Successful treatment of high titer inhibitors in mild hemophilia A with avoidance of factor VIII and immunosuppressive therapy

Clinical Care of Bone Health in Patients on the Immune Tolerance Induction's Protocols With an Immunosuppressive Agent for Inhibitor Eradication in Hemophilia

Nowadays, the development of factor VIII and IX inhibitors in patients with hemophilia is considered as the most challenging in the treatment of hemophilia. Immune tolerance induction (ITI) therapy is an approach for eradication of inhibitors. Some ITI protocols are routinely in use for the eradication of inhibitors in patients with hemophilia. Moreover, such a therapeutic regimen may facilitate the tendency to reduced bone density in patients with inhibitor. This study scheduled to investigate whether that predisposing role of ITI protocols with an immunosuppressive agent has considered or not. By a literature review, published ITI protocols in hemophilia with inhibitors were evaluated. Among them, 51 papers found and studied thoroughly. None of them had performed the bone mineral examination in patients with hemophilia and inhibitor under treatment. Since there are 2 coexisting facilitating factors in these protocols, considering the bone mineral density study for patients with inhibitor who are undergoing ITI protocols with an immunosuppressive agent is recommended.

The incidence and treatment of bleeding episodes in non-severe haemophilia A patients with inhibitors

The development of an inhibitory antibody in non-severe haemophilia A patients may aggravate the bleeding phenotype considerably. Effective treatment of bleeding episodes may be challenging, with ensuing severe complications. At present, evidence is scarce for optimal treatment of bleeding episodes in this patient group. The aim of this study was to describe the incidence and the treatment of bleeding episodes in inhibitor patients in a population-based unselected cohort of non-severe haemophilia A patients with clinically relevant inhibitors. Data were available for 100 of the 107 non-severe haemophilia A patients (factor VIII (FVIII) baseline, 2–40 lU/dl) from 29 centres in Europe and one centre in Australia who had developed a clinically relevant inhibitor between 1980 and 2011. The majority (89 %) of the patients were treated during the inhibitor period for bleeding episodes or a surgical intervention: 66 % needed treatment for bleeding episodes, at a median annual bleeding rate (ABR) of 1.1 (interquartile range (IQR) 0.1–2.5) and a median total of 2 (IQR 1–6) bleeding episodes. Compared to the median ABR before inhibitor development of 0.095 bleeds per year (IQR 0.02–0.42), the increase in ABR is more than a 10-fold. More than 90 % of the bleeding episodes were treated with only one type of product, most frequently (51 %) FVIII concentrates. This study provides the incidence of bleeding episodes and treatment choices in non-severe haemophilia A patients with inhibitors. The 10-fold increase to a median ABR of 1.1 episodes per year emphasizes the impact of inhibitor development for non-severe haemophilia A patients.

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.

Rituximab as first-line treatment for the management of adult patients with non-severe hemophilia A and inhibitors

BACKGROUND

The role of immunosuppression in the management of patients with congenital hemophilia and inhibitors is uncertain. The use of rituximab has been limited to case reports and case series. In most reports, rituximab was used as second-line or third-line treatment following failure of conventional immune tolerance induction therapy, and more commonly in pediatric patients.

OBJECTIVES

The objective of this study was to describe our experience with rituximab for the eradication of factor VIII inhibitors in adult patients with non-severe hemophilia A.

PATIENTS

We retrospectively reviewed the medical records of adult patients with non-severe hemophilia A and a diagnosis of FVIII inhibitor treated with rituximab (four weekly doses of 375 mg m(-2) ) as first-line treatment at our hemophilia center.

RESULTS

We identified nine consecutive adult patients with hemophilia A (moderate, n = 5; mild, n = 4) at our institution between 2000 and 2013, with a median age of 54 years (range, 24-77 years) at the time of inhibitor diagnosis. No patient received concomitant immune tolerance induction therapy. All nine patients had successful eradication of FVIII inhibitors. The median time from the first dose of rituximab to a clinical response was 95 days (range, 12-278 days). The median follow-up was 56 months (range, 13-139 months). Following inhibitor eradication, eight patients were rechallenged with FVIII concentrates. Two patients developed inhibitor recurrence associated with surgery.

CONCLUSION

This case series demonstrates that rituximab is a useful first-line treatment to achieve sustained inhibitor eradication in adult patients with non-severe hemophilia A.

Factor VIII inhibitors in hemophilia A: rationale and latest evidence

Factor VIII (FVIII) replacement therapy is the foundation of treatment in hemophilia A and is effective unless a patient develops an alloantibody (inhibitor) against exogenous FVIII. Inhibitor development is currently the most significant treatment complication seen in patients with hemophilia and is associated with considerable morbidity and a decreased quality of life. The development of an inhibitor is the result of a complex interaction between a patient's immune system and genetic and environmental risk factors. The mainstay of treatment is the eradication of the inhibitor through immune tolerance. This review summarizes the current evidence regarding inhibitor risk factors, eradication, and hemostatic bypassing agents.

Eradication of factor VIII inhibitors in patients with mild and moderate hemophilia A

In hemophilia A, up to 25% of new antifactor VIII (FVIII) inhibitory antibodies (inhibitors) occur in patients with mild or moderate disease. Once the inhibitor develops, options for management include observation, immune modulation, and immune tolerance induction (ITI). Currently, there is little data to guide a clinician's management decisions. In a case series, eight of the 26 subjects with mild or moderate hemophilia complicated by an inhibitor underwent ITI; two were successful, two were unsuccessful, and four were partially successful. In a systematic review of the literature, 12 of the 16 patients with mild or moderate hemophilia responded to rituximab for treatment to eradicate the inhibitor. To increase our understanding of treatment options for inhibitor eradication in patients with mild or moderate hemophilia A complicated by an inhibitor, a secondary analysis of clinical and treatment characteristics in a cohort of 36 patients with mild or moderate hemophilia A and inhibitor was undertaken. In multivariate analyses, rituximab alone (n = 6) and other immune-modulating treatments alone (n = 2) were significantly associated with an increased likelihood of inhibitor clearance [hazard ratio (HR) = 4.4 (95% CI = 1.06–20.03) and 10.21 (95% CI = 1.17–78.28), respectively], whereas ITI alone (n = 9) was not [HR = 1.35 (95% CI = 0.44–4.07)].

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.

Mild haemophilia: a disease with many faces and many unexpected pitfalls

SUMMARY

Despite major advances in diagnosis and treatment, the management of patients with mild haemophilia (MH) remains a major challenge. Mild haemophilia is defined by factor levels between 0.05 and 0.40 IU mL(-1). The bleeding associated with mild haemophilia is most frequently episodic, occurring during surgery or following trauma. Spontaneous bleeding is rare. Diagnosis is sometimes delayed because of insensitivity of screening clotting assays or discrepancies in factor VIII activity as measured by different assays. The treatment of choice in mild haemophilia A is desmopressin, which typically induces a 2-6-fold increase of factor VIII over baseline. However, desmopressin has its limitations in this setting such as the occurrence of tachyphylaxis and failure to respond in an undetermined proportion of patients. Factors underlying poor biological response or magnitude of response to desmopressin are incompletely understood. Inhibitor development in mild haemophilia is particularly distressing. This complication arises at an older age in this patient group because of infrequent need for factor VIII replacement. Inhibitors in mild haemophilia patients often cross-react with endogenous factor VIII resulting in severe spontaneous bleeding frequently in a postoperative setting. Intensive perioperative use of factor VIII and some specific mutations induce a particularly high risk for inhibitor development, but risk factors are incompletely understood. For reasons of the older age of the patients, treatment of bleeding with bypassing agents may cause major thrombotic complications. Data on therapeutic options for inhibitor eradication in patients with mild haemophilia are particularly scarce. With increased life-expectancy for all haemophilia patients, the group of elderly patients with mild haemophilia requiring major surgery will further increase. Prevention of inhibitors, particularly in this patient group, should be a major topic of interest in both clinic and research.

Mild hemophilia A

Mild hemophilia A (HA), defined by clinical features and factor VIII coagulant activity (FVIII:C) between 0.05 and 0.40 IU mL(-1), is characteristically distinct from severe HA. Indeed, although the molecular characterization of mild HA has permitted the identification of specific underlying mutations, its clinical phenotype is strikingly different from that of patients with a severe FVIII defect, where spontaneous hemorrhages or recurrent joint bleeding are usual manifestations. With aging, mild HA patients may develop complications (i.e. cancers and cardiovascular disorders), the management of which may prove challenging due to the concomitant bleeding tendency. Furthermore, the development of inhibitors provides an additional major complication in these patients, because it increases the severity of the bleeding phenotype and complicates their management. Standard management of mild HA includes the use of desmopressin and antifibrinolytic agents for minor bleeding episodes or surgical procedures, whilst major bleeding or surgery requires replacement therapy with FVIII concentrates. As regards treatment of patients with inhibitors, bypassing agents (i.e. activated prothrombin complex concentrates and recombinant activated FVII) have proven effective in the treatment of bleeding episodes, but as there are insufficient data to determine the optimal approach to immune tolerance induction in this group of patients, their optimal management remains controversial. Rituximab is a newer, promising therapeutic option for inhibitor eradication in such patients. Many aspects concerning mild HA remain to be clarified, including the molecular basis, the natural history and the optimal diagnostic and therapeutic strategies. Only large prospective studies will shed light on this condition.

New Coagulant Agent (Ankaferd Blood Stopper) for Open Hemorrhages in Hemophilia With Inhibitor

The treatment of hemophilia A patients with inhibitor could be very expensive. Ankaferd blood stopper (ABS) is a unique folkloric medicinal plant extract, which has historically been used in Turkish traditional medicine as a hemostatic agent. In this article, a 16-year-old boy was presented with uncontrolled bleeding, despite the treatment of factor VIII, rVIIa, factor VIII inhibitor bypass activity (FEIBA), cyclophosphamide, and prednisolone at circumcision site that resolved with ABS in minutes. Our patient with hemophilia A and inhibitor is the first clinical pediatric case.

Intensive peri-operative use of factor VIII and the Arg593-->Cys mutation are risk factors for inhibitor development in mild/moderate hemophilia A

BACKGROUND

A severe and challenging complication in the treatment of hemophilia A is the development of inhibiting antibodies (inhibitors) directed towards factor VIII (FVIII). Inhibitors aggravate bleeding complications, disabilities and costs. The etiology of inhibitor development is incompletely understood.

OBJECTIVES

In a large cohort study in patients with mild/moderate hemophilia A we evaluated the role of genotype and intensive FVIII exposure in inhibitor development.

PATIENTS/METHODS

Longitudinal clinical data from 138 mild/moderate hemophilia A patients were retrospectively collected from 1 January 1980 to 1 January 2008 and analyzed by multivariate analysis using Poisson regression.

RESULTS

Genotyping demonstrated the Arg593Cys missense mutation in 52 (38%) patients; the remaining 86 patients had 26 other missense mutations. Sixty-three (46%) patients received intensive FVIII concentrate administration, 41 of them for surgery. Ten patients (7%) developed inhibitors, eight of them carrying the Arg593Cys mutation. Compared with the other patients, those with the Arg593Cys mutation had a 10-fold increased risk of developing inhibitors (RR 10; 95% CI, 0.9-119).The other two inhibitor patients had the newly detected mutations Pro1761Gln and Glu2228Asp. In both these patients and in five patients with genotype Arg593Cys, inhibitors developed after intensive peri-operative use of FVIII concentrate (RR 186; 95% CI, 25-1403). In five of the 10 inhibitor patients FVIII was administered by continuous infusion during surgery (RR 13; 95% CI, 1.9-86).

CONCLUSION

The Arg593Cys genotype and intensive peri-operative use of FVIII, especially when administered by continuous infusion, are associated with an increased risk for inhibitor development in mild/moderate hemophilia A.

Desmopressin for the treatment of haemophilia

The synthetic vasopressin analogue (1-deamino-8-D-arginine-vasopressin) increases plasma concentration of factor VIII and von Willebrand factor in normal subjects and patients with mild haemophilia A and von Willebrand disease. Since its first clinical use in 1977, desmopressin has become the treatment of choice for patients with haemophilia A and factor VIII coagulant activity (FVIII:C) > 5% and has spared several patients the risk of acquiring blood-borne viral infections due to the use of non-virally inactivated plasma-derived FVIII concentrates. An average two to sixfolds FVIII:C increase is typically observed in most patients and return to baseline occurs usually within 8 hours. Several clinical studies have demonstrated the clinical efficacy and safety of desmopressin and the availability of concentrated formulation for subcutaneous injection and of a nasal spray has paved the way to home-treatment. However, overall it appears that haemophilic children may have a lower rate of biologic response compared to adults and a minority of adult patients are not able to attain clinically useful FVIII:C levels post-desmopressin administration. Thus, in every patient with haemophilia A likely to be treated or candidate to an elective invasive procedure, a test-infusion/injection should be carried out to assess the future usefulness of the compound.

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.

Options for treating acute bleeds in addition to bypassing agents: extracorporeal immunoadsorption, FVIII/FIX, desmopressin and antifibrinolytics

Inhibitor patients do not always respond satisfactorily to treatment with bypassing agents, and options to the standard practice are sometimes needed. Temporary inhibitor removal may be achieved using extracorporeal immunoadsorption. This technique uses a column system including either protein A or antihuman IgG. Immunoadsorption may be used as part of an immune tolerance protocol, or in the case of acute bleeds or prior to surgery, thus rendering the patient more responsive to ordinary replacement therapy with factor VIII or factor IX. Desmopressin is a valuable haemostatic agent in many situations and can be especially recommended in mild haemophilia complicated by an inhibitor. Antifibrinolytics are often administered as an adjunct therapy to the treatment protocol and have also been reported to have a direct anti-inhibitor effect.

Continuous infusion of coagulation factors: current opinion

PURPOSE OF REVIEW

To review the most recent reports on continuous infusion of coagulation factors, focusing on the current issues relating to this mode of therapy.

RECENT FINDINGS

Continuous infusion has been extensively used as an alternative to intermittent bolus factor replacement since the 1990s. To date, more than 100 reports comprising more than 800 continuous infusion treatments in various clinical situations have been published, with an increase in the current utilization of recombinant coagulation factors. An excellent hemostatic efficacy of continuous infusion has been reported. Continuous infusion protocols, however, still vary widely in terms of the different hemostatic levels targeted, dosage regimens, modes of continuous infusion and duration of therapy, which obviously result in variations in the cost-effectiveness reported by different centers.

SUMMARY

Continuous infusion has been shown to be a safe and cost-effective mode of replacement for treatment of hemophilia. The lack of evidence-based information on the hemostatic levels to be maintained in specific clinical situations, and recent concerns regarding the development of inhibitors, particularly in patients with mild hemophilia treated with continuous infusion, need to be addressed by prospective, randomized studies that compare traditional intermittent injections and the continuous infusion mode of factor replacement.

Tyr2105Cys mutation in exon 22 of FVIII gene is a risk factor for the development of inhibitors in patients with mild/moderate haemophilia A

We report the case of a patient with mild haemophilia A, due to a Tyr2105Cys mutation in exon 22 of the C1 domain, who developed a high-titre factor VIII inhibitor (maximum titre 1600 BU) with recurrent severe haemorrhages and fatal intracranial bleeding. Based on published data, it appears that although this mutation occurs rarely in patients with mild or moderate haemophilia A, it is frequently associated with the development of high-titre inhibitors.

Impact of Choice of Treatment for Bleeding Episodes on Inhibitor Outcome in Patients With Mild/Moderate Hemophilia A and Inhibitors

Patients with mild/moderate hemophilia A (MHA) may develop inhibitors to factor VIII (FVIII). In this condition, FVIII clotting activity (FVIII:C) baseline levels may remain stable for some patients, but may be reduced to less than 0.01 U/mL for others. Several risk factors for the development of inhibitors in MHA have been proposed. Genetic factors, such as mutations in the FVIII gene, may play a central role; however, other influences, such as intensive treatment with FVIII products, may also be important. Optimal treatment regimens have yet to be determined, not only for the eradication of inhibitors, but also for the management or surgical prophylaxis of hemorrhages associated with this condition. Several treatment options for the control of bleeding in patients with MHA and inhibitors (MHAI) are currently available, and the choice of therapeutic strategy should be given careful consideration; some treatments may produce an anamnestic response, thus delaying the return to FVIII:C baseline levels and adversely affecting the duration of the severe bleeding phenotype. To increase our knowledge of MHAI, a retrospective collection of data is currently being performed among hemophilia centers in France and Belgium. Based on five examples of patients with MHAI collated from preliminary study data, we illustrate the impact on inhibitor outcome of the therapeutic choices used to treat bleeding episodes in these patients.

Rituximab for congenital haemophiliacs with inhibitors: a Canadian experience

When a high titre inhibitor develops in a patient with haemophilia, attempts are made to eradicate it through immune tolerance induction therapy (ITI) involving the frequent and regular administration of factor, usually for months to years. ITI is successful in only two thirds of patients prompting investigators to explore alternate regimens to use in haemophiliacs failing conventional ITI. Rituximab is an anti-CD20 monoclonal antibody, which has shown promise in the treatment of B-cell-mediated disorders. We developed a protocol for the use of rituximab in haemophilia A (HA) patients failing conventional ITI or in those haemophiliacs where the likelihood of success of conventional ITI is poor. Patients receive 375 mg m(-2) of intravenous rituximab weekly for 4 weeks followed by monthly (up to 5 months) until inhibitor disappearance and establishment of normal FVIII pharmacokinetics (recovery and half-life). Patients are concurrently placed on recombinant FVIII (100 U kg(-1) day(-1)). We have placed five haemophiliacs (four children with severe HA, and one adult with mild HA) on this protocol. In three patients (two with severe HA and one with mild HA) inhibitors disappeared although in neither severe haemophiliac did FVIII pharmacokinetics completely normalize. The fourth patient had a significant drop in inhibitor titres although not a complete disappearance of the inhibitor. All four of these patients ceased bleeding following rituximab. The fifth patient had no response to rituximab. This non-responding patient was not placed on concurrent FVIII. Our five cases suggest that rituximab may hold promise in the eradication of inhibitors. Prospective randomized studies are required to determine the value of this agent in inhibitor management.

Intensive exposure to factor VIII is a risk factor for inhibitor development in mild hemophilia A

BACKGROUND

Inhibitors are rare in boys with mild hemophilia A (MHA; factor (F)VIII:C > 5%) but may arise following intense FVIII exposure, e.g. continuous infusion (CI).

OBJECTIVES

To determine the impact of intense FVIII exposure in inhibitor formation in MHA at our institution and to compare this with previous reports.

PATIENTS AND METHODS

We reviewed FVIII exposure and inhibitor development in boys (ages 0-18 years) with MHA followed at our institution from 1996 to 2001 and conducted a Medline search (1966-2002) on the experience of inhibitor development following intensive/CI exposure to FVIII.

RESULTS

We identified 54 boys with MHA. Twenty-nine (54%) had been exposed to FVIII. Seven had received FVIII by CI. Four developed inhibitors; three high titer (at ages 10 years, 16 years and 17 years) and one low titer (at 1 month old). All four had received a CI of recombinant (r) FVIII of at least 6 days within 6 weeks of developing inhibitors. Baseline FVIII levels fell to < 1% in all cases and the three with high-titer inhibitors developed severe bleeding. Immune tolerance therapy (ITT) was attempted in two boys and was successful in one. Our literature search identified 35 cases (only four children) with MHA developing inhibitors following intense FVIII exposure often in the context of surgery.

CONCLUSIONS

The incidence of inhibitors in our MHA population was 7.4%. If expressed according to exposure the incidence was significantly higher: 14% (4/29) for any exposure to FVIII and 57% (4/7) for exposure by CI. A prospective study to address whether CI is associated with an increased incidence of inhibitor development in MHA is warranted.