Use of Haemate®P as immune tolerance induction in patients with severe haemophilia A who failed previous induction attempts: a multicentre observational study

Human von Willebrand factor/factor VIII concentrates in the management of pediatric patients with von Willebrand disease/hemophilia A

Several plasma-derived intermediate and high-purity concentrates containing von Willebrand factor (VWF) and factor VIII (FVIII) are currently available. The main role of these products in the management of the pediatric population is represented by the replacement therapy in patients with severe or intermediate forms of von Willebrand disease, in whom other treatments are ineffective or contraindicated. Another important role of VWF/FVIII concentrates in children may be their use in immune tolerance induction (ITI) protocols. ITI is particularly recommended for hemophilia A children who have developed an inhibitor against FVIII, currently the most serious complication of substitutive treatment in hemophilia. Although recombinant concentrates may represent the preferred option in children with hemophilia A, VWF/FVIII concentrates may offer an advantage in rescuing patients who failed previous ITI.

Alloantibodies to therapeutic factor VIII in hemophilia A: the role of von Willebrand factor in regulating factor VIII immunogenicity

The rising incidence of neutralizing antibodies (inhibitors) against therapeutic factor VIII prompted the conduct of studies to answer the question as to whether this rise is related to the introduction of recombinant factor VIII products. The present article summarizes current opinions and results of non-clinical and clinical studies on the immunogenic potential of recombinant compared to plasma-derived factor VIII concentrates. Numerous studies provided circumstantial evidence that von Willebrand factor, the natural chaperone protein present in plasma-derived factor VIII products, plays an important role in protecting exogenous factor VIII from uptake by antigen presenting cells and from recognition by immune effectors. However, the definite contribution of von Willebrand factor in reducing the inhibitor risk and in the achievement of immune tolerance is still under debate.

Immune tolerance induction using a factor VIII/von Willebrand factor concentrate (BIOSTATE), with or without immunosuppression, in Australian paediatric severe haemophilia A patients with high titre inhibitors: a multicentre, retrospective study

INTRODUCTION

It has been postulated that factor VIII (FVIII) products containing von Willebrand factor (VWF) may improve immune tolerance induction (ITI) success rate in patients with haemophilia A and poor prognostic factors.

MATERIALS AND METHODS

We conducted a retrospective cohort analysis of a FVIII/VWF concentrate (BIOSTATE) for ITI in paediatric patients with severe haemophilia A (SHA) and inhibitors, from January 2003 to December 2011 at 3 paediatric-only Haemophilia Treatment Centres in Australia. Response to ITI was assessed at or before 33 months and at completion of ITI. Fifteen male patients with SHA were included in the analysis.

RESULTS

BIOSTATE was used for primary ITI in 8 patients (2 years, range 1.1-11.5 years) and for salvage ITI in 7 patients (9.9 years, range 1.1-15.4). At the end of the observation period there were 11 patients who achieved a complete response with BIOSTATE after a median duration of 21 months (range 5-85 months); a partial response was achieved in 2 patients in whom ITI is ongoing. Therefore, the overall response rate was 86.6%. Two patients were deemed treatment failures: one due to non-compliance after 18 months of ITI and another in whom a partial response had not been achieved after 22 months of ITI.

CONCLUSION

BIOSTATE was well-tolerated and effective when used for primary or salvage ITI in this cohort of paediatric patients with SHA and a high-level inhibitor.