Hemophilia Inhibitor Previously Untreated Patient Study

Hemophilia A is a congenital bleeding disorder caused by deficiency of factor VIII (FVIII)
and is treated by replacement therapy with FVIII concentrate. Approximately 30% of people
with severe hemophilia A develop neutralizing antibodies, called FVIII inhibitors, which
interfere with the function of FVIII concentrates. The reason that some, but not all, people
with severe hemophilia A develop inhibitors is incompletely understood. Understanding
individual and environmental risk factors is important to be able to prevent and possibly
treat inhibitors. This study will look at individual and treatment characteristics in babies
with severe hemophilia A who have not yet received treatment with FVIII (called Previously
Untreated Patients, or PUPS). Subjects in the study will be asked to provide diaries of
treatments, medications, and illnesses. Treatment will be directed by the subjects'
physician, but all subjects will receive Advate, a third-generation recombinant FVIII
product. Subjects will have blood drawn for laboratory tests, which include studies of the
immune system and genetic studies of the FVIII mutation, before and 7-9 days after the first
treatment with FVIII, and 5 days (+/-2 days) after the 5th, 10th, 20th, 30th, 40th, and 50th
days of treatment with FVIII (exposure days). The duration of the study will be first 50
treatments or 3 years, whichever comes first.