1. The participant or legally authorized representative (in case of study participants <18 years of age) gave written informed consent to participate in the study.
2. Participant has hemophilia B.
3. Participant is defined as previously-treated patient (PTP):
- Participant aged ≥ 6 years that has been previously treated with plasma-derived and/or recombinant factor IX (FIX) concentrate(s) for a minimum of 150 exposure days (EDs).
- Participant aged < 6 years that has been previously treated with plasma-derived and/or recombinant FIX concentrate(s) for a minimum of 50 EDs.
4. Participant has no evidence of a history of FIX inhibitors.
5. Participant is human immunodeficiency virus negative (HIV-); or HIV+ with stable disease and CD4+ count ≥ 200 cells/mm^3, as confirmed by central laboratory at screening.
6. Participant is hepatitis C virus negative (HCV-) by antibody or PCR testing (if positive, antibody titer will be confirmed by polymerase chain reaction (PCR)), as confirmed by central laboratory at screening; or HCV+ with chronic stable hepatitis.
7. The participant is willing and able to comply with the requirements of the protocol.
1. Participant has known hypersensitivity or presence of any contraindication to RIXUBIS or its excipients including hamster protein.
2. Participant has evidence of an ongoing or recent thrombotic disease, fibrinolysis or disseminated intravascular coagulation (DIC).
3. Participant has a history of FIX inhibitors with a titer ≥ 0.6 Bethesda Units (BU) (as determined by the Nijmegen modification of the Bethesda assay or the assay, employed in the respective local laboratory) at any time prior to screening.
4. Participant has a detectable FIX inhibitor at screening, with a titer ≥ 0.6 BU as determined by the Nijmegen modification of the Bethesda assay in the central laboratory.
5. Participant has severe chronic liver disease as evidenced by, but not limited to, any of the following: International Normalized Ratio (INR) > 1.4 hypoalbuminemia, portal vein hypertension including presence of otherwise unexplained splenomegaly and history of esophageal varices.
6. Participant has severe chronic hepatic dysfunction [eg, ≥ 5 times upper limit of normal alanine aminotransferase (ALT), as confirmed by central laboratory at screening, or a documented INR > 1.5].
7. Participant has severe renal impairment (serum creatinine > 2.0 mg/dL), as confirmed by central laboratory at screening.
8. Participant has been diagnosed with an inherited or acquired hemostatic defect other than hemophilia B.
9. Participant’s platelet count is < 100,000/mL.
10. Participant has a clinically significant medical, psychiatric, or cognitive illness, or recreational drug/alcohol use that, in the opinion of the investigator, would affect participant’s safety or compliance.
11. Participant is currently receiving, or is scheduled to receive during the course of the study, an immunomodulating drug (eg, corticosteroid agents at a dose equivalent to hydrocortisone greater than 10 mg/day, or α-interferon) other than antiretroviral chemotherapy.
12. Participant has participated in another clinical study involving an investigational product (IP) or investigational device within 30 days prior to enrollment or is scheduled to participate in another clinical study involving an IP or investigational device during the course of this study.
13. Participant is a family member or employee of the investigator.