Bleeding control improves after switching to emicizumab: Real-world experience of 177 children in the PedNet registry.

INTRODUCTION: Despite the rapid uptake of emicizumab in the paediatric haemophilia A (HA) population, real-world data on the safety and efficacy is limited. AIM: To report on bleeding and safety in paediatric patients receiving emicizumab prophylaxis. METHODS: Data were extracted from the multicentre prospective observational PedNet Registry (NCT02979119). Children with haemophilia A, and ≥50 FVIII exposures or inhibitors present receiving emicizumab maintenance therapy were analysed. Data were summarized as medians with interquartile range (IQR, P25-P75). Mean (95% confidence interval (CI)), annualized (joint) bleeding rate (A(J)BR) during emicizumab and ≤2 years before emicizumab prophylaxis were modelled and compared using negative binomial regression. RESULTS: Total of 177 patients started emicizumab at median 8.6 years (IQR 4.8-13.1), most had no FVIII inhibitors (64%). Follow up before emicizumab was median: 1.68 years (IQR: 1.24-1.90) and during emicizumab: 1.32 years (IQR: .94-2.11). In patients without inhibitors, mean ABR reduced after starting emicizumab from 2.41 (CI 1.98-2.95) to 1.11 (CI .90-1.36, p < .001), while AJBR reduced from.74 (CI .56-.98) to.31 (CI .21-.46, p < .001). Concordantly, in patients with inhibitors, mean ABR reduced from 5.08 (CI 4.08-6.38) to .75 (CI .56-1.01, p < .001), while AJBR reduced from 1.90 (CI 1.42-2.58) to .34 (CI .21-.56, p < .001). Five emicizumab-related adverse events were reported (3% of the cohort), including one patient with antidrug antibodies. CONCLUSION: This study showed improved bleeding control compared to previous treatment and a favourable safety profile during emicizumab therapy in paediatric haemophilia A patients.

Targeting an elevated FVIII level using personalized rurioctocog alfa pegol prophylaxis in specific patient populations with hemophilia A: post hoc subanalysis of the randomized, phase 3 PROPEL study.

Background: The phase 3, prospective PROPEL study demonstrated that pharmacokinetic (PK)-guided prophylaxis targeting elevated factor VIII (FVIII) troughs in patients with hemophilia A resulted in lower annualized bleeding rates (ABRs) and a higher proportion of patients experiencing zero bleeds in the second 6 months of treatment when targeting a FVIII trough of 8-12% versus 1-3%. Objective: To investigate the benefit of PK-guided prophylaxis with rurioctocog alfa pegol targeting two FVIII trough levels in specific patient subgroups in a post hoc analysis using data from PROPEL. Design: This is a post hoc analysis of data from the PROPEL study. The design and primary outcomes of the prospective, randomized PROPEL study (NCT02585960) have been reported previously. Methods: This post hoc analysis reports data stratified by FVIII half-life (t1/2), hemophilic arthropathy status, number of target joints at screening, previous treatment regimen, and ABR range in the 12 months before study entry. Results: Targeting an elevated FVIII trough of 8-12% was associated with higher average FVIII levels over time, regardless of FVIII t1/2 at baseline. The decrease in total ABR between the 8-12% and 1-3% arms was greatest in patients with a FVIII t1/2 of 6 to <12 h (0.7 versus 3.5); a higher number of target joints, that is, at least four target joints, at baseline (0.2 versus 1.6); the presence of arthropathy (0.1 versus 1.7); and those previously treated on-demand (0.3 versus 1.8). Conclusion: These results support the feasibility of targeting elevated FVIII levels using personalized rurioctocog alfa pegol prophylaxis. These benefits may be especially important in patients with a short FVIII t1/2 and those receiving standard prophylaxis with frequent breakthrough bleeds, arthropathy, and target joints. Registration: ClinicalTrials.gov Identifier: NCT02585960; https://clinicaltrials.gov/ct2/show/NCT02585960.

Immune Tolerance Induction (ITI) with a pdFVIII/VWF Concentrate (octanate) in 100 Patients in the Observational ITI (ObsITI) Study.

Background Immune tolerance induction (ITI) with repeated factor VIII (FVIII) administration is the only strategy proven to eradicate inhibitors. The observational ITI study is evaluating ITI with a range of FVIII products. Methods This subgroup analysis reports prospective interim data for patients treated with a plasma-derived, von Willebrand factor-stabilized FVIII concentrate (pdFVIII/VWF, octanate). Complete success (CS) of ITI required achievement of three criteria: inhibitor titer < 0.6 BU/mL; FVIII recovery ≥ 66%; FVIII half-life ≥6 hours. Partial success (PS) required achievement of two criteria and partial response (PR) one. ITI success was defined as CS or PS. Data were analyzed for patients who achieved CS, had 36 months' observation, or failed ITI. Results One-hundred prospectively enrolled patients were included in the analysis; 91 had poor prognosis factors for ITI success. The mean (standard deviation) daily ITI dose was 116.4 (61.1) IU FVIII/kg in 14 low responders (< 5 BU/mL) and 173.7 (112.0) IU FVIII/kg in 86 high responders (≥ 5 BU/mL). Inhibitor titers < 0.6 BU/mL were achieved in 71% of patients in a median of 4.01 months, accompanied by a 93% reduction in bleeding rate. ITI success was achieved by 70% of patients and 56 of 72 (78%) primary (first-line) ITI patients. PR was achieved by 5 patients; ITI failed in 25 patients. PS and CS were achieved in a median of 5.55 and 11.25 months, respectively. Conclusions ITI with pdFVIII/VWF led to rapid eradication of FVIII inhibitors, normalization of FVIII pharmacokinetics in the majority of patients, and a significant reduction in bleeding rates.

Inhibitors: Diagnostic challenges, unknowns of inhibitor development, treatment of bleeding and surgery, and insights into diagnosis and treatment in China.

Factor (F) VIII inhibitors develop in around 30% of previously untreated patients (PUPs) with severe haemophilia, to a lesser extend in moderate and mild haemophilia A and in up to 10% in severe haemophilia B. Diagnostic challenges and questions remain including access to high quality testing, the role for functional inhibitor testing and binding antibody testing, and the adaptations needed in the presence of non-factor replacement therapy. Despite significant gains in knowledge there are still many unanswered questions underlying the immunologic mechanisms of inhibitor development and tolerance. Therapeutic options include eradication of inhibitors using immune tolerance induction therapy (ITI), prophylaxis with bypassing agents (i.e., recombinant activated factor VII /rFVIIa or activated prothrombin complex concentrate/aPCC) or non-factor replacement therapies (e.g., emicizumab) and treatment of bleeds or coverage of surgeries/invasive procedure. Recently a haemophilia centre capacity building program was launched in China to further develop the infrastructure and support needed to improve the diagnosis of haemophilia, detection of inhibitors, and continue to improve the care of patients with haemophilia and inhibitors.

First experience of a hemophilia monitoring platform: florio HAEMO.

Background: florio HAEMO is a new hemophilia treatment monitoring application consisting of a patient smartphone application (app) and a web-based dashboard for healthcare professionals, providing several novel features, including activity tracking, wearable connectivity, kids and caregiver mode, and real-time pharmacokinetic factor level estimation. Objectives: To assess intuitiveness, ease-of-use, and patient preference of florio HAEMO in Central Europe using a cross-sectional survey. Methods: This survey was conducted in six Central European countries between 9 December 2020 and 24 May 2021. The online questionnaire included 17 questions about overall satisfaction, ease-of-use, intuitiveness, and patient preference. Adults or children with hemophilia on regular prophylaxis and using the florio HAEMO app for a minimum of 1 week were invited to complete the online questionnaire by their treating physician. Results: Sixty-six participants took part in the survey. The median duration for all respondents using the florio HAEMO app was 3 to 4 weeks. Overall, 89.4% of users reported being very satisfied or rather satisfied after using florio HAEMO. Of the 23 respondents who had switched from another hemophilia app, 87.0% indicated that they strongly preferred or preferred using florio HAEMO. Most florio HAEMO users reported that the app was very easy or rather easy to use (97.0%) and intuitive (94.0%). florio HAEMO had a positive impact on daily living, with 78.8% of users reporting that the app was very important or rather important to them. Conclusions: This survey suggests that florio HAEMO is an easy-to-use and intuitive app to assist self-management of home prophylaxis.

Zero incidence of factor VIII inhibitors and successful haemostatic response in previously factor VIII-treated patients with haemophilia A switching to turoctocog alfa in a noninterventional study.

INTRODUCTION: Turoctocog alfa (NovoEight® ) is a B-domain-truncated recombinant factor VIII (FVIII) approved for patients with haemophilia A. AIM: To investigate the long-term safety and efficacy of turoctocog alfa in routine clinical practice. METHODS: Guardian 5 was a prospective, multinational, non-interventional, post-authorisation safety study. Male previously treated patients (> 150 exposure days [EDs]) of any age with severe/moderately severe haemophilia A (FVIII ≤ 2%) and a negative inhibitor test prior to first dosing (independent of FVIII-inhibitor history) were included to receive prophylaxis or on-demand treatment. The primary endpoint was the proportion of patients developing FVIII inhibitors (≥.6 Bethesda Units [BU]) after baseline visit, measured as per routine practice of each study site during clinic visits. Secondary endpoints included haemostatic effect, annualised bleeding rate (ABR), and adverse reactions assessment. The study concluded when 50 patients reached 100 EDs/patient minimum. RESULTS: Seventy patients were screened and 68 exposed to turoctocog alfa; 63 (92.6%) were on prophylaxis and five received on-demand treatment. Six (8.8%) patients reported a history of positive inhibitors. During the study, patients were exposed to turoctocog alfa for a mean (standard deviation) of 131.9 (99.0) days/patient. Fifty-five of 58 patients who completed the study were tested for FVIII inhibitors; no positive tests were reported. Overall success rate of turoctocog alfa for treatment of bleeds was 87.3%. Among patients receiving prophylaxis, median (range) ABR was 1.97 (.0-25.5) bleeds/year; estimated ABR (negative binomial model) was 3.65 (95% confidence interval: 2.53-5.25). CONCLUSION: Turoctocog alfa was safe and efficacious for haemophilia A treatment in routine clinical practice.

Recombinant porcine factor VIII: Lessons from the past and place in the management of hemophilia A with inhibitors in 2021.

The most serious complication of factor VIII (FVIII) replacement therapy is the occurrence of anti-FVIII alloantibodies that can strongly reduce or abolish the effect of human FVIII products. Bypassing agents to control bleeding episodes are recommended for these patients, but their efficacy is difficult to predict and monitor. FVIII products derived from porcine plasma had an important role in the treatment of hemophilia A for 50 years, from 1954 to 2004. Indeed, porcine FVIII could achieve hemostasis in patients in whom human FVIII products were ineffective. A recombinant porcine FVIII product is now available. This highly purified protein has the same biochemical and hemostatic properties, but much lower risks of infection and toxicity compared with plasma-derived porcine FVIII. The product is licensed in the United States and Europe for the treatment of acquired hemophilia A. However, this recombinant molecule could also be of clinical interest for people with inherited hemophilia A and inhibitors, particularly for the management of bleeding episodes in people receiving emicizumab as prophylactic treatment in the absence of anti-porcine FVIII antibodies.

Design of an international investigator-initiated study on MOdern Treatment of Inhibitor-positiVe pATiEnts with haemophilia A (MOTIVATE).

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.

Optimizing the management of patients with haemophilia A and inhibitors in the era of emicizumab: Recommendations from a German expert panel.

Standard treatment of haemophilia A is based on replacing the missing coagulation factor VIII (FVIII) to treat and prevent bleeding episodes. The most challenging complication of FVIII therapy is the development of neutralizing antibodies (inhibitors) that can render treatment ineffective. Eradication of the inhibitor through immune tolerance induction (ITI) remains the most effective strategy for managing these patients. Bypassing agents can be used to help restore haemostasis in inhibitor patients. Several novel agents have recently been developed, such as the FVIII mimetic agent emicizumab, which has been effective in reducing the annualized bleeding rate in haemophilia A patients with inhibitors. When coadministered with repetitive high doses of activated prothrombin complex concentrate (ie >100 U/kg/d for ≥24 hours), emicizumab was associated with thrombotic microangiopathy and thrombosis events. As a consequence the United Kingdom Haemophilia Centres Doctors' Organisation (UKHCDO) issued the first guidance on the treatment of bleeding episodes in patients receiving emicizumab. To build on and extend this work, a panel of German haemophilia specialists met to discuss the UK guidance, review current evidence and provide additional guidance for German healthcare professionals on how to optimize the management of patients with haemophilia A receiving emicizumab. Recommendations are provided on the use of bypassing and other agents to manage breakthrough bleeding, ITI in the emicizumab era, haemostatic support during surgery and issues relating to laboratory monitoring.

Practical Guidance of the GTH Haemophilia Board on the Use of Emicizumab in Patients with Haemophilia A.

Emicizumab has been approved for bleeding prophylaxis in patients with haemophilia A (PWHAs) with or without inhibitors. Because of substantial differences between factor VIII (FVIII) and Emicizumab, the 'Ständige Kommission Hämophilie' of the German, Austrian, Swiss Society for Thrombosis and Haemostasis Research (GTH) established a practical guidance for the use of Emicizumab in PWHAs. A systematic literature research was conducted in PubMed. Based on this and on personal experience, this practical guidance has been developed. Each single statement has been discussed among members of the 'Ständige Kommission Hämophilie' and revised accordingly. The final set of recommendations has been approved by all authors analogous to the Delphi method. This practical guidance is provided for physicians treating PWHAs with regard to general aspects, patient education, bleeding treatment, surgery, use of Emicizumab in previously untreated patients (PUPs), patients with newly diagnosed inhibitors and elderly patients. Patients should be treated in expert centres and adequate laboratory tests to monitor Emicizumab levels, FVIII replacement and inhibitors should be available. Early experience of immune tolerance induction protocols integrating Emicizumab is reviewed, and the limited experience in PUPs and very young children is described. So far, no thromboembolic complications have been reported with the concomitant use of FVIII or recombinant activated FVII for bleeding treatment or surgery. Activated prothrombin complex concentrate doses of >100 U/kg for >24 hours should be avoided whenever possible because of the high risk of thrombosis and/or thrombotic microangiopathy. In conclusion, this study is designed to support haemophilia physicians using Emicizumab in physicians treating hemophilia and using (PWHAs). With further post-marketing experience and trials, regular updates are necessary.

Favorable pharmacokinetics in hemophilia B for nonacog beta pegol versus recombinant factor IX-Fc fusion protein: A randomized trial.

BACKGROUND AND OBJECTIVE: Nonacog beta pegol (N9-GP) and recombinant factor IX-Fc fusion protein (rFIXFc) are extended half-life rFIX compounds. We report the first single-dose pharmacokinetic trial of N9-GP and rFIXFc. PATIENTS/METHODS: Paradigm 7 was a multicenter, open-label, randomized, crossover trial in previously treated (>150 exposure days) adults with congenital hemophilia B (FIX activity ≤2%). Patients received single intravenous injections (50 IU/kg) of N9-GP and rFIXFc with at least 21 days between doses. Plasma FIX activity, predose, and at serial time points up to 240 hours postdose, was measured using validated one-stage clotting assays (SynthAFax for N9-GP; Actin FSL for rFIXFc) and a chromogenic assay (ROX factor IX) with normal human plasma as calibrator. The primary endpoint was area under the FIX activity-time curve from 0 to infinity, dose-normalized to 50 IU/kg (AUC0-inf,norm). RESULTS: Fifteen patients received study treatment. Based on FIX activity results from the one-stage clotting assays, estimated AUC0-inf,norm was significantly greater for N9-GP than rFIXFc (ratio: 4.39; P < 0.0001, based on a two-sided test on 5% significance level). In addition, N9-GP had a longer terminal half-life, two times higher incremental recovery at 30 minutes and maximum FIX activity (dose-normalized to 50 IU/kg) and six times higher FIX activity at 168 hours than rFIXFc. These findings were largely comparable with the chromogenic assay data and are consistent with published data for each compound. CONCLUSIONS: In this comparison, N9-GP demonstrated favorable pharmacokinetic characteristics versus rFIXFc, helping clinicians to understand differences between N9-GP and rFIXFc. REGISTRATION: This trial is registered with clinicaltrials.gov (NCT03075670) and the European Clinical Trials Database (EudraCT: 2016-001149-25).

The changing face of immune tolerance induction in haemophilia A with the advent of emicizumab.

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.

Inhibitors: A Need for Eradication?

The development of inhibitors against factor VIII (FVIII) concentrates represents a significant treatment complication for hemophilia. Immune tolerance induction (ITI) therapy eradicates inhibitors in 60-80% of patients, resulting in a normal FVIII response. This article, based on presentations at the 6th International Coagulation Meeting, held in Barcelona, Spain, in September 2017, provides an overview of management approaches for patients with inhibitors and briefly tabulates four cases of ITI therapy (first-line or rescue ITI therapy in pediatric and adult patients) with successful outcomes. Switching FVIII product from recombinant FVIII to plasma-derived FVIII/VWF concentrate may be helpful in eradicating inhibitors. The rate of decline of inhibitor titer in the initial stages of ITI therapy is a good indicator of the success or failure of therapy, although prognostic biomarkers are needed. The development of the bispecific monoclonal antibody emicizumab, which was recently shown to reduce bleeding in inhibitor patients, offers a potential alternative therapeutic option. However, the benefits of inhibitor eradication, including a wider choice of cheaper therapeutic products for preventing and treating bleeds, suggest that at least one attempt of ITI therapy should be offered to patients who develop inhibitors.

Population Pharmacokinetic Modeling Of On-Demand And Surgical Use Of Nonacog Beta Pegol (N9-GP) And rFIXFc Based Upon The paradigm 7 Comparative Pharmacokinetic Study.

AIM/OBJECTIVE: Understanding pharmacokinetic (PK) differences between standard and extended half-life (EHL) products is important, particularly for factor IX (FIX), where differences are more significant than for factor VIII. Two single-dose PK trials showed N9-GP achieves higher FIX levels and greater area-under-the-curve than pdFIX, rFIX, and rFIXFc through higher recovery and longer terminal half-life. In paradigm 7, N9-GP demonstrated consistently favorable PK characteristics compared with rFIXFc. Collins et al explored population PK differences between N9-GP and pdFIX/rFIX based upon paradigm 1 data. This analysis uses population PK models based upon the paradigm 7 trial. METHODS: 15 patients (21-65 years) with hemophilia B received single 50-IU/kg doses of N9-GP and rFIXFc ≥21 days apart. A population PK model developed from single-dose PK profiles simulated plasma FIX activity following dosing for surgery and on-demand treatment of bleeds. Simulations explored doses and frequencies required to sustain target World Federation of Hemophilia (WFH) factor activity levels. RESULTS: PK profiles of N9-GP and rFIXFc were described by one- and three-compartment models, respectively. Simulations predicted significantly reduced dosing frequency and consumption for N9-GP than rFIXFc. For severe bleeds, a single N9-GP dose (80 IU/kg) is sufficient to maintain WFH-recommended FIX levels, whereas multiple rFIXFc doses are required. For surgery, redosing in the first week with N9-GP is modeled at day 6 vs rFIXFc dosing at 6, 30, 54, 78, and 126 hrs. For life-threatening bleeds, N9-GP is required at days 0, 3, 6, 13, and 18 vs rFIXFc redosing after 6 hrs with 10 additional doses at 24-, 48-, and 72 hr intervals. CONCLUSION: PK modeling approaches based upon direct comparative studies offer insights into PK differences between EHL FIX products. Model simulations show N9-GP may allow on-demand treatment and perioperative management with 55-75% fewer injections and 65-74% lower overall factor concentrate consumption than rFIXFc.

The importance of inhibitor eradication in clinically complicated hemophilia A patients.

INTRODUCTION: Inhibitors against factor VIII (FVIII), which develop in around 20-30% of patients with severe hemophilia A, represent a significant complication of on-demand or prophylactic FVIII therapy. Currently, the main treatment option for inhibitor patients is eradication using immune tolerance induction (ITI) therapy. Areas covered: This article reviews inhibitor eradication in clinically complicated hemophilia A patients. The benefits and disadvantages of ITI therapy are discussed, with reference to the new nonfactor replacement agents such as emicizumab, which are becoming available. Expert commentary: At present, ITI therapy is the method of choice for all inhibitor patients, but as alternative treatment options become increasingly available, this may change in the future. Despite the development of nonfactor replacement agents, ITI therapy is likely to maintain a key role in the management of inhibitor patients, although changes in ITI therapy regimens including the timing of ITI initiation, the dosing regimen, the management of thrombotic risk or safety, laboratory assessment of ITI outcomes, and maintenance treatment after ITI success, may be necessary.

Risk Factors for the Progression from Low to High Titres in 260 Children with Severe Haemophilia A and Newly Developed Inhibitors.

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]: 1.0­6.5), family history of inhibitors (OR: 7.2; 95% CI: 1.8­28.4) and the use of high-dose immune tolerance induction, defined as ≥100 IU FVIII concentrate/kg/d (OR: 3.9; 95% CI: 1.5­10.0). These results suggest that high-dose immune tolerance induction should be avoided as the initial strategy in patients who develop low-titre FVIII inhibitors.

Challenges of the management of severe hemophilia A with inhibitors: two case reports emphasizing the potential interest of a high-purity human Factor VIII/von Willebrand factor concentrate and individually tailored prophylaxis guided by thrombin-generation test.

Severe hemophilia A is an X-linked bleeding disorder. Immune tolerance induction (ITI) is the best strategy of treatment when patients develop inhibitors. The objective is to illustrate the benefit of a high-purity human factor VIII/von Willebrand factor (VWF) concentrate (Octanate) in the management of ITI. We also wanted to raise the potential interest of laboratory assays such as thrombin-generation test (TGT) and epitope mapping. Two patients were treated during ITI, first with a recombinant FVIII and then with plasma-derived factor VIII without success, and, finally, with Octanate. Bypassing agents were used based on the results of TGT. Epitope mapping was performed during ITI therapy. These observations suggest the potential contribution of Octanate in the management of ITI in difficult cases. The use of bypassing agents can be necessary in prophylaxis or to treat bleedings, and may be guided by TGT results. Epitope mapping is used to describe the inhibitor. This article shows a decrease of the inhibitor directed against the C2 domain after initiation of Octanate. A high-purity human factor VIII/von Willebrand factor concentrate (Octanate) may be a valuable therapeutical option for ITI therapy. TGT and epitope mapping could be of help in the management of ITI.

Type and intensity of FVIII exposure on inhibitor development in PUPs with haemophilia A. A patient-level meta-analysis.

The impact of treatment-related factors on inhibitor development in previously untreated patients (PUPs) with haemophilia A is still debated. We present the results of a collaborative, individual patient data meta-analytic project. Eligible data sources were published cohorts of PUPs for which patient-level data were available. The exposures of interest were factor (F)VIII type (recombinant [rFVIII] vs plasma-derived [pdFVIII]) and treatment intensity (≥ vs < 150 IU/kg/week) at first treatment. Family history of inhibitors, F8 mutations, age, treatment regimen (on-demand vs prophylaxis), secular trend and surgery were analysed as putative confounders using different statistical approaches (multivariable Cox regression, propensity score analyses, CART). Analyses accounted for the multi-centre origin of the data. We included 761 consecutive, unselected PUPs with moderate to severe haemophilia A from 10 centres in Egypt, Germany, Israel and Italy. A total of 27 % of patients developed inhibitors; 40 % and 22 % of patients treated with rFVIII and pdFVIII (unadjusted HR 2.2, 95 % CI 1.6-2.9), respectively; 51 % and 24 % of patients receiving high- and low-intensity treatment (unadjusted HR 2.9, 95 % CI 2.0-4.2), respectively. In adjusted analyses, only treatment intensity remained an independent predictor; the effect of FVIII type was largely due to confounding, but with a significant interaction between FVIII type and treatment intensity. This patient-level meta-analysis confirms, across different statistical approaches, that high-intensity treatment is a strong risk factor for inhibitor development. The possible role of FVIII type in subgroups is suggested by the test for interactions but could not be proven because of the limited subgroups sample sizes.