Views on methods for monitoring recombinant factor VIIa in inhibitor patients

The development of recombinant factor VIIa (rFVIIa) has greatly augmented the range of treatment options available for hemophilia patients with inhibitors. However, there still remains a lack of consensus regarding several aspects of treatment with bypassing agents such as rFVIIa, prothrombin complex concentrates (PCC), and activated PCC (aPCC). Such unresolved issues may be clarified by the identification of a suitable laboratory monitoring method with which to correlate clinical outcomes. This paper will review the need for an effective and informative monitoring strategy, and will discuss several candidate methods that have been employed for the measurement of hemostatic efficacy following therapy with bypassing agents. To date, however, no assay endpoint has been developed that can correlate accurately with clinical outcomes in a sufficiently large patient sample.