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

Inclusion Criteria:

1. 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
2. Age below or equal to 12 years (until patient turns 13 years, at time of inclusion)
3. Body weight above or equal to 10 kg
4. History of at least 50 exposure days (EDs) to other FIX products
5. 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:

1. Known history of FIX inhibitors
2. Current FIX inhibitors above or equal to 0.6 Bethesda Units (BU)
3. Congenital or acquired coagulation disorder other than haemophilia B
4. Platelet count below 50,000/mcL at screening
5. Alanine aminotransferase (ALT) above 3 times the upper limit of normal reference ranges at screening
6. Creatinine level above or equal to 1.5 times above the upper normal limit of normal reference ranges at screening
7. Human immunodeficiency virus (HIV) positive, defined by medical records, and with a CD4+ lymphocyte count below or equal to 200/mcL
8. Immune modulating or chemotherapeutic medication (except single pulse treatment, inhaled and topical steroids)
9. Previous arterial thrombotic events (myocardial infarction and intracranial thrombosis, as defined by medical records)