INdividualized ITI Based on Fviii(ATE) Protection by VWF

Participants will be randomized on a one-to-one basis between one of two study arms,
individualized lot selection (alternative treatment arm) and random lot selection (standard
treatment arm, current US clinical practice in ITI). Study sites, participants, and
investigators will be blinded to the treatment status assigned.

Alternative treatment arm:

Half of the participants will be randomized to blinded individualized lot selection for ITI.
The target initial dose of FVIII for ITI is ~200 IU/kg/day intravenously. The suggested
maximum dose is 20,000 IU/day. Investigators may adjust the dose to a minimum dose of 150
units/kg if infusion volume is not feasible in patients without central venous access or in
patients with von Willebrand factor levels >250%. Splitting dose into two infusions per day
must be approved by the Steering Committee, and if approved, will be considered a protocol
deviation. Wilate® will be the VWF/FVIII complex concentrate (Octapharma USA, Inc., U.S.
License No. 1646) prescribed for ITI.

Individualized lot selection will be performed according to a modified Oxford method in a
central laboratory, by testing subject's plasma against 4-6 lots of Wilate® and selecting the
one with the highest residual FVIII (lowest Oxford titer) activity remaining after
incubation. The same lot will be used throughout the entire ITI course for each subject. If
the selected lot is depleted prior to the completion of ITI, a second individualized lot
selection will be performed using the original plasma sample provided at baseline.

Each Wilate® batch includes 1.6-1.8 million IU and is expected to last for about 3-57 months
depending on the weight of the subject and prescribed dose.

Standard treatment arm:

The other half of the participants will receive random lot selection for ITI. The dose and
concentrate used will be the same. Concentrate will be randomly selected from available
Wilate® lots. The same lot will be used throughout the entire ITI course for each subject. If
the random lot is depleted prior to the completion of ITI, a second lot will be randomly
selected. In both cases the random lot will be tested against subject's plasma to measure the
residual FVIII activity left after incubation but this result will not affect lot selection.

The primary hypothesis is that the time to negative inhibitor (<0.6 BU) will be shorter with
individualized lot selection compared to random lot selection and that this will impact
monthly break-through bleeding and reduce costs.

Inclusion Criteria:

1. Diagnosis of congenital Hemophilia A and baseline FVIII ≤2%.

2. Weight ≥ 5 kg

3. History of FVIII inhibitor titer ≥5 BU

4. Current FVIII inhibitor titer ≥5 BU or ≥0.6 BU and failed ITI defined by FVIII
recovery <66% normal and half-life <6 hours

5. Adequate venous access for daily concentrate infusions

6. For participants <18 years, a parent or guardian willing and able to provide informed
consent with verbal or written assent from the child if require by the local
institution. For participants ≥18 years, a willingness and ability to provide informed
consent from the subject.

7. Ability to comply with study related treatments, evaluations, and follow-up.

Exclusion Criteria:

1. Acquired hemophilia

2. Congenital or acquired bleeding disorder in addition to Hemophilia A

3. ITI factor replacement regimen within the past one month unless there is clear
evidence of ITI failure with no reduction in inhibitor titer over the past two months

4. HIV positive with viral load ≥200 particles/μL or ≥400,000 copies/mL

5. Rituximab within the past 3 months

6. IVIG within the past 1 month

7. Treatment with other immunosuppressive drugs within the past 1 month (excluding
intermittent steroid use for asthma)

8. Concomitant experimental treatment

9. History of hypersensitivity to plasma-derived VWF- or FVIII-containing concentrates

10. Elective surgery planned in the next 6 months (excluding vascular access procedure)

11. Any condition or chronic illness, which in the opinion of the investigator makes
participation ill-advised

12. Inability or unwillingness to complete required screening, follow-up, and exit studies