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Background Immune tolerance induction (ITI) is the treatment of choice for eradication of anti-factor VIII (FVIII) neutralizing alloantibodies (inhibitors) in people with inherited hemophilia A and high-responding inhibitor (PwHA-HRi). The association between ITI outcome and time elapsed between inhibitor detection and start of ITI ( increment t(inhi-ITI)) is debatable. Objective The aim of this study was to evaluate this association among a large cohort of severe PwHA-HRi. Methods Severe (factor VIII activity level 0.6-1.7 year), third (>1.7-9.2 years), and fourth quartile (>9.2-24.5 years). The overall success rate was 65.5% (93/142), with no difference among first, second, third, and fourth quartiles (62.9%, 69.4%, 58.3%, and 71.4%, respectively) even after adjusting the analyses for potential confounders. Conclusion In conclusion, delayed ITI start is not associated with failure of ITI in PwHA-HRi. Therefore, ITI should be offered for these patients, regardless of the time elapsed between the detection of inhibitor and the ITI start.

Introduction: The development of inhibitory antibodies (inhibitors) in persons with hemophilia B (PwHB) causes significant morbidity. Data on the impact of the F9 variant and immune tolerance induction (ITI) outcome are limited.The aim of this study was to investigate the presence of neutralizing and non-neutralizing antibodies (NNA) in severe hemophilia B (HB) and to evaluate ITI outcome and complications in relation to the pathogenic F9 variant.Materials and methods: Persons with severe HB in the Nordic countries were enrolled and information on F9 variants, inhibitors, ITI and complications were collected. Analyses of anti-FIX antibodies with a fluorescence -immunoassay (xFLI) and an ELISA method were conducted.Results: Seventy-nine PwHB were enrolled. Null variants were seen in 33 (42 %) PwHB and 12 (15 %) had a current or former inhibitor. Eleven (92 %) of the inhibitor patients had experienced allergic manifestations and three (25 %) nephrotic syndrome. Of 10 PwHB with at least one ITI attempt, eight (80 %) were considered tolerant at enrolment. Immunosuppression was included in seven of eight successful or partially successful at-tempts. Five PwHB had at least one ITI failure before a successful or partially successful ITI. No NNA could be identified.Conclusion: A high proportion of severe F9 gene defects among persons with severe HB in the Nordic countries may explain the observed relatively high prevalence of inhibitors. ITI success was independent of the F9 variant and attained despite allergic manifestations and previous ITI failures. Inclusion of immunosuppression tenta-tively enhances the chances of ITI success. No NNA were observed.

Background Classic infantile onset of Pompe disease (c-IOPD) leads to hypotonia and hypertrophic cardiomyopathy within the first days to weeks of life and, without treatment, patients die of cardiorespiratory failure in their first 1–2 years of life. Enzymatic replacement therapy (ERT) with alglucosidase alfa is the only available treatment, but adverse immune reactions can reduce ERT’s effectiveness and safety. It is therefore very important to identify strategies to prevent and manage these complications. Several articles have been written on this disease over the last 10 years, but no univocal indications have been established. Methods Our study presents a review of the current literature on management of immune responses to ERT in c-IOPD as considered by an Italian study group of pediatric metabolists and immunologists in light of our shared patient experience. Results We summarize the protocols for the management of adverse reactions to ERT, analyzing their advantages and disadvantages, and provide expert recommendations for their optimal management, to the best of current knowledge. However, further studies are needed to improve actual management protocols, which still have several limitations.

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Replacement therapy with coagulation factor VIII (FVIII) represents the current clinical treatment for patients affected by hemophilia A (HA). This treatment while effective is, however, hampered by the formation of antibodies which inhibit the activity of infused FVIII in up to 30% of treated patients. Immune tolerance induction (ITI) protocols, which envisage frequent infusions of high doses of FVIII to confront this side effect, dramatically increase the already high costs associated to a patient's therapy and are not always effective in all treated patients. Therefore, there are clear unmet needs that must be addressed in order to improve the outcome of these treatments for HA patients. Taking advantage of preclinical mouse models of hemophilia, several strategies have been proposed in recent years to prevent inhibitor formation and eradicate the pre-existing immunity to FVIII inhibitor positive patients. Herein, we will review some of the most promising strategies developed to avoid and eradicate inhibitors, including the use of immunomodulatory drugs or molecules, oral or transplacental delivery as well as cell and gene therapy approaches. The goal is to improve and potentiate the current ITI protocols and eventually make them obsolete.

AimFor previously untreated patients (PUPs) with severe haemophilia A in Finland for the past 2 decades, the standard practice has been to start early primary prophylaxis. We evaluated the long-term clinical outcomes and costs of treatment with high-dose prophylaxis in PUPs from birth to adolescence, including immune tolerance induction (ITI). MethodsFrom the medical records of all PUPs born between June 1994 and May 2013 in Finland, we retrospectively extracted data on clinical outcomes and healthcare use. Using linear mixed models, we analysed longitudinal clinical outcome data. To analyse skewed cost data, including zero costs, we applied hurdle regression. ResultsAll 62 patients received early regular prophylaxis; totally, they have had treatment for nearly 700 patient-years. The median age of starting home treatment was 1.1years. The mean (SD) annual treatment costs (Europerkg) were 4391Euro (3852). For ages 1-3, ITI comprised over half of the costs; in other groups, prophylactic FVIII treatment dominated. With these high costs, however, clinical outcomes were desirable; median (IQR) ABR was low at 0.19 (0.07-0.46) and so was AJBR at 0.06 (0-0.24). Thirteen (21%) patients developed a clinically significant inhibitor, 10 (16%) with a high titre. All ITIs were successful. The mean costs for ITI were 383448Euro (259085). The expected ITI payback period was 1.81 (95% CI 0.62-12.12) years. ConclusionsEarly high-dose prophylaxis leads to excellent long-term clinical outcomes, and early childhood ITI therapy seems to turn cost-neutral generally already in 2years.

Background: Inhibitor development is the most serious treatment-related complication of replacement coagulation factor VIII (FVIII) therapy for patients with haemophilia A. Immune tolerance induction (ITI), which involves intensive and prolonged treatment with plasma-derived or recombinant FVIII, is the only clinically proven strategy for eradication of inhibitors. The bispecific antibody emicizumab is approved for use in patients with and without inhibitors to prevent bleeding but does not eliminate inhibitors. MOTIVATE ( www.motivate-study.com ) aims to capture different approaches to the treatment and management of patients with haemophilia A and inhibitors, document current ITI approaches from real-world clinical experience, and evaluate the efficacy and safety of ITI, emicizumab prophylaxis and ITI with emicizumab prophylaxis. Methods: The investigator-initiated MOTIVATE study [ClinicalTrials.gov identifier: NCT04023019; EudraCT 2019-003427-38] will investigate in real-life clinical practice the management of patients with haemophilia A of any severity who have developed inhibitors to FVIII. All treatment is at the investigator’s discretion. The following treatment approaches will be evaluated: Group 1 – ITI with Nuwiq®, octanate® or wilate® and aPCC/rFVIIa if needed to treat bleeding episodes (BEs) or during surgery or for prophylaxis; Group 2 – ITI with Nuwiq®, octanate® or wilate® and emicizumab prophylaxis and aPCC/rFVIIa if needed to treat BEs or during surgery; Group 3 – routine prophylaxis with emicizumab, aPCC or rFVIIa without ITI and aPCC/rFVIIa if needed to treat BEs or during surgery. Patients will not be randomised to a treatment group and may change groups during the study. Conclusions: It is planned to enrol 120 patients who will be followed for up to 5 years. Optional sub-studies will explore factors that may influence ITI results as well as the impact of different treatment approaches on important aspects of patient health, including joint and bone health and the risk of thrombotic events.

Introduction As a result of the new treatment paradigm that the haemophilia community will face with the availability of novel (non-factor) therapies, an updated consensus on ITI recommendations and inhibitor management strategies is needed. Aim The Future of Immunotolerance Treatment (FIT) group was established to contemplate, determine and recommend the best management options for patients with haemophilia A and inhibitors. Discussion and Conclusions Despite the considerable success of emicizumab in the management of inhibitor patients, the FIT group still sees the importance of eradicating inhibitors. However, the availability of emicizumab and other non-factor therapies in the future might impact greatly on how ITI is undertaken. Theoretically, concomitant use of emicizumab and FVIII might allow emicizumab to effectively prevent bleeding with lower dose ITI regimens. This might allow for the greater adoption of low-dose/low-frequency FVIII ITI regimens, which may result in a reduced need for central venous access devices while still maintaining a reasonable likelihood of ITI success. The FIT group proposes a new management algorithm for current ITI (without emicizumab) and a hypothetical new approach with the availability of emicizumab. As there are no published data regarding the concomitant use of emicizumab and FVIII for ITI, the FIT Expert group encourages the undertaking of properly conducted prospective studies to explore these approaches further.

Background: The appearance of inhibitors is the most serious complication in haemophilia A (HA) patients. The primary objective is their eradication. Up to date, immune tolerance induction (ITI) was the only therapeutic option to achieve this. Aim: To assess the efficacy of moroctocog-alpha as an ITI regimen in a population of HA patients with high-titre inhibitors. Methods: The REF.IT Registry is a retrospective-prospective study that collected data on all patients with HA and high-titre inhibitors treated with moroctocog-alpha as an ITI regimen at twelve Italian Haemophilia Centres. Results: We enrolled 27 patients, 85.2% were children. All patients were high responders, 88.9% had severe HA. We found 69.3% of them had one or more risk factors for poor ITI prognosis, 14.8% were ITI rescue. Overall 59.3% achieved a complete/partial success (complete in 51.9%). ITI failed in 11 patients, 63.6% of them with poor-prognosis risk factors. Inhibitors appeared after a mean of 27 exposure days. Mean historical peak was 78.8BU/mL. The primary ITIs started on average 20.2months after the diagnosis. A partial or complete success after a mean of 15months of treatment was achieved in 56.6% of the children while the same result was obtained by 75.0% adults after 22months from ITI onset. Patients who were treated with high-dose moroctocog-alpha (200UI/kg/day) were 63.0%. Conclusion: Our Registry showed that the use of moroctocog-alpha in the setting of ITI was effective and safe also in a population of patients with high-titre inhibitors, presenting one or more risk factors for poor ITI prognosis.

Introduction As a result of the new treatment paradigm that the haemophilia community will face with the availability of novel (non‐factor) therapies, an updated consensus on ITI recommendations and inhibitor management strategies is needed. Aim The Future of Immunotolerance Treatment (FIT) group was established to contemplate, determine and recommend the best management options for patients with haemophilia A and inhibitors. Discussion and Conclusions Despite the considerable success of emicizumab in the management of inhibitor patients, the FIT group still sees the importance of eradicating inhibitors. However, the availability of emicizumab and other non‐factor therapies in the future might impact greatly on how ITI is undertaken. Theoretically, concomitant use of emicizumab and FVIII might allow emicizumab to effectively prevent bleeding with lower dose ITI regimens. This might allow for the greater adoption of low‐dose/low‐frequency FVIII ITI regimens, which may result in a reduced need for central venous access devices while still maintaining a reasonable likelihood of ITI success. The FIT group proposes a new management algorithm for current ITI (without emicizumab) and a hypothetical new approach with the availability of emicizumab. As there are no published data regarding the concomitant use of emicizumab and FVIII for ITI, the FIT Expert group encourages the undertaking of properly conducted prospective studies to explore these approaches further.

The development of alloantibodies against the replacement of Factor VIII (FVIII) is the major complication in haemophilia A treatment. The gold standard to eradicate inhibitors is the immune tolerance induction (ITI), but in some cases it fails requiring another immune tolerance, defined ITI rescue (ITI-R), using a different concentrate, even though it is still debated. We report a successful case of a poor risk (titre of inhibitor at start of ITI > 10 BU/ml, peak titre on ITI > 200 BU/ml, >2 years since the inhibitor diagnosis) haemophilia A child treated with a high-dose regimen (200 UI/kg/day) turoctocog-alfa after a failed first-line ITI with octocog-alfa lasting 29 months. At 22 months of ITI-R, the inhibitor titre was undetectable, the FVIII recovery was 74%, of the expected level and the FVIII half-life more than 7 h. A complete successful ITI-R was then achieved with turoctocog-alfa.

Enzyme replacement therapy (ERT) has led to a significant improvement in the clinical course of patients with infantile Pompe disease (IPD), an autosomal recessive glycogen storage disorder characterized by the deficiency in lysosomal acid α-glucosidase. A subset of IPD patients mounts a substantial immune response to ERT developing high sustained anti-rhGAA IgG antibody titers (HSAT) leading to the ineffectiveness of this treatment. HSAT have been challenging to treat, although preemptive approaches have shown success in high-risk patients (those who are cross-reactive immunological material [CRIM]-negative). More recently, the addition of bortezomib, a proteasome inhibitor known to target plasma cells, to immunotherapy with rituximab, methotrexate, and intravenous immunoglobulin has shown success at significantly reducing the anti-rhGAA antibody titers in three patients with HSAT. In this report, we present the successful use of a bortezomib-based approach in a CRIM-positive IPD patient with HSAT and the use of a preemptive approach to prevent immunologic response in an affected younger sibling. We highlight the significant difference in clinical course between the two patients, particularly that a pre-emptive approach was simple and effective in preventing the development of high antibody titers in the younger sibling, thus supporting the role of immune tolerance induction (ITI) in the ERT-naïve high-risk setting.

目的 探讨血友病B伴抑制物的免疫耐受诱导（ITI）治疗，提高血友病B伴抑制物的诊疗水平。 方法 应用基于APTT标准曲线的一期法测定重型血友病B患者凝血因子Ⅸ（FⅨ）活性，应用Bethesda法进行FⅨ抑制物定量测定；利用凝血酶原复合物（PCC）进行ITI并联合利妥昔单抗清除患者抑制物。 结果 患儿既往PCC暴露日为20 d，抑制物滴度峰值为56 BU/ml。在2015年11月患儿抑制物滴度降至10.4 BU/ml时开始ITI治疗，单用PCC一段时间无效，给予PCC联合利妥昔单抗治疗，17个月后成功清除患者体内FⅨ抑制物，未发生过敏反应及肾病综合征等并发症。ITI过程中患者年化出血率有所改善。 结论 该患者是国内首例报道的采用ITI联合利妥昔单抗成功治疗血友病B伴抑制物的病例。PCC联合利妥昔单抗ITI治疗是目前有希望清除血友病B抑制物的方法。

In children with severe haemophilia A, inhibitors to factor VIII (FVIII) usually develop during the first 50 treatment exposure days and are classified as low or high titre depending on the peak inhibitor titre being greater or less than 5 Bethesda units/mL (BU/mL). Classification of the inhibitor may change with time, as some low-titre inhibitors progress to high titre following re-exposure to FVIII concentrate. The aim of this study was to investigate potential risk factors for such a progression in children with severe haemophilia A and newly diagnosed inhibitors. This study was a follow-up study of the PedNet Registry and included 260 children with severe haemophilia A and inhibitors born between 1990 and 2009 and recruited consecutively from 31 haemophilia centres. Clinical and laboratory data were collected from the date of each child's first positive inhibitor test for at least 3 years. At the time of first positive inhibitor test, 49% (n = 127) had low-titre inhibitors, with 50% of them progressing to high titre and only 25% maintaining low titres. The FVIII gene (F8) mutation type was known in 247 patients (95%), and included 202 (82%) null mutations. The progression to high-titre inhibitors was associated with null F8 mutations (odds ratio [OR]: 2.6; 95% confidence interval [CI]: 1.0-6.5), family history of inhibitors (OR: 7.2; 95% CI: 1.8-28.4) and the use of high-dose immune tolerance induction, defined as >= 100 IU FVIII concentrate/kg/d (OR: 3.9; 95% CI: 1.5-10.0). These results suggest that high-dose immune tolerance induction should be avoided as the initial strategy in patients who develop low-titre FVIII inhibitors.

ObjectiveA number of hemophilia A patients who receive clotting factors may develop antibodies (inhibitors) against clotting factors. The immune tolerance induction (ITI) method has proved to be a very cost-effective alternative to bypassing agents. Iran's national health authority is interested in implementing the ITI method for the management of hemophilia patients with inhibitors. The objective of this study was to calculate the breakeven point between costs attributed to the ITI method and the use of bypassing agents for the management of high-responder hemophilia patients with inhibitors.MethodsThis study assessed costs attributed to the implementation of ITI for the management of Iranian hemophilia patients with costs of high-titer and high-responding inhibitors from the perspective of the national health system. The main objective was to find the breakeven point for the ITI method in comparison with the use of bypassing medicine, recombinant factor VIIa (Novoseven).ResultsBased on the sensitivity analysis performed, the breakeven point mainly depends on costs of factor VIII, Novoseven, and the success rate of the ITI intervention. According to this analysis, the breakeven point of ITI and Novoseven methods varies between 16 and 34 months posttreatment. The optimized point is about 17 months posttreatment.ConclusionsIran's national health system spends more than 24 million euros for providing bypassing agents to about 124 hemophilia patients with inhibitors. Because of limited resources available in Iran's health sector, this is a huge burden. Results of this study show that the implementation of the ITI method for the management of Iranian hemophilia patients with inhibitors is a cost-saving method and Iran's health system will recover all the expenditure related to the implementation of ITI in less than 2 years and will make a considerable saving along with providing standard care for these patients.

Summary. Background: Replacement therapy in severe hemophilia A patients is complicated by formation of inhibitory antibodies against factor VIII (inhibitors) in around 25% of children. Management of bleeds and eradicating inhibitors is complicated, costly and not always successful. Objective: To develop a simple score that stratifies untreated patients with severe hemophilia according to their risk of developing inhibitory antibodies. Methods: The study population consisted of 332 children, with severe hemophilia A, selected from a retrospective multicentre cohort (the CANAL study). The score was based on risk factors available at the first treatment episode. The score was validated in an external population. Results: A total of 87 patients (25%) developed inhibitory antibodies. The selected risk score comprised positive family history (two points), high risk factor VIII gene mutations (two points), and intensive treatment at initial treatment (three points). Inhibitor incidence was 6% (six of 95) in patients without risk factor, 23% (38 of 170) in those with two points, and 57% (38 of 67) in patients with three points or more. The discriminative ability of the score was good (area under the receiver operating curve 0.74). The score performed equally well in the external validation population. Conclusion: These findings suggest that the development of inhibitory antibodies in untreated patients with severe hemophilia A can validly be predicted with the presented risk stratification score.

Background Inhibitory antibodies to factor VIII (FVIII) are an important complication when managing patients with hemophilia A. Immune tolerance induction (ITI) has been regarded as a useful method for eradicating inhibitors. We report the results of a retrospective study in Korean patients with hemophilia A who underwent ITI. Methods We reviewed the records of patients with hemophilia A with inhibitors who underwent ITI from March 2004 to December 2014. ITI was started with FVIII concentrates at 100 IU/kg, 3 times per week. The dose of FVIII was reduced according to the inhibitor titer and recovery of FVIII. 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. Results In total, 17 patients with severe hemophilia A were evaluated. Complete tolerance was achieved in 14 of 17 patients (83%). The mean peak inhibitor titer before ITI was 38.4 BU/mL. The mean treatment duration was 26.2 months. The mean duration between inhibitor detection and ITI was 5.1 years in the complete tolerance group and 10.8 years in the partial tolerance and failed group. Conclusion This study shows that ITI can be an effective and well-tolerated method for eradicating inhibitors. Possible influencing factors for ITI success were age at the start of ITI treatment and duration after inhibitor detection. More research to provide further insight about other factors and conditions is needed.

Hamid Reza Rasekh1, Ali Imani1, Mehran Karimi2, Mina Golestani11Shahid Beheshti University of Medical Sciences, Department of Pharmaceutical Management and Pharmacoeconomics, School of Pharmacy, Tehran, 2University of Shiraz Medical Sciences, Hematology Research Center, Shiraz, IranBackground: In developing countries, the treatment of hemophilia patients with inhibitors is presently the most challenging and serious issue in hemophilia management, direct costs of clotting factor concentrates accounting for >98% of the highest economic burden absorbed for the health care of patients in this setting. In the setting of chronic diseases, cost-utility analysis, which takes into account the beneficial effects of a given treatment/health care intervention in terms of health-related quality of life, is likely to be the most appropriate approach.Objective: The aim of this study was to assess the incremental cost-effectiveness ratios of immune tolerance induction (ITI) therapy with plasma-derived factor VIII concentrates versus on-demand treatment with recombinant-activated FVIIa (rFVIIa) in hemophilia A with high titer inhibitors from an Iranian Ministry of Health perspective.Methods: This study was based on the study of Knight et al, which evaluated the cost-effectiveness ratios of different treatments for hemophilia A with high-responding inhibitors. To adapt Knight et al's results to the Iranian context, a few clinical parameters were varied, and cost data were replaced with the corresponding Iranian estimates of resource use. The time horizon of the analysis was 10 years. One-way sensitivity analyses were performed, varying the cost of the clotting factor, the drug dose, and the administration frequency, to test the robustness of the analysis.Results: Comparison of the incremental cost-effectiveness ratios between the three ITI protocols and the on-demand regimen with rFVIIa shows that all three ITI protocols dominate the on-demand regimen with rFVIIa. Between the ITI protocols the low-dose ITI protocol dominates both the Bonn ITI protocol and the Malmö ITI protocol and would be the preferred ITI protocol. All of the three ITI protocols dominate the on-demand strategy, as they have both a lower average lifetime cost and higher quality-adjusted life-years (QALYs) gained. The cost per QALY gained for the Bonn ITI protocol compared with the Malmö ITI protocol was $249,391.84. The cost per QALY gained for the Bonn ITI protocol compared with the low-dose ITI protocol was $842,307.69.Conclusion: The results of data derived from our study suggest that the low-dose ITI protocol may be a less expensive and/or more cost-effective option compared with on-demand first-line treatment with rFVIIa.Keywords: cost-utility analysis, immune tolerance induction, on-demand, rFVIIa