• Participants with a diagnosis of severe hemophilia A or B
Participants who are enrolled into the Non-Inhibitor Cohort must also meet the following
- No detectable or documented history of inhibitors
- Participants outside the US and Canada with FVIII/FIX replacement, and willing to
continue to receive routine prophylaxis treatment with FVIII/FIX replacement during
the Observational Phase. Participants in the US and Canada receiving routine
prophylaxis treatment not eligible to be enrolled.
- Participants with on-demand treatment regimen with ≥6 acute bleeding episodes
(spontaneous and/or traumatic) that required coagulation factor infusion during the 6
months period prior to Screening and willing to continue to receive on demand
treatment during the Observational Phase.
Participants who are enrolled into the Inhibitor Cohort must also meet the following
- Documentation of current high titer inhibitor (≥5 BU/mL) or current low titer
inhibitor ( recovery Phase
- Participants with on-demand treatment regimen with ≥6 bleeding episodes (spontaneous
and/or traumatic) necessitating treatment with bypass factor for at least 6 months
prior to screening and willing to continue to receive on-demand treatment during the
- Previous or current treatment for and/or history of coronary artery diseases, venous
or arterial thrombosis or ischemic disease
- Known planned surgical procedure during the planned study period.
- Known hemostatic defect other than hemophilia A or B.
- Abnormal renal or hepatic function
- Current unstable liver or biliary disease
- Abnormal hematologic parameters
- Abnormal coagulation activity
- Other acute or chronic medical or psychiatric condition or laboratory abnormality that
may increase the risk associated with study participation or investigational product
administration or may interfere with the interpretation of study results and, in the
judgment of the investigator,
- Current routine prophylaxis with bypassing agent
- Regular, concomitant therapy with immunomodulatory drugs
- Ongoing or planned use of immune tolerance induction or prophylaxis with FVIII or FIX
replacement during the Active Treatment Phase.
- Participation in other studies involving investigational drug(s) within 30 days (or as
determined by local requirements) or 5 half-lives prior to study entry and/or during
- CD4 cell count ?200/uL if human immunodeficiency virus (HIV)-positive
- Clinically relevant ECG abnormalities that may affect participant safety or
interpretation of study results.
- Investigator site staff members directly involved in the conduct of the study and
their family members, site staff members otherwise supervised by the investigator, or
participants who are Pfizer employees, including their family members, directly
involved in the conduct of the study.