Non-severe Haemophilia Research Articles

Population Pharmacokinetics of Clotting Factor Concentrates and Desmopressin in Hemophilia.

Hemophilia A and B are bleeding disorders caused by a deficiency of clotting factor VIII and IX, respectively. Patients with severe hemophilia (< 0.01 IU mL−1) and some patients with moderate hemophilia (0.01–0.05 IU mL−1) administer clotting factor concentrates prophylactically. Desmopressin (d-amino d-arginine vasopressin) can be applied in patients with non-severe hemophilia A. The aim of administration of factor concentrates or desmopressin is the prevention or cessation of bleeding. Despite weight-based dosing, it has been demonstrated that factor concentrates still exhibit considerable pharmacokinetic variability. Population pharmacokinetic analyses, in which this variability is quantified and explained, are increasingly performed in hemophilia research. These analyses can assist in the identification of important patient characteristics and can be applied to perform patient-tailored dosing. This review aims to present and discuss the population pharmacokinetic analyses that have been conducted to develop population pharmacokinetic models describing factor levels after administration of factor VIII or factor IX concentrates or d-amino d-arginine vasopressin. In total, 33 publications were retrieved from the literature. Two approaches were applied to perform population pharmacokinetic analyses, the standard two-stage approach and non-linear mixed-effect modeling. Using the standard two-stage approach, four population pharmacokinetic models were established describing factor VIII levels. In the remaining 29 analyses, the non-linear mixed-effect modeling approach was applied. NONMEM was the preferred software to establish population pharmacokinetic models. In total, 18 population pharmacokinetic analyses were conducted on the basis of data from a single product. From all available population pharmacokinetic analyses, 27 studies also included data from pediatric patients. In the majority of the population pharmacokinetic models, the population pharmacokinetic parameters were allometrically scaled using actual body weight. In this review, the available methods used for constructing the models, key features of these models, patient population characteristics, and established covariate relationships are described in detail.Electronic supplementary materialThe online version of this article (10.1007/s40262-020-00936-5) contains supplementary material, which is available to authorized users.

Non‐severe haemophilia: Is it benign? – Insights from the PROBE study

There are limited data on the impact of haemophilia on health status and health-related quality of life (HRQL) in people with non-severe (mild and moderate) haemophilia. To evaluate the health status of people living with mild or moderate haemophilia. Data on respondents with no bleeding disorder (NoBD), mild and moderate haemophilia patients were drawn from the PROBE study. Respondents were enrolled using network patient organizations. This analysis was performed as a cross-sectional study. Primary outcomes were reported bleeding, acute and chronic pain, activities of daily living and HRQL. A total of 862 respondents with NoBD (n=173), mild (n=102) and moderate (n=134) haemophilia were eligible, with a median age of 33, 42 and 43, respectively. In relation to haemophilia-related sequalae, 53% of male and 29% of female patients with mild and 83% of males with moderate haemophilia had more than 2-3 bleeds in the last 12months. Reporting of acute and chronic pain is less in those with NoBD compared to the mild and moderate cohorts for both genders. Multivariate analysis demonstrates significant reductions in quality of life using VAS, EQ-5D-5L and PROBE for males with mild and moderate haemophilia (P≤.001) with only PROBE indicating a significant reduction for females with mild (P=.002). People affected by mild or moderate haemophilia report a significant HRQL impact due to haemophilia-related bleeding. Future research is needed to identify the optimal care management of patients with mild and moderate haemophilia.

FVIII Immunogenicity-Bioinformatic Approaches to Evaluate Inhibitor Risk in Non-severe Hemophilia A.

The life-long inhibitor risk in non-severe hemophilia A has been an important clinical and research focus in recent years. Non-severe hemophilia A is most commonly caused by point mutation, missense F8 genotypes, of which over 500 variants are described. The immunogenic potential of just a single amino acid change within a complex 2,332 amino acid protein is an important reminder of the challenges of protein replacement therapies in diverse, global populations. Although some F8 genotypes have been identified as “high risk” mutations in non-severe hemophilia A (e.g., R593C), this is likely, in part at least, a reporting bias and oversimplification of the underlying immunological mechanism. Bioinformatic approaches offer a strategy to dissect the contribution of F8 genotype in the context of the wider HLA diversity through which antigenic peptides will necessarily be presented. Extensive modeling of all permutations of FVIII-derived fifteen-mer peptides straddling all reported F8 genotype positions demonstrate the likely heterogeneity of peptide binding affinity to different HLA II grooves. For the majority of F8 genotypes it is evident that inhibitor risk prediction is dependent on the combination of F8 genotype and available HLA II. Only a minority of FVIII-derived peptides are predicted to bind to all candidate HLA molecules. In silico predictions still over call the risk of inhibitor occurrence, suggestive of mechanisms of “protection” against clinically meaningful inhibitor events. The structural homology between FVIII and FV provides an attractive mechanism by which some F8 genotypes may be afforded co-incidental tolerance through homology of FV and FVIII primary amino sequence. In silico strategies enable the extension of this hypothesis to analyse the extent to which co-incidental cross-matching exists between FVIII-derived primary peptide sequences and any other protein in the entire human proteome and thus potential central tolerance. This review of complimentary in vitro, in silico, and clinical epidemiology data documents incremental insights into immunological mechanism of inhibitor occurrence in non-severe hemophilia A over the last decade. However, complex questions remain about antigenic processing and presentation to truly understand and predict an individual person with hemophilia risk of inhibitor occurrence.

Nonsevere hemophilia A: often overlooked, but not forgotten.

Nonsevere hemophilia A (NSHA) patients have received relatively little clinical and research attention as compared with their severe counterparts. There is increasing recognition that despite their milder bleeding phenotype, the management of NSHA can be a challenge, with most management decisions largely inferred from severe hemophilia A data. This review focuses on some of the more recent developments in the field of NSHA. Epidemiologic studies suggest that NSHA remain under-recognized and under-diagnosed globally. As the NSHA population ages, they are susceptible to age-related comorbidities. Large cohort studies of NSHA report that the most common primary cause of death is malignancy. NSHA patients have a lifetime risk of inhibitor development with increasing exposure to factor VIII concentrate. Even so, not all patients with inhibitors will require eradication treatment, irrespective of bleeding phenotype at time of inhibitor development. As there are currently no evidence-based strategies for inhibitor eradication in NSHA patients, preventive strategies are critical to mitigate inhibitor risk in NSHA. There is a need for active surveillance of NSHA patients by hemophilia treatment centers to address hemophilia-related issues and other age-related comorbidities, in collaboration with primary care physicians and other subspecialists.

4084 Predictors of mortality among non-severe hemophilia A patients in the United States

OBJECTIVES/GOALS: To determine predictors of mortality in non-severe hemophilia A (NSHA) patients. METHODS/STUDY POPULATION: The ATHNdataset was used to identify NSHA patients who have authorized the sharing of their demographic and clinical information for research. Factors examined included race, ethnicity, hemophilia severity, Hepatitis B, Hepatitis C and HIV infections. A mortality rate was calculated for each factors examined. The relative risk of death between patients in different categories of the factors was assessed by using the ratio of these mortality rates. To adjust for the effects of all of the studied factors with mortality, a multivariate analysis was performed using logistic regression. All hypothesis testing was two-tailed, with a significance level of .05. RESULTS/ANTICIPATED RESULTS: A total of 6,606 NSHA patients were followed for an average of 8.5 years. During 56,064 person years of observation, 136 (2.1%) NSHA patients died; 20% of deaths were malignancy-related. Mortality rates were similar across racial group. Hispanic patients were 60% less likely to die than non-Hispanic patients (p = 0.006). Patients with Hepatitis C infection and HIV infection were 7 times as likely to die compared to those without infections (p&lt;0.001). After adjusting for the effects of all examined factors in a multivariate analysis, patients with hepatitis C and HIV infection remain significantly associated with increased mortality at 6.1 times and 3.6 times the risk, respectively. DISCUSSION/SIGNIFICANCE OF IMPACT: Despite significant improvement in the therapeutic approaches for infectious diseases, Hepatitis C and HIV infections remain strong predictors of mortality in this NSHA cohort. CONFLICT OF INTEREST DESCRIPTION: N/A.

Discrepant Hemophilia A: An Underdiagnosed Disease Entity.

The term discrepant hemophilia A (DHA) denotes the discrepancy between factor VIII activity (FVIII:C) measured by different assay methodologies in patients with nonsevere hemophilia A (HA). The objective was to review the characteristics and the current understanding of mechanisms contributing to assay discrepancy in DHA. Characteristics of the DHA patients treated were examined by retrospective chart review. In addition, a literature review was performed to determine the current understanding of DHA. Three cases of DHA were diagnosed based on bleeding phenotype: 2 cases represented missed diagnoses of HA, and 1 represented misclassification of hemophilia severity. The revised diagnosis and classification of hemophilia directly affected clinical management. Review of the literature identified 18 articles with an estimated pooled prevalence of 36% (95% CI, 23%-56%; I2 = 85%; P < .01) among nonsevere HA. Furthermore, literature indicated that DHA is a feature of how different FVIII gene mutations affect FVIII:C activity within different assay methodologies. Our experience and literature review suggested that DHA is not only a laboratory phenomenon-it can affect clinical management in a subset of patients. A high index of suspicion for DHA is necessary while evaluating bleeding patients and/or classifying nonsevere HA.

Product type and the risk of inhibitor development in nonsevere haemophilia A patients: a case-control study.

SummaryInhibitor development is a major complication of treatment with factor VIII concentrates in nonsevere haemophilia A. It has been suggested that plasma‐derived factor VIII (FVIII) concentrates elicit fewer inhibitors than recombinant FVIII concentrates, but studies in severe haemophilia A patients have shown conflicting results. We designed a case‒control study to investigate the clinical and genetic risk factors for inhibitor development in nonsevere haemophilia A patients. We investigated whether the type of FVIII concentrate was associated with inhibitor development in nonsevere haemophilia A patients. This nested case‒control study includes 75 inhibitor patients and 223 controls, from a source population of the INSIGHT study, including all nonsevere haemophilia A patients (FVIII:C 2–40%) that were treated with FVIII concentrates in 33 European and one Australian centre. Cases and controls were matched for date of birth and cumulative number of exposure days (CED) to FVIII concentrate. A conditional logistic regression model was used to calculate unadjusted and adjusted odds ratios. No increased risk for inhibitor development was found for any type of FVIII concentrate; either when comparing recombinant FVIII concentrates to plasma‐derived FVIII concentrates (adjusted odds ratio 0·96, 95% confidence interval (CI) 0·36–2·52) or for specific types of FVIII concentrates.

Factor VIII Levels in Blood Group O and Non-O in Patients with Non-Severe Haemophilia a

Introduction ABO blood group affects levels of von Willebrand Factor (VWF) and Factor (F) VIII, as individuals with blood group non-O have higher levels of VWF and FVIII. To the best of our knowledge there is no data available regarding the association between blood group and FVIII in non-severe haemophilia. Aim We aimed to explore the influence of ABO blood group on VWF and FVIII levels in patients with non-severe haemophilia A (HA). Methods We recruited persons with non-severe HA (FVIII levels of 1-40%). Adult patients (age ≥ 18 years), with platelet count &gt; 105 /µl, without impaired renal and hepatic function, active cancer, surgery within the last 6 weeks, or overt infection within the last 2 weeks, who gave their informed consent were included. A blood sample was collected for laboratory analysis. The diagnosis of haemophilia was confirmed by molecular analysis of the FVIII gene in all patients. None of the patients had inhibitors against FVIII at the time of sample collection. The lowest FVIII level ever measured in each patient's history served as basis for the assessment of severity. Healthy male persons with a median age comparable to the patient group served as controls. We determined the following parameters: ABO blood group, FVIII, VWF activity (VWF:Act), and VWF antigen (VWF:Ag). FVIII was measured with a one-stage assay (Sysmex-CA7000 - Sysmex, Kobe, Japan, in multi-dilution mode with native FVIII-deficient plasma - Technoclone, Vienna, Austria and Aktin FS activator - Siemens, Marburg, Germany), VWF:Act (BC von Willebrand Reagent or Innovance VWF Ac - Siemens Healthcare, Marburg, Germany) and VWF:Ag levels with a latex agglutination assay (STA LIATEST VWF, Diagnostica Stago). Comparison of VWF and FVIII levels between blood group O and non-O was calculated with Mann-Whitney-U test, correlation between FVIII and VWF levels was calculated with Spearman's correlation, association of FVIII and VWF separated for blood group was calculated with univariable linear regression. Association of FVIII with VWF and blood group was calculated using multivariable linear regression. All calculations were performed with SPSS (IBM Version 25.0). Results A total of 89 persons with HA (71 with mild and 18 with moderate haemophilia) and 82 healthy controls were included. Patient characteristics are listed in Table 1. Median levels of VWF were significantly higher both in patients (p=0.002 for both VWF:Ag and VWF:Act) and healthy controls (p&lt;0.001 for both VWF:Ag and VWF:Act) with blood group non-O compared to individuals with blood group O. FVIII levels were not significantly different between blood group non-O and O in HA patients (15% vs. 14.1%, p=0.716) but significantly higher in healthy controls with blood group non-O versus O (150.0% vs. 109.5%, p&lt;0.001; Table 2). In HA there was no correlation between FVIII and VWF:Act (rho=0.180, p=0.095) or between FVIII and VWF:Ag (rho=0.028, p=0.795, Table 3). In univariable linear regression there was no significant association between VWF and FVIII in HA, neither in those with blood group non-O nor in those with blood group O (Figure 1). Also in multivariable linear regression there was no significant association between VWF (p=0.632) and blood group (p=0.929) with FVIII in patients with HA. In healthy controls, there was a strong positive correlation between FVIII and VWF:Act (rho=0.751, p&lt;0.001) and between FVIII and VWF:Ag (rho=0.790, p&lt;0.001) (Table 3). In the healthy controls with blood group non-O 1% elevation in the VWF:Ag was associated with 0.63% of elevation in the FVIII:Act and in blood group O 1% elevation in the VWF:Ag was associated with 0.66% of elevation in the FVIII:Act (Figure 2). Conclusions Neither the blood group nor the VWF had an influence on FVIII levels in non-severe HA patients. We conclude that the impact of the genetic mutation of the FVIII gene by far outweighs the influence of VWF levels and the blood group. Thus, for the diagnosis of HA and for determination of HA severity, the blood group needs not to be taken into account. Disclosures Pabinger: Roche: Honoraria; Sobi: Research Funding; Novo Nordisk: Research Funding; CSL Behring: Research Funding; Pfizer: Honoraria; Shire: Honoraria; Bayer: Honoraria; Sobi: Honoraria.

All-Cause and Inhibitor-Related Mortality in Non-Severe Hemophilia Α Patients in the United States

Introduction: The majority of published studies evaluating inhibitors have focused mainly on patients with severe hemophilia A. In non-severe hemophilia A (NSHA) patients, the development of inhibitors can have a profound clinical impact, with major bleeding complications similar to that of patients with severe or acquired hemophilia. Yet, epidemiological data on inhibitors in NSHA patients, specifically mortality, is scarce and currently limited to the European and Australian cohort [Eckhardt CL, et al. J Thromb Haemost. 2015 Jul;13(7):1217-251]. Objectives: To determine the all-cause and inhibitor-related mortality in NSHA patients in the United States using the ATHNdataset Methods: Subjects and study design The ATHNdataset is a 'limited dataset' as defined under the United States Health Insurance Portability and Accountability Act (HIPAA) to be free of protected health information, with data collection by more than 130 hemophilia treatment centers (HTC) across the United States. It includes patients with congenital bleeding disorders in the United States who have authorized the sharing of their demographic and clinical information for research. Data collection and definitions The ATHNdataset was queried on December 31, 2018 to extract the following information on NSHA patients: Patient demographics, inhibitor status, date of death, and primary cause of death. The presence of inhibitors was defined as: (i) ≥ 2 positive Bethesda inhibitor assay titers of ≥ 1.0 BU/mL; or (ii) a decrease in plasma FVIII coagulant activity (FVIII:C) to at least 50% of baseline activity and/or spontaneous bleeding symptoms in patients with inhibitor titers between 0.6 and 1.0 BU/mL. Patients who had a negative inhibitor history or have never been tested for FVIII inhibitors were classified as negative for inhibitors. Statistical analyses The person-year mortality rate was calculated as the ratio of the number of deaths to the number of person-years at risk, presented as rates per 1000 person-years. Person-years at risk was calculated for each patient as the time between the start of the observation period (January 1, 2010 or date of birth for patients who are born later) and the end of the observation period (date of death, loss-to follow-up or December 31, 2018). Patients who were deceased or lost to follow-up before January 1, 2010 were not included in the analysis. Inhibitor person-years at risk for inhibitor patients was calculated from January 1, 2010 if the first positive inhibitor test occurred prior to January 1, 2010 or from the date of the first positive inhibitor test that occurred during the observation period until the end of the observation period. Inhibitor-related death was attributed to all patients who had a positive inhibitor history. Mortality rates were compared between inhibitor and non-inhibitor patients using z- test. Results: Between 1/1/2010 and 12/31/2018, the ATHNdataset included 6,606 NSHA patients who were born between 1920 and 2018. Patients were observed for a total of 56,064 person-years. 85.57% (n = 5,653) of these patients were observed for the full nine years. The average follow-up time per patient was almost 8.5 years. Inhibitors developed in 171 (2.59%) NSHA patients. The median age for inhibitor development was 13 years (IQR, 6 - 37 years) and the mean age was 22 years. Demographics characteristics of the patients are listed in Table 1. All-cause mortality At the end of follow-up, there was a total of 136 deaths in the NSHA population, occurring at a median age of 63 years (IQR, 51 - 75 years). The overall all-cause mortality rate was 2.43 per 1,000 person-years (95% CI: 2.02 - 2.83). The most common primary cause of death was cancer (n=27, 19.9%) (Table 2). Inhibitor-related mortality Three deaths were associated with inhibitors. Inhibitor-related mortality rate was 2.40 per 1,000 person-years, whereas among the never inhibitor group, the mortality rate was 2.44 per 1,000 person-years (p = 0.790). Mortality risk ratio between inhibitor and never inhibitor was 0.98 (95% CI: 0.31 - 3.08). Conclusion: In NSHA patients, the development of inhibitors occurred at a relatively early age and was not associated with increased mortality. Disclosures Kempton: Novo Nordisk: Research Funding; Octapharma: Honoraria; Genentech: Honoraria; Spark Therapeutics: Honoraria. Key:Uniqure BV: Research Funding.

Validation of Instrument to Assess Hemophilia-Related Distress

Introduction: In chronic diseases such as diabetes and cancer, disease-related distress is known to impact disease management and health outcomes (Barry et al. J Health Psychol 2019). We sought to develop and validate an instrument to measure hemophilia-related distress (HRD). Methods: Using themes raised during qualitative interviews, questions were written to assess HRD. Questions were revised after review by clinicians and patient focus groups. The final formatted HRD instrument comprised 24 Likert scale questions (response level 0-5) plus a numerical rating of current distress on a 1-10 scale. The HRD total score is the sum of all domain scores and could range from 0-120 with lower scores indicating less HRD. Adults (≥18 years) with hemophilia receiving care at one of two hemophilia treatment centers were recruited to participate in the validation study. After informed consent, participants reported demographic and clinical information then completed the HRD instrument and questionnaires that measured characteristics similar to HRD including: the National Cancer Center Network (NCCN) Distress Thermometer, Kessler 6+ (K6), Patient Health Questionnaire (PHQ-9), Brief Pain Inventory (BPI), 5-level EuroQol-5D (EQ-5D-5L), Haem-A-Qol, Work Productivity and Activity Impairment Questionnaire plus Classroom Impairment (WPAI), and PROMIS-29. Analysis included factor analysis and assessment of internal consistency using Cronbach's α, construct validity using Pearson's correlation coefficient and discriminant validity by comparing subgroups of patients. A subset of participants electronically completed the HRD instrument a second time within 7 days of initial assessment. Test-retest reliability was assessed using an interclass correlation coefficient (ICC). Results: Among 130 enrolled participants, 126 completed the HRD instrument in a median time of 5.4 minutes (Q1;Q3 3.5;14.4) with overall HRD scores ranged from 2-83 (median=31.5). Subject characteristics are shown in table 1. Factor analysis of 1-5 domains was undertaken with final selection of a 4-domain instrument (RMSEA 0.057 [90% CI 0.041,0.072]; CFI 0.97). The 4 domains are (# of items, Cronbach's α): Hemophilia Management Concerns (7 items, 0.81); Financial Concerns (3 items, 0.81); Perceived Self-efficacy (3 items, 0.79); Daily Function Concerns (7 items, 0.85). Assessment of convergent validity (table 2) demonstrated a moderate correlation (&amp;gt;0.60) of the HRD total score with the NCCN Distress Thermometer, Haem-A-Qol total Score, and PROMIS social role domain. The HRD 0-10 scale correlated well with NCCN Distress Thermometer, PHQ-9 score, EQ-5D Index score, Haem-A-Qol total score, PROMIS anxiety, depression, and pain interference domains. Domain 4 (Daily Function Concerns) was well correlated with Haem-A-Qol total score as well as physical health and view of self domains, WPAI total activity impairment, and PROMIS pain interference. The HRD total score and domains 1-4 were mild to moderately correlated with the K6 measure of general psychological distress (0.3-0.54, p&amp;lt; 0.05). Distress was higher among those with less education than standard college or graduate degree (median score 36 vs. 23, p=0.018), not employed (median total score 42 vs 26, p=0.002), and disabled (median score 43 vs 30, p=0.010). The total score was not significantly different among those with severe hemophilia compared with non-severe disease. However, domain 1 (hemophilia management concerns) was higher among those with non-severe disease (median 9 vs 6, p=0.033). Test-retest reliability was assessed in 38 subjects. ICC values were 0.84 (95% CI 0.71-0.91) for the total score and 0.56 (95% CI, 0.30-0.75), 0.51 (95% CI 0.40-0.81), 0.67 (95% CI 0.45-0.81) and 0.72 (95% CI 0.53-0.85) for domains 1-4 respectively. Conclusions: The HRD instrument measures the subjective emotional state associated with chronic management of hemophilia. The instrument demonstrates good internal consistency, construct and discriminant validity, and retest-reliability with a low responder burden. Interestingly HRD was not greater among those with severe disease, which in combination with results from analysis of domain 1, may reflect greater unease and less mastery in managing their disease among adults with non-severe hemophilia. Future studies can explore how HRD is associated with disease management and outcomes and healthcare utilization. Disclosures Kempton: Novo Nordisk: Research Funding; Octapharma: Honoraria; Genentech: Honoraria; Spark Therapeutics: Honoraria. Buckner:Genentech: Consultancy; Spark Therapeutics: Consultancy; Shire: Consultancy; Kedrion: Consultancy; Pfizer: Consultancy; Novo Nordisk: Consultancy.

Long-Term Safety and Efficacy Data of a Plasma-Derived Factor VIII Concentrate with von Willebrand Factor for Treatment of Patients with Hemophilia A Covering 18 Years.

We describe the results of the (to our knowledge) longest long-term noninterventional study so far performed to obtain real-life data on the treatment of hemophilia A patients with a single plasma-derived FVIII concentrate containing von Willebrand factor (pdFVIII; Haemoctin/Faktor VIII SDH Intersero). A total of 198 patients (146 in Germany and 52 in Hungary), of whom 160 had severe and 38 nonsevere hemophilia A, representing all age groups (0-88 years; mean ∼25 years at inclusion) were analyzed during prophylactic or on-demand treatment over 18 years (overall 1,418 patient-years; mean >7 years). pdFVIII was very effective and well tolerated. The mean annual bleeding rate, including spontaneous and traumatic bleeds, was considerably lower for patients treated prophylactically (mean 5.4; median 3.1) than for patients treated on demand (mean 26.1; median 21.9). Inhibitors were found in 13% (3/23) and high-titer inhibitors in 4% (1/23) of previously untreated patients with severe hemophilia A. Four previously treated patients with severe hemophilia A developed inhibitors, thereof three high-titer inhibitors (3.3 and 2.5 high-titer inhibitors in 1,000 patient-years). No unexpected adverse effect on the health of the patients, no pdFVIII-related thrombosis, thromboembolic event, or hypersensitivity reaction, and no suspected viral transmission related to pdFVIII were documented.

Joint comorbidities among Swedish carriers of haemophilia: A register-based cohort study over 22years.

A significant fraction of women with an impaired factor VIII or IX gene in the X chromosome, carriers of haemophilia, will have clotting factor activities corresponding to those seen in males with non-severe haemophilia, hence, experience an increased bleeding tendency. Data describing the long-term joint outcomes among carriers are limited. We compared the age at onset, frequency of joint-related diagnoses as well as joint surgery and related hospitalizations among carriers of haemophilia with sex- and birthdate-matched controls from the general population. Carriers of haemophilia born 1941-2008 were identified through the haemophilia treatment centres' (HTCs) databases and the National Patient Register of Sweden. For each carrier, we included up to five individuals using the Swedish population register as comparisons. Data for the period 1987-2008 were obtained. Among 539 potential carriers identified, 213 had a known factor activity. Carriers with reduced factor activity and those with unknown factor activity had received their first joint-related diagnosis at a significantly earlier age than their comparisons. The same subgroups showed an overall 2.3- and 2.4-fold higher hazard for joint-related diagnoses compared with the general population. In addition, the hazards of joint-related outpatient hospitalization were 3.2-fold (95% CI: 1.2, 9.1) and 2.5-fold (95% CI: 1.6, 3.7). This was not observed for those with normal factor activity. Carriers of haemophilia suffer a significant risk for joint comorbidities. This risk seems to correlate to the factor activity. Our findings underline the importance of regular clinical follow-up of carriers at HTCs.

Desmopressin treatment combined with clotting factor VIII concentrates in patients with non-severe haemophilia A: protocol for a multicentre single-armed trial, the DAVID study

IntroductionHaemophilia A is an inherited bleeding disorder characterised by factor VIII (FVIII) deficiency. In patients with non-severe haemophilia A, surgery and bleeding are the main indications for treatment with FVIII...

In silico and in vitro evaluation of the impact of mutations in non-severe haemophilia A patients on assay discrepancies.

Haemophilia A (HA) is caused by a lack or reduced amount of factor VIII protein (FVIII). About one-third of patients with non-severe HA carrying specific missense mutations show discrepant results between FVIII activity (FVIII:C), measured by one-stage or chromogenic two-stage assays. The aim of this study was to elucidate the mechanism underlying the assay discrepancy in vitro and in silico. Thirteen missense mutations in the Factor 8-gene associated with discrepant results in patients were transiently expressed. FVIII:C of the mutations was determined using two one-stage assays (FVIII:C1st, FVIII:CBonn) and a two-stage chromogenic assay (FVIII:Cchr). Furthermore, thrombin generation test (TGT) and in silico analysis were performed to investigate the haemostatic potential as well as the structural impact of the variants, respectively. For the majority (9/13) of the analysed mutations, the discrepancy was confirmed. Moreover, we established a modified TGT protocol for in vitro characterization of FVIII. Hence, TGT parameters were significantly impaired in the group of variants associated with higher chromogenic values. Additionally, in silico analysis revealed the impact of the mutations on FVIII protein structure leading to assay discrepancy. Moreover, the data shows that also among one-stage clotting assays, assay discrepancy is observed. Our results show that for the majority of mutations, application of a global assay like TGT method could help to improve diagnosis or correct assessment of the severity of HA.

Thrombin Generation As a Promising Biomarker for the Prediction of Bleeding Phenotype in Patients with Non-Severe Hemophilia

Background: Non-severe hemophilia A and B account for 50% of patients with hemophilia, in which factor level does not consistently correlate with bleeding phenotype. Clinical decision-making in regards to timely prophylaxis initiation and tailored surgical management could be informed by a biomarker that is more predictive of bleeding phenotype. We hypothesized that a global method to assess clotting potential, such as thrombin generation (TG), is more predictive of bleeding phenotype than factor level.Objectives: Determine the ability of TG, as compared to standard baseline factor activity, to differentiate bleeding phenotype severity in patients with non-severe hemophilia.Methods: Subjects were recruited from two hemophilia treatment centers (HTCs): Rady Children's Hospital San Diego (RCHSD) and Center for Inherited Blood Disorders (CIBD). Subjects were eligible for enrollment if they were at least one year of age and had a diagnosis of non-severe congenital hemophilia A or B, or were genetically confirmed or suspected female carriers. All enrolled patients or their parents completed the standardized, self-administered pediatric bleeding questionnaire (Self-PBQ) or bleeding assessment tool (Self-BAT). Clinical and laboratory information were extracted from the medical chart, including age at diagnosis, bleeding event history, past surgical history, treatment history and factor VIII or IX gene analysis.Validation of self-reported bleeding symptoms was performed using chart-derived data. Bleeding phenotype was assessed using standard calculation of the bleeding score, as defined by the respective validated self-reported tools. For the purpose of this analysis, we defined a high bleeding score as 13 or more, while a low bleeding score was defined as 12 or less. After a washout period of 5x the standard half-life of the administered factor product, blood samples were collected at time of enrollment. Platelet poor plasma was obtained according to a strict protocol to minimize pre-analytical variables. TG was measured by means of the calibrated automated thrombogram, with three different reagents: low (1 pM of tissue factor [TF]), regular (5 pM of TF) and High (20 pM of TF). The following TG parameters were evaluated: Peak TG (Peak), estimated thrombin potential (ETP) and velocity index (VI).Results: Eighty-one subjects were enrolled. The median age of our cohort was 15.6 years (IQR 21.2, range 4.9 - 59.8), with a slight female predominance (51%) due to inclusion of female carriers. The median follow-up period at the HTC was 5.3 years (IQR 7.5 years), with the majority having follow-up for at least three years. Enrolled patients had the following diagnoses: mild hemophilia A (70%), mild hemophilia B (3%), moderate hemophilia A (13%), moderate hemophilia B (3%), hemophilia A carriers with normal factor VIII levels (10%) and hemophilia B carriers with normal factor IX levels (1%). Median age at diagnosis was 8 years (IQR 26.3, range 0.1 - 56.1), which strongly correlated lower baseline factor activity (r=0.573, p-value < 0.0001). The median baseline factor activity was 21% (IQR 26, range 2 - 249). Factor exposure occurred in 46% of patients (n=37), of which 5 patients were on prophylaxis at time of enrollment. Chronic arthropathy was present in 2 patients (one with mild hemophilia A and one with moderate hemophilia A) and none of the patients had a history of an inhibitor.The majority of patients had a low bleeding score (74% vs. 26%). Baseline factor level and TG values obtained with regular reagent (5 pM of TF) showed significant correlation with bleeding score (r = -0.229 to -0.237, p-value < 0.05), while values obtained with other reagents did not show a significant correlation. Sensitivity/specificity analysis revealed the following optimal cutoff values for differentiating between bleeding severities, as obtained from TG with regular reagent: ETP (<1240 nM min), Peak (<130 nM) and VI (<23 nM/min), with analysis results as shown in Table 1.Conclusion: Even though both TG and baseline factor level had comparable correlation with bleeding severity, all TG values with 5 pM TF showed a much higher sensitivity outcome and greater ability to differentiate between bleeding severities in this population. This approach shows potential for predicting bleeding severity in patients with non-severe hemophilia and should be validated in long-term prospective studies. [Display omitted] DisclosuresNossair:Novo Nordisk: Other: Conference - Haemophilia Acadamy; Novo Nordisk: Research Funding. Hwang:BPI: Consultancy; Bayer: Consultancy; Hema Biologics: Consultancy; Shire: Consultancy; Bioverativ: Other: PI in clinical research study. Thornburg:ATHN: Research Funding; Bayer Pharmaceuticals: Research Funding; Biomarin: Consultancy; CSL Behring: Research Funding; Bioverativ: Consultancy; Genentech: Speakers Bureau; Octapharma: Research Funding; NovoNordisk: Research Funding; Shire: Research Funding; Johns Hopkins All Children's Hospital: Research Funding; Bluebird Bio: Consultancy.

Factor VIII cross-matches to the human proteome reduce the predicted inhibitor risk in missense mutation hemophilia A.

Single missense mutations in the F8 gene encoding the coagulation protein factor VIII give rise predominantly to non-severe hemophilia A. Despite only a single amino acid sequence difference between the replacement, therapeutic factor VIII and the patient’s endogenous factor VIII, therapeutic factor VIII may still be perceived as foreign by the recipient’s immune system and trigger an immune response (inhibitor). Inhibitor formation is a life-long risk for patients with non-severe hemophilia A treated with therapeutic factor VIII, but remains difficult to predict. The aim of this study was to understand whether fortuitous, primary sequence cross-matches between therapeutic factor VIII and proteins in the human proteome are the reason why certain F8 mutations are not associated with inhibitor formation. We predicted which therapeutic factor VIII differences are potentially perceived as foreign by helper T cells – a necessary precursor to inhibitor development – and then scanned potentially immunogenic peptides against more than 100,000 proteins in the proteome. As there are hundreds of disease-causing F8 missense mutations and the human leukocyte antigen gene complex governing peptide presentation to helper T cells is highly polymorphic, these calculations pose a huge combinatorial challenge that we addressed computationally. We found that cross-matches between therapeutic factor VIII and the human proteome are commonplace and have a profound impact on the predicted risk of inhibitor development. Our results emphasize the importance of knowing both the F8 missense mutation and the human leukocyte antigen alleles of a patient with missense mutation hemophilia A if his underlying risk of inhibitor development is to be estimated.

The frequency of joint hemorrhages and procedures in nonsevere hemophilia A vs B

AbstractData are needed on minimal factor activity (FA) levels required to prevent bleeding in hemophilia. We aimed to evaluate associations between hemophilia type and FA level and joint bleeding and orthopedic procedures using longitudinal data. Data were collected over an 11-year period on males with nonsevere hemophilia A or B without inhibitors who were receiving on-demand factor replacement therapy. Data on the number of joint bleeds in the previous 6 months and data on procedures from clinical records were analyzed using regression models. Data were collected on 4771 patients (hemophilia A, 3315; hemophilia B, 1456) from 19 979 clinic visits. Ages ranged from 2 to 91 years and baseline FA level ranged from 1% to 49% with a mean of 9.4%. Joint bleeding rates were heterogeneous across the FA range and were highest among men age 25 to 44 years. Adjusted for FA level, the mean number of joint bleeds per 6 months was 1.4 and 0.7 for patients with hemophilia A and B, respectively (P < .001). Regression models predicted 1.4 and 0.6 bleeds per year for hemophilia A and B patients, respectively, at an FA level of 15%. Patients with hemophilia B were 30% less likely than those with hemophilia A to have undergone an orthopedic procedure. We conclude that joint bleed rates for any given FA level were higher among hemophilia A than hemophilia B patients, and target FA levels of 15% are unlikely to prevent all joint bleeding in US males with hemophilia.

HLA-DRB1–factor VIII binding is a risk factor for inhibitor development in nonsevere hemophilia: a case-control study

AbstractDevelopment of anti-factor VIII (FVIII) inhibitory antibodies (inhibitors) is the most significant treatment complication of hemophilia A. Characteristics of the interaction between major histocompatibility complex (MHC) class II and FVIII peptides may influence FVIII antigen presentation to T cells and subsequent inhibitor development. We analyzed predicted HLA-DRB1, a subset of MHC class II, and FVIII peptide binding and its association with inhibitor development among subjects with nonsevere hemophilia A, including 20 cases (inhibitor titer ≥ 1.0 BU/mL on 2 occasions or on 1 occasion with subsequent immune tolerance induction) and 37 controls (who had received FVIII infusions and did not develop inhibitor). Using the MHC-II Binding Predictions Tool (https://www.iedb.org), the binding affinity and core binding were determined for endogenous FVIII (eFVIII) and treatment FVIII (tFVIII). A tFVIII peptide was considered novel if it was predicted to bind and present a surface to the T-cell receptor that was unique from that presented by eFVIII. Having >10 novel HLA-DRB1 allele–tFVIII peptide combinations was associated with inhibitor development (adjusted odds ratio, 4.1; 95% confidence interval, 1.1-15.0). Cases and controls with p.Arg612Cys and p.Arg2169His demonstrated a high level of novel HLA-DRB1–tFVIII peptide combinations. Assessing the likelihood that tFVIII is presented to T cells in a novel fashion may be useful for understanding and ultimately reducing the risk for inhibitor development among patients with nonsevere hemophilia, particularly those with F8 mutations other than p.Arg612Cys and p.Arg2169His.

Desmopressin in non-severe haemophilia A: Test-response and clinical outcomes in a single Canadian centre review.

Desmopressin is an effective haemostatic agent for patients with non-severe haemophilia A; however, response may differ between patients of similar severity. Responsiveness is classified based on various cut-off values for plasma levels of FVIII post-desmopressin administration. Patients may be classified differently depending on the values chosen. To classify desmopressin response in non-severe haemophilia A patients with respect to current test-response definitions. Also, to characterize relationships between test response and clinical outcome of desmopressin use. Current desmopressin test-response definitions were obtained from the literature. We adopted peak FVIII level (at 1hour post-administration) ≥50 IU/dL and <20 IU/dL as complete and no response, respectively, thereby satisfying most reported definitions. Test-responses and clinical outcomes of use between 2007 and 2017 for adult mild/moderate haemophilia A patients were reviewed and correlated. All patients classified as complete responders (n=31; peak FVIII ≥50 IU/dL) and the majority of partial responders (n=11; peak FVIII ≥20 to <50 IU/dL) had good clinical outcomes after desmopressin use for a variety of bleeding episodes and procedures. Two non-responders (peak FVIII <20 IU/dL) given desmopressin for minor bleeding/procedures also had good clinical outcomes. One patient with a partial test-response (peak FVIII 23 IU/dL) required additional factor concentrate to achieve haemostasis. Based on our review, we suggest that the determination of desmopressin responsiveness should consider both the change in plasma FVIII levels as well as clinical outcomes associated with prior therapeutic use.

Pharmacokinetic Modelling to Predict FVIII:C Response to Desmopressin and Its Reproducibility in Nonsevere Haemophilia A Patients.

Nonsevere haemophilia A (HA) patients can be treated with desmopressin. Response of factor VIII activity (FVIII:C) differs between patients and is difficult to predict. Our aims were to describe FVIII:C response after desmopressin and its reproducibility by population pharmacokinetic (PK) modelling. Retrospective data of 128 nonsevere HA patients (age 7-75 years) receiving an intravenous or intranasal dose of desmopressin were used. PK modelling of FVIII:C was performed by nonlinear mixed effect modelling. Reproducibility of FVIII:C response was defined as less than 25% difference in peak FVIII:C between administrations. A total of 623 FVIII:C measurements from 142 desmopressin administrations were available; 14 patients had received two administrations at different occasions. The FVIII:C time profile was best described by a two-compartment model with first-order absorption and elimination. Interindividual variability of the estimated baseline FVIII:C, central volume of distribution and clearance were 37, 43 and 50%, respectively. The most recently measured FVIII:C (FVIII-recent) was significantly associated with FVIII:C response to desmopressin (p < 0.001). Desmopressin administration resulted in an absolute FVIII:C increase of 0.47 IU/mL (median, interquartile range: 0.32-0.65 IU/mL, n = 142). C response was reproducible in 6 out of 14 patients receiving two desmopressin administrations. FVIII:C response to desmopressin in nonsevere HA patients was adequately described by a population PK model. Large variability in FVIII:C response was observed, which could only partially be explained by FVIII-recent. C response was not reproducible in a small subset of patients. Therefore, monitoring FVIII:C around surgeries or bleeding might be considered. Research is needed to study this further.