Factor-VIII mimetic bispecific antibodies for the treatment of hemophilia A: an update

INTRODUCTION: Bispecific antibodies are used to treat various conditions, with notable results in hemophilia A, a rare bleeding disorder characterized by reduced or absent activity of the coagulation factor VIII (FVIII). Emicizumab is a bispecific antibody that mimics FVIII activity, reducing bleeds in people with hemophilia A (PwHA). The real-world effectiveness and safety profile of emicizumab stimulated the development of additional FVIII-mimetic antibodies. AREAS COVERED: This review covers recent progress in hemophilia A treatment, focusing on FVIII-mimetic bispecific antibodies. Emicizumab, the only currently approved FVIII-mimetic bispecific antibody, has shown effectiveness in reducing bleeding rates in PwHA with and without inhibitors, enabling improved musculoskeletal health and quality of life. Other FVIII-mimetic bispecific antibodies are in clinical trials (Mim8 and NXT007). We discuss mechanisms, preclinical and clinical outcomes, real-world data, safety, and new molecules expanding the therapeutic repertoire under development. EXPERT OPINION: The advent of FVIII-mimetic bispecific antibodies marks a shift in hemophilia A prophylaxis away from FVIII replacement therapies. Next-generation agents may offer enhanced activity and safety. Despite advances, challenges remain in monitoring activity, managing breakthrough bleeds, and understanding non-hemostatic FVIII roles. As long-acting, subcutaneous agents mature, they may redefine care, enabling personalized, safer, and more accessible prophylaxis across the lifespan.