(1) Purpose: This study aimed to develop
a physiologically
based pharmacokinetic (PBPK) model to predict the trough concentration
(C
trough) of imatinib (IMA) at steady
state in patients and to explore the role of free concentration (f
up), α1-acid glycoprotein (AGP) level,
and organic cation transporter 1 (OCT1) activity/expression in clinical
efficacy. (2) Methods: The population PBPK model
was built using physicochemical and biochemical properties, metabolizing
and transporting kinetics, tissue distribution, and human physiological
parameters. (3) Results: The PBPK model successfully
predicted the C
trough of IMA administered
alone in chronic phase (CP) and accelerated phase (AP) patients, the C
trough of IMA co-administered with six modulators,
and C
trough in CP patients with hepatic
impairment. Most of the ratios between predicted and observed data
are within 0.70–1.30. Additionally, the recommendations for
dosing adjustments for IMA have been given under multiple clinical
uses. The sensitivity analysis showed that exploring the f
up and AGP level had a significant influence on the plasma C
trough of IMA. Meanwhile, the simulations also
revealed that OCT1 activity and expression had a significant impact
on the intracellular C
trough of IMA. (4) Conclusion: The current PBPK model can accurately predict
the IMA C
trough and provide appropriate
dosing adjustment recommendations in a variety of clinical situations.