Lead-in Study of VGB-R04 Gene Therapy for Hemophilia B-- An Observational Survey Analysis Study

Inclusion Criteria: 1. Male ≥18 years and ≤65years of age; 2. Confirmed diagnosis of hemophilia B (baseline FIX activity ≤ 2% of normal); 3. At least 50 days exposure history to FIX; 4. Currently receiving FIX Prophylaxis therapy or on-demand treatment to prevent bleeding; 5. Have acceptable laboratory values: 1. Hemoglobin ≥110 g/L; 2. Platelets ≥100×109 /L; 3. AST, ALT, alkaline phosphatase ≤2×upper limit of normal (ULN) at the testing laboratory; 4. Bilirubin ≤3× ULN ; 5. Creatinine ≤1.5× ULN. 6. No measurable factor IX inhibitor as assessed by the central laboratory and have no prior history of inhibitors to factor IX protein; Exclusion Criteria: 1. Have significant underlying liver disease within the past 6 months prior to or at Screening, including but not limited to: 1. Preexisting diagnosis of portal hypertension; 2. Splenomegaly; 3. Encephalopathy; 4. Reduction of serum albumin; 5. Evidence of significant liver fibrosis; 2. Have anti-VGB-R04 neutralizing antibody titers ≥1:5; 3. Evidence of severe infection disease, i.e., human immunodeficiency virus (HIV) infection, syphilis, tuberculosis, etc.; 4. Novel coronavirus infection occurred in the 6 weeks prior to entry into the group 5. Evidence of active hepatitis B virus infection (HBsAg positive) or hepatitis C virus infection (HCV-RNA positive); 6. Evidence of malignant tumours or those with a previous history of malignant tumours; 7. Have a history of chronic infection or other chronic diseases that the Investigator considers to constitute an unacceptable risk; 8. Any immunodeficiency; 9. planned surgery may be required within one year; 10. Past thromboembolic events (arterial or venous thromboembolic events); 11. Hypertensive patients with poor blood pressure control (systolic blood pressure ≥150 mmHg or diastolic blood pressure ≥90mmHg after antihypertensive drug treatment);