Risk factors for inhibitor development in severe hemophilia A

Elevated memory T-cell conversion in a preclinical mouse model of hemophilia A

One of the major challenges in the choice of the best therapeutic approach for the treatment of patients affected by hemophilia A (HA) is the definition of criteria predicting the formation of factor VIII (FVIII) neutralizing antibodies, called inhibitors. Both genetic and environmental elements influencing the immune response toward FVIII have been identified but still not all the factors causing the pathological rejection of FVIII have been identified. Since there is a connection between coagulation and inflammation, here we assessed the role played by the FVIII deficiency in shaping the humoral and cellular response toward an antigen other than FVIII itself. To this aim, we challenged both HA and wild-type (WT) mice with either FVIII or ovalbumin (OVA) and followed antigen-specific antibody level, immune cell population frequency and phenotype up to 9 weeks after the last antigen booster. The activation threshold was evaluated in vitro by stimulating the murine T cells with a decreasing dose of α-CD3. The humoral response to FVIII was similar between the two groups while both the in vivo and in vitro experiments highlighted an antigen-independent sensitivity of HA compared with WT T cells causing an increase in memory T-cell conversion and proliferation capability.

Prediction of inhibitor development in previously untreated and minimally treated children with severe and moderately severe hemophilia A using a machine-learning network

BACKGROUND

Prediction of inhibitor development in patients with hemophilia A (HA) remains a challenge.

OBJECTIVES

To construct a predictive model for inhibitor development in HA using a network of clinical variables and biomarkers based on the individual similarity network.

METHODS

Previously untreated and minimally treated children with severe/moderately severe HA, participants of the HEMFIL Cohort Study, were followed up until reaching 75 exposure days (EDs) without inhibitor (INH-) or upon inhibitor development (INH+). Clinical data and biological samples were collected before the start of factor (F)VIII replacement (T0). A predictive model (HemfilNET) was built to compare the networks and potential global topological differences between INH- and INH+ at T0, considering the network robustness. For validation, the "leave-one-out" cross-validation technique was employed. Accuracy, precision, recall, and F1-score were used as evaluation metrics for the machine-learning model.

RESULTS

We included 95 children with HA (CHA), of whom 31 (33%) developed inhibitors. The algorithm, featuring 37 variables, identified distinct patterns of networks at T0 for INH+ and INH-. The accuracy of the model was 74.2% for CHA INH+ and 98.4% for INH-. By focusing the analysis on CHA with high-risk F8 mutations for inhibitor development, the accuracy in identifying CHA INH+ increased to 82.1%.

CONCLUSION

Our machine-learning algorithm demonstrated an overall accuracy of 90.5% for predicting inhibitor development in CHA, which further improved when restricting the analysis to CHA with a high-risk F8 genotype. However, our model requires validation in other cohorts. Yet, missing data for some variables hindered more precise predictions.

Simoctocog alfa (Nuwiq®) in children: early steps in life's journey for people with severe hemophilia A

People with severe hemophilia A usually experience their first bleed early in life. In children with severe hemophilia A, primary prophylaxis is recommended to prevent recurrent and potentially life-threatening bleeds that significantly impact day-to-day life. Factor VIII (FVIII) prophylaxis is well-established in children and has been shown to reduce the development of hemophilic arthropathy. However, a major challenge of FVIII therapy is the development of neutralizing anti-FVIII antibodies (FVIII inhibitors). Simoctocog alfa (Nuwiq®) is a human cell line-derived recombinant FVIII (rFVIII) whose immunogenicity, efficacy, and safety have been studied in 167 children with severe hemophilia A across two prospective clinical trials and their long-term extensions. In 105 previously untreated children, the inhibitor rate of 16.2% for high-titer inhibitors (26.7% for all inhibitors) was lower than published rates for hamster cell line-derived rFVIII products. There was no inhibitor development in previously untreated children with non-null F8 mutations and in previously treated children. In a case series of 10 inhibitor patients, 8 (80%) underwent successful immune tolerance induction with simoctocog alfa with a median time to undetectable inhibitor of 3.5 months. In an analysis of 96 children who enrolled in the extension studies and received long-term simoctocog alfa prophylaxis for up to 5 years, median spontaneous, joint, and total annualized bleeding rates were 0.3, 0.4, and 1.8, respectively. No thromboembolisms were reported in any of the 167 children, and there were no treatment-related deaths. Optimal care of children should consider several factors, including minimization of inhibitor development risk, maintaining tolerance to FVIII, highly effective bleed prevention and treatment, safety, and impact on long-term outcomes such as bone and joint health. In this context we review the pediatric clinical data and ongoing studies with simoctocog alfa.

High levels of anti-factor VIII immunoglobulin G4 and immunoglobulin G total are associated with immune tolerance induction failure in people with congenital hemophilia A and high-responding inhibitors

Background

Immune tolerance induction (ITI) is the treatment of choice to eradicate neutralizing anti-factor (F)VIII alloantibodies (inhibitors) in people with inherited hemophilia A. However, it is not successful in 10% to 40% of the cases. The biological mechanisms and biomarkers associated with ITI outcome are largely unknown.

Objectives

The aim of this study was to investigate the association of plasma cytokines (interferon-γ, tumor necrosis factor, interleukin [IL]-2, IL-4, IL-5, IL-6, IL-10, and IL-17A), chemokines (IL-8/CXCL8, RANTES/CCL5, MIG/CXCL9, MCP-1/CCL2, and IP-10/CXCL10), and anti-FVIII immunoglobulin (Ig) G total, IgG1, and IgG4 with ITI outcome.

Methods

In this cross-sectional analysis of the Brazilian Immune Tolerance Study, we assessed plasma levels of anti-FVIII IgGs using an enzyme-linked immunosorbent assay with plasma-derived FVIII and recombinant FVIII as target antigens, immobilized in microplates.

Results

We assayed 98 plasma samples of moderately severe and severe (FVIII activity, <2%) people with hemophilia A after completion of a first ITI course. Levels of anti-recombinant FVIII IgG total and IgG4 were higher in people with hemophilia A who failed ITI (IgG total optical density [OD], 0.37; IQR, 0.15-0.73; IgG4 OD, 2.19; IQR, 0.80-2.52) than in those who had partial (IgG total OD, 0.03; IQR, 0.00-0.14; IgG4 OD, 0.39; IQR, 0.09-1.11; P < .0001 for both) or complete success (IgG total OD, 0.04; IQR, 0.00-0.07; IgG4 OD, 0.07; IQR, 0.06-0.40; P < .0001 for both). Plasma cytokines, chemokines, and anti-FVIII IgG1 were not associated with ITI outcome.

Conclusion

Our results show that high levels of plasma anti-FVIII IgG4 and IgG total are associated with ITI failure.

Unearthing the genotype-inhibitor phenotype association in severe haemophilia A: A north Indian cohort study

INTRODUCTION

Various risk factors for inhibitor development in haemophilia A (HA) have been described but Indian data remains scanty.

AIM

We aimed to evaluate the genetic changes in Indian HA-patients that are associated with the development of inhibitors.

METHODS

All HA-patients with inhibitors who availed coagulation-laboratory services from January-2015 till December-2021 and had their samples preserved for DNA extraction were included in this study. An equal number of severity-matched HA patients without inhibitors were also included as controls. Intron 22 and intron 1 inversions in Factor VIII gene were identified using inverse-shifting-PCR. Inversion-negative patients were further assessed by targeted NGS, MLPA.

RESULTS

Thirty HA-patients with inhibitors were identified. All had severe-HA. Thirty severe-HA-patients without inhibitors were also included as controls. Intron 22 inversion (63.3%) and large deletions (15%) were the commonest variants identified. There was no difference in genetic variants in patients with low and high titre inhibitors. A3, A2 and C2 were the most common domains involved in inversion-negative patients with inhibitors. However, there was no significant difference in domain involvement among inversion-negative patients with and without inhibitors. Seven novel-variants were identified, including three large deletions, one large duplication and two nonsense variants in inhibitor-positive patients, and one frameshift variant in inhibitor-negative patient. After adjusting for clinical risk-factors, large deletions were independently associated with the presence of inhibitors [aOR:6.1 (1.41-56.3)].

CONCLUSION

Intron 22 inversions are the commonest variant in Indian patients with severe-HA. Large deletions predispose to inhibitor development independent of clinical risk factors.

Mutation detection and inhibitor analysis of 43 children with severe hemophilia A in a single center: three novel mutations

To investigate the risk factors of FVIII inhibitors development in severe hemophilia A (HA) patients who were received on-demand therapy and were infused with plasma cryoprecipitate and multiple FVIII concentrates alternately. We collected clinical information from 43 severe HA children who were treated with plasma cryoprecipitate and multiple FVIII concentrates. The F8 mutation was detected by long-distance PCR for inversion and detected by all exons and their flanking sequencing for other mutations. The inhibitor detection was performed by Nijmegen-modified Bethesda assay. The impact of novel amino substitutions on FVIII protein was predicted by SIFT and PolyPhen-2. The 3D analysis of missense mutations was performed using Swiss-PdbViewer. FVIII inhibitors were detected in nine cases (20.9%). All of the inhibitor positive cases had high risk F8 gene mutations. In most of the positive cases (7/9), inhibitors were developed during the first 10 EDs, which was significantly higher than that in the 10-50 EDs group and 50 EDs group (p = 0.009). Three novel mutations were reported, including c.214G > T (E72X), c.218 T > C (F73S), and c.2690C > G (S840X). For severe HA patients who are treated with multiple products of replacement therapy, it is important to supervise inhibitor during the first 10EDs, especially for those with high risk F8 gene mutations. F8 gene mutation is one of the most important genetic factors for inhibitor development. It is essential to detect F8 gene for all severe HA patients. Three novel mutations were reported to expand the mutation spectrum of the F8 gene.

Acquired Factor VIII Deficiency in Chronic Myeloid Leukemia: A Case Report

Factor VIII deficiency is mostly seen in hemophilia A, an X-linked recessive disorder. Patients would have a past medical history of bleeding diathesis or a family history of bleeding disorder. Acquired deficiencies of factor VIII are rare; some cases have been reported in solid malignancies. We present this case of acquired factor VIII deficiency in chronic myeloid leukemia (CML). A 72-year-old man was incidentally found to have leukocytosis at 31,000 and a platelet count of 3.2 million on a routine complete blood count (CBC). Prothrombin time (PT), international normalized ratio (INR), and partial thromboplastin time (PTT) showed an isolated elevation of PTT at 38.1 and a low factor VIII activity level at 39. The patient did not have any history or physical examination suggestive of bleeding diathesis. A bone marrow biopsy confirmed the BCR/ABL mutation, a diagnosis of CML was made, and the patient was started on dasatinib for one month. His PTT normalized after treatment for CML, suggesting a deficiency of factor VIII likely related to CML. The aim of this study is to highlight a case with acquired factor VIII deficiency due to CML and to emphasize the importance of coagulation workup in all newly diagnosed CML patients.

Large Intron Inversions in Romanian Patients with Hemophilia A-First Report

Background and Objectives: Despite the vast heterogeneity in the genetic defects causing hemophilia A (HA), large intron inversions represent a major cause of disease, accounting for almost half of the cases of severe HA worldwide. We investigated the intron 22 and intron 1 inversion status in a cohort of Romanian unrelated patients with severe HA. Moreover, we evaluated the role of these inversions as relative risk factors in inhibitor occurrence. Materials and Methods: Inverse shifting-a polymerase chain reaction method was used to detect the presence of intron 22 and intron 1 inversions in 156 Romanian patients with HA. Results: Intron inversion 22 was found in 41.7% of the patients, while intron 1 inversion was detected in 3.2% of the patients. Overall, large intron inversions represented the molecular defect in 44.9% of the studied patients. Our findings are in accord with previously published reports from Eastern Europe countries and with other international studies. The risk of inhibitor development was higher in patients with inversion 1 compared to the patients with HA without any inversion detected. Conclusions: The current study demonstrates the major causative role of large intron inversions in severe HA in Romanian patients. Moreover, our study confirms the contribution of intron 1 inversion in inhibitor development.

Factor VIII inhibitors in hemophilia A treated with emicizumab: longitudinal follow-up of outcomes

Background

Using emicizumab in lieu of immune tolerance induction (ITI) for patients with hemophilia A (HA) and factor (F)VIII inhibitors has been well described. However, decisions regarding ITI initiation, regimen, and preservation of tolerance remain to be elucidated.

Objectives

To study the course of FVIII inhibitors in patients with HA and a history of FVIII inhibitors receiving emicizumab prophylaxis.

Methods

Patients with HA, with and without FVIII inhibitors, initiating emicizumab prophylaxis were prospectively followed up in our center. All patients with current or previous inhibitors were included in this analysis. Plasma samples for FVIII inhibitor assays were obtained every 3 to 6 months or following FVIII exposure. Patients documented annual bleeding rate and any FVIII exposure days (EDs).

Results

Of 162 emicizumab-treated participants, 51 met the inclusion criteria. A decrease in annual bleeding rate was observed in all 51 participants followed up for a median of 3.3 years, with 31 breakthrough bleeding episodes reported in 22 of 51 participants. FVIII inhibitor level transiently increased following FVIII exposures in 5 of 15 failed ITI participants. Eight of 21 participants who did not undergo ITI were exposed to FVIII (1-2 EDs)), and 1 of these 8 participants demonstrated increased FVIII inhibitor levels after head trauma (following 1 ED). Among participants who underwent successful ITI, 8 of 15 patients were exposed to FVIII over a total of 13 EDs (1-2 ED(s) each) for traumatic breakthrough bleeds. In all these participants, inhibitor levels remained zero, indicating successful tolerance maintenance.

Conclusion

Our longitudinal follow-up of emicizumab-treated patients with HA and FVIII inhibitors shows that occasional exposure to FVIII may induce a transient anamnestic response. Nonetheless, no FVIII inhibitor recurrence was noted following FVIII exposures in patients who underwent successful ITI.

Early immune tolerance induction is a unique predictor of favorable outcomes in hemophilia A children with intron 22 inversion and high-responding inhibitors

BACKGROUND

The predictors of immune tolerance induction (ITI) outcomes in hemophilia A (HA) patients with the same F8 genetic background have not yet been evaluated, although the F8 genotype is strongly associated with ITI response. This study aims to explore the predictors of ITI outcomes in the same F8 genetic background by focusing on intron 22 inversion (Inv22) patients with high-responding inhibitors.

METHODS

HA children with Inv22 and high-responding inhibitors who received low-dose ITI therapy over 24 months were included in this study. ITI outcomes were centrally assessed at the 24th month of treatment. The predictive ability of clinical variables to identify ITI success was determined using the receiver operating characteristic (ROC) curve, and the predictor of ITI outcomes was analyzed on the multivariable Cox model.

RESULTS

Among the 32 patients investigated, 23 (71.9 %) achieved success. In univariate analysis, interval time from inhibitor diagnosis to ITI start (interval-time) was significantly associated with ITI success (P = 0.001); however, inhibitor titers showed no significance (P > 0.05). The interval-time demonstrated a good predictive value for ITI success with the area under the ROC curve of 0.855 (P = 0.002), and the cutoff value was 25.8 months (sensitivity, 87.0 %; specificity, 88.9 %). In the multivariable Cox model which considered success rate and time to success, interval-time was the only independent predictor (<25.8 months vs. ≥25.8 months, P = 0.002).

CONCLUSIONS

The interval-time was first identified as a unique predictor of ITI outcomes in HA patients with high-responding inhibitors under the same F8 genetic background (Inv22). An interval-time of <25.8 months was associated with increased ITI success and reduced time to success.

Design of a Real-World Observational Study in Previously Untreated and Minimally Treated Hemophilia A Patients: Protect-NOW

Background  The efficacy, safety, and immunogenicity of each of Octapharma's factor VIII (FVIII) products, Nuwiq, octanate, and wilate, have been investigated in previously untreated patients (PUPs) with severe hemophilia A in prospective clinical trials. The aim of the Protect-NOW study is to evaluate the effectiveness, safety, and utilization patterns of Nuwiq, octanate, and wilate in PUPs and minimally treated patients (MTPs; <5 exposure days [EDs] to FVIII concentrates or other blood products containing FVIII) with severe hemophilia A in a real-world setting. Real-world data provide valuable information that complement data obtained from interventional clinical trials. Methods  Protect-NOW (ClinicalTrials.gov identifier: NCT03695978; ISRCTN identifier: 11492145) is a real-world study in PUPs and MTPs treated with either the human cell line-derived recombinant FVIII Nuwiq (simoctocog alfa) or a plasma-derived FVIII concentrate containing von Willebrand factor (octanate or wilate). It is a prospective and (partly) retrospective, observational, international, noncontrolled, noninterventional study. A total of 140 PUPs and MTPs with severe hemophilia A will be enrolled across around 50 specialized centers worldwide and followed for either 100 EDs or a maximum period of 3 years from ED1. The primary objectives are to assess effectiveness in the prevention and treatment of bleeding episodes and overall safety, including inhibitor development. The secondary objectives are to assess utilization patterns (including dosage and frequency of administration) and the effectiveness in surgical prophylaxis. Conclusions  The Protect-NOW study will provide information on the treatment of PUPs and MTPs in routine clinical practice, which will help guide clinical decision making for treating these patients in the future.

Decline in health-related quality of life and foot and ankle patient reported outcomes measures in patients with haemophilia and ankle haemarthropathy

BACKGROUND

Haemophilia is an X-linked recessive genetic disorder characterised by bleeding within soft tissue and joints. The ankle is disproportionally affected by haemarthropathy when compared to the elbows and knees; reported as the most affected joints in patients with haemophilia. Despite advances in treatment, patients still report ongoing pain and disability, however, the impact has not been evaluated, nor has the effect on health-related quality of life (HRQoL) or foot and ankle patient-reported outcome measures (PROMs). The primary aim of this study was to establish the impact of ankle haemarthropathy in patients with severe and moderate haemophilia A and B. Secondly to identify the clinical outcomes associated with a decline in HRQoL and foot and ankle PROMs.

METHODS

A cross-sectional multi-centre questionnaire study was conducted across 18 haemophilia centres in England, Scotland and Wales with a recruitment target of 245 participants. The HAEMO-QoL-A and Manchester-Oxford Foot Questionnaire (MOXFQ) (foot and ankle) with total and domain scores measured impact on HRQOL and foot and ankle outcomes. Demographics, clinical characteristics, ankle haemophilia joint health scores, multi-joint haemarthropathy and Numerical Pain Rating Scales (NPRS) of "ankle pain over the past six months" were collected as a measure of chronic ankle pain.

RESULTS

A total of 243 of 250 participants provided complete data. HAEMO-QoL-A and MOXFQ (foot and ankle) total and index scores indicated worse HRQoL with total scores ranging from a mean of 35.3 to 35.8 (100 best-health) and 50.5 to 45.8 (0 best-health) respectively. NPRS (mean (SD)) ranged from 5.0 (2.6) to 5.5 (2.5), with median (IQR) ankle haemophilia joint health score of 4.5 (1 to 12.5) to 6.0 (3.0 to 10.0) indicating moderate to severe levels of ankle haemarthropathy. Ankle NPRS over six months and inhibitor status were associated with decline in outcome.

CONCLUSIONS

HRQoL and foot and ankle PROMs were poor in participants with moderate to severe levels of ankle haemarthropathy. Pain was a major driver for decline in HRQoL and foot and ankle PROMs and use of NPRS has the potential to predict worsening HRQoL and PROMs at the ankle and other affected joints.

Prophylaxis use of clotting factor replacement products in people with non-severe haemophilia: A review of the literature

INTRODUCTION

People with non-severe haemophilia appear to be under-treated in many countries, and this may lead to joint damage and worsen quality of life.

AIM

To review literature for clotting factor replacement prophylaxis in people with non-severe haemophilia A and B (HA/HB) in relation to long-term outcomes to support clinical decision-making.

METHODS

A targeted literature search was performed to identify studies published between 2000 and 2021 that included prophylaxis in people with non-severe HA/HB and long-term outcomes, including annualized bleeding rates, joint health and quality of life.

RESULTS

Although eligible articles included 2737 and 2272 people with mild or moderate HA, respectively, only 22% (n = 609) and 29% (n = 668) reported treatment regimens. A total of 549 people with moderate HA were treated with factor replacement prophylaxis and were from high-income countries. On the contrary, nearly all people with mild HA received desmopressin (n = 599). Details of treatment regimens for women with haemophilia and people with HB were sparse. Three studies provided long-term outcomes for people with moderate haemophilia who received prophylaxis with factor concentrate, supporting early prophylaxis in people with a frequent bleeding phenotype regardless of their endogenous clotting factor level to preserve joint health.

CONCLUSION

There remain large knowledge gaps when considering how to provide optimal treatment for people with non-severe haemophilia. Nonetheless, there is a strong rationale that prophylaxis should be considered early in life according to similar strategies as for severe haemophilia for those with a frequent severe bleeding phenotype.

FVIII inhibitor surveillance in children with hemophilia A in Indonesia: a report from the Indonesian Pediatric Hematology-Oncology Working Group

Background

Factor VIII (FVIII) inhibitor diagnosis and surveillance in Indonesia are challenging owing to geographic conditions and the lack of laboratory facilities nationwide for inhibitor assays. This study aimed to determine the prevalence of FVIII inhibitors in children diagnosed with hemophilia A (HA) in Indonesia.

Methods

A cross-sectional study was conducted in 12 hospitals in eight provinces of Indonesia between 2020 and 2021. Factor VIII inhibitor screening was performed in a central hemostasis laboratory for all children with HA (≤18 yr) who had received a minimum of 10 exposure days to clotting factor concentrates. The FVIII inhibitor titer was determined using the Bethesda assay.

Results

Children (388) were enrolled in this study, including 219 (56.4%), 131 (33.8%), and 38 (9.4%) with severe, moderate, and mild HA, respectively. The prevalence of children who developed FVIII inhibitors was 37 out of 388 (9.6%). Factor VIII inhibitors were found in 25/219 (11.4%) severe, 11/131 (8.3%) moderate, and 1/38 (2.6%) children with mild HA. Thirteen children had low-titer inhibitors and 24 had high-titer inhibitors, with a median of 9.44 (1.48‒412.0) Bethesda Units. Among 13 children with low-titer inhibitors, eight underwent a confirmation test, of which five tested negative and were classified as transient. A significant difference in annual joint bleeding rate was found between patients with low and high inhibitor titers and those without inhibitors (P＜0.001).

Conclusion

Factor VIII inhibitor prevalence in Indonesia was relatively low. However, the risk factors that may contribute to FVIII inhibitor development among Indonesian patients require further study.

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.

Low-dose immune tolerance induction in children with severe hemophilia A with high-titer inhibitors: Type of factor 8 mutation and outcomes

Background

No studies evaluated the role of F8 mutations in outcomes for low-dose immune tolerance induction (ITI) in people with severe hemophilia A (SHA) with high-titer inhibitors.

Objectives

To explore the association between F8 mutation types and low-dose ITI outcomes in children with SHA with high-titer inhibitors.

Methods

Children SHA with high-titer inhibitors who received low-dose ITI therapy at least for 1 year were included in this study. Based on the risk of inhibitor development, F8 mutations were classified into a high-risk group and a non-high-risk group. Rapid tolerance and the final ITI outcomes were assessed at the 12th and 24th month of treatment, respectively, and the predictor of outcomes was analyzed.

Results

Of 104 children included, 101 had F8 mutations identified. The children with non-high-risk mutations presented a higher rate of rapid tolerance than those with high-risk mutations (61.0% vs. 29.2%; p = 0.006). Among 72 children beyond 24 months of ITI, 55 children (76.4%) achieved success, 3 (4.2%) achieved partial success, and 14 (19.4%) failed. The children in the non-high-risk group showed a higher success rate (86.8% vs. 43.8%; p = 0.001) and a shorter time to success (mean time, 9.3 months vs. 13.2 months; p = 0.04) compared to those in the high-risk group. In multivariable logistic regression, F8 mutations were an independent predictor of ITI success (non-high-risk group vs. high-risk group, adjusted odds ratio [OR], 20.3; 95% confidence interval [CI], 3.5-117.8), as was the interval from inhibitor diagnosis to ITI start (adjusted OR, 0.95; 95% CI, 0.90-0.99). They remained the significant predictors when success time was taken into account in a Cox model.

Conclusions

Types of F8 mutation were a key predictor of outcomes for low-dose ITI in children with SHA with high-titer inhibitors. It can help to stratify the prognosis and guide clinical decisions.

Clinico-epidemiological and sociodemographic profile of patients with hemophilia in the Brazilian Amazon: High prevalence of hepatitis C infection and its possible corrrelation with inhibitor development

Hemophilia is a recessive genetic disease caused by a mutation on the X chromosome that has been linked to a high risk of transfusion-transmitted infections, especially sexually transmitted infections. The purpose of this retrospective study was to characterize the clinical and epidemiological profile and describe the prevalence of sexually transmitted viral infections in patients with hemophilia in the Northern Brazilian state of Amazonas. We assessed clinical, laboratory and sociodemographic data of hemophiliac patients (n = 311) for the period 2011-2019. The majority of the study population was composed of people with a low level of education aged 21-30 years old. The prevalence of HCV, HBV, and HTLV-1/2 infections among the study population were 10.52, 0.52, and 1.05%, respectively. No HIV infection was found among the patients. Between 2011 and 2015 the prevalence of HCV increased by over 100% and the incidence peaked in 2013. The severe hemophilia was associated with the presence of inhibitor factor (Odds Ratio [OD] 9.83; 95% IC: 3.41-27.62, p < 0.0001) or target joint (OD 6.59; 95% IC: 3.27-13.34, p < 0.0001). The presence of inhibitor was positive and significantly correlated with HCV infection (r = 1.00, p < 0.0001). Our results showed that HCV infection is highly prevalent in patients with hemophilia and might be involved in the development of inhibitors. Thus, these data provide new insights into the clinical and epidemiological profile of patients suffering from hemophilia in the Northern Brazilian state of Amazonas.

Case Report: A Child With Hemophilia A Serves as Donor for Hematopoietic Stem Cell Transplantation to Cure His Brother's Severe Aplastic Anemia

The first-line treatment of severe aplastic anemia is allogeneic hematopoietic stem cell transplantation with a matched sibling donor. However, co-morbidities of the identical donor can make donation difficult. We present a transplantation where in parallel with the patient's conditioning treatment, the preparation of the donor with severe hemophilia A required a special management with perioperative factor VIII substitution. Donation was successful without complications, and 18 months after transplantation, the patient and his donor are well without any long-term sequelae. To our knowledge, this is the first reported succesfull transplantation with hemophilic child serving as a bone marrow donor. The procedure did not mean a significant risk to donor health, so donors with hemophilia should not be excluded from donation.

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.

F8 gene mutation spectrum in severe hemophilia A with inhibitors: A large cohort data analysis from a single center in China

Introduction

Type of F8 gene mutation is the most important risk factor for inhibitor development in people with severe hemophilia A. However, there are few large cohort studies on the F8 mutation spectrum of people with severe hemophilia A with inhibitors.

Objective

This was the first large cohort study in children with severe hemophilia A with inhibitors from China that aimed to analyze the association between F8 variant types and inhibitor status.

Methods

The single‐center retrospective cohort study was conducted on children with severe hemophilia A with inhibitors admitted from January 2015 to December 2021. The clinical data were collected, and F8 genetic tests were performed.

Results

Among the 203 patients investigated, a mutation in F8 was identified in 196 cases. Most patients had deleterious mutations (153; 75.4%), including 82 cases of intron 22 inversions (40.4%); 40 cases of nonsense mutations (19.7%), with 15 cases in the light chain and 25 cases in the heavy chain; and 31 cases of large deletions or insertions (15.3%), with 29 cases involving more than one exon and 2 cases involving one exon. The large deletions or insertions encompassing multiple exons and nonsense mutations residing in the light chain were associated with not only the progression to a high‐titer inhibitor (P < .05) but also higher peak inhibitor titer (P < .05).

Conclusion

The F8 gene deleterious mutations, including intron 22 inversions, nonsense mutations, and large deletions or insertions, constitute the main mutation types in people with severe hemophilia A with inhibitors in China, with the latter mutation types (large deletions or insertions in multiple exons, and nonsense mutations in the light chain) signifying for a higher peak titer of inhibitor.

Risk Factors for Amputation in the Surgical Treatment of Hemophilic Osteoarthropathy: A 20-Year Single-Center Report

Purpose

Hemophilic osteoarthropathy (HO) is a common cause of spontaneous bleeding in hemophiliacs. Surgical procedures are necessary for patients with severe HO. As a last resort, amputation is sometimes needed to treat complex HO cases. This study aimed to review the existing records of patients who underwent amputations in HO surgical treatment, summarize the risk factors, and provide relevant references for surgeons.

Methods

We retrospectively reviewed the records of hemophilic patients received surgeries at Peking Union Medical College Hospital between 2000 and 2020. The amputation patients without neoplasm or acute trauma were screened out. Patient information was extracted from medical records. A literature retrieval of hemophilic amputation cases was conducted via PubMed. The risk factors of amputation were summarized and analyzed via descriptive statistics and Fisher's precision probability test.

Results

Four male hemophilia A patients out of 201 patients underwent lower limb amputation. The reasons of amputation contained severe pseudotumor with factor inhibitor and large bone defects, recurrent pathological fracture with pseudotumor, skin ulcer with chronic osteomyelitis, and pseudotumor with systematic infection. In cases reported in retrieved literature, severe pseudotumor with complications, bacterial infection and factor inhibitor were common factors. Discussion. As the first study on amputations in HO patients, we found that severe hemophilic pseudotumor, chronic bacterial infection, and coagulation factor inhibitor was potential risk factors for amputation. Sufficient factor replacement therapy is fundamental in the prevention of amputation. The early diagnosis and specially designed surgical techniques could improve the rate of limb salvage.

Genetic variants at the chromosomal region 2q21.3 underlying inhibitor development in patients with severe haemophilia A

Introduction

Inhibitor development affects about 30% of patients with severe haemophilia A (HA) and results from different environmental and genetic risk factors. Previously, we identified the missense variant rs3754689 in the LCT gene linked with this predisposition. Since rs3754689 variant is benign and is located in a conserved haplotype region, we hypothesized that the association signal captured by this variant is located in coinherited, neighbouring genes.

Aim

To identify novel genetic risk factors associated with inhibitor development in coding regions of R3HDM1, UBXN4, CXCR4, MCM6, DARS and miR128‐1 genes.

Methods

Targeted sequencing was performed in 246 severe HA patients (72 with and 174 without inhibitor): 181 previously and 65 newly enrolled.

Results

Forty‐one common and 152 rare variants passed the quality control. Logistic regression analysis of common variants identified rs3754689 and four additional variants (.011 < P < .047; FDR ranging .2‐.38). Logistic regression analysis performed only in the 220 Italian patients showed similar results (.004 < P < .05; FDR ranging .12‐.22). Three of these variants (rs3213892 and rs3816155 in the LCT intron 13 and rs961360 in the R3HDM1 intron10‐exon11 junction) may affect the expression of UBXN4 and R3HDM1, respectively. Rare variants did not show association with inhibitor development. Identified variants were not replicated in the multi‐ethnic SIPPET cohort of 230 severe HA patients.

Conclusion

Due to the limited sample size that may be responsible of the high FDR values, we could not confirm with certainty the analysed association. Further evaluation of the expression levels of analysed genes will confirm or not their role in inhibitor development.

Costs and management of patients with hemophilia A in France: the Hemraude study

OBJECTIVE

The Hemraude study was conducted to describe the profile of patients with HA, disease management, and economic burden in a collective perspective.

METHODS

This retrospective study was conducted using the French administrative healthcare claims database SNIIRAM/SNDS. Male patients treated for hemophilia A with a long-term illness (ALD) status or invalidity were included in the study between January 1, 2016 and December 31, 2017. Patients were classified in six treatment groups: no treatment, on-demand FVIII, prophylactic FVIII, FVIII in immune tolerance induction (ITI) protocol, on-demand bypassing agents, and prophylactic bypassing agents. Patients treated with FVIII in ITI protocol and those treated with bypassing agents are deemed to have developed inhibitors. HA patients were compared to a control population without coagulation disorder and matched (ratio 1:3) on age and sex.

RESULTS

A total of 4172 patients were included in the analysis, aged on average 35.2 years, 5.3% had HIV infection, and 8.8% had hepatitis B or C. In 2017, half of the patients received no treatment for HA, 46.7% were treated with FVIII (25% on demand, 20.6% with prophylaxis, and 1.1% ITI), 1.5% with bypassing agents. Patients treated with prophylactic treatments, either inhibitor or non-inhibitor, were less likely to be hospitalized for severe bleeding compared to patients receiving on-demand treatments. The average annual costs for HA management per patient were 72,209.60 €. The highest costs were observed in patients treated with FVIII in ITI protocol and those receiving prophylactic bypassing agents.

CONCLUSION

Direct costs of HA treatments for HA may be very high especially in the small percentage of patients developing inhibitors or treated with ITI protocol.

Total knee arthroplasty in hemophilia: lessons learned and projections of what's next for hemophilic knee joint health

INTRODUCTION

The purpose of this article has been to review the literature on total knee arthroplasty (TKA) in people with hemophilia (PWH), to mention the lessons we have learned from our own experience and to try to find out what the future of this type of surgery will be.

AREAS COVERED

A Cochrane Library and PubMed (MEDLINE) search of studies related to TKA PWH was analyzed. In PWH, the complication rate after TKA can be up to 31.5%. These include infection (7.1%) and bleeding in the form of hematoma, hemarthrosis or popliteal artery injury (8.9%). In a meta-analysis the revision arthroplasty rate was 6.3%. One-stage or two-stage revision arthroplasty due to infection (septic loosening) is not always successful despite providing correct treatment (both hematological and surgical). In fact, the risk of prosthetic re-infection is about 10%. It is necessary to perform a re-revision arthroplasty, which is a high-risk and technically difficult surgery that can sometimes end in knee arthrodesis or above-the-knee amputation of the limb.

EXPERT OPINION

TKA (both primary and revision) should be performed in centers specialized in orthopedic surgery and rehabilitation (knee) and hematology (hemophilia), and with optimal coordination between the medical team.

Hemophilia A Gene Therapy: Current and Next-Generation Approaches

INTRODUCTION

: Hemophilia comprises a group of X-linked hemorrhagic disorders that result from a deficiency of coagulation factors. The disorder affects mainly males and leads to chronic pain, joint deformity, reduced mobility, and increased mortality. Current therapies require frequent administration of replacement clotting factors, but the emergence of alloantibodies (inhibitors) diminishes their efficacy. New therapies are being developed to produce the deficient clotting factors and prevent the emergence of inhibitors.

AREAS COVERED

: This article provides an update on the characteristics and disease pathophysiology of hemophilia A, as well as current treatments, with a special focus on ongoing clinical trials related to gene replacement therapies.

EXPERT OPINION

: Gene replacement therapies provide safe, durable, and stable transgene expression while avoiding the challenges of clotting factor replacement therapies in patients with hemophilia. Improving the specificity of the viral construct and decreasing the therapeutic dose are critical toward minimizing cellular stress, induction of the unfolded protein response, and the resulting loss of protein production in liver cells. Next-generation gene therapies incorporating chimeric DNA sequences in the transgene can increase clotting factor synthesis and secretion, and advance the efficacy, safety, and durability of gene replacement therapy for hemophilia A as well as other blood clotting disorders.

Efficacy, safety, and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

Efficacy, safety, and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

Efficacy safety and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

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.

Efficacy, Safety and Pharmacokinetic Results of a Phase III, Open-Label, Multicenter Study with a Plasma-Derived Von Willebrand Factor (VWF)/Factor VIII (FVIII) Concentrate in Pediatric Patients <12 Years of Age with Hemophilia A (SWIFTLY-HA Study)

Background

Plasma-derived von Willebrand factor/factor VIII (pdVWF/FVIII; VONCENTO^®, CSL Behring) is a high-concentration, low-volume, high-purity concentrate, with a high level of VWF high-molecular-weight multimers and a VWF/FVIII ratio of ~2.4:1.

Methods

This study (NCT01229007) investigated the pharmacokinetics (PK), efficacy and safety of pdVWF/FVIII in 35 previously treated (minimum 20 exposure days [EDs]) pediatric patients (<12 years) with severe hemophilia A. PK was evaluated with a single 50 IU FVIII/kg dose of pdVWF/FVIII. Efficacy and safety analyses were performed during on-demand treatment (n=17) or prophylaxis (n=18) for up to 100 EDs with a maximum study duration of 12 months.

Results

PK profiles were similar for patients aged <6 years and those aged 6–12 years, and, as expected, the youngest patients had an increased clearance. On-demand patients reported 320 non-surgical bleeding (NSB) events and received a median number of 29.0 infusions (median dose 34.2 IU FVIII/kg). Hemostatic efficacy was assessed by the investigator as excellent/good in all cases (24%/76%). The 18 patients in the prophylaxis arm experienced 173 NSB events (97 NSBs [56%] in three patients). Five patients (28%) had no NSB events. Overall, patients received a median number of 92 infusions (median dose 30.6 IU FVIII/kg). The majority of bleeds (92%) were successfully controlled with only one infusion. Hemostatic efficacy was assessed by the investigator as excellent (86%) or good (14%). Inhibitors occurred in three patients of which two were transient (low titer) and one persisted (high titer). These three patients had known risk factors for inhibitor development.

Conclusion

This study demonstrated comparable PK profiles for pediatric patients aged <6 years and aged 6–12 years, and an excellent efficacy and safety profile in this population. The adverse events reported were mostly mild to moderate with inhibitor rates within the expected incidence range.

Performance of a clinical risk prediction model for inhibitor formation in severe haemophilia A

Background

There is a need to identify patients with haemophilia who have a very low or high risk of developing inhibitors. These patients could be candidates for personalized treatment strategies.

Aims

The aim of this study was to externally validate a previously published prediction model for inhibitor development and to develop a new prediction model that incorporates novel predictors.

Methods

The population consisted of 251 previously untreated or minimally treated patients with severe haemophilia A enrolled in the SIPPET study. The outcome was inhibitor formation. Model discrimination was measured using the C‐statistic, and model calibration was assessed with a calibration plot. The new model was internally validated using bootstrap resampling.

Results

Firstly, the previously published prediction model was validated. It consisted of three variables: family history of inhibitor development, F8 gene mutation and intensity of first treatment with factor VIII (FVIII). The C‐statistic was 0.53 (95% CI: 0.46–0.60), and calibration was limited. Furthermore, a new prediction model was developed that consisted of four predictors: F8 gene mutation, intensity of first treatment with FVIII, the presence of factor VIII non‐neutralizing antibodies before treatment initiation and lastly FVIII product type (recombinant vs. plasma‐derived). The C‐statistic was 0.66 (95 CI: 0.57–0.75), and calibration was moderate. Using a model cut‐off point of 10%, positive‐ and negative predictive values were 0.22 and 0.95, respectively.

Conclusion

Performance of all prediction models was limited. However, the new model with all predictors may be useful for identifying a small number of patients with a low risk of inhibitor formation.

Simoctocog Alfa (Nuwiq) in Previously Untreated Patients with Severe Haemophilia A: Final Results of the NuProtect Study

Introduction  FVIII inhibitor development is the most serious contemporary treatment complication in haemophilia A, particularly in previously untreated patients (PUPs). No inhibitors developed in clinical trials in previously treated patients treated with simoctocog alfa (Nuwiq), a fourth-generation recombinant FVIII produced in a human cell line.

Methods  The NuProtect study investigated the immunogenicity of simoctocog alfa in PUPs. NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. PUPs with severe haemophilia A (FVIII:C <1%) of any age and ethnicity were treated with simoctocog alfa for 100 exposure days or a maximum of 5 years. Patients were true PUPs without prior exposure to FVIII concentrates or blood components. Inhibitor titres were measured with the Nijmegen-modified Bethesda assay; cut-off for positivity was 0.6 BU mL ⁻¹ (≥0.6 to <5 low-titre, ≥5 high titre).

Results  A total of 108 PUPs with a median age at first treatment of 12.0 months (interquartile range: 8.0–23.5) were treated with simoctocog alfa. F8 mutation type was known for 102 patients (94.4%) of whom 90 (88.2%) had null F8 mutations and 12 (11.8%) had non-null mutations. Of 105 PUPs evaluable for inhibitor development, 28 (26.7%) developed inhibitors; 17 high titre (16.2%) and 11 low titre (10.5%). No PUPs with non-null F8 mutations developed inhibitors.

Conclusion  In the NuProtect study, the rate of inhibitor development in PUPs with severe haemophilia A treated with simoctocog alfa was lower than the rate reported for hamster-cell-derived recombinant factor VIII products in other recent clinical trials. No inhibitors were reported in PUPs with non-null F8 mutations.

Immune Responses to Plasma-Derived Versus Recombinant FVIII Products

The most severe side effect of hemophilia treatment is the inhibitor development occurring in 30% of patients, during the earliest stages of treatment with factor (F)VIII concentrates. These catastrophic immune responses rapidly inactivate the infused FVIII, rendering the treatment ineffective. This complication is associated with a substantial morbidity and mortality. The risk factors involved in the onset of the inhibitors are both genetic and environmental. The source of FVIII products, i.e. plasma-derived or recombinant FVIII products, is considered one of the most relevant factors for inhibitor development. Numerous studies in the literature report conflicting data on the different immunogenicity of the products. The SIPPET randomized trial showed an increased in the inhibitor rate in patients using recombinant FVIII products than those receiving plasma-derived products in the first exposure days. The SIPPET randomized trial showed an increase in the inhibitor rate in patients using recombinant FVIII products compared to those treated with plasma-derived products in the first days of exposure. The potential increase in the immunogenicity of recombinant products can be attributed to several factors such as: the different post-translational modification in different cell lines, the presence of protein aggregates, and the role played by the chaperon protein of FVIII, the von Willebrand factor, which modulates the uptake of FVIII by antigen presenting cells (APCs). Furthermore, the presence of non-neutralizing antibodies against FVIII has shown to be in increased inhibitor development as demonstrated in a sub-analysis of the SIPPET study. In addition, the presence of the specific subclasses of the immunoglobulins may also be an important biomarker to indicate whether the inhibitor will evolve into a persistent neutralizing antibody or a transient one that would disappear without any specific treatment. Recently, the availability of novel non-replacement therapies as well as emicizumab, administered by weekly subcutaneous infusion, have significantly changed the quality of life of patients with inhibitors showing a considerable reduction of the annual bleeding rate and in most patients the absence of bleeding. Although, these novel drugs improve patients' quality of life, they do not abolish the need to infuse FVIII during acute bleeding or surgery. Therefore, the issue of immunogenicity against FVIII still remains an important side effect of hemophilia treatment.

IgG subclasses as biomarkers for persistence of factor VIII inhibitors in previously untreated patients with severe haemophilia A

We investigated longitudinally the behaviour of anti-factor VIII (anti-FVIII) IgG subclasses for 6 months from inhibitor development in 43 patients from the Survey of Inhibitors in Plasma-Products Exposed Toddlers (SIPPET) trial who developed persistent or transient inhibitors. We first analysed 43 patients within 60 days post inhibitor detection. Then, 14 of these 43 patients were studied at five time points over 6 months. Our study showed that during the first 60 days, the risk of inhibitor persistence increased with the concomitant presence of an increasing number of IgG subclasses. Over the 6-month period post inhibitor detection, only the IgG2 subclass could be considered a hallmark of inhibitor persistence.

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

INTRODUCTION

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.

AIM

The purpose of this study is to evaluate the incremental cost-effectiveness ratio (ICER) of emicizumab versus BPAs.

METHODS

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.

RESULTS

Emicizumab treatment is dominant, ie lest costly and more effective, in the base-case analysis saving 234 191 € 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.

CONCLUSION

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.

Predicting the Development of Anti-Drug Antibodies against Recombinant alpha-Galactosidase A in Male Patients with Classical Fabry Disease

Fabry Disease (FD) is a rare, X-linked, lysosomal storage disease that mainly causes renal, cardiac and cerebral complications. Enzyme replacement therapy (ERT) with recombinant alpha-galactosidase A is available, but approximately 50% of male patients with classical FD develop inhibiting anti-drug antibodies (iADAs) that lead to reduced biochemical responses and an accelerated loss of renal function. Once immunization has occurred, iADAs tend to persist and tolerization is hard to achieve. Here we developed a pre-treatment prediction model for iADA development in FD using existing data from 120 classical male FD patients from three European centers, treated with ERT. We found that nonsense and frameshift mutations in the α-galactosidase A gene (p = 0.05), higher plasma lysoGb3 at baseline (p < 0.001) and agalsidase beta as first treatment (p = 0.006) were significantly associated with iADA development. Prediction performance of a Random Forest model, using multiple variables (AUC-ROC: 0.77) was compared to a logistic regression (LR) model using the three significantly associated variables (AUC-ROC: 0.77). The LR model can be used to determine iADA risk in individual FD patients prior to treatment initiation. This helps to determine in which patients adjusted treatment and/or immunomodulatory regimes may be considered to minimize iADA development risk.

Characterization of the von Willebrand factor/factor VIII complex produced by a novel purification process

Factor VIII (FVIII) is a blood coagulation protein that circulates as a complex with von Willebrand factor (vWF) in the plasma. In the survey of inhibitors in plasma product exposed toddlers (SIPPET) study, plasma-derived FVIII containing vWF was less immunogenic in hemophilia A patients than products with only high-purity FVIII only or recombinant FVIII. The  FVIII purified by the conventional purification process using anion-exchange (AEX) chromatography had a low vWF content. In this study, purified vWF was added to the purified FVIII to increase the vWF content. The purified vWF was recovered from the discarded washing solution of the AEX chromatography using cation-exchange (CEX) chromatography. The vWF/FVIII complex had an abundance of high molecular weight vWF similar to the normal plasma, and a low reactivity of FVIII inhibitors. Furthermore, its efficacy was observed in a mouse model of hemophilia A. Therefore, the vWF/FVIII complex produced by our new purification method could be an effective and less immunogenic therapeutic agent for the hemophilia A and von Willebrand disease.

Plasma levels of IL-1β and IL-37 in patients with severe haemophilia

Objective

Haemophilia A and B are disorders caused by the lack of clotting factors VIII and IX, respectively. Repeated bleeding into the same joint leads to haemophilic arthropathy (HA). Interleukin (IL)-1β is responsible for the pro-inflammatory response and IL-37 is induced by IL-1β stimuli to have an anti-inflammatory response and prevent uncontrolled inflammation and tissue damage. Our objective was to investigate plasma levels of IL-1β and IL-37 in patients with severe haemophilia with different severities of HA.

Methods

Peripheral blood samples were collected from 14 patients with severe haemophilia A and 6 with severe haemophilia B, and 18 healthy individuals. Plasma levels of IL-1β and IL-37 were detected by immunoassay, and severity of HA was evaluated using the Pettersson scoring system. Plasma levels of IL-1β and IL-37 were analysed in patients with severe haemophilia grouped by Pettersson score and in healthy individuals.

Results

Plasma levels of IL-1β and IL-37 were significantly higher in patients with severe haemophilia compared with healthy individuals and significantly lower in those with moderate to severe HA than in those with no or mild HA.

Conclusions

Plasma levels of IL-1β and IL-37 may be useful to track HA progression in patients with severe haemophilia.

Perioperative Management of Hemophilia A Patients Undergoing Cardiac Surgery: A Literature Review of Published Cases

OBJECTIVE

To investigate the perioperative management of patients with hemophilia A (HA) who undergo cardiac surgery.

DESIGN

Retrospective analysis of the published literature.

SETTING

University hospital.

PARTICIPANTS

HA patients undergoing cardiac surgery.

INTERVENTIONS

The PubMed, Embase, Web of Science Core Collection, CNKI, VIP, and WANFANG databases were searched with the terms "hemophilia A," "cardiac surgery," "cardiopulmonary bypass," "coronary artery bypass graft," "valve disease," and "congenital heart disease" to identify relevant articles. Data regarding patient characteristics, perioperative management protocols, and clinical outcomes were extracted and analyzed.

MEASUREMENTS AND MAIN RESULTS

Fifty articles, with 72 patients aging from 12 days to 80 years, were included. The analyzed population consisted of 36 (50%) mild HA, 10 (14%) moderate HA, and 25 (35%) severe HA patients. Factor VIII inhibitors were detected in 7 cases. Surgical procedures included 27 coronary artery bypass grafting procedures, 15 valve surgeries, 8 combined coronary artery bypass grafting with valve surgery procedures (1 with left ventricular assist device), 1 ventricular aneurysm resection with valve surgery, 11 corrections of congenital heart disease, 7 adult aortic surgeries, 3 heart transplantations, and 1 repair of heart injury. Factor VIII concentrates were used as a substitution therapy to ensure normalization of perioperative coagulation function. Although an uneventful clinical outcome was achieved in the majority of cases, 20% of patients developed complications with different severities.

CONCLUSIONS

Execution of a perioperative management strategy with a multidisciplinary approach, a thorough factor replacement protocol, and careful monitoring of factor levels facilitate an optimal outcome for HA patients undergoing cardiac surgery.

Maternal microchimerism protects hemophilia A patients from inhibitor development

Deleterious F8 mutations do not necessarily lead to the incidence of inhibitors in hemophilia A patients receiving replacement therapy. Maternal chimeric cells migrated into a fetus with hemophilia A during pregnancy could induce tolerance toward FVIII.

Translational Potential of Immune Tolerance Induction by AAV Liver-Directed Factor VIII Gene Therapy for Hemophilia A

Hemophilia A (HA) is an X-linked bleeding disorder due to deficiencies in coagulation factor VIII (FVIII). The major complication of current protein-based therapies is the development of neutralizing anti-FVIII antibodies, termed inhibitors, that block the hemostatic effect of therapeutic FVIII. Inhibitors develop in about 20-30% of people with severe HA, but the risk is dependent on the interaction between environmental and genetic factors, including the underlying F8 gene mutation. Recently, multiple clinical trials evaluating adeno-associated viral (AAV) vector liver-directed gene therapy for HA have reported promising results of therapeutically relevant to curative FVIII levels. The inclusion criteria for most trials prevented enrollment of subjects with a history of inhibitors. However, preclinical data from small and large animal models of HA with inhibitors suggests that liver-directed gene therapy can in fact eradicate pre-existing anti-FVIII antibodies, induce immune tolerance, and provide long-term therapeutic FVIII expression to prevent bleeding. Herein, we review the accumulating evidence that continuous uninterrupted expression of FVIII and other transgenes after liver-directed AAV gene therapy can bias the immune system toward immune tolerance induction, discuss the current understanding of the immunological mechanisms of this process, and outline questions that will need to be addressed to translate this strategy to clinical trials.

Prevalence of inhibitors and clinical characteristics in patients with haemophilia in a middle-income Latin American country

INTRODUCTION

Development of inhibitors is the most serious complication in patients with haemophilia (PWH). The prevalence of inhibitors in patients with severe haemophilia A (HA) is approximately 25%-30%. Inhibitor prevalence differs among populations. Some studies report a prevalence of almost twice in Hispanic as compared to Caucasian patients. Most data available, on the prevalence of inhibitors and their predisposing factors, originate from centres in developed countries.

AIM

Establish the prevalence of inhibitors of FVIII and FIX in Mexico.

METHODS

This was an observational, cross-sectional and descriptive study. The records of all patients diagnosed with haemophilia A (HA) or B (HB), with and without inhibitors, were included. Clinical and demographical characteristics of patients with inhibitors were assessed. Statistical analysis was performed using IBM SPSS version 22. The Ethics Committees of the various participating institutions approved this study.

RESULTS

A total of 1455 patients from the 20 participating centres were recruited, from which 1208 (83.02%) had HA and 247 (16.97%) were diagnosed with HB. The presence of inhibitors in severe HA was reported in 93/777(11.96%), and 10/162 (6.17%) in severe HB. Of them, 91.7% exhibited high titres in HA and 100% in HB.

CONCLUSION

In Mexico, the general prevalence of inhibitors varies considerably among centres. This study established a basis of comparison for future development and advances in the treatment and follow-up of patients. These findings also augment our understanding of risk factors related to inhibitor development.

Molecular insights into the mechanism of nonrecurrent F8 structural variants: Full breakpoint characterization and bioinformatics of DNA elements implicated in the upmost severe phenotype in hemophilia A

Hemophilia A (HA) provides excellent models to analyze genotype-phenotype relationships and mutational mechanisms. NhF8ld's breakpoints were characterized using case-specific DNA-tags, direct- or inverse-polymerase chain reaction amplification, and Sanger sequencing. DNA-break's stimulators (n = 46), interspersed repeats, non-B-DNA, and secondary structures were analyzed around breakpoints versus null hypotheses (E-values) based on computer simulations and base-frequency probabilities. Nine of 18 (50%) severe-HA patients with nhF8lds developed inhibitors, 1/8 affecting one exon and 8/10 (80%) affecting multi-exons. NhF8lds range: 2-165 kb. Five (45%) nhF8lds involve F8-extragenic regions including three affecting vicinal genes (SMIM9 and BRCC3) but none shows an extra-phenotype not related to severe-HA. The contingency analysis of recombinogenic motifs at nhF8ld breakpoints indicated a significant involvement of several DNA-break stimulator elements. Most nhF8ld's breakpoint junctions showed microhomologies (1-7 bp). Three (27%) nhF8lds show complexities at the breakpoints: an 8-bp inverted-insertion, and the remnant two, inverted- and direct-insertions (46-68 bp) supporting replicative models microhomology-mediated break-induced replication/Fork Stalling and Template Switching. The remnant eight (73%) nhF8lds may support nonhomologous end joining/microhomology-mediated end joining models. Our study suggests the involvement of the retroposition machinery (e.g., Jurka-targets, Alu-elements, long interspersed nuclear elements, long terminal repeats), microhomologies, and secondary structures at breakpoints playing significant roles in the origin of the upmost severe phenotype in HA.