It is a matter of trust! Performing cross-laboratory-cross-technique comparisons in quantitative ADME proteomics

Numerous laboratories utilising a diverse range of techniques are quantifying the absolute abundance of drug transporter proteins by proteomic strategies in mammalian tissues and in vitro cell systems. Up to ten-fold differences in absolute abundances have been observed for specific transporter isoforms in non-matched samples between laboratories, for example, hepatic OATP1B1 (Prasad et al., 2014, Vildhede et al., 2014). It is important to establish if the variability’s exhibited are genuine to the biology of these samples, or if there is a bias of the methodology used between laboratories leading to the observed differences. Disparities in the techniques applied to obtain endpoint absolute abundances include those required to; select and generate the peptide standard(s); generate an enriched membrane fraction; denaturation/digestion of the proteins, the separation of the peptides by chromatography and the mass analysis of the selected peptide fragments (LC-MS/MS). A host of studies have been performed to investigate the manipulation of various aspects of the quantitative targeted absolute proteomics (QTAP) workflow within a single laboratory within the ADME proteomics field, however there is little in the way of cross laboratory comparisons using the same samples. The proposers have been involved in one such study and are willing to share their knowledge on this area and a larger Pan-European collaboration is also underway to investigate this important subject and progress within this study is advocated for dissemination at this roundtable discussion. This is an ideal forum for a panel discussion to bring together scientists from various spheres of pharmaceutical sciences to discuss this important topic. This burgeoning field should appeal to scientists of all levels of experience who have a keen interest in bio-analytics, proteomics, pharmacokinetics, IVIVE-PBPK, systems and translational pharmacology.

Prasad B. et al., 2014, Drug Metab Dispos 42:78-88.
Vildhede A. et al., 2014, Drug Metab Dispos 42:1210-1218.