Novel coagulation factor concentrates: issues relating to their clinical implementation and pharmacokinetic assessment for optimal prophylaxis in haemophilia patients.

Prophylaxis is considered the optimal treatment regimen for patients with severe haemophilia, and may be especially important in the prevention of joint disease. Novel coagulation factor concentrates with prolonged half-lives promise to improve patient treatment by enabling prophylaxis with less frequent dosing. With the call to individualize therapy in haemophilia, there is growing awareness of the need to use pharmacokinetic (PK) assessments to tailor prophylaxis. However, for new factor concentrates, it is not yet known which PK values will be most informative for optimizing prophylaxis. This topic was explored at the Eighth Zurich Haemophilia Forum. On the basis of our clinical experience and a discussion of the literature, we report key issues relating to the PK assessment of new coagulation factors and include suggestions on the implementation of PK data to optimize therapy. As both inter- and intra-individual variability in factor half-life have been reported, we suggest that frequent PK assessments should be conducted. However, to diminish the burden of more frequent sampling, sparser sampling strategies and the use of population modelling should be considered. Guidelines on how to assay new factor concentrates, and which PK parameters should be measured, are needed. Concerns were raised regarding the possibility of breakthrough bleeding, and current thinking on how to prevent breakthrough bleeding may no longer be appropriate. Finally, as treatment adherence may be more important to ensure that a therapeutic level of a new coagulation factor concentrate is maintained, behavioural techniques could be implemented to help to improve treatment adherence.