Serious Complication Of Haemophilia Research Articles

Single-facility study of the effectiveness of rehabilitation therapy using wearable hybrid assistive limb for patients with bleeding disorders: study protocol for a randomised controlled trial

IntroductionHaemophilic arthropathy, a serious complication of haemophilia, results from recurrent joint bleeding, causing progressive joint damage and severely impacting patient quality of life. Rehabilitation therapy (RT) effectively addresses declining physical...

Hemophilia a patients with inhibitors: Mechanistic insights and novel therapeutic implications.

The development of coagulation factor VIII (FVIII) inhibitory antibodies is a serious complication in hemophilia A (HA) patients after FVIII replacement therapy. Inhibitors render regular prophylaxis ineffective and increase the risk of morbidity and mortality. Immune tolerance induction (ITI) regimens have become the only clinically proven therapy for eradicating these inhibitors. However, this is a lengthy and costly strategy. For HA patients with high titer inhibitors, bypassing or new hemostatic agents must be used in clinical prophylaxis due to the ineffective ITI regimens. Since multiple genetic and environmental factors are involved in the pathogenesis of inhibitor generation, understanding the mechanisms by which inhibitors develop could help identify critical targets that can be exploited to prevent or eradicate inhibitors. In this review, we provide a comprehensive overview of the recent advances related to mechanistic insights into anti-FVIII antibody development and discuss novel therapeutic approaches for HA patients with inhibitors.

Risk of Intracranial Hemorrhage in US Patients with Hemophilia a: Real-World Retrospective Cohort Study Using the Athndataset

Background Intracranial hemorrhage (ICH), a serious complication of hemophilia A (HA), causes high rates of mortality and morbidity (Zanon. Blood Transfus. 2019). The risk of developing ICH is 10 to 20 times higher in patients with HA (PWHA) than in individuals without (Zanon. 2019). Patient data from 1998 through 2008 identified several risk factors for ICH, including presence of an inhibitor and prior ICH (Witmer. Br J Haematol. 2010). However, standard of care and the treatment landscape have evolved (Srivastava. Haemophilia. 2020). This study leverages clinical information from the ATHNdataset to assess the incidence of ICH in non-neonate (≥2 years of age) PWHA and determine the association between ICH risk and key characteristics. Methods This retrospective cohort study used data from PWHA (male, aged >2 and <75 years) who had visit information from January 1, 2010, through September 30, 2020, as identified in the ATHNdataset. The American Thrombosis & Hemostasis Network (ATHN) is the steward of the ATHNdataset, a Health Insurance Portability and Accountability Act-compliant, de-identified patient health dataset containing data from individuals with bleeding disorders receiving care through ATHN affiliates who opt in to contribute. The unadjusted incidence rate (IR) and incidence rate ratio (IRR) were evaluated by inhibitor and prophylaxis status. Association between patient characteristics and risk of ICH (HR) was evaluated by time-to-event analysis using univariate and multivariate Cox proportional-hazards (CoxPH) models. Stratified bootstrap analysis and penalty-based ridge regression sensitivity analyses were done to account for the rarity of ICH and small sample bias. Results In over 10 years and 9 months of collected data, 135 of 7837 PWHA (1.7%) had an ICH, with a median follow-up time of 10.7 patient-years. The incidence of ICH by demographic, clinical, and treatment characteristics is described in Table 1. In the unadjusted analysis, stratification by inhibitor status had an IRR (IR+/IR-) of 1.76 (95% CI: 0.97-3.20; P=0.059). IRR (IR+/IR-) by prophylaxis status in the unadjusted analysis was 0.63 (95% CI: 0.43-0.94; P=0.02). Univariate CoxPH modeling and multivariate CoxPH modeling with interaction, with associated bootstrap and ridge regression analyses, identified factors associated with differential risk of developing ICH (Table 2). Characteristics associated with a greater risk of developing ICH include being between the ages of 2 and 12 years, having ever been on Medicaid, having had HIV, hepatitis C (HCV), or hypertension (HTN) comorbidities, and never having received factor VIII (FVIII) or prophylactic treatment. In the multivariate population analysis, the estimated HR for patients never receiving prophylaxis was 7.67 (95% CI: 0.81-3.27). This HR estimate shrunk to 2.03 (95% CI: 0.26-2.21) in the associated bootstrapping analysis and 3.09 in the associated highest penalty ridge regression analysis but was still found to be statistically significant. Inhibitor status was not found to be statistically associated with ICH. Results related to an interaction between prophylaxis and inhibitor status (Table 2) could not be interpreted because of the small sample size. Discussion ICH is a serious, life-threatening complication for PWHA, hence the need to identify factors associated with increased risk of ICH. This is the first study in a decade evaluating key demographic, clinical, and HA treatment characteristics for associated risk of PWHA developing ICH. These results demonstrate that risk factors for ICH include age (greatest risk in children between the ages of 2 and 12 years), having ever been on Medicaid, having had HIV, HCV, or HTN comorbidities, and never having received FVIII or prophylactic treatment. It was previously shown that prophylaxis confers a protective effect against ICH in instances of severe disease (Witmer 2010) and in children and adolescents (Andersson. Br J Haematol. 2017). Inhibitor positivity has been shown to increase risk for ICH (Witmer 2010; Zanon. Haemophilia. 2012); however, this study was unable to corroborate those findings. A larger sample size is required to draw substantive conclusions regarding the joint impact of prophylaxis and inhibitor status on risk of ICH. As the treatment landscape for HA evolves with the increased use of non-factor products and gene therapy, continued evaluation of risk factors for ICH will be needed. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Resection and total femoral prosthesis reconstruction treatment of massive femoral hemophilic pseudotumor: A case report.

Introduction and importanceHemophilic pseudotumor is a rare and serious complication of hemophilia, often occurring in the long bones and muscle tissue of the extremities, with an incidence of about 1–2%. However, there is no effective surgical treatment for massive hemophilia pseudotumors of the extremities. Therefore, we would like to report this case to provide new ideas and methods for the treatment of massive hemophilic pseudotumors of the extremities through resection and total femoral prosthesis reconstruction.Case presentationAfter admission, the patient first underwent a month-long coagulation factor replacement therapy to maintain the patient's factor IX level at approximately 100%. Then, extensive resection of hemophilic pseudotumor and total femoral prosthesis reconstruction was performed in collaboration with several departments, and we collected the patient's preoperative, intraoperative and postoperative data for analysis.Clinical discussionAfter coagulation factor replacement therapy the patient's factor IX level was significantly increased and approached 100%. The surgical procedure was uneventful, and postoperative X-ray suggested a well-positioned prosthesis with postoperative pathological features consistent with a hemophilic pseudotumor. The patient was able to move around with the assistance of a walker 14 days after surgery, and there was no recurrence after one year of follow-up.ConclusionFor treat the massive hemophilic pseudotumors of the extremities, extensive resection and prosthetic replacement with coagulation factor replacement therapy is a safe and effective treatment that can significantly improve the prognosis and quality of life of patients.

Trends of outcomes and healthcare utilization following orthopaedic procedures in adults with haemophilia: A 3-decade retrospective review.

Haemophilic arthropathy is a serious complication of haemophilia often requiring surgical intervention. It is unclear whether advances in comprehensive care are associated with a reduction in orthopaedic interventions and peri-procedural resource utilization. To determine temporal patterns of orthopaedic interventions in persons with haemophilia (PWH), and evaluate changes in healthcare utilization and outcomes. In this Canadian multicentre retrospective cohort study, adult PWH from Northern Alberta and British Columbia who underwent orthopaedic procedures (1990-2018) were included. Temporal changes in the type of procedures, length of stay (LOS), factor utilization and outcomes were examined. Sixty-five patients (78% haemophilia A) underwent 102 surgeries at a median age of 46.3. Of the 46 severe PWH, 28 (61%) were on prophylaxis at time of surgery. The proportion of total knee arthroplasties (TKA) declined over time (56% 1990-1999, 51% 2000-2009, 27% 2010-2018), with a concomitant rise in ankle arthrodesis (0% 1990-1999, 18% 2000-2009, 27% 2010-2018). Over time, PWH underwent orthopaedic procedures at an older age (P=.02). There was a significant reduction in perioperative factor VIII utilization (P=.003) and median LOS (P<.0001). Major bleeds, prosthetic joint infections and thrombosis were not observed in the last decade. In the last three decades, there was a decline in the proportion of TKA, likely reflecting the impact of widespread use of tertiary prophylaxis. However, ankle arthrodesis rates increased, suggesting that higher trough levels may be required to prevent ankle arthropathy. We observed a significant reduction in LOS and factor utilization, reflecting improvements in perioperative management.

FVIII Proteins with a Modified Immunodominant T-Cell Epitope Exhibit Reduced Immunogenicity and Normal Procoagulant Activity

Factor VIII (FVIII) neutralizing antibodies (inhibitors) are a serious complication in hemophilia A (HA). The peptide FVIII2194-2213 (legacy FVIII numbering, sequence: SYFTNMFATWSPSKARLHLQ) has been shown to contain an immunodominant HLA-DRA*01-DRB1*01:01 (DRB1*01:01)-restricted epitope recognized by CD4+ T-effector cells isolated from HA subjects. The aim of this study was to identify amino acid substitutions to de-immunize this epitope while retaining pro-coagulant function and expression levels comparable to those of wild-type (WT) FVIII proteins. The minimal DRB1*01:01-binding motif was mapped to FVIII2194-2205 by quantitative peptide-MHC Class II (MHCII) binding assays. Further binding assays with sequence-modified FVIII peptides established that the residues important for DRB1*01:01 affinity were F2196, M2199, A2201, and S2204, corresponding to MHCII anchor positions 1, 4, 6 and 9. T-cell proliferation experiments with Ala-substituted FVIII2194-2205 peptides identified F2196A as a substitution that abrogated proliferation and cytokine secretion of five clones specific for FVIII2194-2213. The substitution F2196A was then engineered into a recombinant (r)FVIII-C2 protein. T-cell clones that were strongly stimulated by wild-type rFVIII-C2 did not proliferate when cultured with rFVIII-C2-F2196A, indicating the immunogenic synthetic peptide includes a naturally processed T-cell epitope. The measured and predicted effects of additional amino acid substitutions within this binding motif were further evaluated by peptide-MHCII binding assays, CD4+ T-cell proliferation assays, and MHCII-binding prediction algorithms. Amino acid homologs within this binding motif were evaluated with sequence homologies to FVIII and FV proteins from different species. On the basis of all these results, six rB-domain-deleted (BDD)-FVIII proteins with amino acid substitutions F2196A, F2196L, F2196K, M2199A, M2199W or M2199R, respectively, were designed and produced; all but the F2196A variant had specific activities comparable to that of rWT-BDD-FVIII. The F2196A variant also had the lowest expression level among the rBDD-FVIIII proteins produced. Peptide-MHCII binding assays confirmed that FVIII2194-2205 peptides with substitutions F2196A, F2196K, M2199A and M2199R did not bind to DRB1*01:01 or to an additional 9 HLA-DR proteins tested, with the exception of the M2199A peptide binding to DRB1*09:01. The predicted effects of these FVIII sequence modifications on binding to additional MHCII alleles included in reference sets representing ~99% of the human population HLA diversity were evaluated using ProPred and Immune Epitope Database algorithms. These programs correctly predicted that the substitutions would abrogate binding to DRB1*01:01 and also indicated that affinities for additional MHCII would be reduced by each substitution. The substitutions were predicted to increase peptide-MHCII affinities for a smaller number of MHCII alleles, indicating a possible risk of creating neo-epitopes restricted to these specific HLA alleles. Importantly, proliferation of patient-derived T-cell clones in response to rBDD-FVIII-F2196K and rBDD-FVIII-M2199A proteins was dramatically reduced compared with responses to rWT-BDD-FVIII. We have previously demonstrated that a severe HA inhibitor subject had an oligoclonal T-cell response to only one T-cell epitope within the FVIII A2, C1 and C2 domains and that one epitope was FVIII2194-2213 (Ettinger et al., Blood 2106; 128(16):2043). This observation, together with the results presented here, further suggests that modification of only a small number of immunodominant epitopes may be sufficient to significantly de-immunize FVIII and decrease FVIII inhibitors in HA patients. The present results provide proof-of-principle for the design of less immunogenic FVIII proteins targeted to specific subsets of HA patients. DisclosuresEttinger:Bloodworks NW: Patents & Royalties: Inventor on FVIII patents. James:Bloodworks NW: Patents & Royalties: inventor on FVIII patent(s). Pratt:Bloodworks NW: Patents & Royalties: inventor on FVIII patents.

Immun Tolerance Induction in Hemophilia with Inhibitors: Istanbul Experience

Introduction: The development of inhibitors against factor VIII or IX is the most serious complication in hemophilia, occurring in approximately 30% and 5% of severe hemophilia A and B patients, respectively. Management of hemophilia with inhibitors presents certain challenges. The best treatment strategy for inhibitor eradication is immune tolerance induction (ITI). The aim of this study was to evaluate patients who were treated by ITI at our center.Material-Method: A retrospective data collection and analysis of patients were obtained. Data from all subjects with Hemophilia A with inhibitors undergoing ITI between 1999 and 2017 were collected from Istanbul University Hemophilia Centre.Results: Fifteen patients with severe Hemophilia A were enrolled in the study of whom 13 were eligible for analysis. After the exclusion of ineffective ITI treatments, median age of the beginning ITI was 10 years old (range:1,25-52), median maximum inhibitor titer before ITI was 30 BU (range:4.48-135) and during ITI was 3,4 BU (range:0-158.7). Median inhibitor titre was 1.25 BU (range:0-5.6) at the beginning of ITI. Median time interval between inhibitor development and starting of ITI was 5 years (range:0.58-22). In totally, 4 of the 12 patients (33.3%) had complete response, 2 of 12 (16.6%) had partial response and 2 of 12 (16.6%) had decreasing of inhibitor titer and ITI is going on. Four of the 12 patients (33.3%) had failure of ITI.Conclusion: Management of hemophilia with inhibitors presents certain challenges. Immun tolerance induction is the best treatment model. But high-dose daily regimen ITI could not be given in Turkey due to high cost of treatment. Our results showed that low dose ITI could be a choice for patients with inhibitors. DisclosuresNo relevant conflicts of interest to declare.

Observational Study of Recombinant Factor-VIII-Fc, Eloctate, in Hemophilia Patients with and without Inhibitors

Background: Inhibitor formation is a serious complication of hemophilia A, occurring in up to 30% with severe disease. It is associated with a T-cell response to infused factor VIII which neutralizes and renders it ineffective. Bypass therapy (rVIIa, FEIBA) is less effective, resulting in high morbidity and mortality. While immune tolerance (ITI) with high-dose FVIII neutralizes the inhibitor, it is costly, invasive, and unsuccessful in 30%. Basic studies suggest rFVIIIFc, Eloctate, is less immunogenic than standard recombinant FVIII, rFVIII, as the Fc portion contains regulatory T cells that promote tolerance. In the hemophilia mouse model, rFVIIIFc reduces inhibitor frequency, lowers titer, and shortens ITI, but little is known of its impact on inhibitor patients, as they were excluded from clinical trials.Methods: We, therefore, reviewed outpatient medical records on 60 patients with hemophilia A with and without inhibitors, cared for at the Hemophilia Center of Western Pennsylvania between January 1, 2006 and June 1, 2017, who were treated with rFVIIIFc and on whom anti-FVIII inhibitor assay results were available. This study was approved by the University of Pittsburgh IRB as an expedited study, PRO17020097. Means, medians, and standard deviations or frequencies (percentages) were determined for clinical variables, including age, race, proportion developing inhibitors, peak titer, proportion achieving tolerance, and time to tolerance on ITI. Comparisons between patients with high-titer, low-titer, and no inhibitors were by student's t test for continuous data, or chi-square or Fisher's exact test for discrete data. A p-value of < 0.05 was considered statistically significant.Results: The 60 patients whose charts were reviewed for this study included 18 (30.0%) with hemophilia A with an inhibitor (HA-I), of whom 9 had high-responding inhibitors (≥5 BU) and 9 had low-responding inhibitors (<5 BU); and 42 (70.0%) with hemophilia A without an inhibitor (HA). HA-I were similar to HA in age, with 44.4% vs. 50.0% ≥ 18 years of age, respectively, p>0.5, and in disease severity, 83.3% vs. 64.2% < 0.01 IU/dL, p=0.105, but a greater proportion were black, 16.7% vs. 4.8%, p=0.007, and had an intron 22 inversion mutation, 37.5% and 19.2%, p=0.001 (Table). The majority of both groups were previously treated patients (PTPs), 17 of 18 HA-I (94.4%) vs. 41 of 42 HA (97.6%). Following initiation of rFVIIIFc, none of 42 HA, 0/42 (0%) developed inhibitors, while, by contrast, inhibitors were detected in 6 of 18 (33.3%) HA-I, p=0.002. The 6 patients developing inhibitors after rFVIIIFc included 5 PTPs and 1 PUP: the single PUP was from an inhibitor-prone kindred with an exon 14 nonsense variant (75% inhibitor risk) (Haemophilia, 2016), and developed a low-responding inhibitor, 1.4 BU, after 10 exposures to rFVIIIFc, which resolved to <0.6 BU within 1 month while continuing rFVIIIFc. The 5 PTPs developing inhibitors on rFVIIIFc included 4 of 9 (44.4%) previous high-responding inhibitors (≥5 BU) and 1 of 8 (12.5%) previous low-responding inhibitors (<5 BU). All 4 past high-responders had previously failed or had never undergone immune tolerance induction (ITI); while the single past low-responder had longstanding fluctuating low-level inhibitor titers. Following initiation of rFVIIIFc, the 4 PTPs with past high-responding inhibitors developed inhibitors, median anti-FVIII = 40 BU (0-87.7), which resolved, in all 4, to anti-VIII <0.6 BU after a median 2.2 months (1-13) while continuing rFVIIIFc; the 1 PTP with a past low-responding inhibitor and chronic fluctuating low-level inhibitor, developed a low-responding inhibitor 0.6 BU (0-0.6 BU), which resolved to <0.6 BU while continuing rFVIIIFc, but continues to fluctuate between 0 and 0.6 BU.Discussion: These findings indicate that PTPs without inhibitors or with tolerized inhibitors do not develop inhibitors after switching to rFVIIIFc. By contrast, most PTPs with high-responding inhibitors who failed or never underwent ITI, develop inhibitor recurrence after switching to rFVIIIFc, but these are rapidly tolerized while continuing rFVIIIFc. In PTPs with low-responding inhibitors, rFVIIIFc may reduce but does not eliminate fluctuating low-level titers. Finally, in PUPs at risk for inhibitor formation, rFVIIIFc may induce low-responding low-titer inhibitors which are rapidly tolerized while continuing rFVIIIFc. [Display omitted] DisclosuresRagni:SPARK: Research Funding; NovoNordisk: Honoraria; Alnylam: Consultancy, Honoraria, Research Funding; Sangamo: Research Funding; Genentech/Roche: Research Funding; Bioverativ: Consultancy, Honoraria, Research Funding; MOGAM: Consultancy, Honoraria; Bayer: Consultancy, Honoraria, Research Funding; Biomarin: Consultancy, Honoraria, Research Funding; Shire: Consultancy, Honoraria, Research Funding. Malec:Bioverativ: Consultancy, Research Funding.

Cost-effectiveness of emicizumab vs bypassing agents in the prevention of bleeding episodes in haemophilia A patients with anti-FVIII inhibitors in France.

The development of an anti-FVIII inhibitor is the most serious complication of haemophilia A occurring in up to 30% of severe haemophilic patients. The current management of haemophilia A with inhibitor uses bypassing agents (BPA) and represents a significant therapeutic burden together with a limited adherence to prophylactic treatment. Emicizumab is the first monoclonal antibody developed in haemophilia A approved for the prevention of bleeding episodes in patients with anti-FVIII inhibitor. The purpose of this study is to evaluate the incremental cost-effectiveness ratio (ICER) of emicizumab versus BPAs. A Markov model was developed over a five-year time horizon to estimate the comparative costs and benefits of the different therapeutic approaches in this rare disease. Model inputs were clinical, including annual bleeding rate and quality of life, and economical including mainly costs of prophylaxis, bleeds and adverse events. Emicizumab treatment is dominant, ie lest costly and more effective, in the base-case analysis saving 234191 € for a gain of 0.88 QALY. This is confirmed by both the deterministic and probabilistic sensitivity analyses. The main limit of the study remains the absence of long-term clinical data allowing to relate treatment consumption to clinical benefit, especially in the progression of haemophilic arthropathy. Our results show that emicizumab is a cost-effective treatment allowing to consider an easy to implement prophylactic treatment for haemophilia A patients with anti-FVIII inhibitors.

Gut dysbiosis modulates the immune response to factor VIII in murine hemophilia A

AbstractThe development of neutralizing FVIII antibodies is the most serious complication of hemophilia A treatment. The currently known patient- and treatment-related risk factors for inhibitor development do not accurately predict this adverse event in all patients. The composition of the gut microbiota has been shown to influence immune-mediated diseases at distant anatomical sites (eg, lungs, brain, and joints). We demonstrate that a disrupted gut microbiota can be created in a mouse model of hemophilia A using a broad-spectrum antibiotic. Under controlled conditions, this sustained dysbiosis was associated with an increase in splenic B cells and the development of higher titer, FVIII-specific immunoglobulin G antibodies after FVIII challenge. Splenic and mesenteric lymph node cytokines, T cells, and dendritic cells were unaffected before administration of FVIII. However, the immune transcriptome of both aforementioned secondary lymphoid organs was significantly modified. Short-chain fatty acids (SCFAs), which are immunomodulatory microbial metabolites, were depleted in cecal contents of the dysbiotic mice. Furthermore, supplementation of the drinking water with butyrate, the most immunologically active SCFA, successfully achieved attenuation of the FVIII immune response. Collectively, data from this exploratory study suggest that the composition of the gut microbiota alters the FVIII immune response via the action of specific microbial metabolites on the immune cell transcriptome and that oral supplementation with butyrate effectively reduces the FVIII immune response.

Immune Tolerance Induction (ITI) with a Plasma-Derived Factor VIII for Patients with Hemophilia a and Inhibitors: A Retrospective Study

Introduction: A serious complication in hemophilia A is the formation of inhibitors to clotting factors. The primary means for eradicating inhibitors is immune tolerance induction (ITI) therapy. Antihemophilic factor (human) (Koate®-DVI) is a purified dried concentrate indicated for the treatment of hemophilia A with insufficient activity of Factor VIII (FVIII). Although other plasma-derived concentrates containing von Willebrand factor have been utilized successfully for ITI, studies evaluating this product for ITI therapy have not been published. An evaluation of patient- and treatment-related factors associated with outcomes following primary or rescue ITI with antihemophilic factor (human) in patients with hemophilia A and inhibitors was conducted in this retrospective multicenter chart review project. Methods: An evaluation of medical records of 13 inhibitor patients treated with antihemophilic factor (human) for primary or rescue ITI therapy between January 1, 2012, and July 31, 2017, was conducted in five US hemophilia treatment centers. To be eligible for inclusion, patients were required to have a diagnosis of hemophilia A of any severity level, inhibitor to FVIII at the time of treatment initiation with antihemophilic factor (human), and ongoing treatment with antihemophilic factor (human) for primary or rescue ITI. Data were de-identified and analyzed descriptively. Outcome measures were defined, per the International Immune Tolerance consensus recommendations, as "complete success" (inhibitor titer &lt;0.6 Bethesda Units [BU] at 33 months of ITI, FVIII recovery ≥66% and half-life ≥6 hours), "partial success" (a reduction in inhibitor titer to &lt;5 BU mL with FVIII recovery &lt;66% and/or FVIII half-life &lt;6 hours associated with clinical response to FVIII therapy not followed by a treatment-limiting anamnestic rise in inhibitors to &gt;5 BU mL), or "failure" (neither complete nor partial success). Results: All (N=13) patients who met the inclusion criteria were males with severe hemophilia, with the exception of one with moderate hemophilia. Six patients were African American, four were Hispanic, two Caucasian, and one was Asian. They were diagnosed with inhibitors between the ages of 8 months and 39 years and were 5 to 53 years old upon ITI with antihemophilic factor (human). Ten of 13 patients (76.9%) had successful ITI; seven with complete success and three with partial success (Table). Three patients failed ITI. As primary therapy, complete success was obtained with all but one of the six patients treated with antihemophilic factor (human). These six patients were all older than 7 at the initiation of ITI, a risk factor for poor ITI. Seven of the 13 total patients had a combined previous 12 attempts at ITI with other products (plasma derived and/or recombinant). Of these seven rescue patients, ITI with antihemophilic factor (human) was completely successful in two and partially successful in three. Adverse events reported once in separate patients during treatment with antihemophilic factor (human) included catheter infection, portal infection, bacteremia, peritonitis due to a ruptured appendix, and complications in treatment. One patient had several adverse events, including cellulitis at the port site, abdominal wall hematoma, right thumb fracture and hematoma, and left shoulder hemarthrosis. Conclusions: While retrospective data has limitations, real-world evidence demonstrates that ITI with antihemophilic factor (human) concentrate can be successful or partially successful in diverse populations of moderately complex patients with hemophilia A and inhibitors. The data suggest that antihemophilic factor (human) may be most appropriate for patients when used as primary ITI, as even patients older than 7 years achieved complete success. Additional patients need to be evaluated to make a definitive conclusion regarding the impact of age on success of ITI therapy in addition to other risk factors. Disclosures Escobar: Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; National Hemophilia Foundation: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees. Rajan:Bayer, Octapharma: Consultancy, Honoraria, Research Funding, Speakers Bureau. Amega:Kedrion Biopharma: Employment. OffLabel Disclosure: Koate is not approved to treat vWD, nor, cTTP however, based on some published reports using kotae for these indications, we are anticipating those type of off label inquiries. I will clearly disclose to the participants that these are off label indications.

PRO34 COST-EFFECTIVENESS OF EMICIZUMAB VERSUS BY-PASSING AGENTS IN PATIENTS WITH HAEMOPHILIA A AND FVIII INHIBITORS IN FRANCE.

The development of an anti-FVIII inhibitor is the most serious complication of haemophilia A. Since February 7th 2019, emicizumab is reimbursed in France for the prevention of bleeding episodes in patients with haemophilia A with FVIII inhibitor. The purpose of this analysis is to evaluate the Cost-Effectiveness of emicizumab compared to the current management by Bypassing Agents (BPAs) in France, taking into account the final public price granted. The analysis is based on a Markov model with two health states over a 5-year time horizon. Emicizumab is compared with BPAs (aPCC and rFVIIa) in prophylaxis or on-demand, according to their real-life use in the FranceCoag Network cohort (RFC). The ICER is expressed in euros per QALY (Quality-Adjusted Life Year). Bleeding rates are derived from the HAVEN 1 clinical trial for emicizumab and BPA on-demand, and an indirect comparison for BPA prophylaxis. Quality of life data are derived from the HAVEN 1 trial. The costs of treatment, adverse events and hospitalizations were included. Various sensitivity analyses were performed to evaluate the uncertainty around the result. Emicizumab prophylaxis is a dominant strategy: it is more effective and less costly than BPAs. Over 5 years, the mean total cost per patient was 2,3 M€ in patients treated with emicizumab, versus 2,6 M€ with BPA, associated to 3,3 and 2,4 QALYs respectively. Thus, emicizumab brings 0,9 additional QALYs per patients for a saving of 283 642€. Exploration of uncertainty does not alter these results. The health economic analysis shows the cost-effectiveness of emicizumab versus BPA in France. The methodology used was accepted by the CEESP in its Opinion of October 9, 2018. The limitations of this analysis are mainly based on the lack of data to model the consequences of the reduction of bleeding on the long-term evolution of arthropathy and disability.

PF331 COST‐EFFECTIVENESS OF EMICIZUMAB VERSUS BY‐PASSING AGENTS IN PATIENTS WITH HAEMOPHILIA A AND FVIII INHIBITORS IN FRANCE

Background:The development of an anti‐FVIII inhibitor is the most serious complication of haemophilia A. On February 23, 2018, Emicizumab obtained a European Marketing Authorization for the prevention of bleeding episodes in patients with haemophilia A who developed an anti‐FVIII inhibitor. In France, emicizumab is reimbursed by National Insurance since February 7th2019. As part of its inscription on the list of products reimbursed by French National Health Insurance, emicizumab has been evaluated by health authorities (HAS): The Transparency Committee granted a major added medical benefit (ASMR II), and a medico‐economic analysis was evaluated by the Health Economic and Public Health Committee.Aims:The purpose of this analysis is to evaluate the Incremental Cost‐Effectiveness Ratio (ICER) of emicizumab compared to the current management by Bypassing Agents (BPA) taking into account the final price that has just being published.Methods:The analysis is based on a Markov model with two health states (alive, dead) over a 5‐year time horizon. Emicizumab is compared with current BPA management (aPCC and rFVIIa) in prophylaxis or on‐demand, according to their real‐life use in the FranceCoag Network cohort (RFC). The ICER is expressed in euros per QALY (Quality‐Adjusted Life Year). Bleeding rates are derived from the HAVEN 1 clinical trial for emicizumab and BPA on‐demand, and an indirect comparison for BPA prophylaxis. Quality of life data are derived from the HAVEN 1 trial. The costs of treatment acquisition, adverse events and hospitalizations were taken into account. Deterministic and probabilistic sensitivity analyzes were performed to evaluate the uncertainty around the result.Results:Emicizumab prophylaxis is a dominant strategy, in children and adult patients: it is more effective and less costly than the current BPA strategy. Over 5 years, the mean total cost per patient was 2,3 M€ in patients treated with emicizumab, versus 2,7 M€ with BPA, associated to 3,3 and 2,4 QALYs respectively. Thus, emicizumab brings 0,9 additional QALYs per patients for a saving of almost 426 000€. Exploration of uncertainty does not alter these results.Summary/Conclusion:The health economic analysis shows the cost‐effectiveness of emicizumab versus BPA in France. The methodology used was accepted by the CEESP in its Opinion of October 9, 2018. The limitations of this analysis are mainly based on the lack of data to model the consequences of the reduction of bleeding on the long‐term evolution of arthropathy and disability.

Successful of Immune Tolerance Induction (R-ITI) with Simoctocog Alfa (rhFVIII) in Hemophilia a Patients and High-Titer Inhibitors

Backgroud: The appearance of inhibitors (INH) is the most serious complication in hemophilia A (HA) patients. The primary objective is their eradication. Usually the primary ITI was performed with the same concentrate causing INH development, but which replacement factor to be use in case of ITI-R is still debatable. We report two successful cases of ITI-R with simoctocog alfa (rhFVIII) performed in two different Italian Hemophilia Centers, while three other cases are still ongoing. Case Report: Case-1: Adult man with moderate HA who developed INH after surgery and concomitant switch to another concentrate (octocog-alfa 2nd gen). The patient refused the ITI treatment immediately after the inhibitors appearance, and was then put on prophylaxis with bypassing agents for several months. First ITI was then started with pdFVIII/vWF at 200 IU/kg/day, inhibitor titer reached its historical peak (134 BU/ml) two months later and progressively decreased to 15 BU/ml, but without ever disappearing. This ITI was stopped after nineteen months. A second ITI was then tried with high dose regimen of morocotocog-alfa, but also in this case the mean INH titer remained steadily high (21 BU/ml) and this treatment was considered failed after fifteen months from the onset. A new ITI-R was then started when the INH titer was 74 BU/ml, with simoctoctocog-alfa (rhFVIII), at 200 IU/kg/day. INH progressively decreased and 7 months later disappeared ( Disclosures No relevant conflicts of interest to declare.

Correlations of Plasma Cytokine Levels and Anti-FVIII Antibodies during Immune Tolerance Induction

IntroductionThe development of neutralizing anti-FVIII antibodies (inhibitors) with reduced or absent activity of substituted factor VIII (FVIII) remains the most serious complication of hemophilia A therapy (Kempton, 2014). Frequent and high doses of FVIII with or without bypassing products can reestablish immune tolerance in 60-70% of patients. Polymorphism in immune response genes including IL-10 and TNFa were identified as risk factors for inhibitor development (Astermark, 2006). Cross-sectional studies showed different cytokine profiles in patients with hemophilia, especially in those with history of an inhibitor (Oliveira, 2013). In this study cytokine profiles were monitored longitudinally during immune tolerance induction (ITI).Methods107 plasma samples from 18 patients were collected during the RES.I.S.T Experienced and Naive trial, which included patients with a poor prognosis for ITI success (Gringeri, 2007). We quantified 14 cytokines in each sample by using a Human High Sensitivity T-Cell Discovery Array 14-Plex (Eve Technologies Corp, Calgary, AB, Canada). ELISA based FVIII antibody assays were used for anti-FVIII IgG detection. FVIII inhibitor titers (Bethesda assay, BU) were measured and available for the analysis. The cut-off for a positive inhibitor was >0,6 BU mL-1. Bethesda titers (BUpos) between 0,6 - <5,0 were considered as low titer (BUlow), whereas BU ≥5 as high titer (BUhigh). Statistical analyses were performed using GraphPad Prism 7. Mann-Whitney U tests and Spearman correlation tests considered significant when P value <0.05.ResultsPlasma levels of TNFa (P=0,014) and IL-8 (P=0,048) were positively correlated with FVIII inhibitor titers. Negative correlation was found in levels of IL-10 (P=0,041), IL-12 (P=0,038) and IL-1B (P=0,026). When cytokine levels of plasma samples with detectable and undetectable FVIII inhibitor titers were compared, significant higher plasma levels of TNFa (median: 11,56pg/ml, 8,11pg/ml; P=0,016) and lower levels of IL-12 (median: 4,29 pg/ml, 6,25 pg/ml; P=0,047) and IL-23 (median: 1016 pg/ml, 1353 pg/ml; P=0,049) were measured in samples with detectable FVIII inhibitor (BUpos). Furthermore, TNFa levels were higher in BUlow (median: 10,83 pg/ml; P=0,047) as well as in BUhigh samples (median: 11,75 pg/ml; P=0,019), compared to BUneg (median: 8,11 pg/ml). Cytokine concentrations of IL-1B (median: 2,64 pg/ml, 3,77 pg/ml; P=0,023), IL-2 (median: 2,44 pg/ml, 2,97pg/ml; P=0,043) and IL-17 (median: 15,79 pg/ml, 19,42 pg/ml; P=0,036) were significantly lower in BUhigh plasma samples compared to BUneg. Additionally, plasma level of IL-10 correlated negatively with levels of anti-FVIII IgG (P=0.045).ConclusionThis is the first study of cytokine measurement in a longitudinal setting as well as during ITI in patients with hemophilia. FVIII inhibitors and anti-FVIII IgG antibodies were correlated to IL-10 and TNFa levels - of note, polymorphisms in the genes of these cytokines are a known risk factor for inhibitor development. Furthermore, IL-12, IL-17 and IL-23 levels were higher in samples with loss of FVIII Inhibitors. In addition to prediction of inhibitor development, cytokine profiles might serve as prognostic factors for ITI success and considering the emerging evidence of the IL-17-IL-23 immune axis in autoimmunity might also be promising therapeutic approaches for higher ITI success rates. DisclosuresEwing:Genentech: Honoraria; Shire: Honoraria; Bayer: Honoraria; Grifols: Honoraria; CSL Behring: Honoraria; Novo Nordisk: Honoraria; Hema Biologics: Honoraria; Biogen: Research Funding. Koenigs:Jansen: Research Funding; Gilead: Research Funding; Biotest: Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau; Pfizer: Research Funding, Speakers Bureau; Intersero: Research Funding; CSL Behring: Consultancy, Research Funding; EU (IMI, FP7): Research Funding; Sobi: Consultancy, Research Funding, Speakers Bureau; Shire: Consultancy, Research Funding; Novo Nordisk: Consultancy, Speakers Bureau; Bioverativ: Consultancy; Roche/Chugai: Consultancy.

Immune Tolerance Induction with Simoctocog Alfa (Nuwiq®) in Six Patients with Severe Haemophilia a and FVIII Inhibitors

Introduction and Objective: Inhibitors to coagulation factor VIII (FVIII) are the most serious complication of haemophilia A treatment. Previously untreated patients (PUPs) are at the greatest risk of inhibitors, which generally occur within the first 20 exposure days (ED) to FVIII. Immune tolerance induction (ITI) is the only clinically proven strategy for eradication of inhibitors. We present a case series of six PUPs with severe haemophilia A and inhibitors who underwent ITI with simoctocog alfa (Nuwiq®), a 4th generation human cell-line-derived recombinant FVIII approved for treatment of haemophilia A.Materials and Methods: Six male PUPs with severe haemophilia A who developed FVIII inhibitors after treatment with simoctocog alfa were started on ITI with simoctocog alfa. Primarily, we assessed the success of simoctocog alfa in patients with inhibitors. Success of ITI was determined based on undetectable inhibitor titre (< 0.6 BU/ml), FVIII recovery ≥ 66% and half-life ≥ 6 hours. Secondary objectives were to assess bleeding rate, tolerability and safety in patients with inhibitors treated with simoctocog alfa ITI.Results: The age of the patients at the start of ITI ranged from 8 to 186 months. Four of the patients were Caucasian, and two were African. All patients had a F8 mutation associated with high risk of ITI failure and two patients had an additional risk factor for ITI failure. The number of EDs prior to inhibitor development ranged from 9 to 33, and the peak inhibitor titre ranged from 0.9 to 114 BU. For ITI, five patients were treated with 100 IU/kg simoctocog alfa daily, and one with 90 IU/kg every other day. One patient achieved complete tolerisation and is now on prophylaxis at normal doses, having achieved an undetectable inhibitor titre after 9 months. This was despite an inhibitor titre ≥ 10 BU/mL at ITI start, which is considered a poor prognosis factor for ITI success. Three other patients achieved an undetectable inhibitor titre after 1, 6 and 18 months of ITI, and FVIII recovery has normalised but half-life remains short and they are on weaning doses as the half-life extends. One patient discontinued ITI with simoctocog alfa after 15 months due to an increasing inhibitor level. This patient was 15 years old at ITI start, and older age is associated with poor ITI outcome. Additionally, his haemophilia A was untreated for 15 years, during which time he developed severe arthropathy. One patient, who started ITI 3 months ago, has an ongoing inhibitor titre and continues on ITI with simoctocog alfa.Conclusions: In a case series of six patients treated with simoctocog alfa for ITI, who all had poor prognosis factors for ITI success, four patients (67%) to date have achieved an undetectable inhibitor titre. These data suggest that ITI with simoctocog alfa may be an effective treatment approach in haemophilia A patients with inhibitors. DisclosuresKhair:Shire, SOBI, Pfizer, Roche, Novo Nordisk, Octapharma: Speakers Bureau; shire, SOBI, Pfizer, Roche: Research Funding. Liesner:Roche: Research Funding; Novo Nordisk: Research Funding, Speakers Bureau; Baxalta: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; Octapharma: Consultancy, Other: Clinical study investigator for NuProtect Study (Octapharma sponsored), Research Funding, Speakers Bureau; Sobi: Speakers Bureau. Belyanskaya:Octapharma AG: Employment.

Immune tolerance induction: What have we learned over time?

Development of inhibitory antibodies to infused factor VIII (FVIII) concentrates continues to be the most serious complication of haemophilia A management. Induction of immune tolerance by administering high doses of FVIII concentrate (antigen) and prothrombin complex concentrates to control bleeding was originated in the 1970s in Bonn, Germany, by Dr Hans-Hermann Brackmann, and became known as the Bonn protocol. ITI transformed the life of the index patient, who was 19years of age when he began treatment, and dramatically improved the medical landscape for all patients with haemophilia and inhibitors. Over the past 40years, variations to the Bonn protocol have been proposed. All protocols are effective although some are better suited than others for use in certain situations. The specific molecular defect in FVIII and the human leucocyte antigen (HLA) type of an individual with haemophilia are major codependent determinants to inhibitor development. Given the range of potential molecular defects and the staggering number of potential HLA types, it is likely that treatment arms of randomized studies in haemophilia represent highly diverse populations, which reduces the power of a study to demonstrate differences between treatments. Although available clinical guidelines and consensus recommendations for ITI therapy are not always in complete agreement, collectively the guidelines provide a reasonable level of guidance for administering ITI therapy under different clinical scenarios. Several studies of ITI therapy are ongoing with the aim of clarifying unresolved issues in haemophilia management including the role of von Willebrand factor in inhibitor eradication.

Early cellular interactions and immune transcriptome profiles in human factor VIII‐exposed hemophilia A mice

Background Developing factor VIII (FVIII) inhibitory antibodies is the most serious complication in hemophilia A treatment, representing a significant health and economic burden. A better understanding of the early events in an immune response leading to this outcome may provide insight into inhibitor development. Objective To identify early mediators of FVIII immunity and to detail immune expression profiles in the spleen and liver. Methods C57Bl/6F8 E16 knockout mice were infused with 5-20μg (2000-8000IUkg-1 ) of recombinant FVIII. Spleens were frozen at various time-points post-infusion and stained for FVIII and cellular markers. Splenic and liver RNA expression analysis was performed 3h post-infusion of 0.6μg (240IUkg-1 ) FVIII by nCounter technology using a 561-gene immunology panel. Results FVIII localization in the spleen did not change over 2.5h. We observed significantly higher co-localization of FVIII with MARCO+ cells compared with SIGLEC1+ and SIGNR1+ in the splenic marginal zone. FVIII exhibited little co-localization with CD11c+ dendritic cells and the macrophage mannose receptor, CD206. Following FVIII infusion, the splenic mRNA profiling identified genes such as Tnfaip6 and Il23r, which are implicated in chemotaxis and a proinflammatory Th17 response, respectively. In contrast, an upregulation of Gfi1 in the liver suggests an anti-inflammatory environment. Conclusions FVIII co-localizes predominantly with marginal zone macrophages (MARCO+ ) in the murine spleen following intravenous infusion. Targeting pathways that are implicated in the early FVIII innate immune response in the spleen may lead to therapeutic interventions to prevent inhibitor formation.

FVIII proteins with a modified immunodominant T-cell epitope exhibit reduced immunogenicity and normal FVIII activity

AbstractFactor VIII (FVIII)–neutralizing antibodies (inhibitors) are a serious complication in hemophilia A (HA). The peptide FVIII2194-2213 contains an immunodominant HLA-DRA*01-DRB1*01:01 (DRB1*01:01)-restricted epitope recognized by CD4+ T-effector cells from HA subjects. The aim of this study was to identify amino acid substitutions to deimmunize this epitope while retaining procoagulant function and expression levels comparable to those of wild-type (WT) FVIII proteins. The shortest DRB1*01:01-binding peptide was FVIII2194-2205, and residues important for affinity were identified as F2196, M2199, A2201, and S2204. T-cell proliferation experiments with Ala-substituted FVIII2194-2205 peptides identified F2196A as a substitution that abrogated proliferation of clones specific for the WT sequence. T-cell clones that were stimulated by recombinant WT-FVIII-C2 (rWT-FVIII-C2) protein did not proliferate when cultured with rFVIII-C2-F2196A, indicating the immunogenic peptide includes a naturally processed T-cell epitope. Additional amino acid substitutions at F2196 and M2199 were evaluated by peptide-MHC class II (MHCII)–binding assays, T-cell proliferation assays, epitope prediction algorithms, and sequence homologies. Six B-domain–deleted (BDD)-FVIII proteins with substitutions F2196A, F2196L, F2196K, M2199A, M2199W, or M2199R were produced. Proliferation of T-cell clones and polyclonal lines in response to rBDD-FVIII-F2196K and rBDD-FVIII-M2199A was reduced compared with responses to WT-BDD-FVIII. The BDD-FVIII-F2196K sequence modification appears to be the most promising sequence variant tested here, due to its effectiveness at eliminating DRB1*01:01-restricted immunogenicity, low potential immunogenicity in the context of other MHCII alleles, expression level comparable to WT-BDD-FVIII, and retained procoagulant activity. These results provide proof of principle for the design of less immunogenic FVIII proteins targeted to specific subsets of HA patients.

Joint bleeds increase the inhibitor response to human factor VIII in a rat model of severe haemophilia A.

The most serious complication in haemophilia A (HA) replacement therapy with coagulation factor VIII (FVIII) is neutralizing antibodies, i.e. inhibitors. It has been hypothesized that danger signals generated during a bleed might have an adjuvant effect on the immune response to FVIII in on-demand treatment, increasing the inhibitor risk. To compare the antibody response to treatment with recombinant human FVIII (rhFVIII) in relation to induced knee joint bleeds and treatment without concurrent bleeds in a HA rat model. HA rats were divided into two groups: one group (n = 10) receiving three needle induced knee joint bleeds 14 days apart and a control group (n = 9) receiving three sham procedures. Three hours after each injury/sham 50 IU kg(-1) rhFVIII was administrated intravenously. Subsequently, both groups continued rhFVIII treatment for another 9 weeks. Binding antibodies were analysed using an enzyme-linked immunosorbent assay and neutralizing antibodies using a Bethesda-like assay. Rats in the knee-bleed group developed a significantly faster inhibitor response and reached significantly higher inhibitor levels. In the knee-bleed group, 80% developed inhibitors vs. 33% in the control group, demonstrating a 2.4 times higher inhibitor risk when treating concurrent with bleeds. FVIII treatment in relation to a bleed potentiates inhibitor development compared to FVIII treatment alone in this HA rat, indicating that bleeding is a potential danger signal. Our results support the theory that FVIII replacement therapy concurrent with a bleeding episode increases the inhibitor risk, which to the best of our knowledge, has not been confirmed in an animal model before.