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INTRODUCTION: Discrepancies in the measurement of modified factor VIII (FVIII) products have been recognized, highlighting the need for adjustments in clinical laboratory practices to ensure effective monitoring of patients treated with these products, particularly using the one-stage (activated partial thromboplastin time [aPTT]) assay. AIM: To assess the ability of clinical laboratories to measure the activity of BAY 94-9027, a PEGylated extended half-life FVIII product, using routine (predominantly one-stage) assays in clinical laboratories METHODS: Blinded samples of FVIII-deficient plasma spiked with defined levels of BAY 94-9027 and a recombinant FVIII product comparator were provided to 52 clinical laboratories that routinely conduct FVIII testing. Samples were provided at 3 concentrations (low, medium and high), and laboratories analysed the samples using routine in-house one-stage and, when available, chromogenic assays. Acceptable spiked recovery (accuracy) of the local laboratory methods to measure BAY 94-9027 was the primary endpoint of the study. RESULTS: Accurate FVIII measurements were obtained at all concentrations for both products using the chromogenic assay and most of the commonly used one-stage reagents, both ellagic acid and silica based. Two specific silica-based reagents, APTT-SP and PTT-A, underestimated BAY 94-9027 levels at all concentrations, consistent with previous findings. CONCLUSIONS: FVIII activity of BAY 94-9027 was accurately measured with most commonly used one-stage assays used in routine clinical practice. The chromogenic assay was also accurate. It is recommended that clinical laboratories identify and avoid specific inappropriate reagents, such as the APTT-SP and PTT-A, in their one-stage assays for FVIII monitoring.
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Pruebas de Coagulación Sanguínea/métodos , Factor VIII/uso terapéutico , Polietilenglicoles/uso terapéutico , Factor VIII/farmacología , Humanos , Laboratorios , Polietilenglicoles/farmacologíaRESUMEN
INTRODUCTION: BAY 81-8973 is a full-length, unmodified, recombinant human factor VIII (FVIII) with the same primary amino acid sequence as sucrose-formulated recombinant FVIII but produced with certain more advanced manufacturing technologies. AIM: This global laboratory study evaluated variability in measurement of BAY 81-8973 using one-stage and chromogenic assays compared with antihaemophilic factor (recombinant) plasma/albumin-free method (rAHF-PFM; Advate(®) ) under assay conditions routinely used in clinical laboratories. METHODS: BAY 81-8973 or rAHF-PFM was spiked into FVIII-deficient plasma at 0.043 (low), 0.375 (medium) and 0.865 (normal) IU mL(-1) . Participating laboratories analysed blinded samples and normal plasma in triplicate using their routine assay, reagents and standards. Results were analysed for intra- and interlaboratory variability. RESULTS: Forty-one laboratories in 11 countries participated in the study. One-stage assay and chromogenic assays were used by 40 and 10 laboratories, respectively; 9 laboratories used both assays. Intralaboratory variability was <11% for both assays and both products at all concentrations. Interlaboratory variability was highest at the low concentration in the chromogenic and one-stage assay for BAY 81-8973 (60.0% and 33.7%, respectively) and rAHF-PFM (51.0% and 30.8%) and was lowest at the normal concentration (BAY 81-8973, 5.4% and 14.0%; rAHF-PFM, 5.8% and 12.4%), which was similar to the plasma control (6.6% and 10.3%). The chromogenic:one-stage assay ratio ranged from 0.95 (low concentration) to 1.10 (normal concentration) for BAY 81-8973 and 0.96-1.18 for rAHF-PFM. CONCLUSIONS: BAY 81-8973 can be accurately measured in plasma using the one-stage and chromogenic assays routinely used in clinical laboratories without a product-specific standard.
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Factor VIII/análisis , Preparaciones Farmacéuticas/análisis , Plasma/química , Proteínas Recombinantes/análisis , Factor VIII/uso terapéutico , Hemofilia A/tratamiento farmacológico , Humanos , Cooperación Internacional , Laboratorios , Variaciones Dependientes del Observador , Proteínas Recombinantes/uso terapéuticoRESUMEN
UNLABELLED: Essentials Discrepancies can exist in factor VIII activity measured by the one-stage or chromogenic assays. LEOPOLD trial data were used to assess clinical impact of BAY 81-8973 potency assignment assay. Efficacy was not affected by the assay used for potency assignment and dosing of BAY 81-8973. Either assay may be used to measure factor VIII activity after BAY 81-8973 infusion. SUMMARY: Background Product-specific discrepancies have been reported for factor VIII (FVIII) activity determined with one-stage or chromogenic assays. Objective To assess the clinical impact of potency assignment of BAY 81-8973, a full-length, unmodified, recombinant human FVIII, by use of the chromogenic assay or chromogenic assay adjusted to mimic results obtained with the one-stage assay Patients/methods Patients aged 12-65 years with severe hemophilia A received BAY 81-8973 in LEOPOLD I (20-50 IU kg(-1) two or three times weekly [investigator decision]) and LEOPOLD II (randomized to 20-30 IU kg(-1) twice weekly, 30-40 IU kg(-1) three times weekly, or on-demand treatment). Both trials included two 6-month crossover periods in which potency labeling was determined with the chromogenic substrate assay as per the European Pharmacopoeia (CS/EP) or the chromogenic substrate assay adjusted to mimic results obtained with the one-stage assay (CS/ADJ). The annualized bleeding rate (ABR) and FVIII incremental recovery were assessed by the use of pooled data. Results The analysis was perfomed on 121 patients. Median (quartile [Q] 1; Q3) ABRs during the CS/EP and CS/ADJ periods were 1.98 (0; 5.92) and 1.98 (0; 7.34), respectively. The mean incremental recovery was > 2 IU dL(-1) per IU kg(-1) in both periods with the use of either assay for postinfusion FVIII measurements. The median (Q1; Q3) chromogenic/one-stage assay recovery ratio was 1.054 (0.892; 1.150) for the CS/EP period when a plasma standard was used for calibration. Conclusions No impact on the ABR was observed with chromogenic-based as compared with one-stage assay-based potency and dosing. Either assay may be used to determine FVIII plasma activity after infusion of BAY 81-8973 without the need for a product-specific standard.
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Factor VIII/uso terapéutico , Hemofilia A/tratamiento farmacológico , Adolescente , Adulto , Anciano , Pruebas de Coagulación Sanguínea , Niño , Compuestos Cromogénicos/química , Ensayos Clínicos como Asunto , Estudios Cruzados , Europa (Continente) , Hemorragia , Humanos , Persona de Mediana Edad , Plasma/química , Proteínas Recombinantes/uso terapéutico , Resultado del Tratamiento , Adulto JovenRESUMEN
Due to its pivotal role in the growth factor-mediated tumour cell migration, the adaptor protein phospholipase C-gamma1 (PLC-gamma1) is an appropriate target to block ultimately the spreading of EGFR/c-erbB-2-positive tumour cells, thereby minimising metastasis formation. Here, we present an approach to block PLC-gamma1 activity by using protein-based PLC-gamma1 inhibitors consisting of PLC-gamma1 SH2 domains, which were fused to the TAT-transduction domain to ensure a high protein transduction efficiency. Two proteins were generated containing one PLC-gamma1-SH2-domain (PS1-TAT) or two PLC-gamma1-SH2 domains (PS2-TAT). PS2-TAT treatment of the EGFR/c-erbB-2-positive cell line MDA-HER2 resulted in a reduction of the EGF-mediated PLC-gamma1 tyrosine phosphorylation of about 30%, concomitant with a complete abrogation of the EGF-driven calcium influx. In addition to this, long-term PS2-TAT treatment both reduces the EGF-mediated migration of about 75% combined with a markedly decreased time locomotion of single MDA-HER2 cells as well as decreases the proliferation of MDA-HER2 cells by about 50%. Due to its antitumoral capacity on EGFR/c-erbB-2-positive breast cancer cells, we conclude from our results that the protein-based PLC-gamma1 inhibitor PS2-TAT may be a means for novel adjuvant antitumour strategies to minimise metastasis formation because of the blockade of cell migration and proliferation.