Measurement of factor VIII activity of B-domain deleted recombinant factor VIII

Mikaelsson, Marianne; Oswaldsson, Ulla; Jankowski, Miłosz

doi:10.1016/s0037-1963(01)90104-0

Cited by 57 publications

(74 citation statements)

References 18 publications

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“…This may relate to the level of FVIII present in the test material but may also be partly a consequence of the pattern of reagents/kits used by the centres in our study since we noted one stage assay results were around 40% higher for users of Instrumentation laboratory reagents compared to results obtained by There are a number of studies reporting higher results for chromogenic assay compared to one stage assay in samples containing ReFacto ( 8,10,12,16) and ReFacto AF (14,15). This relationship is affected by the nature of the laboratory reagents used in one stage assays.…”

Section: Discussionmentioning

confidence: 71%

Factor VIII assay variability in postinfusion samples containing full length and B‐domain deleted FVIII

Kitchen¹,

Jennings²,

Makris

et al. 2016

Haemophilia

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Section: Discussionmentioning

confidence: 71%

Factor VIII assay variability in postinfusion samples containing full length and B‐domain deleted FVIII

Kitchen¹,

Jennings²,

Makris

et al. 2016

Haemophilia

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“…In these experiments, a dilution of FVIII-containing plasma samples is preincubated with thrombin for 30 seconds before the measurement of FVIII activity, using a clotting assay. 19 The data showed a rapid onset of activated FVIII-RH generation compared with FVIII-BDD ( Figure 1D); however, the increased activity of FVIII cannot be detected using the 1-stage aPTT assay.…”

Section: Biochemical Characterization Of Fviii R1645h (Fviii-rh) Variantmentioning

confidence: 93%

Minimal modification in the factor VIII B-domain sequence ameliorates the murine hemophilia A phenotype

Siner

Iacobelli

Sabatino

et al. 2013

Blood

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• The novel FVIII variant (FVIII-RH) has enhanced stability and procoagulant activity in both in vitro and in vivo models.• FVIII-RH is efficacious and safe; thus, it is an attractive molecule for protein replacement and as a transgene in gene-therapy strategies.Recombinant canine B-domain deleted (BDD) factor VIII (FVIII) is predominantly expressed as a single-chain protein and exhibits greater stability after activation compared with human FVIII-BDD. We generated a novel BDD-FVIII variant (FVIII-RH) with an amino acid change at the furin cleavage site within the B domain (position R1645H) that mimics the canine sequence (HHQR vs human RHQR). Compared with human FVIII-BDD, expression of FVIII-RH protein revealed a 2.5-fold increase in the single-chain form. Notably, FVIII-RH exhibited a twofold increase in biological activity compared with FVIII-BDD, likely due to its slower dissociation of the A2-domain upon thrombin activation. Injection of FVIII-RH protein in hemophilia A (HA) mice resulted in more efficacious hemostasis following vascular injury in both the macro-and microcirculation. These findings were successfully translated to adeno-associated viral (AAV)-based liver gene transfer in HA mice. Expression of circulating FVIII-RH was approximately twofold higher compared with AAV-FVIII-BDD-injected mice. Moreover, FVIII-RH exhibits superior procoagulant effects compared with FVIII-BDD following a series of hemostatic challenges. Notably, the immunogenicity of FVIII-RH did not differ from FVIII-BDD. Thus, FVIII-RH is an attractive bioengineered molecule for improving efficacy without increased immunogenicity and may be suitable for both protein-and genebased strategies for HA. (Blood. 2013;121(21):4396-4403)

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“…In contrast, the chromogenic substrate bioassay (CHS), recommended for the measurement of BDDr factor VIII:C [15] does not require the presence of all the other coagulation factors necessary for the OSC. The specific chromogenic substrate is hydrolysed by activated coagulation factor X (FXa), and its spectophotometric intensity is proportional to the factor VIII:C present in the sample.…”

Section: Introductionmentioning

confidence: 99%

Population pharmacokinetics of recombinant factor VIII:C (ReFacto®) in adult HIV-negative and HIV-positive haemophilia patients

Karafoulidou¹,

Súárez

Anastasopoulou³

et al. 2009

Eur J Clin Pharmacol

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Purpose The aim of this study was to explore possible differences in the pharmacokinetics (PK) of recombinant factor VIII:C (ReFacto® -ReFacto ) in HIV+ vs. HIVpatients and also differences in the chromogenic substrate bioassay (CHS) and one-stage clotting (OSC) methods. Methods Twenty-eight haemophilia A adults (20 HIV-and eight HIV+) were assayed with both the CHS and OSC methods. An average of two and six samples were collected per patient for HIV-/+, respectively, after one, and occasionally two more, prophylactic doses (mean 2,003 IU; range 1,000-4,300 IU). The observations were analysed with the mixed-effects (population) compartmental PK modelling package NONMEM (nonlinear mixed-effects modelling) and the FOCE (first-order conditional estimation) method. Base modelling was performed independently for the CHS and OSC bioassays for comparison, and covariate models and simulation tests were done only for the commonly used OSC bioassay. The final covariate model was validated using the bootstrap method. Monte Carlo simulations were used to estimate the expected probability of exceeding 20%, 40% or 60% of normal factor VIII:C in plasma after a single dose, corresponding to required levels for preventing mild, moderate and lifethreatening haemorrhages. Results One-compartment base-model population PK parameters were [mean parameter (interpatient variability %)] for CHS: clearance (CL)=2.56 dl h −1 (33.2%); volume of distribution (V)=34.8 dl (12.8%); and for OSC: CL= 3.83 dl h −1 (47.8%), V=53.7 dl (22.4%). The volumes differed significantly between the CHS and OSC methods (p<0.0001), and variabilities were higher for OSC. Nevertheless, the empirical half-lives (t 1/2 =l n (2) × V/CL) were similar for CHS and OSC, [(mean ± standard deviation (SD)], 9.5 ± 3 h and 10.2 ± 4 h, respectively. In covariate modelling with the OSC-derived model, HIV status (VIR) was a significant categorical predictor (p<0.005) for V.The final covariate models with OSC were for CL=3.93 + 0.09 × (WT-75) and for V=48.6 × (1 + 0.36 × VIR) + 0.55 × (WT-75); therefore, V for the typical HIV+ patient was 36% higher than for the HIV-patient. Conclusions Both HIV-and HIV+ patients showed 100% success with the 20% threshold at doses >20 IU/kg. HIVpatients receiving >50 IU/kg had a 100% expected chance of success for all thresholds. HIV+ patients for moderate or life-threatening haemorrhage treatment need 10 IU/kg more than the HIV-patient equivalent to have the same probability of success.

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Measurement of factor VIII activity of B-domain deleted recombinant factor VIII

Cited by 57 publications

References 18 publications

Factor VIII assay variability in postinfusion samples containing full length and B‐domain deleted FVIII

Factor VIII assay variability in postinfusion samples containing full length and B‐domain deleted FVIII

Minimal modification in the factor VIII B-domain sequence ameliorates the murine hemophilia A phenotype

Population pharmacokinetics of recombinant factor VIII:C (ReFacto®) in adult HIV-negative and HIV-positive haemophilia patients

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