Immune Tolerance Induction In Patients Research Articles

A review of immune tolerance induction with Haemate® P in haemophilia A

Immune tolerance induction (ITI) has been shown to successfully eliminate factor VIII (FVIII) inhibitors in haemophilia patients with inhibitors. We performed a literature search to identify reports from January 1980 to October 2012 on the use of the plasma-derived, von Willebrand factor (VWF)-containing FVIII concentrate Haemate P/Humate-P in the setting of ITI. Six reports were identified that specifically evaluated the use of Haemate P/Humate-P including 32 children and 9 adults. Dosing regimens ranged from 20 IU kg(-1) every 2-3 days in patients with low-responding (LR; n = 5) inhibitors to 300 IU kg(-1) day(-1) in patients with high-responding (HR; n = 36) inhibitors. Complete success was achieved in all five LR patients, in all three HR patients with good prognostic factors (age ≤7 years, pre-ITI inhibitor titre <10 BU, historical inhibitor titre <200 BU, time between inhibitor detection and ITI start <2 years), and in 24 of 33 (73%) HR patients with poor prognostic factors. The time to complete success was 0.5-4 months in good-prognosis patients and 0.5-42 months in poor-prognosis patients. Few adverse events were observed during ITI, and no cases of inhibitor relapse were reported with follow-up periods of up to 12 years. On the basis of this retrospective review of a diverse range of studies and case reports, we conclude that Haemate P/Humate-P for ITI in patients with inhibitors is effective and produces high rates of ITI success.

A3 Domain Region 1803–1818 Contributes to the Stability of Activated Factor VIII and Includes a Binding Site for Activated Factor IX

A recent chemical footprinting study in our laboratory suggested that region 1803-1818 might contribute to A2 domain retention in activated factor VIII (FVIIIa). This site has also been implicated to interact with activated factor IX (FIXa). Asn-1810 further comprises an N-linked glycan, which seems incompatible with a role of the amino acids 1803-1818 for FIXa or A2 domain binding. In the present study, FVIIIa stability and FIXa binding were evaluated in a FVIII-N1810C variant, and two FVIII variants in which residues 1803-1810 and 1811-1818 are replaced by the corresponding residues of factor V (FV). Enzyme kinetic studies showed that only FVIII/FV 1811-1818 has a decreased apparent binding affinity for FIXa. Flow cytometry analysis indicated that fluorescent FIXa exhibits impaired complex formation with only FVIII/FV 1811-1818 on lipospheres. Site-directed mutagenesis revealed that Phe-1816 contributes to the interaction with FIXa. To evaluate FVIIIa stability, the FVIII/FV chimeras were activated by thrombin, and the decline in cofactor function was followed over time. FVIII/FV 1803-1810 and FVIII/FV 1811-1818 but not FVIII-N1810C showed a decreased FVIIIa half-life. However, when the FVIII variants were activated in presence of FIXa, only FVIII/FV 1811-1818 demonstrated an enhanced decline in cofactor function. Surface plasmon resonance analysis revealed that the FVIII variants K1813A/K1818A, E1811A, and F1816A exhibit enhanced dissociation after activation. The results together demonstrate that the glycan at 1810 is not involved in FVIII cofactor function, and that Phe-1816 of region 1811-1818 contributes to FIXa binding. Both regions 1803-1810 and 1811-1818 contribute to FVIIIa stability.

Rituximab for the treatment of high titre inhibitors in mild haemophilia A.

Rituximab for the treatment of high titre inhibitors in mild haemophilia A.

Use of Haemate® P as immune tolerance induction in patients with severe haemophilia A who failed previous induction attempts: a multicentre observational study

Immune tolerance induction (ITI) can eliminate factor VIII (FVIII) inhibitory antibodies that appear during FVIII replacement therapy. If first-line ITI fails, switching to a different FVIII concentrate, especially one containing von Willebrand factor (VWF), has been advocated. The objective of the study was to assess the efficacy and safety of Haemate(®) P, a plasma-derived FVIII concentrate containing high levels of VWF, as ITI in severe haemophilia A patients who had failed at least one prior ITI attempt with a different FVIII concentrate. In this multicentre, observational study, Haemate(®) P was administered at a starting dose of 83-308 IU kg(-1) day(-1) (1500-6000 IU day(-1)). Efficacy was assessed by standard criteria (e.g. Bethesda titre, FVIII recovery and half-life), and bleeding characteristics. Nine patients from six haemophilia centres were treated with Haemate(®) P after failing one (n = 2), two (n = 5) or three (n = 2) prior ITI courses. The median time from inhibitor detection to Haemate(®) P treatment was 5.4 years. The median Haemate(®) P dose was 134 IU kg(-1), and the median treatment duration 32 months. During median of 47 months of follow-up, complete response, partial response and treatment failure were observed in one, three and five patients respectively. Five patients experienced seven adverse events (AEs), including two serious AEs (sepsis). Haemate(®) P was discontinued due to an AE in one patient with a partial response. Haemate(®) P salvage ITI resulted in complete or partial tolerization in four of nine patients (44%) who had failed previous ITI attempts using different FVIII concentrates.

Immune tolerance induction in patients with severe hemophilia with inhibitors: expert panel views and recommendations for clinical practice

For hemophilia patients with inhibitors, immune tolerance induction (ITI) may help to restore clinical response to factor (F) VIII or FIX concentrates. Several ITI regimens and protocols exist; however, despite 30 yr of progressive investigation, the ITI evidence base relies mainly on observational data. Expert opinion, experience, and interpretation of the available evidence are therefore valuable to support clinical decision-making. At the Sixth Zürich Haemophilia Forum, an expert panel considered recent data and consensus to distill key practice points relating to ITI. The panel supported current recommendations that, where feasible, ITI should be offered early to children and adults (ideally ≤ 5 yr of inhibitor detection) when inhibitor titers are <10 Bethesda units (BU) and should be stopped when successful tolerance is achieved. For hemophilia A inhibitor patients, ITI can be founded on recombinant FVIII at high doses. The panel considered that patients with a high bleeding frequency should be offered additional prophylaxis with a bypassing agent. For patients with hemophilia B, there may be a benefit of genetic testing to indicate the risk for inhibitors. ITI is often less effective and associated with a greater risk of side effects in these patients. For high-titer inhibitor (≥ 5 BU) hemophilia B patients, the panel advised that bypassing agents could be offered on demand in addition to ITI. Within future ITI regimens, there may be a role for additional immunosuppressant therapies. Participants agreed that research is needed to find alternatives to ITI therapy that offer durable and sustained effects and reduced rates of complications.

Mass Spectrometry-assisted Study Reveals That Lysine Residues 1967 and 1968 Have Opposite Contribution to Stability of Activated Factor VIII

The A2 domain rapidly dissociates from activated factor VIII (FVIIIa) resulting in a dampening of the activity of the activated factor X-generating complex. The amino acid residues that affect A2 domain dissociation are therefore critical for FVIII cofactor function. We have now employed chemical footprinting in conjunction with mass spectrometry to identify lysine residues that contribute to the stability of activated FVIII. We hypothesized that lysine residues, which are buried in FVIII and surface-exposed in dissociated activated FVIII (dis-FVIIIa), may contribute to interdomain interactions. Mass spectrometry analysis revealed that residues Lys(1967) and Lys(1968) of region Thr(1964)-Tyr(1971) are buried in FVIII and exposed to the surface in dis-FVIIIa. This result, combined with the observation that the FVIII variant K1967I is associated with hemophilia A, suggests that these residues contribute to the stability of activated FVIII. Kinetic analysis revealed that the FVIII variants K1967A and K1967I exhibit an almost normal cofactor activity. However, these variants also showed an increased loss in cofactor activity over time compared with that of FVIII WT. Remarkably, the cofactor activity of a K1968A variant was enhanced and sustained for a prolonged time relative to that of FVIII WT. Surface plasmon resonance analysis demonstrated that A2 domain dissociation from activated FVIII was reduced for K1968A and enhanced for K1967A. In conclusion, mass spectrometry analysis combined with site-directed mutagenesis studies revealed that the lysine couple Lys(1967)-Lys(1968) within region Thr(1964)-Tyr(1971) has an opposite contribution to the stability of FVIIIa.

A role for von Willebrand factor in immune tolerance induction in patients with haemophilia A and inhibitors?

In the era of safe factor VIII (FVIII) concentrates for replacement therapy and of the diffusion of primary prophylaxis to prevent arthropathy, the development of antibodies against therapeutically administered FVIII (inhibitors) remains the most serious complication of treatment of haemophilia A1. Circulating inhibitors, occurring in approximately 30% of severe (FVIII:C <1%) previously untreated patients (PUPs), result in partial or complete lack of efficacy of replacement therapy and hamper prophylaxis implementation in children1–2. Inhibitor patients are therefore exposed to higher morbidity, in terms of severity of bleeding and of their long-term sequelae of joint deterioration, and to a worse quality of life, mainly related to the poor orthopaedic status1,3–6. Thus, restoring the safe and effective standard FVIII treatment is crucial after inhibitor diagnosis and especially in children7–8. Immune tolerance induction (ITI) by means of regular and prolonged administration of FVIII concentrates is currently the only strategy proven to achieve such an objective, providing the complete inhibitor eradication (success) or avoiding high anamnestic response and enabling clinical response to FVIII infusions (partial success) in the majority of cases8. In spite of intensive clinical and molecular research, mechanisms affecting inhibitor generation and, on the other hand, the modulation and the eradication of such an adverse immune response, are still poorly elucidated9–10. A series of genetic, non-modifiable, as well environmental, thus potentially modifiable, conditions, have been identified as predictors of inhibitor development and/or response to ITI. The greatest interest is presently devoted to some treatment-related factors, which are more clearly affected by clinical choices, both at first replacement infusions in PUPs or when ITI is started in inhibitor patients, such as FVIII dose, regimen and type of concentrate1,8–9,11. In particular, the hypothesis of the different immunogenicity and/or antigenicity of recombinant and plasma-derived, von Willebrand Factor (VWF) containing, FVIII concentrates, affecting the rate of inhibitor development and of ITI success, is being keenly debated12–13. Clarifying this issue deserves important pathophysiological, clinical and, not least, economic implications. In the following paragraphs clinical and experimental data concerning the potential role of VWF in this setting, with emphasis on ITI, will be discussed.

Immune tolerance induction in patients with hemophilia A

Replacement therapy with factor VIII (FVIII) concentrates has become the mainstay of treatment for hemophilia, but about 30% of patients with a severe disease develop neutralizing antibodies against FVIII, which can lead to treatment resistance and an increased risk of bleeding. Immune tolerance induction (ITI) overcomes the immune response to FVIII concentrates in the majority of patients. Several factors may influence the efficacy of ITI, including disease-related factors (e.g. peak inhibitor titer and pre-ITI titer), and genetic factors (e.g. type of mutation). Treatment-related factors, such as the type of FVIII concentrate used in ITI will also potentially influence the outcome. Specifically, higher success rates with von Willebrand factor (VWF)-containing factor VIII concentrates than with high-purity FVIII concentrates have been reported, but further studies are needed. Potential mechanisms involved include steric hindrance, inhibition of FVIII degradation, or immunomodulatory effects. However, the exact mechanism by which immune tolerance is induced remains unclear. High-dose FVIII ITI appears to induce immune tolerance more rapidly than low-dose protocols and with a reduced risk of bleeding episodes. The addition of immunosuppressive therapy, such as rituximab, to ITI may improve outcomes, although the optimal approach to combined ITI/immunosuppression has not been established. Ongoing studies are likely to provide further insight into the role of genetic features and the type of FVIII concentrate on the success rate of ITI.

Domain specificity of factor VIII inhibitors during immune tolerance induction in patients with haemophilia A

Frequent administration of high dosages factor VIII (FVIII), so-called immune tolerance induction (ITI), provides an efficient strategy to eradicate inhibitory antibodies in patients with haemophilia A. At present, our knowledge on the characteristics of inhibitory antibodies in patients undergoing ITI is limited. In this study we characterized the domain specificity of FVIII inhibitors in 11 haemophilia A patients during ITI. In three of six patients who were successfully tolerized, inhibitory antibodies were directed predominantly against the FVIII light chain. In two other patients within this group, a significant contribution of A2 antibodies was observed which did not change during treatment. In the sixth patient the relative contribution of A2 inhibitors declined which coincided with an increase in antilight chain antibodies. In four of five patients who failed ITI, A2 inhibitors were observed. In two patients the contribution of A2 inhibitors increased during treatment, while in two other patients the contribution of A2 inhibitor remained constant. The fifth patient had inhibitory antibodies predominantly directed against the FVIII light chain. Overall, our findings revealed changes in domain specificity of FVIII antibodies in five of 11 patients analysed. Remarkably, antibodies exclusively directed towards the light chain of FVIII were predominantly observed in patients who were successfully tolerized.

Optimizing management of immune tolerance induction in patients with severe haemophilia A and inhibitors: towards evidence‐based approaches

Immune tolerance induction (ITI) is the only strategy proven to eradicate persistent inhibitors in severe haemophilia A patients. Thirty years experience has shown high success rates (60-80%) with heterogeneous dose regimens and has led to the identification of clinical features that define the patients' prognostic profile. Children with recently diagnosed inhibitors are the best candidates for ITI and adequate management may further contribute to improve the short- and long-term ITI outcome. In these patients inhibitor eradication represents a cost-effective option because it enables the restoration of FVIII prophylaxis and consequently prevents arthropathy development. Adults with long-standing inhibitors often show bad predictors of ITI outcome, however, ITI may be considered as a suitable and cost-effective approach in cases with frequent bleeds that are not satisfactorily controlled by by-passing treatment and/or when orthopaedic surgery is needed. Optimal ITI regimens should be established in these different settings and randomized trials are addressing these issues. This article reviews the available literature evidence and clinical implications with current recommendations on ITI management, and highlights the issues still unsolved.

Factor VIII gene (F8) mutations as predictors of outcome in immune tolerance induction of hemophilia A patients with high-responding inhibitors.

Immune tolerance induction (ITI) is the only therapeutic approach that can eradicate factor VIII (FVIII) inhibitors in patients with hemophilia A. Predictors of ITI outcome are still debated, and the role of F8 gene mutations in this is not well established. To investigate the relationship between F8 genotype and ITI outcome in patients with severe hemophilia A and high-responding inhibitors. F8 mutations were identified in 86 patients recruited as part of the Italian ITI registry (the PROFIT study). ITI outcome was centrally reviewed according to the following definitions: success (undetectable inhibitor and normal FVIII pharmacokinetics), partial success (inhibitor titer < 5 BU mL(-1) and/or abnormal FVIII pharmacokinetics), and failure. F8 mutations known to be associated with a high risk of inhibitor development (large deletions, inversions, nonsense mutations and splice site mutations) were found in 70 patients (81%); among these, the intron 22 inversion was present in 49 patients (57%). In 16 patients (19%) lower-risk F8 defects (small insertions/deletions and missense mutations) were identified. The latter group of patients showed a significantly higher ITI success rate than those carrying high-risk mutations [13/16 (81%) vs. 33/70 (47%); risk ratio 1.7, 95% confidence interval (CI) 1.1-2.1, P = 0.01]. On multivariate analysis, the mutation risk class remained a significant predictor of success [adjusted odds ratio (OR) 6.2, 95% CI 1.1-36.0, P = 0.04], as were inhibitor titer at ITI start (< 5 BU mL(-1), OR 11.8, 95% CI 3.5-40.2, P < 0.001), and peak titer during ITI (< 100 BU mL(-1), OR 11.4, 95% CI 3.2-40.8, P < 0.001). ITI success is influenced by F8 genotype. This knowledge should contribute to the stratification of prognosis, and to the clinical choices made for ITI in patients with high-responding inhibitors.

Experience with a third generation recombinant factor VIII concentrate (Advate®) for immune tolerance induction in patients with haemophilia A

The development of an inhibitor represents one of the most challenging complications in patients with haemophilia A. Optimal management is immune tolerance induction (ITI), typically through the administration of high doses of factor VIII (FVIII) concentrate. Among 12 patients who underwent ITI using Advate, a third-generation recombinant FVIII product that is free of animal and human protein additives, tolerance was achieved in nine (75%), including seven of 10 patients (70%) with high-titre inhibitors. ITI is ongoing in two patients and not yet successful; immune tolerance failed in the third patient. The median time to success was 4.0 months for group as a whole and for patients with high-titre inhibitors. Treatment was well tolerated, and no adverse events were observed. Advate was found to be equivalent to other FVIII products with regard to both ITI success rates and the incidence of adverse effects when used in these immune tolerance regimens.

Haemophilia care then, now and in the future

Epidemiological data show the benefits of dramatically improved haemophilia care in all life-stages. There are improved administration techniques and dosing regimens, a shift from on-demand treatment to prophylaxis, successful treatment protocols for immune tolerance induction in patients with inhibitors and enhanced approaches to overall patient management. Improvements also include the introduction of virus inactivation methods for plasma derived clotting factor concentrates and the development of recombinant factor VIII therapy, which practically eliminated the risk of infectious disease transmission. Recombinant factor concentrates are recommended as treatment of choice by several guidelines today. All these developments have resulted in increased health-related quality of life and life expectancy in haemophilia patients, who are transitioning from childhood to adulthood with healthy joints and an overall healthy status today. Because of increased life expectancy, these patients are expected to experience age-related clinical problems that were not previously observed in this population. With respect to this, the spectrum of haemophilia care will be extended to diseases of older ages with the need of including further disciplines in comprehensive haemophilia care programmes. Despite these advances, the short half-life of factor VIII, requiring re-administration every 2 or 3 days and the development of inhibitors remains a challenge. Bayer's research and development currently focuses on the optimization of recombinant coagulation factors to address these challenges. Haemophilia care has experienced significant improvements within the past decades. Novel technologies and continued clinical research have facilitated the development of treatment regimen that resulted in dramatic increases in the life expectancy and quality of life of haemophilia patients. To set the scene for the following papers dealing with haemophilia care from paediatrics to geriatrics, developments behind these improvements and some aspects of future research will be presented in this paper.

IgG subclasses of anti‐FVIII antibodies during immune tolerance induction in patients with hemophilia A

The eradication of inhibitory antibodies in patients with haemophilia A can be accomplished by frequent administration of high or intermediate doses of factor VIII (FVIII), so-called immune tolerance induction (ITI). This study monitored the distribution of IgG subclasses of anti-FVIII antibodies during ITI. FVIII-specific antibodies of subclass IgG1 were detected in all inhibitor patients tested, anti-FVIII IgG4 in 16, IgG2 in 10 and IgG3 in one of 20 patients analysed. Levels of anti-FVIII IgG1 and IgG4 correlated well with inhibitor titres as measured by Bethesda assay. In low-titre inhibitor patients, anti-FVIII antibodies consisted primarily of subclass IgG1 whereas, anti-FVIII antibodies of subclass IgG4 were more prominent in patients with high titre inhibitors who needed prolonged treatment or who failed ITI. Longitudinal analysis of 14 patients undergoing ITI revealed that the relative contribution of IgG subclasses was constant for most of the patients analysed. In two patients, the relative contribution of IgG4 increased during ITI. Overall, our findings document the distribution and dynamics of anti-FVIII IgG subclasses during ITI. Future studies will need to address whether monitoring the relative contribution of anti-FVIII subclasses IgG1 and IgG4 may be useful for the identification of patients who are at risk of failing ITI.

Immune tolerance induction in patients with IgA anaphylactoid reactions following long-term intravenous IgG treatment

To date, there is very little information regarding the pathomechanism of IgA anaphylactoid reactions and the management of affected patients. Five adult patients with common variable immunodeficiency (CVID) and a history of anaphylactic reactions due to the administration of immunoglobulin preparations were studied. The activity of anti-IgA was determined by the gel agglutination technique using IgA-coated beads. Antibodies to IgA were detected in the serum of all five patients. Initially, IgA 'depleted' intravenous (i.v.) IgG preparations were infused carefully into the patients until the activity of anti-IgA was decreased significantly or became undetectable. Subsequently, unselected i.v. IgG preparations were infused, and the activity of anti-IgA was abolished in all cases. Intravenous IgG long-term administration results in tolerance induction in patients with IgA anaphylactoid reactions. This tolerance appears to be related to antibody blockage in the circulation and an inhibition of antibody production. Most importantly, IgA appears to play an important role in the treatment of CVID. Patients with IgA anaphylactoid reactions can be treated safely with IgA containing i.v. IgG preparations following tolerance induction.

International workshop on immune tolerance induction: consensus recommendations1

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.

Reduction of Anti-FIX Inhibitor Titers in a Hemophilia B Patient with Continuous Use of FEIBA.

Background: Inhibitor formation is a severe complication of hemophilia B associated with poor response to factor replacement and uncontrolled bleeding, although an inhibitor formation in hemophilia B is a rare event compared to hemophilia A. Currently, immune tolerance is the only proven method for inhibitor eradication. However, immune tolerance induction in patients with hemophilia B is a rare occurrence. We report a case of a hemophilia B patient who had a reduction of inhibitor titer during continual use of FEIBA.Case report: Patient is an 11-year-old boy with severe FIX deficiency and high titer inhibitor (historical peak: 65 BU/mL) since age 3 years. Since inhibitor formation, the patient had received FEIBA or FVIIa on demand. FVIIa became therapeutically not effective in 1999 October, and bleeding frequency increased as he developed a target joint. In 1999 November, 2002 February, and 2004 September, he received high dose of FIX concentrate for neutralization of inhibitor and then cyclophosphamide for 8 weeks. We achieved only a transient effect in reducing the inhibitor titer. The inhibiter titer fluctuated between 20 and 60 BU/mL. Since 2005 January, subsequently, he had received FEIBA 1,000–2,000 IU per dose (30–50 units/kg) on demand. He needed FEIBA twice or thrice a week, and continued to receive this dose till now. The inhibitor titer was gradually getting lower after a transient rise up to 39 BU/mL on 2005 February. On 2006 February, the inhibitor titer became below 1.0 BU/mL, and finally undetectable on 2006 March, despite the longevity of the inhibitor (8 years). Factor IX recovery was normalized, and bleeding frequency dramatically decreased. Elimination of the inhibitor by the continued administration of FEIBA was observed. Anaphylactic reaction and the development of nephrotic syndrome were not seen.Conclusion: The continuing use of FEIBA safely and effectively might decrease the inhibitor titer and the frequency of bleeding episodes in hemophilia B patients. This case may provide us the optimization of the FEIBA dose, and duration of treatment for inducing tolerance by using FEIBA.

Immune tolerance induction in patients with haemophilia A with inhibitors: a systematic review.

In some patients with haemophilia A, therapeutically administered factor VIII (FVIII) comes to stimulate the production of antibodies (inhibitors) which react with FVIII to render it ineffective. As a result, FVIII cannot be used prophylactically and patients become liable to recurrent bleeds. There are two elements to the management of patients with inhibitors: the treatment of bleeding episodes, and attempts to abolish inhibitor production through the induction of immune tolerance. This paper reports a systematic review of the best available evidence of clinical effectiveness in relation to immune tolerance induction (ITI) in patients with haemophilia A with inhibitors. Owing to the lack of randomized controlled trials on this topic, broad inclusion criteria with regard to study design were applied in order to assess the best available evidence for each intervention. As a result of the clinical and methodological heterogeneity of the evidence, it was not appropriate to pool data across studies; instead, data were synthesized using tabulation and qualitative narrative assessment. The International Registry provides the most reliable estimate of the proportion of successful cases of ITI [48.7%, 95% confidence interval (CI) 42.6-52.7%]. The duration of effect is unclear, but relapses appear to be infrequent. The International Registry shows a rate of relapse of 15% at 15 years. The comparative effectiveness of different protocols is uncertain, as no trials have been undertaken which compare them directly. However, the evidence suggests that the Bonn protocol may be more effective than the Malmö or low-dose protocols. There is no good evidence that immunosuppressive drug regimens are effective.