The Promises of Quantitative Transporter Proteomics: IVIVE to Precision Medicine

Date: September 03 2015
Presenter(s): Dr. Bhagwat Prasad

Webinar was presented on September 3rd, 2015 by Dr. Bhagwat Prasad, Principal investigator in the Department of Pharmaceutics, University of Washington (UW), Seattle, WA, USA

Summary of the presentation

Transporters play critical roles in drug clearance and disposition. The in vitro approaches such as recombinant cell-lines/vesicles expressing transporters are crucial to identify individual transporters involved in cellular uptake/efflux clearance of drugs. However, since in vitro models do not represent physiological expression and inter-individual variability of transporters, it is important to normalize the in vitro data by the in vivo protein expression or activity. While the sandwich-cultured human hepatocyte data are currently used as representative of in vivo hepatic expression/activity, these data usually result inaccurate in vivo predictions. Moreover, the viable primary cell based transporter models are not available for tissues other than the liver.

Therefore, it is critical that alternate approaches are used to better translate in vitro data to in vivo disposition (IVIVE). One such approach is to use human tissue transporter expression as a surrogate to generate physiologically relevant scaling factors for IVIVE of transporter disposition. To quantify drug transporters, LC-MS/MS targeted proteomics has emerged as a novel and promising technique. The latter relies on the quantification of surrogate peptides generated from the non-membrane domain of transporters. The technique has unique advantages, like, i) ability to simultaneously quantify multiple proteins, ii) very high selectivity derived from MRM feature of LC-MS/MS, and iii) reproducibility and data quality derived from multiple endpoints (peptides/fragments).

The transporter expression based physiological modeling approach could also be used to predict tissue concentration, i.e., the site of efficacy or toxicity, which is otherwise not routinely determined. Similarly, transporter quantification in banked tissues from a diverse population could be utilized to predict effect of age/development (ontogeny), diseases, genetic and epigenetic factors on transporter mediated clearance. These data are critical toward precision medicine. In this webinar, the potential application of LC-MS/MS transporter expression data in the IVIVE and prediction of inter-individual variability will be discussed with some examples from our recent work at the University of Washington.

Dr. Bhagwat Prasad is a principal investigator in the Department of Pharmaceutics, University of Washington (UW), Seattle, WA. Dr. Prasad’s expertise and training are on liquid chromatography-mass spectrometry (LC-MS), quantitative proteomics and pharmacokinetics. The broad interests of his laboratory are: i) to use quantitative proteomics to characterize population variability in the expression of drug transporters, metabolizing enzymes and receptors in children, and ii) then to use these data to develop systems/physiologically based pharmacokinetic and pharmacodynamic (PBPK and PKPD) models to predict pediatric drug disposition and response. Dr. Prasad is a principal investigator or co-investigator in various NIH/pharmaceutical industry funded research projects on quantitative proteomics, IVIVE and precision medicine. Before joining as a faculty at UW, Dr. Prasad worked with Prof. Jash Unadkat as a postdoc and a lead scientist of UW Research Affiliate Program on Transporters (UWRAPT). Dr. Prasad obtained his MS in 2006 and Ph.D. in 2010 in Pharmaceutical Sciences from NIPER, Mohali, India.