Understanding inhibitor development in haemophilia A: towards clinical prediction and prevention strategies

A Systematic Review of Efficacy and Safety of Plasma-Derived von Willebrand Factor/Factor VIII Concentrate (Voncento) in von Willebrand Disease

BACKGROUND

 For the treatment of von Willebrand disease (VWD), von Willebrand factor (VWF) concentrates can be used in on-demand, long-term prophylaxis, and surgical prophylaxis regimens.

METHODS

 This systematic literature review was conducted to evaluate the efficacy, consumption, and safety of plasma-derived human coagulation FVIII/human VWF (pdVWF/FVIII; Voncento/Biostate) for the treatment of patients with any inherited VWD type. An electronic search was conducted in MEDLINE and Cochrane Library databases on VWD therapies. All retrieved publications were assessed against predefined inclusion/exclusion criteria following the Cochrane group recommendations. Associated pharmacovigilance data were collected across the same time period.

RESULTS

 Eleven publications from eight study cohorts were identified for data retrieval. All were from multicenter studies and included both pediatric and adult patients. Eight publications included evaluations of the efficacy of pdVWF/FVIII for on-demand treatment, eight included long-term prophylactic treatment, and eight included surgical prophylaxis. Treatment protocols and VWF administration methods differed between studies, as did safety evaluations. The clinical response was rated as excellent/good for on-demand treatment in 66 to 100% of nonsurgical bleeds, 89 to 100% in the treatment of breakthrough bleeds during long-term prophylaxis treatment, and hemostatic efficacy in surgical procedures was 75 to 100%. Pharmacovigilance data confirmed a low incidence of adverse events in treated patients.

CONCLUSION

 This review provides a comprehensive summary of studies that evaluated the use of pdVWF/FVIII in VWD demonstrating the long-term effectiveness and safety of this pdVWF/FVIII across all ages, types of VWD, and treatment settings.

Evaluation of the care pathway in the context of the dispensing of emicizumab (Hemlibra) in community and hospital pharmacies in France: A patient satisfaction survey

INTRODUCTION

Since June 2021 in France, patients with haemophilia A with anti-factor VIII inhibitors and patients with severe haemophilia A without anti-factor VIII inhibitors, and treated with emicizumab (Hemlibra), have to choose the dispensing circuit community or hospital pharmacy.

AIM

To evaluate satisfaction of patients whether they choose dispensation from a community pharmacy or retained dispensation from the hospital pharmacy, to understand the main motivation for choosing the community or the hospital pharmacy.

METHODS

All patients living in France, regardless of age, were eligible to participate. Between September 13, 2022, and January 9, 2023, 175 respondents answered the satisfaction survey, including 123 in community pharmacy and 52 in hospital pharmacy.

RESULTS

Eighteen months after availability in community pharmacies, treatment accessibility is improved for the benefit of the patient. The door-to-door travel times are significantly reduced to the community pharmacy with an average gain of 16.5 min saved from the place of residence. Patients are mostly satisfied with the new dispensing circuit especially concerning the overall satisfaction (p < .0001), the travel time (p < .0001) and the strong relationship with the pharmacist (p = .0022) compared to hospital pharmacy.

CONCLUSION

Innovation in care pathways is showing its full potential in improving access to medication, made possible by the implementation of a rigorous organization accompanied by training to enable healthcare professionals involved in primary care to provide appropriate management.

Frequency of Specific and Non-specific Inhibitors in Haemophilia A Patients

Objective: To determine the frequency of specific and non-specific inhibitors in haemophilia A patients.

Study design: This is a cross-sectional study.

Patients and methods: A total of 150 male haemophilia A patients were included in this cross-sectional study at the National Institute of Blood Diseases and Bone Marrow Transplant (NIBD), Karachi, Pakistan, from September 2019 to January 2022.

Results: Among 150 patients included in this study, 23 (15.3%) had an inhibitor and 127 (84.6%) did not. All patients had specific inhibitors against Factor VIII (FVIII). Non-specific inhibitors were not identified in our population. Among the patients in the inhibitor group, there were 13 (56.5%) in the severe (<1%) category. There were 10 (43.5%) patients in the moderate (1-5%) category. There were no patients in the mild category. The median inhibitor level was 15.4 Bethesda unit (BU).

Conclusion: The development of inhibitors has not been identified as a major problem in our population. However, it is noteworthy that only 15.3% of patients with haemophilia A developed inhibitors in this data set. They were essentially treated with plasma and its products.

Acute coronay syndrome in a patient with severe hemophilia A: Dificult decisions

Hemophilia A is an inherited coagulation disease characterized by factor VIII (FVIII) deficiency and is associated with high hemorrhagic risk, especially in its severe forms. As the average life expectancy of patients with hemophilia has increased, so has the prevalence of acute coronary events. There is however limited experience in dealing with them. The strategy of acting on acute coronary events in patients with hemophilia, as demonstrated in the present case, is a real challenge, not only due to the need for antiplatelet therapy (which is essential in the prevention of stent thrombosis, but increases hemorrhagic risk), but also due to the lack of specific recommendations related to the most adequate and safe replacement therapy in these situations. The authors describe the case of a 48-year-old man with unstable angina and a previous diagnosis of severe hemophilia A who underwent percutaneous coronary intervention under FVIII therapy without hemorrhagic complications.

ABO Blood Group and Inhibitor Risk in Severe Hemophilia A Patients: A Study from the Italian Association of Hemophilia Centers

Considering the profound influence exerted by the ABO blood group system on hemostasis, mainly through the von Willebrand factor and factor VIII (FVIII) complex, we have conducted a study evaluating the possible role of blood type on the risk of inhibitor development in hemophilia A. A total of 287 consecutive Caucasian patients with severe hemophilia A (202 without FVIII inhibitors and 85 with FVIII inhibitors) followed at seven Italian Hemophilia Treatment Centers belonging to the Italian Association of Hemophilia Centers (AICE) were included in the study. A higher prevalence of O blood group was detected in patients without inhibitors as compared in inhibitor patients (55 vs. 30.6%; p < 0.001). Among the other variables analyzed (age, F8 mutation, type and intensity of treatment and treatment regimen), F8 mutation class (high-risk vs. low-risk), and treatment regimen (on-demand vs. prophylaxis) were significantly correlated with inhibitor development. However, on a multivariate analysis, only the effects of F8 mutation and ABO blood type were independent of other covariates, being that non-O blood type is associated with a 2.89-fold increased risk of inhibitor development. In conclusion, our study supports the protective effect of O blood type on inhibitor risk in severely affected hemophilia A patients.

Inhibitor development in previously untreated patients with severe haemophilia: A comparison of included patients and outcomes between a clinical study and a registry-based study

Aim

The aim of this study was to investigate whether a disease registry could serve as a suitable alternative to clinical studies to investigate safety of orphan drugs in children.

Methods

We used individual patient data from previously untreated patients (PUPs) with severe haemophilia A from the factor VIII (rAHF‐PFM)‐clinical study and the PedNet registry. The primary outcome was the patient characteristics at entry and the difference in inhibitor development between the clinical study and the registry‐based study at 50 exposure days.

Results

Clinical study patients more often had a positive family history of inhibitors (31% vs 10%) and a high‐risk F8 genotype (82% vs 63%). In the clinical study 41/55 (75%) and in the registry‐based study 162/168 (96%) patients reached 50 exposure days. Inhibitors developed in 16 of the 41 patients in the clinical study (39%) vs 44 of the 162 patients in the registry‐based study (27%); seven patients (7%) vs 28 patients (17%) had high‐titre inhibitors. The risk of developing an inhibitor during the first 50 exposure days was similar (HR 1.04; 95% CI 0.56‐1.94), when adjusted for family history of inhibitors, F8 gene mutation and intensive treatment at first exposure.

Conclusion

In the registry‐based study, patient numbers and completeness of follow‐up were higher. The risk of developing an inhibitor to a single product was comparable. Although the sample size of this study was too small to conclude on differences in high‐ or low‐titre inhibitors, this suggests that a registry could serve as a more suitable source for evaluation of high‐titre inhibitors in the setting of factor VIII deficiency.

Relationship Between Single-Nucleotide Polymorphisms of Tumor Necrosis Factor Alpha, Interleukin-10, Factor II and Factor V with Risk of Inhibitor Development in Patients with Severe Hemophilia A

BACKGROUND

About one-fourth of patients with hemophilia A (HA) develop alloantibodies against factor (F) VIII, as the main treatment challenge. Here, we assessed the relationship between interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), FII and FV polymorphisms and risk of inhibitor formation in patients with severe HA.

METHODS

We divided 39 patients with severe HA in two groups of case (n: 19) and control (n: 20). Genotyping was performed by multiplex amplification tetra arms refractory mutation systempolymerase chain reaction (ARMS-PCR) and PCR-restriction fragment-length polymorphism (PCR-RFLP).

RESULTS

TNFα rs1800629 G>A polymorphism decreased the risk of inhibitor development in codominant and dominant inheritance pattern. Moreover, TNFα rs1800629 A allele, decrease the risk of inhibitor formation, while IL10 rs1800896 A>G, FV rs6025 G>A, and FII rs1799963 G>A polymorphisms were not associated with risk of inhibitor development.

CONCLUSION

It seems that TNFα rs1800629 G>A polymorphism decreased the risk of inhibitor formation in Iranian patients with HA.

Eptacog beta: a novel recombinant human factor VIIa for the treatment of hemophilia A and B with inhibitors

INTRODUCTION

Hemophilia A and B are X-linked recessive disorders caused by the deficiency of factor VIII or factor IX, respectively. Bleeding episodes are treated with factor replacement therapy. The most serious complication of this treatment is the development of inhibitors. In such patients, bypassing agents, such as activated recombinant human factor VII (rhFVIIa) or plasma-derived activated prothrombin complex concentrates, are administered to prevent or treat bleeding episodes. The high cost of the current bypassing agents limits their availability in emerging countries. Areas covered: Authors reviewed the published data on the development and clinical testing of eptacog beta, a new second-generation rhFVIIa produced in the milk of transgenic rabbits. The available data indicate that activated eptacog beta exhibits structural (N- and O- glycosylation), pharmacodynamic and pharmacokinetic characteristics similar to activated eptacog alfa, its main competitor, but binds slightly better to platelets and HUVEC, and it is safe and effective. Expert commentary: This critical review of available data on activated eptacog beta shows that it represents an alternative source of rhFVIIa at potentially lower cost with easily expandable manufacturing capacity that could contribute to cover the future patient needs.

Inhibitors in haemophilia A and B: Management of bleeds, inhibitor eradication and strategies for difficult-to-treat patients

The standard therapy for patients with haemophilia is prophylactic treatment with replacement factor VIII (FVIII) or factor IX (FIX). Patients who develop inhibitors against FVIII/FIX face an increased risk of bleeding, and the likelihood of early development of progressive arthropathy, alongside higher treatment-related costs. Bypassing agents can be used to prevent and control bleeding, as well as the recently licensed prophylaxis, emicizumab, but their efficacy is less predictable than that of factor replacement therapy. Antibody eradication, by way of immune tolerance induction (ITI), is still the preferred management strategy for treating patients with inhibitors. This approach is successful in most patients, but some are difficult to tolerise and/or are unresponsive to ITI, and they represent the most complicated patients to treat. However, there are limited clinical data and guidelines available to help guide physicians in formulating the next treatment steps in these patients. This review summarises currently available treatment options for patients with inhibitors, focussing on ITI regimens and those ITI strategies that may be used in difficult-to-treat patients. Some alternative, non-ITI approaches for inhibitor management, are also proposed.

Clinicopathological parameters influencing inhibitor development in patients with hemophilia A receiving on-demand therapy

BACKGROUND

Development of inhibitors to transfused factor VIII in patients with hemophilia A continues to be a challenge for professionals involved in hemophilia care. The majority of patients in India receive 'on-demand' rather than prophylactic therapy. The present study was done to assess the prevalence of factor VIII inhibitors in patients with hemophilia A (PWHA) receiving 'on-demand' therapy in a North Indian population and to study the clinicopathological parameters influencing the development of inhibitors.

METHODS

The study group comprised of 300 PWHA. Detailed clinical parameters, treatment history, bleeding profile including family history were recorded. Diagnosis of hemophilia A was confirmed by relevant coagulation tests. Inhibitors were screened using mixing based studies followed by quantification by Bethesda assay and Nijmegen modified Bethesda assay. Samples were collected from five cities in North India where a free supply of factor VIII was available and effectively used in three of these cities.

RESULTS

In the 300 PWHA, disease phenotype was severe in 219 (73%), moderate in 62 (20.67%) and mild in 19 (6.34%), based on the factor VIII bioassay. Inhibitor prevalence was 9.6% (n = 29) and seen only in the severe phenotype. Inhibitor titers ranged from 0.8 to 108.8 BU/ml. A total of 12 PWHA had low and 17 had high titers. Correlation of various clinicopathological parameters in inhibitor-positive versus negative PWHA showed significant correlation with age at onset of disease, severity of disease, age at first exposure to treatment, annual factor intake (IU/kg/year), intense treatment episodes and bleeding manifestations like central nervous system bleed and hematuria. The total study sample had blood group B in 33.34% PWHA, followed by O (27.34%), A (24.34%) and AB (15%), however, in inhibitor-positive samples, significant inhibitor formation was associated with the ABO subtype A (19/29, 65.51%).

CONCLUSIONS

Factor VIII inhibitor prevalence in PWHA receiving 'on-demand' therapy was 9.6%. Clinicopathological correlates of inhibitor development in such PWHA have been analyzed in this novel study.

Safety of fascial therapy in adult patients with hemophilic arthropathy of ankle. A cohort study

BACKGROUND

Hemophilic arthropathy is characterized by loss of function and chronic pain. Fascial therapy mobilizes the connective tissue, intervening in the state of the injured fascial complex and the surrounding tissues.

OBJECTIVES

The aim of this study is to evaluate the safety of a physiotherapy program through fascial therapy in adult patients with hemophilic ankle arthropathy.

DESIGN

Prospective cohort study.

METHODS

Twenty-three adult patients with hemophilia from 26 to 65 years of age were recruited. The intervention consisted of three sessions of 45-minute fascial therapy for three consecutive weeks. An evaluation was carried out before as well as after treatment. The study variables were joint status (assessed with Hemophilia Joint Health Score), joint pain (using visual analogue scale), ankle range of motion (with a universal goniometer) and bleeding frequency (administering self-registration of bleeding). The mean difference was calculated using the Student's t-test for paired samples and using the Cohen formula we calculated the effect size of the dependent variables.

RESULTS

None of the patients developed muscular or articular bleeding during the treatment period. After treatment, significant improvements (p < 0.05) in plantar flexion, ankle pain under load and joint condition were observed in both ankles. Similarly, we found improvement in left ankle dorsiflexion.

CONCLUSIONS

The application of physiotherapy through fascial therapy does not appear to produce muscle or joint hemorrhages. A treatment through three sessions of fascial therapy may improve joint pain, mobility and joint ankle condition in patients with hemophilic arthropathy.

Low incidence of factor VIII inhibitors in previously untreated patients with severe haemophilia A treated with octanate® : Final report from a prospective study

INTRODUCTION

Octanate^® is a human, plasma-derived, von Willebrand factor-stabilized coagulation factor VIII (FVIII) concentrate with demonstrated haemostatic efficacy in previously treated patients with haemophilia A.

AIM

This prospective, open-label study aimed to assess the immunogenicity of octanate^® in previously untreated patients (PUPs).

METHODS

The study monitored development of FVIII inhibitors in 51 PUPs. Tolerability, viral safety, FVIII recovery and efficacy of octanate^® for the prevention and treatment of bleeds and in surgical procedures were also assessed.

RESULTS

Five (9.8%) of the 51 patients developed inhibitors during the study, 4 of which (7.8%) were high titre. Three inhibitor cases (5.9%) were considered clinically relevant; 2 were transient inhibitors that disappeared during regular octanate^® treatment without a change in dose or treatment frequency. Amongst 45 patients with FVIII:C <1% at baseline and who received ≥20 exposure days (EDs) or had <20 EDs but developed an inhibitor, inhibitor incidence was 11.1% (6.7% clinically relevant). All clinically relevant inhibitors developed within 20 EDs of on-demand treatment. No inhibitors developed in PUPs receiving prophylaxis. All patients who developed inhibitors had either intron 22 inversions or large deletions. Irrespective of the reason for administration, haemostatic efficacy was rated as "excellent" in 99.6% of all infusions (4700 of 4717 infusions), and no complications were reported in 23 surgical procedures. Mean incremental in vivo recovery was 2.0%/IU/kg (±0.7) and 1.9%/IU/kg (±0.5) for the first and second assessments, respectively. Tolerability was rated "very good" in 99.9% of infusions.

CONCLUSION

In PUPs with severe haemophilia A, octanate^® demonstrated haemostatic efficacy with a low rate of inhibitor development.

Global Post-Authorization Safety Surveillance Study: real-world data on prophylaxis and on-demand treatment using FEIBA (an activated prothrombin complex concentrate)

This prospective, Post-Authorization Safety Surveillance (PASS) study was carried out in patients with hemophilia A or B and inhibitors treated with FEIBA for 1 year to collect real-world data on safety and effectiveness of FEIBA. The study followed a cohort design and did not make stipulations on treatment or observation schedule, as it was designed to observe routine medical practices based on physicians’ treatment decisions, including whether patients received on-demand or prophylaxis with FEIBA. The attending physician maintained documentation, including medical records, laboratory reports, adverse event reports, and so on and a subject diary was used. Eighty-one patients were treated with FEIBA at 40 sites in 10 countries over a 4-year period. Sixty-nine patients (85.2%) had hemophilia A, two had (2.5%) hemophilia B, and ten (12.3%) had acquired hemophilia A. At baseline 45 patients (55.6%) were prescribed prophylaxis and 36 (44.6%) on-demand treatment. This study was novel in following safety and effectiveness in ‘real world’ on-demand and prophylactic use of FEIBA, and was able to collect data in these rare patients under routine clinical practice.

Natural history and clinical characteristics of inhibitors in previously treated haemophilia A patients: a case series

BACKGROUND

Development of inhibitors is the most serious complication in haemophilia A treatment. The assessment of risk for inhibitor formation in new or modified factor concentrates is traditionally performed in previously treated patients (PTPs). However, evidence on risk factors for and natural history of inhibitors has been generated mostly in previously untreated patients (PUPs). The purpose of this study was to examine cases of de novo inhibitors in PTPs reported in the scientific literature and to the EUropean HAemophilia Safety Surveillance (EUHASS) programme, and explore determinants and course of inhibitor development.

METHODS

We used a case series study design and developed a case report form to collect patient level data; including detection, inhibitor course, treatment, factor VIII products used and events that may trigger inhibitor development (surgery, vaccination, immune disorders, malignancy, product switch).

RESULTS

We identified 19 publications that reported 38 inhibitor cases and 45 cases from 31 EUHASS centres. Individual patient data were collected for 55/83 (66%) inhibitor cases out of 12 330 patients. The median (range) peak inhibitor titre was 4.4 (0.5-135.0), the proportion of transient inhibitors was 33% and only two cases of 12 undergoing immune tolerance induction failed this treatment. In the two months before inhibitor development, surgery was reported in nine (22%) cases, and high intensity treatment periods reported in seven (17%) cases.

CONCLUSIONS

By studying the largest cohort of inhibitor development in PTPs assembled to date, we showed that inhibitor development in PTPs, is on average, a milder event than in PUPs.

Bayesian approach to the assessment of the population-specific risk of inhibitors in hemophilia A patients: a case study

Background

Developing inhibitors is a rare event during the treatment of hemophilia A. The multifacets and uncertainty surrounding the development of inhibitors further complicate the process of estimating inhibitor rate from the limited data. Bayesian statistical modeling provides a useful tool in generating, enhancing, and exploring the evidence through incorporating all the available information.

Methods

We built our Bayesian analysis using three study cases to estimate the inhibitor rates of patients with hemophilia A in three different scenarios: Case 1, a single cohort of previously treated patients (PTPs) or previously untreated patients; Case 2, a meta-analysis of PTP cohorts; and Case 3, a previously unexplored patient population – patients with baseline low-titer inhibitor or history of inhibitor development. The data used in this study were extracted from three published ADVATE (antihemophilic factor [recombinant] is a product of Baxter for treating hemophilia A) post-authorization surveillance studies. Noninformative and informative priors were applied to Bayesian standard (Case 1) or random-effects (Case 2 and Case 3) logistic models. Bayesian probabilities of satisfying three meaningful thresholds of the risk of developing a clinical significant inhibitor (10/100, 5/100 [high rates], and 1/86 [the Food and Drug Administration mandated cutoff rate in PTPs]) were calculated. The effect of discounting prior information or scaling up the study data was evaluated.

Results

Results based on noninformative priors were similar to the classical approach. Using priors from PTPs lowered the point estimate and narrowed the 95% credible intervals (Case 1: from 1.3 [0.5, 2.7] to 0.8 [0.5, 1.1]; Case 2: from 1.9 [0.6, 6.0] to 0.8 [0.5, 1.1]; Case 3: 2.3 [0.5, 6.8] to 0.7 [0.5, 1.1]). All probabilities of satisfying a threshold of 1/86 were above 0.65. Increasing the number of patients by two and ten times substantially narrowed the credible intervals for the single cohort study (1.4 [0.7, 2.3] and 1.4 [1.1, 1.8], respectively). Increasing the number of studies by two and ten times for the multiple study scenarios (Case 2: 1.9 [0.6, 4.0] and 1.9 [1.5, 2.6]; Case 3: 2.4 [0.9, 5.0] and 2.6 [1.9, 3.5], respectively) had a similar effect.

Conclusion

Bayesian approach as a robust, transparent, and reproducible analytic method can be efficiently used to estimate the inhibitor rate of hemophilia A in complex clinical settings.

Identification of mutations in the F8 and F9 gene in families with haemophilia using targeted high-throughput sequencing

INTRODUCTION

At present, many methods are available for the genetic diagnosis of haemophilia, including indirect linkage analysis, direct sequencing. However, these methods are time-consuming, labourious, and limited in their application. Therefore, the development of new, more effective techniques is necessary.

AIM

To detect the F8 and F9 gene mutations in patients with haemophilia and their female relatives in 29 haemophilia A (HA) and 11 haemophilia B (HB) families.

METHODS

FVIII

C and FIX:C were analyzed using one-stage method, and factor VIII and factor IX inhibitors were tested using the Bethesda method. Intron 22 and one inversions were identified using long-distance polymerase chain reaction (PCR) and standard PCR. Non-inversion mutations of the F8 and F9 gene were identified by targeted high-throughput sequencing. All mutations were verified by Sanger sequencing.

RESULTS

Intron 22 inversion was detected in eight HA families and intron one inversion was detected in one HA family. Apart from the inversion mutations, 20 mutations were identified in HA families, including 17 previously reported and three novel mutations: c.5724G>A (p.Trp1908*), c.6116-1_6120delGAGTGTinsTCC (p.Lys2039Ilefs*13), and c.5220-2A>C. We found a complex rearrangement in HA: intron one inversion concomitant with exon one deletion. In HB, eight recurrent mutations were detected, including six missense mutations and two nonsense mutations.

CONCLUSION

Targeted high-throughput sequencing is an effective technique to detect the F8 and F9 gene mutations, especially for the discovery of novel mutations. The method is highly accurate, time-saving and shows great advantage in uncovering large deletion mutations and also in distinguishing the wild-type genotype and heterozygous large deletions.

Non-genetic risk factors and their influence on the management of patients in the clinic

The development of inhibitors is the most serious iatrogenic complication affecting patients with haemophilia. This complication is associated with impaired vital or functional prognosis, reduced quality of life and increased cost of treatment. The reasons why some patients develop antibodies to factor replacement and others do not remain unclear. It is however clear that inhibitor development results from a complex multifactorial interaction between genetic and non-genetic risk factors. Environmental influences implicated in increasing the risk of inhibitor formation can be viewed as modifiable risk factors. Therefore, identification of the non-genetic risk factors may offer the possibility of personalising haemophilia therapy by modifying treatment strategies in high-risk patients in the critical early phase of factor VIII exposure. In this article, we review the non-genetic factors reported as well as the potential impact of danger signals and the different scores for inhibitor development risk stratification.

Prevalence of IVS10nt-18G/A in Calabrian patients with moderate/mild hemophilia A and relation with Factor VIII inhibitor antibodies

Hemophilia A is an X-linked bleeding disorder caused by widespread mutations in the factor VIII gene. In the course of a screening to research some hemophilia A mutations, our team has identified and posted a previously unreported nucleotide change in intron 10 in 20 patients with hemophilia A. We tried to identify a possible blood relationship between the people with this mutation, performing a backwards study of every family tree. First, we interviewed the patients and, if possible, parents and grandparents. When direct memory was no longer available, we consulted Registries of Births, Marriages and Deaths, and if these data were not sufficient, going backwards in time, we consulted registries of parish churches where newborns were baptized. The studied mutation was present in 33 hemophilic patients living in Calabria, 28 of them related. Three patients, carriers of this mutation, developed an FVIII inhibitor. In all the cases, the inhibitor development followed intensive treatments, after many days of exposure. Our study displayed the presence of a responsible moderate hemophilia A mutation, limited apparently to our country, probably because of a single ancestral event, and connected with FVIII inhibitor development.

Current management of the hemophilic child: a demanding interlocutor. Quality of life and adequate cost-efficacy analysis

Hemophilias are the most known inherited bleeding disorders. The challenges in the management of hemophilic children are different from those in adults: prophylaxis regimen removed the hallmark of crippling disease with lifelong disabilities; individualized regimens are being implemented in order to overcome venous access problems. Presently, at least in high-income countries, advances in treatment of hemophilia resulted in continuous improvement of the patients' quality of life and life expectancy. Inhibitors remain the most severe complication of hemophilia therapy. The treatment' compliance is the key to achieve a successful management. The patient, his family, the medical and psychological team are the players of a comprehensive care system. The current management of hemophilic children is the example of huge resource investments enabling long-term benefits in particular quality of life as a primary objective of the healthcare process.

Genetic factors influencing inhibitor development in a cohort of South African haemophilia A patients

A critical complication of factor VIII (FVIII) replacement therapy in Haemophilia A (HA) treatment is inhibitor development. Known genetic factors predisposing to inhibitor development include FVIII (F8) gene mutations, ethnicity, a family history of inhibitors and FVIII haplotype mismatch. The aim of this study was to characterize and correlate these genetic factors in a cohort of South African HA patients. This was a retrospective study that included 229 patients and involved the analysis of patient files, HA molecular and clinical databases and molecular analysis of the F8 gene haplotype. Of the 229 patients, 51% were of black ethnicity, 49% were white, 5% had mild HA, 4% were moderate and 91% were severe, 36% were int22 positive and 13% were inhibitor positive. Of the inhibitor positive patients, 72% were black patients. Inhibitors were reported in 27% of black int22 positive patients, 13% of black int22 negative patients, 9% of white int22 positive patients and 7% of white int22 negative. The H1 haplotype was more common in whites (75%) and H2 was more common in blacks (74%). H3 and H5 were only found in black patients and had a higher frequency of inhibitor development than H1 and H2. In this small HA cohort, black patients had a significantly higher frequency of inhibitor development and the results were indicative of an association between inhibitor development, ethnicity and haplotype.

Prophylaxis with anti-inhibitor coagulant complex improves health-related quality of life in haemophilia patients with inhibitors: results from FEIBA NF Prophylaxis Study

The Pro-FEIBA study reported health-related quality of life (HRQoL) improved following 6-month of Factor Eight Inhibitor Bypassing Activity (FEIBA) prophylaxis. This study investigates whether 12-month of FEIBA prophylaxis improved HRQoL in haemophilia patients with inhibitors. Thirty-six subjects in a 1-year prospective, randomized, open-label, parallel-design study were randomized to prophylaxis (85 ± 15 U kg(-1) every other day) or on-demand treatment. HRQoL was assessed at screening, 6 and 12-month termination using the EQ-5D, Haem-A-QoL, Haemo-QoL and a general pain visual analog scale (VAS). To evaluate changes, paired t-tests and criteria for minimally important differences were applied. Repeated measures regression tested the association between annualized bleeding rate (ABR) and physical HRQoL. At 6 and 12 months, prophylaxis subjects reported clinically meaningful improvement in EQ-5D index (mean improvement, 0.10 and 0.08, respectively) and both clinically meaningful and statistically significant improvements in EQ-VAS scores (16.9 and 15.7, respectively; P < 0.05) vs. baseline. General pain was significantly reduced during prophylaxis at each follow-up (mean improvement, 20.3 and 23.2, respectively; both P <0.05). At 12 months, prophylaxis subjects achieved significant improvements in Haem-A-QoL Total Score and in four domains: Physical Health, Feeling, View, and Work and School (all P < 0.05). No statistically significant changes, except for Haem-A-QoL Physical Health at 6 months, were observed with on-demand treatment. ABR was decreased by 72.5% with prophylaxis vs. on-demand treatment (P = 0.0003) and reduced ABR was associated with better physical HRQoL (P < 0.05). FEIBA prophylaxis significantly reduced ABR and improved HRQoL in inhibitor patients. Subjects with lower ABR reported better physical HRQoL.

A Polymorphism in the IL-5 Gene is Associated with Inhibitor Development in Severe Hemophilia A Patients

OBJECTIVE

A severe complication in the replacement therapy of hemophilia A (HA) patients is the development of alloantibodies (inhibitors) against factor VIII, which neutralizes the substituted factor. The primary genetic risk factors influencing the development of inhibitors are F8 gene mutations. Interleukins and cytokines that are involved in the regulation of B-lymphocyte development are other possible targets as genetic risk factors. This study assesses the possible involvement of 9 selected single nucleotide gene polymorphisms (SNPs) with interleukins (IL-4, IL-5, and IL-10), transforming growth factor beta 1 (TGF-β1), and interferon gamma (IFN-γ) in inhibitor development in severely affected HA patients carrying a null mutation in the F8 gene.

MATERIALS AND METHODS

A total of 173 HA patients were screened for intron 22 inversion and null mutations (nonsense and deletions). Genotyping of a total of 9 SNPs in genes IL-4, IL-5, IL-10, TGF-β1, and IFN-γ in 103 patients and 100 healthy individuals was carried out.

RESULTS

An association analysis between 42 inhibitor (+) and 61 inhibitor (-) patients showed a significant association with the T allele of rs2069812 in the IL-5 gene promoter and patients with inhibitors (p=0.0251). The TT genotype was also significantly associated with this group with a p-value of 0.0082, odds ratio of about 7, and confidence interval of over 90%, suggesting that it is the recessive susceptibility allele and that the C allele is the dominant protective allele.

CONCLUSION

The lack of other variants in the IL-5 gene of patients and controls suggests that rs2069812 may be a regulatory SNP and may have a role in B-lymphocyte development, constituting a genetic risk factor in antibody development.

Prevalence, incidence, and factor concentrate usage trends of hemophiliacs in Taiwan

PURPOSE

Hemophilia A and B (HA, HB) are the most common X-linked inherited bleeding disorders. The introduction of factor concentrates has allowed for control of the lifelong chronic disease. However, no studies have been published regarding the epidemiology of hemophilia in Taiwan. Our aim was to determine the prevalence, incidence, and mortality rate, as well as trends in the use of factor concentrates, in individuals with hemophilia in Taiwan.

MATERIALS AND METHODS

A retrospective study was conducted using the National Health Insurance Research Database between 1997 and 2007.

RESULTS

We identified 988 males with hemophilia (HA : HB ratio=5.4 : 1). The mean prevalence per 100000 males was 6.7 ± 0.1 for HA and 1.2 ± 0.1 for HB. The estimated mean annual incidence per live male birth was 1 in 10752 for HA and 1 in 47619 for HB. Standardized mortality ratios for males with hemophilia (all severities) or severe hemophilia were 1.3- and 2.1-fold higher than that of the general male population, respectively. Mean factor VIII (FVIII) and factor IX (FIX) usage was 1.5003 ± 0.4029 and 0.3126 ± 0.0904 international units (IUs) per capita, respectively. Mean FVIII and FIX usage per patient with hemophilia (all severities) or severe hemophilia was 44027 ± 11532 and 72341 ± 17298, respectively, and 49407 ± 13015 and 74369 ± 18411 IUs per person with HA or HB, respectively.

CONCLUSION

Our data revealed epidemiologic and factor concentrate usage trends in males with hemophilia in Taiwan, highlighting a need for improvements in the mandatory National Health Insurance registry. A better- designed, patient-centered registry system would enable more detailed patient information collection and analysis, improving subsequent care.

Immune tolerance induction for patients with severe hemophilia A: a critical literature review

The development of inhibitors that neutralize the function of clotting factor VIII (FVIII) is currently the most challenging complication associated with the treatment of hemophilia A as it increases the disease-related morbidity and mortality. Immune tolerance induction (ITI) is the only documented strategy to eradicate persistent inhibitors in severe hemophilia A patients. Several studies have been conducted so far to identify patient- and treatment-related factors associated with greater ITI success. The currently available literature on ITI in hemophilia A will be critically reviewed in this article. In particular, we will focus on the role of the type of FVIII product on ITI outcome by analyzing the clinical and experimental data.

Treatment trends for haemophilia A and haemophilia B in the United States: results from the 2010 practice patterns survey

Frequent evaluation of haemophilia treatment is necessary to improve patient care. The 2010 Practice Patterns Survey (PPS) investigated current trends in haemophilia treatment in the United States, as reported by nurses. The aim was to document practice patterns for haemophilia A and haemophilia B Survey questionnaires were sent to nurses at haemophilia treatment centres (HTCs) across the United States. Seventy-one of 126 HTCs (56%) responded to the survey. Factor dosage across treatment modalities ranged from 20 to 50 IU kg(-1) for severe haemophilia A. Dosage for severe haemophilia B was more variable (<40 to >100 IU kg(-1)). On-demand dosing regimens were inconsistent for haemophilia A and more so for haemophilia B. Rates of adherence to prescribed treatment were similar for both haemophilia types (∼80%). The main barrier to adherence was identified as inconvenience. More bleeding episodes occurred in adults (16.6 bleeding episodes per year) with severe haemophilia A than in younger patients (11.3 bleeding episodes per year) before switching patients to prophylaxis. For both haemophilia types, most patients who switched from prophylaxis to on-demand treatment were aged 13-24 years; these patients also had the lowest adherence (60-71%). More paediatric patients with severe haemophilia A and inhibitors (53%) received prophylactic bypassing therapy than their haemophilia B counterparts (38%). Adults with severe haemophilia A faced challenges in relation to co-morbidities and long-term care. This PPS provides insights into previously unexplored aspects of haemophilia care that will serve to increase awareness and promote discussion of current issues affecting haemophilia patient care.

Self-complementary AAVs induce more potent transgene product-specific immune responses compared to a single-stranded genome

Using a mouse model we show that self-complementary (sc) adeno-associated virus (AAV) vectors pseudotyped with capsids of serotypes 2, 7 or 8 induce more potent transgene product-specific CD8(+) T cell and antibody responses compared to corresponding single-stranded (ss)AAV vectors. These data suggest that the higher and more rapidly appearing amounts of transgene product achieved with scAAV vectors may increase detrimental immune responses in gene transfer recipients.

Surgery and inhibitor development in hemophilia A: a systematic review

BACKGROUND

Although the association between intensive treatment and the formation of inhibiting antibodies towards factor VIII (FVIII) in hemophilia A has been demonstrated, the contributing effect of surgery is presently unclear. The release of immunological danger signals resulting from tissue damage during surgery in the presence of a high FVIII antigen load may elicit the formation of FVIII antibodies. The aim of this systematic review was to investigate the role of surgery in the inhibitor risk associated with intensive treatment as compared with treatment for bleeding and prophylactic administration of FVIII.

METHODS

A comprehensive literature search was performed that identified four cohort studies and three case control studies, comprising 342 inhibitor patients among a total of 957 hemophilia A patients.

RESULTS

Intensive treatment increased the inhibitor risk, most pronounced with intensive treatment of ≥ 5 exposure days (EDs) compared with < 3 EDs (OR, 4.1; 95% confidence interval, 2.6-6.5). Pooled odds ratio for inhibitor development in severe hemophilia patients that received intensive treatment for surgery at first exposure was 4.1 (95% confidence interval, 2.0-8.4) compared with treatment for bleeding or prophylaxis. Information on continuous infusion, previously treated patients and non-severe hemophilia A was insufficient for valid meta-analyses.

CONCLUSIONS

Intensive FVIII treatment for surgery at first exposure leads to a higher inhibitor risk in hemophilia A patients compared with intensive treatment for bleeding.

Induction of tolerance to factor VIII by transient co-administration with rapamycin

BACKGROUND

Formation of inhibitory antibodies is a frequent and serious complication of factor (F) VIII replacement therapy for the X-linked bleeding disorder hemophilia A. Similarly, hemophilia A mice develop high-titer inhibitors to recombinant human FVIII after a few intravenous injections.

OBJECTIVE

Using the murine model, the study sought to develop a short regimen capable of inducing tolerance to FVIII.

METHODS

A 1-month immunomodulatory protocol, consisting of FVIII administration combined with oral delivery of rapamycin, was developed.

RESULTS

The protocol effectively prevented formation of inhibitors to FVIII upon subsequent intravenous treatment (weekly for 3.5 months). Control mice formed high-titer inhibitors and had CD4(+) T effector cell responses characterized by expression of IL-2, IL-4 and IL-6. Tolerized mice instead had a CD4(+)CD25(+)FoxP3(+) T cell response to FVIII that suppressed antibody formation upon adoptive transfer, indicating a shift from Th2 to Treg if FVIII antigen was introduced to T cells during inhibition with rapamycin. CD4(+) T cells from tolerized mice also expressed TGF-β1 and CTLA4, but not IL-10. The presence of FVIII antigen during the time of rapamycin administration was required for specific tolerance induction.

CONCLUSIONS

The study shows that a prophylactic immune tolerance protocol for FVIII can be developed using rapamycin, a drug that is already widely in clinical application. Immune suppression with rapamycin was mild and highly transient, as the mice regained immune competence within a few weeks.

Treatment of hemophilia: a review of current advances and ongoing issues

Replacement of the congenitally deficient factor VIII or IX through plasma-derived or recombinant concentrates is the mainstay of treatment for hemophilia. Concentrate infusions when hemorrhages occur typically in joint and muscles (on-demand treatment) is able to resolve bleeding, but does not prevent the progressive joint deterioration leading to crippling hemophilic arthropathy. Therefore, primary prophylaxis, ie, regular infusion of concentrates started after the first joint bleed and/or before the age of two years, is now recognized as first-line treatment in children with severe hemophilia. Secondary prophylaxis, whenever started, aims to avoid (or delay) the progression of arthropathy and improve patient quality of life. Interestingly, recent data suggest a role for early prophylaxis also in preventing development of inhibitors, the most serious complication of treatment in hemophilia, in which multiple genetic and environmental factors may be involved. Treatment of bleeds in patients with inhibitors requires bypassing agents (activated prothrombin complex concentrates, recombinant factor VIIa). However, eradication of inhibitors by induction of immune tolerance should be the first choice for patients with recent onset inhibitors. The wide availability of safe factor concentrates and programs for comprehensive care has now resulted in highly satisfactory treatment of hemophilia patients in developed countries. Unfortunately, this is not true for more than two-thirds of persons with hemophilia, who live in developing countries.

Enabling normal psychophysical development in children with hemophilia: the choice for prophylaxis

Hemophilia A and B, the congenital deficiencies of coagulation factors VIII and IX, are characterized by recurrent joint and muscle bleeding episodes and progressive musculoskeletal damage (hemophilic arthropathy). Primary prophylaxis – that is, the regular infusion of factor concentrates after the first hemarthrosis and/or before 2 years of age – is now recognized as the first-choice treatment for children with severe hemophilia. Preventing bleeding from an early age enables avoidance of the clinical impact of hemophilic arthropathy and the consequences regarding psychosocial development and quality of life for these children. Interestingly, recent data suggest a role for early prophylaxis in also preventing inhibitor development, the most serious complication of treatment in hemophilia. Secondary prophylaxis, initiated after 2 years of age or after two or more joint bleeds, aims to avoid (or delay) the progression of arthropathy. In addition, better outcomes and better quality of life have been reported with earlier treatment. This review summarizes the evidence, current clinical strategies and open issues regarding prophylxis in children with hemophilia.