Early prophylaxis/FVIII tolerization regimen that avoids immunological danger signals is still effective in minimizing FVIII inhibitor developments in previously untreated patients - long-term follow-up and continuing experience

A Cross-sectional Analysis of Treatment in PUPs in 2021 in Germany - First Data from the GEPHARD Study Group

OBJECTIVES

 Initial treatment in patients with haemophilia remains challenging. The choice of therapy, timing, dose and frequency have been and are still under intense debate. New treatment options like novel factor concentrates and non-factor therapies broaden the discussion.

DESIGN

 The German Paediatric Haemophilia Research Database (GEPHARD) is a multicentre prospective observational study including children and adolescents with haemophilia A or B (FVIII or FIX levels <25 IU/dL) in a German treatment centre after January 1st, 2017. A cross-sectional analysis was performed in June 2021.

RESULTS

 249 children and adolescents from 22 participating centres in Germany were analysed in this cross-sectional analysis. 203 patients suffered from haemophilia A (PwHA) and 46 from haemophilia B (PwHB). The median age at diagnosis for Pw severe HA or HB was 6 or 2 months, the median age at analysis was 33 or 35 months for Pw severe HA or B, respectively. 117 Pw severe HA received treatment, including plasma derived concentrates (n = 43), standard recombinant concentrates (n = 23), extended half live concentrates (n = 33) and non-replacement therapies (n = 18). For Pw severe HB, plasma derived concentrates (n = 3), standard recombinant concentrates (n = 8) and extended half live concentrates (n = 14) were used. Current inhibitors were reported in 16 PwHA and 1 PwHB.

CONCLUSIONS

 GEPHARD was successfully established as a national cohort for newly diagnosed PwH in Germany. Epidemiological and treatment data were presented. Longitudinal analyses of this growing cohort will allow to value treatment strategies and their outcome in the evolving treatment landscape.

Incidence of inhibitor development in PUPs with severe Haemophilia A in the CEE region between 2005 and 2015

INTRODUCTION

This study analyses real-world data on 144 previously untreated patients (PUPs) with severe Haemophilia A, from seven countries in Central and Eastern Europe (CEE: Bulgaria, Croatia, Czech Republic, Hungary, Latvia, Serbia, and Slovenia), over a period of 11 years. It analyses the risk factors associated with development of inhibitors to factor VIII concentrates.

METHODS

Cox proportional hazard models were used to estimate the hazard risk of factors possibly influencing the development of inhibitors. Patients were followed for up to 100 exposure days (EDs).

RESULTS

Cumulative inhibitor incidence at the time of 100 EDs was 18.7%, slightly lower than the 25-35% incidence reported in most studies. Of PUPs who developed inhibitors, a majority (56%) developed them within the first 20 EDs and 88% by the 50th ED. FVIII class (recombinant or plasma-derived) did not influence the inhibitors' incidence rate (p = 0.64). We found a significant protective effect of prophylaxis compared to on-demand treatment (p = 0.003). PUPs who had an intensive peak treatment during the first 50 EDs were at significantly higher risk for inhibitor development (HR (95% CI) 5.3 (2.3-12.5), p < 0.001).

CONCLUSION

Inhibitors are and will continue to be the most significant complication of haemophilia treatment with factor concentrates. This is particularly true for haemophilia A. In our cohort, we were able to show that the treatment regimen used during first 50EDs influenced significantly the inhibitor risk, but the class of the factor concentrate did not play an important role. Real world data will remain one of the important resources for improving our knowledge of haemophilia.

Inhibitors-Recent insights

The development of inhibitory antibodies to therapeutic factor VIII (FVIII) in haemophilia A (HA) patients is the major complication in treatment/prevention of haemorrhages. The reasons some HA patients develop inhibitors while others do not remain unclear. This review briefly summarizes our understanding of anti-FVIII immune responses, the roles of T cells, both effector and regulatory, and generally discusses the interplay between FVIII and the immune system, both in factor replacement therapy and gene therapy, with some comparisons to factor IX and haemophilia B therapies. Notably, we propose that the prevailing observed active tolerance to FVIII in both HA and non-HA individuals rests to greater or lesser extents on peripherally induced immune tolerance. We also propose that the immune systems of inhibitor-negative HA patients do not merely ignore therapeutic FVIII, but rather have immunologically assessed and actively tolerized the patients to exogenous FVIII. Induction of such peripheral immune tolerance may further be triggered in HA patients who failed to tolerize upon initial FVIII exposure by 'appropriate' stimulation of their immune system, eg by immune tolerance induction therapy via intensive FVIII therapy, by oral administration of FVIII, by cellular therapies or by gene therapy directed to immuno-tolerogenic sites such as the liver.

[Origin and nature of the neutralizing immune response against therapeutic factor VIII]

The use of therapeutic proteins induces in some patients the appearance of neutralizing antibodies. This is the case of pro-coagulant factor VIII (FVIII) used in patients with hemophilia A. Several parameters related to the protein itself, to the type of pathology or to the patients, condition the immunogenicity of a therapeutic protein. Understanding these parameters would help to anticipate or prevent the development of neutralizing antibodies. In the case of FVIII, we propose that the development of neutralizing antibodies does not result from an unpredicted immune response but rather from the inability of the patient's organism to develop an anti-inflammatory or regulatory response.

Hemophilia A with inhibitor: Immune tolerance induction (ITI) in the mirror of time

Inhibitor (neutralizing antibodies) development remains the most significant complication in patients with severe congenital hemophilia A receiving exogenous factor VIII (FVIII). Although our understanding of the pathophysiology of inhibitor development has advanced, the knowledge gained has not yet translated into a robust decline in incidence, with the overall risk remaining at ∼30%. Immune Tolerance Induction (ITI) is the only current method to successfully eradicate an inhibitor and achieve long-term tolerance. Although current practice utilizes a wide variety of ITI regimens, identification of an optimal regimen has not emerged. Over the last decade, the number of replacement products available in hemophilia has greatly expanded. The cumulative evidence with each product for use in ITI is often lacking. Most recently emicizumab, a humanized monoclonal bi-specific antibody that substitutes for the scaffolding effect of FVIIIa was approved; this agent prevents bleeding in both inhibitor and non-inhibitor patients. The use of emicizumab will bring about a new era in care that will require clinicians to challenge current practice paradigms including use and administration of ITI. This review will summarize the main clinical ITI data and practices for patients with severe congenital hemophilia A with inhibitors (CHAwI) over the last four decades and will highlight current studies in the field, with attention to open questions.

Management of hydrocephalus in infants with severe hemophilia A: report of 2 cases

The authors report on the clinical course of two infants with severe hemophilia A (HA) and concomitant progressive hydrocephalus that required management with a ventriculoperitoneal shunt. The first child, with known HA, presented with a spontaneous intracranial hemorrhage and acquired hydrocephalus. He underwent cerebrospinal fluid diversion with a temporary external ventricular drain, followed by placement of a ventriculoperitoneal shunt. The second child had hydrocephalus secondary to a Dandy-Walker malformation and was diagnosed with severe HA during preoperative evaluation. He underwent placement of a ventriculoperitoneal shunt after progression of the hydrocephalus. The authors also review the treatment of hydrocephalus in patients with HA and describe the perioperative protocols used in their two cases. Treatment of hydrocephalus in infants with HA requires unique perioperative management to avoid complications.

Pathogenic immune response to therapeutic factor VIII: exacerbated response or failed induction of tolerance?

Therapeutic factor VIII is highly immunogenic. Despite intensive research in the last decades, the reasons why 5-30% of patients with hemophilia A (of all severities) develop inhibitory anti-factor VIII antibodies (inhibitors) following replacement therapy remain an enigma. Under physiological conditions, endogenous factor VIII is recognized by the immune system. Likewise, numerous observations indicate that, in hemophilia A patients without inhibitors, exogenous therapeutic factor VIII is immunologically assessed and tolerated. A large part of the research on the immunogenicity of therapeutic factor VIII is attempting to identify the ‘danger signals’ that act as adjuvants to the deleterious anti-factor VIII immune responses. However, several of the inflammatory assaults concomitant to factor VIII administration initially hypothesized as potential sources of danger signals (e.g., bleeding, infection, and vaccination) have been disproved to be such signals. Conversely, recent evidence suggests that cells from inhibitor-negative patients are able to activate anti-inflammatory and tolerogenic mechanisms required to suppress deleterious immune responses, while cells from inhibitor-positive patients are not. Based on the available observations, we propose a model in which all hemophilia A patients develop anti-factor VIII immune responses during replacement therapy irrespective of associated danger signals. We further postulate that the onset of clinically relevant factor VIII inhibitors results from an inability to develop counteractive tolerogenic responses to exogenous factor VIII rather than from an exacerbated activation of the immune system at the time of factor VIII administration. A better understanding of the pathogenesis of neutralizing anti-factor VIII antibodies will have repercussions on the clinical management of patients and highlight new strategies to achieve active immune tolerance to therapeutic factor VIII.

How I approach: Previously untreated patients with severe congenital hemophilia A

Previously untreated patients with severe hemophilia A are a vulnerable population at risk for severe bleeding which is currently managed with exogenous clotting factor replacement. The primary burden of current treatment is high-titer inhibitor development. Evolving data on current treatment products as well as emerging therapeutics may inform treatment decisions to prevent bleeding and inhibitor formation. Considerations for diagnosis, education, and shared decision-making related to product choice and treatment regimen are discussed.

Modified Primary Prophylaxis in Previously Untreated Patients With Severe Hemophilia A in Iran

BACKGROUND

Recently the low-dose tailoring method of primary prophylaxis has been introduced for previously untreated patients with hemophilia A.

OBJECTIVE

To evaluate the efficacy and safety of low-dose tailoring method of primary prophylaxis in previously untreated patients with severe hemophilia A.

MATERIALS AND METHODS

In this pre-post interventional study, 33 patients with severe hemophilia A who were previously untreated and affiliated to universities in the capital city and southern Iran were evaluated during 2014 to 2015. Modified primary continuous prophylaxis was used for patients with age below 3 years old, after first and before the second episodes of obvious clinical bleeding in large joints or large soft tissue hematoma or large amount of bleeding. Prophylaxis was started by 25 IU/kg once per week and increased to twice or 3 times a week according to defined bleeding events.

RESULTS

The median age at diagnosis and age of starting prophylaxis were: 4 months (at birth, 22 mo) and 12 months (1 to 35 mo), respectively. Mean annual bleeding rate of patients after prophylaxis was 1.08±2.21 episodes per year. None of the patients had inhibitors before therapy. Inhibitor was present in 5 patients (15.1%) after prophylaxis.

CONCLUSIONS

It seems that modified primary continuous prophylaxis has been successful in reducing bleeding episodes in children with severe hemophilia A and in the texture of lower cost it can improve quality of life of these patients, especially in developing countries where financial resources are limited.

Plasma-derived versus recombinant factor concentrates in PUPs: a never ending debate?

Inhibitor development in haemophilia is a serious complication to treatment with factor concentrates. Since the advent of more pure products, especially developed using recombinant DNA technology, some studies have shown an increased incidence of inhibitors in previously untreated patients (PUPs) receiving recombinant products whereas plasma-derived concentrates sometimes have been claimed to have a protective role, probably due to the content of von Willebrand factor (VWF). In fact, experiments indicate that the VWF may block uptake of factor VIII into macrophages for further processing to the immune system. Also, a competition between VWF and inhibitor binding to the C2 domain of factor VIII has been suggested. Recently, large cohort and surveillance studies have created a vigorous debate about the role of product class for inhibitor development as results have been conflicting. The only randomised prospective study, the SIPPET study, was published in 2016, and substantiated previous reports claiming that plasma derived concentrates give less inhibitors in patients with severe haemophilia A, previously not exposed to factor VIII. The debate will continue.

Different impact of factor VIII products on inhibitor development?

Inhibitors are the most serious side effect of haemophilia treatment; they occur in 25–30 % of all patients with severe haemophilia A. Over the last 2 decades, conflicting data on the impact of clotting products have been published.

Due to small studies of selected cases, appreciation of the impact of any particular product has been difficult. Moreover, the emphasis on inhibitor testing has led to increased detection of low-titre inhibitors (to >10 %), while the percentage of high-titre inhibitors is still around 20 %.

Other non-genetic risk factors, such as dosing and intensive treatment, are able to increase individual inhibitor risk. Early prophylaxis might reduce inhibitor risk. Well-defined large PUP studies including products should be considered. This can only be achieved in collaboration with all stakeholders.

In conclusion, while the impact of FVIII products on inhibitor development is large, presently the actual impact of any specific product is unclear.

Inhibitor development in previously untreated patients with severe haemophilia A: a nationwide multicentre study in Finland

INTRODUCTION

Currently the most serious treatment complication of haemophilia is the inhibitor development (ID), i.e. neutralizing antibody development.

AIM

This nationwide multicentre study in Finland evaluated the incidence and risk factors of ID in previously untreated patients (PUPs) with severe haemophilia A (FVIII:C < 0.01 IU mL(-1) ).

METHODS

We enrolled all PUPs (N = 62) born between June 1994 and May 2013 with at least 75 exposure days (EDs) to screen ID during follow-up extending to September 2013.

RESULTS

Thirteen ID (21% of 62) occurred; 10 (16% of 62) with high titre. Fifty-one patients (82%) were on primary prophylaxis (regular prophylaxis before the age of 2 and before the first joint bleed) from the median age of 11.4 months, 90% via a central venous access device. The initial product was rFVIII in 63% and pd-FVIII in 37%, moreover in 24% pd-FVIII was switched to rFVIII concentrate during the 75 EDs. Non-transient inhibitors developed in 9/51 (17.6%; 13.7% high titre) children with primary and in 4/11 (36.4%; 27.3% high titre) patients with secondary prophylaxis (P = 0.24). Overall, 74% had a high-risk genotype similarly distributed among the prophylaxis groups. The history of a major bleed enhanced ID (aHR, 4.0; 95% CI, 1.2-13.7), whereas FVIII treatment intensity or source and early implantation of ports did not increase ID risk.

CONCLUSION

The cumulative incidence of ID was low notwithstanding prevalent high-risk mutations. Despite patient-related risk factors, our management involving early intensive primary prophylaxis via ports helps to prevent bleeds and lower the incidence of inhibitors.

Non-genetic risk factors and their influence on the management of patients in the clinic

The development of inhibitors is the most serious iatrogenic complication affecting patients with haemophilia. This complication is associated with impaired vital or functional prognosis, reduced quality of life and increased cost of treatment. The reasons why some patients develop antibodies to factor replacement and others do not remain unclear. It is however clear that inhibitor development results from a complex multifactorial interaction between genetic and non-genetic risk factors. Environmental influences implicated in increasing the risk of inhibitor formation can be viewed as modifiable risk factors. Therefore, identification of the non-genetic risk factors may offer the possibility of personalising haemophilia therapy by modifying treatment strategies in high-risk patients in the critical early phase of factor VIII exposure. In this article, we review the non-genetic factors reported as well as the potential impact of danger signals and the different scores for inhibitor development risk stratification.

The role of previously untreated patient studies in understanding the development of FVIII inhibitors

Development of inhibitors against factor VIII (FVIII), the major complication of haemophilia A treatment today, is influenced by multiple factors. Genetic (F8 mutation, family history, ethnicity, polymorphisms in immune modulating genes) and non-genetic (intensive exposure to FVIII, presence of pro-inflammatory signals as might occur with large bleeds, infections, surgery, or other immune stimulants [e.g. vaccines]) risk factors as well as their complex inter-relationships contribute to the inhibitor risk profile of haemophilia patients, particularly in the previously untreated patient (PUP) population. Studies in PUPs have been fundamental to furthering the understanding of FVIII inhibitor development, as well as discovering previously unappreciated risk factors. The multi-factorial nature of inhibitor development makes it difficult to ascertain the contribution of FVIII products in inhibitor development through individual PUP studies. Sufficiently powered studies of large cohorts may overcome these limitations but interpretations should be conducted cautiously. Proper design and implementation of PUP safety studies will become even more important with the introduction of new molecules, such as extended half-life or human cell-line derived FVIII that propose reduced immunogenicity. Despite these difficulties, carefully performed clinical studies in PUPs may provide important insights into the natural history of the immune response to FVIII and may suggest targets for intervention to reduce immunogenicity.

Immunogenicity of biologic agents in rheumatoid arthritis patients: lessons for clinical practice

Anti-drug antibodies (ADAbs) develop in up to a third of patients treated with biologic agents, with such immunogenicity being one of the main reasons for the loss of efficacy observed in an important proportion of patients treated with such agents. The appearance of ADAbs has consequences in terms of efficacy and tolerance of the biodrug: the development of ADAbs is associated with a poorer clinical response and with an increased risk of adverse effects. Formation of ADAbs has been observed with all biologic DMARDs, but anti-TNF agent mAbs appear to be the largest contributors, independent of humanization of the antibody. ADAb identification is technically difficult and not standardized, partly explaining important variations between published studies. A variety of factors can influence the risk of ADAb appearance, some of which are linked to the treatment strategy, such as the combination with synthetic DMARDs or the rhythm of administration of the biodrug, whereas other factors are dependent on the patient, such as the level of inflammation at onset or body weight. The detection of these antibodies and/or the dosage of the biologic agent itself could have consequences for the bedside practice of clinicians and should be well understood. This review of the literature proposes an overview of the data published on the subject to help clinicians manage the biodrugs according to these new concepts.

Rapid acquisition of immunologic tolerance to factor VIII and disappearance of anti-factor VIII IgG4 after prophylactic therapy in a hemophilia A patient with high-titer factor VIII inhibitor

We report an 11-month-old boy with severe hemophilia A who had regular exposure to factor VIII (FVIII) intended to reduce the risk of developing an inhibitor. He developed a high-titer inhibitor (peak titer 19 BU) that disappeared within 6 weeks of starting immune tolerance induction (ITI). Anti-FVIII IgG4 peaked briefly compared with anti-FVIII IgG1 and the Bethesda titer. Neither rapid resolution of an inhibitor after prophylaxis nor this behavior of anti-FVIII IgG4 has been previously reported. Transient anti-FVIII IgG4 may be a marker of an attenuated anti-FVIII response induced by prophylactic FVIII therapy.

The growing number of hemophilia registries: Quantity vs. quality

Registries for rare diseases provide a tool for obtaining an overview of the clinical situation and can be used to discover points of improvement and to monitor long-term safety. Registries could also become a powerful tool to provide supporting information for marketing authorization. There is an urgent need for a pan-European or global strategy that supports consistent data. Therefore, transparency in data collection, harmonization of the database structures, and the convergence of scientific approaches are required.

Managing haemophilia for life: 4th Haemophilia Global Summit

The 4th Haemophilia Global Summit was held in Potsdam, Germany, in September 2013 and brought together an international faculty of haemophilia experts and delegates from multidisciplinary backgrounds. The programme was designed by an independent Scientific Steering Committee of haemophilia experts and explored global perspectives in haemophilia care, discussing practical approaches to the optimal management of haemophilia now and in the future. The topics outlined in this supplement were selected by the Scientific Steering Committee for their relevance and potential to influence haemophilia care globally. In this supplement from the meeting, Jan Astermark reviews current understanding of risk factors for the development of inhibitory antibodies and discusses whether this risk can be modulated and minimized. Factors key to the improvement of joint health in people with haemophilia are explored, with Carlo Martinoli and Víctor Jiménez-Yuste discussing the utility of ultrasound for the early detection of haemophilic arthropathy. Other aspects of care necessary for the prevention and management of joint disease in people with haemophilia are outlined by Thomas Hilberg and Sébastian Lobet, who highlight the therapeutic benefits of physiotherapy and sports therapy. Riitta Lassila and Carlo-Federico Perno describe current knowledge surrounding the risk of transmission of infectious agents via clotting factor concentrates. Finally, different types of extended half-life technology are evaluated by Mike Laffan, with a focus on the practicalities and challenges associated with these products.

Current management of the hemophilic child: a demanding interlocutor. Quality of life and adequate cost-efficacy analysis

Hemophilias are the most known inherited bleeding disorders. The challenges in the management of hemophilic children are different from those in adults: prophylaxis regimen removed the hallmark of crippling disease with lifelong disabilities; individualized regimens are being implemented in order to overcome venous access problems. Presently, at least in high-income countries, advances in treatment of hemophilia resulted in continuous improvement of the patients' quality of life and life expectancy. Inhibitors remain the most severe complication of hemophilia therapy. The treatment' compliance is the key to achieve a successful management. The patient, his family, the medical and psychological team are the players of a comprehensive care system. The current management of hemophilic children is the example of huge resource investments enabling long-term benefits in particular quality of life as a primary objective of the healthcare process.

Intensity of factor VIII treatment and inhibitor development in children with severe hemophilia A: the RODIN study

High-dose intensive factor VIII treatment increases the risk for inhibitor development in patients with severe hemophilia A. In patients with severe hemophilia A, factor VIII prophylaxis decreases inhibitor risk, especially in patients with low-risk F8 mutations.

Issues in pediatric haemophilia care

The hemophilias are the most common X-linked inherited bleeding disorders. The challenges in children are different from that in adults and, If not properly managed, can lead to chronic disease and lifelong disabilities. Currently, inhibitors are the most severe complication and prophylaxis is emerging as the optimal preventive care strategy. Quality of life has become in the western countries the primary objective of the process of providing care, thus all the strategies (psychotherapy, physiotherapy, community life), not just the infusion of the missing factor, should be activated for the patient and family to give them the perception of being healthy.

Progress toward inducing immunologic tolerance to factor VIII

A major problem in treating hemophilia A patients with therapeutic factor VIII (FVIII) is that 20% to 30% of these patients produce neutralizing anti-FVIII antibodies. These antibodies block (inhibit) the procoagulant function of FVIII and thus are termed "inhibitors." The currently accepted clinical method to attempt to eliminate inhibitors is immune tolerance induction (ITI) via a protocol requiring intensive FVIII treatment until inhibitor titers drop. Although often successful, ITI is extremely costly and is less likely to succeed in patients with high-titer inhibitors. During the past decade, significant progress has been made in clarifying mechanisms of allo- and autoimmune responses to FVIII and in suppression of these responses. Animal model studies are suggesting novel, less costly methods to induce tolerance to FVIII. Complementary studies of anti-FVIII T-cell responses using blood samples from human donors are identifying immunodominant T-cell epitopes in FVIII and possible targets for tolerogenic efforts. Mechanistic experiments using human T-cell clones and lines are providing a clinically relevant counterpoint to the animal model studies. This review highlights recent progress toward the related goals of lowering the incidence of anti-FVIII immune responses and promoting durable, functional immune tolerance to FVIII in patients with an existing inhibitor.

Health technology assessment and haemophilia

Although the funding of rare diseases such as haemophilia in developing countries remains a low priority, pressures on the funding of haemophilia treatment are also emerging in developed economies affected by the global economic downturn and the other demands on health care budgets. This is leading advisory bodies and payers alike to explore the tools of Health Technology Assessment (HTAs) in deriving recommendations for reimbursement policies. In particular, the use of cost utility analysis (CUA) in deriving costs per quality adjusted life year (QALY) for different interventions is being used to rank interventions in order of priorities relative to a threshold cost per QALY. In these exercises, rare chronic disorders such as haemophilia emerge as particularly unattractive propositions for reimbursement, as the accepted methodology of deriving a CUA. For e.g. the use of prophylaxis in haemophilia leads to a range of costs/QALY which exceed the willingness to pay thresholds of most payers. In this commentary, we review the principles utilized in a recent systematic review of the use of haemophilia products carried out in Sweden as part of an HTA. We suggest that ranking haemophilia related interventions with the standard interventions of therapeutics and public health in CUA comparisons is inappropriate. Given that haemophilia treatment is a form of blood replacement therapy, we propose that such comparisons should be made with the interventions of mainstream blood transfusion. We suggest that unequivocally effective treatments such as haemophilia therapies should be assessed differently from mainstream interventions, that new methodologies are required for these kinds of diseases and that evidence of a societal willingness to support people with rare disorders needs to be recognized when reimbursement policies are developed.

Source and purity of factor VIII products as risk factors for inhibitor development in patients with hemophilia A

BACKGROUND

Inhibitor development is influenced by several factors and the type of factor VIII (FVIII) products may play a role.

OBJECTIVES

In order to explore such a role, we designed a cohort study whose novelty resides in the classification of products not only according to the source of FVIII (plasmatic, pd, or recombinant, r) but also to their degree of purity (expressed as specific activity).

PATIENTS/METHODS

Treatment data up to inhibitor development or 150 exposure days were collected in 377 patients with hemophilia A.

RESULTS

Inhibitors developed in 111 patients (29%; 96 high-responders, 25%). The cumulative incidence was progressively higher from patients treated with low/intermediate-purity pdFVIII compared with those treated with high-purity pd and rFVIII. The adjusted hazard ratio of inhibitor development was 4.9 with rFVIII and 2.0 with high-purity pdFVIII (95% CI, 2.9-8.3 and 1.1-4.0), taking as reference low/intermediate-purity pdFVIII. There was no difference in the frequency of inhibitor testing between treatment groups. Sensitivity analyses (in patients who never switched product type, previously untreated patients, those treated on-demand and those with high-risk F8 mutations) confirmed an increased inhibitor risk with rFVIII and high-purity pdFVIII.

CONCLUSIONS

This study shows that the degree of purity of FVIII products influences inhibitor development independently from other risk factors, and emphasizes that differences exist within pdFVIII products.

A systematic overview of the first pasteurised VWF/FVIII medicinal product, Haemate P/ Humate -P: history and clinical performance

Patients with von Willebrand disease (VWD) and haemophilia A (HA) lack, to varying degrees, the von Willebrand factor (VWF) and coagulation factor VIII (FVIII) that are critical for normal haemostasis. These conditions in turn make patients prone to uncontrolled bleeding. Historically, patients with severe forms of VWD or HA were crippled before adulthood and their life expectancy was significantly reduced. Over the past decades, specific coagulation factor replacement therapies including Haemate P, have been developed to help patients achieve and maintain normal haemostasis. Haemate P is a human, plasma-derived VWF/FVIII medicinal product, which was first licensed in Germany in 1981 for the treatment of HA-associated bleeding. It has since then come to be accepted as the gold standard for both the treatment and prophylaxis of bleeding in VWD, especially in cases where desmopressin [1-deamino-8-D-arginine vasopressin (DDAVP)] has been ineffective. Haemate P was the first effectively virus-inactivated (pasteurisation: 60 degrees C for 10 h in aqueous solution) FVIII product, whereby the risk of potentially threatening infective complications of plasma-derived products was reduced. Haemate P was also shown to have a VWF multimer profile remarkably close to that of normal plasma. This bibliographic review presents previously unpublished clinical data of Haemate P, based upon internal clinical study reports of the proprietor, CSL Behring, in addition to data already presented in other publications. The data demonstrate a predictable and well-characterised pharmacokinetic profile, and a proven record of short- and long-term safety, while effectively correcting the haemostatic defects in VWD and HA. Recently available data have also shown Haemate P to be of haemostatic value in exceptional clinical circumstances including surgical interventions. By virtue of its plasma-derived combination of VWF and FVIII, in addition to its high VWF:FVIII content ratio (2.4:1), Haemate P is also associated with successful immune tolerance induction in those patients developing inhibitor antibodies. Although the theoretical risk of thromboembolic complications does exist while receiving Haemate P, as it does with any FVIII replacement therapy, the incidence of such complications has remained notably low. Given the robust data that have accumulated for the use of Haemate P, dosing recommendations are also described in this review; the recommendations are tailored to patient-specific contexts including baseline VWF and FVIII levels in plasma and the type of surgical intervention being undertaken. A wide variety of studies have also provided data on paediatric and geriatric populations, all of which have suggested that Haemate P can be safely and effectively used in a wide variety of clinical circumstances.