A Collaborative Study to Establish the 2nd International Standard for Tissue Plasminogen Activator (t-PA)

Gaffney, Patrick J.; Curtis, A. D. M.

doi:10.1055/s-0038-1646067

Cited by 41 publications

(17 citation statements)

References 3 publications

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“…Stocks of the first IS were rapidly depleted, and a replacement was established by WHO in 1986. 29 The second IS, again sourced from a melanoma cell culture, was selected over a second (recombinant) candidate material produced in Chinese Hamster Ovary (CHO) cells for consistency with the first IS. In the years that followed, the recombinant tPA product (International Nonproprietary Name (INN) alteplase) emerged as the dominant product, and was therefore chosen as the source material for replacement of third IS for tPA (98/ 714).…”

Section: Second-generation Thrombolytic Agentsmentioning

confidence: 99%

Biological Standards for Potency Assignment to Fibrinolytic Agents Used in Thrombolytic Therapy

Thelwell

2014

Semin Thromb Hemost

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Thrombolytic drugs are used for the treatment of thrombotic disorders such as acute myocardial infarction, acute ischemic stroke, and pulmonary embolism. Biological standards are used for potency assignment to the range of fibrinolytic proteins used in thrombolytic therapy. The World Health Organization (WHO) International Standards are primary reference materials, calibrated in arbitrary units (international unit), assigned by collaborative study using the range of assay methods available at the time. Provided the standard and test material are equivalent, adhering to the principle of measuring like versus like, the exact nature of the assay method is unimportant. This approach has been applied successfully for several decades since the advent of fibrinolytic treatment, ensuring consistency for potency labeling and the correct dosing of patients. The emergence of generic biosimilar products and new recombinant variants poses a challenge to this system, where functional differences impact on the relative biological activity in different assay systems. A more demanding system of standardization may therefore be required on the basis of international reference materials with associated reference methods. WHO recognizes this, and where possible and practical is seeking to incorporate concepts of traceability, uncertainty, and commutability to International Standards. However, some caution is needed because limitations on the characterization of many complex biologicals remain real, and a flexible approach is required on the basis of real-world needs.

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Section: Second-generation Thrombolytic Agentsmentioning

confidence: 99%

Biological Standards for Potency Assignment to Fibrinolytic Agents Used in Thrombolytic Therapy

Thelwell

2014

Semin Thromb Hemost

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“…The cross-reactivities of these substrates to plasminogen activators and even to other blood serine proteases (e.g., proteases involved in the coagulation cascade) render it impossible to standardize SK, u-PA, and t-PA activities via the same measurement method. [Note: the international units (IU) of plasminogen activators are based on fibrin clot-lysis methods (6); however, given interlaboratory variation in estimating potency of a given preparation via clotlysis assays (7)(8)(9) and the presence of trace contaminants in fibrinogen preparations (which can prevent clot formation in the case of SK (10)), considerable confusion exists regarding the meaning of labeled "IU" values]. In addition, because the incubation times are very long (4.5 h) for conducting the typical chromogenic t-PA assay, results are not necessarily reliable (11) owing to the relatively short half-life of the PAs in plasma (12).…”

Section: Academic Pressmentioning

confidence: 99%

Electrochemical Assay of Plasminogen Activators in Plasma Using Polyion-Sensitive Membrane Electrode Detection

Chang

Meyerhoff

Yang

1999

Analytical Biochemistry

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“…Alternatively, t-PA protein concentration was determined with the Bradford assay (19), calibrated with t-PA. Specific fibrinolytic activities were determined on bovine fibrin plates (20) by comparison with the 2nd lnternational Reference Preparation for t-PA (code 861670) (21), obtained from the National Institute for Biological Standards and Control (London, U.K.). Alternatively, the activity of JMI-229 rt-PA was compared with that of Actilyse@ in a clot lysis assay.…”

Section: Assay Tbchniquesmentioning

confidence: 99%

Biochemical and Biological Properties of a Recombinant Tissue-Type Plasminogen Activator Derived from the Rat JMI-229 Cell Line

Lijnen

Webb²,

Hoef

et al. 1992

Thromb Haemost

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SummaryRecombinant tissue-type plasminogen activator (rt-PA), produced by expression of the genomic t-PA DNA from the JMI-229 cell line, which is of rat origin, in the host cell line, was purified to homogeneity. JMI-229 rt-PA was obtained essentially as a single chain molecule which was quantitatively converted to a two-chain moiety by treatment with plasmin. The plasminogen activating potential of single chain JMI-229 rt-PA was 5-fold lower than that of commercially available human rt-PA (Actilyse®) in the absence of fibrin, but comparable in the presence of fibrin; it showed a concentration-dependent binding to fibrin, with a significantly more pronounced binding than Actilyse® at low fibrin concentration (85 ± 8% versus 20 ± 7% at 0.025 mg/ml fibrin; p = 0.004). In human plasma in the absence of fibrin, the concentrations of both single chain and two-chain JMI-229 rt-PA required to induce 50% fibrinogen degradation in 2 h, were about 15-fold higher than those of Actilyse®. Both single chain and two-chain forms of JMI-229 rt-PA and of Actilyse® induced a similar time- and concentration-dependent lysis of a 125I-fibrin-labeled plasma clot immersed in human plasma, in the absence of significant systemic fibrinolytic activation. Equally effective concentrations (causing 50% clot lysis in 2 h) were 0.11 or 0.10 pg/ml for single chain or two-chain JMI-229 rt-PA, as compared to 0.11 or 0.15 pg/ml for single chain or two-chain Actilyse®. Continuous infusion over 60 min of single chain JMI-229 rt-PA or Actilyse® in hamsters with a 125I-fibrin-labeled pulmonary embolus, revealed a very similar thrombolytic potency (clot lysis versus dose) and specific thrombolytic activity (clot lysis versus steady state plasma antigen level of t-PA). The initial plasma half-life following intravenous bolus injection of 0.10 mg/kg in hamsters was equally short for JMI-229 rt-PA or Actilyse® (1.2 or 1.4 min respectively).It is concluded that JMI-229 rt-PA has a higher fibrin-affinity and a higher fibrin-specificity in human plasma in the absence of fibrin than Actilyse®, but a comparable thrombolytic potency in a hamster pulmonary embolism model.

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A Collaborative Study to Establish the 2nd International Standard for Tissue Plasminogen Activator (t-PA)

Cited by 41 publications

References 3 publications

Biological Standards for Potency Assignment to Fibrinolytic Agents Used in Thrombolytic Therapy

Biological Standards for Potency Assignment to Fibrinolytic Agents Used in Thrombolytic Therapy

Electrochemical Assay of Plasminogen Activators in Plasma Using Polyion-Sensitive Membrane Electrode Detection

Biochemical and Biological Properties of a Recombinant Tissue-Type Plasminogen Activator Derived from the Rat JMI-229 Cell Line

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