Exploratory in vitro evaluation of thrombin generation of eptacog beta (recombinant human fviia) and emicizumab in congenital haemophilia A plasma.

INTRODUCTION/AIM: Eptacog beta is a recombinant activated human factor VII approved to treat and control bleeding in haemophilia A and B patients with inhibitors. Emicizumab is a factor VIIIa mimetic antibody approved for prophylactic treatment of haemophilia A with and without inhibitors (HAI and HA, respectively). Inhibitor patients treated with emicizumab should expect breakthrough bleeding that requires bypassing agent treatment to restore haemostasis. The aim of this study is to quantify the in vitro thrombin generation induced by the addition of eptacog beta to HAI and HA plasma containing emicizumab. METHODS: Thrombin generation assays were performed using HAI and HA plasma. Thrombin generation parameters were examined using a fixed effects model with inhibitor titre, eptacog beta concentration and emicizumab concentration as main effects, and eptacog beta concentration with inhibitor and emicizumab concentration with inhibitor as interaction effects. RESULTS: A significant increase in peak thrombin, ETP and velocity was observed when combinations of eptacog beta (0, 1, 2 or 5 µg/ml) and emicizumab (0, 50 or 100 µg/ml) were evaluated in HA and HAI plasma; the effect remained below that observed in Normal Plasma (NP). A small shortening of lag time below that of NP was observed. CONCLUSIONS: Eptacog beta and emicizumab induced thrombin generation in haemophilia A plasma (with and without inhibitors) with the thrombin generation parameters remaining below those of normal plasma. These data provide in vitro proof of concept supporting the concept of use of eptacog beta for the treatment and control of breakthrough bleeding in patients on emicizumab prophylaxis.

Comparison of antioxidant properties of different therapeutic albumin preparations.

Albumin displays several important functions for homeostasis amongst which the maintenance of the plasma redox-state. The study aim was to compare the redox state of pharmaceutical human albumin preparations since it reflects the oxidation-reduction status of the surrounding environment. Using an array of analytical methods, four commercially available albumins were compared with respect to their structural characteristics (cobalt ion binding, glycation, spectrophotometric and fluorometric profiles) and their ability to scavenge hydroxyl, peroxyl or free radicals. The different albumins exhibited a similar structural profile as well as hydroxyl and peroxyl scavenging activities. By contrast, the albumin from LFB (Vialebex(®)) possessed a significantly higher capacity to transfer electrons to DPPH, as compared with other albumins that was correlated with the level of free cysteine-34. Commercially available albumins differed for some of their antioxidant properties. The albumin preparation possessing the highest level of free cysteine-34 exhibited the highest antioxidant potential.