The main aim of this study is to learn about changes in the lowest blood levels of Factor VIII in men and boys when upgraded from standard prophylaxis with Advate to individualized prophylaxis with Advate.

No study medicines will be provided to participants in this study. The study sponsor will not be involved in how participants are treated but will provide instructions on how the clinics will record what happens during the study. Participants will need to visit the study doctor 3 times in total during the study. During these visits, study data will be collected by the study doctor.

Local, Multicenter, Non-interventional, Ambispective Study in Severe Hemophilia A Patients on Standard and PK-tailored Prophylaxis With Octocog Alfa (Advate®) in the Russian Federation

Inclusion Criteria:

• Male participants of all ages with severe hemophilia A (FVIII ˂1%) or moderate hemophilia A with severe bleeding phenotype who:

  • had been on standard prophylaxis or PK-tailored prophylaxis with octocog alfa during at least 12 months prior to the study enrollment (150 participants) or who started Advate® treatment in 2021 (20 participants),
  • is being treated with octocog alfa at the moment of enrolment with any of the above mentioned treatment modalities, and
  • had been assigned octocog alfa provision in Federal reimbursement program 2021

• Availability of participants' records sufficient for data collection according to the study objectives during the retrospective period of the study for participants who had been on standard prophylaxis or PK-tailored prophylaxis with octocog alfa during at least 12 months prior to the study enrollment

• Written informed consent provided by the participant or, in case of children below 14 years of age, by participant's parent or participant's legally acceptable representative.

Exclusion Criteria:

• Failure to obtain the participant's written informed consent
• Participation in any interventional study of products for hemophilia or other hemostasis disturbances treatment during 12 months prior to the study enrollment for participants who has retrospective data collection period and during 12 months after the study enrollment for all participants.

Male participants of all ages being treated with octocog alfa (Advate) for severe hemophilia A in 2021 will be enrolled in this study.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/. For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.