Open AccessApplication of PBPK Modeling and Virtual Clinical Study Approaches to Predict the Outcomes of CYP2D6 Genotype‐Guided Dosing of Tamoxifen
Author(s) -
Nakamura Toshimichi,
Toshimoto Kota,
Lee Wooin,
Imamura Chiyo K.,
Tanigawara Yusuke,
Sugiyama Yuichi
Publication year - 2018
Publication title -
cpt: pharmacometrics and systems pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.53
H-Index - 37
ISSN - 2163-8306
DOI - 10.1002/psp4.12307
Subject(s) - tamoxifen , physiologically based pharmacokinetic modelling , cyp2d6 , dosing , medicine , pharmacology , pharmacokinetics , population , genotype , oncology , biology , cytochrome p450 , cancer , breast cancer , environmental health , metabolism , biochemistry , gene
The Tamoxifen Response by CYP2D6 Genotype‐based Treatment‐1 (TARGET‐1) study ( n = 180) was conducted from 2012–2017 in Japan to determine the efficacy of tamoxifen dosing guided by cytochrome P450 2D6 (CYP2D6) genotypes. To predict its outcomes prior to completion, we constructed the comprehensive physiologically based pharmacokinetic (PBPK) models of tamoxifen and its metabolites and performed virtual TARGET‐1 studies. Our analyses indicated that the expected probability to achieve the end point (demonstrating the superior efficacy of the escalated tamoxifen dose over the standard dose in patients carrying CYP2D6 variants) was 0.469 on average. As the population size of this virtual clinical study (VCS) increased, the expected probability was substantially increased (0.674 for n = 260). Our analyses also informed that the probability to achieve the end point in the TARGET‐1 study was negatively impacted by a large variability in endoxifen levels. Our current efforts demonstrate the promising utility of the PBPK modeling and VCS approaches in prospectively designing effective clinical trials.