Hemophilia is a serious bleeding disorder characterized by repeated bleeding 
episodes into joints and muscles which can lead to permanent disabilities. 
Treatment with factor replacement therapy has proven to be effective at 
preventing these complications; however, it can lead to formation of 
neutralizing antibodies termed inhibitors which significantly complicate the 
management of the disorder. These inhibitor patients suffer from increased 
morbidity and mortality and there has been a major unmet need for novel 
therapeutic approaches. Recently, one such therapy, emicizumab, has been 
licensed in the United States. Areas covered: This manuscript contains a 
detailed discussion of the mechanism of action, the clinical trial development 
program as well as a review of the benefits and risks of this novel agent. In 
addition, practical considerations for the use of the agent are also described. 
Expert commentary: Emicizumab represents a new class of medication for the 
treatment of hemophilia A which in the past has relied on factor replacement 
therapy and bypassing agent (alternative factor) therapy. Emicizumab fulfills 
two major unmet needs in patients with hemophilia who have FVIII inhibitors. 
First, it provides for a much more effective therapy for the prevention of 
bleeding and second it substantially reduces the treatment burden.