Forum on: the role of recombinant factor VIII in children with severe haemophilia A.

The development of recombinant FVIII (rFVIII) products, fuelled by the need for improved safety of treatment arising from the dramatic widespread blood-borne virus transmission in the 1970-1980s revolutionized the care of children with haemophilia A over the last two decades. The larger availability of perceived safer replacement therapy associated with the introduction of rFVIII products reassured the haemophilia community and there was a strong push in some Western countries to treat haemophilic children only with rFVIII. Moreover, this significantly contributed in the 1990s to the diffusion outside Northern Europe of prophylactic regimens implemented at an early age to prevent bleeding and the resultant joint damage (i.e. primary prophylaxis), together with the possibility of home treatment. These changes led to a substantial improvement of the quality of life of haemophilic children and of their families. The general agreement that primary prophylaxis represents the first-choice treatment for haemophilic children has been recently supported by two randomized controlled trials carried out with rFVIII products, providing evidence on the efficacy of early prophylaxis over on-demand treatment in preserving joint health in haemophilic children. However, the intensity and optimal modalities of implementation of prophylaxis in children, in particular with respect to the issue of the venous access, are still debated. A number of studies also supports the role of secondary prophylaxis in children, frequently used in countries in which primary prophylaxis was introduced more recently. With viral safety now less than an issue and with the more widespread use of prophylaxis able to prevent arthropathy, the most challenging complication of replacement therapy for children with haemophilia remains the risk of inhibitor development. Despite conflicting data, there is no evidence that the type of FVIII concentrate significantly influences the complex multifactorial process leading to anti-FVIII alloantibodies, whereas other treatment-related factors are likely to increase (early intensive treatments due to surgery or severe bleeds) or reduce (prophylaxis) the risk. Although the optimal regimen is still uncertain, eradication of anti-FVIII antibodies by immune tolerance induction (ITI), usually with the same product administered at inhibitor detection, should be the first-choice treatment for all patients with recent onset inhibitors. This issue applies particularly to children, as most patients undergo ITI at an early age, when inhibitors usually appear. The availability of a stable and long-lasting venous access represents a leading problem also in this setting. These and other topics concerning rFVIII treatment of haemophilic children were discussed in a meeting held in Rome on 27 February 2008 and are summarized in this report.

Treatment with recombinant activated factor VII in a patient with hemophilia A and an inhibitor: advantages of administration by continuous infusion over bolus intermittent injections.

Recent studies have shown that treatment with a continuous infusion of recombinant activated factor VII (rFVIIa) is far more convenient than administration by bolus intermittent injections and may allow a substantial reduction in the dose. We present the case of a 26-year-old patient with hemophilia A, who had a high-titer inhibitor to both human and porcine factor VIII, and who had recently been admitted to hospital because of a bilateral severe ilio-psoas hematoma. Two subsequent courses of treatment with rFVIIa by bolus intermittent injection showed only a partial efficacy. A further administration of rFVIIa was therefore carried out using a continuous infusion regimen that proved to be fully efficacious. During the continuous infusion course levels of factor VII coagulant activity were in the range 18.2-5.2 U/ml, while the prothrombin time, expressed as an International Normalized Ratio, remained within the range 0.57-0.71. The continuous infusion, compared with the administration of the bolus intermittent infusion, reduced the amount of rFVIIa required by approximately 40-50%. Statistical analysis demonstrated that there was a strong positive correlation between the rate of infusion of rFVIIa and levels of factor VII coagulant activity (r = +0.941; P < 0.001), and a very significant negative correlation between levels of factor VII coagulant activity and prothrombin time values (r = -0.897; P < 0.001). In accordance with previous findings, our experience confirms that, when prolonged therapy is required, treatment with rFVIIa by continuous infusion is more convenient than administration of bolus intermittent injections, and may allow the saving of a large amount of drug. Moreover, we suggest potential additional advantages of the continuous infusion regimen over bolus intermittent injections, such as a better efficacy and a stronger correlation between prothrombin time and factor VII coagulant activity levels.