BACKGROUND BAY 81-8973 is a full-length, unmodified, recombinant human factor VIII (FVIII) for the treatment of hemophilia A. OBJECTIVE The aim of this study was to compare the pharmacokinetic (PK) profile of BAY 81-8973 with antihemophilic factor (recombinant) plasma/albumin-free method (rAHF-PFM) PATIENTS/METHODS In this phase I, open-label, crossover study, men aged 18-65 years with severe hemophilia A and ≥150 exposure
days to FVIII were randomized to receive a single intravenous infusion of 50 IU/kg BAY 81-8973 or rAHF-PFM, followed by crossover to a single infusion of the other treatment. FVIII levels were measured in plasma over 48 h using one-stage and chromogenic assays. PK parameters, including area under the curve from time zero to the last data point (AUClast; primary outcome) and half-life (t (1/2)) were calculated. A population PK model was developed to simulate various treatment scenarios. RESULTS Eighteen patients were randomized and analyzed. Using both assays, geometric mean (coefficient of variation [%CV]) AUClast was significantly higher, and t (1/2) was significantly longer, for BAY 81-8973 versus rAHF-PFM (one-stage, AUClast: 1660 IU.h/dL [29.4] vs. 1310 IU.h/dL [29.0], p < 0.0001; one-stage, t (1/2): 14.5 [25.7] vs. 11.7 h [27.3], p < 0.0001). Simulations showed that median time to 1 IU/dL was approximately 27% longer for BAY 81-8973 versus rAHF-PFM over doses of 25-50 IU/kg; plasma levels >1 IU/dL could be maintained with 14.4 IU/kg BAY 81-8973 or 39.1 IU/kg rAHF-PFM 3x/week. CONCLUSIONS BAY 81-8973 showed a superior PK profile versus rAHF-PFM. The same FVIII trough threshold level could be achieved with lower doses of BAY 81-8973 versus rAHF-PFM. ClinicalTrials.gov: NCT02483208.