Study Evaluating Prophylaxis Treatment & Characterizing Efficacy, Safety, & PK Of B-Domain Deleted Recombinant FVIII

Inclusion Criteria:

- Male subjects, aged less than 6 years, with moderately severe to severe hemophilia A.

- A negative FVIII inhibitor titer at screening, and a medical history negative for a
past FVIII inhibitor.

- At least 20 exposure days to any FVIII replacement product.

- Adequate hepatic and renal function

- CD4 count > 400 cells/uL, and if receiving antiviral therapy must be on a stable
regimen

Additional criteria for subjects participating in the PK assessment:

- Male subjects as described immediately above except they must have a FVIII Activity of
less than or equal to 1% confirmed by the central laboratory screening test

- Age < 6 years at time of PK assessment.

- The subject's size is sufficient to permit PK-related phlebotomy.

- The subject is able to comply with the procedures conducted during the PK assessment,
including a mandatory 72-hour washout period preceding the PK assessment.

Exclusion Criteria:

- A history of FVIII inhibitor.

- Presence of a bleeding disorder in addition to hemophilia A.

- Treatment with any investigational drug or device within 30 days before the time of
signing the informed consent form.

- Major or orthopedic surgery planned to occur during the course of the study.

- Regular (e.g., daily, every other day) use of antifibrinolytic agents or medications
known to influence platelet function such as aspirin or certain nonsteroidal
anti-inflammatory drugs (NSAIDs), or regular, concomitant therapy with
immunomodulating drugs (e.g., intravenous immunoglobulin [IVIG], routine systemic
corticosteroids).

- Known hypersensitivity to hamster protein.