Immunoadsorption for coagulation factor inhibitors: a retrospective critical appraisal of 10 consecutive cases from a single institution

Antibodies against Noncatalytic B Subunit of Factor XIII Inhibit Activation of Factor XIII and Fibrin Crosslinking

BACKGROUND

 Coagulation factor XIII (FXIII) is a proenzyme of plasma transglutaminase. It comprises two catalytic A subunits (FXIII-A) and two carrier B subunits (FXIII-B). We previously reported that alloantibodies against FXIII-B could promote FXIII clearance in a patient with congenital FXIII-B deficiency who had received infusions of plasma-derived human FXIII (A2B2 heterotetramer).

OBJECTIVES

 We aimed to investigate whether anti-FXIII-B antibodies affect the catalytic function of FXIII.

METHODS

 FXIII activation and fibrin crosslinking were examined in the presence of patient plasma, isolated patient IgG, or rat anti-FXIII-B monoclonal antibodies.

RESULTS

 Alloantibody levels were increased by repeated infusions of plasma-derived A2B2 heterotetramer, which enhanced binding to the functionally important FXIII-B sushi domains. The patient plasma strongly inhibited cleavage of the FXIII-A activation peptide, amine incorporation, and fibrin crosslinking in normal plasma. Furthermore, anti-FXIII-B alloantibodies blocked the formation of the complex of FXIII-B with FXIII-A, and fibrinogen. Rat monoclonal antibodies against the 10th sushi domain of FXIII-B inhibited the incorporation of FXIII-B to fibrin, FXIII activation (i.e., cleavage of FXIII-A activation peptide), and ultimately fibrin crosslinking in normal plasma, independent of their effect on heterotetramer assembly with FXIII-A. Alloantibody binding to the A2B2 heterotetramer blocked the access of thrombin to the FXIII-A cleavage site, as indicated by the reaction of the alloantibodies to the A2B2 heterotetramer and FXIII-B, but not to FXIII-A.

CONCLUSION

 Anti-FXIII-B antibodies binding to the A2B2 heterotetramer and FXIII-B inhibited FXIII activation and its crosslinking function despite being directed against its noncatalytic subunit (FXIII-B).

Feasibility of therapeutic plasma exchange-based combination therapy in the treatment of acquired hemophilia A: A retrospective 6 case series

Poor availability and a lack of affordability of bypassing agents (recombinant activated factor VII and activated prothrombin complex concentrate) in west China prompted us to investigate an alternative cost-effective combination therapy. We aimed to explore the feasibility of therapeutic plasma exchange (TPE)-based combination therapy in the treatment of acquired hemophilia A (AHA).We retrospectively investigated the clinical features of AHA in 6 patients who were treated with a combination of TPE, corticosteroids, and rituximab in our department for 9 years between January, 2011 and December, 2019.We examined 1 male and 5 female patients. The median age at diagnosis of AHA was 51 years (18-66 years). In all patients, FVIII activity levels were low (median: 1.5%; 1-3%), FVIII inhibitor titers were high (median: 24.5 BU/mL; 13.2-48.6 BU/mL), and activated partial thromboplastin time was markedly prolonged (median: 99.4 s; 60.9-110.1 s). They underwent 2 to 8 cycles of plasma exchange and were given varying combinations of dexamethasone, methylprednisolone, prednisone, and rituximab. After TPE bleeding gradually stopped, and activated partial thromboplastin time decreased. After 3 months of treatment, FVIII inhibitors completely disappeared.TPE when combined with corticosteroids and rituximab, as adjunctive immunosuppressive agents, may be an effective and reliable treatment for AHA. When there is no alternative, intensive first-line treatment including TPE may be lifesaving.

Immunoadsorption for the Treatment of Acquired Hemophilia: New Observational Data, Systematic Review, and Meta-Analysis

The treatment of patients with acquired hemophilia is challenging due to life-threatening hemorrhages, delayed response, and adverse effects to immunosuppressive agents. Even though immunoadsorption (IA) rapidly removes autoantibodies against factor VIII, this intervention's effectiveness is still a matter of debate. We aimed to study important outcomes of IA as adjunctive treatment in patients with acquired hemophilia. We performed comprehensive literature searches in MEDLINE and EMBASE databases. Clinical and laboratory data of all patients treated in our institution were additionally included. Literature searching yielded 498 records, of which 10 studies describing 106 patients were finally included. The number of patients varied from 1 to 65, and patients' ages ranged between 14 and 89. Treatment criteria in most patients were (1) failed response to immunosuppressive treatment alone, and/or (2) uncontrollable bleeding episodes, and/or (3) high inhibitor titer. Methodological quality was moderate. The number of IA sessions varied from 1 to 24. Within our institution, 12 patients have been treated since 2002; median age was 76 years (range 34-86); median titer of factor VIII inhibitor was 20 Bethesda units (range 3-214). Pooled estimates, modeling a random-effect binominal distribution incorporating the Freeman-Tukey double arcsine transformation, were 86% in case of factor VIII recovery (95% confidence interval 76%-94%), 95% for reduction of factor VIII inhibitor (83%, 100%), and 7% in case of death (0%, 18%). Our data suggest that IA might be a beneficial adjunctive treatment in patients with high-risk acquired hemophilia, but future studies shall confirm this observation.

Acquired factor XIII deficiency: A review

Acquired factor XIII (FXIII) deficiency is a rare bleeding disorder that can manifest with spontaneous or delayed life-threatening hemorrhage. Causes of acquired deficiency include immune-mediated inhibition, as well as non-immune FXIII hyperconsumption or hyposynthesis. The occurrence of acquired FXIII deficiency can be idiopathic or may be associated with comorbidities, such as malignancies or autoimmune disorders. Recognition of acquired FXIII deficiency and its underlying cause is imperative, as treatment options vary depending on the etiology. Diagnosis requires quantitative FXIII testing in addition to supplemental inhibitor studies if the clinical situation suggests an immune-mediated pathophysiology. Treatment may involve FXIII replacement, antifibrinolytic administration, and/or inhibitor eradication. However, treatment targets and thresholds are undefined in acquired FXIII deficiency. This review will focus on the clinical characteristics, diagnostic issues and therapeutic options for both immune and non-immune acquired FXIII deficiency. Cases are described to illustrate the clinical features of acquired FXIII deficiency.

Alloantibodies against the B subunit of plasma factor XIII developed in its congenital deficiency

Factor XIII (FXIII) is a fibrin-stabilising factor consisting of catalytic A subunits (FXIII-A) and carrier B subunits (FXIII-B). FXIII-B prevents the fast clearance of FXIII-A from the circulation. Congenital FXIII-A deficiency is a rare bleeding disorder, and congenital FXIII-B deficiency is even rarer. Through our recent nationwide survey on “acquired haemophilia-like disease due to anti-FXIII autoantibodies,” we newly diagnosed severe congenital FXIII-B deficiency in a Japanese man. He developed thrombocytopenia and gingival bleedings at the age of 73, and his FXIII activity was as low as 10% of the normal. When he suddenly developed spontaneous intramuscular haematoma, the bleeding was arrested by infusing FXIII concentrates. However, his FXIII activity remained around 10% of the normal. At the age of 74, ELISA and western blotting assay unexpectedly revealed complete absence of FXIII-B in the patient’s plasma. A dot blot assay detected anti-FXIII-B alloantibodies for the first time in this disease, which could be attributed to the infusion of exogenous FXIII. He was found to be homozygous for a Japanese founder-effect mutation of F13B. Repeated infusions of exogenous FXIII for hemostasis increased anti-FXIII-B alloantibodies that resisted FXIII substitution. To the best knowledge of the authors, none of the remaining 10 reported cases of congenital FXIII-B deficiency developed alloantibodies to exogenous FXIII-B of plasma FXIII. An originally mild bleeding phenotype of severe congenital FXIII-B deficiency can be exaggerated by additional acquired conditions. Physicians should consider congenital FXIII-B deficiency when they encounter cases of unexplained bleeding disorders.

Therapeutic plasma exchange as part of multimodal treatment of acquired hemophilia in a patient with concurrent acute intracerebral bleed and pulmonary embolism

BACKGROUND

Autoantibodies against Factor VIII (FVIII) define the rare but life-threatening bleeding disorder acquired hemophilia A (AHA). Correction of FVIII deficiency and eradication of the factor inhibitor are the ultimate therapeutic goals in this disorder. Bypassing agents such as recombinant factor VIIa (rFVIIa) or FVIII inhibitor bypassing agent are often used to control coagulopathy before the inhibitor is eradicated. Bypassing agents carry a risk of thrombosis, however.

CASE REPORT

We report a patient with newly diagnosed AHA and thalamic bleed who additionally had active atrial fibrillation and developed a segmental pulmonary embolism, limiting tolerable rFVIIa dosage. This patient with very-high-risk brain bleed and concurrent thrombosis on bypass agent represented a significant management dilemma for which we successfully utilized therapeutic plasma exchange (TPE) to reduce the inhibitor titer.

RESULTS

FVIII inhibitor was undetectable and FVIII level was above the lower limit of normal within 12.5 days from starting TPE. While the patient ultimately died 24 days from admission for reasons unrelated to bleeding, his intracerebral hemorrhage was unchanged in size and no other bleeding morbidity was observed.

CONCLUSION

This patient achieved eradication of FVIII inhibitor and did not have bleed expansion while receiving multimodal therapy including corticosteroids, rituximab, and TPE. We discuss the periprocedural risks of TPE in an acquired hemophilia patient and our multiteam management of that risk.

A Hematological Menace: Multiple Venous Thrombosis Complicated by Acquired Factor VIII Deficiency

Patient: Male, 21

Final Diagnosis: Acquired Factor VIII Deficiency

Symptoms: Abdominal hematoma • DVT • life threatening bleeding

Medication: —

Clinical Procedure: Life saving medical therapy

Specialty: Hematology

Immunosuppressive agents in the treatment of inhibitors in congenital haemophilia A and B--a systematic literature review

The development of inhibitory antibodies to factor VIII (FVIII) or factor IX (FIX) in patients with haemophilia is a serious complication of treatment with coagulation factor concentrates. Antibodies develop in 10-15% of haemophilia A and in up to 5% of haemophilia B patients. Several strategies have been developed over the years to facilitate the eradication of inhibitors and reduce the cost. These include plasmapheresis and/or extracorporeal protein A absorption to remove the inhibitor from the plasma, and immunosuppression and/or immune modulation to suppress the production of inhibitory antibodies. Different immunosuppressive (IS) agents have been described with varying success. To evaluate the outcome of these agents, we performed a systematic literature review using the PubMed database. The total number of articles identified was 345; 299 papers were excluded leaving 46 papers to be included in the study. No randomised studies were identified, only case reports and case series. The most frequently used agents in the 46 case reports and cohort studies identified were cyclophosphamide and rituximab. All cases exposed to cyclophosphamide, rituximab and other IS agents had a complete success rate of 40-44%, 40-63% and 33-56%, respectively. However, the definition of success was not consistent among the studies. In conclusion, our review of the literature indicates that IS agents in combination with FVIII or FIX could be an option and may be cost-effective in many patients. The risk of adverse events seems to be relatively low. To fully explore the effect of IS agents, randomised studies are warranted.

Challenges and open issues in the management of acquired hemophilia A (AHA)

Acquired hemophilia A (AHA) is a rare autoimmune bleeding disorder caused by antibodies which neutralize the function of factor VIII (FVIII). The disease presents a complex clinical challenge to the treating Physicians and Hematologists. As the disease is associated with high mortality, prompt management is necessary. Early recognition, quick diagnosis and timely referral to a specialized center are important for better management of these patients. The different clinical manifestations, underlying pathology, inhibitor kinetics and the associated age related comorbidities do not allow extrapolation of the treatment protocols of congenital hemophilia to AHA. The basic strategies of the management of AHA patients involve maintaining hemostasis, suppression or eradication of antibodies, diagnosis and treatment of underlying pathology and avoid treatment related complications like thrombosis. The efficiency of hemostatic agents which are generally used to treat AHA is unpredictable. Due to the rarity of the disease, there are no randomized clinical trials on the management of this disorder and thus the expertise and experience of the treating Physicians' guide treatment strategies.

A child with acquired factor XIII deficiency: case report and literature review

Factor XIII (FXIII) deficiency is a rare bleeding disorder, which can result in life threatening hemorrhage. Rarer still is acquired FXIII deficiency, in which the disorder is due to autoantibodies that inhibit the factor. To describe one of the youngest reported patients with this condition. To discuss the challenges we encountered in monitoring response with the available assays. To review the literature and provide a review of all acquired FXIII cases. We present the case of our patient, a 9-year-old girl with acquired FXIII deficiency. We present a comprehensive review of all acquired FXIII deficiency cases reported globally in English, with focus on clinical presentation, diagnostic assays, treatment and prognosis. There is no current standard for therapy and measuring response to therapy can be complicated by limitations of assays in the presence of inhibitors. Clinicians should be aware of acquired FXIII deficiency as a potentially life threatening bleeding disorder even in young children. The case presented illustrates a young patient with acquired FXIII deficiency with a good clinical response to cryoprecipitate and difficulty in hemostasis monitoring utilizing clinically available assays.

Recombinant factor XIII: a safe and novel treatment for congenital factor XIII deficiency

Congenital factor XIII (FXIII) deficiency is a rare, autosomal-recessive disorder, with most patients having an A-subunit (FXIII-A) deficiency. Patients experience life-threatening bleeds, impaired wound healing, and spontaneous abortions. In many countries, only plasma or cryoprecipitate treatments are available, but these carry a risk for allergic reactions and infection with blood-borne pathogens. The present study was a multinational, open-label, single-arm, phase 3 prophylaxis trial evaluating the efficacy and safety of a novel recombinant FXIII (rFXIII) in congenital FXIII-A subunit deficiency. Forty-one patients ≥ 6 years of age (mean, 26.4; range, 7-60) with congenital FXIII-A subunit deficiency were enrolled. Throughout the rFXIII prophylaxis, only 5 bleeding episodes (all trauma induced) in 4 patients were treated with FXIII-containing products. The crude mean bleeding rate was significantly lower than the historic bleeding rate (0.138 vs 2.91 bleeds/patient/year, respectively) for on-demand treatment. Transient, non-neutralizing, low-titer anti-rFXIII Abs developed in 4 patients, none of whom experienced allergic reactions, any bleeds requiring treatment, or changes in FXIII pharmacokinetics during the trial or follow-up. These non-neutralizing Abs declined below detection limits in all 4 patients despite further exposure to rFXIII or other FXIII-containing products. We conclude that rFXIII is safe and effective in preventing bleeding episodes in patients with congenital FXIII-A subunit deficiency. This study is registered at http://www..clinicaltrials.gov as number NCT00713648.

Immune tolerance induction in haemophilia: evidence and the way forward

Given the inhibitor-associated morbidity resulting from limited effective treatment options, antibody eradication is the ultimate goal of inhibitor management. The only clinically proven strategy for achieving antigen-specific tolerance to factor VIII is immune tolerance induction (ITI). First reported over 30 years ago, much of our current knowledge about ITI in haemophilia A and B was derived from small cohort studies and retrospective national and international ITI registries. More recently, prospective randomised ITI trials have been designed and initiated to answer outstanding questions related to the optimisation of current therapeutic strategy in haemophilia A. However, due to the low incidence of inhibitor development in haemophilia B compared to haemophilia A, there are few comparable data from which to develop a useful evidence-based approach to the prevention and eradication of FIX inhibitors. The lack of an effective strategy is particularly problematic given the even greater morbidity associated with the almost unique occurrence of allergic and anaphylactic reactions that often herald FIX antibody development, and further complicates attempts to eradicate FIX inhibitors. Ultimately, successful inhibitor prevention and eradication strategies for both diseases will emerge from the clinical translation of our evolving knowledge of immune stimulation and tolerance. This paper will discuss our current understanding of immune tolerance outcome and outcome predictors for haemophilia A and B; it will also review the current consensus recommendations for ITI, as well as the emerging scientific body of immunological knowledge that may significantly impact the therapeutic and preventative strategies of the future.

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.

Factor VIII inhibitors: a 50-year perspective

Inhibitors of factor VIII (FVIII) have been studied for more than 50 years, but diagnostic and therapeutic challenges remain. To describe the features that distinguish alloantibodies from autoantibodies, list predisposing factors, and review methods for tolerance induction and autoantibody suppression. Review of key articles published during the past half-century that have advanced knowledge in this field. Alloantibodies generally bind to the A2 or C2 domains of FVIII and disrupt the formation of the FVIII-FIX complex. They exhibit type 1 reaction kinetics, are saturable by FVIII, and display anamnesis. In contrast, autoantibodies usually bind to the C2 domain of FVIII, interfering with phospholipid and von Willebrand factor binding. They have type-2 kinetics and are poorly neutralized by FVIII. Repeated exposures to FVIII induce tolerance in 70-80% of haemophiliacs with inhibitors, whereas drugs that deplete B-lymphocytes restore self-tolerance to FVIII in a similar percentage of non-haemophiliacs. Future work should focus on improving assays that detect and quantify inhibitors, examining the pathophysiology of inhibitor formation using contemporary immunologic tools, and investigating new treatment modalities. These should include agents to control bleeding with less thrombotic risk, more specific immunomodulating drugs to curtail antibody formation, and, for haemophilia patients, genetic therapies to provide FVIII resistant to or protected from inactivation by inhibitors.

Acquired hemophilia a: diagnosis, aetiology, clinical spectrum and treatment options

Acquired hemophilia A (AHA) is a rare disorder with an incidence of approximately 1 per million/year with a high mortality rate of more than 20%. The disease occurs due to autoantibodies against coagulation factor VIII (FVIII) which neutralize its procoagulant function and result in severe, often life-threatening bleeding. The antibodies arise in individuals with no prior history of hemophilia A. AHA may be associated with pregnancy, autoimmune diseases, malignancy, infections or medication and occurs most commonly in the elderly. Approximately 50% of the patients remain idiopathic with no known underlying pathological condition. Clinical manifestations include spontaneous hemorrhages into the skin, muscles or soft tissues or excessive bleeding during surgery. Hemarthrosis which is the hallmark of congenital severe hemophilia A seldom occurs in AHA. The diagnosis of AHA is based on the isolated prolongation of activated partial thromboplastin time (APTT) which does not normalize after the addition of normal plasma along with reduced FVIII levels. The treatment involves two aspects-eradication of antibodies and maintaining effective hemostasis during a bleeding episode. The protocols for eradication of antibodies include immunoadsorption, immunosuppression or immune tolerance induction (ITI). The treatment of acute bleeding episodes involves use of different bypassing agents like recombinant activated factor VIIa (rFVIIa, NovoSeven®) and activated prothrombin complex concentrate (aPCC, (FEIBA®) in case of patients with high titer inhibitors or with antifibrinolytics,1-deamino-8-D-arginine vasopressin (DDAVP) or FVIII concentrates in low titer inhibitor patients. The anti CD20 monoclonal antibody, rituximab, has shown very good results either singly or in combination with immunosuppressive regimens in patients who do not respond to standard immunosuppressors. The present review summarizes the diagnostic, aetiological, clinical and treatment aspects of AHA focusing on the recent advances in this area.

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.

International recommendations on the diagnosis and treatment of patients with acquired hemophilia A

Acquired hemophilia A (AHA) is a rare bleeding disorder characterized by autoantibodies directed against circulating coagulation factor (F) VIII. Typically, patients with no prior history of a bleeding disorder present with spontaneous bleeding and an isolated prolonged aPTT. AHA may, however, present without any bleeding symptoms, therefore an isolated prolonged aPTT should always be investigated further irrespective of the clinical findings. Control of acute bleeding is the first priority, and we recommend first-line therapy with bypassing agents such as recombinant activated FVII or activated prothrombin complex concentrate. Once the diagnosis has been achieved, immediate autoantibody eradication to reduce subsequent bleeding risk should be performed. We recommend initial treatment with corticosteroids or combination therapy with corticosteroids and cyclophosphamide and suggest second-line therapy with rituximab if first-line therapy fails or is contraindicated. In contrast to congenital hemophilia, no comparative studies exist to support treatment recommendations for patients with AHA, therefore treatment guidance must rely on the expertise and clinical experience of specialists in the field. The aim of this document is to provide a set of international practice guidelines based on our collective clinical experience in treating patients with AHA and contribute to improved care for this patient group.

From theory to practice: applying current clinical knowledge and treatment strategies to the care of hemophilia a patients with inhibitors

Two bypassing agents are currently available to circumvent the need for factor FVIII in hemophilia A patients with inhibitors: the activated prothrombin complex FEIBA VH and recombinant activated factor VII (NovoSeven. Both products are highly effective in controlling bleeding in the presence of inhibitory alloantibodies, yet their hemostatic efficacy can be unpredictable. As the results of the FEIBA NovoSeven( Comparative (FENOC) study illustrate, patients may respond better to one bypassing agent than the other. Furthermore, guidelines from an expert panel reflect that responsiveness to bypassing therapy may change from one bleed to the next in the same patient and even from hour to hour during the course of a single bleeding event. These findings underscore the need to have both bypassing products available to treat bleeding episodes in inhibitor patients, to frequently evaluate the efficacy of hemostasis during the course of a bleeding event, and to switch products early if the response to treatment is unsatisfactory.

Complications of apheresis in children

BACKGROUND

Although the frequency of complications in adults undergoing therapeutic apheresis is low, there are little data in children.

STUDY DESIGN AND METHODS

A retrospective study of 186 children who had undergone a total of 1632 apheresis procedures between 1994 and 2002 was conducted. Adverse reactions were prospectively documented. The procedures were plasma exchange (67%), hematopoietic progenitor cell collection (18%), red blood cell exchange (6.9%), leukodepletion (0.7%), and plasma exchange with immunoadsorption (6.7%).

RESULTS

Adverse reactions, most minor, were reported in 55 percent of procedures in 82 percent of patients. The most frequent complications, per procedure and per patient during an entire course of therapy, were hypotension (14 and 48.4%), hypotension requiring fluid bolus (4.8 and 26.9%), symptomatic hypocalcemia (9.7 and 28.5%), allergic reactions (4.4 and 5.9%), catheter-related thrombosis (1.7 and 12.4%), catheter-related infection (2.1 and 16.1%), and severe anemia (hemoglobin [Hb] level, <7 g/dL; 2.5 and 17.2%). There were two deaths (1% of patients). Risk factors for complications by multivariate analysis were lower body weight, lower preapheresis Hb level, apheresis in a critical care unit, and number of procedures per patient. The 55 percent incidence of complications per procedure in our pediatric cohort is much higher than the 4.3 to 28 percent incidence reported in adults. The excess of adverse reactions in children are mostly related to citrate toxicity, higher relative vascular volume shifts, and the need for vascular access.

CONCLUSION

Pediatric apheresis presents unique challenges and is associated with higher complication rate compared to adults. It is recommended that this procedure be performed in specialized centers.

A systematic approach to controlling problem bleeds in patients with severe congenital haemophilia A and high-titre inhibitors

The presence of inhibitory antibodies to clotting factors complicates the treatment of bleeding in haemophilia patients. For patients with high-titre inhibitors, bypassing agents are essential to haemostatic management. To determine optimal treatment practices, an international panel of physicians convened to develop a systematic treatment approach for problem bleeds (i.e. bleeds that are unresponsive to initial therapy with a single agent within a reasonable amount of time) in haemophilia patients with inhibitors.

AIM

The goal of this panel was to develop a consensus algorithm that would aid physicians in considering a variety of treatment approaches to optimize patient care by preventing extensive therapy with inadequate treatments that may lead to suboptimal patient outcomes and unnecessary costs.

METHODS

Consensus opinions were analyzed for clinical preferences at different time periods, depending on patient response to treatment. Decision-making points were defined based on the type of bleed: every 8-12 h for the first 24 h, then every 24 h thereafter for limb-threatening bleeds; every 2-4 h for 2-7 days for life-threatening bleeds.

RESULTS

The resultant consensus guidelines provide a generalized methodology to guide the treatment of problem bleeds in patients with severe haemophilia A and inhibitors, and emphasize changing treatment at the first sign of an inadequate haemostatic response. The treatment algorithms apply to both paediatric and adult patients, although the differences between the two groups were reviewed.

CONCLUSION

These guidelines are focused on optimising the timing of treatment decisions, which may lead to faster responses and improved outcomes.

Coagulation factor concentrates: past, present, and future

Clotting factor transfusions are vital for people with diseases such as haemophilia. In the 1970s and 1980s, transfusions with pooled plasma led to a devastatingly high number of recipients becoming infected with blood-borne pathogens such as HIV and hepatitis C. This epidemic triggered the development of virus-free factor concentrates through a combination of improved donor selection and screening, effective virucidal technologies, and recombinant protein expression biotechnology. There is now a wide range of recombinant factor concentrates, and an impressive safety record with respect to pathogen transmission. However, remaining therapeutic challenges include the potential threat of transmission of prions and other pathogens, the formation of inhibitory alloantibodies, and the international disparity that exists in product availability due to differences in licensure status as well as prohibitively high costs. In the future, it is likely that bioengineered recombinant proteins that have been modified to enhance pharmacokinetic properties or reduce immunogenicity, or both, will be used increasingly in clinical practice.

International workshop on immune tolerance induction: consensus recommendations

Although immune tolerance induction (ITI) has been used for 30 years to eliminate inhibitors and restore normal factor pharmacokinetics in patients with hemophilia, there is a paucity of scientific evidence to guide therapeutic decision-making. In an effort to provide direction for physicians and hemophilia treatment center staff members, an international panel of hemophilia opinion leaders met to develop consensus recommendations for ITI in patients with severe and mild hemophilia A and hemophilia B. These recommendations draw on the available published literature and the collective clinical experience of the group and are rated based on the level of supporting evidence.

Immune tolerance therapy for factor VIII inhibitors: moving from empiricism to an evidence-based approach

Currently, the only proven strategy for achieving antigen-specific tolerance to factor VIII (FVIII) is immune tolerance induction (ITI) therapy. This paper discusses our current knowledge of the host and treatment factors, as well as supportive care initiatives, known or suspected to influence the outcome of ITI in the treatment of inhibitors arising in patients with severe hemophilia A. Among these, questions surrounding the choice of therapeutic product and/or dosing regimen generate the most controversy, given the lack of a definitive evidence-based approach to either. Furthermore, the potential for central venous access device (CVAD) and intercurrent bleeding complications to impact the ultimate success of ITI remains unclear. The ongoing clinical trials designed to further clarify several of these polarizing issues are reviewed. This paper also explores the current and future role of immune modulation in possible salvage, ancillary or primary alternative tolerance induction strategies. The special cases of low titer/ responding inhibitors and inhibitors developing in mild hemophilia A patients are considered. Finally, this paper summarizes the currently recommended approach to ITI and makes the case for a move from empiric therapeutics to a risk-stratified evidence-based approach to FVIII inhibitor eradication.

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.

Immunoadsorption with single-use columns for the management of bleeding in acquired hemophilia A: A series of nine cases

BACKGROUND

Acquired hemophilia A in a setting of bleeding or required surgery frequently places patients into a state of critical illness with high mortality. In this context immunoadsorption (IA) can be used to eliminate coagulation inhibitors quickly to employ recombinant coagulation factors more effectively. However, since acquired hemophilia is a rare condition the therapy is little standardized.

METHODS

We report on a retrospective analysis of nine cases of acquired hemophilia A treated with IA using disposable adsorber columns. Data collection was performed by retrospectively reviewing the patients' files regarding clinical course, mode of therapy, inhibitor titers, and coagulation status.

RESULTS

Inhibitor titers were effectively reduced in all but one patient following the treatment with IA. In two out of seven patients surviving the acute bleeding an inhibitor relapse occurred. The overall remission rate was determined as 77.8% within a median follow-up of 613 days. In two of our nine patients fatal outcome resulted due to major bleeding complications. IA treatment showed good tolerability and no fatal complications were caused.

CONCLUSION

The presented cases support our assumption that patients with acquired hemophilia A benefit from IA with disposable columns in a setting of acute bleeding. This modality of IA is able to eliminate inhibitors reliably and quickly. IA in general is substantially speeding up the progress of therapy preventing bleeding complications constantly threatening the patient and reducing the dosages of coagulation factor therapy. We encourage IA with disposable columns in all bleeding patients with acquired hemophilia to aggressively lower the inhibitors.

Application of current knowledge to the management of bleeding events during immune tolerance induction

The development of inhibitors to factor VIII is the most serious adverse event associated with the treatment of haemophilia A, predisposing patients to uncontrollable haemorrhage, disability and premature death. Eradication of inhibitors via immune tolerance induction (ITI) is effective in the majority of patients, but may require months to years to achieve success. In the interim, the treatment and prevention of acute bleeding episodes are primary foci of care. Regrettably, there is a paucity of information regarding management of bleeding episodes in inhibitor patients undergoing tolerization. Until specific data from ongoing clinical trials are available to provide more guidance in this patient group, it is reasonable and useful to rely on the broader base of medical literature pertaining to patients not being tolerized to deduce strategies for controlling acute and perioperative bleeding episodes in inhibitor patients during ITI.

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.

Italian guidelines for the diagnosis and treatment of patients with haemophilia and inhibitors

The Italian Association of Haemophilia Centres reviewed and finally approved in November 2004 the new Italian Guidelines for the diagnosis and treatment of patients with clotting factor inhibitors. The recommendations have been based on the identification of levels of clinical evidence derived from the systematic review carried out in 2003 by the School of Health and Related Research, the University of Sheffield, UK, and further integrated by clinical studies published from 2003 to 2004. The Italian guidelines consist of six major domains concerning inhibitor definition, epidemiology, risk factors, diagnosis, inhibitor eradication, management of bleeding episodes, in patients with congenital and acquired coagulation disorders, with 121 statements, 59 synthesis and 54 recommendations. We report here recommendations and open issues concerning the diagnosis and monitoring of inhibitors, inhibitor eradication and the management of bleeding in patients with haemophilia A and B.

Acquired Factor VIII Inhibitors: Pathophysiology and Treatment

Hemophilia A is classically caused by a congenital deficiency of factor VIII, but an acquired form due to inhibitors to factor VIII (FVIII) typically presents later in life. Patients who develop such acquired factor VIII inhibitors may present with catastrophic bleeding episodes, despite having no prior history of a bleeding disorder. Though the disorder is rare, it is known to cause significant morbidity and mortality. This review will focus on what is currently known about acquired hemophilia A, its pathogenesis, its associated etiologies, and its treatment.

Hemophilia management: optimizing treatment based on patient needs

PURPOSE OF REVIEW

Progress in hemophilia management over the past year has focused on improving understanding of the most common complications of genetic bleeding disorders and building upon available therapeutic strategies.

RECENT FINDINGS

Research continued to link factor VIII structure with immune recognition and inhibitor formation. Clinical regimens of immune tolerance induction confirmed and expanded basic understanding. Barriers to optimal prevention using prophylaxis were explored allowing future refinements to address unmet needs. Outcome tools to assess joint health and overall quality of life were developed and validated. The inclusion of standardized instruments in assessment of outcome will allow meaningful comparison of available therapies. Use and complications of central venous access devices (CVAD), needed to deliver aggressive infusion regimens, were exhaustively reviewed. Finally, continued progress was achieved in development of improved vectors for future gene therapy of the hemophilias.

SUMMARY

A general theme of recent progress in hemophilia management is harmonization in definitions and assessments of complications and outcomes, facilitating more rigorous and ultimately more useful interpretation of laboratory and clinical research.

Immunoadsorption of factor VIII inhibitors

PURPOSE OF REVIEW

Extracorporeal immunoadsorption is being increasingly applied in a variety of disorders. This approach is particularly suited to removal of antibodies or inhibitors to coagulation factor VIII and may be particularly useful before the administration of large amounts of expensive replacement or bypass therapy for patients with hemophilia who are bleeding, or patients undergoing immune tolerance therapy.

RECENT FINDINGS

In patients with inhibitors to factor VIII, several types of immunoadsorption therapy have been used, although reports are mainly anecdotal, consisting of relatively small numbers of persons. Nonetheless, the findings suggest that immunoadsorption may be clinically effective and cost-effective and should be considered early in the treatment of appropriate patients. New immunoadsorption technologies are being described for a variety of disorders, including hemophilia, and a new synthetic matrix of polystyrene beads functionalized with sulfonate and tyrosyl methylester groups for immunoadsorption removal of factor VIII inhibitors is intriguing.

SUMMARY

Although immunoadsorption was shown to be clinically effective in patients with inhibitors to factor VIII more than two decades ago, recent papers have emphasized the desirability of early implementation of the modality in the treatment plan. Immunoadsorption is relatively easy to perform with few adverse effects, but specialized equipment is required, and it should be performed in an experienced setting. Although potentially less costly than other (bypass) therapies, immunoadsorption is itself not inexpensive, and its comparative effectiveness with plasmapheresis and other management options for the dangerously bleeding patient with antibodies to factor VIII should be determined by multicenter randomized controlled trials. Interesting recent novel technical developments in the field may facilitate increased use of the procedure.