Pharmacokinetics and Safety of rFVIIIFc Manufactured at 15,000 L (15K) Scale

A Randomized, Open-Label Study to Evaluate the Pharmacokinetics and Safety of Recombinant Factor VIII Fc Fusion Protein (rFVIIIFc; BIIB031) Manufactured at 15K Scale and at Different Vial Strengths in Previously Treated Subjects With Severe Hemophilia A

The primary objective of the study is to compare the pharmacokinetic (PK) of recombinant coagulation factor VIII Fc fusion protein (rFVIIIFc) manufactured at the current scale of 2000 L (2K) to the PK of rFVIIIFc manufactured at the 15,000 L (15K) scale in previously treated participants with severe hemophilia A. The secondary objectives are: to characterize the PK of rFVIIIFc manufactured at the 15K scale at the 15K baseline and after 13 weeks of treatment; to characterize the PK of rFVIIIFc manufactured at the 15K scale at 1000 IU/vial and 6000 IU/vial strengths; and to evaluate the safety of rFVIIIFc manufactured at the 15K scale.

PK assessments are in 3 phases: Pharmacokinetic Assessment 1(PK1): PK assessments following single injection of rFVIIIFc manufactured at the 2K scale. Pharmacokinetic Assessment 2 (PK2): PK assessments are made following a single injection of rFVIIIFc manufactured at the 15K scale where participants are randomized to the 1000 IU vial or 6000 IU/vial strengths. Pharmacokinetic Assessment 3 (PK3): PK assessments are made following 13 weeks of rFVIIIFc treatment manufactured at the 15K scale where participants are randomized to the 1000 IU vial or 6000 IU/vial strengths. After study completion, in countries where rFVIIIFc is not commercially available, eligible participants will be offered enrollment into a long-term safety and efficacy extension study (8HA01EXT [NCT01454739]).

Key Inclusion Criteria:

• Have severe hemophilia A, defined as <1 IU/dL (<1%) endogenous FVIII as determined by one-stage clotting assay from the central laboratory at Screening.
• Previously treated subject, defined as having at least 150 documented prior exposure days (EDs) to any recombinant and/or plasma-derived FVIII and/or cryoprecipitate products at Day 1. Fresh frozen plasma treatment must not be considered in the count for documented exposure days.
• No history of a positive inhibitor test or clinical signs of decreased response to FVIII administrations. Family history of inhibitors will not exclude the subject.
• No measurable inhibitor activity using the Nijmegen-modified Bethesda assay (>=0.6 Bethesda Unit per milliliter [BU/mL] is considered positive) at Screening.

Key Exclusion Criteria:

• Current enrollment in any interventional clinical study in which an investigational drug or approved therapy for investigational use is administered within 30 days prior to the Baseline Visit OR prior participation in any of the following Biogen studies: 998HA101 (NCT01027377), 997HA301 (NCT01181128), 8HA02PED (NCT01458106), 997HA307 (NCT02083965), and 8HA01EXT (NCT01454739).
• Previous participation in this study.
• Any concurrent clinically significant major disease that, in the opinion of the Investigator or Biogen, makes the subject unsuitable for participation in the study.
• Other coagulation disorder(s) in addition to hemophilia A.
• History of hypersensitivity or anaphylaxis associated with FVIII or intravenous (IV) immunoglobulin administration.

NOTE: Other protocol-defined inclusion/exclusion criteria may apply.