Safety, Efficacy and Pharmacokinetics of NNC-0156-0000-0009 in Previously Treated Children With Haemophilia B.

Inclusion Criteria:

- Male patients with moderately severe or severe congenital haemophilia B with a Factor
IX activity level below or equal to 2% according to medical records

- Age below or equal to 12 years (until patient turns 13 years, at time of inclusion)

- Body weight above or equal to 10 kg

- History of at least 50 exposure days (EDs) to other FIX products

- The patient and/or parent(s)/caregiver are capable of assessing a bleeding episode,
keeping an electronic diary (eDiary), capable of conducting home treatment and
otherwise able to follow trial procedures

Exclusion Criteria:

- Known history of FIX inhibitors

- Current FIX inhibitors above or equal to 0.6 Bethesda Units (BU)

- Congenital or acquired coagulation disorder other than haemophilia B

- Platelet count below 50,000/mcL at screening

- Alanine aminotransferase (ALT) above 3 times the upper limit of normal reference
ranges at screening

- Creatinine level above or equal to 1.5 times above the upper normal limit of normal
reference ranges at screening

- Human immunodeficiency virus (HIV) positive, defined by medical records, and with a
CD4+ lymphocyte count below or equal to 200/mcL

- Immune modulating or chemotherapeutic medication (except single pulse treatment,
inhaled and topical steroids)

- Previous arterial thrombotic events (myocardial infarction and intracranial
thrombosis, as defined by medical records)