Gene Therapy Study in Severe Hemophilia A Patients With Antibodies Against AAV5

Inclusion Criteria: 1. Males ≥ 18 years of age with hemophilia A and residual FVIII levels ≤ 1 IU/dL as evidenced by medical history, at the time of signing the informed consent. 2. Detectable pre-existing antibodies against the AAV5 vector capsid as measured by AAV5 total antibody ELISA. 3. Subject must have been on prophylactic FVIII replacement therapy for at least 12 months prior to study entry. 4. No previous documented history of a detectable FVIII inhibitor, and results from a Bethesda assay or Bethesda assay with Nijmegen modification of less than 0.6 Bethesda Units (BU) (or less than 1.0 BU for laboratories with a historical lower sensitivity cutoff for inhibitor detection of 1.0 BU) on 2 consecutive occasions at least one week apart within the past 12 months (at least one of which should be tested at the central laboratory). 5. Sexually active participants must agree to use an acceptable method of effective contraception. Participants must agree to contraception use for at least 12 weeks post-infusion. Exclusion Criteria: 1. Any evidence of active infection including COVID-19, or any immunosuppressive disorder, except for HIV infection. HIV positive patients who meet all other eligibility criteria may be included if they have a CD4 count \> 200/mm3 and an undetectable viral load (unquantifiable viral load as defined as less than the limit of quantification by the testing laboratory's assay is permitted) while receiving an antiretroviral therapy (ART) regimen that does not contain efavirenz or another potentially hepatotoxic ART. 2. Evidence of liver dysfunction as assessed by liver tests and most recent, prior FibroScan or liver biopsy showing significant fibrosis of 3 or 4 as rated on a scale of 0-4 on the Batts-Ludwig (Batts 1995) or METAVIR (Bedossa 1996) scoring systems, or an equivalent grade of fibrosis if an alternative scale is used. 3. Chronic or active hepatitis B or C as evidenced by testing at screening. 4. Active malignancy, except non-melanoma skin cancer, or history of hepatic malignancy. 5. Any condition that, in the opinion of the investigator or Sponsor would prevent the patient from fully complying with the requirements of the study (including corticosteroid treatment and/or use of alternative immunosuppressive agents outlined in the protocol) and/or would impact or interfere with evaluation and interpretation of subject safety or efficacy result.