Immune tolerance induction with a high purity von Willebrand factor/VIII complex concentrate in haemophilia A patients with inhibitors at high risk of a poor response

Immune tolerance induction (ITI) is effective in approximately 70% of haemophilia patients with inhibitors. Poor prognostic factors are age >6 years, ITI started >1 year from inhibitor development, inhibitor peaks >200 BU, inhibitor titre >10 BU when ITI is started and previously failed ITI. The objective of this study was to identify the effectiveness in ITI of a high purity von Willebrand factor/factor VIII (VWF/FVIII) complex concentrate in inhibitor patients at high risk of failure. Patients with severe or moderate haemophilia A and high responding inhibitors who had at least one poor prognostic factor for ITI failure were prospectively followed-up. Success was defined by undetectable inhibitor, recovery and half life >66% of expected values. ITI dose regimens were chosen by each haemophilia centre. Seventeen haemophiliacs (16 severe, one moderate), aged 4-54 years (median 23) were followed-up for 6-71 months. Poor prognostic factors were delayed-onset ITI (n = 16), age >6 years (n = 16), previously failed ITI (n = 4), inhibitor peak >200 BU (n = 2) and inhibitor >10 BU when ITI was started (n = 4). Complete success was obtained in nine patients (53%) after 4-30 months of treatment (median 24), including two of four patients who had previously failed ITI. Seven patients achieved a partial success, with sustained low inhibitor titres (median 1.5 BU, range 1.1-2.8) but abnormal recovery and/or half-life, while the remaining patient withdrew ITI after 12 months when the inhibitor titer was still 70 BU. These findings suggest that high purity VWF/FVIII complex concentrates are effective in ITI, even in patients at high risk of failure.     

Immune tolerance induction in the treatment of paediatric haemophilia A patients with factor VIII inhibitors

The development of an inhibitor to transfused factor VIII (FVIII) is a serious treatment-related problem in haemophiliac children. The management of patients with high titre FVIII inhibitors is difficult, and immune tolerance induction (ITI) is the only method available for the eradication of these inhibitors. The results of the ITI regimen used at the Children's Hospital of Michigan Haemophilia Treatment Center are described and discussed. ITI was attempted in 14 children with severe haemophilia A (13 high responders, one low responder), with daily doses of FVIII alone. FVIII dosage was chosen according to the patient's historical peak inhibitor titre. ITI included three phases; induction phase, dose reduction phase and maintenance phase. During the first phase, the starting dose was 50 or 100 U kg-1 d-1; during the second phase the FVIII dosage was reduced gradually to 25 U kg-1 every other day according to the inhibitor titre, FVIII recovery and/or half-life study. In the third (maintenance) phase, the children received either prophylactic therapy or episodic therapy for 12 months. The inhibitor elimination was defined as the time taken to achieve a negative inhibitor assay with no anamnestic response and normal FVIII recovery and/or normal half-life. Immune tolerance was achieved in 11 of 14 patients (79%) patients within a median time of 6 months; two children are still on therapy, three failed ITI. We observed either failure or prolongation of immune tolerance if the historical peak titre or the maximum titre during ITI was >200 BU. The success rate of our low dose ITI regimen is not different from that reported by other investigators and the inhibitor elimination time is similar to some of the studies reported previously.     

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.     

Immune tolerance induction with recombinant factor VIII in hemophilia A patients with high responding inhibitors

Immune tolerance induction (ITI) eradicates inhibitors in patients with hemophilia A. This study was designed to investigate the success rate of ITI in high-responding inhibitor patients with severe hemophilia A using recombinant factor VIII (rFVIII). Twenty-six patients received different ITI regimens until a normal recovery (>66%) and half-life (>6 h) of infused FVIII was achieved. In order to maximize the chance of success, the initiation of ITI was deferred in the majority of patients until the inhibitor declined to <10 BU. Twenty-two patients (85%) had baseline inhibitor levels <10 BU (median 2.3 BU) when ITI began. Within a median of 6 months, immune tolerance was achieved in 19 of 26 patients (73%) including 12/17 (70%) with intron 22 inversion, 5/7 (71%) with other null mutations and two with small deletion/insertions in the F8 gene. In conclusion, recombinant FVIII induces a high rate of immune tolerance even in carriers of null F8 mutations.     

Successful induction of immune tolerance with FIX recombinant in a patient with haemophilia B with inhibitor

We describe successful induction of immune tolerance in a 12-month-old patient with severe haemophilia B and low-titre and low response antifactor IX inhibitor at 5 Bethesda Unit (BU). Immune tolerance induction (ITI) was started with recombinant factor (rFIX) at 40-50 U kg(-1) day(-1) (1000 U three times per week) and 2 years after the beginning of therapy the inhibitor had been reduced to undetectable values. As complications, which appeared during the ITI, the patient presented minor haemorrhagic complications, which remitted following the administration of rFVIIa, and recurring infections of the catheter, requiring the withdrawal and subsequent placement of a new catheter.     

Immune tolerance induction with mycophenolate-mofetil in two children with haemophilia B and inhibitor

Summary.  Immune tolerance induction (ITI) in haemophilia B patients with inhibitor should be carefully considered because of the relatively poor (25%) overall success rate and the high risk of complications. ITI in combination with an immunosuppressive treatment was started in two children with haemophilia B with factor IX (FIX) inhibitor. To avoid anaphylactic reactions and inhibitor boost, the FIX replacement therapy was stopped and patients received a treatment with recombinant activated factor VII (rFVIIa). After disappearance of FIX inhibitor, a combination of mycophenolate-mofetil (MMF), dexamethasone (DEXA) and intravenous immunoglobulin (IVIG) and a high dose FIX replacement therapy was started. Immune tolerance could be induced in patient 2, whereas eradication of FIX inhibitor was incomplete in patient 1. Both patients benefited from the immune suppressive treatment and FIX replacement therapy was tolerated without any allergic complications. Neither development of a nephrotic syndrome nor a severe bleeding episode was observed. Strategies to induce tolerance in haemophilia B patients with inhibitors need to be explored in a systematic way. Given the low frequency of disease and even lower incidence of inhibitors, prospective randomized studies may not be possible. International registry-based retrospective and prospective data collection could play the key role in the study of the outcome variables in ITI for haemophilia B.     

Immune tolerance induction in haemophilia A patients with high-responding inhibitors to factor VIII: experience at a single institution

Inhibitor antibodies to transfused factor VIII pose significant challenges in the management of haemophilia A patients. The main concern is the inefficacy of replacement therapy in patients with high-titre antibodies, who have a shorter life-span and a greater morbidity compared to subjects without inhibitors. The ultimate goal in treating these patients is to eliminate the inhibitor antibody entirely, allowing the recommencement of specific replacement therapy. The results of an immune tolerance regimen based on pharmacokinetic parameters are reported here. In 12 high-responder haemophilia A patients immune tolerance induction (ITI) was attempted with daily administration of factor VIII concentrates of very high purity, either plasma-derived or produced by recombinant-DNA technology. Patients were given 100 IU kg(-1) day(-1) until the inhibitor was shown to be absent by at least two negative assays 1 month apart, with normal recovery of infused factor VIII and normal half-life (> 6 h), as assessed after a 3-day washout period. After the patient was judged to be inhibitor-free, immune tolerance treatment was continued with unmodified factor VIII doses for 2 months. Doses were thereafter gradually reduced and finally, regular prophylaxis by administration of 25 IU kg(-1) three times weekly was instituted. Immune tolerance was achieved in 10 of the 12 patients (including six of seven with long-standing inhibitors) within a median time of 8 months. Outcome of immune tolerance was not influenced by age at start of ITI nor by the interval between inhibitor development and ITI. The success rate and the inhibitor disappearance time of our immune tolerance regimen, utilizing high-purity factor VIII, agrees with those reported by other investigators.     

Prophylaxis with FEIBA in paediatric patients with haemophilia A and inhibitors

The benefits shown with factor VIII (FVIII) prophylaxis relating to joint health and quality of life (QoL) provide the rationale for FEIBA prophylaxis in haemophilia A patients with persistent FVIII inhibitors. FEIBA has previously shown efficacy in preventing bleeds in inhibitor patients who failed to respond to, or were ineligible for immune tolerance induction (ITI). The study examined the outcome of paediatric patients undergoing long‐term FEIBA prophylaxis. A retrospective chart review included severe haemophilia A patients with persistent inhibitors aged ≤13 years at the start of FEIBA prophylaxis. Baseline characteristics captured dose, frequency of prophylaxis, history of inhibitor development, including baseline titre, historical peak titre and history of ITI. Outcome measurements included annual bleed rate before and during FEIBA prophylaxis, joint status and school days missed. Sixteen cases of FEIBA prophylaxis from two centres are presented. The mean age of subjects at prophylaxis initiation was 7.5 ± 3.6 years and median baseline inhibitor titre was 23 (range 3.1–170) BU. Prior to prophylaxis initiation, median annual joint bleeds among all patients was 4 (0–48), which dropped significantly after the first year of prophylaxis, to a median annual joint bleed rate of 1 (0–7; P = 0.0179). Subsequent years (median = 9) of prophylaxis therapy demonstrated similarly low annual joint bleed rates. There were no life‐threatening bleeds, no viral seroconversions or thrombotic events during FEIBA prophylaxis treatment. FEIBA prophylaxis was effective for preventing joint bleeds and subsequent joint damage, delaying arthropathy and improving outcomes in children with haemophilia A and inhibitors to FVIII, who failed or were ineligible for ITI.     

Immune tolerance induction in 31 children with haemophilia A: is ITI less successful in African Americans?

Summary. Inhibitor development continues to be a major problem in the treatment of haemophilia. Immune tolerance induction (ITI) continues to be the most effective approach to managing this complication. This study reviews the practice and outcome of ITI at a single centre over a 17‐year period. All 31 inhibitor patients have haemophilia A. Two patients with haemophilia A underwent two trials of ITI and a third patient underwent three trials of ITI for a total of 35 courses of ITI in these 31 patients. Most patients had high responding inhibitors, 22 of 31. Seventy‐one percent of haemophilia patients achieved tolerance. Courses of ITI in African American (AA) patients with haemophilia A were much less likely to achieve tolerance compared with non‐AAs, 57.9% and 92% (P = 0.04) respectively. Most trials of ITI were carried out with recombinant products (25 of 35). While ITI continues to be an effective therapy for patients with inhibitors, it is less effective in AA patients, and patients with higher inhibitor titres. In this refractory group of patients, new approaches are needed.     

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 therapy utilizing factor VIII/von Willebrand factor concentrate in haemophilia A patients with high titre factor VIII inhibitors

Summary.  Factor VIII (FVIII) inhibitors remain a serious complication of treatment for patients with haemophilia A. Immune tolerance induction (ITI) can eliminate inhibitors in the majority of patients, but there are major concerns related with this therapy. Investigators have raised the possibility that the use of FVIII/von Willebrand factor (FVIII/VWF) concentrates may improve the success rate of ITI and may shorten the duration of therapy necessary to attain tolerance. This retrospective study describes 25 patients at five institutions in the USA, who were treated with FVIII/VWF concentrate as part of their ITI. These were all patients who were considered poor prognosis because of clinical and laboratory characteristics, which made ITI less likely to be successful or because of a poor response to initial ITI with a monoclonal/recombinant FVIII concentrate. Overall success (complete tolerization) was 32% with another 40% attaining partial tolerization, but not complete tolerization. Of those patients attaining only partial tolerization, two patients ultimately discontinued ITI and had return of their high titre inhibitors. Eight percent of patients failed to attain either partial or complete tolerization and discontinued ITI. Another 24% are continuing with ITI but have titres of >10 BU. This study adds further retrospective data to the information regarding the use of FVIII/VWF concentrate in ITI.     

Primary and rescue immune tolerance induction in children and adults: a multicentre international study with a VWF‐containing plasma‐derived FVIII concentrate

Most studies on immune tolerance induction (ITI) therapy in haemophilia A patients are focused on primary ITI in children. Here we report on the ITI outcome in a large retrospective cohort, including adults and patients with rescue ITI, treated with a pdFVIII/VWF concentrate. Retrospective data from haemophilic patients (FVIII< 2%) with inhibitors from 22 centres in Spain, Italy and Germany, who underwent primary or rescue ITI with pdFVIII/VWF concentrate, were collected. Complete success (CS), partial success (PS) and failure were defined based on the criteria of the consensus recommendations of the 2006 International ITI Workshop. A total of 41 cases of primary ITI (32 children and 9 adults) and 19 cases of rescue ITI (17 children and 2 adults) were evaluated. Success (CS+PS) rate of 87% was achieved in primary ITI and 74% in the higher risk profile of rescue ITI. Eight of nine (85%) patients with poorest prognosis (three or more of the known risk factors of poor response to ITI) achieved success (CS+PS). CS of 100% was observed in eight primary ITI patients with titre at start of ITI ≤2.5 BU and inhibitor peak ≤25 BU. The favourable response rates in primary and rescue ITI in children and in adult patients, even in the presence of poor prognostic factors, should be encouraged for broadening the indication of immune tolerance therapy in haemophilia A patients with inhibitors.     

Low-dose immune tolerance induction in hemophilia A patients with inhibitors

In patients with hemophilia A and inhibitory alloantibodies against factor VIII, various dosage schedules are used to obtain immune tolerance. In this study, we have evaluated the results of 13 years of low-dose immune tolerance induction and factors that are predictive of a positive result. The effect of immune tolerance induction in relation to age at inhibitor development, number of exposure days, age at start of therapy, maximum inhibitor titer, factor VIII products involved, and virologic status were determined. We evaluated 24 patients with severe hemophilia A and inhibitors who were treated with regular infusions with low-dose (25 U/kg every other day) factor VIII to obtain immune tolerance. In 21 of 24 patients (87%), immune tolerance induction was successful. The response time was determined by two factors: the highest inhibitor level and the age at inhibitor development. In patients with maximum inhibitor levels of less than 40 Bethesda units (BU)/mL, immune tolerance was obtained sooner than in patients with inhibitor levels exceeding 40 BU/mL (P = .005). Patients in whom an inhibitor developed before the age of 2.5 years also tended to have a quick immune response (P = .014). Immune tolerance with low-dose factor VIII is often successful in hemophilia A patients with inhibitors. Young children and patients with maximum inhibitors of less than 40 BU/mL show a relatively rapid response.     

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

Summary.  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.     

Late immune tolerance induction in haemophilia A patients

The incidence of inhibitor development in patients with severe haemophilia A is approximately 30%. Immune tolerance induction (ITI) is commonly utilized to eradicate these antibodies and is successful in 63–100% of cases. Potential predictors of a poor outcome in ITI include a high preinduction titre, high historical peak titre, older age at start of ITI and prolonged interval from diagnosis to start of ITI. The goal of this study was to characterize the outcomes of patients from our centre who have undergone late ITI, many of whom had poor prognostic features. Medical records of patients in our centre with severe/moderately severe haemophilia A (< 2% FVIII activity) and history of inhibitor were reviewed. Data were abstracted from all patients who attempted late ITI. Nine patients underwent late ITI between January 1999 and December 2011. Within this cohort, 7 (78%) patients were black, 6 (67%) were <21 years old and 4 (44%) had a family history of inhibitor. Three patients had previously received ITI unsuccessfully. To date, 4 (44%) patients are tolerized (persistently negative inhibitor titre, FVIII recovery >66% and successfully treated with FVIII products ±FVIII t^½ of > 6 h). Three patients are partially tolerized (have low responding inhibitor, variable FVIII recovery and successfully treated with FVIII products). Two patients are not tolerized. Some patients with haemophilia A and long‐standing inhibitors may benefit from ITI.     

Concomitant infusion of low doses of rFVIIa and FEIBA in haemophilia patients with inhibitors

Summary.  Patients with severe haemophilia A and an inhibitor may become refractory to FEIBA and/or recombinant factor VIIa (rFVIIa). Sequential therapy with both products has been reported in such patients. In this pilot study, we examined the safety and efficacy of combined rFVIIa and FEIBA therapy in patients with haemophilia A and inhibitors during bleeding episodes. We also tried to evaluate whether thrombin generation (TG), by various mixtures of these agents, can serve as a guide for tailoring therapy. TG was measured in plasma taken from eight haemophilia A patients. Increasing concentrations of rFVIIa, FEIBA or both were added ex vivo to the plasmas, and TG was induced by recalcification. Since low concentrations of rFVIIa and FEIBA had either an additive or a synergistic effect in all patients, the lowest combination, yielding TG comparable or lower than TG achieved with either FEIBA 100 U kg⁻¹ or rFVIIa 160 μg kg⁻¹ alone, was selected for the treatment of bleeding episodes. Five patients with a high titre of an inhibitor (8–1300 BU), including one previously refractory to infusions of rFVIIa at doses up to 400 μg kg⁻¹ X4 daily, were treated with combinations of 30–70 μg kg⁻¹ rFVIIa and 20–30 U kg⁻¹ FEIBA during a total number of 400 bleeding episodes with excellent haemostatic effect. No adverse events and no DIC were observed following these infusions. Concomitant infusion of low-dose rFVIIa and low-dose FEIBA, seems to be safe, efficacious and economical in patients refractory to rFVIIa and probably other haemophilia A patients with an inhibitor.     

Frequency of inhibitor development in severe haemophilia A children treated with cryoprecipitate and low-dose immune tolerance induction.

The frequency of factor VIII inhibitor development was evaluated in a hundred severe haemophilia A patients < 18 years of age (mean 10.4 +/- 5.1 years); 25 were previously untreated patients (PUPs), with a mean age of 11.2 +/- 2.9 months. All were followed up for 3 years from December 1996. Immune tolerance (IT) was induced with low-dose factor VIII (FVIII); 25-50 IU kg(-1) every other day for the 10 haemophiliacs who developed persistent inhibitors. The incidence of inhibitors for PUPs was 3/25 (12%; 95% confidence interval [CI], 0. 7-24.7%) and were detected after 4, 15 and 20 exposure days (mean 13 +/- 8.2 days; 95% CI, 3.7-22.2%). Children with maximum inhibitor levels of > 40 Bethesda units (BU) per mL (n=4) received IT therapy as 25 U kg(-1) FVIII in the form of cryoprecipitate every other day for 1-4 months (mean 2.4 +/- 1.6 months; 95% CI, 0.8-3.9%), which was successful in all of them. FVIII (50 U kg(-1)) was given every other day for six patients with maximum inhibitor level > 40 BU mL(-1) for 3-9 months (mean 5.4 +/- 3.2 months; 95% CI, 2.9 -7.9%) with success in 4/6 (66.6%; 95% CI, 28.8-104.3%). Patients who showed a good IT response had an inhibitor level < or = 30 BU mL(-1), were < or = 9 years of age at inhibitor development with few exposure days to FVIII and had an early immune tolerance. In conclusion, inhibitor development in severe haemophilia A children exclusively treated with cryoprecipitate is low. Early low-dose IT induction for high responders may be achieved successfully if inhibitor level is < or = 50 BU mL(-1).     

Inhibitor development and substitution therapy in a developing country: Turkey

Prevalence of inhibitor in developing countries, such as Turkey, where fresh frozen plasma (FFP) is still in use due to high cost of concentrates, is unknown. To determine the frequency of inhibitors in Turkish Haemophiliacs exposed to blood products, 53 Haemophilia A patients (age range 1–20; median: 11 years) and 12 Haemophilia B patients (age range 3–20; median: 10 years), were evaluated; 31 Haemophilia A patients (23 severe) received plasma-derived concentrates and 22 patients (10 severe) only FFP. No Haemophilia B patients developed inhibitor, compared with seven of 53 (13%) Haemophilia A patients, all with a severe defect (7/33; 21%) and treated with concentrates (7/23; 30%), whereas severe patients treated with FFP showed a lower risk to develop inhibitors (0/10, P  = 0.07). Inhibitors were detected after 8–125 exposure days (median: 52). Intermediate-purity concentrates and pasteurization seemed to be linked with a higher risk of inhibitor compared to high-purity concentrates and solvent-detergent inactivation for seven patients with inhibitor. In four of seven inhibitor patients low-dose concentrate was administered at 25 IU kg⁻¹ twice weekly and inhibitor disappeared in 1–4 months. This regimen might be recommended for immune tolerance in developing countries for its lower cost.     

Economic modelling of different treatment strategies for haemophilia A with high-responding inhibitors

Summary. This paper reports a systematic review of the cost‐effectiveness of treatment options in patients with haemophilia A with inhibitors. As very little relevant published evidence was identified, an economic modelling exercise was undertaken to calculate the cost‐effectiveness of different strategies in the treatment of high‐responding haemophilia A patients with inhibitors. A decision analysis approach was used to model the expected lifetime clinical outcomes and costs of the more common regimens currently used in UK in treating severe haemophiliacs with inhibitors. The model attempts to reflect the outcomes of clinical events, costs and life expectancy for each different treatment regimen for haemophilic boys with inhibitors who are high responders (defined as inhibitor level ≥10 BU) throughout their life. The basic model structure is centred on a Markov decision process, which was used to simulate, at quarter‐yearly intervals, the movement through discrete health states and their complications. The model allows a comparison of cost‐effectiveness between three immune tolerance induction (ITI) regimens (Bonn, Mälmo and Low‐Dose protocols) and against a relevant ‘on‐demand’ (OD) regimen. It also shows the cost‐effectiveness of different OD regimens using different bypassing agents. The results of the economic modelling indicate that treating haemophilia A patients who have high‐responding inhibitors OD with recombinant activated factor VII is cost‐effective compared to treatment with activated prothrombin complex concentrates. However, when OD treatment regimens are compared with the three ITI protocols, the Malmö ITI protocol is the preferred treatment strategy, generating more quality adjusted life‐years (QALYs) and less cost than either an OD regimen or the Bonn or Low‐Dose ITI protocols.