Dose Confirmation Trial of AAV5-hFIXco-Padua

Phase IIb, Open-label, Single-dose, Single-arm, Multi-center Trial to Confirm the Factor IX Activity Level of the 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

This is an open-label, single-dose, single-arm, multi-center trial, with a screening, a treatment + post-treatment follow-up phase, and a long-term follow-up phase.

The IMP AMT-061 is a recombinant adeno-associated viral vector of serotype 5 (AAV5) containing the Padua variant of a codon-optimized human FIX complementary deoxyribonucleic acid (cDNA) under the control of a liver-specific promoter. The IMP is identified as AAV5-hFIXco-Padua (AMT- 061). The pharmaceutical form of AMT-061 is a solution for intravenous infusion.

The administered dose of AMT-061 will be 2 x 10^13 gc/kg.

Inclusion Criteria:

1. Male
2. Age ≥18 years
3. Subjects with congenital hemophilia B classified as severe or moderately severe
4. >20 previous exposure days of treatment with FIX protein

Exclusion Criteria:

1. History of FIX inhibitors
2. Positive FIX inhibitor test at screening
3. Select screening laboratory values > 2 times upper normal limit:
4. Positive human immunodeficiency virus (HIV) 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