BAX 855 PK-guided Dosing

INCLUSION CRITERIA:

- Participants transitioning from another BAX 855 study who meet ALL of the following
criteria are eligible for this study:

1. Participant has completed the end of study visit of a BAX 855 study or is
transitioning from the ongoing Baxalta Continuation Study 261302.

2. Participant is either receiving on-demand treatment or prophylactic treatment
with BAX 855 and had an Annual Bleed Rate (ABR) of ≥ 2 documented and treated
during the past 12 months.

3. Participant is human immunodeficiency virus negative (HIV-); or HIV+ with stable
disease and CD4+ count ≥ 200 cells/mm^3, as confirmed by central laboratory.

4. Participant is willing and able to comply with the requirements of the protocol.

- Newly recruited participants (ie not transitioning from another BAX 855 study)
including BAX855 naïve participants who meet ALL of the following criteria are
eligible for this study:

1. Participant has severe hemophilia A (FVIII clotting activity < 1%) as confirmed
by central laboratory OR by historically documented FVIII clotting activity
performed by a certified clinical laboratory, optionally supported by a FVIII
gene mutation consistent with severe hemophilia A

2. Participant has been previously treated with plasma-derived FVIII concentrates or
recombinant FVIII for ≥ 150 documented exposure days (EDs)

3. Participant is either receiving on-demand treatment or prophylactic treatment and
had an annual bleeding rate of ≥ 2 documented and treated during the past 12
months.

4. Participant has a Karnofsky performance score of ≥ 60 at screening

5. Participant is HIV-; or HIV+ with stable disease and CD4+ count ≥ 200 cells/mm^3,
as confirmed by central laboratory at screening

6. Participant is hepatitis C virus negative (HCV-) by antibody (if positive,
additional PCR testing will be performed), as confirmed by central laboratory at
screening; or HCV+ with chronic stable hepatitis

7. If female of childbearing potential, participant presents with a negative urine
pregnancy test and agrees to employ adequate birth control measures for the
duration of the study

8. Participant is willing and able to comply with the requirements of the protocol.

EXCLUSION CRITERIA:

- Participants transitioning from another BAX 855 study who meet ANY of the following
criteria are not eligible for this study:

1. Participant has developed a confirmed inhibitory antibody to FVIII with a titer
of ≥ 0.6 BU using the Nijmegen modification of the Bethesda assay as determined
at the central laboratory during the course of the previous BAX 855 study.

2. Participant has been diagnosed with an acquired hemostatic defect other than
hemophilia A.

3. The participant's weight is < 35 kg or > 100 kg.

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

5. Participant has an abnormal renal function (serum creatinine > 1.5 times the
upper limit of normal).

6. Participant has active hepatic disease with alanine aminotransferase (ALT) and/or
aspartate aminotransferase (AST) levels ≥ 5 times the upper limit of normal.

7. Participant is scheduled to receive 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 during the
study.

8. Participant has a clinically significant medical, psychiatric, or cognitive
illness, or recreational drug/alcohol use that, in the opinion of the
investigator, would affect participant's safety or compliance.

9. Participant is planning to take part in any other clinical study during the
course of the study.

10. Participant is 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.

Newly recruited participants (ie not transitioning from another BAX 855 study) who meet ANY
of the following criteria are not eligible for this study:

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 confirmed FVIII inhibitors with a titer ≥ 0.6 Bethesda
Units (BU) (as determined by the Nijmegen modification of the Bethesda assay or the
assay employed with the respective cut-off in the local laboratory) 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. The participant's weight is < 35 kg or > 100 kg.

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

6. Participant has known hypersensitivity towards mouse or hamster proteins, PEG or Tween
80.

7. Participant has severe chronic hepatic dysfunction [eg, ≥ 5 times upper limit of
normal alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST), as
confirmed by central laboratory at screening, or a documented INR > 1.5].

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

9. 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.

10. 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.

11. Participant has participated in another clinical study involving an 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.

12. Participant 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.

13. Participant is 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.