A survey of one‐stage and chromogenic potencies in therapeutic factor VIII concentrates

Hubbard, A. R.; Weller, Lynne J.; Bevan, Sally A.

doi:10.1046/j.1365-2141.2002.3406_1.x

Cited by 48 publications

(48 citation statements)

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“…Here a 24% higher potency was obtained for the one‐stage compared with the chromogenic method, and this is consistent with data shown by Hubbard et al . in previous studies [4,5]. These differences in potency between the one‐stage and chromogenic methods were found to be reduced for those labs that had followed the ISTH recommendation of using FVIII‐deficient plasma as a prediluent (Fig.…”

Section: Discussionmentioning

confidence: 78%

Variability in factor VIII concentrate measurement: results from SSC field collaborative studies

Raut¹,

Sands

Heath

et al. 2003

Journal of Thrombosis and Haemostasis

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Summary. Seven 'field' collaborative studies on factor (F)VIII concentrate potency measurements were carried out, using local routine methodology, standards and calculation of results. Data from five of the 12 different concentrates studied are described in detail. These studies revealed that, for the intermediate-purity and the recombinant FVIII concentrates, one-stage potencies were significantly lower than chromogenic potencies, whilst for the two high-purity FVIII concentrates one-stage potencies were significantly greater than chromogenic potencies. On comparing predilution methods for the intermediate-purity concentrate, equivalent potencies were obtained using either buffer or FVIII-deficient plasma as prediluent. For the two highpurity and the recombinant concentrates, potencies obtained using buffer as prediluent were significantly greater and lower, respectively, than potencies obtained using FVIII-deficient plasma as prediluent. Interlaboratory variabilities were compared over all 12 concentrates studied and coefficients of variation (CVs) for one-stage assays were found to be much greater than for chromogenic assays. This was true for all concentrates except for the intermediate-purity concentrate and samples A and B from the first study, where the reverse was true. Furthermore, much better CVs were obtained when using FVIII-deficient plasma than when using buffer as prediluent, for all FVIII concentrates except for the intermediatepurity concentrate where the reverse was true, and sample B where CVs were equivalent. Overall, CVs were far worse than those obtained in controlled collaborative studies. Generally, however, CVs were better with chromogenic assays and predilution in FVIII-deficient plasma, as is recommended by the International Society on Thrombosis and Haemostasis/Scientific and Standardization Committee, particularly for higher purity and recombinant concentrates.

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Section: Discussionmentioning

confidence: 78%

Variability in factor VIII concentrate measurement: results from SSC field collaborative studies

Raut¹,

Sands

Heath

et al. 2003

Journal of Thrombosis and Haemostasis

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“…There are many publications describing differences between one‐stage and chromogenic assays in post‐infusion samples. Differences can be observed of up to 40% for full‐length recombinant products . This can be abolished by use of a concentrate standard for assay calibration .…”

Section: Introductionmentioning

confidence: 99%

“…This can be abolished by use of a concentrate standard for assay calibration . In earlier studies, results of chromogenic assays have been up to 50% higher than those obtained by one‐stage assay for some B‐domain deleted (BDD) FVIII products with standard half‐lives . The laboratory reagents used in the assay have an impact on these differences, and use of the ReFacto AF laboratory standard (RLS) for one‐stage assay calibration has been shown to deliver agreement with chromogenic results .…”

Section: Introductionmentioning

confidence: 99%

Clotting and chromogenic factor VIII assay variability in post‐infusion and spiked samples containing full‐length recombinant FVIII or recombinant factor VIII Fc fusion protein (rFVIIIFc)

Kitchen¹,

Jennings²,

Makris

et al. 2018

Int J Lab Hematology

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Introduction Variability in FVIII measurement is a recognized problem. There are limited data for samples containing recombinant Factor VIII Fc fusion protein (rFVIIIFc). Many studies use samples for which factor concentrate has been spiked into FVIII deficient plasma in vitro. This approach requires validation. Aim/Methods Four samples were distributed in a UK National External Quality Assessment Scheme for Blood Coagulation (NEQAS BC) survey. One contained Advate (full‐length recombinant FVIII) (rFVIII) added to FVIII deficient plasma, one was from a severe haemophilia A patient after infusion of Advate, one was prepared by addition of rFVIIIFc (marketed as Elocta/Eloctate) to FVIII deficient plasma and the fourth was collected from a severe haemophilia A patient following rFVIIIFc (Eloctate) infusion. Fifty‐three haemophilia centres (UK and Scandinavia) performed one‐stage FVIII assays and 27 performed chromogenic FVIII assays. Results/Conclusions One‐stage assays gave significantly lower results than chromogenic assays by 7% (P < 0.01) and 13%(P < 0.001) for post‐Advate and Advate spiked samples, and by 22% (P < 0.001) and 23% (P < 0.001) for post‐rFVIIIFc and rFVIIIFc spiked samples. The interlaboratory variation was similar for all samples, with CVs of 12%‐16% (chromogenic) and 10%‐13% (one stage). The data indicate that either product can be safely monitored by one‐stage or chromogenic assay. Spiked samples behaved in a similar way to post‐infusion samples for both products and could be substituted for post‐infusion samples for use in proficiency testing exercises (ie, samples were commutable).

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“…Substantial variability has been observed with the assay of high-purity factor products 2. For full-length products, rFVIII activity has been reported to be 20% lower with the one-stage assay compared with the chromogenic substrate assay; however, this difference can increase to up to 50% for the BDD-rFVIII ReFacto® (Pfizer Inc, New York, NY, USA) 6,7. The increased discrepancy with ReFacto® may be related to the phospholipid composition of the reagents in the one-stage assay 7.…”

Section: Introductionmentioning

confidence: 99%

Comparative field study evaluating the activity of recombinant factor VIII Fc fusion protein in plasma samples at clinical haemostasis laboratories

et al. 2013

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Discrepancies exist for some of the modified coagulation factors when assayed with different one-stage clotting and chromogenic substrate assay reagents. The aim of this study was to evaluate the performance of a recombinant factor VIII Fc fusion protein (rFVIIIFc), currently in clinical development for the treatment of severe haemophilia A, in a variety of one-stage clotting and chromogenic substrate assays in clinical haemostasis laboratories. Haemophilic plasma samples spiked with rFVIIIFc or Advate® at 0.05, 0.20 or 0.80 IU mL−1 were tested by 30 laboratories using their routine procedures and plasma standards. Data were evaluated for intra- and inter-laboratory variation, accuracy and possible rFVIIIFc-specific assay discrepancies. For the one-stage assay, mean recovery was 95% to 100% of expected for both Advate® and rFVIIIFc at 0.8 IU mL−1. Intra-laboratory percent coefficient of variance (CV) ranged from 6.3% to 7.8% for Advate®, and 6.0% to 10.3% for rFVIIIFc. Inter-laboratory CV ranged from 10% for Advate® and 16% for rFVIIIFc at 0.8 IU mL−1, to over 30% at 0.05 IU mL−1 for both products. For the chromogenic substrate assay, the average FVIII recovery was 107% ± 5% and 124% ± 8% of label potency across the three concentrations of Advate® and rFVIIIFc, respectively. Plasma rFVIIIFc levels can be monitored by either the one-stage or the chromogenic substrate assay routinely performed in clinical laboratories without the need for a product-specific rFVIIIFc laboratory standard. Accuracy by the one-stage assay was comparable to that of Advate®, while marginally higher results may be observed for rFVIIIFc when using the chromogenic assay.

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A survey of one‐stage and chromogenic potencies in therapeutic factor VIII concentrates

Abstract: *Significant dierence between 1-stage and chromogenic potencies at 5% level or less. Mean potency ratios were calculated from the results of two independent assays on each batch of product. n, number of batches tested.

Cited by 48 publications

References 4 publications

Variability in factor VIII concentrate measurement: results from SSC field collaborative studies

Variability in factor VIII concentrate measurement: results from SSC field collaborative studies

Clotting and chromogenic factor VIII assay variability in post‐infusion and spiked samples containing full‐length recombinant FVIII or recombinant factor VIII Fc fusion protein (rFVIIIFc)

Comparative field study evaluating the activity of recombinant factor VIII Fc fusion protein in plasma samples at clinical haemostasis laboratories

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