The goal of this observational study is to learn about the changes of antibodies and inhibitors against the coagulation factor VIII in patients with severe hemophilia A receiving emicizumab therapy. No additional visits or procedures are planned. Patients in this study will continue to receive their routine care and analysis will be done from left over samples from routine visits.
Study Type
OBSERVATIONAL
Enrollment
100
no intervention, only 3 different patients groups
University Hospital Frankfurt, Goethe University
Frankfurt am Main, Hesse, Germany
RECRUITINGFVIII inhibitor development in inhibitor negative subjects
Rate of FVIII inhibitor development during three years of emicizumab prophylaxis in inhibitor negative subjects. Assessed with Bethesda Assay (BU/ml). Number of patients who develop an FVIII inhibitor within the study period, but were FVIII inhibitor negative at start of the study.
Time frame: 3 years
FVIII antibody development in inhibitor negative subjects
Rate of FVIII antibody development during three years of emicizumab prophylaxis in inhibitor negative subjects. FVIII anti drug antibody (ADA) is assessed by FVIII specific ELISA (OD=Optical Density). Number of patients who develop an FVIII antibody (ADA) within the study period, but were FVIII inhibitor negative at start of the study.
Time frame: 3 years
FVIII inhibitor disappearance in inhibitor positive subjects
Rate of FVIII inhibitor disappearance during three years of emicizumab prophylaxis in inhibitor positive subjects. Assessed with Bethesda Assay (BU/ml). Number of patients who loose an FVIII inhibitor within the study period, but were FVIII inhibitor positive at start of the study.
Time frame: 3 years
FVIII antibody disappearance in inhibitor positive subjects
Rate of FVIII antibody disappearance during three years of emicizumab prophylaxis in inhibitor positive subjects. FVIII anti drug antibody (ADA) is assessed by FVIII specific ELISA (OD=Optical Density). Number of patients who develop an FVIII antibody within the study period, but were FVIII inhibitor positive at start of the study.
Time frame: 3 years
Anti-FVIII inhibitor development
Anti-FVIII inhibitor development (median BU/ml) over time. Assessed with Bethesda Assay (BU/ml). Description of inhibitor development in the different patient groups within the study period. Cut off is 0,6 BU/ml.
Time frame: 3 years
Anti-FVIII antibody development
Anti-FVIII antibody development (median arbitrary units, OD) over time. Description of antibody development in the different patient groups within the study period.
Time frame: 3 years
Time to negative inhibitor titers
Time to negative inhibitor titers. Assessed with Bethesda Assay (BU/ml). Description of the Time (days) observed for FVIII inhibitor disappearance within the study period in the patient groups. Cut off for inhibitor titer is 0,6 BU/ml.
Time frame: 3 years
Treatment of bleeds
Description of the use of FVIII and/or Bypassing agents treatment in addition to Emicizumab treatment in case of bleeds.
Time frame: 3 years
Response to treatment
Classification of bleeds as Effective, Partially Effective, Ineffective. Defined as: Effective: Bleeding episode responded to the usual number of injections or dose of FVIII as expected by the treating physician; Partially Effective: The bleeding episode responded with a higher number of injections and/or dose as expected by the treating physician; Ineffective: Routine failure to control hemostasis or hemostatic control required additional agents
Time frame: 3 years
Quality of the antibody response (FVIII epitopes)
Description of the location of FVIII epitopes over time, assessed by epitope mapping technique (ELISA)
Time frame: 3 years
Quality of the antibody response (IgG subclasses)
Description of a potential immune response over time, assessed by IgG subclass determination (ELISA).
Time frame: 3 years
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