F8 and hemophilia A: Antihemophilic Factor (Recombinant), Fc Fusion Protein is a marketed FVIII product for the treatment of hemophilia A. Prior in vitro studies have demonstrated that the recombinant Factor VIII-Fc fusion protein (rFVIIIFc) interacts with high-affinity and low-affinity Fc gamma receptors (FcγR) expressed by different immune cell populations (9–13).