Liver-related aspects of gene therapy for hemophilia: need for collaborations with hepatologists

Adeno-associated virus-based gene therapies hemophilia allow long-term transgene expression with reduced annual bleeding rates. Various liver-related aspects are involved in the different phases of gene therapy, such as assessment of liver health in the pretherapy period, patient selection and follow-up, maintenance of liver health after gene therapy, and management of potential short- and long-term adverse events. Increase in alanine aminotransferease is a common adverse event that requires rapid evaluation and an immunosuppressive approach. It is therefore important that hemophilia treaters and hepatologists collaborate at all stages of gene therapy to assess potential safety issues and ensure the long-term success of gene therapy. Special attention should be given to patients with not well-defined conditions, e.g. patients with some degree of liver fibrosis or fatty liver disease, patients with a history of hepatitis C and hepatitis B infection, patients with HIV infection, and patients taking medications that may affect liver function.