This study is a single-arm, open-label study evaluating the safety and efficacy of GS1191-0445 injection as a single dose in Chinese subjects with severe hemophilia A.

GS1191-0445 is an adeno-associated virus 8 (AAV8)-delivered gene therapy designed to express B-domain deleted human factor VIII (FVIII) under the regulation of a human liver-specific promoter. Following a single intravenous administration, AAV8 gene expression cassette, which transfects hepatocytes and facilitates the specific expression and secretion of FVIII into the blood.

Inclusion Criteria:

1. Understand the purpose and risks of the study and provide informed consent in accordance with national and local privacy laws:
2. Subject must be male, aged ≥18 years old at the time of signing informed consent:
3. Participants with confirmed severe hemophilia A in their pre-admission history and based on clinical laboratory examination;
4. Subjects had used FVIII products for at least 150 exposure days (ED) before enrollment;
5. Subject has received continuous prophylactic treatment with exogenous FVIII for one year prior to enrollment or has been treated with exogenous FVIII on demand;
6. Subject has no history of hypersensitivity or allergic reactions related to the administration of FVIII agents;
7. Subject has no history of FVIII inhibitors.
8. Subjects agree to use a reliable barrier contraceptive method from the date of signing the informed consent
9. Subject is willing and able to follow planned visits, treatment plans, and other study procedures.

Exclusion Criteria:

1. The subject has any hemorrhagic disorder not related to hemophilia A,
2. Abnormal liver function test results of subjects during screening.
3. Abnormal laboratory examination of subjects during screening
4. The subject has acute or chronic hepatitis B virus (HBV) infection or chronic hepatitis C virus (HCV) infection; Or are receiving antiviral treatment for hepatitis B and C;
5. Active systemic immune disease.