A consensus statement on clinical trials of bypassing agent prophylaxis in inhibitor patients

Spanish Consensus Guidelines on prophylaxis with bypassing agents in patients with haemophilia and inhibitors

Prophylaxis with the blood clotting factor, factor VIII (FVIII) is ineffective for individuals with haemophilia A and high-titre inhibitors to FVIII. Prophylaxis with the FVIII bypassing agents activated prothrombin complex concentrates (aPCC; FEIBA® Baxalta) or recombinant activated factor VII (rFVIIa; Novo-Seven®, Novo Nordisk) may be an effective alternative. It was our aim to develop evidence -and expert opinion- based guidelines for prophylactic therapy for patients with high-titre inhibitors to FVIII. A panel of nine Spanish haematologists undertook a systematic review of the literature to develop consensusbased guidance. Particular consideration was given to prophylaxis in patients prior to undergoing immune tolerance induction (ITI) (a process of continued exposure to FVIII that can restore sensitivity for some patients), during the ITI period and for those not undergoing ITI or for whom ITI had failed. These guidelines offer guidance for clinicians in deciding which patients might benefit from prophylaxis with FVIII bypassing agents, the most appropriate agents in various clinical settings related to ITI, doses and dosing regimens and how best to monitor the efficacy of prophylaxis. The paper includes recommendations on when to interrupt or stop prophylaxis and special safety concerns during prophylaxis. These consensus guidelines offer the most comprehensive evaluation of the clinical evidence base to date and should be of considerable benefit to clinicians facing the challenge of managing patients with severe haemophilia A with high-titre FVIII inhibitors.

Physician preferences for medication attributes for the prophylactic treatment of patients with severe haemophilia A with inhibitors to factor VIII

Prophylaxis may be beneficial for patients with severe haemophilia A who have developed inhibitors to factor VIII. The aim of this study was to determine physicians' preferences for medication attributes in the prophylactic treatment of this patient population. Haematologists from Europe (EU) and the United States (US) participated in a discrete choice exercise to explore their preferences for medication attributes (efficacy, cost, scientific evidence, dosing frequency and administration time) associated with prophylaxis for severe haemophilia A in patients with inhibitors to factor VIII. Physicians' preferences for medication attributes were assessed through completion of 25 trade-off tasks that included a choice between two hypothetical medications each comprised of one randomized level of each medication attribute. Participants also completed a sociodemographic questionnaire. Data were analysed using a random effects logit model. Participants (N = 36: US = 19; EU = 17) were 80.6% men, had a mean of 19.8 years (SD ± 8.1) [range 6-35] of practice experience. The physicians treated an average of 5.7 (± 5.5) patients with severe haemophilia A and inhibitors per month and reported treating 36.2% of these patients prophylactically. The most important medication attributes for prophylactic treatment were efficacy [Relative Importance (RI) = 35.0%] and scientific evidence (RI = 34.1%), whereas treatment cost (12.0%), dosing frequency (10.8%) and administration time (8.2%) were less important. Results were similar across the EU and US. Efficacy and scientific evidence are the primary considerations for physicians' choice of prophylactic medications for use in this patient population.