Safety and efficacy of factor XI (FXI) concentrate use in patients with FXI deficiency: a single‐centre experience of 19 years

Diagnosis and management of factor XI alloinhibitors in patients with congenital factor XI deficiency-A large single-centre experience

INTRODUCTION

Factor (F) XI deficiency is an inherited bleeding disorder with increased prevalence in Ashkenazi Jews where it is mainly caused by two variants, p.Glu135* (type II, leading to a null allele) and p.Phe301Leu (type III, missense variant). Inhibitor development is rare, and only seen in severe FXI deficiency (<20 IU/dL) upon exposure to plasma-based products. We report our experience of a large cohort of patients with severe FXI deficiency, including seven patients who developed FXI alloinhibitors, their presentation, natural history and subsequent perioperative management.

METHODS

A single-centre retrospective database review of patients with FXI deficiency, including those who have subsequently developed inhibitors, and extraction of clinical, laboratory and genotype data, including operative management records.

RESULTS

A total of 682 patients were identified with FXI deficiency, of whom 113 had FXI < 20 IU/dL and 42 had FXI ≤ 1 IU/dL. Factor XI inhibitors were seen in seven patients, six of whom were homozygous for the type II variant (prevalence of inhibitor with this genotype of 30%, risk of inhibitor upon plasma exposure 50%). FXI inhibitors were not seen, despite similar exposures, in patients with other genotypes. No alteration in bleeding phenotype occurred after inhibitor development and subsequent surgery was managed on 13 occasions with recombinant factor VIIa (rFVIIa), including low doses (15-30 µg/kg), with good haemostasis. The inhibitor spontaneously disappeared in four of seven patients over 1-22 years.

CONCLUSION

FXI inhibitors were only observed in severe FXI deficient patients homozygous for p.Glu135* (null allele) upon plasma or FXI concentrate exposure, with a 30% prevalence. The bleeding phenotype was not altered and inhibitors may disappear with time. Adequate haemostasis in the perioperative setting is achievable with low doses of rFVIIa.

Factor XI and coagulation. Factor XI inhibitors - antithrombotic perspectives

Factor XI is a zymogen with an important role in the coagulation cascade. It is activated by FXII, thrombin and or it can be autoactivated. It has a prothrombotic effect after being activated by thrombin, but also through its antifibrinolytic action, stabilizing the formed clot. Hereditary deficiency of FXI causes haemophilia C - a disease manifested by an usually provoked, small to moderate mucosal bleeding. People with severe FXI deficiency have a low risk of thrombotic events. Conversely, increased FXI values have been found to be associated with increased risk of venous thromboembolism and ischemic stroke. Lowering serum FXI levels has become a treatment target for the prevention of thrombotic events. New pharmacological agents - FXI inhibitors - have been investigated in phase II clinical trials, with promising results in terms of efficacy and safety in the prevention of thrombotic events. FXI inhibitors are emerging as new anticoagulant agents with broad indication prospects beyond direct oral anticoagulants and vitamin K antagonists.

The foundation for investigating factor XI as a target for inhibition in human cardiovascular disease

Anticoagulant therapy is a mainstay in the management of patients with cardiovascular disease and related conditions characterized by a heightened risk for thrombosis. Acute coronary syndrome, chronic coronary syndrome, ischemic stroke, and atrial fibrillation are the most common. In addition to their proclivity for thrombosis, each of these four conditions is also characterized by local and systemic inflammation, endothelial/endocardial injury and dysfunction, oxidative stress, impaired tissue-level reparative capabilities, and immune dysregulation that plays a critical role in linking molecular events, environmental triggers, and phenotypic expressions. Knowing that cardiovascular disease and thrombosis are complex and dynamic, can the scientific community identify a common pathway or specific point of interface susceptible to pharmacological inhibition or alteration that is likely to be safe and effective? The contact factors of coagulation may represent the proverbial "sweet spot" and are worthy of investigation. The following review provides a summary of the fundamental biochemistry of factor XI, its biological activity in thrombosis, inflammation, and angiogenesis, new targeting drugs, and a pragmatic approach to managing hemostatic requirements in clinical trials and possibly day-to-day patient care in the future.

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.

Challenges of antithrombotic therapy in the management of cardiovascular disease in patients with inherited bleeding disorders: A single-centre experience

INTRODUCTION

Cardiovascular events in patients with inherited bleeding disorders are challenging to manage. The risk of bleeding secondary to antithrombotic treatment must be balanced against the risk of thrombosis secondary to haemostatic therapy.

METHODS

Patients with inherited bleeding disorders with coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI) or atrial fibrillation (AF) from a single centre (2010-2018) are included.

RESULTS

A total of 11 patients undergoing CABG (n = 3), PCI (n = 5) or with AF (n = 3) and a diagnosis of haemophilia A (n = 8), haemophilia B (n = 1), factor XI deficiency (n = 1) and von Willebrand disease (n = 1) managed by a multidisciplinary team are reported. In patients undergoing CABG, factor levels were normalized for 7-10 days with trough levels of 70-80% with severe patients continuing high-dose factor prophylaxis (trough 20-30%) three weeks post-operatively with daily aspirin. In a patient with mild haemophilia A and an inhibitor, recombinant factor VIIa dosing was monitored with thromboelastometry. For PCI, a 3rd-generation drug-eluting stent with one month of dual antiplatelet therapy in addition to high-dose prophylaxis as needed was preferred. Patients with AF and severe haemophilia did not receive antithrombotic treatment, and a thrombin generation assay was used to guide heparin dosing in mild haemophilia.

CONCLUSION

Our experience demonstrates the importance of interdisciplinary communication to identify strategies that decrease the risk of bleeding and thrombosis. The use of extended, increased intensity prophylaxis facilitated antiplatelet therapy. Global assays may help balance the intensity of haemostatic and antithrombotic treatment.

The clinical management of factor XI deficiency in pregnant women

INTRODUCTION

Factor XI (FXI) deficiency is associated with highly variable bleeding, including excessive gynecologic and obstetrical bleeding. Since approximately 20% of FXI-deficient women will experience pregnancy-related bleeding, careful planning and knowledge of appropriate hemostatic management is pivotal for their care.

AREAS COVERED

In this manuscript, authors present our current understanding of the role of FXI in hemostasis, the nature of the bleeding phenotype caused by its deficiency, and the impact of deficiency on obstetrical care. The authors searched PubMed with the terms, 'factor XI', 'factor XI deficiency', 'women', 'pregnancy', and 'obstetrics' to identify literature on these topics. Expectations of pregnancy-related complications in women with FXI deficiency, including antepartum, abortion-related, and postpartum bleeding, as well as bleeding associated with regional anesthesia are discussed. Recommendations for the care of these women are considered, including guidance for management of prophylactic care and acute bleeding.

EXPERT COMMENTARY

FXI deficiency results in a bleeding diathesis in some, but not all, patients, making treatment decisions and clinical management challenging. Currently available laboratory assays are not particularly useful for distinguishing patients with FXI deficiency who are prone to bleeding from those who are not. There is a need for alternative testing strategies to address this limitation.

Recent advances in use of fresh frozen plasma, cryoprecipitate, immunoglobulins, and clotting factors for transfusion support in patients with hematologic disease

Hematologic diseases include a broad range of acquired and congenital disorders, many of which affect plasma proteins that control hemostasis and immune responses. Therapeutic interventions for these disorders include transfusion of plasma, cryoprecipitate, immunoglobulins, or convalescent plasma-containing therapeutic antibodies from patients recovering from infectious diseases, as well as concentrated pro- or anticoagulant factors. This review will focus on recent advances in the uses of plasma and its derivatives for patients with acquired and congenital hematologic disorders.

Treatment of rare factor deficiencies other than hemophilia

The deficiency of fibrinogen, prothrombin, factor V (FV), FVII, FVIII, FIX, FX, FXI, and FXIII, called rare coagulation disorders (RCDs), may result in coagulopathies leading to spontaneous or posttrauma and postsurgery hemorrhages. RCDs are characterized by a wide variety of symptoms, from mild to severe, which can vary significantly from 1 disease to another and from 1 patient to another. The most typical symptoms of all RCDs are mucosal bleedings and bleeding at the time of invasive procedures, whereas other life-threatening symptoms such as central nervous system bleeding and hemarthroses are mostly present only in some deficiencies (afibrinogenemia, FX, and FXIII). At variance with hemophilia A and B and von Willebrand disease, RCDs are much less prevalent, ranging from 1 case in 500 000 to 1 in 2 million in the general population. Their clinical heterogeneity associated with the low number of patients has led to a delay in the development of appropriate therapies. Indeed, a similar heterogeneity can also be found in the treatment products available, ranging from the specific recombinant proteins to treat FVII- and FXIII-deficient patients to the complete absence of specific products to treat patients with FII or FV deficiencies, for whom prothrombin complex concentrates or fresh frozen plasma are, to date, the only option. The recent development of novel hemostatic approaches for hemophilia, such as the use of nonsubstitutive therapy as RNA interference, anti-tissue factor pathway inhibitor, and the gene therapy aimed at improving the patient's quality of life may also have an important role in the treatment of patients with RCDs in the future.