bleeding disorder coagulation disorder
Conditions
Interventions
None listed
Sponsors
Universitair Medisch Centrum Utrecht
Eligibility
Age
2 Years to 99 Years
Inclusion criteria
Inclusion criteria: 1. Diagnosis of severe haemophilia A OR haemophilia B. ;AND 2A) Previously Untreated Patient (PUP,
Exclusion criteria
Exclusion criteria: - Documented auto-immune disease
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| The main study endpoint is the (absence or presence of an) antigen-specific immune response to FVIII or FIX, i.e. detectable anti-FVIII or anti-FIX antibodies (inhibitors) in respectively haemophilia A and B. This can be subdivided into the following: 1) The development of an antigen-specific immune response to FVIII or FIX (i.e. an inhibitor) during the first treatment episode in PUPs. * Defined as an inhibitor titer > 0.3 BU. 2) The eradication of an antigen-specific immune response / induction of tolerance to FVIII or FIX during ITI. * Defined as an inhibitor titer = 66% and T* FVIII >=6 hours / T* FIX >= 12 hours. In order to evaluate the mechanism of (primary and secondary) tolerance induction, the following parameters will be measured: 1. Using modified Bethesda assay: - FVIII/FIX inhibitor titer; read-out of the presence or absence of an anti-FVIII / anti-FIX immune response 2. Using flow cytometry: * Pro-inflammatory/immunogenic parametersdeterminants: - Number and percentage of FVIII/FIX-specific reactive B-cells - Number and percentage of FVIII/FIX reactive CD4+ T-cells (Teff) * Anti-inflammatory/regulatory parametersdeterminants: - Number and percentage of regulatory B cells (Bregs) - Number and percentage of regulatory T-cells (Treg) - Teff/Treg ratio - Number and percentage of myeloid derived suppressor cells (MDSCs) 3. Using Luminex: - Cytokine levels (concentration), differentiation between pro-inflammatory (TNF, IL-1, IL-2, IL-6) and anti-inflammatory cytokines (TGF-beta, IL-4, IL-10) Explanation: The endpoint, i.e. 1) inhibitor development yes/no and 2) inhibitor eradication yes/no during ITI, will be related to the (change in) immune profile and FVIII- or FIX reactivity in order to evaluate the mechanism of (primary and secondary) tolerance induction. Hereby the results will be analyzed both intra-individually as interindividually: I. Intra-individually; to detect changes in the antibody-specific immune response | — |
Secondary
| Measure | Time frame |
|---|---|
| The secondary study parameters are aimed at providing a detailed characterization of antigen-specific cells and their function related to FVIII or FIX. Specifically, we will measure: 1. Using cell culture-based functional assays: - T-cell activation assay: Activation/regulatory status of CD4+ T-cells after stimulation with FVIII or FIX (expressed as percentage of cells that are positive for the following markers: CD25, CD69, PD1, ICOS, CTLA4) - Treg suppressor assay: Suppressive function of regulatory T-cells, as measured with a Treg suppressor assay, expressed as percentage of inhibition 2. Using ELISA: - Amount and (iso)type of FVIII/FIX-specific antibody (In case of haemophilia A: reactivity to FVIII heavy chain vs. light chain) | — |
Countries
Netherlands
Outcome results
None listed