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Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Inhibitor development in patients receiving recombinant factor VIII (Recombinate rAHF/Bioclate): a prospective
B M Ewenstein1, E D Gomperts, S Pearson
1Baxter BioScience, Westlake Village, CA 91362, USA. bruce_ewenstein@baxter.com
Haemophilia : the Official Journal of the World Federation of Hemophilia
|September 11, 2004
Summary
Inhibitor development is rare in previously treated patients (PTPs) receiving Recombinate rAHF/Bioclate, with incidence rates significantly lower than in previously untreated patients (PUPs). This large-scale pharmacovigilance study confirms infrequent inhibitor events in PTPs.
Area of Science:
- Pharmacovigilance and Hemophilia A Treatment
- Immunogenicity of Recombinant Factor VIII
Background:
- Clinical trials often lack the statistical power to detect infrequent adverse events like inhibitor development in previously treated patients (PTPs).
- Large-scale pharmacovigilance studies are crucial for assessing rare events in hemophilia A treatment.
- Recombinant factor VIII (rFVIII), including Recombinate rAHF/Bioclate, is a key therapy for hemophilia A.
Purpose of the Study:
- To prospectively collect and analyze inhibitor development reports worldwide for Recombinate rAHF recombinant factor VIII (rFVIII) from 1993-2002.
- To estimate the incidence of inhibitor development in previously untreated patients (PUPs) and previously treated patients (PTPs) receiving rFVIII.
- To compare the inhibitor incidence rates between PUPs and PTPs.
Main Methods:
- Prospective collection of inhibitor development reports globally for Recombinate rAHF/Bioclate.
- Compilation of annual International Units (IU) of rFVIII distributed to assess exposure levels.
- Utilized hemophilia A incidence/prevalence data and pooled consumption data from clinical trials to estimate inhibitor incidence in PUPs (1-50 exposure days) and PTPs (>50 exposure days).
Main Results:
- A total of 89 inhibitor cases were documented among 6.48 x 10^9 IU of Recombinate rAHF/Bioclate distributed.
- The incidence of all inhibitors was 11.9% in PUPs versus 0.123% in PTPs; high-titre inhibitors (>5 BU) were 5.96% in PUPs versus 0.0554% in PTPs.
- Inhibitor incidence rates in PTPs were approximately 1% of the rates observed in PUPs, with no evidence of lot association.
Conclusions:
- Inhibitor development is infrequent in previously treated patients (PTPs) receiving Recombinate rAHF/Bioclate.
- The incidence of inhibitors in PTPs is substantially lower than in previously untreated patients (PUPs).
- Pharmacovigilance data suggest inhibitor incidence in PTPs is low, though active monitoring in PUP trials indicates potentially higher true incidence in that group.
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