BAX 855 Previously Untreated Patient (PUP)

Inclusion Criteria

1. Participant is < 6 years old at the time of screening

2. Participant is previously untreated with < 3 exposure days (EDs) to ADVATE, BAX 855 or
plasma transfusion at any time prior to screening

3. Participant has severe hemophilia A (Factor VIII (FVIII) < 1%) as determined by the
central laboratory, or a historical FVIII level < 1% as determined at any local
laboratory, optionally supported by an additional FVIII gene mutation consistent with
severe hemophilia A

4. Participant is immune competent with a CD4+ count > 200 cells/mm^3, as confirmed by
the central laboratory at screening

5. Parent or legally authorized representative is willing and able to comply with the
requirements of the protocol

Additional inclusion criteria for Part B (immune tolerance induction (ITI))

1. Parent or legal representative has/have voluntarily provided signed informed consent
for ITI portion

2. Participant has a confirmed positive high titer inhibitor (> 5.00 Bethesda unit (BU))
or has a positive confirmed low titer inhibitor (≥ 0.6 BU) as determined by the
central laboratory based on a second repeat blood sample with

1. poorly controlled bleeding despite increased BAX 855 doses, or

2. requires bypassing agents to treat bleeding

Exclusion Criteria

1. Participant has detectable FVIII inhibitory antibodies (≥ 0.6 BU using the Nijmegen
modification of the Bethesda assay) as confirmed by central laboratory at screening

2. Participant has a history of FVIII inhibitory antibodies (≥ 0.6 BU using the Nijmegen
modification of the Bethesda assay or the Bethesda assay) at any time prior to
screening

3. Participant has been diagnosed with an inherited or acquired hemostatic defect other
than hemophilia A (eg, qualitative platelet defect or von Willebrand's disease)

4. Participant has been previously treated with any type of FVIII concentrate other than
ADVATE or BAX 855, or was administered ADVATE, BAX 855 or plasma transfusion for ≥ 3
EDs at any time prior to screening

5. Participant receives >2 EDs of ADVATE in total during the periods prior to enrollment
and during the screening period, until the baseline infusion.

6. The participant's weight is anticipated to be < 5 kg at the baseline visit

7. Participant's platelet count is < 100,000/mL

8. Participant has known hypersensitivity towards mouse or hamster proteins, polyethylene
glycol (PEG) or Tween 80

9. Participant has severe chronic hepatic dysfunction [eg, > 5 times upper limit of
normal alanine aminotransferase (ALT), aspartate aminotransferase (AST), or a
documented international normalized ratio (INR) > 1.5] in his medical history or at
the time of screening

10. Participant has severe renal impairment (serum creatinine > 1.5 times the upper limit
of normal)

11. Participant has current or recent (< 30 days) use of other PEGylated drugs prior to
study participation or is scheduled to use such drugs during study participation

12. Participant is scheduled to receive during the course of the study a systemic
immunomodulating drug (e.g. corticosteroid agents at a dose equivalent to
hydrocortisone greater than 10 mg/day or α-interferon) other than anti-retroviral
chemotherapy

13. 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

14. Parent or legally authorized representative has a medical, psychiatric, or cognitive
illness or recreational drug/alcohol use that, in the opinion of the investigator,
would affect participant safety or compliance

15. Parent, legally authorized representative or participant are a member of the team
conducting this study or is in a dependent relationship with one of the study team
members. Dependent relationships include close relatives (ie, children,
partner/spouse, siblings, parents) as well as employees of the investigator or site
personnel conducting the study.

Additional exclusion criteria for Part B (ITI)

1. Spontaneous disappearance of the inhibitor prior to ITI

2. FVIII inhibitor titer ≥ 0.6 BU is not confirmed by a second new blood sample and
determined at the central laboratory

3. Inability or unwillingness to comply with the protocol