Phase III, Open-label, Single-dose, Multi-center, Multinational Trial Investigating a Serotype 5 Adeno-associated Viral Vector Containing the Padua Variant of a Codon-optimized Human Factor IX Gene (AAV5-hFIXco-Padua, AMT-061) Administered to Adult Subjects With Severe or Moderately Severe Hemophilia B

AAV5-hFIXco-Padua

Factor IX (FIX)

Annualized Bleeding Rate (ABR) for All Bleeding Episodes

Factor IX Activity Levels After AMT-061 Dosing

Annualized Exogenous Factor IX Consumption

Adjusted Annualized Infusion Rate of FIX Replacement Therapy

Percent of Subjects Who Discontinued FIX Prophylaxis and Remained Free of Routine FIX Prophylaxis After AMT-061 Dosing

Percentage of Subjects With Trough FIX Activity <12% of Normal

ABR for FIX-treated Bleeding Episodes

Number of Spontaneous Bleeding Episodes

Number of Joint Bleeding Episodes

Mean FIX Activity (%) in Subjects With Pre-Existing Neutralizing Antibodies to AAV5 After AMT-061 Dosing

Mean FIX Activity (%) in Subjects Without Pre-Existing Neutralizing Antibodies to AAV5 After AMT-061 Dosing

Number of New Target Joints and the Number of New Target Joints Resolved.

Percent of Participants With Zero Bleeding Episodes During the 52 Weeks Following Stable FIX Expression (6 to 18 Months) After AMT-061 Dosing

International Physical Activity Questionnaire (iPAQ) Overall Score

EuroQol-5 Dimensions-5 Levels (EQ-5D-5L) VAS Overall Score

Number of Adverse Events