Case-control Pilot Study of the Immune Modulating Effect of FEIBA on Patients With Haemophilia A and Inhibitors

Inclusion Criteria: 1. The subject has signed and dated the Informed Consent form for participation in this study. 2. Age ≥ 18 years old. 3. Patient with severe haemophilia A (FVIII \<1%) and high-responding inhibitor (titre \>5 UB) at some point in their life, currently on therapy with FEIBA® to control bleeding. 4. Group 1: Patients in prophylaxis with FEIBA®: The patient has been on prophylaxis regimen with FEIBA® for at least 6 months prior to the study visit. Group 2: Patients on-demand regimen with FEIBA®: The patient has been under on-demand treatment with FEIBA® for at 6 months prior to the study visit. Exclusion Criteria: 1. The presence of any inflammatory condition at the time of the study visit or the previous 30 days that, according to the medical criterion, would affect the study objectives. 2. The patient is under immune tolerance treatment or has been at any time during the 30 days prior to the study visit. 3. The administration of any anti-inflammatory or immunosuppressive drug 15 days before the study visit. 4. Levels of CD4 \<200/l regardless of the HIV status. 5. Altered hepatic or renal function defined by the presence of abnormal levels of alanine aminotransferase (ALAT) or serum creatinine, respectively. 6. Administration of any haemostatic treatment to control bleeding within the 5 days prior to the study visit.