Summary. Background: Antibodies to glycoprotein (GP) IIb‐IIIa and/or HLA may render platelet transfusions ineffective to stop bleeding or to cover surgery in patients with Glanzmann's thrombasthenia (GT). Anecdotal reports suggest recombinant factor (rF)VIIa might be a therapeutic alternative in these situations. Objectives: An international survey was conducted to evaluate further the efficacy and safety of rFVIIa in GT patients. Patients: We analyzed the use of rFVIIa during 34 surgical/invasive procedures and 108 bleeding episodes in 59 GT patients including 29 with current or previous antiplatelet antibodies, and 23 with a history of refractoriness to platelet transfusion. Results: rFVIIa was effective in 29 of the 31 evaluable procedures, and in 77 of the 103 evaluable bleeding episodes of which eight had a recurrence. A significantly higher success rate was observed in severe bleeding episodes when an arbitrarily defined ‘optimal regimen’ derived from the Canadian pilot study results (≥ 80 µg kg−1 rFVIIa/injection, dosing interval ≤ 2.5 h, three or more doses before failure declaration) was used compared with other regimens (77%; 24/31 vs. 48%, 19/40; χ2, P = 0.010). Patients given maintenance doses had significantly fewer recurrences within 48 h of bleed cessation compared with those not given any (Fisher's exact test, P = 0.022). One thromboembolic event and one blood clot in the ureter occurring in surgical patients following prolonged continuous infusion of high‐dose rFVIIa and antifibrinolytic drug use have been previously reported. Conclusion: rFVIIa seems a potential alternative to platelet transfusion in GT patients, particularly in those with antiplatelet antibodies and/or platelet refractoriness.
The management of patients with inhibitors is an important challenge in haemophilia care. The lack of randomized controlled trials means that clinical decisions are generally based on subjective opinions, and purchasers' attention is likely to focus on the costs of treatment. In order to assess the current management of inhibitor patients and use of immune tolerance induction therapy (ITI) in Europe, we performed a survey within a European network of 21 comprehensive care centres from 14 countries (the European Haemophilia Therapy Standardisation Board). The survey identified a total of 381 patients with inhibitors attending the centres, 211 (55.4%) of whom had never been exposed to ITI. Between 1998 and 2003, the centres performed 233 procedures and 114 (48.9%) were successful. The survey demonstrated that dosing, which is the time to start and stop the ITI, the type of concentrate to use and the definition of success varied among the centres. Well-designed trials are warranted to guide decision-making, but in the absence of these studies we have developed consensus guidance for the management of inhibitor patients based on current clinical practice, as identified by the survey, and review of the literature.
Summary. The development of inhibitors to the infused factor in patients with haemophilia is a serious clinical problem. Recent evidence suggests that alongside the strong genetic contribution to inhibitor formation, there are a number of nongenetic factors -perceived by the immune system as danger signals -which promote formation of inhibitors. This study provides a comprehensive review of clinical studies relating to these factors and also presents a survey of opinion concerning their importance and clinical influence, conducted among the members of the European Haemophilia Treatment Standardisation Board (EHTSB). Taken together, this information highlights the lack of robust data concerning the influence of several non-genetic risk factors on inhibitor development, and an urgent need for prospective, well-conducted studies that adhere to recommendations made by the European Medicines Agency (EMEA) for studying inhibitors. Based on current literature, the EHTSB formulated consensus recommendations. It is desirable to minimize intensive treatment wherever possible, given the clinical situation. Prophylaxis should be offered to all children, although we still need to determine optimal dosing with respect to inhibitor development, and age for starting treatment. Vaccinations should be given subcutaneously and concomitant factor concentrate infusions avoided. According to the board, there is no evidence in the literature supporting suggestions that the type of concentrate influences inhibitor risk; but all patients should be monitored during their first exposures. Furthermore, there is no evidence to support an association between pregnancy-related issues, breast feeding and treatment-related factors (e.g. route of administration, or use of blood components) and inhibitor development.
Introduction: Nuwiq â [human cell line-derived recombinant factor VIII (human-cl rhFVIII)] is a new generation rFVIII protein, without chemical modification or fusion to any other protein, produced in a human cell line. Aim/methods: This prospective, open-label, multinational phase III study assessed the efficacy and safety of human-cl rhFVIII in 32 adult previously treated patients (PTPs) with severe haemophilia A during standard prophylaxis for ≥6 months and ≥50 exposure days. Efficacy in treating bleeds and during surgical prophylaxis was also assessed. Results: Prophylactic efficacy, based on mean monthly bleeding rate, was rated as 'excellent' or 'good' in 97% of patients for all bleeds and in 100% of patients for spontaneous bleeds. Mean (SD) annualized bleeding rate was 2.28 (3.73) [median = 0.9] for all bleeds, 1.16 (2.57) [median = 0] for spontaneous bleeds and 1.00 (1.79) [median = 0] for traumatic bleeds. There were no bleeds in 50% of patients and there were no major, life-threatening bleeds. Efficacy was 'excellent' or 'good' in treating 28 (100%) of 28 bleeds. Overall efficacy was rated as 'excellent' during four surgical procedures (three major, one minor) and 'moderate' during one major surgery. Incremental in vivo recovery (IVR) data were comparable with the one-stage and chromogenic assays. IVR was >2.0% per IU kg À1 for all measurements and stable over 6 months. No patients developed FVIII inhibitors and there were no treatment-related serious or severe adverse events. Conclusion: These results in adult PTPs indicate that human-cl rhFVIII is effective for the prevention and treatment of bleeds in adults with severe haemophilia A.
The ultimate goal of treatment for patients with inhibitory antibodies should be to permanently eradicate the inhibitor by immune tolerance induction therapy (ITI). However, ITI procedures fail in a substantial number of patients and in many countries ITI is not even offered owing to its high cost. How patients with inhibitors are managed in different European countries is evaluated with a special focus on the use of by-passing agents, i.e. recombinant FVIIa (rFVIIa) and activated prothrombin complex concentrates (aPCC), as well as the type of monitoring performed. Investigators from 22 large haemophilia centres participating within the network of the European Haemophilia Therapy Standardisation Board (EHTSB) were asked to complete a questionnaire. rFVIIa was routinely used in all centres for both children and adults at dosages ranging from 90 to 250 mug kg(-1) at an interval of 2-4 h. aPCC was used in 85% of the centres in adults and in 25% of the centres in children with haemophilia A at dosages of 50-100 IU kg(-1) every 6-12 h. The corresponding figures for children and adults with haemophilia B were 40% and 15% of the centres, respectively. Higher dosages of both agents were considered in the case of life-threatening bleeds. General recommendations were developed, based on the information provided by the survey. The results clearly indicate the need for well-designed comparative studies to optimize the use of by-passing agents.
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