboratory tests and make provision for appropriate replacement therapy. These guidelines have been provided for healthcare professionals for information and guidance and it is also intended that they are readily available for women with bleeding disorders.

An illustrative case and a review on the dosing of recombinant factor VIIa in congenital factor XI deficiency

Recombinant activated factor VII (rFVIIa) has been used in a very limited number of patients with severe factor XI (FXI) deficiency. The dose and duration of treatment has varied greatly between these case reports. In a few of these cases there was also evidence of thrombotic complications. We present here a report on one additional patient with congenital FXI deficiency. For two major orthopaedic procedures in this patient we used rFVIIa as a single bolus dose followed by continuous infusion at a low rate. The data from these treatment episodes, together with those from a review of the published cases, lend support to the concept of using much lower doses than in haemophilia with inhibitors. A bolus dose of 20 microg kg(-1) and thereafter maintenance of the FVII activity at approximately 3 IU mL(-1) appears effective and safe.

Inhibitors to Factor XI in Patients With Severe Factor XI Deficiency

Factor XI (FXI) deficiency is a rare bleeding disorder that may arise from any of a number of missense, nonsense, splice site, insertion, and deletion mutations within the FXI gene. Severely affected patients are at considerable risk of developing inhibitors to FXI and, although spontaneous bleeding is uncommon in such patients, bleeding after surgery or trauma can be severe. As treatment with fresh frozen plasma (FFP) or FXI concentrates is ineffective in patients with inhibitors, other therapies must be sought. Traditionally, such patients have been treated with various agents and methods, including plasma exchange, cyclophosphamide, intravenous immunoglobulin, and prothrombin complex concentrates. However, emerging data indicate that recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark) may also be effective in FXI deficiency with inhibitors. Further work is required to determine the optimal dosing schedules of the agent in this indication.

Challenges in the Therapeutic Use of a “So-Called” Universal Hemostatic Agent: Recombinant Factor VIIa

Recombinant factor VIIa (rFVIIa) was developed in the early 1990s to provide “bypassing” hemostatic therapy for hemophilia A and B patients with inhibitors. More recently, it has been licensed for use in patients with inherited deficiency of factor VII. Since it was licensed for use in hemophilia with inhibitors in the US, Europe, and other countries for these specific indications, it has been used selectively but in a wide array of clinical settings for uncontrolled hemorrhage in individuals without an inherited bleeding disorder. Many of these uses have been described in the medical literature as case reports or small, uncontrolled series. Several randomized clinical trials (RCT) for these “off-label” medical uses have been published in recent months and will serve as the focus of this review. In particular, a review of an RCT for spontaneous intracranial hemorrhage that has demonstrated clinical efficacy in reducing both mortality and volume of central nervous system hemorrhage will be offered. A brief discussion of hypothesized physiologic mechanisms of supraphysiologic doses of rFVIIa will introduce the clinical discussion of these broad off-label uses. Since rFVIIa is a very expensive therapy, possible strategies for optimizing its use in the these settings will be presented.