Determinants of adherence and consequences of the transition from adolescence to adulthood among young people with severe haemophilia (TRANSHEMO): study protocol for a multicentric French national observational cross-sectional study.

INTRODUCTION: Severe haemophilia is a rare disease characterised by spontaneous bleeding from early childhood, which may lead to various complications, especially in joints. It is nowadays possible to avoid these complications thanks to substitutive therapies for which the issue of adherence is major. The transition from adolescence to adulthood in young people with severe haemophilia is a critical period as it is associated with a high risk of lack of adherence to healthcare, which might have serious consequences on daily activities and on quality of life. METHODS AND ANALYSIS: We present the protocol for a cross-sectional, observational, multicentric study to assess the differences between adolescents and young adults with severe haemophilia in France through the transition process, especially on adherence to healthcare. This study is based on a mixed methods design, with two complementary and consecutive phases, comparing data from a group of adolescents (aged 14-17 years) with those from a group of young adults (aged 20-29 years). The quantitative phase focuses on the determinants (medical, organisational, sociodemographic and social and psychosocial and behavioural factors) of adherence to healthcare (considered as a marker of the success of transition). The qualitative phase explores participants' views in more depth to explain and refine the results from the quantitative phase. Eligible patients are contacted by the various Haemophilia Treatment Centres participating in the French national registry FranceCoag. ETHICS AND DISSEMINATION: The study was approved by the French Ethics Committee and by the French National Agency for Medicines and Health Products Safety (number: 2016-A01034-47). Study findings will be disseminated to the scientific and medical community in peer-reviewed journals and presented at scientific meetings. Results will be popularised to be communicated via the French association for people with haemophilia to participants and to the general public. TRIAL REGISTRATION NUMBER: NCT02866526; Pre-results.

A national French noninterventional study to assess the long-term safety and efficacy of reformulated nonacog alfa.

BACKGROUND: Nonacog alfa, the recombinant Factor IX (F IX) used for the treatment of hemophilia B, was approved in Europe in 1998. A reformulated version was approved for European use in 2007. STUDY DESIGN AND METHODS: This postmarketing study, as recommended by the risk management plan, was conducted to confirm the safety of reformulated nonacog alfa in a usual care setting in France. This open-label, noninterventional, prospective, longitudinal postmarketing study comprised 19 French hemophilia centers. Patients with hemophilia B receiving reformulated nonacog alfa for prophylaxis or on-demand treatment were followed up on usual care schedule. RESULTS: A total of 58 subjects were enrolled, of whom 29 (50%) were less than 18 years of age. Hemophilia was severe (baseline F IX activity < 1%) in 47 (81%) patients. All subjects except one were already treated with reformulated nonacog alfa before enrollment. One subject was receiving reformulated nonacog alfa as immune tolerance induction at time of enrollment. At enrollment, treatment regimen was mainly prophylactic in subjects less than 18 years and on-demand in subjects 18 years or older. Median duration of follow-up in the survey was 3.3 (2.3-3.8) years. The median annualized bleeding rate was 3.9 (1.5-5.2) for prophylaxis regimen and 12.2 (3.9-22.1) for on-demand regimen. One subject, a previously untreated patient, developed F IX inhibitors during follow-up. No allergic reaction, no blood cell agglutination, no lack of efficacy or recovery, and no thrombotic events were reported. CONCLUSION: Reformulated nonacog alfa was shown to be safe in a usual care setting.

Recombinant factor VIII products and inhibitor development in previously untreated boys with severe hemophilia A.

Six recombinant factor VIII (rFVIII) products have been marketed worldwide. In 2013, the Research of Determinants of Inhibitor Development (RODIN) study group reported an unexpectedly high risk of inhibitor development with a second-generation full-length rFVIII (Product D) in previously untreated patients (PUPs) with severe hemophilia A (HA). In 1994, French public health authorities established a prospective cohort to monitor hemophilia treatment safety. A PUP subgroup was designed to investigate inhibitor risk factors. We analyzed this subcohort in view of the RODIN findings. After excluding 50 patients who participated in the RODIN study, the primary analysis focused on 303 boys with severe HA first treated with a rFVIII product. A clinically significant inhibitor was detected in 114 boys (37.6%). The inhibitor incidence was higher with Product D vs the most widely used rFVIII product (adjusted hazard ratio [aHR], 1.55; 95% confidence interval [CI], 0.97-2.49). Similar results were found for high-titer inhibitors and in 10 sensitivity analyses. No heterogeneity was observed between RODIN and our results. Combined aHRs were 1.58 (95% CI, 1.17-2.14) for all inhibitors and 1.70 (95% CI, 1.15-2.52) for high-titer inhibitors. Our results confirm the higher immunogenicity of Product D vs other rFVIII products in PUPs with severe HA.

Factor VIII products and inhibitor development in severe hemophilia A.

BACKGROUND: For previously untreated children with severe hemophilia A, it is unclear whether the type of factor VIII product administered and switching among products are associated with the development of clinically relevant inhibitory antibodies (inhibitor development). METHODS: We evaluated 574 consecutive patients with severe hemophilia A (factor VIII activity, <0.01 IU per milliliter) who were born between 2000 and 2010 and collected data on all clotting-factor administration for up to 75 exposure days. The primary outcome was inhibitor development, which was defined as at least two positive inhibitor tests with decreased in vivo recovery of factor VIII levels. RESULTS: Inhibitory antibodies developed in 177 of the 574 children (cumulative incidence, 32.4%); 116 patients had a high-titer inhibitory antibody, defined as a peak titer of at least 5 Bethesda units per milliliter (cumulative incidence, 22.4%). Plasma-derived products conferred a risk of inhibitor development that was similar to the risk with recombinant products (adjusted hazard ratio as compared with recombinant products, 0.96; 95% confidence interval [CI], 0.62 to 1.49). As compared with third-generation full-length recombinant products (derived from the full-length complementary DNA sequence of human factor VIII), second-generation full-length products were associated with an increased risk of inhibitor development (adjusted hazard ratio, 1.60; 95% CI, 1.08 to 2.37). The content of von Willebrand factor in the products and switching among products were not associated with the risk of inhibitor development. CONCLUSIONS: Recombinant and plasma-derived factor VIII products conferred similar risks of inhibitor development, and the content of von Willebrand factor in the products and switching among products were not associated with the risk of inhibitor development. Second-generation full-length recombinant products were associated with an increased risk, as compared with third-generation products. (Funded by Bayer Healthcare and Baxter BioScience.).