HOPE-B: Trial of AMT-061 in Severe or Moderately Severe Hemophilia B Patients

Inclusion Criteria:

1. Male

2. Age ≥18 years

3. Subjects with congenital hemophilia B, classified as severe or moderately severe, and
are currently on factor IX prophylaxis

4. >150 previous exposure days of treatment with factor IX protein

Exclusion Criteria:

1. History of factor IX inhibitors

2. Positive factor IX inhibitor test at screening

3. Select screening laboratory value >2 times upper limit of normal

4. Positive human immunodeficiency virus (HIV) test at screening, not controlled with
anti-viral therapy

5. Active infection with hepatitis B or C virus at screening

6. History of Hepatitis B or C exposure, currently controlled by antiviral therapy at the
end of the lead-in phase

7. Previous gene therapy treatment

8. Receipt of an experimental agent within 60 days prior to screening

9. Current participation or anticipated participation within one year after study drug
administration in this trial in any other interventional clinical trial involving
drugs or devices