Cellular Uptake and Efflux of Palbociclib In Vitro in Single Cell and Spheroid Models

Area of Science:

• Pharmacology and Drug Development
• Cancer Biology
• Biomathematics

Background:

• Effective cancer treatment relies on adequate drug distribution within tumors.
• Palbociclib, a CDK4/6 inhibitor, is used for metastatic breast cancer but has unique properties affecting tumor penetration.
• Understanding palbociclib's intratumoral pharmacokinetics is crucial for optimizing treatment efficacy.

Purpose of the Study:

• To investigate the in vitro penetration and distribution of palbociclib in tumor models.
• To explore the uptake and efflux dynamics of palbociclib in different cancer cell models.
• To develop and validate a mathematical model for predicting palbociclib distribution in tumors.

Main Methods:

• Utilized MCF-7 and DLD-1 cell lines grown as single cell suspensions (SCS) and spheroids.
• Quantified palbociclib uptake and efflux using liquid chromatography-tandem mass spectrometry.
• Developed a biomathematical model to simulate palbociclib transport and distribution.

Main Results:

• Achieved significantly higher intracellular palbociclib concentrations compared to media levels in both SCS and spheroids.
• Observed lower overall uptake in DLD-1 cells versus MCF-7 cells.
• Demonstrated slower uptake and efflux of palbociclib in spheroids compared to SCS, with the mathematical model supporting experimental findings.

Conclusions:

• Palbociclib exhibits substantial intracellular accumulation in vitro tumor models.
• Differences in uptake and efflux kinetics were noted between cell suspension and spheroid models.
• Biomathematical modeling shows promise for predicting intratumoral drug concentrations from plasma pharmacokinetics, aiding clinical application.