Abstract
Clinical studies involving enzyme replacement therapies (ERTs) have increasingly utilized enzymatic activity assays to monitor efficacy and biofunction of the drug; as a result, these assays have become an important part of pharmacokinetic (PK) and pharmacodynamic assessments in ERT trials. This paper presents a two-step enzymatic activity assay for iduronate-2-sulfatase (I2S) (EC 3.1.6.13) which we have optimized to fit in 1 day and to complete in less than 6 h. The rapid assay presented here is a significant improvement over the original two-step method with run time of 24 h which spanned 2 days. The resulting 1 day assay is efficient, robust, reproducible, and better suited for use in pharmacokinetic studies. The method was fully validated in accordance with regulatory agency guidelines so that it could be implemented in PK studies. Validation of the method required additional modifications to circumvent limitations surrounding the calculation of accuracy. This challenge was overcome by developing strategies to determine both the expected and the measured values of validation samples in activity units. Subsequently, the method was validated in accordance with the FDA guidance for the validation of quantitative ligand binding assays (LBAs). Results of method development and optimization with focus on evaluations aimed at reducing the total assay run time as well as a summary of method validation performance are presented in this publication.
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References
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Acknowledgements
Mitra Azadeh, Luying Pan, and Yongchang Qiu are full time employees of Shire. Ruben Boado is a full time employee of ArmaGen. We thank Eurofins Pharma Bioanalytics Services, St Charles, MO, USA, contracted by Shire to perform valiation of the two-step activity method, for their services. We also thank the Shire Discovery Therapeutic Group for providing the IDUA.
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Communicated by: Francois Feillet, MD, PhD
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Synopsis
Effective optimization resulted in an I2S enzymatic activity assay which is rapid, more specific, more robust, highly reproducible, and hence better suited for application in clinical or nonclinical studies.
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Conflict of Interest
Mitra Azadeh, Luying Pan, Yongchang Qiu, and Ruben Boado declare that they have no conflict of interest.
Informed Consent/Animal Rights
This article does not contain any studies with human or animal subjects performed by any of the authors.
Funding
Funding for this work was provided by Shire.
Author Contributions
Mitra Azadeh was responsible for the design, planning, conduct, data analysis, and reporting of the work described in this publication; she also drafted this article. Luying Pan, Yongchang Qiu, Ruben Boado, and Mitra Azadeh equally contributed to the interpretation of the data and critical revisions of the article for important intellectual content.
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Azadeh, M., Pan, L., Qiu, Y., Boado, R. (2017). A Rapid Two-Step Iduronate-2-Sulfatatse Enzymatic Activity Assay for MPSII Pharmacokinetic Assessment. In: Morava, E., Baumgartner, M., Patterson, M., Rahman, S., Zschocke, J., Peters, V. (eds) JIMD Reports, Volume 38. JIMD Reports, vol 38. Springer, Berlin, Heidelberg. https://doi.org/10.1007/8904_2017_34
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DOI: https://doi.org/10.1007/8904_2017_34
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Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-662-56609-1
Online ISBN: 978-3-662-56610-7
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