Inhibitor incidence in haemophilia A under exclusive use of a third-generation recombinant factor VIII concentrate: results of the HEMFIL Cohort Study

Immunogenicity of Therapeutic Biological Modalities - Lessons from Hemophilia A Therapies

The introduction and development of biologics such as therapeutic proteins, gene-, and cell-based therapy have revolutionized the scope of treatment for many diseases. However, a significant portion of the patients develop unwanted immune reactions against these novel biological modalities, referred to as immunogenicity, and no longer benefit from the treatments. In the current review, using Hemophilia A (HA) therapy as an example, we will discuss the immunogenicity issue of multiple biological modalities. Currently, the number of therapeutic modalities that are approved or recently explored to treat HA, a hereditary bleeding disorder, is increasing rapidly. These include, but are not limited to, recombinant factor VIII proteins, PEGylated FVIII, FVIII Fc fusion protein, bispecific monoclonal antibodies, gene replacement therapy, gene editing therapy, and cell-based therapy. They offer the patients a broader range of more advanced and effective treatment options, yet immunogenicity remains the most critical complication in the management of this disorder. Recent advances in strategies to manage and mitigate immunogenicity will also be reviewed.

Economic Evaluation of Immune Tolerance Induction in Children With Severe Hemophilia A and High-Responding Inhibitors: A Cost-Effectiveness Analysis of Prophylaxis With Emicizumab

OBJECTIVE

This study aimed to measure the cost-effectiveness of prophylaxis with emicizumab in PsHAhri on ITI in Brazil.

METHODS

A cost-effectiveness modeling analysis was used to estimate the costs per PsHAhri on ITI and the number of prevented bleedings from undertaking one intervention (prophylaxis with BpA) over another (prophylaxis with emicizumab), based on the Brazilian Ministry of Health perspective. Costs of ITI with recombinant FVIII, prophylaxis with BpA or emicizumab, and treated bleeding episodes with BpA costs were evaluated for PsHAhri who had ITI success or failure. This study was conducted with the perspective of the Brazilian Ministry of Health (payer).

RESULTS

During ITI, prophylaxis with BpA cost US $924 666/PsHAhri/ITI, whereas prophylaxis with emicizumab cost US $488 785/PsHAhri/ITI. During ITI, there was an average of 9.32 bleeding episodes/PsHAhri/ITI when BpA were used as prophylaxis and 0.67 bleeding/PsHAhri/ITI when emicizumab was used. By univariate deterministic sensitivity analysis, emicizumab remained dominant whichever variable was modified.

CONCLUSION

In this study, prophylaxis with emicizumab during ITI is a dominant option compared with prophylaxis with BpA during ITI.

Risk factors for antibody formation in children with hemophilia: methodological aspects and clinical characteristics of the HEMFIL cohort study

Up to 35% of patients with hemophilia A and 5% with hemophilia B develop neutralizing antibodies which can inhibit the therapeutic activity of factor replacement (inhibitors). Despite the clinical relevance of antifactor VIII and IX neutralizing antibodies, there is still a major gap on the knowledge of risk factors for their development. Furthermore, most of the studies on risk factors for inhibitor development come from Caucasian and Afro-American populations. The HEMFIL is a Brazilian prospective cohort study of previously untreated children with hemophilia, which primary aim is to identify new risk factors related to inhibitor development. This manuscript aims at describing the study design and its methodology. After the diagnosis, children are followed up to 75 exposure days or to inhibitor development. Standardized forms and blood samples are collected to describe clinical characteristics and to perform the measurement of immunological and genetic biomarkers at three time points; Inclusion time (T0), at inhibitor development or at 75 exposure days without inhibitors (T1) and after immune tolerance induction for patients in whom it is indicated and performed (T2). Currently, 120 children have been included, of whom, 95 have completed the follow-up. For severe/moderately severe hemophilia A, the cumulative incidence of inhibitors at 75 exposure days was 35% (95% confidence interval, 26-46%). The inclusion of additional patients and a longer follow-up will allow the analysis of risk factors for inhibitor development.