Better Methods for Novel Biomarkers Series: LC/MS Biomarker Assay Validation Strategies Using Surrogate Matrix and Surrogate Analyte Approaches

As interest increases in developing novel biomarker and biotherapeutic assays to support clinical development, so does the need to keep up with the pace of new discoveries and evolving fit-for-purpose methods.

One major challenge is that quantitation of biomarkers by LC–MS/MS is complicated by the presence of endogenous analytes. This challenge is most commonly overcome by calibration using an authentic standard spiked into a surrogate matrix devoid of the target analyte. A second approach involves use of a stable-isotope-labeled standard as a surrogate analyte to allow calibration in the actual biological matrix. For both methods, parallelism between calibration standards and the target analyte in biological matrix must be demonstrated in order to ensure accurate quantitation.

This presentation will discuss how the LCMS Biomarkers and Biologics Services business at Quintiles has partnered with a sponsor to develop methods that compare the surrogate matrix and surrogate analyte approaches for the analysis of five amino acids in human plasma: alanine, valine, methionine, leucine and isoleucine. In addition, methodology based on standard addition will be introduced, which enables a robust examination of parallelism in both surrogate analyte and surrogate matrix methods prior to formal validation. The speaker will present results from additional assays to introduce the standard-addition methodology and to highlight the strengths and weaknesses of each approach.

The manner in which Quintiles obtained comparable precision and accuracy by the surrogate matrix and surrogate analyte methods for the analysis of amino acids in human plasma will also be discussed. Both assays were well within tolerances prescribed by regulatory guidance for validation of xenobiotic assays.

See also: B.R. Jones, G.A. Schultz, J.A. Eckstein, B.L Ackermann, “Surrogate Matrix and Surrogate Analyte Approaches for Definitive Quantitation of Endogenous Biomolecules”, Bioanalysis 2012 Oct.; 4(19):2343-56.

Speaker

Barry R. Jones, Ph.D., Assistant Research Investigator, LCMS Biomarkers and Biologics, Quintiles Bioanalytical and ADME Labs

Dr. Barry R. Jones joined Quintiles in 2007 and the newly-formed LC/MS Biologics Group in 2008. His research is focused on the quantitative LC/MS/MS analysis of endogenous biomolecules on triple quadrupole instruments. Dr. Jones is particularly interested in the scientific challenges and regulatory strategies for validation of definitive LC/MS biomarker assays in a fit-for-purpose environment. He has presented work at several national and international meetings including podium presentations at the American Society of Mass Spectrometry (ASMS) and the European Bioanalytical Forum (EBF).

Prior to joining Quintiles, Dr. Jones led the Mass Spectrometry Facility at Binghamton University, N.Y. using Q-TOF and MALDI mass spectrometry and nanoESI techniques in support of proteomic research. He earned his Ph.D. in Physical Chemistry at Binghamton University in 2006.

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