Hemophilia B is a genetic bleeding disorder caused by pathogenic variants (eg, mutations, deletion) in the FIX gene. HB patients have frequent and potentially life-threatening bleeding and often develop progressive physical disability and pain from chronic haemarthropathy. Current replacement therapy needs regular treatment in the life-long time, bringing heavy economic and social burdens.~VGB-R04 is a novel AAV vector carrying a high specific activity factor IX variant. This study is intended to evaluate the safety, tolerability and efficacy of a single IV infusion of VGB-R04. All subjects in this study will provide informed consent and then undergo screening assessments up to 6 weeks before administration of VGB-R04. All subjects will undergo 52 weeks of safety observation and will be encouraged to enroll in an Long-term follow-up study to evaluate the long-term safety of VGB-R04 for a total of five years.
A multicenter, open, non-randomized, phase I/II, two-phase clinical study. The dose exploration phase was phase I, and the dose extension phase was phase II.