A Study of BAX 888 in Male Adults With Severe Hemophilia A

Inclusion Criteria:

- Male, aged 18 to 75 years at the time of screening.

- Established severe hemophilia A (FVIII:C <1%, measured following >=5 days without
FVIII treatment) and/or documented intron 1 inversion or intron 22 inversion
mutation in the F8 gene, consistent with severe hemophilia A , and documented
evidence of >=3 hemorrhages over the previous 12 months requiring treatment with
exogenous FVIII or use of FVIII prophylaxis because of history of frequent bleeding
episodes.

- History of greater than (>) 150 exposure days to exogenously administered FVIII
concentrates or cryoprecipitate.

- Sexually active men must agree to use barrier contraception (combination of a condom
and spermicide) or limit sexual intercourse to post-menopausal, surgically
sterilized, or contraception-practicing partners for a minimum of 6 months after
administration of BAX 888, or until BAX 888 genomes are no longer detected in the
semen, whichever is sooner.

- Participant is willing and able to comply with the requirements of the protocol,
including provision of semen samples, maintenance of a diary of bleeding episodes
and FVIII protein use.

- Signed informed consent.

Exclusion Criteria:

- Bleeding disorder(s) other than hemophilia A.

- Personal laboratory evidence of having developed inhibitors to FVIII protein at any
time (>=0.6 Bethesda units [BU] on any single test).

- Documented prior allergic reaction to any FVIII product.

- Anti-Adeno-associated virus, serotype 8 (AAV8) neutralizing antibody titer >=1:5.
Participants whose laboratory assessments are less than or equal to (<=) 1:10 may be
re-tested within the same screening window and, if eligibility criterion is met on
retest, may be enrolled after confirmation by the Sponsor Medical Monitor.

- Known hypersensitivity to prednisolone or prednisone, or to any of the excipients.

- Having a disease in which treatment with prednisolone or prednisone is not tolerated
(including but not limited to osteoporosis with vertebral fractures, difficult to
control hypertension, and difficult to control diabetes).

- Evidence of markers of potential underlying risk for autoimmune mediated hepatic
disease:

- Anti-smooth muscle antibody assay results >=40 (Inova QUANTA LiteTM Actin IgG
enzyme-linked immunosorbent assay [ELISA]); values of 31 to 39 will be flagged
as possibly abnormal and the Investigator and Medical Monitor will evaluate the
participant for eligibility.

- Elevated anti-liver-kidney microsomal antibody type 1 (LKM1) titers.

- Total immunoglobulin G (IgG) >1.5*upper limit of normal (ULN).

- Antinuclear antibody (ANA) titer >1:320; OR ANA titer >1:80 if demonstrated
concurrently with alanine aminotransferase (ALT) that is >ULN.

- Active Hepatitis virus (Hepatitis C): As indicated by detectable hepatitis C virus
(HCV) ribonucleic acid (RNA) by polymerase chain reaction (PCR).

- Hepatitis B: If surface antigen is positive.

- Seropositive for Human Immunodeficiency Virus (HIV).

- Receiving systemic antiviral and/or interferon therapy within 4 weeks prior to
enrollment.

- Clinically significant infections (e.g. systemic fungal infections) requiring
systemic treatment.

- Known immune disorder (including myeloma and lymphoma).

- Concurrent chemotherapy or biological therapy for treatment of neoplastic disease or
other disorders.

- An absolute neutrophil count <1000 cells per cubic millimeter (cells/mm^3).

- Markers of hepatic inflammation or cirrhosis as evidenced by 1 or more of the
following:

- Platelet count of <150,000/microliter (mcL).

- Serum albumin level is below the central laboratory's lower limit of normal and
FibroSURE is >=0.48 (i.e., Metavir staging of F2 or greater). Of note, in
participants with a known history of Gilbert's syndrome, a Fibrotest cannot be
used for fibrosis testing.

- Total bilirubin >1.5*ULN and direct bilirubin >=0.5 milligram per deciliter
(mg/dL).

- ALT or aspartate aminotransferase (AST) >1.0*ULN.

- Alkaline phosphatase (AP) >2.0*ULN.

- History of liver biopsy indicating moderate or severe fibrosis (Metavir staging
of F2 or greater).

- History of ascites, varices, variceal hemorrhage, or hepatic encephalopathy.

- Any findings on screening ultrasound that would preclude the safe use of AAV
gene therapy.

- Prothrombin time (PT) international normalized ratio (INR) >=1.4.

- Serum creatinine >1.5 mg/dL.

- Urine protein >30 mg/dL or >0.5 gram per day (g/day).

- Body mass index >38.

- Major surgery or an orthopedic surgical procedure planned within 6 months after
enrollment.

- Acute or chronic disease that, in the opinion of the investigator, would adversely
affect participant safety or compliance or interpretation of study results.

- Received an AAV vector previously or any other gene transfer agent in the previous
12 months prior to Study Day 0.

- Received an investigational intervention or participated in another clinical trial
within 4 weeks prior to enrollment or within 5 half-lives of the investigational
drug administration, whichever is longer.

- Significant cardiovascular disease (such as New York Heart Association Class III or
IV cardiac disease, congestive heart failure, myocardial infarction within the
previous 6 months, unstable arrhythmias, or unstable angina) or significant
pulmonary disease (including obstructive pulmonary disease).

- Recent history of psychiatric illness or cognitive dysfunction (including drug or
alcohol abuse) that in the opinion of the investigator, is likely to impair
participants ability to comply with protocol mandated procedures.

- Participant is a family member or employee of the investigator.