Patients: 74 male patients aged 13 to 70 years with hemophilia B. Patients had FIX activity ≤2 IU/dL, no history of inhibitors to FIX, and at least 150 exposure days to any FIX product.
Study design: Patients were selected for prophylaxis or on-demand treatment at screening. On-demand patients participated in the trial for 28 weeks and received a single dose of 40 IU/kg for bleeding episodes (80 IU/kg for severe bleeding episodes). Prophylaxis patients participated for 52 weeks. Prophylaxis patients were randomly divided into groups of 10 IU/kg once weekly and 40 IU/kg once weekly. Patients were blinded to the prophylaxis dose. The investigator was blinded but could become unblinded if it became necessary to measure a patient’s FIX activity. A pharmacokinetic assessment of the two prophylactic doses was conducted using a subset of these patients. Pharmacokinetic assessments were based on a 1-stage clotting assay and performed at trial initiation (single dose assessments) and after 12 to 44 weeks of prophylaxis (steady state assessments) with both trial doses. The assessments included 7 sampling points up to 168 hours post injection.
Primary endpoint: Safety of Rebinyn®, measured by factors including development of FIX inhibitors (per Nijmegan modified Bethesda assay), adverse events, noninhibitory binding antibodies against Rebinyn®, and antibodies against host cell proteins.
Secondary endpoints: Efficacy and prophylactic effect of Rebinyn® when treating spontaneous or traumatic bleeding episodes. Assessment included number of doses, amount of product used, duration of bleed, and annual bleed rate.