Long-term safety of treatment of hemophilia A: a comprehensive review

INTRODUCTION: Hemophilia A is an inherited bleeding disorder due to factor VIII (FVIII) deficiency and is characterized by recurrent bleeding and progressive joint damage. For the last two decades, treatment strategies have expanded from FVIII replacement therapy to include extended half-life products, non-factor therapies, rebalancing agents, and gene therapy. These advances have improved clinical outcomes but also introduced long-term safety considerations that require careful evaluation. AREAS COVERED: This review summarizes long-term safety data across the current therapeutic landscape for hemophilia A. Evidence from pivotal clinical trials, extension studies, real-world registries, and recent international congress reports was evaluated to assess the safety profiles of standard- and extended-half-life FVIII concentrates, efanesoctocog alfa, non-factor therapies such as emicizumab, emerging rebalancing agents targeting natural anticoagulant pathways, and adeno-associated viral vector-based gene therapies. EXPERT OPINION: Hemophilia A therapies demonstrate generally favorable long-term safety profiles for established treatments and have markedly reduced treatment burden, although mature long-term safety data remain limited for the most recently introduced agents. Inhibitor development remains the principal complication of FVIII replacement therapy, whereas non-factor and rebalancing therapies pose potential thrombotic risks that require careful monitoring. Gene therapy offers durable FVIII expression after a single administration but raises concerns about hepatotoxicity, expression durability, and long-term safety. Ongoing pharmacovigilance and individualized treatment selection remain essential as therapeutic options continue to expand.